/fs/btrfs/ordered-data.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/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
 28static 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 */
 38static 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 */
 66static 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 */
119static 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
127static 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 */
140static 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 */
173static 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
222int 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
230int 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
238int 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 */
252int 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 */
277int 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;
323out:
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 */
341int 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;
374out:
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 */
387int 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 */
411static 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 */
447int 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 */
466int 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 */
528int 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);
538again:
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 */
587void 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 */
612int 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	}
626again:
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 */
674struct 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);
692out:
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 */
700struct 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	}
731out:
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 */
742struct btrfs_ordered_extent *
743btrfs_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);
757out:
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 */
766int 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;
883out:
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 */
902int 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	}
932out:
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 */
951int 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}