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2023-12-15btrfs: migrate subpage code to folio interfacesGravatar Qu Wenruo 1-2/+3
Although subpage itself is conflicting with higher folio, since subpage (sectorsize < PAGE_SIZE and nodesize < PAGE_SIZE) means we will never need higher order folio, there is a hidden pitfall: - btrfs_page_*() helpers Those helpers are an abstraction to handle both subpage and non-subpage cases, which means we're going to pass pages pointers to those helpers. And since those helpers are shared between data and metadata paths, it's unavoidable to let them to handle folios, including higher order folios). Meanwhile for true subpage case, we should only have a single page backed folios anyway, thus add a new ASSERT() for btrfs_subpage_assert() to ensure that. Also since those helpers are shared between both data and metadata, add some extra ASSERT()s for data path to make sure we only get single page backed folio for now. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-12-15btrfs: use the flags of an extent map to identify the compression typeGravatar Filipe Manana 1-1/+1
Currently, in struct extent_map, we use an unsigned int (32 bits) to identify the compression type of an extent and an unsigned long (64 bits on a 64 bits platform, 32 bits otherwise) for flags. We are only using 6 different flags, so an unsigned long is excessive and we can use flags to identify the compression type instead of using a dedicated 32 bits field. We can easily have tens or hundreds of thousands (or more) of extent maps on busy and large filesystems, specially with compression enabled or many or large files with tons of small extents. So it's convenient to have the extent_map structure as small as possible in order to use less memory. So remove the compression type field from struct extent_map, use flags to identify the compression type and shorten the flags field from an unsigned long to a u32. This saves 8 bytes (on 64 bits platforms) and reduces the size of the structure from 136 bytes down to 128 bytes, using now only two cache lines, and increases the number of extent maps we can have per 4K page from 30 to 32. By using a u32 for the flags instead of an unsigned long, we no longer use test_bit(), set_bit() and clear_bit(), but that level of atomicity is not needed as most flags are never cleared once set (before adding an extent map to the tree), and the ones that can be cleared or set after an extent map is added to the tree, are always performed while holding the write lock on the extent map tree, while the reader holds a lock on the tree or tests for a flag that never changes once the extent map is in the tree (such as compression flags). Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-30Merge tag 'for-6.7-tag' of ↵Gravatar Linus Torvalds 1-81/+127
git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux Pull btrfs updates from David Sterba: "New features: - raid-stripe-tree New tree for logical file extent mapping where the physical mapping may not match on multiple devices. This is now used in zoned mode to implement RAID0/RAID1* profiles, but can be used in non-zoned mode as well. The support for RAID56 is in development and will eventually fix the problems with the current implementation. This is a backward incompatible feature and has to be enabled at mkfs time. - simple quota accounting (squota) A simplified mode of qgroup that accounts all space on the initial extent owners (a subvolume), the snapshots are then cheap to create and delete. The deletion of snapshots in fully accounting qgroups is a known CPU/IO performance bottleneck. The squota is not suitable for the general use case but works well for containers where the original subvolume exists for the whole time. This is a backward incompatible feature as it needs extending some structures, but can be enabled on an existing filesystem. - temporary filesystem fsid (temp_fsid) The fsid identifies a filesystem and is hard coded in the structures, which disallows mounting the same fsid found on different devices. For a single device filesystem this is not strictly necessary, a new temporary fsid can be generated on mount e.g. after a device is cloned. This will be used by Steam Deck for root partition A/B testing, or can be used for VM root images. Other user visible changes: - filesystems with partially finished metadata_uuid conversion cannot be mounted anymore and the uuid fixup has to be done by btrfs-progs (btrfstune). Performance improvements: - reduce reservations for checksum deletions (with enabled free space tree by factor of 4), on a sample workload on file with many extents the deletion