Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable
[sfrench/cifs-2.6.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/backing-dev.h>
26 #include <linux/mpage.h>
27 #include <linux/swap.h>
28 #include <linux/writeback.h>
29 #include <linux/statfs.h>
30 #include <linux/compat.h>
31 #include "ctree.h"
32 #include "disk-io.h"
33 #include "transaction.h"
34 #include "btrfs_inode.h"
35 #include "ioctl.h"
36 #include "print-tree.h"
37 #include "tree-log.h"
38 #include "locking.h"
39 #include "compat.h"
40
41
42 /* simple helper to fault in pages and copy.  This should go away
43  * and be replaced with calls into generic code.
44  */
45 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
46                                          int write_bytes,
47                                          struct page **prepared_pages,
48                                          const char __user *buf)
49 {
50         long page_fault = 0;
51         int i;
52         int offset = pos & (PAGE_CACHE_SIZE - 1);
53
54         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
55                 size_t count = min_t(size_t,
56                                      PAGE_CACHE_SIZE - offset, write_bytes);
57                 struct page *page = prepared_pages[i];
58                 fault_in_pages_readable(buf, count);
59
60                 /* Copy data from userspace to the current page */
61                 kmap(page);
62                 page_fault = __copy_from_user(page_address(page) + offset,
63                                               buf, count);
64                 /* Flush processor's dcache for this page */
65                 flush_dcache_page(page);
66                 kunmap(page);
67                 buf += count;
68                 write_bytes -= count;
69
70                 if (page_fault)
71                         break;
72         }
73         return page_fault ? -EFAULT : 0;
74 }
75
76 /*
77  * unlocks pages after btrfs_file_write is done with them
78  */
79 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
80 {
81         size_t i;
82         for (i = 0; i < num_pages; i++) {
83                 if (!pages[i])
84                         break;
85                 /* page checked is some magic around finding pages that
86                  * have been modified without going through btrfs_set_page_dirty
87                  * clear it here
88                  */
89                 ClearPageChecked(pages[i]);
90                 unlock_page(pages[i]);
91                 mark_page_accessed(pages[i]);
92                 page_cache_release(pages[i]);
93         }
94 }
95
96 /*
97  * after copy_from_user, pages need to be dirtied and we need to make
98  * sure holes are created between the current EOF and the start of
99  * any next extents (if required).
100  *
101  * this also makes the decision about creating an inline extent vs
102  * doing real data extents, marking pages dirty and delalloc as required.
103  */
104 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
105                                    struct btrfs_root *root,
106                                    struct file *file,
107                                    struct page **pages,
108                                    size_t num_pages,
109                                    loff_t pos,
110                                    size_t write_bytes)
111 {
112         int err = 0;
113         int i;
114         struct inode *inode = fdentry(file)->d_inode;
115         u64 num_bytes;
116         u64 start_pos;
117         u64 end_of_last_block;
118         u64 end_pos = pos + write_bytes;
119         loff_t isize = i_size_read(inode);
120
121         start_pos = pos & ~((u64)root->sectorsize - 1);
122         num_bytes = (write_bytes + pos - start_pos +
123                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
124
125         end_of_last_block = start_pos + num_bytes - 1;
126         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
127         if (err)
128                 return err;
129
130         for (i = 0; i < num_pages; i++) {
131                 struct page *p = pages[i];
132                 SetPageUptodate(p);
133                 ClearPageChecked(p);
134                 set_page_dirty(p);
135         }
136         if (end_pos > isize) {
137                 i_size_write(inode, end_pos);
138                 /* we've only changed i_size in ram, and we haven't updated
139                  * the disk i_size.  There is no need to log the inode
140                  * at this time.
141                  */
142         }
143         return err;
144 }
145
146 /*
147  * this drops all the extents in the cache that intersect the range
148  * [start, end].  Existing extents are split as required.
