Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
[linux-2.6.git] / fs / ext4 / inode.c
1 /*
2  *  linux/fs/ext4/inode.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card (card@masi.ibp.fr)
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  *  from
10  *
11  *  linux/fs/minix/inode.c
12  *
13  *  Copyright (C) 1991, 1992  Linus Torvalds
14  *
15  *  64-bit file support on 64-bit platforms by Jakub Jelinek
16  *      (jj@sunsite.ms.mff.cuni.cz)
17  *
18  *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
19  */
20
21 #include <linux/module.h>
22 #include <linux/fs.h>
23 #include <linux/time.h>
24 #include <linux/jbd2.h>
25 #include <linux/highuid.h>
26 #include <linux/pagemap.h>
27 #include <linux/quotaops.h>
28 #include <linux/string.h>
29 #include <linux/buffer_head.h>
30 #include <linux/writeback.h>
31 #include <linux/pagevec.h>
32 #include <linux/mpage.h>
33 #include <linux/namei.h>
34 #include <linux/uio.h>
35 #include <linux/bio.h>
36 #include <linux/workqueue.h>
37 #include <linux/kernel.h>
38 #include <linux/printk.h>
39 #include <linux/slab.h>
40 #include <linux/ratelimit.h>
41
42 #include "ext4_jbd2.h"
43 #include "xattr.h"
44 #include "acl.h"
45 #include "ext4_extents.h"
46 #include "truncate.h"
47
48 #include <trace/events/ext4.h>
49
50 #define MPAGE_DA_EXTENT_TAIL 0x01
51
52 static inline int ext4_begin_ordered_truncate(struct inode *inode,
53                                               loff_t new_size)
54 {
55         trace_ext4_begin_ordered_truncate(inode, new_size);
56         /*
57          * If jinode is zero, then we never opened the file for
58          * writing, so there's no need to call
59          * jbd2_journal_begin_ordered_truncate() since there's no
60          * outstanding writes we need to flush.
61          */
62         if (!EXT4_I(inode)->jinode)
63                 return 0;
64         return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
65                                                    EXT4_I(inode)->jinode,
66                                                    new_size);
67 }
68
69 static void ext4_invalidatepage(struct page *page, unsigned long offset);
70 static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
71                                    struct buffer_head *bh_result, int create);
72 static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode);
73 static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
74 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
75 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
76
77 /*
78  * Test whether an inode is a fast symlink.
79  */
80 static int ext4_inode_is_fast_symlink(struct inode *inode)
81 {
82         int ea_blocks = EXT4_I(inode)->i_file_acl ?
83                 (inode->i_sb->s_blocksize >> 9) : 0;
84
85         return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
86 }
87
88 /*
89  * Restart the transaction associated with *handle.  This does a commit,
90  * so before we call here everything must be consistently dirtied against
91  * this transaction.
92  */
93 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
94                                  int nblocks)
95 {
96         int ret;
97
98         /*
99          * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
100          * moment, get_block can be called only for blocks inside i_size since
101          * page cache has been already dropped and writes are blocked by
102          * i_mutex. So we can safely drop the i_data_sem here.
103          */
104         BUG_ON(EXT4_JOURNAL(inode) == NULL);
105         jbd_debug(2, "restarting handle %p\n", handle);
106         up_write(&EXT4_I(inode)->i_data_sem);
107         ret = ext4_journal_restart(handle, nblocks);
108         down_write(&EXT4_I(inode)->i_data_sem);
109         ext4_discard_preallocations(inode);
110
111         return ret;
112 }
113
114 /*
115  * Called at the last iput() if i_nlink is zero.
116  */
117 void ext4_evict_inode(struct inode *inode)
118 {
119         handle_t *handle;
120         int err;
121
122         trace_ext4_evict_inode(inode);
123         if (inode->i_nlink) {
124                 /*
125                  * When journalling data dirty buffers are tracked only in the
126                  * journal. So although mm thinks everything is clean and
127                  * ready for reaping the inode might still have some pages to
128                  * write in the running transaction or waiting to be
129                  * checkpointed. Thus calling jbd2_journal_invalidatepage()
130                  * (via truncate_inode_pages()) to discard these buffers can
131                  * cause data loss. Also even if we did not discard these
132                  * buffers, we would have no way to find them after the inode
133                  * is reaped and thus user could see stale data if he tries to
134                  * read them before the transaction is checkpointed. So be
135                  * careful and force everything to disk here... We use
136                  * ei->i_datasync_tid to store the newest transaction
137                  * containing inode's data.
138                  *
139                  * Note that directories do not have this problem because they
140                  * don't use page cache.
141                  */
142                 if (ext4_should_journal_data(inode) &&
143                     (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode))) {
144                         journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
145                         tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
146
147                         jbd2_log_start_commit(journal, commit_tid);
148                         jbd2_log_wait_commit(journal, commit_tid);
149                         filemap_write_and_wait(&inode->i_data);
150                 }
151                 truncate_inode_pages(&inode->i_data, 0);
152                 goto no_delete;
153         }
154
155         if (!is_bad_inode(inode))
156                 dquot_initialize(inode);
157
158         if (ext4_should_order_data(inode))
159                 ext4_begin_ordered_truncate(inode, 0);
160         truncate_inode_pages(&inode->i_data, 0);
161
162         if (is_bad_inode(inode))
163                 goto no_delete;
164
165         handle = ext4_journal_start(inode, ext4_blocks_for_truncate(inode)+3);
166         if (IS_ERR(handle)) {
167                 ext4_std_error(inode->i_sb, PTR_ERR(handle));
168                 /*
169                  * If we're going to skip the normal cleanup, we still need to
170                  * make sure that the in-core orphan linked list is properly
171                  * cleaned up.
172                  */
173                 ext4_orphan_del(NULL, inode);
174                 goto no_delete;
175         }
176
177         if (IS_SYNC(inode))
178                 ext4_handle_sync(handle);
179         inode->i_size = 0;
180         err = ext4_mark_inode_dirty(handle, inode);
181         if (err) {
182                 ext4_warning(inode->i_sb,
183                              "couldn't mark inode dirty (err %d)", err);
184                 goto stop_handle;
185         }
186         if (inode->i_blocks)
187                 ext4_truncate(inode);
188
189         /*
190          * ext4_ext_truncate() doesn't reserve any slop when it
191          * restarts journal transactions; therefore there may not be
192          * enough credits left in the handle to remove the inode from
193          * the orphan list and set the dtime field.
194          */
195         if (!ext4_handle_has_enough_credits(handle, 3)) {
196                 err = ext4_journal_extend(handle, 3);
197                 if (err > 0)
198                         err = ext4_journal_restart(handle, 3);
199                 if (err != 0) {
200                         ext4_warning(inode->i_sb,
201                                      "couldn't extend journal (err %d)", err);
202                 stop_handle:
203                         ext4_journal_stop(handle);
204                         ext4_orphan_del(NULL, inode);
205                         goto no_delete;
206                 }
207         }
208
209         /*
210          * Kill off the orphan record which ext4_truncate created.
211          * AKPM: I think this can be inside the above `if'.
212          * Note that ext4_orphan_del() has to be able to cope with the
213          * deletion of a non-existent orphan - this is because we don't
214          * know if ext4_truncate() actually created an orphan record.
215          * (Well, we could do this if we need to, but heck - it works)
216          */
217         ext4_orphan_del(handle, inode);
218         EXT4_I(inode)->i_dtime  = get_seconds();
219
220         /*
221          * One subtle ordering requirement: if anything has gone wrong
222          * (transaction abort, IO errors, whatever), then we can still
223          * do these next steps (the fs will already have been marked as
224          * having errors), but we can't free the inode if the mark_dirty
225          * fails.
226          */
227         if (ext4_mark_inode_dirty(handle, inode))
228                 /* If that failed, just do the required in-core inode clear. */
229                 ext4_clear_inode(inode);
230         else
231                 ext4_free_inode(handle, inode);
232         ext4_journal_stop(handle);
233         return;
234 no_delete:
235         ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
236 }
237
238 #ifdef CONFIG_QUOTA
239 qsize_t *ext4_get_reserved_space(struct inode *inode)
240 {
241         return &EXT4_I(inode)->i_reserved_quota;
242 }
243 #endif
244
245 /*
246  * Calculate the number of metadata blocks need to reserve
247  * to allocate a block located at @lblock
248  */
249 static int ext4_calc_metadata_amount(struct inode *inode, ext4_lblk_t lblock)
250 {
251         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
252                 return ext4_ext_calc_metadata_amount(inode, lblock);
253
254         return ext4_ind_calc_metadata_amount(inode, lblock);
255 }
256
257 /*
258  * Called with i_data_sem down, which is important since we can call
259  * ext4_discard_preallocations() from here.
260  */
261 void ext4_da_update_reserve_space(struct inode *inode,
262                                         int used, int quota_claim)
263 {
264         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
265         struct ext4_inode_info *ei = EXT4_I(inode);
266
267         spin_lock(&ei->i_block_reservation_lock);
268         trace_ext4_da_update_reserve_space(inode, used);
269         if (unlikely(used > ei->i_reserved_data_blocks)) {
270                 ext4_msg(inode->i_sb, KERN_NOTICE, "%s: ino %lu, used %d "
271                          "with only %d reserved data blocks\n",
272                          __func__, inode->i_ino, used,
273                          ei->i_reserved_data_blocks);
274                 WARN_ON(1);
275                 used = ei->i_reserved_data_blocks;
276         }
277
278         /* Update per-inode reservations */
279         ei->i_reserved_data_blocks -= used;
280         ei->i_reserved_meta_blocks -= ei->i_allocated_meta_blocks;
281         percpu_counter_sub(&sbi->s_dirtyblocks_counter,
282                            used + ei->i_allocated_meta_blocks);
283         ei->i_allocated_meta_blocks = 0;
284
285         if (ei->i_reserved_data_blocks == 0) {
286                 /*
287                  * We can release all of the reserved metadata blocks
288                  * only when we have written all of the delayed
289                  * allocation blocks.
290                  */
291                 percpu_counter_sub(&sbi->s_dirtyblocks_counter,
292                                    ei->i_reserved_meta_blocks);
293                 ei->i_reserved_meta_blocks = 0;
294                 ei->i_da_metadata_calc_len = 0;
295         }
296         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
297
298         /* Update quota subsystem for data blocks */
299         if (quota_claim)
300                 dquot_claim_block(inode, used);
301         else {
302                 /*
303                  * We did fallocate with an offset that is already delayed
304                  * allocated. So on delayed allocated writeback we should
305                  * not re-claim the quota for fallocated blocks.
306                  */
307                 dquot_release_reservation_block(inode, used);
308         }
309
310         /*
311          * If we have done all the pending block allocations and if
312          * there aren't any writers on the inode, we can discard the
313          * inode's preallocations.
314          */
315         if ((ei->i_reserved_data_blocks == 0) &&
316             (atomic_read(&inode->i_writecount) == 0))
317                 ext4_discard_preallocations(inode);
318 }
319
320 static int __check_block_validity(struct inode *inode, const char *func,
321                                 unsigned int line,
322                                 struct ext4_map_blocks *map)
323 {
324         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
325                                    map->m_len)) {
326                 ext4_error_inode(inode, func, line, map->m_pblk,
327                                  "lblock %lu mapped to illegal pblock "
328                                  "(length %d)", (unsigned long) map->m_lblk,
329                                  map->m_len);
330                 return -EIO;
331         }
332         return 0;
333 }
334
335 #define check_block_validity(inode, map)        \
336         __check_block_validity((inode), __func__, __LINE__, (map))
337
338 /*
339  * Return the number of contiguous dirty pages in a given inode
340  * starting at page frame idx.
341  */
342 static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
343                                     unsigned int max_pages)
344 {
345         struct address_space *mapping = inode->i_mapping;
346         pgoff_t index;
347         struct pagevec pvec;
348         pgoff_t num = 0;
349         int i, nr_pages, done = 0;
350
351         if (max_pages == 0)
352                 return 0;
353         pagevec_init(&pvec, 0);
354         while (!done) {
355                 index = idx;
356                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
357                                               PAGECACHE_TAG_DIRTY,
358                                               (pgoff_t)PAGEVEC_SIZE);
359                 if (nr_pages == 0)
360                         break;
361                 for (i = 0; i < nr_pages; i++) {
362                         struct page *page = pvec.pages[i];
363                         struct buffer_head *bh, *head;
364
365                         lock_page(page);
366                         if (unlikely(page->mapping != mapping) ||
367                             !PageDirty(page) ||
368                             PageWriteback(page) ||
369                             page->index != idx) {
370                                 done = 1;
371                                 unlock_page(page);
372                                 break;
373                         }
374                         if (page_has_buffers(page)) {
375                                 bh = head = page_buffers(page);
376                                 do {
377                                         if (!buffer_delay(bh) &&
378                                             !buffer_unwritten(bh))
379                                                 done = 1;
380                                         bh = bh->b_this_page;
381                                 } while (!done && (bh != head));
382                         }
383                         unlock_page(page);
384                         if (done)
385                                 break;
386                         idx++;
387                         num++;
388                         if (num >= max_pages) {
389                                 done = 1;
390                                 break;
391                         }
392                 }
393                 pagevec_release(&pvec);
394         }
395         return num;
396 }
397
398 /*
399  * The ext4_map_blocks() function tries to look up the requested blocks,
400  * and returns if the blocks are already mapped.
401  *
402  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
403  * and store the allocated blocks in the result buffer head and mark it
404  * mapped.
405  *
406  * If file type is extents based, it will call ext4_ext_map_blocks(),
407  * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
408  * based files
409  *
410  * On success, it returns the number of blocks being mapped or allocate.
411  * if create==0 and the blocks are pre-allocated and uninitialized block,
412  * the result buffer head is unmapped. If the create ==1, it will make sure
413  * the buffer head is mapped.
414  *
415  * It returns 0 if plain look up failed (blocks have not been allocated), in
416  * that casem, buffer head is unmapped
417  *
418  * It returns the error in case of allocation failure.
419  */
420 int ext4_map_blocks(handle_t *handle, struct inode *inode,
421                     struct ext4_map_blocks *map, int flags)
422 {
423         int retval;
424
425         map->m_flags = 0;
426         ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
427                   "logical block %lu\n", inode->i_ino, flags, map->m_len,
428                   (unsigned long) map->m_lblk);
429         /*
430          * Try to see if we can get the block without requesting a new
431          * file system block.
