Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
[linux-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 <linux/slab.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                                          struct iov_iter *i)
50 {
51         size_t copied = 0;
52         int pg = 0;
53         int offset = pos & (PAGE_CACHE_SIZE - 1);
54         int total_copied = 0;
55
56         while (write_bytes > 0) {
57                 size_t count = min_t(size_t,
58                                      PAGE_CACHE_SIZE - offset, write_bytes);
59                 struct page *page = prepared_pages[pg];
60                 /*
61                  * Copy data from userspace to the current page
62                  *
63                  * Disable pagefault to avoid recursive lock since
64                  * the pages are already locked
65                  */
66                 pagefault_disable();
67                 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
68                 pagefault_enable();
69
70                 /* Flush processor's dcache for this page */
71                 flush_dcache_page(page);
72                 iov_iter_advance(i, copied);
73                 write_bytes -= copied;
74                 total_copied += copied;
75
76                 /* Return to btrfs_file_aio_write to fault page */
77                 if (unlikely(copied == 0)) {
78                         break;
79                 }
80
81                 if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
82                         offset += copied;
83                 } else {
84                         pg++;
85                         offset = 0;
86                 }
87         }
88         return total_copied;
89 }
90
91 /*
92  * unlocks pages after btrfs_file_write is done with them
93  */
94 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
95 {
96         size_t i;
97         for (i = 0; i < num_pages; i++) {
98                 if (!pages[i])
99                         break;
100                 /* page checked is some magic around finding pages that
101                  * have been modified without going through btrfs_set_page_dirty
102                  * clear it here
103                  */
104                 ClearPageChecked(pages[i]);
105                 unlock_page(pages[i]);
106                 mark_page_accessed(pages[i]);
107                 page_cache_release(pages[i]);
108         }
109 }
110
111 /*
112  * after copy_from_user, pages need to be dirtied and we need to make
113  * sure holes are created between the current EOF and the start of
114  * any next extents (if required).
115  *
116  * this also makes the decision about creating an inline extent vs
117  * doing real data extents, marking pages dirty and delalloc as required.
118  */
119 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
120                                    struct btrfs_root *root,
121                                    struct file *file,
122                                    struct page **pages,
123                                    size_t num_pages,
124                                    loff_t pos,
125                                    size_t write_bytes)
126 {
127         int err = 0;
128         int i;
129         struct inode *inode = fdentry(file)->d_inode;
130         u64 num_bytes;
131         u64 start_pos;
132         u64 end_of_last_block;
133         u64 end_pos = pos + write_bytes;
134         loff_t isize = i_size_read(inode);
135
136         start_pos = pos & ~((u64)root->sectorsize - 1);
137         num_bytes = (write_bytes + pos - start_pos +
138                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
139
140         end_of_last_block = start_pos + num_bytes - 1;
141         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
142                                         NULL);
143         BUG_ON(err);
144
145         for (i = 0; i < num_pages; i++) {
146                 struct page *p = pages[i];
147                 SetPageUptodate(p);
148                 ClearPageChecked(p);
149                 set_page_dirty(p);
150         }
151         if (end_pos > isize) {
152                 i_size_write(inode, end_pos);
153                 /* we've only changed i_size in ram, and we haven't updated
154                  * the disk i_size.  There is no need to log the inode
155                  * at this time.
156                  */
157         }
158         return 0;
159 }
160
161 /*
162  * this drops all the extents in the cache that intersect the range
163  * [start, end].  Existing extents are split as required.
