1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <linux/blkdev.h>
  4#include <linux/iversion.h>
  5#include "ctree.h"
  6#include "fs.h"
  7#include "messages.h"
  8#include "compression.h"
 
  9#include "delalloc-space.h"
 10#include "disk-io.h"
 11#include "reflink.h"
 12#include "transaction.h"
 13#include "subpage.h"
 14#include "accessors.h"
 15#include "file-item.h"
 16#include "file.h"
 17#include "super.h"
 18
 19#define BTRFS_MAX_DEDUPE_LEN	SZ_16M
 20
 21static int clone_finish_inode_update(struct btrfs_trans_handle *trans,
 22				     struct inode *inode,
 23				     u64 endoff,
 24				     const u64 destoff,
 25				     const u64 olen,
 26				     int no_time_update)
 27{
 28	struct btrfs_root *root = BTRFS_I(inode)->root;
 29	int ret;
 30
 31	inode_inc_iversion(inode);
 32	if (!no_time_update) {
 33		inode->i_mtime = current_time(inode);
 34		inode->i_ctime = inode->i_mtime;
 35	}
 36	/*
 37	 * We round up to the block size at eof when determining which
 38	 * extents to clone above, but shouldn't round up the file size.
 39	 */
 40	if (endoff > destoff + olen)
 41		endoff = destoff + olen;
 42	if (endoff > inode->i_size) {
 43		i_size_write(inode, endoff);
 44		btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
 45	}
 46
 47	ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
 48	if (ret) {
 49		btrfs_abort_transaction(trans, ret);
 50		btrfs_end_transaction(trans);
 51		goto out;
 52	}
 53	ret = btrfs_end_transaction(trans);
 54out:
 55	return ret;
 56}
 57
 58static int copy_inline_to_page(struct btrfs_inode *inode,
 59			       const u64 file_offset,
 60			       char *inline_data,
 61			       const u64 size,
 62			       const u64 datal,
 63			       const u8 comp_type)
 64{
 65	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 66	const u32 block_size = fs_info->sectorsize;
 67	const u64 range_end = file_offset + block_size - 1;
 68	const size_t inline_size = size - btrfs_file_extent_calc_inline_size(0);
 69	char *data_start = inline_data + btrfs_file_extent_calc_inline_size(0);
 70	struct extent_changeset *data_reserved = NULL;
 71	struct page *page = NULL;
 72	struct address_space *mapping = inode->vfs_inode.i_mapping;
 73	int ret;
 74
 75	ASSERT(IS_ALIGNED(file_offset, block_size));
 76
 77	/*
 78	 * We have flushed and locked the ranges of the source and destination
 79	 * inodes, we also have locked the inodes, so we are safe to do a
 80	 * reservation here. Also we must not do the reservation while holding
 81	 * a transaction open, otherwise we would deadlock.
 82	 */
 83	ret = btrfs_delalloc_reserve_space(inode, &data_reserved, file_offset,
 84					   block_size);
 85	if (ret)
 86		goto out;
 87
 88	page = find_or_create_page(mapping, file_offset >> PAGE_SHIFT,
 89				   btrfs_alloc_write_mask(mapping));
 90	if (!page) {
 91		ret = -ENOMEM;
 92		goto out_unlock;
 93	}
 94
 95	ret = set_page_extent_mapped(page);
 96	if (ret < 0)
 97		goto out_unlock;
 98
 99	clear_extent_bit(&inode->io_tree, file_offset, range_end,
100			 EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
101			 NULL);
102	ret = btrfs_set_extent_delalloc(inode, file_offset, range_end, 0, NULL);
 
103	if (ret)
104		goto out_unlock;
105
106	/*
107	 * After dirtying the page our caller will need to start a transaction,
108	 * and if we are low on metadata free space, that can cause flushing of
109	 * delalloc for all inodes in order to get metadata space released.
110	 * However we are holding the range locked for the whole duration of
111	 * the clone/dedupe operation, so we may deadlock if that happens and no
112	 * other task releases enough space. So mark this inode as not being
113	 * possible to flush to avoid such deadlock. We will clear that flag
114	 * when we finish cloning all extents, since a transaction is started
115	 * after finding each extent to clone.
116	 */
117	set_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &inode->runtime_flags);
118
119	if (comp_type == BTRFS_COMPRESS_NONE) {
120		memcpy_to_page(page, offset_in_page(file_offset), data_start,
121			       datal);
 
 
 
