Btrfs: Mixed back reference (FORWARD ROLLING FORMAT CHANGE)
[linux-3.10.git] / fs / btrfs / file.c
1 /*
2  * Copyright (C) 2007 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18
19 #include <linux/fs.h>
20 #include <linux/pagemap.h>
21 #include <linux/highmem.h>
22 #include <linux/time.h>
23 #include <linux/init.h>
24 #include <linux/string.h>
25 #include <linux/smp_lock.h>
26 #include <linux/backing-dev.h>
27 #include <linux/mpage.h>
28 #include <linux/swap.h>
29 #include <linux/writeback.h>
30 #include <linux/statfs.h>
31 #include <linux/compat.h>
32 #include "ctree.h"
33 #include "disk-io.h"
34 #include "transaction.h"
35 #include "btrfs_inode.h"
36 #include "ioctl.h"
37 #include "print-tree.h"
38 #include "tree-log.h"
39 #include "locking.h"
40 #include "compat.h"
41
42
43 /* simple helper to fault in pages and copy.  This should go away
44  * and be replaced with calls into generic code.
45  */
46 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
47                                          int write_bytes,
48                                          struct page **prepared_pages,
49                                          const char __user *buf)
50 {
51         long page_fault = 0;
52         int i;
53         int offset = pos & (PAGE_CACHE_SIZE - 1);
54
55         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
56                 size_t count = min_t(size_t,
57                                      PAGE_CACHE_SIZE - offset, write_bytes);
58                 struct page *page = prepared_pages[i];
59                 fault_in_pages_readable(buf, count);
60
61                 /* Copy data from userspace to the current page */
62                 kmap(page);
63                 page_fault = __copy_from_user(page_address(page) + offset,
64                                               buf, count);
65                 /* Flush processor's dcache for this page */
66                 flush_dcache_page(page);
67                 kunmap(page);
68                 buf += count;
69                 write_bytes -= count;
70
71                 if (page_fault)
72                         break;
73         }
74         return page_fault ? -EFAULT : 0;
75 }
76
77 /*
78  * unlocks pages after btrfs_file_write is done with them
79  */
80 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
81 {
82         size_t i;
83         for (i = 0; i < num_pages; i++) {
84                 if (!pages[i])
85                         break;
86                 /* page checked is some magic around finding pages that
87                  * have been modified without going through btrfs_set_page_dirty
88                  * clear it here
89                  */
90                 ClearPageChecked(pages[i]);
91                 unlock_page(pages[i]);
92                 mark_page_accessed(pages[i]);
93                 page_cache_release(pages[i]);
94         }
95 }
96
97 /*
98  * after copy_from_user, pages need to be dirtied and we need to make
99  * sure holes are created between the current EOF and the start of
100  * any next extents (if required).
101  *
102  * this also makes the decision about creating an inline extent vs
103  * doing real data extents, marking pages dirty and delalloc as required.
104  */
105 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
106                                    struct btrfs_root *root,
107                                    struct file *file,
108                                    struct page **pages,
109                                    size_t num_pages,
110                                    loff_t pos,
111                                    size_t write_bytes)
112 {
113         int err = 0;
114         int i;
115         struct inode *inode = fdentry(file)->d_inode;
116         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
117         u64 hint_byte;
118         u64 num_bytes;
119         u64 start_pos;
120         u64 end_of_last_block;
121         u64 end_pos = pos + write_bytes;
122         loff_t isize = i_size_read(inode);
123
124         start_pos = pos & ~((u64)root->sectorsize - 1);
125         num_bytes = (write_bytes + pos - start_pos +
126                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
127
128         end_of_last_block = start_pos + num_bytes - 1;
129
130         lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
131         trans = btrfs_join_transaction(root, 1);
132         if (!trans) {
133                 err = -ENOMEM;
134                 goto out_unlock;
135         }
136         btrfs_set_trans_block_group(trans, inode);
137         hint_byte = 0;
138
139         set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
140
141         /* check for reserved extents on each page, we don't want
142          * to reset the delalloc bit on things that already have
143          * extents reserved.
144          */
145         btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
146         for (i = 0; i < num_pages; i++) {
147                 struct page *p = pages[i];
148                 SetPageUptodate(p);
149                 ClearPageChecked(p);
150                 set_page_dirty(p);
151         }
152         if (end_pos > isize) {
153                 i_size_write(inode, end_pos);
154                 btrfs_update_inode(trans, root, inode);
155         }
156         err = btrfs_end_transaction(trans, root);
157 out_unlock:
158         unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
159         return err;
160 }
161
162 /*
163  * this drops all the extents in the cache that intersect the range
164  * [start, end].  Existing extents are split as required.