149  */
150 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
151                             int skip_pinned)
152 {
153         struct extent_map *em;
154         struct extent_map *split = NULL;
155         struct extent_map *split2 = NULL;
156         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
157         u64 len = end - start + 1;
158         int ret;
159         int testend = 1;
160         unsigned long flags;
161         int compressed = 0;
162
163         WARN_ON(end < start);
164         if (end == (u64)-1) {
165                 len = (u64)-1;
166                 testend = 0;
167         }
168         while (1) {
169                 if (!split)
170                         split = alloc_extent_map(GFP_NOFS);
171                 if (!split2)
172                         split2 = alloc_extent_map(GFP_NOFS);
173
174                 write_lock(&em_tree->lock);
175                 em = lookup_extent_mapping(em_tree, start, len);
176                 if (!em) {
177                         write_unlock(&em_tree->lock);
178                         break;
179                 }
180                 flags = em->flags;
181                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
182                         if (testend && em->start + em->len >= start + len) {
183                                 free_extent_map(em);
184                                 write_unlock(&em_tree->lock);
185                                 break;
186                         }
187                         start = em->start + em->len;
188                         if (testend)
189                                 len = start + len - (em->start + em->len);
190                         free_extent_map(em);
191                         write_unlock(&em_tree->lock);
192                         continue;
193                 }
194                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
195                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
196                 remove_extent_mapping(em_tree, em);
197
198                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
199                     em->start < start) {
200                         split->start = em->start;
201                         split->len = start - em->start;
202                         split->orig_start = em->orig_start;
203                         split->block_start = em->block_start;
204
205                         if (compressed)
206                                 split->block_len = em->block_len;
207                         else
208                                 split->block_len = split->len;
209
210                         split->bdev = em->bdev;
211                         split->flags = flags;
212                         ret = add_extent_mapping(em_tree, split);
213                         BUG_ON(ret);
214                         free_extent_map(split);
215                         split = split2;
216                         split2 = NULL;
217                 }
218                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
219                     testend && em->start + em->len > start + len) {
220                         u64 diff = start + len - em->start;
221
222                         split->start = start + len;
223                         split->len = em->start + em->len - (start + len);
224                         split->bdev = em->bdev;
225                         split->flags = flags;
226
227                         if (compressed) {
228                                 split->block_len = em->block_len;
229                                 split->block_start = em->block_start;
230                                 split->orig_start = em->orig_start;
231                         } else {
232                                 split->block_len = split->len;
233                                 split->block_start = em->block_start + diff;
234                                 split->orig_start = split->start;
235                         }
236
237                         ret = add_extent_mapping(em_tree, split);
238                         BUG_ON(ret);
239                         free_extent_map(split);
240                         split = NULL;
241                 }
242                 write_unlock(&em_tree->lock);
243
244                 /* once for us */
245                 free_extent_map(em);
246                 /* once for the tree*/
247                 free_extent_map(em);
248         }
249         if (split)
250                 free_extent_map(split);
251         if (split2)
252                 free_extent_map(split2);
253         return 0;
254 }
255
256 /*
257  * this is very complex, but the basic idea is to drop all extents
258  * in the range start - end.  hint_block is filled in with a block number
259  * that would be a good hint to the block allocator for this file.
260  *
261  * If an extent intersects the range but is not entirely inside the range
262  * it is either truncated or split.  Anything entirely inside the range
263  * is deleted from the tree.
264  */
265 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
266                        u64 start, u64 end, u64 *hint_byte, int drop_cache)
267 {
268         struct btrfs_root *root = BTRFS_I(inode)->root;
269         struct extent_buffer *leaf;
270         struct btrfs_file_extent_item *fi;
271         struct btrfs_path *path;
272         struct btrfs_key key;
273         struct btrfs_key new_key;
274         u64 search_start = start;
275         u64 disk_bytenr = 0;
276         u64 num_bytes = 0;
277         u64 extent_offset = 0;
278         u64 extent_end = 0;
279         int del_nr = 0;
280         int del_slot = 0;
281         int extent_type;
282         int recow;
283         int ret;
284
285         if (drop_cache)
286                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
287
288         path = btrfs_alloc_path();
289         if (!path)
290                 return -ENOMEM;
291
292         while (1) {
293                 recow = 0;
294                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
295                                                search_start, -1);
296                 if (ret < 0)
297                         break;
298                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
299                         leaf = path->nodes[0];
300                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
301                         if (key.objectid == inode->i_ino &&
302                             key.type == BTRFS_EXTENT_DATA_KEY)
303                                 path->slots[0]--;
304                 }
305                 ret = 0;
306 next_slot:
307                 leaf = path->nodes[0];