 
122	} else {
123		ret = btrfs_decompress(comp_type, data_start, page,
124				       offset_in_page(file_offset),
125				       inline_size, datal);
126		if (ret)
127			goto out_unlock;
128		flush_dcache_page(page);
129	}
130
131	/*
132	 * If our inline data is smaller then the block/page size, then the
133	 * remaining of the block/page is equivalent to zeroes. We had something
134	 * like the following done:
135	 *
136	 * $ xfs_io -f -c "pwrite -S 0xab 0 500" file
137	 * $ sync  # (or fsync)
138	 * $ xfs_io -c "falloc 0 4K" file
139	 * $ xfs_io -c "pwrite -S 0xcd 4K 4K"
140	 *
141	 * So what's in the range [500, 4095] corresponds to zeroes.
142	 */
143	if (datal < block_size)
144		memzero_page(page, datal, block_size - datal);
 
 
 
 
 
 
145
146	btrfs_page_set_uptodate(fs_info, page, file_offset, block_size);
147	btrfs_page_clear_checked(fs_info, page, file_offset, block_size);
148	btrfs_page_set_dirty(fs_info, page, file_offset, block_size);
149out_unlock:
150	if (page) {
151		unlock_page(page);
152		put_page(page);
153	}
154	if (ret)
155		btrfs_delalloc_release_space(inode, data_reserved, file_offset,
156					     block_size, true);
157	btrfs_delalloc_release_extents(inode, block_size);
158out:
159	extent_changeset_free(data_reserved);
160
161	return ret;
162}
163
164/*
165 * Deal with cloning of inline extents. We try to copy the inline extent from
166 * the source inode to destination inode when possible. When not possible we
167 * copy the inline extent's data into the respective page of the inode.
168 */
169static int clone_copy_inline_extent(struct inode *dst,
170				    struct btrfs_path *path,
171				    struct btrfs_key *new_key,
172				    const u64 drop_start,
173				    const u64 datal,
174				    const u64 size,
175				    const u8 comp_type,
176				    char *inline_data,
177				    struct btrfs_trans_handle **trans_out)
178{
179	struct btrfs_fs_info *fs_info = btrfs_sb(dst->i_sb);
180	struct btrfs_root *root = BTRFS_I(dst)->root;
181	const u64 aligned_end = ALIGN(new_key->offset + datal,
182				      fs_info->sectorsize);
183	struct btrfs_trans_handle *trans = NULL;
184	struct btrfs_drop_extents_args drop_args = { 0 };
185	int ret;
186	struct btrfs_key key;
187
188	if (new_key->offset > 0) {
189		ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
190					  inline_data, size, datal, comp_type);
191		goto out;
192	}
193
194	key.objectid = btrfs_ino(BTRFS_I(dst));
195	key.type = BTRFS_EXTENT_DATA_KEY;
196	key.offset = 0;
197	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
198	if (ret < 0) {
199		return ret;
200	} else if (ret > 0) {
201		if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
202			ret = btrfs_next_leaf(root, path);
203			if (ret < 0)
204				return ret;
205			else if (ret > 0)
206				goto copy_inline_extent;
207		}
208		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
209		if (key.objectid == btrfs_ino(BTRFS_I(dst)) &&
210		    key.type == BTRFS_EXTENT_DATA_KEY) {
211			/*
212			 * There's an implicit hole at file offset 0, copy the
213			 * inline extent's data to the page.
214			 */
215			ASSERT(key.offset > 0);
216			goto copy_to_page;
 
 
 
217		}
218	} else if (i_size_read(dst) <= datal) {
219		struct btrfs_file_extent_item *ei;
220
221		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
222				    struct btrfs_file_extent_item);
223		/*
224		 * If it's an inline extent replace it with the source inline
225		 * extent, otherwise copy the source inline extent data into
226		 * the respective page at the destination inode.
227		 */
228		if (btrfs_file_extent_type(path->nodes[0], ei) ==
229		    BTRFS_FILE_EXTENT_INLINE)
230			goto copy_inline_extent;
231
232		goto copy_to_page;
 
 
233	}
234
235copy_inline_extent:
 
236	/*
237	 * We have no extent items, or we have an extent at offset 0 which may
238	 * or may not be inlined. All these cases are dealt the same way.
239	 */
240	if (i_size_read(dst) > datal) {
241		/*
242		 * At the destination offset 0 we have either a hole, a regular
243		 * extent or an inline extent larger then the one we want to
244		 * clone. Deal with all these cases by copying the inline extent
245		 * data into the respective page at the destination inode.
246		 */
247		goto copy_to_page;
 
