1cfbe857ba27216c03243c6eea5b07ab9d72b1f4
[linux-2.6.git] / fs / reiserfs / file.c
1 /*
2  * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
3  */
4
5 #include <linux/time.h>
6 #include <linux/reiserfs_fs.h>
7 #include <linux/reiserfs_acl.h>
8 #include <linux/reiserfs_xattr.h>
9 #include <linux/smp_lock.h>
10 #include <asm/uaccess.h>
11 #include <linux/pagemap.h>
12 #include <linux/swap.h>
13 #include <linux/writeback.h>
14 #include <linux/blkdev.h>
15 #include <linux/buffer_head.h>
16 #include <linux/quotaops.h>
17
18 /*
19 ** We pack the tails of files on file close, not at the time they are written.
20 ** This implies an unnecessary copy of the tail and an unnecessary indirect item
21 ** insertion/balancing, for files that are written in one write.
22 ** It avoids unnecessary tail packings (balances) for files that are written in
23 ** multiple writes and are small enough to have tails.
24 ** 
25 ** file_release is called by the VFS layer when the file is closed.  If
26 ** this is the last open file descriptor, and the file
27 ** small enough to have a tail, and the tail is currently in an
28 ** unformatted node, the tail is converted back into a direct item.
29 ** 
30 ** We use reiserfs_truncate_file to pack the tail, since it already has
31 ** all the conditions coded.  
32 */
33 static int reiserfs_file_release(struct inode *inode, struct file *filp)
34 {
35
36         struct reiserfs_transaction_handle th;
37         int err;
38         int jbegin_failure = 0;
39
40         if (!S_ISREG(inode->i_mode))
41                 BUG();
42
43         /* fast out for when nothing needs to be done */
44         if ((atomic_read(&inode->i_count) > 1 ||
45              !(REISERFS_I(inode)->i_flags & i_pack_on_close_mask) ||
46              !tail_has_to_be_packed(inode)) &&
47             REISERFS_I(inode)->i_prealloc_count <= 0) {
48                 return 0;
49         }
50
51         mutex_lock(&inode->i_mutex);
52         reiserfs_write_lock(inode->i_sb);
53         /* freeing preallocation only involves relogging blocks that
54          * are already in the current transaction.  preallocation gets
55          * freed at the end of each transaction, so it is impossible for
56          * us to log any additional blocks (including quota blocks)
57          */
58         err = journal_begin(&th, inode->i_sb, 1);
59         if (err) {
60                 /* uh oh, we can't allow the inode to go away while there
61                  * is still preallocation blocks pending.  Try to join the
62                  * aborted transaction
63                  */
64                 jbegin_failure = err;
65                 err = journal_join_abort(&th, inode->i_sb, 1);
66
67                 if (err) {
68                         /* hmpf, our choices here aren't good.  We can pin the inode
69                          * which will disallow unmount from every happening, we can
70                          * do nothing, which will corrupt random memory on unmount,
71                          * or we can forcibly remove the file from the preallocation
72                          * list, which will leak blocks on disk.  Lets pin the inode
73                          * and let the admin know what is going on.
74                          */
75                         igrab(inode);
76                         reiserfs_warning(inode->i_sb,
77                                          "pinning inode %lu because the "
78                                          "preallocation can't be freed");
79                         goto out;
80                 }
81         }
82         reiserfs_update_inode_transaction(inode);
83
84 #ifdef REISERFS_PREALLOCATE
85         reiserfs_discard_prealloc(&th, inode);
86 #endif
87         err = journal_end(&th, inode->i_sb, 1);
88
89         /* copy back the error code from journal_begin */
90         if (!err)
91                 err = jbegin_failure;
92
93         if (!err && atomic_read(&inode->i_count) <= 1 &&
94             (REISERFS_I(inode)->i_flags & i_pack_on_close_mask) &&
95             tail_has_to_be_packed(inode)) {
96                 /* if regular file is released by last holder and it has been
97                    appended (we append by unformatted node only) or its direct
98                    item(s) had to be converted, then it may have to be
99                    indirect2direct converted */
100                 err = reiserfs_truncate_file(inode, 0);
101         }
102       out:
103         mutex_unlock(&inode->i_mutex);
104         reiserfs_write_unlock(inode->i_sb);
105         return err;
106 }
107
108 static void reiserfs_vfs_truncate_file(struct inode *inode)
109 {
110         reiserfs_truncate_file(inode, 1);
111 }
112
113 /* Sync a reiserfs file. */
114
115 /*
116  * FIXME: sync_mapping_buffers() never has anything to sync.  Can
117  * be removed...
118  */
119
120 static int reiserfs_sync_file(struct file *p_s_filp,
121                               struct dentry *p_s_dentry, int datasync)
122 {
123         struct inode *p_s_inode = p_s_dentry->d_inode;
124         int n_err;
125         int barrier_done;
126
127         if (!S_ISREG(p_s_inode->i_mode))
128                 BUG();
129         n_err = sync_mapping_buffers(p_s_inode->i_mapping);
130         reiserfs_write_lock(p_s_inode->i_sb);
131         barrier_done = reiserfs_commit_for_inode(p_s_inode);
132         reiserfs_write_unlock(p_s_inode->i_sb);
133         if (barrier_done != 1 && reiserfs_barrier_flush(p_s_inode->i_sb))
134                 blkdev_issue_flush(p_s_inode->i_sb->s_bdev, NULL);
135         if (barrier_done < 0)
136                 return barrier_done;
137         return (n_err < 0) ? -EIO : 0;
138 }
139
140 /* I really do not want to play with memory shortage right now, so
141    to simplify the code, we are not going to write more than this much pages at
142    a time. This still should considerably improve performance compared to 4k
143    at a time case. This is 32 pages of 4k size. */
144 #define REISERFS_WRITE_PAGES_AT_A_TIME (128 * 1024) / PAGE_CACHE_SIZE
145
146 /* Allocates blocks for a file to fulfil write request.
147    Maps all unmapped but prepared pages from the list.
148    Updates metadata with newly allocated blocknumbers as needed */
149 static int reiserfs_allocate_blocks_for_region(struct reiserfs_transaction_handle *th, struct inode *inode,     /* Inode we work with */
150                                                loff_t pos,      /* Writing position */
151                                                int num_pages,   /* number of pages write going
152                                                                    to touch */
153                                                int write_bytes, /* amount of bytes to write */
154                                                struct page **prepared_pages,    /* array of
155                                                                                    prepared pages
156                                                                                  */
157                                                int blocks_to_allocate   /* Amount of blocks we
158                                                                            need to allocate to
159                                                                            fit the data into file
160                                                                          */
161     )
162 {
163         struct cpu_key key;     // cpu key of item that we are going to deal with
164         struct item_head *ih;   // pointer to item head that we are going to deal with
165         struct buffer_head *bh; // Buffer head that contains items that we are going to deal with
166         __le32 *item;           // pointer to item we are going to deal with
167         INITIALIZE_PATH(path);  // path to item, that we are going to deal with.
168         b_blocknr_t *allocated_blocks;  // Pointer to a place where allocated blocknumbers would be stored.
169         reiserfs_blocknr_hint_t hint;   // hint structure for block allocator.
170         size_t res;             // return value of various functions that we call.
171         int curr_block;         // current block used to keep track of unmapped blocks.
172         int i;                  // loop counter
173         int itempos;            // position in item
174         unsigned int from = (pos & (PAGE_CACHE_SIZE - 1));      // writing position in
175         // first page
176         unsigned int to = ((pos + write_bytes - 1) & (PAGE_CACHE_SIZE - 1)) + 1;        /* last modified byte offset in last page */
177         __u64 hole_size;        // amount of blocks for a file hole, if it needed to be created.
178         int modifying_this_item = 0;    // Flag for items traversal code to keep track
179         // of the fact that we already prepared
180         // current block for journal
181         int will_prealloc = 0;
182         RFALSE(!blocks_to_allocate,
183                "green-9004: tried to allocate zero blocks?");
184
185         /* only preallocate if this is a small write */
186         if (REISERFS_I(inode)->i_prealloc_count ||
187             (!(write_bytes & (inode->i_sb->s_blocksize - 1)) &&
188              blocks_to_allocate <
189              REISERFS_SB(inode->i_sb)->s_alloc_options.preallocsize))
190                 will_prealloc =
191                     REISERFS_SB(inode->i_sb)->s_alloc_options.preallocsize;
192
193         allocated_blocks = kmalloc((blocks_to_allocate + will_prealloc) *
194                                    sizeof(b_blocknr_t), GFP_NOFS);
195         if (!allocated_blocks)
196                 return -ENOMEM;
197
198         /* First we compose a key to point at the writing position, we want to do
199            that outside of any locking region. */
200         make_cpu_key(&key, inode, pos + 1, TYPE_ANY, 3 /*key length */ );
201
202         /* If we came here, it means we absolutely need to open a transaction,
203            since we need to allocate some blocks */
204         reiserfs_write_lock(inode->i_sb);       // Journaling stuff and we need that.