308                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
309                         BUG_ON(del_nr > 0);
310                         ret = btrfs_next_leaf(root, path);
311                         if (ret < 0)
312                                 break;
313                         if (ret > 0) {
314                                 ret = 0;
315                                 break;
316                         }
317                         leaf = path->nodes[0];
318                         recow = 1;
319                 }
320
321                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
322                 if (key.objectid > inode->i_ino ||
323                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
324                         break;
325
326                 fi = btrfs_item_ptr(leaf, path->slots[0],
327                                     struct btrfs_file_extent_item);
328                 extent_type = btrfs_file_extent_type(leaf, fi);
329
330                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
331                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
332                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
333                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
334                         extent_offset = btrfs_file_extent_offset(leaf, fi);
335                         extent_end = key.offset +
336                                 btrfs_file_extent_num_bytes(leaf, fi);
337                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
338                         extent_end = key.offset +
339                                 btrfs_file_extent_inline_len(leaf, fi);
340                 } else {
341                         WARN_ON(1);
342                         extent_end = search_start;
343                 }
344
345                 if (extent_end <= search_start) {
346                         path->slots[0]++;
347                         goto next_slot;
348                 }
349
350                 search_start = max(key.offset, start);
351                 if (recow) {
352                         btrfs_release_path(root, path);
353                         continue;
354                 }
355
356                 /*
357                  *     | - range to drop - |
358                  *  | -------- extent -------- |
359                  */
360                 if (start > key.offset && end < extent_end) {
361                         BUG_ON(del_nr > 0);
362                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
363
364                         memcpy(&new_key, &key, sizeof(new_key));
365                         new_key.offset = start;
366                         ret = btrfs_duplicate_item(trans, root, path,
367                                                    &new_key);
368                         if (ret == -EAGAIN) {
369                                 btrfs_release_path(root, path);
370                                 continue;
371                         }
372                         if (ret < 0)
373                                 break;
374
375                         leaf = path->nodes[0];
376                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
377                                             struct btrfs_file_extent_item);
378                         btrfs_set_file_extent_num_bytes(leaf, fi,
379                                                         start - key.offset);
380
381                         fi = btrfs_item_ptr(leaf, path->slots[0],
382                                             struct btrfs_file_extent_item);
383
384                         extent_offset += start - key.offset;
385                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
386                         btrfs_set_file_extent_num_bytes(leaf, fi,
387                                                         extent_end - start);
388                         btrfs_mark_buffer_dirty(leaf);
389
390                         if (disk_bytenr > 0) {
391                                 ret = btrfs_inc_extent_ref(trans, root,
392                                                 disk_bytenr, num_bytes, 0,
393                                                 root->root_key.objectid,
394                                                 new_key.objectid,
395                                                 start - extent_offset);
396                                 BUG_ON(ret);
397                                 *hint_byte = disk_bytenr;
398                         }
399                         key.offset = start;
400                 }
401                 /*
402                  *  | ---- range to drop ----- |
403                  *      | -------- extent -------- |
404                  */
405                 if (start <= key.offset && end < extent_end) {
406                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
407
408                         memcpy(&new_key, &key, sizeof(new_key));
409                         new_key.offset = end;
410                         btrfs_set_item_key_safe(trans, root, path, &new_key);
411
412                         extent_offset += end - key.offset;
413                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
414                         btrfs_set_file_extent_num_bytes(leaf, fi,
415                                                         extent_end - end);
416                         btrfs_mark_buffer_dirty(leaf);
417                         if (disk_bytenr > 0) {
418                                 inode_sub_bytes(inode, end - key.offset);
419                                 *hint_byte = disk_bytenr;
420                         }
421                         break;
422                 }
423
424                 search_start = extent_end;
425                 /*
426                  *       | ---- range to drop ----- |
427                  *  | -------- extent -------- |
428                  */
429                 if (start > key.offset && end >= extent_end) {
430                         BUG_ON(del_nr > 0);
431                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
432
433                         btrfs_set_file_extent_num_bytes(leaf, fi,
434                                                         start - key.offset);
435                         btrfs_mark_buffer_dirty(leaf);
436                         if (disk_bytenr > 0) {
437                                 inode_sub_bytes(inode, extent_end - start);
438                                 *hint_byte = disk_bytenr;
439                         }
440                         if (end == extent_end)
441                                 break;
442
443                         path->slots[0]++;
444                         goto next_slot;
445                 }
446