 
248	}
249
250	/*
251	 * Release path before starting a new transaction so we don't hold locks
252	 * that would confuse lockdep.
253	 */
254	btrfs_release_path(path);
255	/*
256	 * If we end up here it means were copy the inline extent into a leaf
257	 * of the destination inode. We know we will drop or adjust at most one
258	 * extent item in the destination root.
259	 *
260	 * 1 unit - adjusting old extent (we may have to split it)
261	 * 1 unit - add new extent
262	 * 1 unit - inode update
263	 */
264	trans = btrfs_start_transaction(root, 3);
265	if (IS_ERR(trans)) {
266		ret = PTR_ERR(trans);
267		trans = NULL;
268		goto out;
269	}
270	drop_args.path = path;
271	drop_args.start = drop_start;
272	drop_args.end = aligned_end;
273	drop_args.drop_cache = true;
274	ret = btrfs_drop_extents(trans, root, BTRFS_I(dst), &drop_args);
275	if (ret)
276		goto out;
277	ret = btrfs_insert_empty_item(trans, root, path, new_key, size);
278	if (ret)
279		goto out;
280
281	write_extent_buffer(path->nodes[0], inline_data,
282			    btrfs_item_ptr_offset(path->nodes[0],
283						  path->slots[0]),
284			    size);
285	btrfs_update_inode_bytes(BTRFS_I(dst), datal, drop_args.bytes_found);
286	btrfs_set_inode_full_sync(BTRFS_I(dst));
287	ret = btrfs_inode_set_file_extent_range(BTRFS_I(dst), 0, aligned_end);
288out:
289	if (!ret && !trans) {
290		/*
291		 * No transaction here means we copied the inline extent into a
292		 * page of the destination inode.
293		 *
294		 * 1 unit to update inode item
295		 */
296		trans = btrfs_start_transaction(root, 1);
297		if (IS_ERR(trans)) {
298			ret = PTR_ERR(trans);
299			trans = NULL;
300		}
301	}
302	if (ret && trans) {
303		btrfs_abort_transaction(trans, ret);
304		btrfs_end_transaction(trans);
305	}
306	if (!ret)
307		*trans_out = trans;
308
309	return ret;
310
311copy_to_page:
312	/*
313	 * Release our path because we don't need it anymore and also because
314	 * copy_inline_to_page() needs to reserve data and metadata, which may
315	 * need to flush delalloc when we are low on available space and
316	 * therefore cause a deadlock if writeback of an inline extent needs to
317	 * write to the same leaf or an ordered extent completion needs to write
318	 * to the same leaf.
319	 */
320	btrfs_release_path(path);
321
322	ret = copy_inline_to_page(BTRFS_I(dst), new_key->offset,
323				  inline_data, size, datal, comp_type);
324	goto out;
325}
326
327/*
328 * Clone a range from inode file to another.
329 *
330 * @src:             Inode to clone from
331 * @inode:           Inode to clone to
332 * @off:             Offset within source to start clone from
333 * @olen:            Original length, passed by user, of range to clone
334 * @olen_aligned:    Block-aligned value of olen
335 * @destoff:         Offset within @inode to start clone
336 * @no_time_update:  Whether to update mtime/ctime on the target inode
337 */
338static int btrfs_clone(struct inode *src, struct inode *inode,
339		       const u64 off, const u64 olen, const u64 olen_aligned,
340		       const u64 destoff, int no_time_update)
341{
342	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
343	struct btrfs_path *path = NULL;
344	struct extent_buffer *leaf;
345	struct btrfs_trans_handle *trans;
346	char *buf = NULL;
347	struct btrfs_key key;
348	u32 nritems;
349	int slot;
350	int ret;
351	const u64 len = olen_aligned;
352	u64 last_dest_end = destoff;
353	u64 prev_extent_end = off;
354
355	ret = -ENOMEM;
356	buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
357	if (!buf)
358		return ret;
359
360	path = btrfs_alloc_path();
361	if (!path) {
362		kvfree(buf);
363		return ret;
364	}
365
366	path->reada = READA_FORWARD;
367	/* Clone data */
368	key.objectid = btrfs_ino(BTRFS_I(src));
369	key.type = BTRFS_EXTENT_DATA_KEY;
370	key.offset = off;
371
372	while (1) {
 