205         res = journal_begin(th, inode->i_sb, JOURNAL_PER_BALANCE_CNT * 3 + 1 + 2 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb));   // Wish I know if this number enough
206         if (res)
207                 goto error_exit;
208         reiserfs_update_inode_transaction(inode);
209
210         /* Look for the in-tree position of our write, need path for block allocator */
211         res = search_for_position_by_key(inode->i_sb, &key, &path);
212         if (res == IO_ERROR) {
213                 res = -EIO;
214                 goto error_exit;
215         }
216
217         /* Allocate blocks */
218         /* First fill in "hint" structure for block allocator */
219         hint.th = th;           // transaction handle.
220         hint.path = &path;      // Path, so that block allocator can determine packing locality or whatever it needs to determine.
221         hint.inode = inode;     // Inode is needed by block allocator too.
222         hint.search_start = 0;  // We have no hint on where to search free blocks for block allocator.
223         hint.key = key.on_disk_key;     // on disk key of file.
224         hint.block = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);    // Number of disk blocks this file occupies already.
225         hint.formatted_node = 0;        // We are allocating blocks for unformatted node.
226         hint.preallocate = will_prealloc;
227
228         /* Call block allocator to allocate blocks */
229         res =
230             reiserfs_allocate_blocknrs(&hint, allocated_blocks,
231                                        blocks_to_allocate, blocks_to_allocate);
232         if (res != CARRY_ON) {
233                 if (res == NO_DISK_SPACE) {
234                         /* We flush the transaction in case of no space. This way some
235                            blocks might become free */
236                         SB_JOURNAL(inode->i_sb)->j_must_wait = 1;
237                         res = restart_transaction(th, inode, &path);
238                         if (res)
239                                 goto error_exit;
240
241                         /* We might have scheduled, so search again */
242                         res =
243                             search_for_position_by_key(inode->i_sb, &key,
244                                                        &path);
245                         if (res == IO_ERROR) {
246                                 res = -EIO;
247                                 goto error_exit;
248                         }
249
250                         /* update changed info for hint structure. */
251                         res =
252                             reiserfs_allocate_blocknrs(&hint, allocated_blocks,
253                                                        blocks_to_allocate,
254                                                        blocks_to_allocate);
255                         if (res != CARRY_ON) {
256                                 res = res == QUOTA_EXCEEDED ? -EDQUOT : -ENOSPC;
257                                 pathrelse(&path);
258                                 goto error_exit;
259                         }
260                 } else {
261                         res = res == QUOTA_EXCEEDED ? -EDQUOT : -ENOSPC;
262                         pathrelse(&path);
263                         goto error_exit;
264                 }
265         }
266 #ifdef __BIG_ENDIAN
267         // Too bad, I have not found any way to convert a given region from
268         // cpu format to little endian format
269         {
270                 int i;
271                 for (i = 0; i < blocks_to_allocate; i++)
272                         allocated_blocks[i] = cpu_to_le32(allocated_blocks[i]);
273         }
274 #endif
275
276         /* Blocks allocating well might have scheduled and tree might have changed,
277            let's search the tree again */
278         /* find where in the tree our write should go */
279         res = search_for_position_by_key(inode->i_sb, &key, &path);
280         if (res == IO_ERROR) {
281                 res = -EIO;
282                 goto error_exit_free_blocks;
283         }
284
285         bh = get_last_bh(&path);        // Get a bufferhead for last element in path.
286         ih = get_ih(&path);     // Get a pointer to last item head in path.
287         item = get_item(&path); // Get a pointer to last item in path
288
289         /* Let's see what we have found */
290         if (res != POSITION_FOUND) {    /* position not found, this means that we
291                                            might need to append file with holes
292                                            first */
293                 // Since we are writing past the file's end, we need to find out if
294                 // there is a hole that needs to be inserted before our writing
295                 // position, and how many blocks it is going to cover (we need to
296                 //  populate pointers to file blocks representing the hole with zeros)
297
298                 {
299                         int item_offset = 1;
300                         /*
301                          * if ih is stat data, its offset is 0 and we don't want to
302                          * add 1 to pos in the hole_size calculation
303                          */
304                         if (is_statdata_le_ih(ih))
305                                 item_offset = 0;
306                         hole_size = (pos + item_offset -
307                                      (le_key_k_offset
308                                       (get_inode_item_key_version(inode),
309                                        &(ih->ih_key)) + op_bytes_number(ih,
310                                                                         inode->
311                                                                         i_sb->
312                                                                         s_blocksize)))
313                             >> inode->i_sb->s_blocksize_bits;
314                 }
315
316                 if (hole_size > 0) {
317                         int to_paste = min_t(__u64, hole_size, MAX_ITEM_LEN(inode->i_sb->s_blocksize) / UNFM_P_SIZE);   // How much data to insert first time.
318                         /* area filled with zeroes, to supply as list of zero blocknumbers
319                            We allocate it outside of loop just in case loop would spin for
320                            several iterations. */
321                         char *zeros = kmalloc(to_paste * UNFM_P_SIZE, GFP_ATOMIC);      // We cannot insert more than MAX_ITEM_LEN bytes anyway.
322                         if (!zeros) {
323                                 res = -ENOMEM;
324                                 goto error_exit_free_blocks;
325                         }
326                         memset(zeros, 0, to_paste * UNFM_P_SIZE);
327                         do {
328                                 to_paste =
329                                     min_t(__u64, hole_size,
330                                           MAX_ITEM_LEN(inode->i_sb->
331                                                        s_blocksize) /
332                                           UNFM_P_SIZE);
333                                 if (is_indirect_le_ih(ih)) {
334                                         /* Ok, there is existing indirect item already. Need to append it */
335                                         /* Calculate position past inserted item */
336                                         make_cpu_key(&key, inode,
337                                                      le_key_k_offset
338                                                      (get_inode_item_key_version
339                                                       (inode),
340                                                       &(ih->ih_key)) +
341                                                      op_bytes_number(ih,
342                                                                      inode->
343                                                                      i_sb->
344                                                                      s_blocksize),
345                                                      TYPE_INDIRECT, 3);
346                                         res =
347                                             reiserfs_paste_into_item(th, &path,
348                                                                      &key,
349                                                                      inode,
350                                                                      (char *)
351                                                                      zeros,
352                                                                      UNFM_P_SIZE
353                                                                      *
354                                                                      to_paste);
355                                         if (res) {
356                                                 kfree(zeros);
357                                                 goto error_exit_free_blocks;
358                                         }
359                                 } else if (is_statdata_le_ih(ih)) {
360                                         /* No existing item, create it */
361                                         /* item head for new item */
362                                         struct item_head ins_ih;
363
364                                         /* create a key for our new item */
365                                         make_cpu_key(&key, inode, 1,
366                                                      TYPE_INDIRECT, 3);
367
368                                         /* Create new item head for our new item */
369                                         make_le_item_head(&ins_ih, &key,
370                                                           key.version, 1,
371                                                           TYPE_INDIRECT,
372                                                           to_paste *
373                                                           UNFM_P_SIZE,
374                                                           0 /* free space */ );
375
376                                         /* Find where such item should live in the tree */
377                                         res =
378                                             search_item(inode->i_sb, &key,
379                                                         &path);
380                                         if (res != ITEM_NOT_FOUND) {
381                                                 /* item should not exist, otherwise we have error */
382                                                 if (res != -ENOSPC) {
383                                                         reiserfs_warning(inode->
384                                                                          i_sb,
385                                                                          "green-9008: search_by_key (%K) returned %d",
386                                                                          &key,
387                                                                          res);
388                                                 }
389                                                 res = -EIO;
390                                                 kfree(zeros);
391                                                 goto error_exit_free_blocks;
392                                         }
393                                         res =
394                                             reiserfs_insert_item(th, &path,
395                                                                  &key, &ins_ih,
396                                                                  inode,
397                                                                  (char *)zeros);
398                                 } else {
399                                         reiserfs_panic(inode->i_sb,
400                                                        "green-9011: Unexpected key type %K\n",
401                                                        &key);
402                                 }
403                                 if (res) {
404                                         kfree(zeros);
405                                         goto error_exit_free_blocks;
406                                 }
407                                 /* Now we want to check if transaction is too full, and if it is
408                                    we restart it. This will also free the path. */
409                                 if (journal_transaction_should_end
410                                     (th, th->t_blocks_allocated)) {
411                                         res =
412                                             restart_transaction(th, inode,
413                                                                 &path);
414                                         if (res) {
415                                                 pathrelse(&path);
416                                                 kfree(zeros);
417                                                 goto error_exit;
418                                         }
419                                 }
420
421                                 /* Well, need to recalculate path and stuff */
422                                 set_cpu_key_k_offset(&key,
423                                                      cpu_key_k_offset(&key) +
424                                                      (to_paste << inode->
425                                                       i_blkbits));
426                                 res =
427                                     search_for_position_by_key(inode->i_sb,
428                                                                &key, &path);
429                                 if (res == IO_ERROR) {
430                                         res = -EIO;
431                                         kfree(zeros);
432                                         goto error_exit_free_blocks;
433                                 }
434                                 bh = get_last_bh(&path);
435                                 ih = get_ih(&path);
436                                 item = get_item(&path);
437                                 hole_size -= to_paste;
438                         } while (hole_size);
439                         kfree(zeros);
440                 }
441         }
442         // Go through existing indirect items first
443         // replace all zeroes with blocknumbers from list
444         // Note that if no corresponding item was found, by previous search,
445         // it means there are no existing in-tree representation for file area
446         // we are going to overwrite, so there is nothing to scan through for holes.
