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TOMOYO Linux Cross Reference
Linux/fs/btrfs/ordered-data.c

Version: ~ [ linux-5.2 ] ~ [ linux-5.1.16 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.57 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.132 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.184 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.184 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.69 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  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/slab.h>
 20 #include <linux/blkdev.h>
 21 #include <linux/writeback.h>
 22 #include <linux/pagevec.h>
 23 #include "ctree.h"
 24 #include "transaction.h"
 25 #include "btrfs_inode.h"
 26 #include "extent_io.h"
 27 
 28 static u64 entry_end(struct btrfs_ordered_extent *entry)
 29 {
 30         if (entry->file_offset + entry->len < entry->file_offset)
 31                 return (u64)-1;
 32         return entry->file_offset + entry->len;
 33 }
 34 
 35 /* returns NULL if the insertion worked, or it returns the node it did find
 36  * in the tree
 37  */
 38 static struct rb_node *tree_insert(struct rb_root *root, u64 file_offset,
 39                                    struct rb_node *node)
 40 {
 41         struct rb_node **p = &root->rb_node;
 42         struct rb_node *parent = NULL;
 43         struct btrfs_ordered_extent *entry;
 44 
 45         while (*p) {
 46                 parent = *p;
 47                 entry = rb_entry(parent, struct btrfs_ordered_extent, rb_node);
 48 
 49                 if (file_offset < entry->file_offset)
 50                         p = &(*p)->rb_left;
 51                 else if (file_offset >= entry_end(entry))
 52                         p = &(*p)->rb_right;
 53                 else
 54                         return parent;
 55         }
 56 
 57         rb_link_node(node, parent, p);
 58         rb_insert_color(node, root);
 59         return NULL;
 60 }
 61 
 62 /*
 63  * look for a given offset in the tree, and if it can't be found return the
 64  * first lesser offset
 65  */
 66 static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset,
 67                                      struct rb_node **prev_ret)
 68 {
 69         struct rb_node *n = root->rb_node;
 70         struct rb_node *prev = NULL;
 71         struct rb_node *test;
 72         struct btrfs_ordered_extent *entry;
 73         struct btrfs_ordered_extent *prev_entry = NULL;
 74 
 75         while (n) {
 76                 entry = rb_entry(n, struct btrfs_ordered_extent, rb_node);
 77                 prev = n;
 78                 prev_entry = entry;
 79 
 80                 if (file_offset < entry->file_offset)
 81                         n = n->rb_left;
 82                 else if (file_offset >= entry_end(entry))
 83                         n = n->rb_right;
 84                 else
 85                         return n;
 86         }
 87         if (!prev_ret)
 88                 return NULL;
 89 
 90         while (prev && file_offset >= entry_end(prev_entry)) {
 91                 test = rb_next(prev);
 92                 if (!test)
 93                         break;
 94                 prev_entry = rb_entry(test, struct btrfs_ordered_extent,
 95                                       rb_node);
 96                 if (file_offset < entry_end(prev_entry))
 97                         break;
 98 
 99                 prev = test;
100         }
101         if (prev)
102                 prev_entry = rb_entry(prev, struct btrfs_ordered_extent,
103                                       rb_node);
104         while (prev && file_offset < entry_end(prev_entry)) {
105                 test = rb_prev(prev);
106                 if (!test)
107                         break;
108                 prev_entry = rb_entry(test, struct btrfs_ordered_extent,
109                                       rb_node);
110                 prev = test;
111         }
112         *prev_ret = prev;
113         return NULL;
114 }
115 
116 /*
117  * helper to check if a given offset is inside a given entry
118  */
119 static int offset_in_entry(struct btrfs_ordered_extent *entry, u64 file_offset)
120 {
121         if (file_offset < entry->file_offset ||
122             entry->file_offset + entry->len <= file_offset)
123                 return 0;
124         return 1;
125 }
126 
127 static int range_overlaps(struct btrfs_ordered_extent *entry, u64 file_offset,
128                           u64 len)
129 {
130         if (file_offset + len <= entry->file_offset ||
131             entry->file_offset + entry->len <= file_offset)
132                 return 0;
133         return 1;
134 }
135 
136 /*
137  * look find the first ordered struct that has this offset, otherwise
138  * the first one less than this offset
139  */
140 static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
141                                           u64 file_offset)
142 {
143         struct rb_root *root = &tree->tree;
144         struct rb_node *prev = NULL;
145         struct rb_node *ret;
146         struct btrfs_ordered_extent *entry;
147 
148         if (tree->last) {
149                 entry = rb_entry(tree->last, struct btrfs_ordered_extent,
150                                  rb_node);
151                 if (offset_in_entry(entry, file_offset))
152                         return tree->last;
153         }
154         ret = __tree_search(root, file_offset, &prev);
155         if (!ret)
156                 ret = prev;
157         if (ret)
158                 tree->last = ret;
159         return ret;
160 }
161 
162 /* allocate and add a new ordered_extent into the per-inode tree.