432          */
433         down_read((&EXT4_I(inode)->i_data_sem));
434         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
435                 retval = ext4_ext_map_blocks(handle, inode, map, 0);
436         } else {
437                 retval = ext4_ind_map_blocks(handle, inode, map, 0);
438         }
439         up_read((&EXT4_I(inode)->i_data_sem));
440
441         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
442                 int ret = check_block_validity(inode, map);
443                 if (ret != 0)
444                         return ret;
445         }
446
447         /* If it is only a block(s) look up */
448         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
449                 return retval;
450
451         /*
452          * Returns if the blocks have already allocated
453          *
454          * Note that if blocks have been preallocated
455          * ext4_ext_get_block() returns th create = 0
456          * with buffer head unmapped.
457          */
458         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
459                 return retval;
460
461         /*
462          * When we call get_blocks without the create flag, the
463          * BH_Unwritten flag could have gotten set if the blocks
464          * requested were part of a uninitialized extent.  We need to
465          * clear this flag now that we are committed to convert all or
466          * part of the uninitialized extent to be an initialized
467          * extent.  This is because we need to avoid the combination
468          * of BH_Unwritten and BH_Mapped flags being simultaneously
469          * set on the buffer_head.
470          */
471         map->m_flags &= ~EXT4_MAP_UNWRITTEN;
472
473         /*
474          * New blocks allocate and/or writing to uninitialized extent
475          * will possibly result in updating i_data, so we take
476          * the write lock of i_data_sem, and call get_blocks()
477          * with create == 1 flag.
478          */
479         down_write((&EXT4_I(inode)->i_data_sem));
480
481         /*
482          * if the caller is from delayed allocation writeout path
483          * we have already reserved fs blocks for allocation
484          * let the underlying get_block() function know to
485          * avoid double accounting
486          */
487         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
488                 ext4_set_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
489         /*
490          * We need to check for EXT4 here because migrate
491          * could have changed the inode type in between
492          */
493         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
494                 retval = ext4_ext_map_blocks(handle, inode, map, flags);
495         } else {
496                 retval = ext4_ind_map_blocks(handle, inode, map, flags);
497
498                 if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
499                         /*
500                          * We allocated new blocks which will result in
501                          * i_data's format changing.  Force the migrate
502                          * to fail by clearing migrate flags
503                          */
504                         ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
505                 }
506
507                 /*
508                  * Update reserved blocks/metadata blocks after successful
509                  * block allocation which had been deferred till now. We don't
510                  * support fallocate for non extent files. So we can update
511                  * reserve space here.
512                  */
513                 if ((retval > 0) &&
514                         (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
515                         ext4_da_update_reserve_space(inode, retval, 1);
516         }
517         if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
518                 ext4_clear_inode_state(inode, EXT4_STATE_DELALLOC_RESERVED);
519
520         up_write((&EXT4_I(inode)->i_data_sem));
521         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
522                 int ret = check_block_validity(inode, map);
523                 if (ret != 0)
524                         return ret;
525         }
526         return retval;
527 }
528
529 /* Maximum number of blocks we map for direct IO at once. */
530 #define DIO_MAX_BLOCKS 4096
531
532 static int _ext4_get_block(struct inode *inode, sector_t iblock,
533                            struct buffer_head *bh, int flags)
534 {
535         handle_t *handle = ext4_journal_current_handle();
536         struct ext4_map_blocks map;
537         int ret = 0, started = 0;
538         int dio_credits;
539
540         map.m_lblk = iblock;
541         map.m_len = bh->b_size >> inode->i_blkbits;
542
543         if (flags && !handle) {
544                 /* Direct IO write... */
545                 if (map.m_len > DIO_MAX_BLOCKS)
546                         map.m_len = DIO_MAX_BLOCKS;
547                 dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
548                 handle = ext4_journal_start(inode, dio_credits);
549                 if (IS_ERR(handle)) {
550                         ret = PTR_ERR(handle);
551                         return ret;
552                 }
553                 started = 1;
554         }
555
556         ret = ext4_map_blocks(handle, inode, &map, flags);
557         if (ret > 0) {
558                 map_bh(bh, inode->i_sb, map.m_pblk);
559                 bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
560                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
561                 ret = 0;
562         }
563         if (started)
564                 ext4_journal_stop(handle);
565         return ret;
566 }
567
568 int ext4_get_block(struct inode *inode, sector_t iblock,
569                    struct buffer_head *bh, int create)
570 {
571         return _ext4_get_block(inode, iblock, bh,
572                                create ? EXT4_GET_BLOCKS_CREATE : 0);
573 }
574
575 /*
576  * `handle' can be NULL if create is zero
577  */
578 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
579                                 ext4_lblk_t block, int create, int *errp)
580 {
581         struct ext4_map_blocks map;
582         struct buffer_head *bh;
583         int fatal = 0, err;
584
585         J_ASSERT(handle != NULL || create == 0);
586
587         map.m_lblk = block;
588         map.m_len = 1;
589         err = ext4_map_blocks(handle, inode, &map,
590                               create ? EXT4_GET_BLOCKS_CREATE : 0);
591
592         if (err < 0)
593                 *errp = err;
594         if (err <= 0)
595                 return NULL;
596         *errp = 0;
597
598         bh = sb_getblk(inode->i_sb, map.m_pblk);
599         if (!bh) {
600                 *errp = -EIO;
601                 return NULL;
602         }
603         if (map.m_flags & EXT4_MAP_NEW) {
604                 J_ASSERT(create != 0);
605                 J_ASSERT(handle != NULL);
606
607                 /*
608                  * Now that we do not always journal data, we should
609                  * keep in mind whether this should always journal the
610                  * new buffer as metadata.  For now, regular file
611                  * writes use ext4_get_block instead, so it's not a
612                  * problem.
613                  */
614                 lock_buffer(bh);
615                 BUFFER_TRACE(bh, "call get_create_access");
616                 fatal = ext4_journal_get_create_access(handle, bh);
617                 if (!fatal && !buffer_uptodate(bh)) {
618                         memset(bh->b_data, 0, inode->i_sb->s_blocksize);
619                         set_buffer_uptodate(bh);
620                 }
621                 unlock_buffer(bh);
622                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
623                 err = ext4_handle_dirty_metadata(handle, inode, bh);
624                 if (!fatal)
625                         fatal = err;
626         } else {
627                 BUFFER_TRACE(bh, "not a new buffer");
628         }
629         if (fatal) {
630                 *errp = fatal;
631                 brelse(bh);
632                 bh = NULL;
633         }
634         return bh;
635 }
636
637 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
638                                ext4_lblk_t block, int create, int *err)
639 {
640         struct buffer_head *bh;
641
642         bh = ext4_getblk(handle, inode, block, create, err);
643         if (!bh)
644                 return bh;
645         if (buffer_uptodate(bh))
646                 return bh;
647         ll_rw_block(READ_META, 1, &bh);
648         wait_on_buffer(bh);
649         if (buffer_uptodate(bh))
650                 return bh;
651         put_bh(bh);
652         *err = -EIO;
653         return NULL;
654 }
655
656 static int walk_page_buffers(handle_t *handle,
657                              struct buffer_head *head,
658                              unsigned from,
659                              unsigned to,
660                              int *partial,
661                              int (*fn)(handle_t *handle,
662                                        struct buffer_head *bh))
663 {
664         struct buffer_head *bh;
665         unsigned block_start, block_end;
666         unsigned blocksize = head->b_size;
667         int err, ret = 0;
668         struct buffer_head *next;
669
670         for (bh = head, block_start = 0;
671              ret == 0 && (bh != head || !block_start);
672              block_start = block_end, bh = next) {
673                 next = bh->b_this_page;
674                 block_end = block_start + blocksize;
675                 if (block_end <= from || block_start >= to) {
676                         if (partial && !buffer_uptodate(bh))
677                                 *partial = 1;
678                         continue;
679                 }
680                 err = (*fn)(handle, bh);
681                 if (!ret)
682                         ret = err;
683         }
684         return ret;
685 }
686
687 /*
688  * To preserve ordering, it is essential that the hole instantiation and
689  * the data write be encapsulated in a single transaction.  We cannot
690  * close off a transaction and start a new one between the ext4_get_block()
691  * and the commit_write().  So doing the jbd2_journal_start at the start of
692  * prepare_write() is the right place.
693  *
694  * Also, this function can nest inside ext4_writepage() ->
695  * block_write_full_page(). In that case, we *know* that ext4_writepage()
696  * has generated enough buffer credits to do the whole page.  So we won't
697  * block on the journal in that case, which is good, because the caller may
698  * be PF_MEMALLOC.
699  *
700  * By accident, ext4 can be reentered when a transaction is open via
701  * quota file writes.  If we were to commit the transaction while thus
702  * reentered, there can be a deadlock - we would be holding a quota
703  * lock, and the commit would never complete if another thread had a
704  * transaction open and was blocking on the quota lock - a ranking
705  * violation.
706  *
707  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
708  * will _not_ run commit under these circumstances because handle->h_ref
709  * is elevated.  We'll still have enough credits for the tiny quotafile
710  * write.
711  */
712 static int do_journal_get_write_access(handle_t *handle,
713                                        struct buffer_head *bh)
714 {
715         int dirty = buffer_dirty(bh);
716         int ret;
717
718         if (!buffer_mapped(bh) || buffer_freed(bh))
719                 return 0;
720         /*
721          * __block_write_begin() could have dirtied some buffers. Clean
722          * the dirty bit as jbd2_journal_get_write_access() could complain
723          * otherwise about fs integrity issues. Setting of the dirty bit
724          * by __block_write_begin() isn't a real problem here as we clear
725          * the bit before releasing a page lock and thus writeback cannot
726          * ever write the buffer.
727          */
728         if (dirty)
729                 clear_buffer_dirty(bh);
730         ret = ext4_journal_get_write_access(handle, bh);
731         if (!ret && dirty)
732                 ret = ext4_handle_dirty_metadata(handle, NULL, bh);
733         return ret;
734 }
735
736 static int ext4_get_block_write(struct inode *inode, sector_t iblock,
737                    struct buffer_head *bh_result, int create);
738 static int ext4_write_begin(struct file *file, struct address_space *mapping,
739                             loff_t pos, unsigned len, unsigned flags,
740                             struct page **pagep, void **fsdata)
741 {
742         struct inode *inode = mapping->host;
743         int ret, needed_blocks;
744         handle_t *handle;
745         int retries = 0;
746         struct page *page;
747         pgoff_t index;
748         unsigned from, to;
749
750         trace_ext4_write_begin(inode, pos, len, flags);
751         /*
752          * Reserve one block more for addition to orphan list in case
753          * we allocate blocks but write fails for some reason
754          */
755         needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
756         index = pos >> PAGE_CACHE_SHIFT;
757         from = pos & (PAGE_CACHE_SIZE - 1);
758         to = from + len;
759
760 retry:
761         handle = ext4_journal_start(inode, needed_blocks);
762         if (IS_ERR(handle)) {
763                 ret = PTR_ERR(handle);
764                 goto out;
765         }
766
767         /* We cannot recurse into the filesystem as the transaction is already
768          * started */
769         flags |= AOP_FLAG_NOFS;
770
771         page = grab_cache_page_write_begin(mapping, index, flags);
772         if (!page) {
773                 ext4_journal_stop(handle);
774                 ret = -ENOMEM;
775                 goto out;
776         }
777         *pagep = page;
778
779         if (ext4_should_dioread_nolock(inode))
780                 ret = __block_write_begin(page, pos, len, ext4_get_block_write);
781         else
782                 ret = __block_write_begin(page, pos, len, ext4_get_block);
783
784         if (!ret && ext4_should_journal_data(inode)) {
785                 ret = walk_page_buffers(handle, page_buffers(page),
786                                 from, to, NULL, do_journal_get_write_access);
787         }
788
789         if (ret) {
790                 unlock_page(page);
791                 page_cache_release(page);
792                 /*
793                  * __block_write_begin may have instantiated a few blocks
794                  * outside i_size.  Trim these off again. Don't need
795                  * i_size_read because we hold i_mutex.
796                  *
797                  * Add inode to orphan list in case we crash before
798                  * truncate finishes
799                  */
800                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
801                         ext4_orphan_add(handle, inode);
802
803                 ext4_journal_stop(handle);
804                 if (pos + len > inode->i_size) {
805                         ext4_truncate_failed_write(inode);
806                         /*
807                          * If truncate failed early the inode might
808                          * still be on the orphan list; we need to
809                          * make sure the inode is removed from the
810                          * orphan list in that case.
811                          */
812                         if (inode->i_nlink)
813                                 ext4_orphan_del(NULL, inode);
814                 }
815         }
816
817         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
818                 goto retry;
819 out:
820         return ret;
821 }
822
823 /* For write_end() in data=journal mode */
824 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
825 {
826         if (!buffer_mapped(bh) || buffer_freed(bh))
827                 return 0;
828         set_buffer_uptodate(bh);
829         return ext4_handle_dirty_metadata(handle, NULL, bh);
830 }
831
832 static int ext4_generic_write_end(struct file *file,
833                                   struct address_space *mapping,
834                                   loff_t pos, unsigned len, unsigned copied,
835                                   struct page *page, void *fsdata)
836 {
837         int i_size_changed = 0;
838         struct inode *inode = mapping->host;
839         handle_t *handle = ext4_journal_current_handle();
840
841         copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
842
843         /*
844          * No need to use i_size_read() here, the i_size
845          * cannot change under us because we hold i_mutex.
846          *
847          * But it's important to update i_size while still holding page lock:
848          * page writeout could otherwise come in and zero beyond i_size.
849          */
850         if (pos + copied > inode->i_size) {
851                 i_size_write(inode, pos + copied);
852                 i_size_changed = 1;
853         }
854
855         if (pos + copied >  EXT4_I(inode)->i_disksize) {
856                 /* We need to mark inode dirty even if
857                  * new_i_size is less that inode->i_size
858                  * bu greater than i_disksize.(hint delalloc)
859                  */
860                 ext4_update_i_disksize(inode, (pos + copied));
861                 i_size_changed = 1;
862         }
863         unlock_page(page);
864         page_cache_release(page);
865
866         /*
867          * Don't mark the inode dirty under page lock. First, it unnecessarily
868          * makes the holding time of page lock longer. Second, it forces lock
869          * ordering of page lock and transaction start for journaling
870          * filesystems.