165  */
166 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
167                             int skip_pinned)
168 {
169         struct extent_map *em;
170         struct extent_map *split = NULL;
171         struct extent_map *split2 = NULL;
172         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
173         u64 len = end - start + 1;
174         int ret;
175         int testend = 1;
176         unsigned long flags;
177         int compressed = 0;
178
179         WARN_ON(end < start);
180         if (end == (u64)-1) {
181                 len = (u64)-1;
182                 testend = 0;
183         }
184         while (1) {
185                 if (!split)
186                         split = alloc_extent_map(GFP_NOFS);
187                 if (!split2)
188                         split2 = alloc_extent_map(GFP_NOFS);
189
190                 spin_lock(&em_tree->lock);
191                 em = lookup_extent_mapping(em_tree, start, len);
192                 if (!em) {
193                         spin_unlock(&em_tree->lock);
194                         break;
195                 }
196                 flags = em->flags;
197                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
198                         spin_unlock(&em_tree->lock);
199                         if (em->start <= start &&
200                             (!testend || em->start + em->len >= start + len)) {
201                                 free_extent_map(em);
202                                 break;
203                         }
204                         if (start < em->start) {
205                                 len = em->start - start;
206                         } else {
207                                 len = start + len - (em->start + em->len);
208                                 start = em->start + em->len;
209                         }
210                         free_extent_map(em);
211                         continue;
212                 }
213                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
214                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
215                 remove_extent_mapping(em_tree, em);
216
217                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
218                     em->start < start) {
219                         split->start = em->start;
220                         split->len = start - em->start;
221                         split->orig_start = em->orig_start;
222                         split->block_start = em->block_start;
223
224                         if (compressed)
225                                 split->block_len = em->block_len;
226                         else
227                                 split->block_len = split->len;
228
229                         split->bdev = em->bdev;
230                         split->flags = flags;
231                         ret = add_extent_mapping(em_tree, split);
232                         BUG_ON(ret);
233                         free_extent_map(split);
234                         split = split2;
235                         split2 = NULL;
236                 }
237                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
238                     testend && em->start + em->len > start + len) {
239                         u64 diff = start + len - em->start;
240
241                         split->start = start + len;
242                         split->len = em->start + em->len - (start + len);
243                         split->bdev = em->bdev;
244                         split->flags = flags;
245
246                         if (compressed) {
247                                 split->block_len = em->block_len;
248                                 split->block_start = em->block_start;
249                                 split->orig_start = em->orig_start;
250                         } else {
251                                 split->block_len = split->len;
252                                 split->block_start = em->block_start + diff;
253                                 split->orig_start = split->start;
254                         }
255
256                         ret = add_extent_mapping(em_tree, split);
257                         BUG_ON(ret);
258                         free_extent_map(split);
259                         split = NULL;
260                 }
261                 spin_unlock(&em_tree->lock);
262
263                 /* once for us */
264                 free_extent_map(em);
265                 /* once for the tree*/
266                 free_extent_map(em);
267         }
268         if (split)
269                 free_extent_map(split);
270         if (split2)
271                 free_extent_map(split2);
272         return 0;
273 }
274
275 /*
276  * this is very complex, but the basic idea is to drop all extents
277  * in the range start - end.  hint_block is filled in with a block number
278  * that would be a good hint to the block allocator for this file.
279  *
280  * If an extent intersects the range but is not entirely inside the range
281  * it is either truncated or split.  Anything entirely inside the range
282  * is deleted from the tree.
283  *
284  * inline_limit is used to tell this code which offsets in the file to keep
285  * if they contain inline extents.
286  */
287 noinline int btrfs_drop_extents(struct btrfs_trans_handle *trans,
288                        struct btrfs_root *root, struct inode *inode,
289                        u64 start, u64 end, u64 locked_end,
290                        u64 inline_limit, u64 *hint_byte)
291 {
292         u64 extent_end = 0;
293         u64 search_start = start;
294         u64 ram_bytes = 0;
295         u64 disk_bytenr = 0;
296         u64 orig_locked_end = locked_end;
297         u8 compression;
298         u8 encryption;
299         u16 other_encoding = 0;
300         struct extent_buffer *leaf;
301         struct btrfs_file_extent_item *extent;
302         struct btrfs_path *path;
303         struct btrfs_key key;
304         struct btrfs_file_extent_item old;
305         int keep;
306         int slot;
307         int bookend;
308         int found_type = 0;
309         int found_extent;
310         int found_inline;
311         int recow;
312         int ret;
313
314         inline_limit = 0;
315         btrfs_drop_extent_cache(inode, start, end - 1, 0);
316
317         path = btrfs_alloc_path();
318         if (!path)
319                 return -ENOMEM;
320         while (1) {
321                 recow = 0;
322                 btrfs_release_path(root, path);
323                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
324                                                search_start, -1);
325                 if (ret < 0)
326                         goto out;
327                 if (ret > 0) {
328                         if (path->slots[0] == 0) {
329                                 ret = 0;
330                                 goto out;
331                         }
332                         path->slots[0]--;
333                 }
334 next_slot:
335                 keep = 0;
336                 bookend = 0;
337                 found_extent = 0;
338                 found_inline = 0;
339                 compression = 0;
340                 encryption = 0;
341                 extent = NULL;
342                 leaf = path->nodes[0];
343                 slot = path->slots[0];
344                 ret = 0;
345                 btrfs_item_key_to_cpu(leaf, &key, slot);
346                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