163  * file_offset is the logical offset in the file
164  *
165  * start is the disk block number of an extent already reserved in the
166  * extent allocation tree
167  *
168  * len is the length of the extent
169  *
170  * The tree is given a single reference on the ordered extent that was
171  * inserted.
172  */
173 static int __btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
174                                       u64 start, u64 len, u64 disk_len,
175                                       int type, int dio, int compress_type)
176 {
177         struct btrfs_ordered_inode_tree *tree;
178         struct rb_node *node;
179         struct btrfs_ordered_extent *entry;
180 
181         tree = &BTRFS_I(inode)->ordered_tree;
182         entry = kzalloc(sizeof(*entry), GFP_NOFS);
183         if (!entry)
184                 return -ENOMEM;
185 
186         entry->file_offset = file_offset;
187         entry->start = start;
188         entry->len = len;
189         entry->disk_len = disk_len;
190         entry->bytes_left = len;
191         entry->inode = inode;
192         entry->compress_type = compress_type;
193         if (type != BTRFS_ORDERED_IO_DONE && type != BTRFS_ORDERED_COMPLETE)
194                 set_bit(type, &entry->flags);
195 
196         if (dio)
197                 set_bit(BTRFS_ORDERED_DIRECT, &entry->flags);
198 
199         /* one ref for the tree */
200         atomic_set(&entry->refs, 1);
201         init_waitqueue_head(&entry->wait);
202         INIT_LIST_HEAD(&entry->list);
203         INIT_LIST_HEAD(&entry->root_extent_list);
204 
205         trace_btrfs_ordered_extent_add(inode, entry);
206 
207         spin_lock(&tree->lock);
208         node = tree_insert(&tree->tree, file_offset,
209                            &entry->rb_node);
210         BUG_ON(node);
211         spin_unlock(&tree->lock);
212 
213         spin_lock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
214         list_add_tail(&entry->root_extent_list,
215                       &BTRFS_I(inode)->root->fs_info->ordered_extents);
216         spin_unlock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
217 
218         BUG_ON(node);
219         return 0;
220 }
221 
222 int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
223                              u64 start, u64 len, u64 disk_len, int type)
224 {
225         return __btrfs_add_ordered_extent(inode, file_offset, start, len,
226                                           disk_len, type, 0,
227                                           BTRFS_COMPRESS_NONE);
228 }
229 
230 int btrfs_add_ordered_extent_dio(struct inode *inode, u64 file_offset,
231                                  u64 start, u64 len, u64 disk_len, int type)
232 {
233         return __btrfs_add_ordered_extent(inode, file_offset, start, len,
234                                           disk_len, type, 1,
235                                           BTRFS_COMPRESS_NONE);
236 }
237 
238 int btrfs_add_ordered_extent_compress(struct inode *inode, u64 file_offset,
239                                       u64 start, u64 len, u64 disk_len,
240                                       int type, int compress_type)
241 {
242         return __btrfs_add_ordered_extent(inode, file_offset, start, len,
243                                           disk_len, type, 0,
244                                           compress_type);
245 }
246 
247 /*
248  * Add a struct btrfs_ordered_sum into the list of checksums to be inserted
249  * when an ordered extent is finished.  If the list covers more than one
250  * ordered extent, it is split across multiples.