447         for (curr_block = 0, itempos = path.pos_in_item;
448              curr_block < blocks_to_allocate && res == POSITION_FOUND;) {
449               retry:
450
451                 if (itempos >= ih_item_len(ih) / UNFM_P_SIZE) {
452                         /* We run out of data in this indirect item, let's look for another
453                            one. */
454                         /* First if we are already modifying current item, log it */
455                         if (modifying_this_item) {
456                                 journal_mark_dirty(th, inode->i_sb, bh);
457                                 modifying_this_item = 0;
458                         }
459                         /* Then set the key to look for a new indirect item (offset of old
460                            item is added to old item length */
461                         set_cpu_key_k_offset(&key,
462                                              le_key_k_offset
463                                              (get_inode_item_key_version(inode),
464                                               &(ih->ih_key)) +
465                                              op_bytes_number(ih,
466                                                              inode->i_sb->
467                                                              s_blocksize));
468                         /* Search ofor position of new key in the tree. */
469                         res =
470                             search_for_position_by_key(inode->i_sb, &key,
471                                                        &path);
472                         if (res == IO_ERROR) {
473                                 res = -EIO;
474                                 goto error_exit_free_blocks;
475                         }
476                         bh = get_last_bh(&path);
477                         ih = get_ih(&path);
478                         item = get_item(&path);
479                         itempos = path.pos_in_item;
480                         continue;       // loop to check all kinds of conditions and so on.
481                 }
482                 /* Ok, we have correct position in item now, so let's see if it is
483                    representing file hole (blocknumber is zero) and fill it if needed */
484                 if (!item[itempos]) {
485                         /* Ok, a hole. Now we need to check if we already prepared this
486                            block to be journaled */
487                         while (!modifying_this_item) {  // loop until succeed
488                                 /* Well, this item is not journaled yet, so we must prepare
489                                    it for journal first, before we can change it */
490                                 struct item_head tmp_ih;        // We copy item head of found item,
491                                 // here to detect if fs changed under
492                                 // us while we were preparing for
493                                 // journal.
494                                 int fs_gen;     // We store fs generation here to find if someone
495                                 // changes fs under our feet
496
497                                 copy_item_head(&tmp_ih, ih);    // Remember itemhead
498                                 fs_gen = get_generation(inode->i_sb);   // remember fs generation
499                                 reiserfs_prepare_for_journal(inode->i_sb, bh, 1);       // Prepare a buffer within which indirect item is stored for changing.
500                                 if (fs_changed(fs_gen, inode->i_sb)
501                                     && item_moved(&tmp_ih, &path)) {
502                                         // Sigh, fs was changed under us, we need to look for new
503                                         // location of item we are working with
504
505                                         /* unmark prepaerd area as journaled and search for it's
506                                            new position */
507                                         reiserfs_restore_prepared_buffer(inode->
508                                                                          i_sb,
509                                                                          bh);
510                                         res =
511                                             search_for_position_by_key(inode->
512                                                                        i_sb,
513                                                                        &key,
514                                                                        &path);
515                                         if (res == IO_ERROR) {
516                                                 res = -EIO;
517                                                 goto error_exit_free_blocks;
518                                         }
519                                         bh = get_last_bh(&path);
520                                         ih = get_ih(&path);
521                                         item = get_item(&path);
522                                         itempos = path.pos_in_item;
523                                         goto retry;
524                                 }
525                                 modifying_this_item = 1;
526                         }
527                         item[itempos] = allocated_blocks[curr_block];   // Assign new block
528                         curr_block++;
529                 }
530                 itempos++;
531         }
532
533         if (modifying_this_item) {      // We need to log last-accessed block, if it
534                 // was modified, but not logged yet.
535                 journal_mark_dirty(th, inode->i_sb, bh);
536         }
537
538         if (curr_block < blocks_to_allocate) {
539                 // Oh, well need to append to indirect item, or to create indirect item
540                 // if there weren't any
541                 if (is_indirect_le_ih(ih)) {
542                         // Existing indirect item - append. First calculate key for append
543                         // position. We do not need to recalculate path as it should
544                         // already point to correct place.
545                         make_cpu_key(&key, inode,
546                                      le_key_k_offset(get_inode_item_key_version
547                                                      (inode),
548                                                      &(ih->ih_key)) +
549                                      op_bytes_number(ih,
550                                                      inode->i_sb->s_blocksize),
551                                      TYPE_INDIRECT, 3);
552                         res =
553                             reiserfs_paste_into_item(th, &path, &key, inode,
554                                                      (char *)(allocated_blocks +
555                                                               curr_block),
556                                                      UNFM_P_SIZE *
557                                                      (blocks_to_allocate -
558                                                       curr_block));
559                         if (res) {
560                                 goto error_exit_free_blocks;
561                         }
562                 } else if (is_statdata_le_ih(ih)) {
563                         // Last found item was statdata. That means we need to create indirect item.
564                         struct item_head ins_ih;        /* itemhead for new item */
565
566                         /* create a key for our new item */
567                         make_cpu_key(&key, inode, 1, TYPE_INDIRECT, 3); // Position one,
568                         // because that's
569                         // where first
570                         // indirect item
571                         // begins
572                         /* Create new item head for our new item */
573                         make_le_item_head(&ins_ih, &key, key.version, 1,
574                                           TYPE_INDIRECT,
575                                           (blocks_to_allocate -
576                                            curr_block) * UNFM_P_SIZE,
577                                           0 /* free space */ );
578                         /* Find where such item should live in the tree */
579                         res = search_item(inode->i_sb, &key, &path);
580                         if (res != ITEM_NOT_FOUND) {
581                                 /* Well, if we have found such item already, or some error
582                                    occured, we need to warn user and return error */
583                                 if (res != -ENOSPC) {
584                                         reiserfs_warning(inode->i_sb,
585                                                          "green-9009: search_by_key (%K) "
586                                                          "returned %d", &key,
587                                                          res);
588                                 }
589                                 res = -EIO;
590                                 goto error_exit_free_blocks;
591                         }
592                         /* Insert item into the tree with the data as its body */
593                         res =
594                             reiserfs_insert_item(th, &path, &key, &ins_ih,
595                                                  inode,
596                                                  (char *)(allocated_blocks +
597                                                           curr_block));
598                 } else {
599                         reiserfs_panic(inode->i_sb,
600                                        "green-9010: unexpected item type for key %K\n",
601                                        &key);
602                 }
603         }
604         // the caller is responsible for closing the transaction
605         // unless we return an error, they are also responsible for logging
606         // the inode.