164  */
165 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
166                             int skip_pinned)
167 {
168         struct extent_map *em;
169         struct extent_map *split = NULL;
170         struct extent_map *split2 = NULL;
171         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
172         u64 len = end - start + 1;
173         int ret;
174         int testend = 1;
175         unsigned long flags;
176         int compressed = 0;
177
178         WARN_ON(end < start);
179         if (end == (u64)-1) {
180                 len = (u64)-1;
181                 testend = 0;
182         }
183         while (1) {
184                 if (!split)
185                         split = alloc_extent_map(GFP_NOFS);
186                 if (!split2)
187                         split2 = alloc_extent_map(GFP_NOFS);
188
189                 write_lock(&em_tree->lock);
190                 em = lookup_extent_mapping(em_tree, start, len);
191                 if (!em) {
192                         write_unlock(&em_tree->lock);
193                         break;
194                 }
195                 flags = em->flags;
196                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
197                         if (testend && em->start + em->len >= start + len) {
198                                 free_extent_map(em);
199                                 write_unlock(&em_tree->lock);
200                                 break;
201                         }
202                         start = em->start + em->len;
203                         if (testend)
204                                 len = start + len - (em->start + em->len);
205                         free_extent_map(em);
206                         write_unlock(&em_tree->lock);
207                         continue;
208                 }
209                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
210                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
211                 remove_extent_mapping(em_tree, em);
212
213                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
214                     em->start < start) {
215                         split->start = em->start;
216                         split->len = start - em->start;
217                         split->orig_start = em->orig_start;
218                         split->block_start = em->block_start;
219
220                         if (compressed)
221                                 split->block_len = em->block_len;
222                         else
223                                 split->block_len = split->len;
224
225                         split->bdev = em->bdev;
226                         split->flags = flags;
227                         ret = add_extent_mapping(em_tree, split);
228                         BUG_ON(ret);
229                         free_extent_map(split);
230                         split = split2;
231                         split2 = NULL;
232                 }
233                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
234                     testend && em->start + em->len > start + len) {
235                         u64 diff = start + len - em->start;
236
237                         split->start = start + len;
238                         split->len = em->start + em->len - (start + len);
239                         split->bdev = em->bdev;
240                         split->flags = flags;
241
242                         if (compressed) {
243                                 split->block_len = em->block_len;
244                                 split->block_start = em->block_start;
245                                 split->orig_start = em->orig_start;
246                         } else {
247                                 split->block_len = split->len;
248                                 split->block_start = em->block_start + diff;
249                                 split->orig_start = split->start;
250                         }
251
252                         ret = add_extent_mapping(em_tree, split);
253                         BUG_ON(ret);
254                         free_extent_map(split);
255                         split = NULL;
256                 }
257                 write_unlock(&em_tree->lock);
258
259                 /* once for us */
260                 free_extent_map(em);
261                 /* once for the tree*/
262                 free_extent_map(em);
263         }
264         if (split)
265                 free_extent_map(split);
266         if (split2)
267                 free_extent_map(split2);
268         return 0;
269 }
270
271 /*
272  * this is very complex, but the basic idea is to drop all extents
273  * in the range start - end.  hint_block is filled in with a block number
274  * that would be a good hint to the block allocator for this file.
275  *
276  * If an extent intersects the range but is not entirely inside the range
277  * it is either truncated or split.  Anything entirely inside the range
278  * is deleted from the tree.
279  */
280 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
281                        u64 start, u64 end, u64 *hint_byte, int drop_cache)
282 {
283         struct btrfs_root *root = BTRFS_I(inode)->root;
284         struct extent_buffer *leaf;
285         struct btrfs_file_extent_item *fi;
286         struct btrfs_path *path;
287         struct btrfs_key key;
288         struct btrfs_key new_key;
289         u64 search_start = start;
290         u64 disk_bytenr = 0;
291         u64 num_bytes = 0;
292         u64 extent_offset = 0;
293         u64 extent_end = 0;
294         int del_nr = 0;
295         int del_slot = 0;
296         int extent_type;
297         int recow;
298         int ret;
299
300         if (drop_cache)
301                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
302
303         path = btrfs_alloc_path();
304         if (!path)
305                 return -ENOMEM;
306
307         while (1) {
308                 recow = 0;
309                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
310                                                search_start, -1);
311                 if (ret < 0)
312                         break;
313                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
314                         leaf = path->nodes[0];
315                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
316                         if (key.objectid == inode->i_ino &&
317                             key.type == BTRFS_EXTENT_DATA_KEY)
318                                 path->slots[0]--;
319                 }
320                 ret = 0;
321 next_slot:
322                 leaf = path->nodes[0];
323                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
324                         BUG_ON(del_nr > 0);
325                         ret = btrfs_next_leaf(root, path);
326                         if (ret < 0)
327                                 break;
328                         if (ret > 0) {
329                                 ret = 0;
330                                 break;
331                         }
332                         leaf = path->nodes[0];
333                         recow = 1;
334                 }
335
336                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
337                 if (key.objectid > inode->i_ino ||
338                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
339                         break;
340
341                 fi = btrfs_item_ptr(leaf, path->slots[0],
342                                     struct btrfs_file_extent_item);
343                 extent_type = btrfs_file_extent_type(leaf, fi);
344
345                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
346                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
347                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
348                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
349                         extent_offset = btrfs_file_extent_offset(leaf, fi);
350                         extent_end = key.offset +
351                                 btrfs_file_extent_num_bytes(leaf, fi);
352                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
353                         extent_end = key.offset +
354                                 btrfs_file_extent_inline_len(leaf, fi);
355                 } else {
356                         WARN_ON(1);
357                         extent_end = search_start;
358                 }
359
360                 if (extent_end <= search_start) {
361                         path->slots[0]++;
362                         goto next_slot;
363                 }
364