447                 /*
448                  *  | ---- range to drop ----- |
449                  *    | ------ extent ------ |
450                  */
451                 if (start <= key.offset && end >= extent_end) {
452                         if (del_nr == 0) {
453                                 del_slot = path->slots[0];
454                                 del_nr = 1;
455                         } else {
456                                 BUG_ON(del_slot + del_nr != path->slots[0]);
457                                 del_nr++;
458                         }
459
460                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
461                                 inode_sub_bytes(inode,
462                                                 extent_end - key.offset);
463                                 extent_end = ALIGN(extent_end,
464                                                    root->sectorsize);
465                         } else if (disk_bytenr > 0) {
466                                 ret = btrfs_free_extent(trans, root,
467                                                 disk_bytenr, num_bytes, 0,
468                                                 root->root_key.objectid,
469                                                 key.objectid, key.offset -
470                                                 extent_offset);
471                                 BUG_ON(ret);
472                                 inode_sub_bytes(inode,
473                                                 extent_end - key.offset);
474                                 *hint_byte = disk_bytenr;
475                         }
476
477                         if (end == extent_end)
478                                 break;
479
480                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
481                                 path->slots[0]++;
482                                 goto next_slot;
483                         }
484
485                         ret = btrfs_del_items(trans, root, path, del_slot,
486                                               del_nr);
487                         BUG_ON(ret);
488
489                         del_nr = 0;
490                         del_slot = 0;
491
492                         btrfs_release_path(root, path);
493                         continue;
494                 }
495
496                 BUG_ON(1);
497         }
498
499         if (del_nr > 0) {
500                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
501                 BUG_ON(ret);
502         }
503
504         btrfs_free_path(path);
505         return ret;
506 }
507
508 static int extent_mergeable(struct extent_buffer *leaf, int slot,
509                             u64 objectid, u64 bytenr, u64 orig_offset,
510                             u64 *start, u64 *end)
511 {
512         struct btrfs_file_extent_item *fi;
513         struct btrfs_key key;
514         u64 extent_end;
515
516         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
517                 return 0;
518
519         btrfs_item_key_to_cpu(leaf, &key, slot);
520         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
521                 return 0;
522
523         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
524         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
525             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
526             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
527             btrfs_file_extent_compression(leaf, fi) ||
528             btrfs_file_extent_encryption(leaf, fi) ||
529             btrfs_file_extent_other_encoding(leaf, fi))
530                 return 0;
531
532         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
533         if ((*start && *start != key.offset) || (*end && *end != extent_end))
534                 return 0;
535
536         *start = key.offset;
537         *end = extent_end;
538         return 1;
539 }
540
541 /*
542  * Mark extent in the range start - end as written.
543  *
544  * This changes extent type from 'pre-allocated' to 'regular'. If only
545  * part of extent is marked as written, the extent will be split into
546  * two or three.
547  */
548 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
549                               struct inode *inode, u64 start, u64 end)
550 {
551         struct btrfs_root *root = BTRFS_I(inode)->root;
552         struct extent_buffer *leaf;
553         struct btrfs_path *path;
554         struct btrfs_file_extent_item *fi;
555         struct btrfs_key key;
556         struct btrfs_key new_key;
557         u64 bytenr;
558         u64 num_bytes;
559         u64 extent_end;
560         u64 orig_offset;
561         u64 other_start;
562         u64 other_end;
563         u64 split;
564         int del_nr = 0;
565         int del_slot = 0;
566         int recow;
567         int ret;
568
569         btrfs_drop_extent_cache(inode, start, end - 1, 0);
570
571         path = btrfs_alloc_path();
572         BUG_ON(!path);
573 again:
574         recow = 0;
575         split = start;
576         key.objectid = inode->i_ino;
577         key.type = BTRFS_EXTENT_DATA_KEY;
578         key.offset = split;
579
580         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
581         if (ret > 0 && path->slots[0] > 0)
582                 path->slots[0]--;
583
584         leaf = path->nodes[0];
585         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
586         BUG_ON(key.objectid != inode->i_ino ||
587                key.type != BTRFS_EXTENT_DATA_KEY);
588         fi = btrfs_item_ptr(leaf, path->slots[0],
589                             struct btrfs_file_extent_item);
590         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
591                BTRFS_FILE_EXTENT_PREALLOC);
592         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
593         BUG_ON(key.offset > start || extent_end < end);
594
595         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
596         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
597         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
598         memcpy(&new_key, &key, sizeof(new_key));
599
600         if (start == key.offset && end < extent_end) {
601                 other_start = 0;
602                 other_end = start;
603                 if (extent_mergeable(leaf, path->slots[0] - 1,
604                                      inode->i_ino, bytenr, orig_offset,
605                                      &other_start, &other_end)) {
606                         new_key.offset = end;
607                         btrfs_set_item_key_safe(trans, root, path, &new_key);
608                         fi = btrfs_item_ptr(leaf, path->slots[0],