251  */
252 int btrfs_add_ordered_sum(struct inode *inode,
253                           struct btrfs_ordered_extent *entry,
254                           struct btrfs_ordered_sum *sum)
255 {
256         struct btrfs_ordered_inode_tree *tree;
257 
258         tree = &BTRFS_I(inode)->ordered_tree;
259         spin_lock(&tree->lock);
260         list_add_tail(&sum->list, &entry->list);
261         spin_unlock(&tree->lock);
262         return 0;
263 }
264 
265 /*
266  * this is used to account for finished IO across a given range
267  * of the file.  The IO may span ordered extents.  If
268  * a given ordered_extent is completely done, 1 is returned, otherwise
269  * 0.
270  *
271  * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used
272  * to make sure this function only returns 1 once for a given ordered extent.
273  *
274  * file_offset is updated to one byte past the range that is recorded as
275  * complete.  This allows you to walk forward in the file.
276  */
277 int btrfs_dec_test_first_ordered_pending(struct inode *inode,
278                                    struct btrfs_ordered_extent **cached,
279                                    u64 *file_offset, u64 io_size)
280 {
281         struct btrfs_ordered_inode_tree *tree;
282         struct rb_node *node;
283         struct btrfs_ordered_extent *entry = NULL;
284         int ret;
285         u64 dec_end;
286         u64 dec_start;
287         u64 to_dec;
288 
289         tree = &BTRFS_I(inode)->ordered_tree;
290         spin_lock(&tree->lock);
291         node = tree_search(tree, *file_offset);
292         if (!node) {
293                 ret = 1;
294                 goto out;
295         }
296 
297         entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
298         if (!offset_in_entry(entry, *file_offset)) {
299                 ret = 1;
300                 goto out;
301         }
302 
303         dec_start = max(*file_offset, entry->file_offset);
304         dec_end = min(*file_offset + io_size, entry->file_offset +
305                       entry->len);
306         *file_offset = dec_end;
307         if (dec_start > dec_end) {
308                 printk(KERN_CRIT "bad ordering dec_start %llu end %llu\n",
309                        (unsigned long long)dec_start,
310                        (unsigned long long)dec_end);
311         }
312         to_dec = dec_end - dec_start;
313         if (to_dec > entry->bytes_left) {
314                 printk(KERN_CRIT "bad ordered accounting left %llu size %llu\n",
315                        (unsigned long long)entry->bytes_left,
316                        (unsigned long long)to_dec);
317         }
318         entry->bytes_left -= to_dec;
319         if (entry->bytes_left == 0)
320                 ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
321         else
322                 ret = 1;
323 out:
324         if (!ret && cached && entry) {
325                 *cached = entry;
326                 atomic_inc(&entry->refs);
327         }
328         spin_unlock(&tree->lock);
329         return ret == 0;
330 }
331 
332 /*
333  * this is used to account for finished IO across a given range
334  * of the file.  The IO should not span ordered extents.  If
335  * a given ordered_extent is completely done, 1 is returned, otherwise
336  * 0.
337  *
338  * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used
339  * to make sure this function only returns 1 once for a given ordered extent.