365                 search_start = max(key.offset, start);
366                 if (recow) {
367                         btrfs_release_path(root, path);
368                         continue;
369                 }
370
371                 /*
372                  *     | - range to drop - |
373                  *  | -------- extent -------- |
374                  */
375                 if (start > key.offset && end < extent_end) {
376                         BUG_ON(del_nr > 0);
377                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
378
379                         memcpy(&new_key, &key, sizeof(new_key));
380                         new_key.offset = start;
381                         ret = btrfs_duplicate_item(trans, root, path,
382                                                    &new_key);
383                         if (ret == -EAGAIN) {
384                                 btrfs_release_path(root, path);
385                                 continue;
386                         }
387                         if (ret < 0)
388                                 break;
389
390                         leaf = path->nodes[0];
391                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
392                                             struct btrfs_file_extent_item);
393                         btrfs_set_file_extent_num_bytes(leaf, fi,
394                                                         start - key.offset);
395
396                         fi = btrfs_item_ptr(leaf, path->slots[0],
397                                             struct btrfs_file_extent_item);
398
399                         extent_offset += start - key.offset;
400                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
401                         btrfs_set_file_extent_num_bytes(leaf, fi,
402                                                         extent_end - start);
403                         btrfs_mark_buffer_dirty(leaf);
404
405                         if (disk_bytenr > 0) {
406                                 ret = btrfs_inc_extent_ref(trans, root,
407                                                 disk_bytenr, num_bytes, 0,
408                                                 root->root_key.objectid,
409                                                 new_key.objectid,
410                                                 start - extent_offset);
411                                 BUG_ON(ret);
412                                 *hint_byte = disk_bytenr;
413                         }
414                         key.offset = start;
415                 }
416                 /*
417                  *  | ---- range to drop ----- |
418                  *      | -------- extent -------- |
419                  */
420                 if (start <= key.offset && end < extent_end) {
421                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
422
423                         memcpy(&new_key, &key, sizeof(new_key));
424                         new_key.offset = end;
425                         btrfs_set_item_key_safe(trans, root, path, &new_key);
426
427                         extent_offset += end - key.offset;
428                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
429                         btrfs_set_file_extent_num_bytes(leaf, fi,
430                                                         extent_end - end);
431                         btrfs_mark_buffer_dirty(leaf);
432                         if (disk_bytenr > 0) {
433                                 inode_sub_bytes(inode, end - key.offset);
434                                 *hint_byte = disk_bytenr;
435                         }
436                         break;
437                 }
438
439                 search_start = extent_end;
440                 /*
441                  *       | ---- range to drop ----- |
442                  *  | -------- extent -------- |
443                  */
444                 if (start > key.offset && end >= extent_end) {
445                         BUG_ON(del_nr > 0);
446                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
447
448                         btrfs_set_file_extent_num_bytes(leaf, fi,
449                                                         start - key.offset);
450                         btrfs_mark_buffer_dirty(leaf);
451                         if (disk_bytenr > 0) {
452                                 inode_sub_bytes(inode, extent_end - start);
453                                 *hint_byte = disk_bytenr;
454                         }
455                         if (end == extent_end)
456                                 break;
457
458                         path->slots[0]++;
459                         goto next_slot;
460                 }
461
462                 /*
463                  *  | ---- range to drop ----- |
464                  *    | ------ extent ------ |
465                  */
466                 if (start <= key.offset && end >= extent_end) {
467                         if (del_nr == 0) {
468                                 del_slot = path->slots[0];
469                                 del_nr = 1;
470                         } else {
471                                 BUG_ON(del_slot + del_nr != path->slots[0]);
472                                 del_nr++;
473                         }
474
475                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
476                                 inode_sub_bytes(inode,
477                                                 extent_end - key.offset);
478                                 extent_end = ALIGN(extent_end,
479                                                    root->sectorsize);
480                         } else if (disk_bytenr > 0) {
481                                 ret = btrfs_free_extent(trans, root,
482                                                 disk_bytenr, num_bytes, 0,
483                                                 root->root_key.objectid,
484                                                 key.objectid, key.offset -
485                                                 extent_offset);
486                                 BUG_ON(ret);
487                                 inode_sub_bytes(inode,
488                                                 extent_end - key.offset);
489                                 *hint_byte = disk_bytenr;
490                         }
491
492                         if (end == extent_end)
493                                 break;
494
495                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
496                                 path->slots[0]++;
497                                 goto next_slot;
498                         }
499
500                         ret = btrfs_del_items(trans, root, path, del_slot,
501                                               del_nr);
502                         BUG_ON(ret);
503
504                         del_nr = 0;
505                         del_slot = 0;
506
507                         btrfs_release_path(root, path);
508                         continue;
509                 }
510
511                 BUG_ON(1);
512         }
513
514         if (del_nr > 0) {
515                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
516                 BUG_ON(ret);
517         }
518
519         btrfs_free_path(path);
520         return ret;
521 }
522
523 static int extent_mergeable(struct extent_buffer *leaf, int slot,
524                             u64 objectid, u64 bytenr, u64 orig_offset,
525                             u64 *start, u64 *end)
526 {
527         struct btrfs_file_extent_item *fi;
528         struct btrfs_key key;
529         u64 extent_end;
530
531         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
532                 return 0;
533
534         btrfs_item_key_to_cpu(leaf, &key, slot);
535         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
536                 return 0;
537
538         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
539         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
540             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
541             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
542             btrfs_file_extent_compression(leaf, fi) ||
543             btrfs_file_extent_encryption(leaf, fi) ||
544             btrfs_file_extent_other_encoding(leaf, fi))
545                 return 0;
546
547         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
548         if ((*start && *start != key.offset) || (*end && *end != extent_end))
549                 return 0;
550
551         *start = key.offset;
552         *end = extent_end;
553         return 1;
554 }
555
556 /*
557  * Mark extent in the range start - end as written.