373		struct btrfs_file_extent_item *extent;
374		u64 extent_gen;
375		int type;
376		u32 size;
377		struct btrfs_key new_key;
378		u64 disko = 0, diskl = 0;
379		u64 datao = 0, datal = 0;
380		u8 comp;
381		u64 drop_start;
382
383		/* Note the key will change type as we walk through the tree */
 
384		ret = btrfs_search_slot(NULL, BTRFS_I(src)->root, &key, path,
385				0, 0);
386		if (ret < 0)
387			goto out;
388		/*
389		 * First search, if no extent item that starts at offset off was
390		 * found but the previous item is an extent item, it's possible
391		 * it might overlap our target range, therefore process it.
392		 */
393		if (key.offset == off && ret > 0 && path->slots[0] > 0) {
394			btrfs_item_key_to_cpu(path->nodes[0], &key,
395					      path->slots[0] - 1);
396			if (key.type == BTRFS_EXTENT_DATA_KEY)
397				path->slots[0]--;
398		}
399
400		nritems = btrfs_header_nritems(path->nodes[0]);
401process_slot:
402		if (path->slots[0] >= nritems) {
403			ret = btrfs_next_leaf(BTRFS_I(src)->root, path);
404			if (ret < 0)
405				goto out;
406			if (ret > 0)
407				break;
408			nritems = btrfs_header_nritems(path->nodes[0]);
409		}
410		leaf = path->nodes[0];
411		slot = path->slots[0];
412
413		btrfs_item_key_to_cpu(leaf, &key, slot);
414		if (key.type > BTRFS_EXTENT_DATA_KEY ||
415		    key.objectid != btrfs_ino(BTRFS_I(src)))
416			break;
417
418		ASSERT(key.type == BTRFS_EXTENT_DATA_KEY);
419
420		extent = btrfs_item_ptr(leaf, slot,
421					struct btrfs_file_extent_item);
422		extent_gen = btrfs_file_extent_generation(leaf, extent);
423		comp = btrfs_file_extent_compression(leaf, extent);
424		type = btrfs_file_extent_type(leaf, extent);
425		if (type == BTRFS_FILE_EXTENT_REG ||
426		    type == BTRFS_FILE_EXTENT_PREALLOC) {
427			disko = btrfs_file_extent_disk_bytenr(leaf, extent);
428			diskl = btrfs_file_extent_disk_num_bytes(leaf, extent);
429			datao = btrfs_file_extent_offset(leaf, extent);
430			datal = btrfs_file_extent_num_bytes(leaf, extent);
431		} else if (type == BTRFS_FILE_EXTENT_INLINE) {
432			/* Take upper bound, may be compressed */
433			datal = btrfs_file_extent_ram_bytes(leaf, extent);
434		}
435
436		/*
437		 * The first search might have left us at an extent item that
438		 * ends before our target range's start, can happen if we have
439		 * holes and NO_HOLES feature enabled.
440		 *
441		 * Subsequent searches may leave us on a file range we have
442		 * processed before - this happens due to a race with ordered
443		 * extent completion for a file range that is outside our source
444		 * range, but that range was part of a file extent item that
445		 * also covered a leading part of our source range.
446		 */
447		if (key.offset + datal <= prev_extent_end) {
448			path->slots[0]++;
449			goto process_slot;
450		} else if (key.offset >= off + len) {
451			break;
452		}
453
454		prev_extent_end = key.offset + datal;
455		size = btrfs_item_size(leaf, slot);
456		read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf, slot),
457				   size);
458
459		btrfs_release_path(path);
 