871          */
872         if (i_size_changed)
873                 ext4_mark_inode_dirty(handle, inode);
874
875         return copied;
876 }
877
878 /*
879  * We need to pick up the new inode size which generic_commit_write gave us
880  * `file' can be NULL - eg, when called from page_symlink().
881  *
882  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
883  * buffers are managed internally.
884  */
885 static int ext4_ordered_write_end(struct file *file,
886                                   struct address_space *mapping,
887                                   loff_t pos, unsigned len, unsigned copied,
888                                   struct page *page, void *fsdata)
889 {
890         handle_t *handle = ext4_journal_current_handle();
891         struct inode *inode = mapping->host;
892         int ret = 0, ret2;
893
894         trace_ext4_ordered_write_end(inode, pos, len, copied);
895         ret = ext4_jbd2_file_inode(handle, inode);
896
897         if (ret == 0) {
898                 ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
899                                                         page, fsdata);
900                 copied = ret2;
901                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
902                         /* if we have allocated more blocks and copied
903                          * less. We will have blocks allocated outside
904                          * inode->i_size. So truncate them
905                          */
906                         ext4_orphan_add(handle, inode);
907                 if (ret2 < 0)
908                         ret = ret2;
909         }
910         ret2 = ext4_journal_stop(handle);
911         if (!ret)
912                 ret = ret2;
913
914         if (pos + len > inode->i_size) {
915                 ext4_truncate_failed_write(inode);
916                 /*
917                  * If truncate failed early the inode might still be
918                  * on the orphan list; we need to make sure the inode
919                  * is removed from the orphan list in that case.
920                  */
921                 if (inode->i_nlink)
922                         ext4_orphan_del(NULL, inode);
923         }
924
925
926         return ret ? ret : copied;
927 }
928
929 static int ext4_writeback_write_end(struct file *file,
930                                     struct address_space *mapping,
931                                     loff_t pos, unsigned len, unsigned copied,
932                                     struct page *page, void *fsdata)
933 {
934         handle_t *handle = ext4_journal_current_handle();
935         struct inode *inode = mapping->host;
936         int ret = 0, ret2;
937
938         trace_ext4_writeback_write_end(inode, pos, len, copied);
939         ret2 = ext4_generic_write_end(file, mapping, pos, len, copied,
940                                                         page, fsdata);
941         copied = ret2;
942         if (pos + len > inode->i_size && ext4_can_truncate(inode))
943                 /* if we have allocated more blocks and copied
944                  * less. We will have blocks allocated outside
945                  * inode->i_size. So truncate them
946                  */
947                 ext4_orphan_add(handle, inode);
948
949         if (ret2 < 0)
950                 ret = ret2;
951
952         ret2 = ext4_journal_stop(handle);
953         if (!ret)
954                 ret = ret2;
955
956         if (pos + len > inode->i_size) {
957                 ext4_truncate_failed_write(inode);
958                 /*
959                  * If truncate failed early the inode might still be
960                  * on the orphan list; we need to make sure the inode
961                  * is removed from the orphan list in that case.
962                  */
963                 if (inode->i_nlink)
964                         ext4_orphan_del(NULL, inode);
965         }
966
967         return ret ? ret : copied;
968 }
969
970 static int ext4_journalled_write_end(struct file *file,
971                                      struct address_space *mapping,
972                                      loff_t pos, unsigned len, unsigned copied,
973                                      struct page *page, void *fsdata)
974 {
975         handle_t *handle = ext4_journal_current_handle();
976         struct inode *inode = mapping->host;
977         int ret = 0, ret2;
978         int partial = 0;
979         unsigned from, to;
980         loff_t new_i_size;
981
982         trace_ext4_journalled_write_end(inode, pos, len, copied);
983         from = pos & (PAGE_CACHE_SIZE - 1);
984         to = from + len;
985
986         if (copied < len) {
987                 if (!PageUptodate(page))
988                         copied = 0;
989                 page_zero_new_buffers(page, from+copied, to);
990         }
991
992         ret = walk_page_buffers(handle, page_buffers(page), from,
993                                 to, &partial, write_end_fn);
994         if (!partial)
995                 SetPageUptodate(page);
996         new_i_size = pos + copied;
997         if (new_i_size > inode->i_size)
998                 i_size_write(inode, pos+copied);
999         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1000         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1001         if (new_i_size > EXT4_I(inode)->i_disksize) {
1002                 ext4_update_i_disksize(inode, new_i_size);
1003                 ret2 = ext4_mark_inode_dirty(handle, inode);
1004                 if (!ret)
1005                         ret = ret2;
1006         }
1007
1008         unlock_page(page);
1009         page_cache_release(page);
1010         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1011                 /* if we have allocated more blocks and copied
1012                  * less. We will have blocks allocated outside
1013                  * inode->i_size. So truncate them
1014                  */
1015                 ext4_orphan_add(handle, inode);
1016
1017         ret2 = ext4_journal_stop(handle);
1018         if (!ret)
1019                 ret = ret2;
1020         if (pos + len > inode->i_size) {
1021                 ext4_truncate_failed_write(inode);
1022                 /*
1023                  * If truncate failed early the inode might still be
1024                  * on the orphan list; we need to make sure the inode
1025                  * is removed from the orphan list in that case.
1026                  */
1027                 if (inode->i_nlink)
1028                         ext4_orphan_del(NULL, inode);
1029         }
1030
1031         return ret ? ret : copied;
1032 }
1033
1034 /*
1035  * Reserve a single block located at lblock
1036  */
1037 static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
1038 {
1039         int retries = 0;
1040         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1041         struct ext4_inode_info *ei = EXT4_I(inode);
1042         unsigned long md_needed;
1043         int ret;
1044
1045         /*
1046          * recalculate the amount of metadata blocks to reserve
1047          * in order to allocate nrblocks
1048          * worse case is one extent per block
1049          */
1050 repeat:
1051         spin_lock(&ei->i_block_reservation_lock);
1052         md_needed = ext4_calc_metadata_amount(inode, lblock);
1053         trace_ext4_da_reserve_space(inode, md_needed);
1054         spin_unlock(&ei->i_block_reservation_lock);
1055
1056         /*
1057          * We will charge metadata quota at writeout time; this saves
1058          * us from metadata over-estimation, though we may go over by
1059          * a small amount in the end.  Here we just reserve for data.
1060          */
1061         ret = dquot_reserve_block(inode, 1);
1062         if (ret)
1063                 return ret;
1064         /*
1065          * We do still charge estimated metadata to the sb though;
1066          * we cannot afford to run out of free blocks.
1067          */
1068         if (ext4_claim_free_blocks(sbi, md_needed + 1, 0)) {
1069                 dquot_release_reservation_block(inode, 1);
1070                 if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
1071                         yield();
1072                         goto repeat;
1073                 }
1074                 return -ENOSPC;
1075         }
1076         spin_lock(&ei->i_block_reservation_lock);
1077         ei->i_reserved_data_blocks++;
1078         ei->i_reserved_meta_blocks += md_needed;
1079         spin_unlock(&ei->i_block_reservation_lock);
1080
1081         return 0;       /* success */
1082 }
1083
1084 static void ext4_da_release_space(struct inode *inode, int to_free)
1085 {
1086         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1087         struct ext4_inode_info *ei = EXT4_I(inode);
1088
1089         if (!to_free)
1090                 return;         /* Nothing to release, exit */
1091
1092         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1093
1094         trace_ext4_da_release_space(inode, to_free);
1095         if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1096                 /*
1097                  * if there aren't enough reserved blocks, then the
1098                  * counter is messed up somewhere.  Since this
1099                  * function is called from invalidate page, it's
1100                  * harmless to return without any action.
1101                  */
1102                 ext4_msg(inode->i_sb, KERN_NOTICE, "ext4_da_release_space: "
1103                          "ino %lu, to_free %d with only %d reserved "
1104                          "data blocks\n", inode->i_ino, to_free,
1105                          ei->i_reserved_data_blocks);
1106                 WARN_ON(1);
1107                 to_free = ei->i_reserved_data_blocks;
1108         }
1109         ei->i_reserved_data_blocks -= to_free;
1110
1111         if (ei->i_reserved_data_blocks == 0) {
1112                 /*
1113                  * We can release all of the reserved metadata blocks
1114                  * only when we have written all of the delayed
1115                  * allocation blocks.
1116                  */
1117                 percpu_counter_sub(&sbi->s_dirtyblocks_counter,
1118                                    ei->i_reserved_meta_blocks);
1119                 ei->i_reserved_meta_blocks = 0;
1120                 ei->i_da_metadata_calc_len = 0;
1121         }
1122
1123         /* update fs dirty data blocks counter */
1124         percpu_counter_sub(&sbi->s_dirtyblocks_counter, to_free);
1125
1126         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1127
1128         dquot_release_reservation_block(inode, to_free);
1129 }
1130
1131 static void ext4_da_page_release_reservation(struct page *page,
1132                                              unsigned long offset)
1133 {
1134         int to_release = 0;
1135         struct buffer_head *head, *bh;
1136         unsigned int curr_off = 0;
1137
1138         head = page_buffers(page);
1139         bh = head;
1140         do {
1141                 unsigned int next_off = curr_off + bh->b_size;
1142
1143                 if ((offset <= curr_off) && (buffer_delay(bh))) {
1144                         to_release++;
1145                         clear_buffer_delay(bh);
1146                 }
1147                 curr_off = next_off;
1148         } while ((bh = bh->b_this_page) != head);
1149         ext4_da_release_space(page->mapping->host, to_release);
1150 }
1151
1152 /*
1153  * Delayed allocation stuff
1154  */
1155
1156 /*
1157  * mpage_da_submit_io - walks through extent of pages and try to write
1158  * them with writepage() call back
1159  *
1160  * @mpd->inode: inode
1161  * @mpd->first_page: first page of the extent
1162  * @mpd->next_page: page after the last page of the extent
1163  *
1164  * By the time mpage_da_submit_io() is called we expect all blocks
1165  * to be allocated. this may be wrong if allocation failed.
1166  *
1167  * As pages are already locked by write_cache_pages(), we can't use it
1168  */
1169 static int mpage_da_submit_io(struct mpage_da_data *mpd,
1170                               struct ext4_map_blocks *map)
1171 {
1172         struct pagevec pvec;
1173         unsigned long index, end;
1174         int ret = 0, err, nr_pages, i;
1175         struct inode *inode = mpd->inode;
1176         struct address_space *mapping = inode->i_mapping;
1177         loff_t size = i_size_read(inode);
1178         unsigned int len, block_start;
1179         struct buffer_head *bh, *page_bufs = NULL;
1180         int journal_data = ext4_should_journal_data(inode);
1181         sector_t pblock = 0, cur_logical = 0;
1182         struct ext4_io_submit io_submit;
1183
1184         BUG_ON(mpd->next_page <= mpd->first_page);
1185         memset(&io_submit, 0, sizeof(io_submit));
1186         /*
1187          * We need to start from the first_page to the next_page - 1
1188          * to make sure we also write the mapped dirty buffer_heads.
1189          * If we look at mpd->b_blocknr we would only be looking
1190          * at the currently mapped buffer_heads.
1191          */
1192         index = mpd->first_page;
1193         end = mpd->next_page - 1;
1194
1195         pagevec_init(&pvec, 0);
1196         while (index <= end) {
1197                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1198                 if (nr_pages == 0)
1199                         break;
1200                 for (i = 0; i < nr_pages; i++) {
1201                         int commit_write = 0, skip_page = 0;
1202                         struct page *page = pvec.pages[i];
1203
1204                         index = page->index;
1205                         if (index > end)
1206                                 break;
1207
1208                         if (index == size >> PAGE_CACHE_SHIFT)
1209                                 len = size & ~PAGE_CACHE_MASK;
1210                         else
1211                                 len = PAGE_CACHE_SIZE;
1212                         if (map) {
1213                                 cur_logical = index << (PAGE_CACHE_SHIFT -
1214                                                         inode->i_blkbits);
1215                                 pblock = map->m_pblk + (cur_logical -
1216                                                         map->m_lblk);
1217                         }
1218                         index++;
1219
1220                         BUG_ON(!PageLocked(page));
1221                         BUG_ON(PageWriteback(page));
1222
1223                         /*
1224                          * If the page does not have buffers (for
1225                          * whatever reason), try to create them using
1226                          * __block_write_begin.  If this fails,
1227                          * skip the page and move on.
1228                          */
1229                         if (!page_has_buffers(page)) {
1230                                 if (__block_write_begin(page, 0, len,
1231                                                 noalloc_get_block_write)) {
1232                                 skip_page:
1233                                         unlock_page(page);
1234                                         continue;
1235                                 }
1236                                 commit_write = 1;
1237                         }
1238
1239                         bh = page_bufs = page_buffers(page);
1240                         block_start = 0;
1241                         do {
1242                                 if (!bh)
1243                                         goto skip_page;
1244                                 if (map && (cur_logical >= map->m_lblk) &&
1245                                     (cur_logical <= (map->m_lblk +
1246                                                      (map->m_len - 1)))) {
1247                                         if (buffer_delay(bh)) {
1248                                                 clear_buffer_delay(bh);
1249                                                 bh->b_blocknr = pblock;
1250                                         }
1251                                         if (buffer_unwritten(bh) ||
1252                                             buffer_mapped(bh))
1253                                                 BUG_ON(bh->b_blocknr != pblock);
1254                                         if (map->m_flags & EXT4_MAP_UNINIT)
1255                                                 set_buffer_uninit(bh);
1256                                         clear_buffer_unwritten(bh);
1257                                 }
1258
1259                                 /* skip page if block allocation undone */
1260                                 if (buffer_delay(bh) || buffer_unwritten(bh))
1261                                         skip_page = 1;
1262                                 bh = bh->b_this_page;
1263                                 block_start += bh->b_size;
1264                                 cur_logical++;
1265                                 pblock++;
1266                         } while (bh != page_bufs);
1267
1268                         if (skip_page)
1269                                 goto skip_page;
1270
1271                         if (commit_write)
1272                                 /* mark the buffer_heads as dirty & uptodate */
1273                                 block_commit_write(page, 0, len);
1274
1275                         clear_page_dirty_for_io(page);
1276                         /*
1277                          * Delalloc doesn't support data journalling,
1278                          * but eventually maybe we'll lift this
1279                          * restriction.