time decreased by 12% - make extent state merges more efficient during insertions, reduce rb-tree iterations (run time of critical functions reduced by 5%) Core changes: - the integrity check functionality has been removed, this was a debugging feature and removal does not affect other integrity checks like checksums or tree-checker - space reservation changes: - more efficient delayed ref reservations, this avoids building up too much work or overusing or exhausting the global block reserve in some situations - move delayed refs reservation to the transaction start time, this prevents some ENOSPC corner cases related to exhaustion of global reserve - improvements in reducing excessive reservations for block group items - adjust overcommit logic in near full situations, account for one more chunk to eventually allocate metadata chunk, this is mostly relevant for small filesystems (<10GiB) - single device filesystems are scanned but not registered (except seed devices), this allows temp_fsid to work - qgroup iterations do not need GFP_ATOMIC allocations anymore - cleanups, refactoring, reduced data structure size, function parameter simplifications, error handling fixes" * tag 'for-6.7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (156 commits) btrfs: open code timespec64 in struct btrfs_inode btrfs: remove redundant log root tree index assignment during log sync btrfs: remove redundant initialization of variable dirty in btrfs_update_time() btrfs: sysfs: show temp_fsid feature btrfs: disable the device add feature for temp-fsid btrfs: disable the seed feature for temp-fsid btrfs: update comment for temp-fsid, fsid, and metadata_uuid btrfs: remove pointless empty log context list check when syncing log btrfs: update comment for struct btrfs_inode::lock btrfs: remove pointless barrier from btrfs_sync_file() btrfs: add and use helpers for reading and writing last_trans_committed btrfs: add and use helpers for reading and writing fs_info->generation btrfs: add and use helpers for reading and writing log_transid btrfs: add and use helpers for reading and writing last_log_commit btrfs: support cloned-device mount capability btrfs: add helper function find_fsid_by_disk btrfs: stop reserving excessive space for block group item insertions btrfs: stop reserving excessive space for block group item updates btrfs: reorder btrfs_inode to fill gaps btrfs: open code btrfs_ordered_inode_tree in btrfs_inode ...
2023-10-23btrfs: fix unwritten extent buffer after snapshotting a new subvolumeGravatar Filipe Manana 1-3/+4
When creating a snapshot of a subvolume that was created in the current transaction, we can end up not persisting a dirty extent buffer that is referenced by the snapshot, resulting in IO errors due to checksum failures when trying to read the extent buffer later from disk. A sequence of steps that leads to this is the following: 1) At ioctl.c:create_subvol() we allocate an extent buffer, with logical address 36007936, for the leaf/root of a new subvolume that has an ID of 291. We mark the extent buffer as dirty, and at this point the subvolume tree has a single node/leaf which is also its root (level 0); 2) We no longer commit the transaction used to create the subvolume at create_subvol(). We used to, but that was recently removed in commit 1b53e51a4a8f ("btrfs: don't commit transaction for every subvol create"); 3) The transaction used to create the subvolume has an ID of 33, so the extent buffer 36007936 has a generation of 33; 4) Several updates happen to subvolume 291 during transaction 33, several files created and its tree height changes from 0 to 1, so we end up with a new root at level 1 and the extent buffer 36007936 is now a leaf of that new root node, which is extent buffer 36048896. The commit root remains as 36007936, since we are still at transaction 33; 5) Creation of a snapshot of subvolume 291, with an ID of 292, starts at ioctl.c:create_snapshot(). This triggers a commit of transaction 33 and we end up at transaction.c:create_pending_snapshot(), in the critical section of a transaction commit. There we COW the root of subvolume 291, which is extent buffer 36048896. The COW operation returns extent buffer 36048896, since there's no need to COW because the extent buffer was created in this transaction and it was not written yet. The we call btrfs_copy_root() against the root node 36048896. During this operation we allocate a new extent buffer to turn into the root node of the snapshot, copy the contents of the root node 36048896 into this snapshot root extent buffer, set the owner to 292 (the ID of the snapshot), etc, and then we call btrfs_inc_ref(). This will create