460
461		memcpy(&new_key, &key, sizeof(new_key));
462		new_key.objectid = btrfs_ino(BTRFS_I(inode));
463		if (off <= key.offset)
464			new_key.offset = key.offset + destoff - off;
465		else
466			new_key.offset = destoff;
467
468		/*
469		 * Deal with a hole that doesn't have an extent item that
470		 * represents it (NO_HOLES feature enabled).
471		 * This hole is either in the middle of the cloning range or at
472		 * the beginning (fully overlaps it or partially overlaps it).
473		 */
474		if (new_key.offset != last_dest_end)
475			drop_start = last_dest_end;
476		else
477			drop_start = new_key.offset;
478
479		if (type == BTRFS_FILE_EXTENT_REG ||
480		    type == BTRFS_FILE_EXTENT_PREALLOC) {
481			struct btrfs_replace_extent_info clone_info;
482
483			/*
484			 *    a  | --- range to clone ---|  b
485			 * | ------------- extent ------------- |
486			 */
487
488			/* Subtract range b */
489			if (key.offset + datal > off + len)
490				datal = off + len - key.offset;
491
492			/* Subtract range a */
493			if (off > key.offset) {
494				datao += off - key.offset;
495				datal -= off - key.offset;
496			}
497
498			clone_info.disk_offset = disko;
499			clone_info.disk_len = diskl;
500			clone_info.data_offset = datao;
501			clone_info.data_len = datal;
502			clone_info.file_offset = new_key.offset;
503			clone_info.extent_buf = buf;
504			clone_info.is_new_extent = false;
505			clone_info.update_times = !no_time_update;
506			ret = btrfs_replace_file_extents(BTRFS_I(inode), path,
507					drop_start, new_key.offset + datal - 1,
508					&clone_info, &trans);
509			if (ret)
510				goto out;
511		} else {
512			ASSERT(type == BTRFS_FILE_EXTENT_INLINE);
513			/*
514			 * Inline extents always have to start at file offset 0
515			 * and can never be bigger then the sector size. We can
516			 * never clone only parts of an inline extent, since all
517			 * reflink operations must start at a sector size aligned
518			 * offset, and the length must be aligned too or end at
519			 * the i_size (which implies the whole inlined data).
520			 */
521			ASSERT(key.offset == 0);
522			ASSERT(datal <= fs_info->sectorsize);
523			if (WARN_ON(type != BTRFS_FILE_EXTENT_INLINE) ||
524			    WARN_ON(key.offset != 0) ||
525			    WARN_ON(datal > fs_info->sectorsize)) {
526				ret = -EUCLEAN;
527				goto out;
528			}
529
530			ret = clone_copy_inline_extent(inode, path, &new_key,
531						       drop_start, datal, size,
532						       comp, buf, &trans);
533			if (ret)
534				goto out;
535		}
536
537		btrfs_release_path(path);
538
539		/*
540		 * Whenever we share an extent we update the last_reflink_trans
541		 * of each inode to the current transaction. This is needed to
542		 * make sure fsync does not log multiple checksum items with
543		 * overlapping ranges (because some extent items might refer
544		 * only to sections of the original extent). For the destination
545		 * inode we do this regardless of the generation of the extents
546		 * or even if they are inline extents or explicit holes, to make
547		 * sure a full fsync does not skip them. For the source inode,
548		 * we only need to update last_reflink_trans in case it's a new
549		 * extent that is not a hole or an inline extent, to deal with
550		 * the checksums problem on fsync.
551		 */
552		if (extent_gen == trans->transid && disko > 0)
553			BTRFS_I(src)->last_reflink_trans = trans->transid;
554
555		BTRFS_I(inode)->last_reflink_trans = trans->transid;
556
557		last_dest_end = ALIGN(new_key.offset + datal,
558				      fs_info->sectorsize);
559		ret = clone_finish_inode_update(trans, inode, last_dest_end,
560						destoff, olen, no_time_update);
561		if (ret)
562			goto out;
563		if (new_key.offset + datal >= destoff + len)
564			break;
565
566		btrfs_release_path(path);
567		key.offset = prev_extent_end;
568
569		if (fatal_signal_pending(current)) {
570			ret = -EINTR;
571			goto out;
572		}
573
574		cond_resched();
575	}
576	ret = 0;
577
578	if (last_dest_end < destoff + len) {
579		/*
580		 * We have an implicit hole that fully or partially overlaps our
581		 * cloning range at its end. This means that we either have the
582		 * NO_HOLES feature enabled or the implicit hole happened due to
583		 * mixing buffered and direct IO writes against this file.
584		 */
585		btrfs_release_path(path);
 