607         //
608         pathrelse(&path);
609         /*
610          * cleanup prellocation from previous writes
611          * if this is a partial block write
612          */
613         if (write_bytes & (inode->i_sb->s_blocksize - 1))
614                 reiserfs_discard_prealloc(th, inode);
615         reiserfs_write_unlock(inode->i_sb);
616
617         // go through all the pages/buffers and map the buffers to newly allocated
618         // blocks (so that system knows where to write these pages later).
619         curr_block = 0;
620         for (i = 0; i < num_pages; i++) {
621                 struct page *page = prepared_pages[i];  //current page
622                 struct buffer_head *head = page_buffers(page);  // first buffer for a page
623                 int block_start, block_end;     // in-page offsets for buffers.
624
625                 if (!page_buffers(page))
626                         reiserfs_panic(inode->i_sb,
627                                        "green-9005: No buffers for prepared page???");
628
629                 /* For each buffer in page */
630                 for (bh = head, block_start = 0; bh != head || !block_start;
631                      block_start = block_end, bh = bh->b_this_page) {
632                         if (!bh)
633                                 reiserfs_panic(inode->i_sb,
634                                                "green-9006: Allocated but absent buffer for a page?");
635                         block_end = block_start + inode->i_sb->s_blocksize;
636                         if (i == 0 && block_end <= from)
637                                 /* if this buffer is before requested data to map, skip it */
638                                 continue;
639                         if (i == num_pages - 1 && block_start >= to)
640                                 /* If this buffer is after requested data to map, abort
641                                    processing of current page */
642                                 break;
643
644                         if (!buffer_mapped(bh)) {       // Ok, unmapped buffer, need to map it
645                                 map_bh(bh, inode->i_sb,
646                                        le32_to_cpu(allocated_blocks
647                                                    [curr_block]));
648                                 curr_block++;
649                                 set_buffer_new(bh);
650                         }
651                 }
652         }
653
654         RFALSE(curr_block > blocks_to_allocate,
655                "green-9007: Used too many blocks? weird");
656
657         kfree(allocated_blocks);
658         return 0;
659
660 // Need to deal with transaction here.
661       error_exit_free_blocks:
662         pathrelse(&path);
663         // free blocks
664         for (i = 0; i < blocks_to_allocate; i++)
665                 reiserfs_free_block(th, inode, le32_to_cpu(allocated_blocks[i]),
666                                     1);
667
668       error_exit:
669         if (th->t_trans_id) {
670                 int err;
671                 // update any changes we made to blk count
672                 mark_inode_dirty(inode);
673                 err =
674                     journal_end(th, inode->i_sb,
675                                 JOURNAL_PER_BALANCE_CNT * 3 + 1 +
676                                 2 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb));
677                 if (err)
678                         res = err;
679         }
680         reiserfs_write_unlock(inode->i_sb);
681         kfree(allocated_blocks);
682
683         return res;
684 }
685
686 /* Unlock pages prepared by reiserfs_prepare_file_region_for_write */
687 static void reiserfs_unprepare_pages(struct page **prepared_pages,      /* list of locked pages */
688                                      size_t num_pages /* amount of pages */ )
689 {
690         int i;                  // loop counter
691
692         for (i = 0; i < num_pages; i++) {
693                 struct page *page = prepared_pages[i];
694
695                 try_to_free_buffers(page);
696                 unlock_page(page);
697                 page_cache_release(page);
698         }
699 }
700
701 /* This function will copy data from userspace to specified pages within
702    supplied byte range */
703 static int reiserfs_copy_from_user_to_file_region(loff_t pos,   /* In-file position */
704                                                   int num_pages,        /* Number of pages affected */
705                                                   int write_bytes,      /* Amount of bytes to write */
706                                                   struct page **prepared_pages, /* pointer to 
707                                                                                    array to
708                                                                                    prepared pages
709                                                                                  */
710                                                   const char __user * buf       /* Pointer to user-supplied
711                                                                                    data */
712     )
713 {
714         long page_fault = 0;    // status of copy_from_user.
715         int i;                  // loop counter.
716         int offset;             // offset in page
717
718         for (i = 0, offset = (pos & (PAGE_CACHE_SIZE - 1)); i < num_pages;
719              i++, offset = 0) {
720                 size_t count = min_t(size_t, PAGE_CACHE_SIZE - offset, write_bytes);    // How much of bytes to write to this page
721                 struct page *page = prepared_pages[i];  // Current page we process.
722
723                 fault_in_pages_readable(buf, count);
724
725                 /* Copy data from userspace to the current page */
726                 kmap(page);
727                 page_fault = __copy_from_user(page_address(page) + offset, buf, count); // Copy the data.
728                 /* Flush processor's dcache for this page */
729                 flush_dcache_page(page);
730                 kunmap(page);
731                 buf += count;
732                 write_bytes -= count;
733
734                 if (page_fault)
735                         break;  // Was there a fault? abort.
736         }
737
738         return page_fault ? -EFAULT : 0;
739 }
740
741 /* taken fs/buffer.c:__block_commit_write */
742 int reiserfs_commit_page(struct inode *inode, struct page *page,
743                          unsigned from, unsigned to)
744 {
745         unsigned block_start, block_end;
746         int partial = 0;
747         unsigned blocksize;
748         struct buffer_head *bh, *head;
749         unsigned long i_size_index = inode->i_size >> PAGE_CACHE_SHIFT;
750         int new;
751         int logit = reiserfs_file_data_log(inode);
752         struct super_block *s = inode->i_sb;
753         int bh_per_page = PAGE_CACHE_SIZE / s->s_blocksize;
754         struct reiserfs_transaction_handle th;
755         int ret = 0;
756
757         th.t_trans_id = 0;
758         blocksize = 1 << inode->i_blkbits;
759
760         if (logit) {
761                 reiserfs_write_lock(s);
762                 ret = journal_begin(&th, s, bh_per_page + 1);
763                 if (ret)
764                         goto drop_write_lock;
765                 reiserfs_update_inode_transaction(inode);
766         }
767         for (bh = head = page_buffers(page), block_start = 0;
768              bh != head || !block_start;
769              block_start = block_end, bh = bh->b_this_page) {
770
771                 new = buffer_new(bh);
772                 clear_buffer_new(bh);
773                 block_end = block_start + blocksize;
774                 if (block_end <= from || block_start >= to) {
775                         if (!buffer_uptodate(bh))
776                                 partial = 1;
777                 } else {
778                         set_buffer_uptodate(bh);
779                         if (logit) {
780                                 reiserfs_prepare_for_journal(s, bh, 1);
781                                 journal_mark_dirty(&th, s, bh);
782                         } else if (!buffer_dirty(bh)) {
783                                 mark_buffer_dirty(bh);
784                                 /* do data=ordered on any page past the end
785                                  * of file and any buffer marked BH_New.
786                                  */
787                                 if (reiserfs_data_ordered(inode->i_sb) &&
788                                     (new || page->index >= i_size_index)) {
789                                         reiserfs_add_ordered_list(inode, bh);
790                                 }
791                         }
792                 }
793         }
794         if (logit) {
795                 ret = journal_end(&th, s, bh_per_page + 1);
796               drop_write_lock:
797                 reiserfs_write_unlock(s);
798         }
799         /*
800          * If this is a partial write which happened to make all buffers
801          * uptodate then we can optimize away a bogus readpage() for
802          * the next read(). Here we 'discover' whether the page went
803          * uptodate as a result of this (potentially partial) write.
804          */
805         if (!partial)
806                 SetPageUptodate(page);
807         return ret;
808 }
809
810 /* Submit pages for write. This was separated from actual file copying
811    because we might want to allocate block numbers in-between.
812    This function assumes that caller will adjust file size to correct value. */
813 static int reiserfs_submit_file_region_for_write(struct reiserfs_transaction_handle *th, struct inode *inode, loff_t pos,       /* Writing position offset */
814                                                  size_t num_pages,      /* Number of pages to write */
815                                                  size_t write_bytes,    /* number of bytes to write */
816                                                  struct page **prepared_pages   /* list of pages */
817     )
818 {
819         int status;             // return status of block_commit_write.
820         int retval = 0;         // Return value we are going to return.
821         int i;                  // loop counter
822         int offset;             // Writing offset in page.