347                     key.offset >= end) {
348                         goto out;
349                 }
350                 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
351                     key.objectid != inode->i_ino) {
352                         goto out;
353                 }
354                 if (recow) {
355                         search_start = max(key.offset, start);
356                         continue;
357                 }
358                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
359                         extent = btrfs_item_ptr(leaf, slot,
360                                                 struct btrfs_file_extent_item);
361                         found_type = btrfs_file_extent_type(leaf, extent);
362                         compression = btrfs_file_extent_compression(leaf,
363                                                                     extent);
364                         encryption = btrfs_file_extent_encryption(leaf,
365                                                                   extent);
366                         other_encoding = btrfs_file_extent_other_encoding(leaf,
367                                                                   extent);
368                         if (found_type == BTRFS_FILE_EXTENT_REG ||
369                             found_type == BTRFS_FILE_EXTENT_PREALLOC) {
370                                 extent_end =
371                                      btrfs_file_extent_disk_bytenr(leaf,
372                                                                    extent);
373                                 if (extent_end)
374                                         *hint_byte = extent_end;
375
376                                 extent_end = key.offset +
377                                      btrfs_file_extent_num_bytes(leaf, extent);
378                                 ram_bytes = btrfs_file_extent_ram_bytes(leaf,
379                                                                 extent);
380                                 found_extent = 1;
381                         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
382                                 found_inline = 1;
383                                 extent_end = key.offset +
384                                      btrfs_file_extent_inline_len(leaf, extent);
385                         }
386                 } else {
387                         extent_end = search_start;
388                 }
389
390                 /* we found nothing we can drop */
391                 if ((!found_extent && !found_inline) ||
392                     search_start >= extent_end) {
393                         int nextret;
394                         u32 nritems;
395                         nritems = btrfs_header_nritems(leaf);
396                         if (slot >= nritems - 1) {
397                                 nextret = btrfs_next_leaf(root, path);
398                                 if (nextret)
399                                         goto out;
400                                 recow = 1;
401                         } else {
402                                 path->slots[0]++;
403                         }
404                         goto next_slot;
405                 }
406
407                 if (end <= extent_end && start >= key.offset && found_inline)
408                         *hint_byte = EXTENT_MAP_INLINE;
409
410                 if (found_extent) {
411                         read_extent_buffer(leaf, &old, (unsigned long)extent,
412                                            sizeof(old));
413                 }
414
415                 if (end < extent_end && end >= key.offset) {
416                         bookend = 1;
417                         if (found_inline && start <= key.offset)
418                                 keep = 1;
419                 }
420
421                 if (bookend && found_extent) {
422                         if (locked_end < extent_end) {
423                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
424                                                 locked_end, extent_end - 1,
425                                                 GFP_NOFS);
426                                 if (!ret) {
427                                         btrfs_release_path(root, path);
428                                         lock_extent(&BTRFS_I(inode)->io_tree,
429                                                 locked_end, extent_end - 1,
430                                                 GFP_NOFS);
431                                         locked_end = extent_end;
432                                         continue;
433                                 }
434                                 locked_end = extent_end;
435                         }
436                         disk_bytenr = le64_to_cpu(old.disk_bytenr);
437                         if (disk_bytenr != 0) {
438                                 ret = btrfs_inc_extent_ref(trans, root,
439                                            disk_bytenr,
440                                            le64_to_cpu(old.disk_num_bytes), 0,
441                                            root->root_key.objectid,
442                                            key.objectid, key.offset -
443                                            le64_to_cpu(old.offset));
444                                 BUG_ON(ret);
445                         }
446                 }
447
448                 if (found_inline) {
449                         u64 mask = root->sectorsize - 1;
450                         search_start = (extent_end + mask) & ~mask;
451                 } else
452                         search_start = extent_end;
453
454                 /* truncate existing extent */
455                 if (start > key.offset) {
456                         u64 new_num;
457                         u64 old_num;
458                         keep = 1;
459                         WARN_ON(start & (root->sectorsize - 1));
460                         if (found_extent) {
461                                 new_num = start - key.offset;
462                                 old_num = btrfs_file_extent_num_bytes(leaf,
463                                                                       extent);
464                                 *hint_byte =
465                                         btrfs_file_extent_disk_bytenr(leaf,
466                                                                       extent);
467                                 if (btrfs_file_extent_disk_bytenr(leaf,
468                                                                   extent)) {
469                                         inode_sub_bytes(inode, old_num -
470                                                         new_num);
471                                 }
472                                 btrfs_set_file_extent_num_bytes(leaf,
473                                                         extent, new_num);
474                                 btrfs_mark_buffer_dirty(leaf);
475                         } else if (key.offset < inline_limit &&
476                                    (end > extent_end) &&
477                                    (inline_limit < extent_end)) {
478                                 u32 new_size;
479                                 new_size = btrfs_file_extent_calc_inline_size(
480                                                    inline_limit - key.offset);
481                                 inode_sub_bytes(inode, extent_end -