1280                          */
1281                         if (unlikely(journal_data && PageChecked(page)))
1282                                 err = __ext4_journalled_writepage(page, len);
1283                         else if (test_opt(inode->i_sb, MBLK_IO_SUBMIT))
1284                                 err = ext4_bio_write_page(&io_submit, page,
1285                                                           len, mpd->wbc);
1286                         else
1287                                 err = block_write_full_page(page,
1288                                         noalloc_get_block_write, mpd->wbc);
1289
1290                         if (!err)
1291                                 mpd->pages_written++;
1292                         /*
1293                          * In error case, we have to continue because
1294                          * remaining pages are still locked
1295                          */
1296                         if (ret == 0)
1297                                 ret = err;
1298                 }
1299                 pagevec_release(&pvec);
1300         }
1301         ext4_io_submit(&io_submit);
1302         return ret;
1303 }
1304
1305 static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd)
1306 {
1307         int nr_pages, i;
1308         pgoff_t index, end;
1309         struct pagevec pvec;
1310         struct inode *inode = mpd->inode;
1311         struct address_space *mapping = inode->i_mapping;
1312
1313         index = mpd->first_page;
1314         end   = mpd->next_page - 1;
1315         while (index <= end) {
1316                 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE);
1317                 if (nr_pages == 0)
1318                         break;
1319                 for (i = 0; i < nr_pages; i++) {
1320                         struct page *page = pvec.pages[i];
1321                         if (page->index > end)
1322                                 break;
1323                         BUG_ON(!PageLocked(page));
1324                         BUG_ON(PageWriteback(page));
1325                         block_invalidatepage(page, 0);
1326                         ClearPageUptodate(page);
1327                         unlock_page(page);
1328                 }
1329                 index = pvec.pages[nr_pages - 1]->index + 1;
1330                 pagevec_release(&pvec);
1331         }
1332         return;
1333 }
1334
1335 static void ext4_print_free_blocks(struct inode *inode)
1336 {
1337         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1338         printk(KERN_CRIT "Total free blocks count %lld\n",
1339                ext4_count_free_blocks(inode->i_sb));
1340         printk(KERN_CRIT "Free/Dirty block details\n");
1341         printk(KERN_CRIT "free_blocks=%lld\n",
1342                (long long) percpu_counter_sum(&sbi->s_freeblocks_counter));
1343         printk(KERN_CRIT "dirty_blocks=%lld\n",
1344                (long long) percpu_counter_sum(&sbi->s_dirtyblocks_counter));
1345         printk(KERN_CRIT "Block reservation details\n");
1346         printk(KERN_CRIT "i_reserved_data_blocks=%u\n",
1347                EXT4_I(inode)->i_reserved_data_blocks);
1348         printk(KERN_CRIT "i_reserved_meta_blocks=%u\n",
1349                EXT4_I(inode)->i_reserved_meta_blocks);
1350         return;
1351 }
1352
1353 /*
1354  * mpage_da_map_and_submit - go through given space, map them
1355  *       if necessary, and then submit them for I/O
1356  *
1357  * @mpd - bh describing space
1358  *
1359  * The function skips space we know is already mapped to disk blocks.
1360  *
1361  */
1362 static void mpage_da_map_and_submit(struct mpage_da_data *mpd)
1363 {
1364         int err, blks, get_blocks_flags;
1365         struct ext4_map_blocks map, *mapp = NULL;
1366         sector_t next = mpd->b_blocknr;
1367         unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits;
1368         loff_t disksize = EXT4_I(mpd->inode)->i_disksize;
1369         handle_t *handle = NULL;
1370
1371         /*
1372          * If the blocks are mapped already, or we couldn't accumulate
1373          * any blocks, then proceed immediately to the submission stage.
1374          */
1375         if ((mpd->b_size == 0) ||
1376             ((mpd->b_state  & (1 << BH_Mapped)) &&
1377              !(mpd->b_state & (1 << BH_Delay)) &&
1378              !(mpd->b_state & (1 << BH_Unwritten))))
1379                 goto submit_io;
1380
1381         handle = ext4_journal_current_handle();
1382         BUG_ON(!handle);
1383
1384         /*
1385          * Call ext4_map_blocks() to allocate any delayed allocation
1386          * blocks, or to convert an uninitialized extent to be
1387          * initialized (in the case where we have written into
1388          * one or more preallocated blocks).
1389          *
1390          * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE to
1391          * indicate that we are on the delayed allocation path.  This
1392          * affects functions in many different parts of the allocation
1393          * call path.  This flag exists primarily because we don't
1394          * want to change *many* call functions, so ext4_map_blocks()
1395          * will set the EXT4_STATE_DELALLOC_RESERVED flag once the
1396          * inode's allocation semaphore is taken.
1397          *
1398          * If the blocks in questions were delalloc blocks, set
1399          * EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting
1400          * variables are updated after the blocks have been allocated.
1401          */
1402         map.m_lblk = next;
1403         map.m_len = max_blocks;
1404         get_blocks_flags = EXT4_GET_BLOCKS_CREATE;
1405         if (ext4_should_dioread_nolock(mpd->inode))
1406                 get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
1407         if (mpd->b_state & (1 << BH_Delay))
1408                 get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
1409
1410         blks = ext4_map_blocks(handle, mpd->inode, &map, get_blocks_flags);
1411         if (blks < 0) {
1412                 struct super_block *sb = mpd->inode->i_sb;
1413
1414                 err = blks;
1415                 /*
1416                  * If get block returns EAGAIN or ENOSPC and there
1417                  * appears to be free blocks we will just let
1418                  * mpage_da_submit_io() unlock all of the pages.
1419                  */
1420                 if (err == -EAGAIN)
1421                         goto submit_io;
1422
1423                 if (err == -ENOSPC &&
1424                     ext4_count_free_blocks(sb)) {
1425                         mpd->retval = err;
1426                         goto submit_io;
1427                 }
1428
1429                 /*
1430                  * get block failure will cause us to loop in
1431                  * writepages, because a_ops->writepage won't be able
1432                  * to make progress. The page will be redirtied by
1433                  * writepage and writepages will again try to write
1434                  * the same.
1435                  */
1436                 if (!(EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)) {
1437                         ext4_msg(sb, KERN_CRIT,
1438                                  "delayed block allocation failed for inode %lu "
1439                                  "at logical offset %llu with max blocks %zd "
1440                                  "with error %d", mpd->inode->i_ino,
1441                                  (unsigned long long) next,
1442                                  mpd->b_size >> mpd->inode->i_blkbits, err);
1443                         ext4_msg(sb, KERN_CRIT,
1444                                 "This should not happen!! Data will be lost\n");
1445                         if (err == -ENOSPC)
1446                                 ext4_print_free_blocks(mpd->inode);
1447                 }
1448                 /* invalidate all the pages */
1449                 ext4_da_block_invalidatepages(mpd);
1450
1451                 /* Mark this page range as having been completed */
1452                 mpd->io_done = 1;
1453                 return;
1454         }
1455         BUG_ON(blks == 0);
1456
1457         mapp = &map;
1458         if (map.m_flags & EXT4_MAP_NEW) {
1459                 struct block_device *bdev = mpd->inode->i_sb->s_bdev;
1460                 int i;
1461
1462                 for (i = 0; i < map.m_len; i++)
1463                         unmap_underlying_metadata(bdev, map.m_pblk + i);
1464         }
1465
1466         if (ext4_should_order_data(mpd->inode)) {
1467                 err = ext4_jbd2_file_inode(handle, mpd->inode);
1468                 if (err)
1469                         /* This only happens if the journal is aborted */
1470                         return;
1471         }
1472
1473         /*
1474          * Update on-disk size along with block allocation.
1475          */
1476         disksize = ((loff_t) next + blks) << mpd->inode->i_blkbits;
1477         if (disksize > i_size_read(mpd->inode))
1478                 disksize = i_size_read(mpd->inode);
1479         if (disksize > EXT4_I(mpd->inode)->i_disksize) {
1480                 ext4_update_i_disksize(mpd->inode, disksize);
1481                 err = ext4_mark_inode_dirty(handle, mpd->inode);
1482                 if (err)
1483                         ext4_error(mpd->inode->i_sb,
1484                                    "Failed to mark inode %lu dirty",
1485                                    mpd->inode->i_ino);
1486         }
1487
1488 submit_io:
1489         mpage_da_submit_io(mpd, mapp);
1490         mpd->io_done = 1;
1491 }
1492
1493 #define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
1494                 (1 << BH_Delay) | (1 << BH_Unwritten))
1495
1496 /*
1497  * mpage_add_bh_to_extent - try to add one more block to extent of blocks
1498  *
1499  * @mpd->lbh - extent of blocks
1500  * @logical - logical number of the block in the file
1501  * @bh - bh of the block (used to access block's state)
1502  *
1503  * the function is used to collect contig. blocks in same state
1504  */
1505 static void mpage_add_bh_to_extent(struct mpage_da_data *mpd,
1506                                    sector_t logical, size_t b_size,
1507                                    unsigned long b_state)
1508 {
1509         sector_t next;
1510         int nrblocks = mpd->b_size >> mpd->inode->i_blkbits;
1511
1512         /*
1513          * XXX Don't go larger than mballoc is willing to allocate
1514          * This is a stopgap solution.  We eventually need to fold
1515          * mpage_da_submit_io() into this function and then call
1516          * ext4_map_blocks() multiple times in a loop
1517          */
1518         if (nrblocks >= 8*1024*1024/mpd->inode->i_sb->s_blocksize)
1519                 goto flush_it;
1520
1521         /* check if thereserved journal credits might overflow */
1522         if (!(ext4_test_inode_flag(mpd->inode, EXT4_INODE_EXTENTS))) {
1523                 if (nrblocks >= EXT4_MAX_TRANS_DATA) {
1524                         /*
1525                          * With non-extent format we are limited by the journal
1526                          * credit available.  Total credit needed to insert
1527                          * nrblocks contiguous blocks is dependent on the
1528                          * nrblocks.  So limit nrblocks.
1529                          */
1530                         goto flush_it;
1531                 } else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) >
1532                                 EXT4_MAX_TRANS_DATA) {
1533                         /*
1534                          * Adding the new buffer_head would make it cross the
1535                          * allowed limit for which we have journal credit
1536                          * reserved. So limit the new bh->b_size
1537                          */
1538                         b_size = (EXT4_MAX_TRANS_DATA - nrblocks) <<
1539                                                 mpd->inode->i_blkbits;
1540                         /* we will do mpage_da_submit_io in the next loop */
1541                 }
1542         }
1543         /*
1544          * First block in the extent
1545          */
1546         if (mpd->b_size == 0) {
1547                 mpd->b_blocknr = logical;
1548                 mpd->b_size = b_size;
1549                 mpd->b_state = b_state & BH_FLAGS;
1550                 return;
1551         }
1552
1553         next = mpd->b_blocknr + nrblocks;
1554         /*
1555          * Can we merge the block to our big extent?
1556          */
1557         if (logical == next && (b_state & BH_FLAGS) == mpd->b_state) {
1558                 mpd->b_size += b_size;
1559                 return;
1560         }
1561
1562 flush_it:
1563         /*
1564          * We couldn't merge the block to our extent, so we
1565          * need to flush current  extent and start new one
1566          */
1567         mpage_da_map_and_submit(mpd);
1568         return;
1569 }
1570
1571 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
1572 {
1573         return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
1574 }
1575
1576 /*
1577  * This is a special get_blocks_t callback which is used by
1578  * ext4_da_write_begin().  It will either return mapped block or
1579  * reserve space for a single block.
1580  *
1581  * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
1582  * We also have b_blocknr = -1 and b_bdev initialized properly
1583  *
1584  * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
1585  * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
1586  * initialized properly.
1587  */
1588 static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
1589                                   struct buffer_head *bh, int create)
1590 {
1591         struct ext4_map_blocks map;
1592         int ret = 0;
1593         sector_t invalid_block = ~((sector_t) 0xffff);
1594
1595         if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
1596                 invalid_block = ~0;
1597
1598         BUG_ON(create == 0);
1599         BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
1600
1601         map.m_lblk = iblock;
1602         map.m_len = 1;
1603
1604         /*
1605          * first, we need to know whether the block is allocated already
1606          * preallocated blocks are unmapped but should treated
1607          * the same as allocated blocks.
1608          */
1609         ret = ext4_map_blocks(NULL, inode, &map, 0);
1610         if (ret < 0)
1611                 return ret;
1612         if (ret == 0) {
1613                 if (buffer_delay(bh))
1614                         return 0; /* Not sure this could or should happen */
1615                 /*
1616                  * XXX: __block_write_begin() unmaps passed block, is it OK?
1617                  */
1618                 ret = ext4_da_reserve_space(inode, iblock);
1619                 if (ret)
1620                         /* not enough space to reserve */
1621                         return ret;
1622
1623                 map_bh(bh, inode->i_sb, invalid_block);
1624                 set_buffer_new(bh);
1625                 set_buffer_delay(bh);
1626                 return 0;
1627         }
1628
1629         map_bh(bh, inode->i_sb, map.m_pblk);
1630         bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | map.m_flags;
1631
1632         if (buffer_unwritten(bh)) {
1633                 /* A delayed write to unwritten bh should be marked
1634                  * new and mapped.  Mapped ensures that we don't do
1635                  * get_block multiple times when we write to the same
1636                  * offset and new ensures that we do proper zero out
1637                  * for partial write.
1638                  */
1639                 set_buffer_new(bh);
1640                 set_buffer_mapped(bh);
1641         }
1642         return 0;
1643 }
1644
1645 /*
1646  * This function is used as a standard get_block_t calback function
1647  * when there is no desire to allocate any blocks.  It is used as a
1648  * callback function for block_write_begin() and block_write_full_page().
1649  * These functions should only try to map a single block at a time.
1650  *
1651  * Since this function doesn't do block allocations even if the caller
1652  * requests it by passing in create=1, it is critically important that
1653  * any caller checks to make sure that any buffer heads are returned
1654  * by this function are either all already mapped or marked for
1655  * delayed allocation before calling  block_write_full_page().  Otherwise,
1656  * b_blocknr could be left unitialized, and the page write functions will
1657  * be taken by surprise.