609                                             struct btrfs_file_extent_item);
610                         btrfs_set_file_extent_num_bytes(leaf, fi,
611                                                         extent_end - end);
612                         btrfs_set_file_extent_offset(leaf, fi,
613                                                      end - orig_offset);
614                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
615                                             struct btrfs_file_extent_item);
616                         btrfs_set_file_extent_num_bytes(leaf, fi,
617                                                         end - other_start);
618                         btrfs_mark_buffer_dirty(leaf);
619                         goto out;
620                 }
621         }
622
623         if (start > key.offset && end == extent_end) {
624                 other_start = end;
625                 other_end = 0;
626                 if (extent_mergeable(leaf, path->slots[0] + 1,
627                                      inode->i_ino, bytenr, orig_offset,
628                                      &other_start, &other_end)) {
629                         fi = btrfs_item_ptr(leaf, path->slots[0],
630                                             struct btrfs_file_extent_item);
631                         btrfs_set_file_extent_num_bytes(leaf, fi,
632                                                         start - key.offset);
633                         path->slots[0]++;
634                         new_key.offset = start;
635                         btrfs_set_item_key_safe(trans, root, path, &new_key);
636
637                         fi = btrfs_item_ptr(leaf, path->slots[0],
638                                             struct btrfs_file_extent_item);
639                         btrfs_set_file_extent_num_bytes(leaf, fi,
640                                                         other_end - start);
641                         btrfs_set_file_extent_offset(leaf, fi,
642                                                      start - orig_offset);
643                         btrfs_mark_buffer_dirty(leaf);
644                         goto out;
645                 }
646         }
647
648         while (start > key.offset || end < extent_end) {
649                 if (key.offset == start)
650                         split = end;
651
652                 new_key.offset = split;
653                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
654                 if (ret == -EAGAIN) {
655                         btrfs_release_path(root, path);
656                         goto again;
657                 }
658                 BUG_ON(ret < 0);
659
660                 leaf = path->nodes[0];
661                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
662                                     struct btrfs_file_extent_item);
663                 btrfs_set_file_extent_num_bytes(leaf, fi,
664                                                 split - key.offset);
665
666                 fi = btrfs_item_ptr(leaf, path->slots[0],
667                                     struct btrfs_file_extent_item);
668
669                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
670                 btrfs_set_file_extent_num_bytes(leaf, fi,
671                                                 extent_end - split);
672                 btrfs_mark_buffer_dirty(leaf);
673
674                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
675                                            root->root_key.objectid,
676                                            inode->i_ino, orig_offset);
677                 BUG_ON(ret);
678
679                 if (split == start) {
680                         key.offset = start;
681                 } else {
682                         BUG_ON(start != key.offset);
683                         path->slots[0]--;
684                         extent_end = end;
685                 }
686                 recow = 1;
687         }
688
689         other_start = end;
690         other_end = 0;
691         if (extent_mergeable(leaf, path->slots[0] + 1,
692                              inode->i_ino, bytenr, orig_offset,
693                              &other_start, &other_end)) {
694                 if (recow) {
695                         btrfs_release_path(root, path);
696                         goto again;
697                 }
698                 extent_end = other_end;
699                 del_slot = path->slots[0] + 1;
700                 del_nr++;
701                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
702                                         0, root->root_key.objectid,
703                                         inode->i_ino, orig_offset);
704                 BUG_ON(ret);
705         }
706         other_start = 0;
707         other_end = start;
708         if (extent_mergeable(leaf, path->slots[0] - 1,
709                              inode->i_ino, bytenr, orig_offset,
710                              &other_start, &other_end)) {
711                 if (recow) {
712                         btrfs_release_path(root, path);
713                         goto again;
714                 }
715                 key.offset = other_start;
716                 del_slot = path->slots[0];
717                 del_nr++;
718                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
719                                         0, root->root_key.objectid,
720                                         inode->i_ino, orig_offset);
721                 BUG_ON(ret);
722         }
723         if (del_nr == 0) {
724                 fi = btrfs_item_ptr(leaf, path->slots[0],
725                            struct btrfs_file_extent_item);
726                 btrfs_set_file_extent_type(leaf, fi,
727                                            BTRFS_FILE_EXTENT_REG);
728                 btrfs_mark_buffer_dirty(leaf);
729         } else {
730                 fi = btrfs_item_ptr(leaf, del_slot - 1,
731                            struct btrfs_file_extent_item);
732                 btrfs_set_file_extent_type(leaf, fi,
733                                            BTRFS_FILE_EXTENT_REG);
734                 btrfs_set_file_extent_num_bytes(leaf, fi,
735                                                 extent_end - key.offset);
736                 btrfs_mark_buffer_dirty(leaf);
737
738                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
739                 BUG_ON(ret);
740         }
741 out:
742         btrfs_free_path(path);
743         return 0;
744 }
745
746 /*
747  * this gets pages into the page cache and locks them down, it also properly
748  * waits for data=ordered extents to finish before allowing the pages to be
749  * modified.