a delayed reference for each leaf pointed by the root node with a reference root of 292 - this includes a reference for the leaf 36007936. After that we set the bit BTRFS_ROOT_FORCE_COW in the root's state. Then we call btrfs_insert_dir_item(), to create the directory entry in in the tree of subvolume 291 that points to the snapshot. This ends up needing to modify leaf 36007936 to insert the respective directory items. Because the bit BTRFS_ROOT_FORCE_COW is set for the root's state, we need to COW the leaf. We end up at btrfs_force_cow_block() and then at update_ref_for_cow(). At update_ref_for_cow() we call btrfs_block_can_be_shared() which returns false, despite the fact the leaf 36007936 is shared - the subvolume's root and the snapshot's root point to that leaf. The reason that it incorrectly returns false is because the commit root of the subvolume is extent buffer 36007936 - it was the initial root of the subvolume when we created it. So btrfs_block_can_be_shared() which has the following logic: int btrfs_block_can_be_shared(struct btrfs_root *root, struct extent_buffer *buf) { if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) && buf != root->node && buf != root->commit_root && (btrfs_header_generation(buf) <= btrfs_root_last_snapshot(&root->root_item) || btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC))) return 1; return 0; } Returns false (0) since 'buf' (extent buffer 36007936) matches the root's commit root. As a result, at update_ref_for_cow(), we don't check for the number of references for extent buffer 36007936, we just assume it's not shared and therefore that it has only 1 reference, so we set the local variable 'refs' to 1. Later on, in the final if-else statement at update_ref_for_cow(): static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *cow, int *last_ref) { (...) if (refs > 1) { (...) } else { (...) btrfs_clear_buffer_dirty(trans, buf); *last_ref = 1; } } So we mark the extent buffer 36007936 as not dirty, and as a result we don't write it to disk later in the transaction commit, despite the fact that the snapshot's root points to it. Attempting to access the leaf or dumping the tree for example shows that the extent buffer was not written: $ btrfs inspect-internal dump-tree -t 292 /dev/sdb btrfs-progs v6.2.2 file tree key (292 ROOT_ITEM 33) node 36110336 level 1 items 2 free space 119 generation 33 owner 292 node 36110336 flags 0x1(WRITTEN) backref revision 1 checksum stored a8103e3e checksum calced a8103e3e fs uuid 90c9a46f-ae9f-4626-9aff-0cbf3e2e3a79 chunk uuid e8c9c885-78f4-4d31-85fe-89e5f5fd4a07 key (256 INODE_ITEM 0) block 36007936 gen 33 key (257 EXTENT_DATA 0) block 36052992 gen 33 checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29 checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29 total bytes 107374182400 bytes used 38572032 uuid 90c9a46f-ae9f-4626-9aff-0cbf3e2e3a79 The respective on disk region is full of zeroes as the device was trimmed at mkfs time. Obviously 'btrfs check' also detects and complains about this: $ btrfs check /dev/sdb Opening filesystem to check... Checking filesystem on /dev/sdb UUID: 90c9a46f-ae9f-4626-9aff-0cbf3e2e3a79 generation: 33 (33) [1/7] checking root items [2/7] checking extents checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29 checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29 checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29 bad tree block 36007936, bytenr mismatch, want=36007936, have=0 owner ref check failed [36007936 4096] ERROR: errors found in extent allocation tree or chunk allocation [3/7] checking free space tree [4/7] checking fs roots checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29 checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29 checksum verify failed on 36007936 wanted 0x00000000 found 0x86005f29 bad tree block 36007936, bytenr mismatch, want=36007936, have=0 The following tree block(s) is corrupted in tree 292: tree block bytenr: 36110336, level: 1, node key: (256, 1, 0) root 292 root dir 256 not found ERROR: errors found in fs roots found 38572032 bytes used, error(s) found total csum bytes: 16048 total tree bytes: 1265664 total fs tree bytes: 1118208 total extent tree bytes: 65536 btree space waste bytes: 562598 file data blocks allocated: 65978368 referenced 36569088 Fix this by updating btrfs_block_can_be_shared() to consider that an extent buffer may be shared if it matches the commit root and if its generation matches the current transaction's generation. This can be reproduced with the following script: $ cat test.sh #!