1658  */
1659 static int noalloc_get_block_write(struct inode *inode, sector_t iblock,
1660                                    struct buffer_head *bh_result, int create)
1661 {
1662         BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
1663         return _ext4_get_block(inode, iblock, bh_result, 0);
1664 }
1665
1666 static int bget_one(handle_t *handle, struct buffer_head *bh)
1667 {
1668         get_bh(bh);
1669         return 0;
1670 }
1671
1672 static int bput_one(handle_t *handle, struct buffer_head *bh)
1673 {
1674         put_bh(bh);
1675         return 0;
1676 }
1677
1678 static int __ext4_journalled_writepage(struct page *page,
1679                                        unsigned int len)
1680 {
1681         struct address_space *mapping = page->mapping;
1682         struct inode *inode = mapping->host;
1683         struct buffer_head *page_bufs;
1684         handle_t *handle = NULL;
1685         int ret = 0;
1686         int err;
1687
1688         ClearPageChecked(page);
1689         page_bufs = page_buffers(page);
1690         BUG_ON(!page_bufs);
1691         walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one);
1692         /* As soon as we unlock the page, it can go away, but we have
1693          * references to buffers so we are safe */
1694         unlock_page(page);
1695
1696         handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1697         if (IS_ERR(handle)) {
1698                 ret = PTR_ERR(handle);
1699                 goto out;
1700         }
1701
1702         ret = walk_page_buffers(handle, page_bufs, 0, len, NULL,
1703                                 do_journal_get_write_access);
1704
1705         err = walk_page_buffers(handle, page_bufs, 0, len, NULL,
1706                                 write_end_fn);
1707         if (ret == 0)
1708                 ret = err;
1709         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1710         err = ext4_journal_stop(handle);
1711         if (!ret)
1712                 ret = err;
1713
1714         walk_page_buffers(handle, page_bufs, 0, len, NULL, bput_one);
1715         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1716 out:
1717         return ret;
1718 }
1719
1720 static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode);
1721 static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate);
1722
1723 /*
1724  * Note that we don't need to start a transaction unless we're journaling data
1725  * because we should have holes filled from ext4_page_mkwrite(). We even don't
1726  * need to file the inode to the transaction's list in ordered mode because if
1727  * we are writing back data added by write(), the inode is already there and if
1728  * we are writing back data modified via mmap(), no one guarantees in which
1729  * transaction the data will hit the disk. In case we are journaling data, we
1730  * cannot start transaction directly because transaction start ranks above page
1731  * lock so we have to do some magic.
1732  *
1733  * This function can get called via...
1734  *   - ext4_da_writepages after taking page lock (have journal handle)
1735  *   - journal_submit_inode_data_buffers (no journal handle)
1736  *   - shrink_page_list via pdflush (no journal handle)
1737  *   - grab_page_cache when doing write_begin (have journal handle)
1738  *
1739  * We don't do any block allocation in this function. If we have page with
1740  * multiple blocks we need to write those buffer_heads that are mapped. This
1741  * is important for mmaped based write. So if we do with blocksize 1K
1742  * truncate(f, 1024);
1743  * a = mmap(f, 0, 4096);
1744  * a[0] = 'a';
1745  * truncate(f, 4096);
1746  * we have in the page first buffer_head mapped via page_mkwrite call back
1747  * but other bufer_heads would be unmapped but dirty(dirty done via the
1748  * do_wp_page). So writepage should write the first block. If we modify
1749  * the mmap area beyond 1024 we will again get a page_fault and the
1750  * page_mkwrite callback will do the block allocation and mark the
1751  * buffer_heads mapped.
1752  *
1753  * We redirty the page if we have any buffer_heads that is either delay or
1754  * unwritten in the page.
1755  *
1756  * We can get recursively called as show below.
1757  *
1758  *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
1759  *              ext4_writepage()
1760  *
1761  * But since we don't do any block allocation we should not deadlock.
1762  * Page also have the dirty flag cleared so we don't get recurive page_lock.
1763  */
1764 static int ext4_writepage(struct page *page,
1765                           struct writeback_control *wbc)
1766 {
1767         int ret = 0, commit_write = 0;
1768         loff_t size;
1769         unsigned int len;
1770         struct buffer_head *page_bufs = NULL;
1771         struct inode *inode = page->mapping->host;
1772
1773         trace_ext4_writepage(page);
1774         size = i_size_read(inode);
1775         if (page->index == size >> PAGE_CACHE_SHIFT)
1776                 len = size & ~PAGE_CACHE_MASK;
1777         else
1778                 len = PAGE_CACHE_SIZE;
1779
1780         /*
1781          * If the page does not have buffers (for whatever reason),
1782          * try to create them using __block_write_begin.  If this
1783          * fails, redirty the page and move on.
1784          */
1785         if (!page_has_buffers(page)) {
1786                 if (__block_write_begin(page, 0, len,
1787                                         noalloc_get_block_write)) {
1788                 redirty_page:
1789                         redirty_page_for_writepage(wbc, page);
1790                         unlock_page(page);
1791                         return 0;
1792                 }
1793                 commit_write = 1;
1794         }
1795         page_bufs = page_buffers(page);
1796         if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
1797                               ext4_bh_delay_or_unwritten)) {
1798                 /*
1799                  * We don't want to do block allocation, so redirty
1800                  * the page and return.  We may reach here when we do
1801                  * a journal commit via journal_submit_inode_data_buffers.
1802                  * We can also reach here via shrink_page_list
1803                  */
1804                 goto redirty_page;
1805         }
1806         if (commit_write)
1807                 /* now mark the buffer_heads as dirty and uptodate */
1808                 block_commit_write(page, 0, len);
1809
1810         if (PageChecked(page) && ext4_should_journal_data(inode))
1811                 /*
1812                  * It's mmapped pagecache.  Add buffers and journal it.  There
1813                  * doesn't seem much point in redirtying the page here.
1814                  */
1815                 return __ext4_journalled_writepage(page, len);
1816
1817         if (buffer_uninit(page_bufs)) {
1818                 ext4_set_bh_endio(page_bufs, inode);
1819                 ret = block_write_full_page_endio(page, noalloc_get_block_write,
1820                                             wbc, ext4_end_io_buffer_write);
1821         } else
1822                 ret = block_write_full_page(page, noalloc_get_block_write,
1823                                             wbc);
1824
1825         return ret;
1826 }
1827
1828 /*
1829  * This is called via ext4_da_writepages() to
1830  * calculate the total number of credits to reserve to fit
1831  * a single extent allocation into a single transaction,
1832  * ext4_da_writpeages() will loop calling this before
1833  * the block allocation.
1834  */
1835
1836 static int ext4_da_writepages_trans_blocks(struct inode *inode)
1837 {
1838         int max_blocks = EXT4_I(inode)->i_reserved_data_blocks;
1839
1840         /*
1841          * With non-extent format the journal credit needed to
1842          * insert nrblocks contiguous block is dependent on
1843          * number of contiguous block. So we will limit
1844          * number of contiguous block to a sane value
1845          */
1846         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) &&
1847             (max_blocks > EXT4_MAX_TRANS_DATA))
1848                 max_blocks = EXT4_MAX_TRANS_DATA;
1849
1850         return ext4_chunk_trans_blocks(inode, max_blocks);
1851 }
1852
1853 /*
1854  * write_cache_pages_da - walk the list of dirty pages of the given
1855  * address space and accumulate pages that need writing, and call
1856  * mpage_da_map_and_submit to map a single contiguous memory region
1857  * and then write them.
1858  */
1859 static int write_cache_pages_da(struct address_space *mapping,
1860                                 struct writeback_control *wbc,
1861                                 struct mpage_da_data *mpd,
1862                                 pgoff_t *done_index)
1863 {
1864         struct buffer_head      *bh, *head;
1865         struct inode            *inode = mapping->host;
1866         struct pagevec          pvec;
1867         unsigned int            nr_pages;
1868         sector_t                logical;
1869         pgoff_t                 index, end;
1870         long                    nr_to_write = wbc->nr_to_write;
1871         int                     i, tag, ret = 0;
1872
1873         memset(mpd, 0, sizeof(struct mpage_da_data));
1874         mpd->wbc = wbc;
1875         mpd->inode = inode;
1876         pagevec_init(&pvec, 0);
1877         index = wbc->range_start >> PAGE_CACHE_SHIFT;
1878         end = wbc->range_end >> PAGE_CACHE_SHIFT;
1879
1880         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
1881                 tag = PAGECACHE_TAG_TOWRITE;
1882         else
1883                 tag = PAGECACHE_TAG_DIRTY;
1884
1885         *done_index = index;
1886         while (index <= end) {
1887                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
1888                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
1889                 if (nr_pages == 0)
1890                         return 0;
1891
1892                 for (i = 0; i < nr_pages; i++) {
1893                         struct page *page = pvec.pages[i];
1894
1895                         /*
1896                          * At this point, the page may be truncated or
1897                          * invalidated (changing page->mapping to NULL), or
1898                          * even swizzled back from swapper_space to tmpfs file
1899                          * mapping. However, page->index will not change
1900                          * because we have a reference on the page.
1901                          */
1902                         if (page->index > end)
1903                                 goto out;
1904
1905                         *done_index = page->index + 1;
1906
1907                         /*
1908                          * If we can't merge this page, and we have
1909                          * accumulated an contiguous region, write it
1910                          */
1911                         if ((mpd->next_page != page->index) &&
1912                             (mpd->next_page != mpd->first_page)) {
1913                                 mpage_da_map_and_submit(mpd);
1914                                 goto ret_extent_tail;
1915                         }
1916
1917                         lock_page(page);
1918
1919                         /*
1920                          * If the page is no longer dirty, or its
1921                          * mapping no longer corresponds to inode we
1922                          * are writing (which means it has been
1923                          * truncated or invalidated), or the page is
1924                          * already under writeback and we are not
1925                          * doing a data integrity writeback, skip the page
1926                          */
1927                         if (!PageDirty(page) ||
1928                             (PageWriteback(page) &&
1929                              (wbc->sync_mode == WB_SYNC_NONE)) ||
1930                             unlikely(page->mapping != mapping)) {
1931                                 unlock_page(page);
1932                                 continue;
1933                         }
1934
1935                         wait_on_page_writeback(page);
1936                         BUG_ON(PageWriteback(page));
1937
1938                         if (mpd->next_page != page->index)
1939                                 mpd->first_page = page->index;
1940                         mpd->next_page = page->index + 1;
1941                         logical = (sector_t) page->index <<
1942                                 (PAGE_CACHE_SHIFT - inode->i_blkbits);
1943
1944                         if (!page_has_buffers(page)) {
1945                                 mpage_add_bh_to_extent(mpd, logical,
1946                                                        PAGE_CACHE_SIZE,
1947                                                        (1 << BH_Dirty) | (1 << BH_Uptodate));
1948                                 if (mpd->io_done)
1949                                         goto ret_extent_tail;
1950                         } else {
1951                                 /*
1952                                  * Page with regular buffer heads,
1953                                  * just add all dirty ones
1954                                  */
1955                                 head = page_buffers(page);
1956                                 bh = head;
1957                                 do {
1958                                         BUG_ON(buffer_locked(bh));
1959                                         /*
1960                                          * We need to try to allocate
1961                                          * unmapped blocks in the same page.
1962                                          * Otherwise we won't make progress
1963                                          * with the page in ext4_writepage
1964                                          */
1965                                         if (ext4_bh_delay_or_unwritten(NULL, bh)) {
1966                                                 mpage_add_bh_to_extent(mpd, logical,
1967                                                                        bh->b_size,
1968                                                                        bh->b_state);
1969                                                 if (mpd->io_done)
1970                                                         goto ret_extent_tail;
1971                                         } else if (buffer_dirty(bh) && (buffer_mapped(bh))) {
1972                                                 /*
1973                                                  * mapped dirty buffer. We need
1974                                                  * to update the b_state
1975                                                  * because we look at b_state
1976                                                  * in mpage_da_map_blocks.  We
1977                                                  * don't update b_size because
1978                                                  * if we find an unmapped
1979                                                  * buffer_head later we need to
1980                                                  * use the b_state flag of that
1981                                                  * buffer_head.
1982                                                  */
1983                                                 if (mpd->b_size == 0)
1984                                                         mpd->b_state = bh->b_state & BH_FLAGS;
1985                                         }
1986                                         logical++;
1987                                 } while ((bh = bh->b_this_page) != head);
1988                         }
1989
1990                         if (nr_to_write > 0) {
1991                                 nr_to_write--;
1992                                 if (nr_to_write == 0 &&
1993                                     wbc->sync_mode == WB_SYNC_NONE)
1994                                         /*
1995                                          * We stop writing back only if we are
1996                                          * not doing integrity sync. In case of
1997                                          * integrity sync we have to keep going
1998                                          * because someone may be concurrently
1999                                          * dirtying pages, and we might have
2000                                          * synced a lot of newly appeared dirty
2001                                          * pages, but have not synced all of the
2002                                          * old dirty pages.
2003                                          */
2004                                         goto out;
2005                         }
2006                 }
2007                 pagevec_release(&pvec);
2008                 cond_resched();
2009         }
2010         return 0;
2011 ret_extent_tail:
2012         ret = MPAGE_DA_EXTENT_TAIL;
2013 out:
2014         pagevec_release(&pvec);
2015         cond_resched();
2016         return ret;
2017 }
2018
2019
2020 static int ext4_da_writepages(struct address_space *mapping,
2021                               struct writeback_control *wbc)
2022 {
2023         pgoff_t index;
2024         int range_whole = 0;
2025         handle_t *handle = NULL;
2026         struct mpage_da_data mpd;
2027         struct inode *inode = mapping->host;
2028         int pages_written = 0;
2029         unsigned int max_pages;
2030         int range_cyclic, cycled = 1, io_done = 0;
2031         int needed_blocks, ret = 0;
2032         long desired_nr_to_write, nr_to_writebump = 0;
2033         loff_t range_start = wbc->range_start;
2034         struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2035         pgoff_t done_index = 0;
2036         pgoff_t end;
2037
2038         trace_ext4_da_writepages(inode, wbc);
2039
2040         /*
2041          * No pages to write? This is mainly a kludge to avoid starting
2042          * a transaction for special inodes like journal inode on last iput()
2043          * because that could violate lock ordering on umount
2044          */
2045         if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2046                 return 0;
2047
2048         /*
2049          * If the filesystem has aborted, it is read-only, so return
2050          * right away instead of dumping stack traces later on that
2051          * will obscure the real source of the problem.  We test
2052          * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2053          * the latter could be true if the filesystem is mounted
2054          * read-only, and in that case, ext4_da_writepages should
2055          * *never* be called, so if that ever happens, we would want
2056          * the stack trace.