340  */
341 int btrfs_dec_test_ordered_pending(struct inode *inode,
342                                    struct btrfs_ordered_extent **cached,
343                                    u64 file_offset, u64 io_size)
344 {
345         struct btrfs_ordered_inode_tree *tree;
346         struct rb_node *node;
347         struct btrfs_ordered_extent *entry = NULL;
348         int ret;
349 
350         tree = &BTRFS_I(inode)->ordered_tree;
351         spin_lock(&tree->lock);
352         node = tree_search(tree, file_offset);
353         if (!node) {
354                 ret = 1;
355                 goto out;
356         }
357 
358         entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
359         if (!offset_in_entry(entry, file_offset)) {
360                 ret = 1;
361                 goto out;
362         }
363 
364         if (io_size > entry->bytes_left) {
365                 printk(KERN_CRIT "bad ordered accounting left %llu size %llu\n",
366                        (unsigned long long)entry->bytes_left,
367                        (unsigned long long)io_size);
368         }
369         entry->bytes_left -= io_size;
370         if (entry->bytes_left == 0)
371                 ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
372         else
373                 ret = 1;
374 out:
375         if (!ret && cached && entry) {
376                 *cached = entry;
377                 atomic_inc(&entry->refs);
378         }
379         spin_unlock(&tree->lock);
380         return ret == 0;
381 }
382 
383 /*
384  * used to drop a reference on an ordered extent.  This will free
385  * the extent if the last reference is dropped
386  */
387 int btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)
388 {
389         struct list_head *cur;
390         struct btrfs_ordered_sum *sum;
391 
392         trace_btrfs_ordered_extent_put(entry->inode, entry);
393 
394         if (atomic_dec_and_test(&entry->refs)) {
395                 while (!list_empty(&entry->list)) {
396                         cur = entry->list.next;
397                         sum = list_entry(cur, struct btrfs_ordered_sum, list);
398                         list_del(&sum->list);
399                         kfree(sum);
400                 }
401                 kfree(entry);
402         }
403         return 0;
404 }
405 
406 /*
407  * remove an ordered extent from the tree.  No references are dropped
408  * and you must wake_up entry->wait.  You must hold the tree lock
409  * while you call this function.
410  */
411 static int __btrfs_remove_ordered_extent(struct inode *inode,
412                                 struct btrfs_ordered_extent *entry)
413 {
414         struct btrfs_ordered_inode_tree *tree;
415         struct btrfs_root *root = BTRFS_I(inode)->root;
416         struct rb_node *node;
417 
418         tree = &BTRFS_I(inode)->ordered_tree;
419         node = &entry->rb_node;
420         rb_erase(node, &tree->tree);
421         tree->last = NULL;
422         set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags);
423 
424         spin_lock(&root->fs_info->ordered_extent_lock);
425         list_del_init(&entry->root_extent_list);
426 
427         trace_btrfs_ordered_extent_remove(inode, entry);
428 
429         /*
430          * we have no more ordered extents for this inode and
431          * no dirty pages.  We can safely remove it from the
432          * list of ordered extents
433          */
434         if (RB_EMPTY_ROOT(&tree->tree) &&
435             !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) {
436                 list_del_init(&BTRFS_I(inode)->ordered_operations);
437         }
438         spin_unlock(&root->fs_info->ordered_extent_lock);
439 
440         return 0;
441 }
442 
443 /*
444  * remove an ordered extent from the tree.  No references are dropped
445  * but any waiters are woken.
446  */
447 int btrfs_remove_ordered_extent(struct inode *inode,
448                                 struct btrfs_ordered_extent *entry)
449 {
450         struct btrfs_ordered_inode_tree *tree;
451         int ret;
452 
453         tree = &BTRFS_I(inode)->ordered_tree;
454         spin_lock(&tree->lock);
455         ret = __btrfs_remove_ordered_extent(inode, entry);
456         spin_unlock(&tree->lock);
457         wake_up(&entry->wait);
458 
459         return ret;
460 }
461 
462 /*
463  * wait for all the ordered extents in a root.  This is done when balancing
464  * space between drives.
465  */
466 int btrfs_wait_ordered_extents(struct btrfs_root *root,
467                                int nocow_only, int delay_iput)
468 {
469         struct list_head splice;
470         struct list_head *cur;
471         struct btrfs_ordered_extent *ordered;
472         struct inode *inode;
473 
474         INIT_LIST_HEAD(&splice);
475 
476         spin_lock(&root->fs_info->ordered_extent_lock);
477         list_splice_init(&root->fs_info->ordered_extents, &splice);
478         while (!list_empty(&splice)) {
479                 cur = splice.next;
480                 ordered = list_entry(cur, struct btrfs_ordered_extent,
481                                      root_extent_list);
482                 if (nocow_only &&
483                     !test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags) &&
484                     !test_bit(BTRFS_ORDERED_PREALLOC, &ordered->flags)) {
485                         list_move(&ordered->root_extent_list,
486                                   &root->fs_info->ordered_extents);
487                         cond_resched_lock(&root->fs_info->ordered_extent_lock);
488                         continue;
489                 }
490 
491                 list_del_init(&ordered->root_extent_list);
492                 atomic_inc(&ordered->refs);
493 
494                 /*
495                  * the inode may be getting freed (in sys_unlink path).