558  *
559  * This changes extent type from 'pre-allocated' to 'regular'. If only
560  * part of extent is marked as written, the extent will be split into
561  * two or three.
562  */
563 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
564                               struct inode *inode, u64 start, u64 end)
565 {
566         struct btrfs_root *root = BTRFS_I(inode)->root;
567         struct extent_buffer *leaf;
568         struct btrfs_path *path;
569         struct btrfs_file_extent_item *fi;
570         struct btrfs_key key;
571         struct btrfs_key new_key;
572         u64 bytenr;
573         u64 num_bytes;
574         u64 extent_end;
575         u64 orig_offset;
576         u64 other_start;
577         u64 other_end;
578         u64 split;
579         int del_nr = 0;
580         int del_slot = 0;
581         int recow;
582         int ret;
583
584         btrfs_drop_extent_cache(inode, start, end - 1, 0);
585
586         path = btrfs_alloc_path();
587         BUG_ON(!path);
588 again:
589         recow = 0;
590         split = start;
591         key.objectid = inode->i_ino;
592         key.type = BTRFS_EXTENT_DATA_KEY;
593         key.offset = split;
594
595         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
596         if (ret > 0 && path->slots[0] > 0)
597                 path->slots[0]--;
598
599         leaf = path->nodes[0];
600         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
601         BUG_ON(key.objectid != inode->i_ino ||
602                key.type != BTRFS_EXTENT_DATA_KEY);
603         fi = btrfs_item_ptr(leaf, path->slots[0],
604                             struct btrfs_file_extent_item);
605         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
606                BTRFS_FILE_EXTENT_PREALLOC);
607         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
608         BUG_ON(key.offset > start || extent_end < end);
609
610         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
611         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
612         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
613         memcpy(&new_key, &key, sizeof(new_key));
614
615         if (start == key.offset && end < extent_end) {
616                 other_start = 0;
617                 other_end = start;
618                 if (extent_mergeable(leaf, path->slots[0] - 1,
619                                      inode->i_ino, bytenr, orig_offset,
620                                      &other_start, &other_end)) {
621                         new_key.offset = end;
622                         btrfs_set_item_key_safe(trans, root, path, &new_key);
623                         fi = btrfs_item_ptr(leaf, path->slots[0],
624                                             struct btrfs_file_extent_item);
625                         btrfs_set_file_extent_num_bytes(leaf, fi,
626                                                         extent_end - end);
627                         btrfs_set_file_extent_offset(leaf, fi,
628                                                      end - orig_offset);
629                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
630                                             struct btrfs_file_extent_item);
631                         btrfs_set_file_extent_num_bytes(leaf, fi,
632                                                         end - other_start);
633                         btrfs_mark_buffer_dirty(leaf);
634                         goto out;
635                 }
636         }
637
638         if (start > key.offset && end == extent_end) {
639                 other_start = end;
640                 other_end = 0;
641                 if (extent_mergeable(leaf, path->slots[0] + 1,
642                                      inode->i_ino, bytenr, orig_offset,
643                                      &other_start, &other_end)) {
644                         fi = btrfs_item_ptr(leaf, path->slots[0],
645                                             struct btrfs_file_extent_item);
646                         btrfs_set_file_extent_num_bytes(leaf, fi,
647                                                         start - key.offset);
648                         path->slots[0]++;
649                         new_key.offset = start;
650                         btrfs_set_item_key_safe(trans, root, path, &new_key);
651
652                         fi = btrfs_item_ptr(leaf, path->slots[0],
653                                             struct btrfs_file_extent_item);
654                         btrfs_set_file_extent_num_bytes(leaf, fi,
655                                                         other_end - start);
656                         btrfs_set_file_extent_offset(leaf, fi,
657                                                      start - orig_offset);
658                         btrfs_mark_buffer_dirty(leaf);
659                         goto out;
660                 }
661         }
662
663         while (start > key.offset || end < extent_end) {
664                 if (key.offset == start)
665                         split = end;
666
667                 new_key.offset = split;
668                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
669                 if (ret == -EAGAIN) {
670                         btrfs_release_path(root, path);
671                         goto again;
672                 }
673                 BUG_ON(ret < 0);
674
675                 leaf = path->nodes[0];
676                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
677                                     struct btrfs_file_extent_item);
678                 btrfs_set_file_extent_num_bytes(leaf, fi,
679                                                 split - key.offset);
680
681                 fi = btrfs_item_ptr(leaf, path->slots[0],
682                                     struct btrfs_file_extent_item);
683
684                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
685                 btrfs_set_file_extent_num_bytes(leaf, fi,
686                                                 extent_end - split);
687                 btrfs_mark_buffer_dirty(leaf);
688
689                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
690                                            root->root_key.objectid,