823         int orig_write_bytes = write_bytes;
824         int sd_update = 0;
825
826         for (i = 0, offset = (pos & (PAGE_CACHE_SIZE - 1)); i < num_pages;
827              i++, offset = 0) {
828                 int count = min_t(int, PAGE_CACHE_SIZE - offset, write_bytes);  // How much of bytes to write to this page
829                 struct page *page = prepared_pages[i];  // Current page we process.
830
831                 status =
832                     reiserfs_commit_page(inode, page, offset, offset + count);
833                 if (status)
834                         retval = status;        // To not overcomplicate matters We are going to
835                 // submit all the pages even if there was error.
836                 // we only remember error status to report it on
837                 // exit.
838                 write_bytes -= count;
839         }
840         /* now that we've gotten all the ordered buffers marked dirty,
841          * we can safely update i_size and close any running transaction
842          */
843         if (pos + orig_write_bytes > inode->i_size) {
844                 inode->i_size = pos + orig_write_bytes; // Set new size
845                 /* If the file have grown so much that tail packing is no
846                  * longer possible, reset "need to pack" flag */
847                 if ((have_large_tails(inode->i_sb) &&
848                      inode->i_size > i_block_size(inode) * 4) ||
849                     (have_small_tails(inode->i_sb) &&
850                      inode->i_size > i_block_size(inode)))
851                         REISERFS_I(inode)->i_flags &= ~i_pack_on_close_mask;
852                 else if ((have_large_tails(inode->i_sb) &&
853                           inode->i_size < i_block_size(inode) * 4) ||
854                          (have_small_tails(inode->i_sb) &&
855                           inode->i_size < i_block_size(inode)))
856                         REISERFS_I(inode)->i_flags |= i_pack_on_close_mask;
857
858                 if (th->t_trans_id) {
859                         reiserfs_write_lock(inode->i_sb);
860                         // this sets the proper flags for O_SYNC to trigger a commit
861                         mark_inode_dirty(inode);
862                         reiserfs_write_unlock(inode->i_sb);
863                 } else {
864                         reiserfs_write_lock(inode->i_sb);
865                         reiserfs_update_inode_transaction(inode);
866                         mark_inode_dirty(inode);
867                         reiserfs_write_unlock(inode->i_sb);
868                 }
869
870                 sd_update = 1;
871         }
872         if (th->t_trans_id) {
873                 reiserfs_write_lock(inode->i_sb);
874                 if (!sd_update)
875                         mark_inode_dirty(inode);
876                 status = journal_end(th, th->t_super, th->t_blocks_allocated);
877                 if (status)
878                         retval = status;
879                 reiserfs_write_unlock(inode->i_sb);
880         }
881         th->t_trans_id = 0;
882
883         /* 
884          * we have to unlock the pages after updating i_size, otherwise
885          * we race with writepage
886          */
887         for (i = 0; i < num_pages; i++) {
888                 struct page *page = prepared_pages[i];
889                 unlock_page(page);
890                 mark_page_accessed(page);
891                 page_cache_release(page);
892         }
893         return retval;
894 }
895
896 /* Look if passed writing region is going to touch file's tail
897    (if it is present). And if it is, convert the tail to unformatted node */
898 static int reiserfs_check_for_tail_and_convert(struct inode *inode,     /* inode to deal with */
899                                                loff_t pos,      /* Writing position */
900                                                int write_bytes  /* amount of bytes to write */
901     )
902 {
903         INITIALIZE_PATH(path);  // needed for search_for_position
904         struct cpu_key key;     // Key that would represent last touched writing byte.
905         struct item_head *ih;   // item header of found block;
906         int res;                // Return value of various functions we call.
907         int cont_expand_offset; // We will put offset for generic_cont_expand here
908         // This can be int just because tails are created
909         // only for small files.
910
911 /* this embodies a dependency on a particular tail policy */
912         if (inode->i_size >= inode->i_sb->s_blocksize * 4) {
913                 /* such a big files do not have tails, so we won't bother ourselves
914                    to look for tails, simply return */
915                 return 0;
916         }
917
918         reiserfs_write_lock(inode->i_sb);
919         /* find the item containing the last byte to be written, or if
920          * writing past the end of the file then the last item of the
921          * file (and then we check its type). */
922         make_cpu_key(&key, inode, pos + write_bytes + 1, TYPE_ANY,
923                      3 /*key length */ );
924         res = search_for_position_by_key(inode->i_sb, &key, &path);
925         if (res == IO_ERROR) {
926                 reiserfs_write_unlock(inode->i_sb);
927                 return -EIO;
928         }
929         ih = get_ih(&path);
930         res = 0;
931         if (is_direct_le_ih(ih)) {
932                 /* Ok, closest item is file tail (tails are stored in "direct"
933                  * items), so we need to unpack it. */
934                 /* To not overcomplicate matters, we just call generic_cont_expand
935                    which will in turn call other stuff and finally will boil down to
936                    reiserfs_get_block() that would do necessary conversion. */
937                 cont_expand_offset =
938                     le_key_k_offset(get_inode_item_key_version(inode),
939                                     &(ih->ih_key));
940                 pathrelse(&path);
941                 res = generic_cont_expand(inode, cont_expand_offset);
942         } else
943                 pathrelse(&path);
944
945         reiserfs_write_unlock(inode->i_sb);
946         return res;
947 }
948
949 /* This function locks pages starting from @pos for @inode.
950    @num_pages pages are locked and stored in
951    @prepared_pages array. Also buffers are allocated for these pages.
952    First and last page of the region is read if it is overwritten only
953    partially. If last page did not exist before write (file hole or file
954    append), it is zeroed, then. 
955    Returns number of unallocated blocks that should be allocated to cover
956    new file data.*/
957 static int reiserfs_prepare_file_region_for_write(struct inode *inode
958                                                   /* Inode of the file */ ,
959                                                   loff_t pos,   /* position in the file */
960                                                   size_t num_pages,     /* number of pages to
961                                                                            prepare */
962                                                   size_t write_bytes,   /* Amount of bytes to be
963                                                                            overwritten from
964                                                                            @pos */
965                                                   struct page **prepared_pages  /* pointer to array
966                                                                                    where to store
967                                                                                    prepared pages */
968     )
969 {
970         int res = 0;            // Return values of different functions we call.
971         unsigned long index = pos >> PAGE_CACHE_SHIFT;  // Offset in file in pages.
972         int from = (pos & (PAGE_CACHE_SIZE - 1));       // Writing offset in first page
973         int to = ((pos + write_bytes - 1) & (PAGE_CACHE_SIZE - 1)) + 1;
974         /* offset of last modified byte in last
975            page */
976         struct address_space *mapping = inode->i_mapping;       // Pages are mapped here.
977         int i;                  // Simple counter
978         int blocks = 0;         /* Return value (blocks that should be allocated) */
979         struct buffer_head *bh, *head;  // Current bufferhead and first bufferhead
980         // of a page.
981         unsigned block_start, block_end;        // Starting and ending offsets of current
982         // buffer in the page.
983         struct buffer_head *wait[2], **wait_bh = wait;  // Buffers for page, if
984         // Page appeared to be not up
985         // to date. Note how we have
986         // at most 2 buffers, this is
987         // because we at most may
988         // partially overwrite two
989         // buffers for one page. One at                                                 // the beginning of write area
990         // and one at the end.
991         // Everything inthe middle gets                                                 // overwritten totally.