482                                                 inline_limit);
483                                 btrfs_set_file_extent_ram_bytes(leaf, extent,
484                                                         new_size);
485                                 if (!compression && !encryption) {
486                                         btrfs_truncate_item(trans, root, path,
487                                                             new_size, 1);
488                                 }
489                         }
490                 }
491                 /* delete the entire extent */
492                 if (!keep) {
493                         if (found_inline)
494                                 inode_sub_bytes(inode, extent_end -
495                                                 key.offset);
496                         ret = btrfs_del_item(trans, root, path);
497                         /* TODO update progress marker and return */
498                         BUG_ON(ret);
499                         extent = NULL;
500                         btrfs_release_path(root, path);
501                         /* the extent will be freed later */
502                 }
503                 if (bookend && found_inline && start <= key.offset) {
504                         u32 new_size;
505                         new_size = btrfs_file_extent_calc_inline_size(
506                                                    extent_end - end);
507                         inode_sub_bytes(inode, end - key.offset);
508                         btrfs_set_file_extent_ram_bytes(leaf, extent,
509                                                         new_size);
510                         if (!compression && !encryption)
511                                 ret = btrfs_truncate_item(trans, root, path,
512                                                           new_size, 0);
513                         BUG_ON(ret);
514                 }
515                 /* create bookend, splitting the extent in two */
516                 if (bookend && found_extent) {
517                         struct btrfs_key ins;
518                         ins.objectid = inode->i_ino;
519                         ins.offset = end;
520                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
521
522                         btrfs_release_path(root, path);
523                         path->leave_spinning = 1;
524                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
525                                                       sizeof(*extent));
526                         BUG_ON(ret);
527
528                         leaf = path->nodes[0];
529                         extent = btrfs_item_ptr(leaf, path->slots[0],
530                                                 struct btrfs_file_extent_item);
531                         write_extent_buffer(leaf, &old,
532                                             (unsigned long)extent, sizeof(old));
533
534                         btrfs_set_file_extent_compression(leaf, extent,
535                                                           compression);
536                         btrfs_set_file_extent_encryption(leaf, extent,
537                                                          encryption);
538                         btrfs_set_file_extent_other_encoding(leaf, extent,
539                                                              other_encoding);
540                         btrfs_set_file_extent_offset(leaf, extent,
541                                     le64_to_cpu(old.offset) + end - key.offset);
542                         WARN_ON(le64_to_cpu(old.num_bytes) <
543                                 (extent_end - end));
544                         btrfs_set_file_extent_num_bytes(leaf, extent,
545                                                         extent_end - end);
546
547                         /*
548                          * set the ram bytes to the size of the full extent
549                          * before splitting.  This is a worst case flag,
550                          * but its the best we can do because we don't know
551                          * how splitting affects compression
552                          */
553                         btrfs_set_file_extent_ram_bytes(leaf, extent,
554                                                         ram_bytes);
555                         btrfs_set_file_extent_type(leaf, extent, found_type);
556
557                         btrfs_unlock_up_safe(path, 1);
558                         btrfs_mark_buffer_dirty(path->nodes[0]);
559                         btrfs_set_lock_blocking(path->nodes[0]);
560
561                         path->leave_spinning = 0;
562                         btrfs_release_path(root, path);
563                         if (disk_bytenr != 0)
564                                 inode_add_bytes(inode, extent_end - end);
565                 }
566
567                 if (found_extent && !keep) {
568                         u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
569
570                         if (old_disk_bytenr != 0) {
571                                 inode_sub_bytes(inode,
572                                                 le64_to_cpu(old.num_bytes));
573                                 ret = btrfs_free_extent(trans, root,
574                                                 old_disk_bytenr,
575                                                 le64_to_cpu(old.disk_num_bytes),
576                                                 0, root->root_key.objectid,
577                                                 key.objectid, key.offset -
578                                                 le64_to_cpu(old.offset));
579                                 BUG_ON(ret);
580                                 *hint_byte = old_disk_bytenr;
581                         }
582                 }
583
584                 if (search_start >= end) {
585                         ret = 0;
586                         goto out;
587                 }
588         }
589 out:
590         btrfs_free_path(path);
591         if (locked_end > orig_locked_end) {
592                 unlock_extent(&BTRFS_I(inode)->io_tree, orig_locked_end,
593                               locked_end - 1, GFP_NOFS);
594         }
595         return ret;
596 }
597
598 static int extent_mergeable(struct extent_buffer *leaf, int slot,
599                             u64 objectid, u64 bytenr, u64 *start, u64 *end)
600 {
601         struct btrfs_file_extent_item *fi;
602         struct btrfs_key key;
603         u64 extent_end;
604
605         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
606                 return 0;
607
608         btrfs_item_key_to_cpu(leaf, &key, slot);
609         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
610                 return 0;
611
612         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
613         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
614             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
615             btrfs_file_extent_compression(leaf, fi) ||
616             btrfs_file_extent_encryption(leaf, fi) ||
617             btrfs_file_extent_other_encoding(leaf, fi))
618                 return 0;
619
620         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
621         if ((*start && *start != key.offset) || (*end && *end != extent_end))
622                 return 0;
623
624         *start = key.offset;
625         *end = extent_end;
626         return 1;
627 }
628
629 /*
630  * Mark extent in the range start - end as written.