2057          */
2058         if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))
2059                 return -EROFS;
2060
2061         if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2062                 range_whole = 1;
2063
2064         range_cyclic = wbc->range_cyclic;
2065         if (wbc->range_cyclic) {
2066                 index = mapping->writeback_index;
2067                 if (index)
2068                         cycled = 0;
2069                 wbc->range_start = index << PAGE_CACHE_SHIFT;
2070                 wbc->range_end  = LLONG_MAX;
2071                 wbc->range_cyclic = 0;
2072                 end = -1;
2073         } else {
2074                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
2075                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
2076         }
2077
2078         /*
2079          * This works around two forms of stupidity.  The first is in
2080          * the writeback code, which caps the maximum number of pages
2081          * written to be 1024 pages.  This is wrong on multiple
2082          * levels; different architectues have a different page size,
2083          * which changes the maximum amount of data which gets
2084          * written.  Secondly, 4 megabytes is way too small.  XFS
2085          * forces this value to be 16 megabytes by multiplying
2086          * nr_to_write parameter by four, and then relies on its
2087          * allocator to allocate larger extents to make them
2088          * contiguous.  Unfortunately this brings us to the second
2089          * stupidity, which is that ext4's mballoc code only allocates
2090          * at most 2048 blocks.  So we force contiguous writes up to
2091          * the number of dirty blocks in the inode, or
2092          * sbi->max_writeback_mb_bump whichever is smaller.
2093          */
2094         max_pages = sbi->s_max_writeback_mb_bump << (20 - PAGE_CACHE_SHIFT);
2095         if (!range_cyclic && range_whole) {
2096                 if (wbc->nr_to_write == LONG_MAX)
2097                         desired_nr_to_write = wbc->nr_to_write;
2098                 else
2099                         desired_nr_to_write = wbc->nr_to_write * 8;
2100         } else
2101                 desired_nr_to_write = ext4_num_dirty_pages(inode, index,
2102                                                            max_pages);
2103         if (desired_nr_to_write > max_pages)
2104                 desired_nr_to_write = max_pages;
2105
2106         if (wbc->nr_to_write < desired_nr_to_write) {
2107                 nr_to_writebump = desired_nr_to_write - wbc->nr_to_write;
2108                 wbc->nr_to_write = desired_nr_to_write;
2109         }
2110
2111 retry:
2112         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2113                 tag_pages_for_writeback(mapping, index, end);
2114
2115         while (!ret && wbc->nr_to_write > 0) {
2116
2117                 /*
2118                  * we  insert one extent at a time. So we need
2119                  * credit needed for single extent allocation.
2120                  * journalled mode is currently not supported
2121                  * by delalloc
2122                  */
2123                 BUG_ON(ext4_should_journal_data(inode));
2124                 needed_blocks = ext4_da_writepages_trans_blocks(inode);
2125
2126                 /* start a new transaction*/
2127                 handle = ext4_journal_start(inode, needed_blocks);
2128                 if (IS_ERR(handle)) {
2129                         ret = PTR_ERR(handle);
2130                         ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
2131                                "%ld pages, ino %lu; err %d", __func__,
2132                                 wbc->nr_to_write, inode->i_ino, ret);
2133                         goto out_writepages;
2134                 }
2135
2136                 /*
2137                  * Now call write_cache_pages_da() to find the next
2138                  * contiguous region of logical blocks that need
2139                  * blocks to be allocated by ext4 and submit them.
2140                  */
2141                 ret = write_cache_pages_da(mapping, wbc, &mpd, &done_index);
2142                 /*
2143                  * If we have a contiguous extent of pages and we
2144                  * haven't done the I/O yet, map the blocks and submit
2145                  * them for I/O.
2146                  */
2147                 if (!mpd.io_done && mpd.next_page != mpd.first_page) {
2148                         mpage_da_map_and_submit(&mpd);
2149                         ret = MPAGE_DA_EXTENT_TAIL;
2150                 }
2151                 trace_ext4_da_write_pages(inode, &mpd);
2152                 wbc->nr_to_write -= mpd.pages_written;
2153
2154                 ext4_journal_stop(handle);
2155
2156                 if ((mpd.retval == -ENOSPC) && sbi->s_journal) {
2157                         /* commit the transaction which would
2158                          * free blocks released in the transaction
2159                          * and try again
2160                          */
2161                         jbd2_journal_force_commit_nested(sbi->s_journal);
2162                         ret = 0;
2163                 } else if (ret == MPAGE_DA_EXTENT_TAIL) {
2164                         /*
2165                          * got one extent now try with
2166                          * rest of the pages
2167                          */
2168                         pages_written += mpd.pages_written;
2169                         ret = 0;
2170                         io_done = 1;
2171                 } else if (wbc->nr_to_write)
2172                         /*
2173                          * There is no more writeout needed
2174                          * or we requested for a noblocking writeout
2175                          * and we found the device congested
2176                          */
2177                         break;
2178         }
2179         if (!io_done && !cycled) {
2180                 cycled = 1;
2181                 index = 0;
2182                 wbc->range_start = index << PAGE_CACHE_SHIFT;
2183                 wbc->range_end  = mapping->writeback_index - 1;
2184                 goto retry;
2185         }
2186
2187         /* Update index */
2188         wbc->range_cyclic = range_cyclic;
2189         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2190                 /*
2191                  * set the writeback_index so that range_cyclic
2192                  * mode will write it back later
2193                  */
2194                 mapping->writeback_index = done_index;
2195
2196 out_writepages:
2197         wbc->nr_to_write -= nr_to_writebump;
2198         wbc->range_start = range_start;
2199         trace_ext4_da_writepages_result(inode, wbc, ret, pages_written);
2200         return ret;
2201 }
2202
2203 #define FALL_BACK_TO_NONDELALLOC 1
2204 static int ext4_nonda_switch(struct super_block *sb)
2205 {
2206         s64 free_blocks, dirty_blocks;
2207         struct ext4_sb_info *sbi = EXT4_SB(sb);
2208
2209         /*
2210          * switch to non delalloc mode if we are running low
2211          * on free block. The free block accounting via percpu
2212          * counters can get slightly wrong with percpu_counter_batch getting
2213          * accumulated on each CPU without updating global counters
2214          * Delalloc need an accurate free block accounting. So switch
2215          * to non delalloc when we are near to error range.
2216          */
2217         free_blocks  = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
2218         dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyblocks_counter);
2219         if (2 * free_blocks < 3 * dirty_blocks ||
2220                 free_blocks < (dirty_blocks + EXT4_FREEBLOCKS_WATERMARK)) {
2221                 /*
2222                  * free block count is less than 150% of dirty blocks
2223                  * or free blocks is less than watermark
2224                  */
2225                 return 1;
2226         }
2227         /*
2228          * Even if we don't switch but are nearing capacity,
2229          * start pushing delalloc when 1/2 of free blocks are dirty.
2230          */
2231         if (free_blocks < 2 * dirty_blocks)
2232                 writeback_inodes_sb_if_idle(sb);
2233
2234         return 0;
2235 }
2236
2237 static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
2238                                loff_t pos, unsigned len, unsigned flags,
2239                                struct page **pagep, void **fsdata)
2240 {
2241         int ret, retries = 0;
2242         struct page *page;
2243         pgoff_t index;
2244         struct inode *inode = mapping->host;
2245         handle_t *handle;
2246
2247         index = pos >> PAGE_CACHE_SHIFT;
2248
2249         if (ext4_nonda_switch(inode->i_sb)) {
2250                 *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
2251                 return ext4_write_begin(file, mapping, pos,
2252                                         len, flags, pagep, fsdata);
2253         }
2254         *fsdata = (void *)0;
2255         trace_ext4_da_write_begin(inode, pos, len, flags);
2256 retry:
2257         /*
2258          * With delayed allocation, we don't log the i_disksize update
2259          * if there is delayed block allocation. But we still need
2260          * to journalling the i_disksize update if writes to the end
2261          * of file which has an already mapped buffer.
2262          */
2263         handle = ext4_journal_start(inode, 1);
2264         if (IS_ERR(handle)) {
2265                 ret = PTR_ERR(handle);
2266                 goto out;
2267         }
2268         /* We cannot recurse into the filesystem as the transaction is already
2269          * started */
2270         flags |= AOP_FLAG_NOFS;
2271
2272         page = grab_cache_page_write_begin(mapping, index, flags);
2273         if (!page) {
2274                 ext4_journal_stop(handle);
2275                 ret = -ENOMEM;
2276                 goto out;
2277         }
2278         *pagep = page;
2279
2280         ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
2281         if (ret < 0) {
2282                 unlock_page(page);
2283                 ext4_journal_stop(handle);
2284                 page_cache_release(page);
2285                 /*
2286                  * block_write_begin may have instantiated a few blocks
2287                  * outside i_size.  Trim these off again. Don't need
2288                  * i_size_read because we hold i_mutex.
2289                  */
2290                 if (pos + len > inode->i_size)
2291                         ext4_truncate_failed_write(inode);
2292         }
2293
2294         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
2295                 goto retry;
2296 out:
2297         return ret;
2298 }
2299
2300 /*
2301  * Check if we should update i_disksize
2302  * when write to the end of file but not require block allocation
2303  */
2304 static int ext4_da_should_update_i_disksize(struct page *page,
2305                                             unsigned long offset)
2306 {
2307         struct buffer_head *bh;
2308         struct inode *inode = page->mapping->host;
2309         unsigned int idx;
2310         int i;
2311
2312         bh = page_buffers(page);
2313         idx = offset >> inode->i_blkbits;
2314
2315         for (i = 0; i < idx; i++)
2316                 bh = bh->b_this_page;
2317
2318         if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
2319                 return 0;
2320         return 1;
2321 }
2322
2323 static int ext4_da_write_end(struct file *file,
2324                              struct address_space *mapping,
2325                              loff_t pos, unsigned len, unsigned copied,
2326                              struct page *page, void *fsdata)
2327 {
2328         struct inode *inode = mapping->host;
2329         int ret = 0, ret2;
2330         handle_t *handle = ext4_journal_current_handle();
2331         loff_t new_i_size;
2332         unsigned long start, end;
2333         int write_mode = (int)(unsigned long)fsdata;
2334
2335         if (write_mode == FALL_BACK_TO_NONDELALLOC) {
2336                 if (ext4_should_order_data(inode)) {
2337                         return ext4_ordered_write_end(file, mapping, pos,
2338                                         len, copied, page, fsdata);
2339                 } else if (ext4_should_writeback_data(inode)) {
2340                         return ext4_writeback_write_end(file, mapping, pos,
2341                                         len, copied, page, fsdata);
2342                 } else {
2343                         BUG();
2344                 }
2345         }
2346
2347         trace_ext4_da_write_end(inode, pos, len, copied);
2348         start = pos & (PAGE_CACHE_SIZE - 1);
2349         end = start + copied - 1;
2350
2351         /*
2352          * generic_write_end() will run mark_inode_dirty() if i_size
2353          * changes.  So let's piggyback the i_disksize mark_inode_dirty
2354          * into that.
2355          */
2356
2357         new_i_size = pos + copied;
2358         if (new_i_size > EXT4_I(inode)->i_disksize) {
2359                 if (ext4_da_should_update_i_disksize(page, end)) {
2360                         down_write(&EXT4_I(inode)->i_data_sem);
2361                         if (new_i_size > EXT4_I(inode)->i_disksize) {
2362                                 /*
2363                                  * Updating i_disksize when extending file
2364                                  * without needing block allocation
2365                                  */
2366                                 if (ext4_should_order_data(inode))
2367                                         ret = ext4_jbd2_file_inode(handle,
2368                                                                    inode);
2369
2370                                 EXT4_I(inode)->i_disksize = new_i_size;
2371                         }
2372                         up_write(&EXT4_I(inode)->i_data_sem);
2373                         /* We need to mark inode dirty even if
2374                          * new_i_size is less that inode->i_size
2375                          * bu greater than i_disksize.(hint delalloc)
2376                          */
2377                         ext4_mark_inode_dirty(handle, inode);
2378                 }
2379         }
2380         ret2 = generic_write_end(file, mapping, pos, len, copied,
2381                                                         page, fsdata);
2382         copied = ret2;
2383         if (ret2 < 0)
2384                 ret = ret2;
2385         ret2 = ext4_journal_stop(handle);
2386         if (!ret)
2387                 ret = ret2;
2388
2389         return ret ? ret : copied;
2390 }
2391
2392 static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
2393 {
2394         /*
2395          * Drop reserved blocks
2396          */
2397         BUG_ON(!PageLocked(page));
2398         if (!page_has_buffers(page))
2399                 goto out;
2400
2401         ext4_da_page_release_reservation(page, offset);
2402
2403 out:
2404         ext4_invalidatepage(page, offset);
2405
2406         return;
2407 }
2408
2409 /*
2410  * Force all delayed allocation blocks to be allocated for a given inode.
2411  */
2412 int ext4_alloc_da_blocks(struct inode *inode)
2413 {
2414         trace_ext4_alloc_da_blocks(inode);
2415
2416         if (!EXT4_I(inode)->i_reserved_data_blocks &&
2417             !EXT4_I(inode)->i_reserved_meta_blocks)
2418                 return 0;
2419
2420         /*
2421          * We do something simple for now.  The filemap_flush() will
2422          * also start triggering a write of the data blocks, which is
2423          * not strictly speaking necessary (and for users of
2424          * laptop_mode, not even desirable).  However, to do otherwise
2425          * would require replicating code paths in:
2426          *
2427          * ext4_da_writepages() ->
2428          *    write_cache_pages() ---> (via passed in callback function)
2429          *        __mpage_da_writepage() -->
2430          *           mpage_add_bh_to_extent()
2431          *           mpage_da_map_blocks()
2432          *
2433          * The problem is that write_cache_pages(), located in
2434          * mm/page-writeback.c, marks pages clean in preparation for
2435          * doing I/O, which is not desirable if we're not planning on
2436          * doing I/O at all.
2437          *
2438          * We could call write_cache_pages(), and then redirty all of
2439          * the pages by calling redirty_page_for_writepage() but that
2440          * would be ugly in the extreme.  So instead we would need to
2441          * replicate parts of the code in the above functions,
2442          * simplifying them because we wouldn't actually intend to
2443          * write out the pages, but rather only collect contiguous
2444          * logical block extents, call the multi-block allocator, and
2445          * then update the buffer heads with the block allocations.