992
993         struct cpu_key key;     // cpu key of item that we are going to deal with
994         struct item_head *ih = NULL;    // pointer to item head that we are going to deal with
995         struct buffer_head *itembuf = NULL;     // Buffer head that contains items that we are going to deal with
996         INITIALIZE_PATH(path);  // path to item, that we are going to deal with.
997         __le32 *item = NULL;    // pointer to item we are going to deal with
998         int item_pos = -1;      /* Position in indirect item */
999
1000         if (num_pages < 1) {
1001                 reiserfs_warning(inode->i_sb,
1002                                  "green-9001: reiserfs_prepare_file_region_for_write "
1003                                  "called with zero number of pages to process");
1004                 return -EFAULT;
1005         }
1006
1007         /* We have 2 loops for pages. In first loop we grab and lock the pages, so
1008            that nobody would touch these until we release the pages. Then
1009            we'd start to deal with mapping buffers to blocks. */
1010         for (i = 0; i < num_pages; i++) {
1011                 prepared_pages[i] = grab_cache_page(mapping, index + i);        // locks the page
1012                 if (!prepared_pages[i]) {
1013                         res = -ENOMEM;
1014                         goto failed_page_grabbing;
1015                 }
1016                 if (!page_has_buffers(prepared_pages[i]))
1017                         create_empty_buffers(prepared_pages[i],
1018                                              inode->i_sb->s_blocksize, 0);
1019         }
1020
1021         /* Let's count amount of blocks for a case where all the blocks
1022            overwritten are new (we will substract already allocated blocks later) */
1023         if (num_pages > 2)
1024                 /* These are full-overwritten pages so we count all the blocks in
1025                    these pages are counted as needed to be allocated */
1026                 blocks =
1027                     (num_pages - 2) << (PAGE_CACHE_SHIFT - inode->i_blkbits);
1028
1029         /* count blocks needed for first page (possibly partially written) */
1030         blocks += ((PAGE_CACHE_SIZE - from) >> inode->i_blkbits) + !!(from & (inode->i_sb->s_blocksize - 1));   /* roundup */
1031
1032         /* Now we account for last page. If last page == first page (we
1033            overwrite only one page), we substract all the blocks past the
1034            last writing position in a page out of already calculated number
1035            of blocks */
1036         blocks += ((num_pages > 1) << (PAGE_CACHE_SHIFT - inode->i_blkbits)) -
1037             ((PAGE_CACHE_SIZE - to) >> inode->i_blkbits);
1038         /* Note how we do not roundup here since partial blocks still
1039            should be allocated */
1040
1041         /* Now if all the write area lies past the file end, no point in
1042            maping blocks, since there is none, so we just zero out remaining
1043            parts of first and last pages in write area (if needed) */
1044         if ((pos & ~((loff_t) PAGE_CACHE_SIZE - 1)) > inode->i_size) {
1045                 if (from != 0) {        /* First page needs to be partially zeroed */
1046                         char *kaddr = kmap_atomic(prepared_pages[0], KM_USER0);
1047                         memset(kaddr, 0, from);
1048                         kunmap_atomic(kaddr, KM_USER0);
1049                 }
1050                 if (to != PAGE_CACHE_SIZE) {    /* Last page needs to be partially zeroed */
1051                         char *kaddr =
1052                             kmap_atomic(prepared_pages[num_pages - 1],
1053                                         KM_USER0);
1054                         memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
1055                         kunmap_atomic(kaddr, KM_USER0);
1056                 }
1057
1058                 /* Since all blocks are new - use already calculated value */
1059                 return blocks;
1060         }
1061
1062         /* Well, since we write somewhere into the middle of a file, there is
1063            possibility we are writing over some already allocated blocks, so
1064            let's map these blocks and substract number of such blocks out of blocks
1065            we need to allocate (calculated above) */
1066         /* Mask write position to start on blocksize, we do it out of the
1067            loop for performance reasons */
1068         pos &= ~((loff_t) inode->i_sb->s_blocksize - 1);
1069         /* Set cpu key to the starting position in a file (on left block boundary) */
1070         make_cpu_key(&key, inode,
1071                      1 + ((pos) & ~((loff_t) inode->i_sb->s_blocksize - 1)),
1072                      TYPE_ANY, 3 /*key length */ );
1073
1074         reiserfs_write_lock(inode->i_sb);       // We need that for at least search_by_key()
1075         for (i = 0; i < num_pages; i++) {
1076
1077                 head = page_buffers(prepared_pages[i]);
1078                 /* For each buffer in the page */
1079                 for (bh = head, block_start = 0; bh != head || !block_start;
1080                      block_start = block_end, bh = bh->b_this_page) {
1081                         if (!bh)
1082                                 reiserfs_panic(inode->i_sb,
1083                                                "green-9002: Allocated but absent buffer for a page?");
1084                         /* Find where this buffer ends */
1085                         block_end = block_start + inode->i_sb->s_blocksize;
1086                         if (i == 0 && block_end <= from)
1087                                 /* if this buffer is before requested data to map, skip it */
1088                                 continue;
1089
1090                         if (i == num_pages - 1 && block_start >= to) {
1091                                 /* If this buffer is after requested data to map, abort
1092                                    processing of current page */
1093                                 break;
1094                         }
1095
1096                         if (buffer_mapped(bh) && bh->b_blocknr != 0) {
1097                                 /* This is optimisation for a case where buffer is mapped
1098                                    and have blocknumber assigned. In case significant amount
1099                                    of such buffers are present, we may avoid some amount
1100                                    of search_by_key calls.
1101                                    Probably it would be possible to move parts of this code
1102                                    out of BKL, but I afraid that would overcomplicate code
1103                                    without any noticeable benefit.
1104                                  */
1105                                 item_pos++;
1106                                 /* Update the key */
1107                                 set_cpu_key_k_offset(&key,
1108                                                      cpu_key_k_offset(&key) +
1109                                                      inode->i_sb->s_blocksize);
1110                                 blocks--;       // Decrease the amount of blocks that need to be
1111                                 // allocated
1112                                 continue;       // Go to the next buffer
1113                         }
1114
1115                         if (!itembuf || /* if first iteration */
1116                             item_pos >= ih_item_len(ih) / UNFM_P_SIZE) {        /* or if we progressed past the
1117                                                                                    current unformatted_item */
1118                                 /* Try to find next item */
1119                                 res =
1120                                     search_for_position_by_key(inode->i_sb,
1121                                                                &key, &path);
1122                                 /* Abort if no more items */
1123                                 if (res != POSITION_FOUND) {
1124                                         /* make sure later loops don't use this item */
1125                                         itembuf = NULL;
1126                                         item = NULL;
1127                                         break;
1128                                 }
1129
1130                                 /* Update information about current indirect item */
1131                                 itembuf = get_last_bh(&path);
1132                                 ih = get_ih(&path);
1133                                 item = get_item(&path);
1134                                 item_pos = path.pos_in_item;
1135
1136                                 RFALSE(!is_indirect_le_ih(ih),
1137                                        "green-9003: indirect item expected");
1138                         }
1139
1140                         /* See if there is some block associated with the file
1141                            at that position, map the buffer to this block */
1142                         if (get_block_num(item, item_pos)) {
1143                                 map_bh(bh, inode->i_sb,
1144                                        get_block_num(item, item_pos));
1145                                 blocks--;       // Decrease the amount of blocks that need to be
1146                                 // allocated
1147                         }
1148                         item_pos++;
1149                         /* Update the key */
1150                         set_cpu_key_k_offset(&key,
1151                                              cpu_key_k_offset(&key) +
1152                                              inode->i_sb->s_blocksize);
1153                 }
1154         }
1155         pathrelse(&path);       // Free the path
1156         reiserfs_write_unlock(inode->i_sb);
1157
1158         /* Now zero out unmappend buffers for the first and last pages of
1159            write area or issue read requests if page is mapped. */
1160         /* First page, see if it is not uptodate */
1161         if (!PageUptodate(prepared_pages[0])) {
1162                 head = page_buffers(prepared_pages[0]);
1163
1164                 /* For each buffer in page */
1165                 for (bh = head, block_start = 0; bh != head || !block_start;
1166                      block_start = block_end, bh = bh->b_this_page) {
1167
1168                         if (!bh)
1169                                 reiserfs_panic(inode->i_sb,
1170                                                "green-9002: Allocated but absent buffer for a page?");
1171                         /* Find where this buffer ends */
1172                         block_end = block_start + inode->i_sb->s_blocksize;
1173                         if (block_end <= from)
1174                                 /* if this buffer is before requested data to map, skip it */
1175                                 continue;
1176                         if (block_start < from) {       /* Aha, our partial buffer */
1177                                 if (buffer_mapped(bh)) {        /* If it is mapped, we need to
1178                                                                    issue READ request for it to
1179                                                                    not loose data */
1180                                         ll_rw_block(READ, 1, &bh);
1181                                         *wait_bh++ = bh;
1182                                 } else {        /* Not mapped, zero it */
1183                                         char *kaddr =
1184                                             kmap_atomic(prepared_pages[0],
1185                                                         KM_USER0);
1186                                         memset(kaddr + block_start, 0,
1187                                                from - block_start);
1188                                         kunmap_atomic(kaddr, KM_USER0);
1189                                         set_buffer_uptodate(bh);
1190                                 }
1191                         }
1192                 }
1193         }
1194
1195         /* Last page, see if it is not uptodate, or if the last page is past the end of the file. */
1196         if (!PageUptodate(prepared_pages[num_pages - 1]) ||
1197             ((pos + write_bytes) >> PAGE_CACHE_SHIFT) >
1198             (inode->i_size >> PAGE_CACHE_SHIFT)) {
1199                 head = page_buffers(prepared_pages[num_pages - 1]);
1200
1201                 /* for each buffer in page */
1202                 for (bh = head, block_start = 0; bh != head || !block_start;
1203                      block_start = block_end, bh = bh->b_this_page) {
1204
1205                         if (!bh)
1206                                 reiserfs_panic(inode->i_sb,
1207                                                "green-9002: Allocated but absent buffer for a page?");
1208                         /* Find where this buffer ends */
1209                         block_end = block_start + inode->i_sb->s_blocksize;
1210                         if (block_start >= to)
1211                                 /* if this buffer is after requested data to map, skip it */
1212                                 break;
1213                         if (block_end > to) {   /* Aha, our partial buffer */
1214                                 if (buffer_mapped(bh)) {        /* If it is mapped, we need to
1215                                                                    issue READ request for it to
1216                                                                    not loose data */
1217                                         ll_rw_block(READ, 1, &bh);
1218                                         *wait_bh++ = bh;
1219                                 } else {        /* Not mapped, zero it */
1220                                         char *kaddr =
1221                                             kmap_atomic(prepared_pages
1222                                                         [num_pages - 1],
1223                                                         KM_USER0);
1224                                         memset(kaddr + to, 0, block_end - to);
1225                                         kunmap_atomic(kaddr, KM_USER0);
1226                                         set_buffer_uptodate(bh);
1227                                 }
1228                         }
1229                 }
1230         }
1231
1232         /* Wait for read requests we made to happen, if necessary */
1233         while (wait_bh > wait) {
1234                 wait_on_buffer(*--wait_bh);
1235                 if (!buffer_uptodate(*wait_bh)) {
1236                         res = -EIO;
1237                         goto failed_read;
1238                 }
1239         }
1240
1241         return blocks;
1242       failed_page_grabbing:
1243         num_pages = i;
1244       failed_read:
1245         reiserfs_unprepare_pages(prepared_pages, num_pages);
1246         return res;
1247 }
1248
1249 /* Write @count bytes at position @ppos in a file indicated by @file
1250    from the buffer @buf.  