496                  */
497                 inode = igrab(ordered->inode);
498 
499                 spin_unlock(&root->fs_info->ordered_extent_lock);
500 
501                 if (inode) {
502                         btrfs_start_ordered_extent(inode, ordered, 1);
503                         btrfs_put_ordered_extent(ordered);
504                         if (delay_iput)
505                                 btrfs_add_delayed_iput(inode);
506                         else
507                                 iput(inode);
508                 } else {
509                         btrfs_put_ordered_extent(ordered);
510                 }
511 
512                 spin_lock(&root->fs_info->ordered_extent_lock);
513         }
514         spin_unlock(&root->fs_info->ordered_extent_lock);
515         return 0;
516 }
517 
518 /*
519  * this is used during transaction commit to write all the inodes
520  * added to the ordered operation list.  These files must be fully on
521  * disk before the transaction commits.
522  *
523  * we have two modes here, one is to just start the IO via filemap_flush
524  * and the other is to wait for all the io.  When we wait, we have an
525  * extra check to make sure the ordered operation list really is empty
526  * before we return
527  */
528 int btrfs_run_ordered_operations(struct btrfs_root *root, int wait)
529 {
530         struct btrfs_inode *btrfs_inode;
531         struct inode *inode;
532         struct list_head splice;
533 
534         INIT_LIST_HEAD(&splice);
535 
536         mutex_lock(&root->fs_info->ordered_operations_mutex);
537         spin_lock(&root->fs_info->ordered_extent_lock);
538 again:
539         list_splice_init(&root->fs_info->ordered_operations, &splice);
540 
541         while (!list_empty(&splice)) {
542                 btrfs_inode = list_entry(splice.next, struct btrfs_inode,
543                                    ordered_operations);
544 
545                 inode = &btrfs_inode->vfs_inode;
546 
547                 list_del_init(&btrfs_inode->ordered_operations);
548 
549                 /*
550                  * the inode may be getting freed (in sys_unlink path).
551                  */
552                 inode = igrab(inode);
553 
554                 if (!wait && inode) {
555                         list_add_tail(&BTRFS_I(inode)->ordered_operations,
556                               &root->fs_info->ordered_operations);
557                 }
558                 spin_unlock(&root->fs_info->ordered_extent_lock);
559 
560                 if (inode) {
561                         if (wait)
562                                 btrfs_wait_ordered_range(inode, 0, (u64)-1);
563                         else
564                                 filemap_flush(inode->i_mapping);
565                         btrfs_add_delayed_iput(inode);
566                 }
567 
568                 cond_resched();
569                 spin_lock(&root->fs_info->ordered_extent_lock);
570         }
571         if (wait && !list_empty(&root->fs_info->ordered_operations))
572                 goto again;
573 
574         spin_unlock(&root->fs_info->ordered_extent_lock);
575         mutex_unlock(&root->fs_info->ordered_operations_mutex);
576 
577         return 0;
578 }
579 
580 /*
581  * Used to start IO or wait for a given ordered extent to finish.
582  *
583  * If wait is one, this effectively waits on page writeback for all the pages
584  * in the extent, and it waits on the io completion code to insert
585  * metadata into the btree corresponding to the extent
586  */
587 void btrfs_start_ordered_extent(struct inode *inode,
588                                        struct btrfs_ordered_extent *entry,
589                                        int wait)
590 {
591         u64 start = entry->file_offset;
592         u64 end = start + entry->len - 1;
593 
594         trace_btrfs_ordered_extent_start(inode, entry);
595 
596         /*
597          * pages in the range can be dirty, clean or writeback.  We
598          * start IO on any dirty ones so the wait doesn't stall waiting
599          * for pdflush to find them
600          */
601         if (!test_bit(BTRFS_ORDERED_DIRECT, &entry->flags))
602                 filemap_fdatawrite_range(inode->i_mapping, start, end);
603         if (wait) {
604                 wait_event(entry->wait, test_bit(BTRFS_ORDERED_COMPLETE,
605                                                  &entry->flags));
606         }
607 }
608 
609 /*
610  * Used to wait on ordered extents across a large range of bytes.