586
587		/*
588		 * When using NO_HOLES and we are cloning a range that covers
589		 * only a hole (no extents) into a range beyond the current
590		 * i_size, punching a hole in the target range will not create
591		 * an extent map defining a hole, because the range starts at or
592		 * beyond current i_size. If the file previously had an i_size
593		 * greater than the new i_size set by this clone operation, we
594		 * need to make sure the next fsync is a full fsync, so that it
595		 * detects and logs a hole covering a range from the current
596		 * i_size to the new i_size. If the clone range covers extents,
597		 * besides a hole, then we know the full sync flag was already
598		 * set by previous calls to btrfs_replace_file_extents() that
599		 * replaced file extent items.
600		 */
601		if (last_dest_end >= i_size_read(inode))
602			btrfs_set_inode_full_sync(BTRFS_I(inode));
603
604		ret = btrfs_replace_file_extents(BTRFS_I(inode), path,
605				last_dest_end, destoff + len - 1, NULL, &trans);
606		if (ret)
607			goto out;
608
609		ret = clone_finish_inode_update(trans, inode, destoff + len,
610						destoff, olen, no_time_update);
611	}
612
613out:
614	btrfs_free_path(path);
615	kvfree(buf);
616	clear_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &BTRFS_I(inode)->runtime_flags);
617
618	return ret;
619}
620
621static void btrfs_double_extent_unlock(struct inode *inode1, u64 loff1,
622				       struct inode *inode2, u64 loff2, u64 len)
623{
624	unlock_extent(&BTRFS_I(inode1)->io_tree, loff1, loff1 + len - 1, NULL);
625	unlock_extent(&BTRFS_I(inode2)->io_tree, loff2, loff2 + len - 1, NULL);
626}
627
628static void btrfs_double_extent_lock(struct inode *inode1, u64 loff1,
629				     struct inode *inode2, u64 loff2, u64 len)
630{
631	u64 range1_end = loff1 + len - 1;
632	u64 range2_end = loff2 + len - 1;
633
634	if (inode1 < inode2) {
635		swap(inode1, inode2);
636		swap(loff1, loff2);
637		swap(range1_end, range2_end);
638	} else if (inode1 == inode2 && loff2 < loff1) {
639		swap(loff1, loff2);
640		swap(range1_end, range2_end);
641	}
642
643	lock_extent(&BTRFS_I(inode1)->io_tree, loff1, range1_end, NULL);
644	lock_extent(&BTRFS_I(inode2)->io_tree, loff2, range2_end, NULL);
645
646	btrfs_assert_inode_range_clean(BTRFS_I(inode1), loff1, range1_end);
647	btrfs_assert_inode_range_clean(BTRFS_I(inode2), loff2, range2_end);
648}
649
650static void btrfs_double_mmap_lock(struct inode *inode1, struct inode *inode2)
651{
652	if (inode1 < inode2)
653		swap(inode1, inode2);
654	down_write(&BTRFS_I(inode1)->i_mmap_lock);
655	down_write_nested(&BTRFS_I(inode2)->i_mmap_lock, SINGLE_DEPTH_NESTING);
656}
657
658static void btrfs_double_mmap_unlock(struct inode *inode1, struct inode *inode2)
659{
660	up_write(&BTRFS_I(inode1)->i_mmap_lock);
661	up_write(&BTRFS_I(inode2)->i_mmap_lock);
662}
663
664static int btrfs_extent_same_range(struct inode *src, u64 loff, u64 len,
665				   struct inode *dst, u64 dst_loff)
666{
667	struct btrfs_fs_info *fs_info = BTRFS_I(src)->root->fs_info;
668	const u64 bs = fs_info->sb->s_blocksize;
669	int ret;
670
671	/*
672	 * Lock destination range to serialize with concurrent readahead() and
673	 * source range to serialize with relocation.
674	 */
675	btrfs_double_extent_lock(src, loff, dst, dst_loff, len);
676	ret = btrfs_clone(src, dst, loff, len, ALIGN(len, bs), dst_loff, 1);
677	btrfs_double_extent_unlock(src, loff, dst, dst_loff, len);
678
679	btrfs_btree_balance_dirty(fs_info);
680
681	return ret;
682}
683
684static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
685			     struct inode *dst, u64 dst_loff)
686{
687	int ret = 0;
688	u64 i, tail_len, chunk_count;
689	struct btrfs_root *root_dst = BTRFS_I(dst)->root;
690
691	spin_lock(&root_dst->root_item_lock);
692	if (root_dst->send_in_progress) {