750  */
751 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
752                          struct page **pages, size_t num_pages,
753                          loff_t pos, unsigned long first_index,
754                          unsigned long last_index, size_t write_bytes)
755 {
756         int i;
757         unsigned long index = pos >> PAGE_CACHE_SHIFT;
758         struct inode *inode = fdentry(file)->d_inode;
759         int err = 0;
760         u64 start_pos;
761         u64 last_pos;
762
763         start_pos = pos & ~((u64)root->sectorsize - 1);
764         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
765
766         if (start_pos > inode->i_size) {
767                 err = btrfs_cont_expand(inode, start_pos);
768                 if (err)
769                         return err;
770         }
771
772         memset(pages, 0, num_pages * sizeof(struct page *));
773 again:
774         for (i = 0; i < num_pages; i++) {
775                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
776                 if (!pages[i]) {
777                         err = -ENOMEM;
778                         BUG_ON(1);
779                 }
780                 wait_on_page_writeback(pages[i]);
781         }
782         if (start_pos < inode->i_size) {
783                 struct btrfs_ordered_extent *ordered;
784                 lock_extent(&BTRFS_I(inode)->io_tree,
785                             start_pos, last_pos - 1, GFP_NOFS);
786                 ordered = btrfs_lookup_first_ordered_extent(inode,
787                                                             last_pos - 1);
788                 if (ordered &&
789                     ordered->file_offset + ordered->len > start_pos &&
790                     ordered->file_offset < last_pos) {
791                         btrfs_put_ordered_extent(ordered);
792                         unlock_extent(&BTRFS_I(inode)->io_tree,
793                                       start_pos, last_pos - 1, GFP_NOFS);
794                         for (i = 0; i < num_pages; i++) {
795                                 unlock_page(pages[i]);
796                                 page_cache_release(pages[i]);
797                         }
798                         btrfs_wait_ordered_range(inode, start_pos,
799                                                  last_pos - start_pos);
800                         goto again;
801                 }
802                 if (ordered)
803                         btrfs_put_ordered_extent(ordered);
804
805                 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
806                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
807                                   EXTENT_DO_ACCOUNTING,
808                                   GFP_NOFS);
809                 unlock_extent(&BTRFS_I(inode)->io_tree,
810                               start_pos, last_pos - 1, GFP_NOFS);
811         }
812         for (i = 0; i < num_pages; i++) {
813                 clear_page_dirty_for_io(pages[i]);
814                 set_page_extent_mapped(pages[i]);
815                 WARN_ON(!PageLocked(pages[i]));
816         }
817         return 0;
818 }
819
820 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
821                                 size_t count, loff_t *ppos)
822 {
823         loff_t pos;
824         loff_t start_pos;
825         ssize_t num_written = 0;
826         ssize_t err = 0;
827         int ret = 0;
828         struct inode *inode = fdentry(file)->d_inode;
829         struct btrfs_root *root = BTRFS_I(inode)->root;
830         struct page **pages = NULL;
831         int nrptrs;
832         struct page *pinned[2];
833         unsigned long first_index;
834         unsigned long last_index;
835         int will_write;
836
837         will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) ||
838                       (file->f_flags & O_DIRECT));
839
840         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
841                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
842         pinned[0] = NULL;
843         pinned[1] = NULL;
844
845         pos = *ppos;
846         start_pos = pos;
847
848         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
849
850         /* do the reserve before the mutex lock in case we have to do some
851          * flushing.  We wouldn't deadlock, but this is more polite.