631  *
632  * This changes extent type from 'pre-allocated' to 'regular'. If only
633  * part of extent is marked as written, the extent will be split into
634  * two or three.
635  */
636 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
637                               struct btrfs_root *root,
638                               struct inode *inode, u64 start, u64 end)
639 {
640         struct extent_buffer *leaf;
641         struct btrfs_path *path;
642         struct btrfs_file_extent_item *fi;
643         struct btrfs_key key;
644         u64 bytenr;
645         u64 num_bytes;
646         u64 extent_end;
647         u64 orig_offset;
648         u64 other_start;
649         u64 other_end;
650         u64 split = start;
651         u64 locked_end = end;
652         int extent_type;
653         int split_end = 1;
654         int ret;
655
656         btrfs_drop_extent_cache(inode, start, end - 1, 0);
657
658         path = btrfs_alloc_path();
659         BUG_ON(!path);
660 again:
661         key.objectid = inode->i_ino;
662         key.type = BTRFS_EXTENT_DATA_KEY;
663         if (split == start)
664                 key.offset = split;
665         else
666                 key.offset = split - 1;
667
668         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
669         if (ret > 0 && path->slots[0] > 0)
670                 path->slots[0]--;
671
672         leaf = path->nodes[0];
673         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
674         BUG_ON(key.objectid != inode->i_ino ||
675                key.type != BTRFS_EXTENT_DATA_KEY);
676         fi = btrfs_item_ptr(leaf, path->slots[0],
677                             struct btrfs_file_extent_item);
678         extent_type = btrfs_file_extent_type(leaf, fi);
679         BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
680         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
681         BUG_ON(key.offset > start || extent_end < end);
682
683         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
684         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
685         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
686
687         if (key.offset == start)
688                 split = end;
689
690         if (key.offset == start && extent_end == end) {
691                 int del_nr = 0;
692                 int del_slot = 0;
693                 other_start = end;
694                 other_end = 0;
695                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
696                                      bytenr, &other_start, &other_end)) {
697                         extent_end = other_end;
698                         del_slot = path->slots[0] + 1;
699                         del_nr++;
700                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
701                                                 0, root->root_key.objectid,
702                                                 inode->i_ino, orig_offset);
703                         BUG_ON(ret);
704                 }
705                 other_start = 0;
706                 other_end = start;
707                 if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
708                                      bytenr, &other_start, &other_end)) {
709                         key.offset = other_start;
710                         del_slot = path->slots[0];
711                         del_nr++;
712                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
713                                                 0, root->root_key.objectid,
714                                                 inode->i_ino, orig_offset);
715                         BUG_ON(ret);
716                 }
717                 split_end = 0;
718                 if (del_nr == 0) {
719                         btrfs_set_file_extent_type(leaf, fi,
720                                                    BTRFS_FILE_EXTENT_REG);
721                         goto done;
722                 }
723
724                 fi = btrfs_item_ptr(leaf, del_slot - 1,
725                                     struct btrfs_file_extent_item);
726                 btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
727                 btrfs_set_file_extent_num_bytes(leaf, fi,
728                                                 extent_end - key.offset);
729                 btrfs_mark_buffer_dirty(leaf);
730
731                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
732                 BUG_ON(ret);
733                 goto release;
734         } else if (split == start) {
735                 if (locked_end < extent_end) {
736                         ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
737                                         locked_end, extent_end - 1, GFP_NOFS);
738                         if (!ret) {
739                                 btrfs_release_path(root, path);
740                                 lock_extent(&BTRFS_I(inode)->io_tree,
741                                         locked_end, extent_end - 1, GFP_NOFS);
742                                 locked_end = extent_end;
743                                 goto again;
744                         }
745                         locked_end = extent_end;
746                 }
747                 btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
748         } else  {
749                 BUG_ON(key.offset != start);
750                 key.offset = split;
751                 btrfs_set_file_extent_offset(leaf, fi, key.offset -
752                                              orig_offset);
753                 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
754                 btrfs_set_item_key_safe(trans, root, path, &key);
755                 extent_end = split;
756         }
757
758         if (extent_end == end) {
759                 split_end = 0;
760                 extent_type = BTRFS_FILE_EXTENT_REG;
761         }
762         if (extent_end == end && split == start) {
763                 other_start = end;
764                 other_end = 0;
765                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
766                                      bytenr, &other_start, &other_end)) {
767                         path->slots[0]++;
768                         fi = btrfs_item_ptr(leaf, path->slots[0],
769                                             struct btrfs_file_extent_item);
770                         key.offset = split;
771                         btrfs_set_item_key_safe(trans, root, path, &key);
772                         btrfs_set_file_extent_offset(leaf, fi, key.offset -
773                                                      orig_offset);
774                         btrfs_set_file_extent_num_bytes(leaf, fi,
775                                                         other_end - split);
776                         goto done;
777                 }
778         }
779         if (extent_end == end && split == end) {
780                 other_start = 0;
781                 other_end = start;
782                 if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