693		btrfs_warn_rl(root_dst->fs_info,
694"cannot deduplicate to root %llu while send operations are using it (%d in progress)",
695			      root_dst->root_key.objectid,
696			      root_dst->send_in_progress);
697		spin_unlock(&root_dst->root_item_lock);
698		return -EAGAIN;
699	}
700	root_dst->dedupe_in_progress++;
701	spin_unlock(&root_dst->root_item_lock);
702
703	tail_len = olen % BTRFS_MAX_DEDUPE_LEN;
704	chunk_count = div_u64(olen, BTRFS_MAX_DEDUPE_LEN);
705
706	for (i = 0; i < chunk_count; i++) {
707		ret = btrfs_extent_same_range(src, loff, BTRFS_MAX_DEDUPE_LEN,
708					      dst, dst_loff);
709		if (ret)
710			goto out;
711
712		loff += BTRFS_MAX_DEDUPE_LEN;
713		dst_loff += BTRFS_MAX_DEDUPE_LEN;
714	}
715
716	if (tail_len > 0)
717		ret = btrfs_extent_same_range(src, loff, tail_len, dst, dst_loff);
718out:
719	spin_lock(&root_dst->root_item_lock);
720	root_dst->dedupe_in_progress--;
721	spin_unlock(&root_dst->root_item_lock);
722
723	return ret;
724}
725
726static noinline int btrfs_clone_files(struct file *file, struct file *file_src,
727					u64 off, u64 olen, u64 destoff)
728{
729	struct inode *inode = file_inode(file);
730	struct inode *src = file_inode(file_src);
731	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
732	int ret;
733	int wb_ret;
734	u64 len = olen;
735	u64 bs = fs_info->sb->s_blocksize;
736
737	/*
738	 * VFS's generic_remap_file_range_prep() protects us from cloning the
739	 * eof block into the middle of a file, which would result in corruption
740	 * if the file size is not blocksize aligned. So we don't need to check
741	 * for that case here.
742	 */
743	if (off + len == src->i_size)
744		len = ALIGN(src->i_size, bs) - off;
745
746	if (destoff > inode->i_size) {
747		const u64 wb_start = ALIGN_DOWN(inode->i_size, bs);
748
749		ret = btrfs_cont_expand(BTRFS_I(inode), inode->i_size, destoff);
750		if (ret)
751			return ret;
752		/*
753		 * We may have truncated the last block if the inode's size is
754		 * not sector size aligned, so we need to wait for writeback to
755		 * complete before proceeding further, otherwise we can race
756		 * with cloning and attempt to increment a reference to an
757		 * extent that no longer exists (writeback completed right after
758		 * we found the previous extent covering eof and before we
759		 * attempted to increment its reference count).
760		 */
761		ret = btrfs_wait_ordered_range(inode, wb_start,
762					       destoff - wb_start);
763		if (ret)
764			return ret;
765	}
766
767	/*
768	 * Lock destination range to serialize with concurrent readahead() and
769	 * source range to serialize with relocation.
770	 */
771	btrfs_double_extent_lock(src, off, inode, destoff, len);
772	ret = btrfs_clone(src, inode, off, olen, len, destoff, 0);
773	btrfs_double_extent_unlock(src, off, inode, destoff, len);
774
775	/*
776	 * We may have copied an inline extent into a page of the destination
777	 * range, so wait for writeback to complete before truncating pages
778	 * from the page cache. This is a rare case.
779	 */
780	wb_ret = btrfs_wait_ordered_range(inode, destoff, len);
781	ret = ret ? ret : wb_ret;
782	/*
783	 * Truncate page cache pages so that future reads will see the cloned
784	 * data immediately and not the previous data.
785	 */
786	truncate_inode_pages_range(&inode->i_data,
787				round_down(destoff, PAGE_SIZE),
788				round_up(destoff + len, PAGE_SIZE) - 1);
789
790	btrfs_btree_balance_dirty(fs_info);
791
792	return ret;
793}
794
795static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in,
796				       struct file *file_out, loff_t pos_out,
797				       loff_t *len, unsigned int remap_flags)
798{
799	struct inode *inode_in = file_inode(file_in);
800	struct inode *inode_out = file_inode(file_out);
801	u64 bs = BTRFS_I(inode_out)->root->fs_info->sb->s_blocksize;
 