852          */
853         err = btrfs_reserve_metadata_for_delalloc(root, inode, 1);
854         if (err)
855                 goto out_nolock;
856
857         mutex_lock(&inode->i_mutex);
858
859         current->backing_dev_info = inode->i_mapping->backing_dev_info;
860         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
861         if (err)
862                 goto out;
863
864         if (count == 0)
865                 goto out;
866
867         err = file_remove_suid(file);
868         if (err)
869                 goto out;
870
871         file_update_time(file);
872
873         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
874
875         /* generic_write_checks can change our pos */
876         start_pos = pos;
877
878         BTRFS_I(inode)->sequence++;
879         first_index = pos >> PAGE_CACHE_SHIFT;
880         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
881
882         /*
883          * there are lots of better ways to do this, but this code
884          * makes sure the first and last page in the file range are
885          * up to date and ready for cow
886          */
887         if ((pos & (PAGE_CACHE_SIZE - 1))) {
888                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
889                 if (!PageUptodate(pinned[0])) {
890                         ret = btrfs_readpage(NULL, pinned[0]);
891                         BUG_ON(ret);
892                         wait_on_page_locked(pinned[0]);
893                 } else {
894                         unlock_page(pinned[0]);
895                 }
896         }
897         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
898                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
899                 if (!PageUptodate(pinned[1])) {
900                         ret = btrfs_readpage(NULL, pinned[1]);
901                         BUG_ON(ret);
902                         wait_on_page_locked(pinned[1]);
903                 } else {
904                         unlock_page(pinned[1]);
905                 }
906         }
907
908         while (count > 0) {
909                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
910                 size_t write_bytes = min(count, nrptrs *
911                                         (size_t)PAGE_CACHE_SIZE -
912                                          offset);
913                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
914                                         PAGE_CACHE_SHIFT;
915
916                 WARN_ON(num_pages > nrptrs);
917                 memset(pages, 0, sizeof(struct page *) * nrptrs);
918
919                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
920                 if (ret)
921                         goto out;
922
923                 ret = prepare_pages(root, file, pages, num_pages,
924                                     pos, first_index, last_index,
925                                     write_bytes);
926                 if (ret) {
927                         btrfs_free_reserved_data_space(root, inode,
928                                                        write_bytes);
929                         goto out;
930                 }
931
932                 ret = btrfs_copy_from_user(pos, num_pages,
933                                            write_bytes, pages, buf);
934                 if (ret) {
935                         btrfs_free_reserved_data_space(root, inode,
936                                                        write_bytes);
937                         btrfs_drop_pages(pages, num_pages);
938                         goto out;
939                 }
940
941                 ret = dirty_and_release_pages(NULL, root, file, pages,
942                                               num_pages, pos, write_bytes);
943                 btrfs_drop_pages(pages, num_pages);
944                 if (ret) {
945                         btrfs_free_reserved_data_space(root, inode,
946                                                        write_bytes);
947                         goto out;
948                 }
949
950                 if (will_write) {
951                         filemap_fdatawrite_range(inode->i_mapping, pos,
952                                                  pos + write_bytes - 1);
953                 } else {
954                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
955                                                            num_pages);
956                         if (num_pages <
957                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
958                                 btrfs_btree_balance_dirty(root, 1);
959                         btrfs_throttle(root);
960                 }
961
962                 buf += write_bytes;
963                 count -= write_bytes;
964                 pos += write_bytes;
965                 num_written += write_bytes;
966
967                 cond_resched();
968         }
969 out:
970         mutex_unlock(&inode->i_mutex);
971         if (ret)
972                 err = ret;
973         btrfs_unreserve_metadata_for_delalloc(root, inode, 1);
974
975 out_nolock:
976         kfree(pages);
977         if (pinned[0])
978                 page_cache_release(pinned[0]);
979         if (pinned[1])
980                 page_cache_release(pinned[1]);
981         *ppos = pos;
982
983         /*
984          * we want to make sure fsync finds this change
985          * but we haven't joined a transaction running right now.
986          *
987          * Later on, someone is sure to update the inode and get the
988          * real transid recorded.
989          *
990          * We set last_trans now to the fs_info generation + 1,
991          * this will either be one more than the running transaction
992          * or the generation used for the next transaction if there isn't
993          * one running right now.
994          */
995         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
996
997         if (num_written > 0 && will_write) {
998                 struct btrfs_trans_handle *trans;
999
1000                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1001                 if (err)
1002                         num_written = err;
1003
1004                 if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
1005                         trans = btrfs_start_transaction(root, 1);
1006                         ret = btrfs_log_dentry_safe(trans, root,
1007                                                     file->f_dentry);
1008                         if (ret == 0) {
1009                                 ret = btrfs_sync_log(trans, root);
1010                                 if (ret == 0)
1011                                         btrfs_end_transaction(trans, root);
1012                                 else
1013                                         btrfs_commit_transaction(trans, root);
1014                         } else if (ret != BTRFS_NO_LOG_SYNC) {
1015                                 btrfs_commit_transaction(trans, root);
1016                         } else {
1017                                 btrfs_end_transaction(trans, root);
1018                         }
1019                 }
1020                 if (file->f_flags & O_DIRECT) {
1021                         invalidate_mapping_pages(inode->i_mapping,
1022                               start_pos >> PAGE_CACHE_SHIFT,
1023                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1024                 }
1025         }
1026         current->backing_dev_info = NULL;
1027         return num_written ? num_written : err;
1028 }
1029
1030 int btrfs_release_file(struct inode *inode, struct file *filp)
1031 {
1032         /*
1033          * ordered_data_close is set by settattr when we are about to truncate
1034          * a file from a non-zero size to a zero size.  This tries to
1035          * flush down new bytes that may have been written if the
1036          * application were using truncate to replace a file in place.