2446          *
2447          * For now, though, we'll cheat by calling filemap_flush(),
2448          * which will map the blocks, and start the I/O, but not
2449          * actually wait for the I/O to complete.
2450          */
2451         return filemap_flush(inode->i_mapping);
2452 }
2453
2454 /*
2455  * bmap() is special.  It gets used by applications such as lilo and by
2456  * the swapper to find the on-disk block of a specific piece of data.
2457  *
2458  * Naturally, this is dangerous if the block concerned is still in the
2459  * journal.  If somebody makes a swapfile on an ext4 data-journaling
2460  * filesystem and enables swap, then they may get a nasty shock when the
2461  * data getting swapped to that swapfile suddenly gets overwritten by
2462  * the original zero's written out previously to the journal and
2463  * awaiting writeback in the kernel's buffer cache.
2464  *
2465  * So, if we see any bmap calls here on a modified, data-journaled file,
2466  * take extra steps to flush any blocks which might be in the cache.
2467  */
2468 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
2469 {
2470         struct inode *inode = mapping->host;
2471         journal_t *journal;
2472         int err;
2473
2474         if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
2475                         test_opt(inode->i_sb, DELALLOC)) {
2476                 /*
2477                  * With delalloc we want to sync the file
2478                  * so that we can make sure we allocate
2479                  * blocks for file
2480                  */
2481                 filemap_write_and_wait(mapping);
2482         }
2483
2484         if (EXT4_JOURNAL(inode) &&
2485             ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
2486                 /*
2487                  * This is a REALLY heavyweight approach, but the use of
2488                  * bmap on dirty files is expected to be extremely rare:
2489                  * only if we run lilo or swapon on a freshly made file
2490                  * do we expect this to happen.
2491                  *
2492                  * (bmap requires CAP_SYS_RAWIO so this does not
2493                  * represent an unprivileged user DOS attack --- we'd be
2494                  * in trouble if mortal users could trigger this path at
2495                  * will.)
2496                  *
2497                  * NB. EXT4_STATE_JDATA is not set on files other than
2498                  * regular files.  If somebody wants to bmap a directory
2499                  * or symlink and gets confused because the buffer
2500                  * hasn't yet been flushed to disk, they deserve
2501                  * everything they get.
2502                  */
2503
2504                 ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
2505                 journal = EXT4_JOURNAL(inode);
2506                 jbd2_journal_lock_updates(journal);
2507                 err = jbd2_journal_flush(journal);
2508                 jbd2_journal_unlock_updates(journal);
2509
2510                 if (err)
2511                         return 0;
2512         }
2513
2514         return generic_block_bmap(mapping, block, ext4_get_block);
2515 }
2516
2517 static int ext4_readpage(struct file *file, struct page *page)
2518 {
2519         trace_ext4_readpage(page);
2520         return mpage_readpage(page, ext4_get_block);
2521 }
2522
2523 static int
2524 ext4_readpages(struct file *file, struct address_space *mapping,
2525                 struct list_head *pages, unsigned nr_pages)
2526 {
2527         return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
2528 }
2529
2530 static void ext4_invalidatepage_free_endio(struct page *page, unsigned long offset)
2531 {
2532         struct buffer_head *head, *bh;
2533         unsigned int curr_off = 0;
2534
2535         if (!page_has_buffers(page))
2536                 return;
2537         head = bh = page_buffers(page);
2538         do {
2539                 if (offset <= curr_off && test_clear_buffer_uninit(bh)
2540                                         && bh->b_private) {
2541                         ext4_free_io_end(bh->b_private);
2542                         bh->b_private = NULL;
2543                         bh->b_end_io = NULL;
2544                 }
2545                 curr_off = curr_off + bh->b_size;
2546                 bh = bh->b_this_page;
2547         } while (bh != head);
2548 }
2549
2550 static void ext4_invalidatepage(struct page *page, unsigned long offset)
2551 {
2552         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
2553
2554         trace_ext4_invalidatepage(page, offset);
2555
2556         /*
2557          * free any io_end structure allocated for buffers to be discarded
2558          */
2559         if (ext4_should_dioread_nolock(page->mapping->host))
2560                 ext4_invalidatepage_free_endio(page, offset);
2561         /*
2562          * If it's a full truncate we just forget about the pending dirtying
2563          */
2564         if (offset == 0)
2565                 ClearPageChecked(page);
2566
2567         if (journal)
2568                 jbd2_journal_invalidatepage(journal, page, offset);
2569         else
2570                 block_invalidatepage(page, offset);
2571 }
2572
2573 static int ext4_releasepage(struct page *page, gfp_t wait)
2574 {
2575         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
2576
2577         trace_ext4_releasepage(page);
2578
2579         WARN_ON(PageChecked(page));
2580         if (!page_has_buffers(page))
2581                 return 0;
2582         if (journal)
2583                 return jbd2_journal_try_to_free_buffers(journal, page, wait);
2584         else
2585                 return try_to_free_buffers(page);
2586 }
2587
2588 /*
2589  * ext4_get_block used when preparing for a DIO write or buffer write.
2590  * We allocate an uinitialized extent if blocks haven't been allocated.
2591  * The extent will be converted to initialized after the IO is complete.
2592  */
2593 static int ext4_get_block_write(struct inode *inode, sector_t iblock,
2594                    struct buffer_head *bh_result, int create)
2595 {
2596         ext4_debug("ext4_get_block_write: inode %lu, create flag %d\n",
2597                    inode->i_ino, create);
2598         return _ext4_get_block(inode, iblock, bh_result,
2599                                EXT4_GET_BLOCKS_IO_CREATE_EXT);
2600 }
2601
2602 static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
2603                             ssize_t size, void *private, int ret,
2604                             bool is_async)
2605 {
2606         struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
2607         ext4_io_end_t *io_end = iocb->private;
2608         struct workqueue_struct *wq;
2609         unsigned long flags;
2610         struct ext4_inode_info *ei;
2611
2612         /* if not async direct IO or dio with 0 bytes write, just return */
2613         if (!io_end || !size)
2614                 goto out;
2615
2616         ext_debug("ext4_end_io_dio(): io_end 0x%p"
2617                   "for inode %lu, iocb 0x%p, offset %llu, size %llu\n",
2618                   iocb->private, io_end->inode->i_ino, iocb, offset,
2619                   size);
2620
2621         /* if not aio dio with unwritten extents, just free io and return */
2622         if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
2623                 ext4_free_io_end(io_end);
2624                 iocb->private = NULL;
2625 out:
2626                 if (is_async)
2627                         aio_complete(iocb, ret, 0);
2628                 inode_dio_done(inode);
2629                 return;
2630         }
2631
2632         io_end->offset = offset;
2633         io_end->size = size;
2634         if (is_async) {
2635                 io_end->iocb = iocb;
2636                 io_end->result = ret;
2637         }
2638         wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
2639
2640         /* Add the io_end to per-inode completed aio dio list*/
2641         ei = EXT4_I(io_end->inode);
2642         spin_lock_irqsave(&ei->i_completed_io_lock, flags);
2643         list_add_tail(&io_end->list, &ei->i_completed_io_list);
2644         spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
2645
2646         /* queue the work to convert unwritten extents to written */
2647         queue_work(wq, &io_end->work);
2648         iocb->private = NULL;
2649
2650         /* XXX: probably should move into the real I/O completion handler */
2651         inode_dio_done(inode);
2652 }
2653
2654 static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate)
2655 {
2656         ext4_io_end_t *io_end = bh->b_private;
2657         struct workqueue_struct *wq;
2658         struct inode *inode;
2659         unsigned long flags;
2660
2661         if (!test_clear_buffer_uninit(bh) || !io_end)
2662                 goto out;
2663
2664         if (!(io_end->inode->i_sb->s_flags & MS_ACTIVE)) {
2665                 printk("sb umounted, discard end_io request for inode %lu\n",
2666                         io_end->inode->i_ino);
2667                 ext4_free_io_end(io_end);
2668                 goto out;
2669         }
2670
2671         io_end->flag = EXT4_IO_END_UNWRITTEN;
2672         inode = io_end->inode;
2673
2674         /* Add the io_end to per-inode completed io list*/
2675         spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
2676         list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
2677         spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
2678
2679         wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
2680         /* queue the work to convert unwritten extents to written */
2681         queue_work(wq, &io_end->work);
2682 out:
2683         bh->b_private = NULL;
2684         bh->b_end_io = NULL;
2685         clear_buffer_uninit(bh);
2686         end_buffer_async_write(bh, uptodate);
2687 }
2688
2689 static int ext4_set_bh_endio(struct buffer_head *bh, struct inode *inode)
2690 {
2691         ext4_io_end_t *io_end;
2692         struct page *page = bh->b_page;
2693         loff_t offset = (sector_t)page->index << PAGE_CACHE_SHIFT;
2694         size_t size = bh->b_size;
2695
2696 retry:
2697         io_end = ext4_init_io_end(inode, GFP_ATOMIC);
2698         if (!io_end) {
2699                 pr_warn_ratelimited("%s: allocation fail\n", __func__);
2700                 schedule();
2701                 goto retry;
2702         }
2703         io_end->offset = offset;
2704         io_end->size = size;
2705         /*
2706          * We need to hold a reference to the page to make sure it
2707          * doesn't get evicted before ext4_end_io_work() has a chance
2708          * to convert the extent from written to unwritten.
2709          */
2710         io_end->page = page;
2711         get_page(io_end->page);
2712
2713         bh->b_private = io_end;
2714         bh->b_end_io = ext4_end_io_buffer_write;
2715         return 0;
2716 }
2717
2718 /*
2719  * For ext4 extent files, ext4 will do direct-io write to holes,
2720  * preallocated extents, and those write extend the file, no need to
2721  * fall back to buffered IO.
2722  *
2723  * For holes, we fallocate those blocks, mark them as uninitialized
2724  * If those blocks were preallocated, we mark sure they are splited, but
2725  * still keep the range to write as uninitialized.
2726  *
2727  * The unwrritten extents will be converted to written when DIO is completed.
2728  * For async direct IO, since the IO may still pending when return, we
2729  * set up an end_io call back function, which will do the conversion
2730  * when async direct IO completed.
2731  *
2732  * If the O_DIRECT write will extend the file then add this inode to the
2733  * orphan list.  So recovery will truncate it back to the original size
2734  * if the machine crashes during the write.
2735  *
2736  */
2737 static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
2738                               const struct iovec *iov, loff_t offset,
2739                               unsigned long nr_segs)
2740 {
2741         struct file *file = iocb->ki_filp;
2742         struct inode *inode = file->f_mapping->host;
2743         ssize_t ret;
2744         size_t count = iov_length(iov, nr_segs);
2745
2746         loff_t final_size = offset + count;
2747         if (rw == WRITE && final_size <= inode->i_size) {
2748                 /*
2749                  * We could direct write to holes and fallocate.
2750                  *
2751                  * Allocated blocks to fill the hole are marked as uninitialized
2752                  * to prevent parallel buffered read to expose the stale data
2753                  * before DIO complete the data IO.
2754                  *
2755                  * As to previously fallocated extents, ext4 get_block
2756                  * will just simply mark the buffer mapped but still
2757                  * keep the extents uninitialized.
2758                  *
2759                  * for non AIO case, we will convert those unwritten extents
2760                  * to written after return back from blockdev_direct_IO.
2761                  *
2762                  * for async DIO, the conversion needs to be defered when
2763                  * the IO is completed. The ext4 end_io callback function
2764                  * will be called to take care of the conversion work.
2765                  * Here for async case, we allocate an io_end structure to
2766                  * hook to the iocb.
2767                  */
2768                 iocb->private = NULL;
2769                 EXT4_I(inode)->cur_aio_dio = NULL;
2770                 if (!is_sync_kiocb(iocb)) {
2771                         iocb->private = ext4_init_io_end(inode, GFP_NOFS);
2772                         if (!iocb->private)
2773                                 return -ENOMEM;
2774                         /*
2775                          * we save the io structure for current async
2776                          * direct IO, so that later ext4_map_blocks()
2777                          * could flag the io structure whether there
2778                          * is a unwritten extents needs to be converted
2779                          * when IO is completed.
2780                          */
2781                         EXT4_I(inode)->cur_aio_dio = iocb->private;
2782                 }
2783
2784                 ret = __blockdev_direct_IO(rw, iocb, inode,
2785                                          inode->i_sb->s_bdev, iov,
2786                                          offset, nr_segs,
2787                                          ext4_get_block_write,
2788                                          ext4_end_io_dio,
2789                                          NULL,
2790                                          DIO_LOCKING | DIO_SKIP_HOLES);
2791                 if (iocb->private)
2792                         EXT4_I(inode)->cur_aio_dio = NULL;
2793                 /*
2794                  * The io_end structure takes a reference to the inode,
2795                  * that structure needs to be destroyed and the
2796                  * reference to the inode need to be dropped, when IO is
2797                  * complete, even with 0 byte write, or failed.
2798                  *
2799                  * In the successful AIO DIO case, the io_end structure will be
2800                  * desctroyed and the reference to the inode will be dropped
2801                  * after the end_io call back function is called.
2802                  *
2803                  * In the case there is 0 byte write, or error case, since
2804                  * VFS direct IO won't invoke the end_io call back function,
2805                  * we need to free the end_io structure here.
2806                  */
2807                 if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
2808                         ext4_free_io_end(iocb->private);
2809                         iocb->private = NULL;
2810                 } else if (ret > 0 && ext4_test_inode_state(inode,
2811                                                 EXT4_STATE_DIO_UNWRITTEN)) {
2812                         int err;
2813                         /*
2814                          * for non AIO case, since the IO is already
2815                          * completed, we could do the conversion right here
2816                          */
2817                         err = ext4_convert_unwritten_extents(inode,
2818                                                              offset, ret);
2819                         if (err < 0)
2820                                 ret = err;
2821                         ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
2822                 }
2823                 return ret;
2824         }
2825
2826         /* for write the the end of file case, we fall back to old way */
2827         return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
2828 }
2829
2830 static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
2831                               const struct iovec *iov, loff_t offset,
2832                               unsigned long nr_segs)
2833 {
2834         struct file *file = iocb->ki_filp;
2835         struct inode *inode = file->f_mapping->host;
2836         ssize_t ret;
2837
2838         trace_ext4_direct_IO_enter(inode, offset, iov_length(iov, nr_segs), rw);
2839         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
2840                 ret = ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
2841         else
2842                 ret = ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
2843         trace_ext4_direct_IO_exit(inode, offset,
2844                                 iov_length(iov, nr_segs), rw, ret);
2845         return ret;
2846 }
2847
2848 /*
2849  * Pages can be marked dirty completely asynchronously from ext4's journalling
2850  * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
2851  * much here because ->set_page_dirty is called under VFS locks.  The page is
2852  * not necessarily locked.