783                                      bytenr, &other_start, &other_end)) {
784                         path->slots[0]--;
785                         fi = btrfs_item_ptr(leaf, path->slots[0],
786                                             struct btrfs_file_extent_item);
787                         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
788                                                         other_start);
789                         goto done;
790                 }
791         }
792
793         btrfs_mark_buffer_dirty(leaf);
794
795         ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
796                                    root->root_key.objectid,
797                                    inode->i_ino, orig_offset);
798         BUG_ON(ret);
799         btrfs_release_path(root, path);
800
801         key.offset = start;
802         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
803         BUG_ON(ret);
804
805         leaf = path->nodes[0];
806         fi = btrfs_item_ptr(leaf, path->slots[0],
807                             struct btrfs_file_extent_item);
808         btrfs_set_file_extent_generation(leaf, fi, trans->transid);
809         btrfs_set_file_extent_type(leaf, fi, extent_type);
810         btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
811         btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
812         btrfs_set_file_extent_offset(leaf, fi, key.offset - orig_offset);
813         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
814         btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
815         btrfs_set_file_extent_compression(leaf, fi, 0);
816         btrfs_set_file_extent_encryption(leaf, fi, 0);
817         btrfs_set_file_extent_other_encoding(leaf, fi, 0);
818 done:
819         btrfs_mark_buffer_dirty(leaf);
820
821 release:
822         btrfs_release_path(root, path);
823         if (split_end && split == start) {
824                 split = end;
825                 goto again;
826         }
827         if (locked_end > end) {
828                 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
829                               GFP_NOFS);
830         }
831         btrfs_free_path(path);
832         return 0;
833 }
834
835 /*
836  * this gets pages into the page cache and locks them down, it also properly
837  * waits for data=ordered extents to finish before allowing the pages to be
838  * modified.
839  */
840 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
841                          struct page **pages, size_t num_pages,
842                          loff_t pos, unsigned long first_index,
843                          unsigned long last_index, size_t write_bytes)
844 {
845         int i;
846         unsigned long index = pos >> PAGE_CACHE_SHIFT;
847         struct inode *inode = fdentry(file)->d_inode;
848         int err = 0;
849         u64 start_pos;
850         u64 last_pos;
851
852         start_pos = pos & ~((u64)root->sectorsize - 1);
853         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
854
855         if (start_pos > inode->i_size) {
856                 err = btrfs_cont_expand(inode, start_pos);
857                 if (err)
858                         return err;
859         }
860
861         memset(pages, 0, num_pages * sizeof(struct page *));
862 again:
863         for (i = 0; i < num_pages; i++) {
864                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
865                 if (!pages[i]) {
866                         err = -ENOMEM;
867                         BUG_ON(1);
868                 }
869                 wait_on_page_writeback(pages[i]);
870         }
871         if (start_pos < inode->i_size) {
872                 struct btrfs_ordered_extent *ordered;
873                 lock_extent(&BTRFS_I(inode)->io_tree,
874                             start_pos, last_pos - 1, GFP_NOFS);
875                 ordered = btrfs_lookup_first_ordered_extent(inode,
876                                                             last_pos - 1);
877                 if (ordered &&
878                     ordered->file_offset + ordered->len > start_pos &&
879                     ordered->file_offset < last_pos) {
880                         btrfs_put_ordered_extent(ordered);
881                         unlock_extent(&BTRFS_I(inode)->io_tree,
882                                       start_pos, last_pos - 1, GFP_NOFS);
883                         for (i = 0; i < num_pages; i++) {
884                                 unlock_page(pages[i]);
885                                 page_cache_release(pages[i]);
886                         }
887                         btrfs_wait_ordered_range(inode, start_pos,
888                                                  last_pos - start_pos);
889                         goto again;
890                 }
891                 if (ordered)
892                         btrfs_put_ordered_extent(ordered);
893
894                 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
895                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
896                                   GFP_NOFS);
897                 unlock_extent(&BTRFS_I(inode)->io_tree,
898                               start_pos, last_pos - 1, GFP_NOFS);
899         }
900         for (i = 0; i < num_pages; i++) {
901                 clear_page_dirty_for_io(pages[i]);
902                 set_page_extent_mapped(pages[i]);
903                 WARN_ON(!PageLocked(pages[i]));
904         }
905         return 0;
906 }
907
908 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
909                                 size_t count, loff_t *ppos)
910 {
911         loff_t pos;
912         loff_t start_pos;
913         ssize_t num_written = 0;
914         ssize_t err = 0;
915         int ret = 0;
916         struct inode *inode = fdentry(file)->d_inode;
917         struct btrfs_root *root = BTRFS_I(inode)->root;
918         struct page **pages = NULL;
919         int nrptrs;
920         struct page *pinned[2];
921         unsigned long first_index;
922         unsigned long last_index;
923         int will_write;
924
925         will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
926                       (file->f_flags & O_DIRECT));
927
928         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
929                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
930         pinned[0] = NULL;
931         pinned[1] = NULL;
932
933         pos = *ppos;
934         start_pos = pos;
935
936         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
937         current->backing_dev_info = inode->i_mapping->backing_dev_info;
938         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
939         if (err)
940                 goto out_nolock;
941         if (count == 0)
942                 goto out_nolock;
943
944         err = file_remove_suid(file);
945         if (err)
946                 goto out_nolock;
947         file_update_time(file);
948
949         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
950
951         mutex_lock(&inode->i_mutex);
952         BTRFS_I(inode)->sequence++;