691                                            inode->i_ino, orig_offset);
692                 BUG_ON(ret);
693
694                 if (split == start) {
695                         key.offset = start;
696                 } else {
697                         BUG_ON(start != key.offset);
698                         path->slots[0]--;
699                         extent_end = end;
700                 }
701                 recow = 1;
702         }
703
704         other_start = end;
705         other_end = 0;
706         if (extent_mergeable(leaf, path->slots[0] + 1,
707                              inode->i_ino, bytenr, orig_offset,
708                              &other_start, &other_end)) {
709                 if (recow) {
710                         btrfs_release_path(root, path);
711                         goto again;
712                 }
713                 extent_end = other_end;
714                 del_slot = path->slots[0] + 1;
715                 del_nr++;
716                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
717                                         0, root->root_key.objectid,
718                                         inode->i_ino, orig_offset);
719                 BUG_ON(ret);
720         }
721         other_start = 0;
722         other_end = start;
723         if (extent_mergeable(leaf, path->slots[0] - 1,
724                              inode->i_ino, bytenr, orig_offset,
725                              &other_start, &other_end)) {
726                 if (recow) {
727                         btrfs_release_path(root, path);
728                         goto again;
729                 }
730                 key.offset = other_start;
731                 del_slot = path->slots[0];
732                 del_nr++;
733                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
734                                         0, root->root_key.objectid,
735                                         inode->i_ino, orig_offset);
736                 BUG_ON(ret);
737         }
738         if (del_nr == 0) {
739                 fi = btrfs_item_ptr(leaf, path->slots[0],
740                            struct btrfs_file_extent_item);
741                 btrfs_set_file_extent_type(leaf, fi,
742                                            BTRFS_FILE_EXTENT_REG);
743                 btrfs_mark_buffer_dirty(leaf);
744         } else {
745                 fi = btrfs_item_ptr(leaf, del_slot - 1,
746                            struct btrfs_file_extent_item);
747                 btrfs_set_file_extent_type(leaf, fi,
748                                            BTRFS_FILE_EXTENT_REG);
749                 btrfs_set_file_extent_num_bytes(leaf, fi,
750                                                 extent_end - key.offset);
751                 btrfs_mark_buffer_dirty(leaf);
752
753                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
754                 BUG_ON(ret);
755         }
756 out:
757         btrfs_free_path(path);
758         return 0;
759 }
760
761 /*
762  * this gets pages into the page cache and locks them down, it also properly
763  * waits for data=ordered extents to finish before allowing the pages to be
764  * modified.
765  */
766 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
767                          struct page **pages, size_t num_pages,
768                          loff_t pos, unsigned long first_index,
769                          unsigned long last_index, size_t write_bytes)
770 {
771         struct extent_state *cached_state = NULL;
772         int i;
773         unsigned long index = pos >> PAGE_CACHE_SHIFT;
774         struct inode *inode = fdentry(file)->d_inode;
775         int err = 0;
776         u64 start_pos;
777         u64 last_pos;
778
779         start_pos = pos & ~((u64)root->sectorsize - 1);
780         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
781
782         if (start_pos > inode->i_size) {
783                 err = btrfs_cont_expand(inode, start_pos);
784                 if (err)
785                         return err;
786         }
787
788         memset(pages, 0, num_pages * sizeof(struct page *));
789 again:
790         for (i = 0; i < num_pages; i++) {
791                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
792                 if (!pages[i]) {
793                         err = -ENOMEM;
794                         BUG_ON(1);
795                 }
796                 wait_on_page_writeback(pages[i]);
797         }
798         if (start_pos < inode->i_size) {
799                 struct btrfs_ordered_extent *ordered;
800                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
801                                  start_pos, last_pos - 1, 0, &cached_state,
802                                  GFP_NOFS);
803                 ordered = btrfs_lookup_first_ordered_extent(inode,
804                                                             last_pos - 1);
805                 if (ordered &&
806                     ordered->file_offset + ordered->len > start_pos &&
807                     ordered->file_offset < last_pos) {
808                         btrfs_put_ordered_extent(ordered);
809                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
810                                              start_pos, last_pos - 1,
811                                              &cached_state, GFP_NOFS);
812                         for (i = 0; i < num_pages; i++) {
813                                 unlock_page(pages[i]);
814                                 page_cache_release(pages[i]);
815                         }
816                         btrfs_wait_ordered_range(inode, start_pos,
817                                                  last_pos - start_pos);
818                         goto again;
819                 }
820                 if (ordered)
821                         btrfs_put_ordered_extent(ordered);
822
823                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
824                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
825                                   EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
826                                   GFP_NOFS);
827                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