/bin/bash MNT=/mnt/sdi DEV=/dev/sdi # Use a filesystem with a 64K node size so that we have the same node # size on every machine regardless of its page size (on x86_64 default # node size is 16K due to the 4K page size, while on PPC it's 64K by # default). This way we can make sure we are able to create a btree for # the subvolume with a height of 2. mkfs.btrfs -f -n 64K $DEV mount $DEV $MNT btrfs subvolume create $MNT/subvol # Create a few empty files on the subvolume, this bumps its btree # height to 2 (root node at level 1 and 2 leaves). for ((i = 1; i <= 300; i++)); do echo -n > $MNT/subvol/file_$i done btrfs subvolume snapshot -r $MNT/subvol $MNT/subvol/snap umount $DEV btrfs check $DEV Running it on a 6.5 kernel (or any 6.6-rc kernel at the moment): $ ./test.sh Create subvolume '/mnt/sdi/subvol' Create a readonly snapshot of '/mnt/sdi/subvol' in '/mnt/sdi/subvol/snap' Opening filesystem to check... Checking filesystem on /dev/sdi UUID: bbdde2ff-7d02-45ca-8a73-3c36f23755a1 [1/7] checking root items [2/7] checking extents parent transid verify failed on 30539776 wanted 7 found 5 parent transid verify failed on 30539776 wanted 7 found 5 parent transid verify failed on 30539776 wanted 7 found 5 Ignoring transid failure owner ref check failed [30539776 65536] ERROR: errors found in extent allocation tree or chunk allocation [3/7] checking free space tree [4/7] checking fs roots parent transid verify failed on 30539776 wanted 7 found 5 Ignoring transid failure Wrong key of child node/leaf, wanted: (256, 1, 0), have: (2, 132, 0) Wrong generation of child node/leaf, wanted: 5, have: 7 root 257 root dir 256 not found ERROR: errors found in fs roots found 917504 bytes used, error(s) found total csum bytes: 0 total tree bytes: 851968 total fs tree bytes: 393216 total extent tree bytes: 65536 btree space waste bytes: 736550 file data blocks allocated: 0 referenced 0 A test case for fstests will follow soon. Fixes: 1b53e51a4a8f ("btrfs: don't commit transaction for every subvol create") CC: stable@vger.kernel.org # 6.5+ Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: change test_range_bit to scan the whole rangeGravatar David Sterba 1-1/+1
The semantics of test_range_bit() with filled == 0 is now in it's own helper so test_range_bit will check the whole range unconditionally. The detection logic is flipped and assumes success by default and catches exceptions. Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: relocation: constify parameters where possibleGravatar David Sterba 1-28/+28
Lots of the functions in relocation.c don't change pointer parameters but lack the annotations. Add them and reformat according to current coding style if needed. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: relocation: return bool from btrfs_should_ignore_reloc_rootGravatar David Sterba 1-10/+9
btrfs_should_ignore_reloc_root() is a predicate so it should return bool. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: switch btrfs_backref_cache::is_reloc to boolGravatar David Sterba 1-1/+1
The btrfs_backref_cache::is_reloc is an indicator variable and should use a bool type. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: relocation: open code mapping_tree_initGravatar David Sterba 1-8/+2
There's only one user of mapping_tree_init, we don't need a helper for the simple initialization. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: relocation: switch bitfields to bool in reloc_controlGravatar David Sterba 1-9/+9
Use bool types for the indicators instead of bitfields. The structure size slightly grows but the new types are placed within the padding. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: relocation: use enum for stagesGravatar David Sterba 1-7/+9
Add an enum type for data relocation stages. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: relocation: use more natural types for tree_block bitfieldsGravatar David Sterba 1-4/+4
We don't need to use bitfields for tree_block::level and tree_block::key_ready, there's enough padding in the structure for proper types. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: track data relocation with simple quotaGravatar Boris Burkov 1-1/+48