2853  *
2854  * We cannot just dirty the page and leave attached buffers clean, because the
2855  * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
2856  * or jbddirty because all the journalling code will explode.
2857  *
2858  * So what we do is to mark the page "pending dirty" and next time writepage
2859  * is called, propagate that into the buffers appropriately.
2860  */
2861 static int ext4_journalled_set_page_dirty(struct page *page)
2862 {
2863         SetPageChecked(page);
2864         return __set_page_dirty_nobuffers(page);
2865 }
2866
2867 static const struct address_space_operations ext4_ordered_aops = {
2868         .readpage               = ext4_readpage,
2869         .readpages              = ext4_readpages,
2870         .writepage              = ext4_writepage,
2871         .write_begin            = ext4_write_begin,
2872         .write_end              = ext4_ordered_write_end,
2873         .bmap                   = ext4_bmap,
2874         .invalidatepage         = ext4_invalidatepage,
2875         .releasepage            = ext4_releasepage,
2876         .direct_IO              = ext4_direct_IO,
2877         .migratepage            = buffer_migrate_page,
2878         .is_partially_uptodate  = block_is_partially_uptodate,
2879         .error_remove_page      = generic_error_remove_page,
2880 };
2881
2882 static const struct address_space_operations ext4_writeback_aops = {
2883         .readpage               = ext4_readpage,
2884         .readpages              = ext4_readpages,
2885         .writepage              = ext4_writepage,
2886         .write_begin            = ext4_write_begin,
2887         .write_end              = ext4_writeback_write_end,
2888         .bmap                   = ext4_bmap,
2889         .invalidatepage         = ext4_invalidatepage,
2890         .releasepage            = ext4_releasepage,
2891         .direct_IO              = ext4_direct_IO,
2892         .migratepage            = buffer_migrate_page,
2893         .is_partially_uptodate  = block_is_partially_uptodate,
2894         .error_remove_page      = generic_error_remove_page,
2895 };
2896
2897 static const struct address_space_operations ext4_journalled_aops = {
2898         .readpage               = ext4_readpage,
2899         .readpages              = ext4_readpages,
2900         .writepage              = ext4_writepage,
2901         .write_begin            = ext4_write_begin,
2902         .write_end              = ext4_journalled_write_end,
2903         .set_page_dirty         = ext4_journalled_set_page_dirty,
2904         .bmap                   = ext4_bmap,
2905         .invalidatepage         = ext4_invalidatepage,
2906         .releasepage            = ext4_releasepage,
2907         .is_partially_uptodate  = block_is_partially_uptodate,
2908         .error_remove_page      = generic_error_remove_page,
2909 };
2910
2911 static const struct address_space_operations ext4_da_aops = {
2912         .readpage               = ext4_readpage,
2913         .readpages              = ext4_readpages,
2914         .writepage              = ext4_writepage,
2915         .writepages             = ext4_da_writepages,
2916         .write_begin            = ext4_da_write_begin,
2917         .write_end              = ext4_da_write_end,
2918         .bmap                   = ext4_bmap,
2919         .invalidatepage         = ext4_da_invalidatepage,
2920         .releasepage            = ext4_releasepage,
2921         .direct_IO              = ext4_direct_IO,
2922         .migratepage            = buffer_migrate_page,
2923         .is_partially_uptodate  = block_is_partially_uptodate,
2924         .error_remove_page      = generic_error_remove_page,
2925 };
2926
2927 void ext4_set_aops(struct inode *inode)
2928 {
2929         if (ext4_should_order_data(inode) &&
2930                 test_opt(inode->i_sb, DELALLOC))
2931                 inode->i_mapping->a_ops = &ext4_da_aops;
2932         else if (ext4_should_order_data(inode))
2933                 inode->i_mapping->a_ops = &ext4_ordered_aops;
2934         else if (ext4_should_writeback_data(inode) &&
2935                  test_opt(inode->i_sb, DELALLOC))
2936                 inode->i_mapping->a_ops = &ext4_da_aops;
2937         else if (ext4_should_writeback_data(inode))
2938                 inode->i_mapping->a_ops = &ext4_writeback_aops;
2939         else
2940                 inode->i_mapping->a_ops = &ext4_journalled_aops;
2941 }
2942
2943 /*
2944  * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
2945  * up to the end of the block which corresponds to `from'.
2946  * This required during truncate. We need to physically zero the tail end
2947  * of that block so it doesn't yield old data if the file is later grown.
2948  */
2949 int ext4_block_truncate_page(handle_t *handle,
2950                 struct address_space *mapping, loff_t from)
2951 {
2952         unsigned offset = from & (PAGE_CACHE_SIZE-1);
2953         unsigned length;
2954         unsigned blocksize;
2955         struct inode *inode = mapping->host;
2956
2957         blocksize = inode->i_sb->s_blocksize;
2958         length = blocksize - (offset & (blocksize - 1));
2959
2960         return ext4_block_zero_page_range(handle, mapping, from, length);
2961 }
2962
2963 /*
2964  * ext4_block_zero_page_range() zeros out a mapping of length 'length'
2965  * starting from file offset 'from'.  The range to be zero'd must
2966  * be contained with in one block.  If the specified range exceeds
2967  * the end of the block it will be shortened to end of the block
2968  * that cooresponds to 'from'
2969  */
2970 int ext4_block_zero_page_range(handle_t *handle,
2971                 struct address_space *mapping, loff_t from, loff_t length)
2972 {
2973         ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
2974         unsigned offset = from & (PAGE_CACHE_SIZE-1);
2975         unsigned blocksize, max, pos;
2976         ext4_lblk_t iblock;
2977         struct inode *inode = mapping->host;
2978         struct buffer_head *bh;
2979         struct page *page;
2980         int err = 0;
2981
2982         page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT,
2983                                    mapping_gfp_mask(mapping) & ~__GFP_FS);
2984         if (!page)
2985                 return -EINVAL;
2986
2987         blocksize = inode->i_sb->s_blocksize;
2988         max = blocksize - (offset & (blocksize - 1));
2989
2990         /*
2991          * correct length if it does not fall between
2992          * 'from' and the end of the block
2993          */
2994         if (length > max || length < 0)
2995                 length = max;
2996
2997         iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
2998
2999         if (!page_has_buffers(page))
3000                 create_empty_buffers(page, blocksize, 0);
3001
3002         /* Find the buffer that contains "offset" */
3003         bh = page_buffers(page);
3004         pos = blocksize;
3005         while (offset >= pos) {
3006                 bh = bh->b_this_page;
3007                 iblock++;
3008                 pos += blocksize;
3009         }
3010
3011         err = 0;
3012         if (buffer_freed(bh)) {
3013                 BUFFER_TRACE(bh, "freed: skip");
3014                 goto unlock;
3015         }
3016
3017         if (!buffer_mapped(bh)) {
3018                 BUFFER_TRACE(bh, "unmapped");
3019                 ext4_get_block(inode, iblock, bh, 0);
3020                 /* unmapped? It's a hole - nothing to do */
3021                 if (!buffer_mapped(bh)) {
3022                         BUFFER_TRACE(bh, "still unmapped");
3023                         goto unlock;
3024                 }
3025         }
3026
3027         /* Ok, it's mapped. Make sure it's up-to-date */
3028         if (PageUptodate(page))
3029                 set_buffer_uptodate(bh);
3030
3031         if (!buffer_uptodate(bh)) {
3032                 err = -EIO;
3033                 ll_rw_block(READ, 1, &bh);
3034                 wait_on_buffer(bh);
3035                 /* Uhhuh. Read error. Complain and punt. */
3036                 if (!buffer_uptodate(bh))
3037                         goto unlock;
3038         }
3039
3040         if (ext4_should_journal_data(inode)) {
3041                 BUFFER_TRACE(bh, "get write access");
3042                 err = ext4_journal_get_write_access(handle, bh);
3043                 if (err)
3044                         goto unlock;
3045         }
3046
3047         zero_user(page, offset, length);
3048
3049         BUFFER_TRACE(bh, "zeroed end of block");
3050
3051         err = 0;
3052         if (ext4_should_journal_data(inode)) {
3053                 err = ext4_handle_dirty_metadata(handle, inode, bh);
3054         } else {
3055                 if (ext4_should_order_data(inode) && EXT4_I(inode)->jinode)
3056                         err = ext4_jbd2_file_inode(handle, inode);
3057                 mark_buffer_dirty(bh);
3058         }
3059
3060 unlock:
3061         unlock_page(page);
3062         page_cache_release(page);
3063         return err;
3064 }
3065
3066 int ext4_can_truncate(struct inode *inode)
3067 {
3068         if (S_ISREG(inode->i_mode))
3069                 return 1;
3070         if (S_ISDIR(inode->i_mode))
3071                 return 1;
3072         if (S_ISLNK(inode->i_mode))
3073                 return !ext4_inode_is_fast_symlink(inode);
3074         return 0;
3075 }
3076
3077 /*
3078  * ext4_punch_hole: punches a hole in a file by releaseing the blocks
3079  * associated with the given offset and length
3080  *
3081  * @inode:  File inode
3082  * @offset: The offset where the hole will begin
3083  * @len:    The length of the hole
3084  *
3085  * Returns: 0 on sucess or negative on failure
3086  */
3087
3088 int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
3089 {
3090         struct inode *inode = file->f_path.dentry->d_inode;
3091         if (!S_ISREG(inode->i_mode))
3092                 return -ENOTSUPP;
3093
3094         if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
3095                 /* TODO: Add support for non extent hole punching */
3096                 return -ENOTSUPP;
3097         }
3098
3099         return ext4_ext_punch_hole(file, offset, length);
3100 }
3101
3102 /*
3103  * ext4_truncate()
3104  *
3105  * We block out ext4_get_block() block instantiations across the entire
3106  * transaction, and VFS/VM ensures that ext4_truncate() cannot run
3107  * simultaneously on behalf of the same inode.
3108  *
3109  * As we work through the truncate and commmit bits of it to the journal there
3110  * is one core, guiding principle: the file's tree must always be consistent on
3111  * disk.  We must be able to restart the truncate after a crash.
3112  *
3113  * The file's tree may be transiently inconsistent in memory (although it
3114  * probably isn't), but whenever we close off and commit a journal transaction,
3115  * the contents of (the filesystem + the journal) must be consistent and
3116  * restartable.  It's pretty simple, really: bottom up, right to left (although
3117  * left-to-right works OK too).
3118  *
3119  * Note that at recovery time, journal replay occurs *before* the restart of
3120  * truncate against the orphan inode list.
3121  *
3122  * The committed inode has the new, desired i_size (which is the same as
3123  * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
3124  * that this inode's truncate did not complete and it will again call
3125  * ext4_truncate() to have another go.  So there will be instantiated blocks
3126  * to the right of the truncation point in a crashed ext4 filesystem.  But
3127  * that's fine - as long as they are linked from the inode, the post-crash
3128  * ext4_truncate() run will find them and release them.
3129  */
3130 void ext4_truncate(struct inode *inode)
3131 {
3132         trace_ext4_truncate_enter(inode);
3133
3134         if (!ext4_can_truncate(inode))
3135                 return;
3136
3137         ext4_clear_inode_flag(inode, EXT4_INODE_EOFBLOCKS);
3138
3139         if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
3140                 ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
3141
3142         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
3143                 ext4_ext_truncate(inode);
3144         else
3145                 ext4_ind_truncate(inode);
3146
3147         trace_ext4_truncate_exit(inode);
3148 }
3149
3150 /*
3151  * ext4_get_inode_loc returns with an extra refcount against the inode's
3152  * underlying buffer_head on success. If 'in_mem' is true, we have all
3153  * data in memory that is needed to recreate the on-disk version of this
3154  * inode.
3155  */
3156 static int __ext4_get_inode_loc(struct inode *inode,
3157                                 struct ext4_iloc *iloc, int in_mem)
3158 {
3159         struct ext4_group_desc  *gdp;
3160         struct buffer_head      *bh;
3161         struct super_block      *sb = inode->i_sb;
3162         ext4_fsblk_t            block;
3163         int                     inodes_per_block, inode_offset;
3164
3165         iloc->bh = NULL;
3166         if (!ext4_valid_inum(sb, inode->i_ino))
3167                 return -EIO;
3168
3169         iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);
3170         gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
3171         if (!gdp)
3172                 return -EIO;
3173
3174         /*
3175          * Figure out the offset within the block group inode table
3176          */
3177         inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
3178         inode_offset = ((inode->i_ino - 1) %
3179                         EXT4_INODES_PER_GROUP(sb));
3180         block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
3181         iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
3182
3183         bh = sb_getblk(sb, block);
3184         if (!bh) {
3185                 EXT4_ERROR_INODE_BLOCK(inode, block,
3186                                        "unable to read itable block");
3187                 return -EIO;
3188         }
3189         if (!buffer_uptodate(bh)) {
3190                 lock_buffer(bh);
3191
3192                 /*
3193                  * If the buffer has the write error flag, we have failed
3194                  * to write out another inode in the same block.  In this
3195                  * case, we don't have to read the block because we may
3196                  * read the old inode data successfully.
3197                  */
3198                 if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
3199                         set_buffer_uptodate(bh);
3200
3201                 if (buffer_uptodate(bh)) {
3202                         /* someone brought it uptodate while we waited */
3203                         unlock_buffer(bh);
3204                         goto has_buffer;
3205                 }
3206
3207                 /*
3208                  * If we have all information of the inode in memory and this
3209                  * is the only valid inode in the block, we need not read the
3210                  * block.
3211                  */
3212                 if (in_mem) {
3213                         struct buffer_head *bitmap_bh;
3214                         int i, start;
3215
3216                         start = inode_offset & ~(inodes_per_block - 1);
3217
3218                         /* Is the inode bitmap in cache? */
3219                         bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
3220                         if (!bitmap_bh)
3221                                 goto make_io;
3222