828                                      start_pos, last_pos - 1, &cached_state,
829                                      GFP_NOFS);
830         }
831         for (i = 0; i < num_pages; i++) {
832                 clear_page_dirty_for_io(pages[i]);
833                 set_page_extent_mapped(pages[i]);
834                 WARN_ON(!PageLocked(pages[i]));
835         }
836         return 0;
837 }
838
839 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
840                                     const struct iovec *iov,
841                                     unsigned long nr_segs, loff_t pos)
842 {
843         struct file *file = iocb->ki_filp;
844         struct inode *inode = fdentry(file)->d_inode;
845         struct btrfs_root *root = BTRFS_I(inode)->root;
846         struct page *pinned[2];
847         struct page **pages = NULL;
848         struct iov_iter i;
849         loff_t *ppos = &iocb->ki_pos;
850         loff_t start_pos;
851         ssize_t num_written = 0;
852         ssize_t err = 0;
853         size_t count;
854         size_t ocount;
855         int ret = 0;
856         int nrptrs;
857         unsigned long first_index;
858         unsigned long last_index;
859         int will_write;
860         int buffered = 0;
861         int copied = 0;
862         int dirty_pages = 0;
863
864         will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) ||
865                       (file->f_flags & O_DIRECT));
866
867         pinned[0] = NULL;
868         pinned[1] = NULL;
869
870         start_pos = pos;
871
872         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
873
874         mutex_lock(&inode->i_mutex);
875
876         err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
877         if (err)
878                 goto out;
879         count = ocount;
880
881         current->backing_dev_info = inode->i_mapping->backing_dev_info;
882         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
883         if (err)
884                 goto out;
885
886         if (count == 0)
887                 goto out;
888
889         err = file_remove_suid(file);
890         if (err)
891                 goto out;
892
893         file_update_time(file);
894         BTRFS_I(inode)->sequence++;
895
896         if (unlikely(file->f_flags & O_DIRECT)) {
897                 num_written = generic_file_direct_write(iocb, iov, &nr_segs,
898                                                         pos, ppos, count,
899                                                         ocount);
900                 /*
901                  * the generic O_DIRECT will update in-memory i_size after the
902                  * DIOs are done.  But our endio handlers that update the on
903                  * disk i_size never update past the in memory i_size.  So we
904                  * need one more update here to catch any additions to the
905                  * file
906                  */
907                 if (inode->i_size != BTRFS_I(inode)->disk_i_size) {
908                         btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
909                         mark_inode_dirty(inode);
910                 }
911
912                 if (num_written < 0) {
913                         ret = num_written;
914                         num_written = 0;
915                         goto out;
916                 } else if (num_written == count) {
917                         /* pick up pos changes done by the generic code */
918                         pos = *ppos;
919                         goto out;
920                 }
921                 /*
922                  * We are going to do buffered for the rest of the range, so we
923                  * need to make sure to invalidate the buffered pages when we're
924                  * done.
925                  */
926                 buffered = 1;
927                 pos += num_written;
928         }
929
930         iov_iter_init(&i, iov, nr_segs, count, num_written);
931         nrptrs = min((iov_iter_count(&i) + PAGE_CACHE_SIZE - 1) /
932                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
933                      (sizeof(struct page *)));
934         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
935
936         /* generic_write_checks can change our pos */
937         start_pos = pos;
938
939         first_index = pos >> PAGE_CACHE_SHIFT;
940         last_index = (pos + iov_iter_count(&i)) >> PAGE_CACHE_SHIFT;
941
942         /*
943          * there are lots of better ways to do this, but this code
944          * makes sure the first and last page in the file range are
945          * up to date and ready for cow
946          */
947         if ((pos & (PAGE_CACHE_SIZE - 1))) {
948                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
949                 if (!PageUptodate(pinned[0])) {
950                         ret = btrfs_readpage(NULL, pinned[0]);
951                         BUG_ON(ret);
952                         wait_on_page_locked(pinned[0]);
953                 } else {
954                         unlock_page(pinned[0]);
955                 }
956         }
957         if ((pos + iov_iter_count(&i)) & (PAGE_CACHE_SIZE - 1)) {
958                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
959                 if (!PageUptodate(pinned[1])) {
960                         ret = btrfs_readpage(NULL, pinned[1]);
961                         BUG_ON(ret);
962                         wait_on_page_locked(pinned[1]);
963                 } else {
964                         unlock_page(pinned[1]);
965                 }
966         }
967
968         while (iov_iter_count(&i) > 0) {
969                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
970                 size_t write_bytes = min(iov_iter_count(&i),
971                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
972                                          offset);
973                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
974                                         PAGE_CACHE_SHIFT;
975
976                 WARN_ON(num_pages > nrptrs);
977                 memset(pages, 0, sizeof(struct page *) * nrptrs);
978
979                 /*
980                  * Fault pages before locking them in prepare_pages