953         first_index = pos >> PAGE_CACHE_SHIFT;
954         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
955
956         /*
957          * there are lots of better ways to do this, but this code
958          * makes sure the first and last page in the file range are
959          * up to date and ready for cow
960          */
961         if ((pos & (PAGE_CACHE_SIZE - 1))) {
962                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
963                 if (!PageUptodate(pinned[0])) {
964                         ret = btrfs_readpage(NULL, pinned[0]);
965                         BUG_ON(ret);
966                         wait_on_page_locked(pinned[0]);
967                 } else {
968                         unlock_page(pinned[0]);
969                 }
970         }
971         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
972                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
973                 if (!PageUptodate(pinned[1])) {
974                         ret = btrfs_readpage(NULL, pinned[1]);
975                         BUG_ON(ret);
976                         wait_on_page_locked(pinned[1]);
977                 } else {
978                         unlock_page(pinned[1]);
979                 }
980         }
981
982         while (count > 0) {
983                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
984                 size_t write_bytes = min(count, nrptrs *
985                                         (size_t)PAGE_CACHE_SIZE -
986                                          offset);
987                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
988                                         PAGE_CACHE_SHIFT;
989
990                 WARN_ON(num_pages > nrptrs);
991                 memset(pages, 0, sizeof(struct page *) * nrptrs);
992
993                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
994                 if (ret)
995                         goto out;
996
997                 ret = prepare_pages(root, file, pages, num_pages,
998                                     pos, first_index, last_index,
999                                     write_bytes);
1000                 if (ret) {
1001                         btrfs_free_reserved_data_space(root, inode,
1002                                                        write_bytes);
1003                         goto out;
1004                 }
1005
1006                 ret = btrfs_copy_from_user(pos, num_pages,
1007                                            write_bytes, pages, buf);
1008                 if (ret) {
1009                         btrfs_free_reserved_data_space(root, inode,
1010                                                        write_bytes);
1011                         btrfs_drop_pages(pages, num_pages);
1012                         goto out;
1013                 }
1014
1015                 ret = dirty_and_release_pages(NULL, root, file, pages,
1016                                               num_pages, pos, write_bytes);
1017                 btrfs_drop_pages(pages, num_pages);
1018                 if (ret) {
1019                         btrfs_free_reserved_data_space(root, inode,
1020                                                        write_bytes);
1021                         goto out;
1022                 }
1023
1024                 if (will_write) {
1025                         btrfs_fdatawrite_range(inode->i_mapping, pos,
1026                                                pos + write_bytes - 1,
1027                                                WB_SYNC_ALL);
1028                 } else {
1029                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1030                                                            num_pages);
1031                         if (num_pages <
1032                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1033                                 btrfs_btree_balance_dirty(root, 1);
1034                         btrfs_throttle(root);
1035                 }
1036
1037                 buf += write_bytes;
1038                 count -= write_bytes;
1039                 pos += write_bytes;
1040                 num_written += write_bytes;
1041
1042                 cond_resched();
1043         }
1044 out:
1045         mutex_unlock(&inode->i_mutex);
1046         if (ret)
1047                 err = ret;
1048
1049 out_nolock:
1050         kfree(pages);
1051         if (pinned[0])
1052                 page_cache_release(pinned[0]);
1053         if (pinned[1])
1054                 page_cache_release(pinned[1]);
1055         *ppos = pos;
1056
1057         /*
1058          * we want to make sure fsync finds this change
1059          * but we haven't joined a transaction running right now.
1060          *
1061          * Later on, someone is sure to update the inode and get the
1062          * real transid recorded.
1063          *
1064          * We set last_trans now to the fs_info generation + 1,
1065          * this will either be one more than the running transaction
1066          * or the generation used for the next transaction if there isn't
1067          * one running right now.
1068          */
1069         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1070
1071         if (num_written > 0 && will_write) {
1072                 struct btrfs_trans_handle *trans;
1073
1074                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1075                 if (err)
1076                         num_written = err;
1077
1078                 if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
1079                         trans = btrfs_start_transaction(root, 1);
1080                         ret = btrfs_log_dentry_safe(trans, root,
1081                                                     file->f_dentry);
1082                         if (ret == 0) {
1083                                 ret = btrfs_sync_log(trans, root);
1084                                 if (ret == 0)
1085                                         btrfs_end_transaction(trans, root);
1086                                 else
1087                                         btrfs_commit_transaction(trans, root);
1088                         } else {
1089                                 btrfs_commit_transaction(trans, root);
1090                         }
1091                 }
1092                 if (file->f_flags & O_DIRECT) {
1093                         invalidate_mapping_pages(inode->i_mapping,
1094                               start_pos >> PAGE_CACHE_SHIFT,
1095                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1096                 }
1097         }
1098         current->backing_dev_info = NULL;
1099         return num_written ? num_written : err;
1100 }
1101
1102 int btrfs_release_file(struct inode *inode, struct file *filp)
1103 {
1104         /*
1105          * ordered_data_close is set by settattr when we are about to truncate
1106          * a file from a non-zero size to a zero size.  This tries to
1107          * flush down new bytes that may have been written if the
1108          * application were using truncate to replace a file in place.