1251
1252    generic_file_write() is only appropriate for filesystems that are not seeking to optimize performance and want
1253    something simple that works.  It is not for serious use by general purpose filesystems, excepting the one that it was
1254    written for (ext2/3).  This is for several reasons:
1255
1256    * It has no understanding of any filesystem specific optimizations.
1257
1258    * It enters the filesystem repeatedly for each page that is written.
1259
1260    * It depends on reiserfs_get_block() function which if implemented by reiserfs performs costly search_by_key
1261    * operation for each page it is supplied with. By contrast reiserfs_file_write() feeds as much as possible at a time
1262    * to reiserfs which allows for fewer tree traversals.
1263
1264    * Each indirect pointer insertion takes a lot of cpu, because it involves memory moves inside of blocks.
1265
1266    * Asking the block allocation code for blocks one at a time is slightly less efficient.
1267
1268    All of these reasons for not using only generic file write were understood back when reiserfs was first miscoded to
1269    use it, but we were in a hurry to make code freeze, and so it couldn't be revised then.  This new code should make
1270    things right finally.
1271
1272    Future Features: providing search_by_key with hints.
1273
1274 */
1275 static ssize_t reiserfs_file_write(struct file *file,   /* the file we are going to write into */
1276                                    const char __user * buf,     /*  pointer to user supplied data
1277                                                                    (in userspace) */
1278                                    size_t count,        /* amount of bytes to write */
1279                                    loff_t * ppos        /* pointer to position in file that we start writing at. Should be updated to
1280                                                          * new current position before returning. */
1281                                    )
1282 {
1283         size_t already_written = 0;     // Number of bytes already written to the file.
1284         loff_t pos;             // Current position in the file.
1285         ssize_t res;            // return value of various functions that we call.
1286         int err = 0;
1287         struct inode *inode = file->f_dentry->d_inode;  // Inode of the file that we are writing to.
1288         /* To simplify coding at this time, we store
1289            locked pages in array for now */
1290         struct page *prepared_pages[REISERFS_WRITE_PAGES_AT_A_TIME];
1291         struct reiserfs_transaction_handle th;
1292         th.t_trans_id = 0;
1293
1294         /* If a filesystem is converted from 3.5 to 3.6, we'll have v3.5 items
1295         * lying around (most of the disk, in fact). Despite the filesystem
1296         * now being a v3.6 format, the old items still can't support large
1297         * file sizes. Catch this case here, as the rest of the VFS layer is
1298         * oblivious to the different limitations between old and new items.
1299         * reiserfs_setattr catches this for truncates. This chunk is lifted
1300         * from generic_write_checks. */
1301         if (get_inode_item_key_version (inode) == KEY_FORMAT_3_5 &&
1302             *ppos + count > MAX_NON_LFS) {
1303                 if (*ppos >= MAX_NON_LFS) {
1304                         send_sig(SIGXFSZ, current, 0);
1305                         return -EFBIG;
1306                 }
1307                 if (count > MAX_NON_LFS - (unsigned long)*ppos)
1308                         count = MAX_NON_LFS - (unsigned long)*ppos;
1309         }
1310
1311         if (file->f_flags & O_DIRECT) { // Direct IO needs treatment
1312                 ssize_t result, after_file_end = 0;
1313                 if ((*ppos + count >= inode->i_size)
1314                     || (file->f_flags & O_APPEND)) {
1315                         /* If we are appending a file, we need to put this savelink in here.
1316                            If we will crash while doing direct io, finish_unfinished will
1317                            cut the garbage from the file end. */
1318                         reiserfs_write_lock(inode->i_sb);
1319                         err =
1320                             journal_begin(&th, inode->i_sb,
1321                                           JOURNAL_PER_BALANCE_CNT);
1322                         if (err) {
1323                                 reiserfs_write_unlock(inode->i_sb);
1324                                 return err;
1325                         }
1326                         reiserfs_update_inode_transaction(inode);
1327                         add_save_link(&th, inode, 1 /* Truncate */ );
1328                         after_file_end = 1;
1329                         err =
1330                             journal_end(&th, inode->i_sb,
1331                                         JOURNAL_PER_BALANCE_CNT);
1332                         reiserfs_write_unlock(inode->i_sb);
1333                         if (err)
1334                                 return err;
1335                 }
1336                 result = generic_file_write(file, buf, count, ppos);
1337
1338                 if (after_file_end) {   /* Now update i_size and remove the savelink */
1339                         struct reiserfs_transaction_handle th;
1340                         reiserfs_write_lock(inode->i_sb);
1341                         err = journal_begin(&th, inode->i_sb, 1);
1342                         if (err) {
1343                                 reiserfs_write_unlock(inode->i_sb);
1344                                 return err;
1345                         }
1346                         reiserfs_update_inode_transaction(inode);
1347                         mark_inode_dirty(inode);
1348                         err = journal_end(&th, inode->i_sb, 1);
1349                         if (err) {
1350                                 reiserfs_write_unlock(inode->i_sb);
1351                                 return err;
1352                         }
1353                         err = remove_save_link(inode, 1 /* truncate */ );
1354                         reiserfs_write_unlock(inode->i_sb);
1355                         if (err)
1356                                 return err;
1357                 }
1358
1359                 return result;
1360         }
1361
1362         if (unlikely((ssize_t) count < 0))
1363                 return -EINVAL;
1364
1365         if (unlikely(!access_ok(VERIFY_READ, buf, count)))
1366                 return -EFAULT;
1367
1368         mutex_lock(&inode->i_mutex);    // locks the entire file for just us
1369
1370         pos = *ppos;
1371
1372         /* Check if we can write to specified region of file, file
1373            is not overly big and this kind of stuff. Adjust pos and
1374            count, if needed */
1375         res = generic_write_checks(file, &pos, &count, 0);
1376         if (res)
1377                 goto out;
1378
1379         if (count == 0)
1380                 goto out;
1381
1382         res = remove_suid(file->f_dentry);
1383         if (res)
1384                 goto out;
1385
1386         file_update_time(file);
1387
1388         // Ok, we are done with all the checks.