611  */
612 int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
613 {
614         u64 end;
615         u64 orig_end;
616         struct btrfs_ordered_extent *ordered;
617         int found;
618 
619         if (start + len < start) {
620                 orig_end = INT_LIMIT(loff_t);
621         } else {
622                 orig_end = start + len - 1;
623                 if (orig_end > INT_LIMIT(loff_t))
624                         orig_end = INT_LIMIT(loff_t);
625         }
626 again:
627         /* start IO across the range first to instantiate any delalloc
628          * extents
629          */
630         filemap_fdatawrite_range(inode->i_mapping, start, orig_end);
631 
632         /* The compression code will leave pages locked but return from
633          * writepage without setting the page writeback.  Starting again
634          * with WB_SYNC_ALL will end up waiting for the IO to actually start.
635          */
636         filemap_fdatawrite_range(inode->i_mapping, start, orig_end);
637 
638         filemap_fdatawait_range(inode->i_mapping, start, orig_end);
639 
640         end = orig_end;
641         found = 0;
642         while (1) {
643                 ordered = btrfs_lookup_first_ordered_extent(inode, end);
644                 if (!ordered)
645                         break;
646                 if (ordered->file_offset > orig_end) {
647                         btrfs_put_ordered_extent(ordered);
648                         break;
649                 }
650                 if (ordered->file_offset + ordered->len < start) {
651                         btrfs_put_ordered_extent(ordered);
652                         break;
653                 }
654                 found++;
655                 btrfs_start_ordered_extent(inode, ordered, 1);
656                 end = ordered->file_offset;
657                 btrfs_put_ordered_extent(ordered);
658                 if (end == 0 || end == start)
659                         break;
660                 end--;
661         }
662         if (found || test_range_bit(&BTRFS_I(inode)->io_tree, start, orig_end,
663                            EXTENT_DELALLOC, 0, NULL)) {
664                 schedule_timeout(1);
665                 goto again;
666         }
667         return 0;
668 }
669 
670 /*
671  * find an ordered extent corresponding to file_offset.  return NULL if
672  * nothing is found, otherwise take a reference on the extent and return it
673  */
674 struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,
675                                                          u64 file_offset)
676 {
677         struct btrfs_ordered_inode_tree *tree;
678         struct rb_node *node;
679         struct btrfs_ordered_extent *entry = NULL;
680 
681         tree = &BTRFS_I(inode)->ordered_tree;
682         spin_lock(&tree->lock);
683         node = tree_search(tree, file_offset);
684         if (!node)
685                 goto out;
686 
687         entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
688         if (!offset_in_entry(entry, file_offset))
689                 entry = NULL;
690         if (entry)
691                 atomic_inc(&entry->refs);
692 out:
693         spin_unlock(&tree->lock);
694         return entry;
695 }
696 
697 /* Since the DIO code tries to lock a wide area we need to look for any ordered
698  * extents that exist in the range, rather than just the start of the range.
699  */
700 struct btrfs_ordered_extent *btrfs_lookup_ordered_range(struct inode *inode,
701                                                         u64 file_offset,
702                                                         u64 len)
703 {
704         struct btrfs_ordered_inode_tree *tree;
705         struct rb_node *node;
706         struct btrfs_ordered_extent *entry = NULL;
707 
708         tree = &BTRFS_I(inode)->ordered_tree;
709         spin_lock(&tree->lock);
710         node = tree_search(tree, file_offset);
711         if (!node) {
712                 node = tree_search(tree, file_offset + len);
713                 if (!node)
714                         goto out;
715         }
716 
717         while (1) {
718                 entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
719                 if (range_overlaps(entry, file_offset, len))
720                         break;
721 
722                 if (entry->file_offset >= file_offset + len) {
723                         entry = NULL;
724                         break;
725                 }
726                 entry = NULL;
727                 node = rb_next(node);
728                 if (!node)
729                         break;
730         }
731 out:
732         if (entry)
733                 atomic_inc(&entry->refs);
734         spin_unlock(&tree->lock);
735         return entry;
736 }
737 
738 /*
739  * lookup and return any extent before 'file_offset'.  NULL is returned
740  * if none is found
741  */
742 struct btrfs_ordered_extent *
743 btrfs_lookup_first_ordered_extent(struct inode *inode, u64 file_offset)
744 {
745         struct btrfs_ordered_inode_tree *tree;
746         struct rb_node *node;
747         struct btrfs_ordered_extent *entry = NULL;
748 
749         tree = &BTRFS_I(inode)->ordered_tree;
750         spin_lock(&tree->lock);
751         node = tree_search(tree, file_offset);
752         if (!node)
753                 goto out;
754 
755         entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
756         atomic_inc(&entry->refs);
757 out:
758         spin_unlock(&tree->lock);
759         return entry;
760 }
761 
762 /*
763  * After an extent is done, call this to conditionally update the on disk
764  * i_size.  i_size is updated to cover any fully written part of the file.