1037          */
1038         if (BTRFS_I(inode)->ordered_data_close) {
1039                 BTRFS_I(inode)->ordered_data_close = 0;
1040                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1041                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1042                         filemap_flush(inode->i_mapping);
1043         }
1044         if (filp->private_data)
1045                 btrfs_ioctl_trans_end(filp);
1046         return 0;
1047 }
1048
1049 /*
1050  * fsync call for both files and directories.  This logs the inode into
1051  * the tree log instead of forcing full commits whenever possible.
1052  *
1053  * It needs to call filemap_fdatawait so that all ordered extent updates are
1054  * in the metadata btree are up to date for copying to the log.
1055  *
1056  * It drops the inode mutex before doing the tree log commit.  This is an
1057  * important optimization for directories because holding the mutex prevents
1058  * new operations on the dir while we write to disk.
1059  */
1060 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1061 {
1062         struct inode *inode = dentry->d_inode;
1063         struct btrfs_root *root = BTRFS_I(inode)->root;
1064         int ret = 0;
1065         struct btrfs_trans_handle *trans;
1066
1067
1068         /* we wait first, since the writeback may change the inode */
1069         root->log_batch++;
1070         /* the VFS called filemap_fdatawrite for us */
1071         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1072         root->log_batch++;
1073
1074         /*
1075          * check the transaction that last modified this inode
1076          * and see if its already been committed
1077          */
1078         if (!BTRFS_I(inode)->last_trans)
1079                 goto out;
1080
1081         /*
1082          * if the last transaction that changed this file was before
1083          * the current transaction, we can bail out now without any
1084          * syncing
1085          */
1086         mutex_lock(&root->fs_info->trans_mutex);
1087         if (BTRFS_I(inode)->last_trans <=
1088             root->fs_info->last_trans_committed) {
1089                 BTRFS_I(inode)->last_trans = 0;
1090                 mutex_unlock(&root->fs_info->trans_mutex);
1091                 goto out;
1092         }
1093         mutex_unlock(&root->fs_info->trans_mutex);
1094
1095         /*
1096          * ok we haven't committed the transaction yet, lets do a commit
1097          */
1098         if (file && file->private_data)
1099                 btrfs_ioctl_trans_end(file);
1100
1101         trans = btrfs_start_transaction(root, 1);
1102         if (!trans) {
1103                 ret = -ENOMEM;
1104                 goto out;
1105         }
1106
1107         ret = btrfs_log_dentry_safe(trans, root, dentry);
1108         if (ret < 0)
1109                 goto out;
1110
1111         /* we've logged all the items and now have a consistent
1112          * version of the file in the log.  It is possible that
1113          * someone will come in and modify the file, but that's
1114          * fine because the log is consistent on disk, and we
1115          * have references to all of the file's extents
1116          *
1117          * It is possible that someone will come in and log the
1118          * file again, but that will end up using the synchronization
1119          * inside btrfs_sync_log to keep things safe.
1120          */
1121         mutex_unlock(&dentry->d_inode->i_mutex);
1122
1123         if (ret != BTRFS_NO_LOG_SYNC) {
1124                 if (ret > 0) {
1125                         ret = btrfs_commit_transaction(trans, root);
1126                 } else {
1127                         ret = btrfs_sync_log(trans, root);
1128                         if (ret == 0)
1129                                 ret = btrfs_end_transaction(trans, root);
1130                         else
1131                                 ret = btrfs_commit_transaction(trans, root);
1132                 }
1133         } else {
1134                 ret = btrfs_end_transaction(trans, root);
1135         }
1136         mutex_lock(&dentry->d_inode->i_mutex);
1137 out:
1138         return ret > 0 ? -EIO : ret;
1139 }
1140
1141 static const struct vm_operations_struct btrfs_file_vm_ops = {
1142         .fault          = filemap_fault,
1143         .page_mkwrite   = btrfs_page_mkwrite,
1144 };
1145
1146 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1147 {
1148         vma->vm_ops = &btrfs_file_vm_ops;
1149         file_accessed(filp);
1150         return 0;
1151 }
1152
1153 const struct file_operations btrfs_file_operations = {
1154         .llseek         = generic_file_llseek,
1155         .read           = do_sync_read,
1156         .aio_read       = generic_file_aio_read,
1157         .splice_read    = generic_file_splice_read,
1158         .write          = btrfs_file_write,
1159         .mmap           = btrfs_file_mmap,
1160         .open           = generic_file_open,
1161         .release        = btrfs_release_file,
1162         .fsync          = btrfs_sync_file,
1163         .unlocked_ioctl = btrfs_ioctl,
1164 #ifdef CONFIG_COMPAT
1165         .compat_ioctl   = btrfs_ioctl,
1166 #endif
1167 };