981                  * to avoid recursive lock
982                  */
983                 if (unlikely(iov_iter_fault_in_readable(&i, write_bytes))) {
984                         ret = -EFAULT;
985                         goto out;
986                 }
987
988                 ret = btrfs_delalloc_reserve_space(inode,
989                                         num_pages << PAGE_CACHE_SHIFT);
990                 if (ret)
991                         goto out;
992
993                 ret = prepare_pages(root, file, pages, num_pages,
994                                     pos, first_index, last_index,
995                                     write_bytes);
996                 if (ret) {
997                         btrfs_delalloc_release_space(inode,
998                                         num_pages << PAGE_CACHE_SHIFT);
999                         goto out;
1000                 }
1001
1002                 copied = btrfs_copy_from_user(pos, num_pages,
1003                                            write_bytes, pages, &i);
1004                 dirty_pages = (copied + PAGE_CACHE_SIZE - 1) >>
1005                                         PAGE_CACHE_SHIFT;
1006
1007                 if (num_pages > dirty_pages) {
1008                         if (copied > 0)
1009                                 atomic_inc(
1010                                         &BTRFS_I(inode)->outstanding_extents);
1011                         btrfs_delalloc_release_space(inode,
1012                                         (num_pages - dirty_pages) <<
1013                                         PAGE_CACHE_SHIFT);
1014                 }
1015
1016                 if (copied > 0) {
1017                         dirty_and_release_pages(NULL, root, file, pages,
1018                                                 dirty_pages, pos, copied);
1019                 }
1020
1021                 btrfs_drop_pages(pages, num_pages);
1022
1023                 if (copied > 0) {
1024                         if (will_write) {
1025                                 filemap_fdatawrite_range(inode->i_mapping, pos,
1026                                                          pos + copied - 1);
1027                         } else {
1028                                 balance_dirty_pages_ratelimited_nr(
1029                                                         inode->i_mapping,
1030                                                         dirty_pages);
1031                                 if (dirty_pages <
1032                                 (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1033                                         btrfs_btree_balance_dirty(root, 1);
1034                                 btrfs_throttle(root);
1035                         }
1036                 }
1037
1038                 pos += copied;
1039                 num_written += copied;
1040
1041                 cond_resched();
1042         }
1043 out:
1044         mutex_unlock(&inode->i_mutex);
1045         if (ret)
1046                 err = ret;
1047
1048         kfree(pages);
1049         if (pinned[0])
1050                 page_cache_release(pinned[0]);
1051         if (pinned[1])
1052                 page_cache_release(pinned[1]);
1053         *ppos = pos;
1054
1055         /*
1056          * we want to make sure fsync finds this change
1057          * but we haven't joined a transaction running right now.
1058          *
1059          * Later on, someone is sure to update the inode and get the
1060          * real transid recorded.
1061          *
1062          * We set last_trans now to the fs_info generation + 1,
1063          * this will either be one more than the running transaction
1064          * or the generation used for the next transaction if there isn't
1065          * one running right now.
1066          */
1067         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1068
1069         if (num_written > 0 && will_write) {
1070                 struct btrfs_trans_handle *trans;
1071
1072                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1073                 if (err)
1074                         num_written = err;
1075
1076                 if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
1077                         trans = btrfs_start_transaction(root, 0);
1078                         if (IS_ERR(trans)) {
1079                                 num_written = PTR_ERR(trans);
1080                                 goto done;
1081                         }
1082                         mutex_lock(&inode->i_mutex);
1083                         ret = btrfs_log_dentry_safe(trans, root,
1084                                                     file->f_dentry);
1085                         mutex_unlock(&inode->i_mutex);
1086                         if (ret == 0) {
1087                                 ret = btrfs_sync_log(trans, root);
1088                                 if (ret == 0)
1089                                         btrfs_end_transaction(trans, root);
1090                                 else
1091                                         btrfs_commit_transaction(trans, root);
1092                         } else if (ret != BTRFS_NO_LOG_SYNC) {
1093                                 btrfs_commit_transaction(trans, root);
1094                         } else {
1095                                 btrfs_end_transaction(trans, root);
1096                         }
1097                 }
1098                 if (file->f_flags & O_DIRECT && buffered) {
1099                         invalidate_mapping_pages(inode->i_mapping,
1100                               start_pos >> PAGE_CACHE_SHIFT,
1101                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1102                 }
1103         }
1104 done:
1105         current->backing_dev_info = NULL;
1106         return num_written ? num_written : err;
1107 }
1108
1109 int btrfs_release_file(struct inode *inode, struct file *filp)
1110 {
1111         /*
1112          * ordered_data_close is set by settattr when we are about to truncate
1113          * a file from a non-zero size to a zero size.  This tries to
1114          * flush down new bytes that may have been written if the
1115          * application were using truncate to replace a file in place.