765  */
766 int btrfs_ordered_update_i_size(struct inode *inode, u64 offset,
767                                 struct btrfs_ordered_extent *ordered)
768 {
769         struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
770         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
771         u64 disk_i_size;
772         u64 new_i_size;
773         u64 i_size_test;
774         u64 i_size = i_size_read(inode);
775         struct rb_node *node;
776         struct rb_node *prev = NULL;
777         struct btrfs_ordered_extent *test;
778         int ret = 1;
779 
780         if (ordered)
781                 offset = entry_end(ordered);
782         else
783                 offset = ALIGN(offset, BTRFS_I(inode)->root->sectorsize);
784 
785         spin_lock(&tree->lock);
786         disk_i_size = BTRFS_I(inode)->disk_i_size;
787 
788         /* truncate file */
789         if (disk_i_size > i_size) {
790                 BTRFS_I(inode)->disk_i_size = i_size;
791                 ret = 0;
792                 goto out;
793         }
794 
795         /*
796          * if the disk i_size is already at the inode->i_size, or
797          * this ordered extent is inside the disk i_size, we're done
798          */
799         if (disk_i_size == i_size || offset <= disk_i_size) {
800                 goto out;
801         }
802 
803         /*
804          * we can't update the disk_isize if there are delalloc bytes
805          * between disk_i_size and  this ordered extent
806          */
807         if (test_range_bit(io_tree, disk_i_size, offset - 1,
808                            EXTENT_DELALLOC, 0, NULL)) {
809                 goto out;
810         }
811         /*
812          * walk backward from this ordered extent to disk_i_size.
813          * if we find an ordered extent then we can't update disk i_size
814          * yet
815          */
816         if (ordered) {
817                 node = rb_prev(&ordered->rb_node);
818         } else {
819                 prev = tree_search(tree, offset);
820                 /*
821                  * we insert file extents without involving ordered struct,
822                  * so there should be no ordered struct cover this offset
823                  */
824                 if (prev) {
825                         test = rb_entry(prev, struct btrfs_ordered_extent,
826                                         rb_node);
827                         BUG_ON(offset_in_entry(test, offset));
828                 }
829                 node = prev;
830         }
831         while (node) {
832                 test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
833                 if (test->file_offset + test->len <= disk_i_size)
834                         break;
835                 if (test->file_offset >= i_size)
836                         break;
837                 if (test->file_offset >= disk_i_size)
838                         goto out;
839                 node = rb_prev(node);
840         }
841         new_i_size = min_t(u64, offset, i_size);
842 
843         /*
844          * at this point, we know we can safely update i_size to at least
845          * the offset from this ordered extent.  But, we need to
846          * walk forward and see if ios from higher up in the file have
847          * finished.
848          */
849         if (ordered) {
850                 node = rb_next(&ordered->rb_node);
851         } else {
852                 if (prev)
853                         node = rb_next(prev);
854                 else
855                         node = rb_first(&tree->tree);
856         }
857         i_size_test = 0;
858         if (node) {
859                 /*
860                  * do we have an area where IO might have finished
861                  * between our ordered extent and the next one.