1389
1390         // Now we should start real work
1391
1392         /* If we are going to write past the file's packed tail or if we are going
1393            to overwrite part of the tail, we need that tail to be converted into
1394            unformatted node */
1395         res = reiserfs_check_for_tail_and_convert(inode, pos, count);
1396         if (res)
1397                 goto out;
1398
1399         while (count > 0) {
1400                 /* This is the main loop in which we running until some error occures
1401                    or until we write all of the data. */
1402                 size_t num_pages;       /* amount of pages we are going to write this iteration */
1403                 size_t write_bytes;     /* amount of bytes to write during this iteration */
1404                 size_t blocks_to_allocate;      /* how much blocks we need to allocate for this iteration */
1405
1406                 /*  (pos & (PAGE_CACHE_SIZE-1)) is an idiom for offset into a page of pos */
1407                 num_pages = !!((pos + count) & (PAGE_CACHE_SIZE - 1)) + /* round up partial
1408                                                                            pages */
1409                     ((count +
1410                       (pos & (PAGE_CACHE_SIZE - 1))) >> PAGE_CACHE_SHIFT);
1411                 /* convert size to amount of
1412                    pages */
1413                 reiserfs_write_lock(inode->i_sb);
1414                 if (num_pages > REISERFS_WRITE_PAGES_AT_A_TIME
1415                     || num_pages > reiserfs_can_fit_pages(inode->i_sb)) {
1416                         /* If we were asked to write more data than we want to or if there
1417                            is not that much space, then we shorten amount of data to write
1418                            for this iteration. */
1419                         num_pages =
1420                             min_t(size_t, REISERFS_WRITE_PAGES_AT_A_TIME,
1421                                   reiserfs_can_fit_pages(inode->i_sb));
1422                         /* Also we should not forget to set size in bytes accordingly */
1423                         write_bytes = (num_pages << PAGE_CACHE_SHIFT) -
1424                             (pos & (PAGE_CACHE_SIZE - 1));
1425                         /* If position is not on the
1426                            start of the page, we need
1427                            to substract the offset
1428                            within page */
1429                 } else
1430                         write_bytes = count;
1431
1432                 /* reserve the blocks to be allocated later, so that later on
1433                    we still have the space to write the blocks to */
1434                 reiserfs_claim_blocks_to_be_allocated(inode->i_sb,
1435                                                       num_pages <<
1436                                                       (PAGE_CACHE_SHIFT -
1437                                                        inode->i_blkbits));
1438                 reiserfs_write_unlock(inode->i_sb);
1439
1440                 if (!num_pages) {       /* If we do not have enough space even for a single page... */
1441                         if (pos >
1442                             inode->i_size + inode->i_sb->s_blocksize -
1443                             (pos & (inode->i_sb->s_blocksize - 1))) {
1444                                 res = -ENOSPC;
1445                                 break;  // In case we are writing past the end of the last file block, break.
1446                         }
1447                         // Otherwise we are possibly overwriting the file, so
1448                         // let's set write size to be equal or less than blocksize.
1449                         // This way we get it correctly for file holes.
1450                         // But overwriting files on absolutelly full volumes would not
1451                         // be very efficient. Well, people are not supposed to fill
1452                         // 100% of disk space anyway.
1453                         write_bytes =
1454                             min_t(size_t, count,
1455                                   inode->i_sb->s_blocksize -
1456                                   (pos & (inode->i_sb->s_blocksize - 1)));
1457                         num_pages = 1;
1458                         // No blocks were claimed before, so do it now.
1459                         reiserfs_claim_blocks_to_be_allocated(inode->i_sb,
1460                                                               1 <<
1461                                                               (PAGE_CACHE_SHIFT
1462                                                                -
1463                                                                inode->
1464                                                                i_blkbits));
1465                 }
1466
1467                 /* Prepare for writing into the region, read in all the
1468                    partially overwritten pages, if needed. And lock the pages,
1469                    so that nobody else can access these until we are done.
1470                    We get number of actual blocks needed as a result. */
1471                 res = reiserfs_prepare_file_region_for_write(inode, pos,
1472                                                              num_pages,
1473                                                              write_bytes,
1474                                                              prepared_pages);
1475                 if (res < 0) {
1476                         reiserfs_release_claimed_blocks(inode->i_sb,
1477                                                         num_pages <<
1478                                                         (PAGE_CACHE_SHIFT -
1479                                                          inode->i_blkbits));
1480                         break;
1481                 }
1482
1483                 blocks_to_allocate = res;
1484
1485                 /* First we correct our estimate of how many blocks we need */
1486                 reiserfs_release_claimed_blocks(inode->i_sb,
1487                                                 (num_pages <<
1488                                                  (PAGE_CACHE_SHIFT -
1489                                                   inode->i_sb->
1490                                                   s_blocksize_bits)) -
1491                                                 blocks_to_allocate);
1492
1493                 if (blocks_to_allocate > 0) {   /*We only allocate blocks if we need to */
1494                         /* Fill in all the possible holes and append the file if needed */
1495                         res =
1496                             reiserfs_allocate_blocks_for_region(&th, inode, pos,
1497                                                                 num_pages,
1498                                                                 write_bytes,
1499                                                                 prepared_pages,
1500                                                                 blocks_to_allocate);
1501                 }
1502
1503                 /* well, we have allocated the blocks, so it is time to free
1504                    the reservation we made earlier. */
1505                 reiserfs_release_claimed_blocks(inode->i_sb,
1506                                                 blocks_to_allocate);
1507                 if (res) {
1508                         reiserfs_unprepare_pages(prepared_pages, num_pages);
1509                         break;
1510                 }
1511
1512 /* NOTE that allocating blocks and filling blocks can be done in reverse order
1513    and probably we would do that just to get rid of garbage in files after a
1514    crash */
1515
1516                 /* Copy data from user-supplied buffer to file's pages */
1517                 res =
1518                     reiserfs_copy_from_user_to_file_region(pos, num_pages,
1519                                                            write_bytes,
1520                                                            prepared_pages, buf);
1521                 if (res) {
1522                         reiserfs_unprepare_pages(prepared_pages, num_pages);
1523                         break;
1524                 }
1525
1526                 /* Send the pages to disk and unlock them. */
1527                 res =
1528                     reiserfs_submit_file_region_for_write(&th, inode, pos,
1529                                                           num_pages,
1530                                                           write_bytes,
1531                                                           prepared_pages);
1532                 if (res)
1533                         break;
1534
1535                 already_written += write_bytes;
1536                 buf += write_bytes;
1537                 *ppos = pos += write_bytes;
1538                 count -= write_bytes;
1539                 balance_dirty_pages_ratelimited_nr(inode->i_mapping, num_pages);
1540         }
1541
1542         /* this is only true on error */
1543         if (th.t_trans_id) {
1544                 reiserfs_write_lock(inode->i_sb);
1545                 err = journal_end(&th, th.t_super, th.t_blocks_allocated);
1546                 reiserfs_write_unlock(inode->i_sb);
1547                 if (err) {
1548                         res = err;
1549                         goto out;
1550                 }
1551         }
1552
1553         if (likely(res >= 0) &&
1554             (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))))
1555                 res = generic_osync_inode(inode, file->f_mapping,
1556                                           OSYNC_METADATA | OSYNC_DATA);
1557
1558         mutex_unlock(&inode->i_mutex);
1559         reiserfs_async_progress_wait(inode->i_sb);
1560         return (already_written != 0) ? already_written : res;
1561
1562       out:
1563         mutex_unlock(&inode->i_mutex);  // unlock the file on exit.
1564         return res;
1565 }
1566
1567 const struct file_operations reiserfs_file_operations = {
1568         .read = generic_file_read,
1569         .write = reiserfs_file_write,
1570         .ioctl = reiserfs_ioctl,
1571         .mmap = generic_file_mmap,
1572         .release = reiserfs_file_release,
1573         .fsync = reiserfs_sync_file,
1574         .sendfile = generic_file_sendfile,
1575         .aio_read = generic_file_aio_read,
1576         .aio_write = generic_file_aio_write,
1577         .splice_read = generic_file_splice_read,
1578         .splice_write = generic_file_splice_write,
1579 };
1580
1581 struct inode_operations reiserfs_file_inode_operations = {
1582         .truncate = reiserfs_vfs_truncate_file,
1583         .setattr = reiserfs_setattr,
1584         .setxattr = reiserfs_setxattr,
1585         .getxattr = reiserfs_getxattr,
1586         .listxattr = reiserfs_listxattr,
1587         .removexattr = reiserfs_removexattr,
1588         .permission = reiserfs_permission,
1589 };