802	u64 wb_len;
803	int ret;
804
805	if (!(remap_flags & REMAP_FILE_DEDUP)) {
806		struct btrfs_root *root_out = BTRFS_I(inode_out)->root;
807
808		if (btrfs_root_readonly(root_out))
809			return -EROFS;
810
811		ASSERT(inode_in->i_sb == inode_out->i_sb);
 
 
812	}
813
814	/* Don't make the dst file partly checksummed */
815	if ((BTRFS_I(inode_in)->flags & BTRFS_INODE_NODATASUM) !=
816	    (BTRFS_I(inode_out)->flags & BTRFS_INODE_NODATASUM)) {
817		return -EINVAL;
818	}
819
820	/*
821	 * Now that the inodes are locked, we need to start writeback ourselves
822	 * and can not rely on the writeback from the VFS's generic helper
823	 * generic_remap_file_range_prep() because:
824	 *
825	 * 1) For compression we must call filemap_fdatawrite_range() range
826	 *    twice (btrfs_fdatawrite_range() does it for us), and the generic
827	 *    helper only calls it once;
828	 *
829	 * 2) filemap_fdatawrite_range(), called by the generic helper only
830	 *    waits for the writeback to complete, i.e. for IO to be done, and
831	 *    not for the ordered extents to complete. We need to wait for them
832	 *    to complete so that new file extent items are in the fs tree.
833	 */
834	if (*len == 0 && !(remap_flags & REMAP_FILE_DEDUP))
835		wb_len = ALIGN(inode_in->i_size, bs) - ALIGN_DOWN(pos_in, bs);
836	else
837		wb_len = ALIGN(*len, bs);
838
839	/*
 
 
 
 
 
 
 
 
 
840	 * Workaround to make sure NOCOW buffered write reach disk as NOCOW.
841	 *
842	 * Btrfs' back references do not have a block level granularity, they
843	 * work at the whole extent level.
844	 * NOCOW buffered write without data space reserved may not be able
845	 * to fall back to CoW due to lack of data space, thus could cause
846	 * data loss.
847	 *
848	 * Here we take a shortcut by flushing the whole inode, so that all
849	 * nocow write should reach disk as nocow before we increase the
850	 * reference of the extent. We could do better by only flushing NOCOW
851	 * data, but that needs extra accounting.
852	 *
853	 * Also we don't need to check ASYNC_EXTENT, as async extent will be
854	 * CoWed anyway, not affecting nocow part.
855	 */
856	ret = filemap_flush(inode_in->i_mapping);
857	if (ret < 0)
858		return ret;
859
860	ret = btrfs_wait_ordered_range(inode_in, ALIGN_DOWN(pos_in, bs),
861				       wb_len);
862	if (ret < 0)
863		return ret;
864	ret = btrfs_wait_ordered_range(inode_out, ALIGN_DOWN(pos_out, bs),
865				       wb_len);
866	if (ret < 0)
867		return ret;
868
869	return generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
870					    len, remap_flags);
871}
872
873static bool file_sync_write(const struct file *file)
874{
875	if (file->f_flags & (__O_SYNC | O_DSYNC))
876		return true;
877	if (IS_SYNC(file_inode(file)))
878		return true;
879
880	return false;
881}
882
883loff_t btrfs_remap_file_range(struct file *src_file, loff_t off,
884		struct file *dst_file, loff_t destoff, loff_t len,
885		unsigned int remap_flags)
886{
887	struct inode *src_inode = file_inode(src_file);
888	struct inode *dst_inode = file_inode(dst_file);
889	bool same_inode = dst_inode == src_inode;
890	int ret;
891
892	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
893		return -EINVAL;
894
895	if (same_inode) {
896		btrfs_inode_lock(BTRFS_I(src_inode), BTRFS_ILOCK_MMAP);
897	} else {
898		lock_two_nondirectories(src_inode, dst_inode);
899		btrfs_double_mmap_lock(src_inode, dst_inode);
900	}
901
902	ret = btrfs_remap_file_range_prep(src_file, off, dst_file, destoff,
903					  &len, remap_flags);
904	if (ret < 0 || len == 0)
905		goto out_unlock;
906
907	if (remap_flags & REMAP_FILE_DEDUP)
908		ret = btrfs_extent_same(src_inode, off, len, dst_inode, destoff);
909	else
910		ret = btrfs_clone_files(dst_file, src_file, off, len, destoff);
911
912out_unlock:
913	if (same_inode) {
914		btrfs_inode_unlock(BTRFS_I(src_inode), BTRFS_ILOCK_MMAP);
915	} else {
916		btrfs_double_mmap_unlock(src_inode, dst_inode);
917		unlock_two_nondirectories(src_inode, dst_inode);
918	}
919
920	/*
921	 * If either the source or the destination file was opened with O_SYNC,
922	 * O_DSYNC or has the S_SYNC attribute, fsync both the destination and
923	 * source files/ranges, so that after a successful return (0) followed
924	 * by a power failure results in the reflinked data to be readable from
925	 * both files/ranges.
926	 */
927	if (ret == 0 && len > 0 &&
928	    (file_sync_write(src_file) || file_sync_write(dst_file))) {
929		ret = btrfs_sync_file(src_file, off, off + len - 1, 0);
930		if (ret == 0)
931			ret = btrfs_sync_file(dst_file, destoff,
932					      destoff + len - 1, 0);
933	}
934
935	return ret < 0 ? ret : len;
936}