862                  */
863                 test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
864                 if (test->file_offset > offset)
865                         i_size_test = test->file_offset;
866         } else {
867                 i_size_test = i_size;
868         }
869 
870         /*
871          * i_size_test is the end of a region after this ordered
872          * extent where there are no ordered extents.  As long as there
873          * are no delalloc bytes in this area, it is safe to update
874          * disk_i_size to the end of the region.
875          */
876         if (i_size_test > offset &&
877             !test_range_bit(io_tree, offset, i_size_test - 1,
878                             EXTENT_DELALLOC, 0, NULL)) {
879                 new_i_size = min_t(u64, i_size_test, i_size);
880         }
881         BTRFS_I(inode)->disk_i_size = new_i_size;
882         ret = 0;
883 out:
884         /*
885          * we need to remove the ordered extent with the tree lock held
886          * so that other people calling this function don't find our fully
887          * processed ordered entry and skip updating the i_size
888          */
889         if (ordered)
890                 __btrfs_remove_ordered_extent(inode, ordered);
891         spin_unlock(&tree->lock);
892         if (ordered)
893                 wake_up(&ordered->wait);
894         return ret;
895 }
896 
897 /*
898  * search the ordered extents for one corresponding to 'offset' and
899  * try to find a checksum.  This is used because we allow pages to
900  * be reclaimed before their checksum is actually put into the btree
901  */
902 int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr,
903                            u32 *sum)
904 {
905         struct btrfs_ordered_sum *ordered_sum;
906         struct btrfs_sector_sum *sector_sums;
907         struct btrfs_ordered_extent *ordered;
908         struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
909         unsigned long num_sectors;
910         unsigned long i;
911         u32 sectorsize = BTRFS_I(inode)->root->sectorsize;
912         int ret = 1;
913 
914         ordered = btrfs_lookup_ordered_extent(inode, offset);
915         if (!ordered)
916                 return 1;
917 
918         spin_lock(&tree->lock);
919         list_for_each_entry_reverse(ordered_sum, &ordered->list, list) {
920                 if (disk_bytenr >= ordered_sum->bytenr) {
921                         num_sectors = ordered_sum->len / sectorsize;
922                         sector_sums = ordered_sum->sums;
923                         for (i = 0; i < num_sectors; i++) {
924                                 if (sector_sums[i].bytenr == disk_bytenr) {
925                                         *sum = sector_sums[i].sum;
926                                         ret = 0;
927                                         goto out;
928                                 }
929                         }
930                 }
931         }
932 out:
933         spin_unlock(&tree->lock);
934         btrfs_put_ordered_extent(ordered);
935         return ret;
936 }
937 
938 
939 /*
940  * add a given inode to the list of inodes that must be fully on
941  * disk before a transaction commit finishes.
942  *
943  * This basically gives us the ext3 style data=ordered mode, and it is mostly
944  * used to make sure renamed files are fully on disk.
945  *
946  * It is a noop if the inode is already fully on disk.
947  *
948  * If trans is not null, we'll do a friendly check for a transaction that
949  * is already flushing things and force the IO down ourselves.
950  */
951 int btrfs_add_ordered_operation(struct btrfs_trans_handle *trans,
952                                 struct btrfs_root *root,
953                                 struct inode *inode)
954 {
955         u64 last_mod;
956 
957         last_mod = max(BTRFS_I(inode)->generation, BTRFS_I(inode)->last_trans);
958 
959         /*
960          * if this file hasn't been changed since the last transaction
961          * commit, we can safely return without doing anything
962          */
963         if (last_mod < root->fs_info->last_trans_committed)
964                 return 0;
965 
966         /*
967          * the transaction is already committing.  Just start the IO and
968          * don't bother with all of this list nonsense
969          */
970         if (trans && root->fs_info->running_transaction->blocked) {
971                 btrfs_wait_ordered_range(inode, 0, (u64)-1);
972                 return 0;
973         }
974 
975         spin_lock(&root->fs_info->ordered_extent_lock);
976         if (list_empty(&BTRFS_I(inode)->ordered_operations)) {
977                 list_add_tail(&BTRFS_I(inode)->ordered_operations,
978                               &root->fs_info->ordered_operations);
979         }
980         spin_unlock(&root->fs_info->ordered_extent_lock);
981 
982         return 0;
983 }
984 

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