1116          */
1117         if (BTRFS_I(inode)->ordered_data_close) {
1118                 BTRFS_I(inode)->ordered_data_close = 0;
1119                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1120                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1121                         filemap_flush(inode->i_mapping);
1122         }
1123         if (filp->private_data)
1124                 btrfs_ioctl_trans_end(filp);
1125         return 0;
1126 }
1127
1128 /*
1129  * fsync call for both files and directories.  This logs the inode into
1130  * the tree log instead of forcing full commits whenever possible.
1131  *
1132  * It needs to call filemap_fdatawait so that all ordered extent updates are
1133  * in the metadata btree are up to date for copying to the log.
1134  *
1135  * It drops the inode mutex before doing the tree log commit.  This is an
1136  * important optimization for directories because holding the mutex prevents
1137  * new operations on the dir while we write to disk.
1138  */
1139 int btrfs_sync_file(struct file *file, int datasync)
1140 {
1141         struct dentry *dentry = file->f_path.dentry;
1142         struct inode *inode = dentry->d_inode;
1143         struct btrfs_root *root = BTRFS_I(inode)->root;
1144         int ret = 0;
1145         struct btrfs_trans_handle *trans;
1146
1147
1148         /* we wait first, since the writeback may change the inode */
1149         root->log_batch++;
1150         /* the VFS called filemap_fdatawrite for us */
1151         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1152         root->log_batch++;
1153
1154         /*
1155          * check the transaction that last modified this inode
1156          * and see if its already been committed
1157          */
1158         if (!BTRFS_I(inode)->last_trans)
1159                 goto out;
1160
1161         /*
1162          * if the last transaction that changed this file was before
1163          * the current transaction, we can bail out now without any
1164          * syncing
1165          */
1166         mutex_lock(&root->fs_info->trans_mutex);
1167         if (BTRFS_I(inode)->last_trans <=
1168             root->fs_info->last_trans_committed) {
1169                 BTRFS_I(inode)->last_trans = 0;
1170                 mutex_unlock(&root->fs_info->trans_mutex);
1171                 goto out;
1172         }
1173         mutex_unlock(&root->fs_info->trans_mutex);
1174
1175         /*
1176          * ok we haven't committed the transaction yet, lets do a commit
1177          */
1178         if (file->private_data)
1179                 btrfs_ioctl_trans_end(file);
1180
1181         trans = btrfs_start_transaction(root, 0);
1182         if (IS_ERR(trans)) {
1183                 ret = PTR_ERR(trans);
1184                 goto out;
1185         }
1186
1187         ret = btrfs_log_dentry_safe(trans, root, dentry);
1188         if (ret < 0)
1189                 goto out;
1190
1191         /* we've logged all the items and now have a consistent
1192          * version of the file in the log.  It is possible that
1193          * someone will come in and modify the file, but that's
1194          * fine because the log is consistent on disk, and we
1195          * have references to all of the file's extents
1196          *
1197          * It is possible that someone will come in and log the
1198          * file again, but that will end up using the synchronization
1199          * inside btrfs_sync_log to keep things safe.
1200          */
1201         mutex_unlock(&dentry->d_inode->i_mutex);
1202
1203         if (ret != BTRFS_NO_LOG_SYNC) {
1204                 if (ret > 0) {
1205                         ret = btrfs_commit_transaction(trans, root);
1206                 } else {
1207                         ret = btrfs_sync_log(trans, root);
1208                         if (ret == 0)
1209                                 ret = btrfs_end_transaction(trans, root);
1210                         else
1211                                 ret = btrfs_commit_transaction(trans, root);
1212                 }
1213         } else {
1214                 ret = btrfs_end_transaction(trans, root);
1215         }
1216         mutex_lock(&dentry->d_inode->i_mutex);
1217 out:
1218         return ret > 0 ? -EIO : ret;
1219 }
1220
1221 static const struct vm_operations_struct btrfs_file_vm_ops = {
1222         .fault          = filemap_fault,
1223         .page_mkwrite   = btrfs_page_mkwrite,
1224 };
1225
1226 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1227 {
1228         struct address_space *mapping = filp->f_mapping;
1229
1230         if (!mapping->a_ops->readpage)
1231                 return -ENOEXEC;
1232
1233         file_accessed(filp);
1234         vma->vm_ops = &btrfs_file_vm_ops;
1235         vma->vm_flags |= VM_CAN_NONLINEAR;
1236
1237         return 0;
1238 }
1239
1240 const struct file_operations btrfs_file_operations = {
1241         .llseek         = generic_file_llseek,
1242         .read           = do_sync_read,
1243         .write          = do_sync_write,
1244         .aio_read       = generic_file_aio_read,
1245         .splice_read    = generic_file_splice_read,
1246         .aio_write      = btrfs_file_aio_write,
1247         .mmap           = btrfs_file_mmap,
1248         .open           = generic_file_open,
1249         .release        = btrfs_release_file,
1250         .fsync          = btrfs_sync_file,
1251         .unlocked_ioctl = btrfs_ioctl,
1252 #ifdef CONFIG_COMPAT
1253         .compat_ioctl   = btrfs_ioctl,
1254 #endif
1255 };