1109          */
1110         if (BTRFS_I(inode)->ordered_data_close) {
1111                 BTRFS_I(inode)->ordered_data_close = 0;
1112                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1113                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1114                         filemap_flush(inode->i_mapping);
1115         }
1116         if (filp->private_data)
1117                 btrfs_ioctl_trans_end(filp);
1118         return 0;
1119 }
1120
1121 /*
1122  * fsync call for both files and directories.  This logs the inode into
1123  * the tree log instead of forcing full commits whenever possible.
1124  *
1125  * It needs to call filemap_fdatawait so that all ordered extent updates are
1126  * in the metadata btree are up to date for copying to the log.
1127  *
1128  * It drops the inode mutex before doing the tree log commit.  This is an
1129  * important optimization for directories because holding the mutex prevents
1130  * new operations on the dir while we write to disk.
1131  */
1132 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1133 {
1134         struct inode *inode = dentry->d_inode;
1135         struct btrfs_root *root = BTRFS_I(inode)->root;
1136         int ret = 0;
1137         struct btrfs_trans_handle *trans;
1138
1139         /*
1140          * check the transaction that last modified this inode
1141          * and see if its already been committed
1142          */
1143         if (!BTRFS_I(inode)->last_trans)
1144                 goto out;
1145
1146         mutex_lock(&root->fs_info->trans_mutex);
1147         if (BTRFS_I(inode)->last_trans <=
1148             root->fs_info->last_trans_committed) {
1149                 BTRFS_I(inode)->last_trans = 0;
1150                 mutex_unlock(&root->fs_info->trans_mutex);
1151                 goto out;
1152         }
1153         mutex_unlock(&root->fs_info->trans_mutex);
1154
1155         root->log_batch++;
1156         filemap_fdatawrite(inode->i_mapping);
1157         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1158         root->log_batch++;
1159
1160         /*
1161          * ok we haven't committed the transaction yet, lets do a commit
1162          */
1163         if (file && file->private_data)
1164                 btrfs_ioctl_trans_end(file);
1165
1166         trans = btrfs_start_transaction(root, 1);
1167         if (!trans) {
1168                 ret = -ENOMEM;
1169                 goto out;
1170         }
1171
1172         ret = btrfs_log_dentry_safe(trans, root, dentry);
1173         if (ret < 0)
1174                 goto out;
1175
1176         /* we've logged all the items and now have a consistent
1177          * version of the file in the log.  It is possible that
1178          * someone will come in and modify the file, but that's
1179          * fine because the log is consistent on disk, and we
1180          * have references to all of the file's extents
1181          *
1182          * It is possible that someone will come in and log the
1183          * file again, but that will end up using the synchronization
1184          * inside btrfs_sync_log to keep things safe.
1185          */
1186         mutex_unlock(&dentry->d_inode->i_mutex);
1187
1188         if (ret > 0) {
1189                 ret = btrfs_commit_transaction(trans, root);
1190         } else {
1191                 ret = btrfs_sync_log(trans, root);
1192                 if (ret == 0)
1193                         ret = btrfs_end_transaction(trans, root);
1194                 else
1195                         ret = btrfs_commit_transaction(trans, root);
1196         }
1197         mutex_lock(&dentry->d_inode->i_mutex);
1198 out:
1199         return ret > 0 ? EIO : ret;
1200 }
1201
1202 static struct vm_operations_struct btrfs_file_vm_ops = {
1203         .fault          = filemap_fault,
1204         .page_mkwrite   = btrfs_page_mkwrite,
1205 };
1206
1207 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1208 {
1209         vma->vm_ops = &btrfs_file_vm_ops;
1210         file_accessed(filp);
1211         return 0;
1212 }
1213
1214 struct file_operations btrfs_file_operations = {
1215         .llseek         = generic_file_llseek,
1216         .read           = do_sync_read,
1217         .aio_read       = generic_file_aio_read,
1218         .splice_read    = generic_file_splice_read,
1219         .write          = btrfs_file_write,
1220         .mmap           = btrfs_file_mmap,
1221         .open           = generic_file_open,
1222         .release        = btrfs_release_file,
1223         .fsync          = btrfs_sync_file,
1224         .unlocked_ioctl = btrfs_ioctl,
1225 #ifdef CONFIG_COMPAT
1226         .compat_ioctl   = btrfs_ioctl,
1227 #endif
1228 };