Relocation data allocations are quite tricky for simple quotas. The basic data relocation sequence is (ignoring details that aren't relevant to this fix): - create a fake relocation data fs root - create a fake relocation inode in that root - for each data extent: - preallocate a data extent on behalf of the fake inode - copy over the data - for each extent - swap the refs so that the original file extent now refers to the new extent item - drop the fake root, dropping its refs on the old extents, which lets us delete them. Done naively, this results in storing an extent item in the extent tree whose owner_ref points at the relocation data root and a no-op squota recording, since the reloc root is not a legit fstree. So far, that's OK. The problem comes when you do the swap, and leave an extent item owned by this bogus root as the real permanent extents of the file. If the file then drops that ref, we free it and no-op account that against the fake relocation root. Essentially, this means that relocation is simple quota "extent laundering", since we re-own the extents into a fake root. Simple quotas very intentionally doesn't have a mechanism for transferring ownership of extents, as that is exactly the complicated thing we are trying to avoid with the new design. Further, it cannot be correctly done in this case, since at the time you create the new "real" refs, there is no way to know which was the original owner before relocation unless we track it. Therefore, it makes more sense to trick the preallocation to handle relocation as a special case and note the proper owner ref from the beginning. That way, we never write out an extent item without the correct owner ref that it will eventually have. This could be done by wiring a special root parameter all the way through the allocation code path, but to avoid that special case touching all the code, take advantage of the serial nature of relocation to store the src root on the relocation root object. Then when we finish the prealloc, if it happens to be this case, prepare the delayed ref appropriately. We must also add logic to handle relocating adjacent extents with different owning roots. Those cannot be preallocated together in a cluster as it would lose the separate ownership information. This is obviously a smelly bit of code, but I think it is the best solution to the problem, given the relocation implementation. Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: track owning root in btrfs_refGravatar Boris Burkov 1-7/+11
While data extents require us to store additional inline refs to track the original owner on free, this information is available implicitly for metadata. It is found in the owner field of the header of the tree block. Even if other trees refer to this block and the original ref goes away, we will not rewrite that header field, so it will reliably give the original owner. In addition, there is a relocation case where a new data extent needs to have an owning root separate from the referring root wired through delayed refs. To use it for recording simple quota deltas, we need to wire this root id through from when we create the delayed ref until we fully process it. Store it in the generic btrfs_ref struct of the delayed ref. Signed-off-by: Boris Burkov <boris@bur.io> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: abort transaction on generation mismatch when marking eb as dirtyGravatar Filipe Manana 1-5/+5
When marking an extent buffer as dirty, at btrfs_mark_buffer_dirty(), we check if its generation matches the running transaction and if not we just print a warning. Such mismatch is an indicator that something really went wrong and only printing a warning message (and stack trace) is not enough to prevent a corruption. Allowing a transaction to commit with such an extent buffer will trigger an error if we ever try to read it from disk due to a generation mismatch with its parent generation. So abort the current transaction with -EUCLEAN if we notice a generation mismatch. For this we need to pass a transaction handle to btrfs_mark_buffer_dirty() which is always available except in test code, in which case we can pass NULL since it operates on dummy extent buffers and all test roots have a single node/leaf (root node at level 0). Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-10-12btrfs: drop __must_check annotationsGravatar David Sterba 1-1/+1
Drop all __must_check annotations because they're used in random functions and not consistently. All errors should be handled. Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21btrfs: remove v0 extent handlingGravatar Qu Wenruo 1-5/+6
The v0 extent item has been deprecated for a long time, and we don't have any report from the community either. So it's time to remove the v0 extent specific error handling, and just treat them as regular extent tree corruption. This patch would remove the btrfs_print_v0_err() helper, and enhance the involved error handling to treat them just as any extent tree corruption. No reports regarding v0 extents have been seen since the graceful handling was added in 2018. This involves: - btrfs_backref_add_tree_node() This change is a little tricky, the new code is changed to only handle BTRFS_TREE_BLOCK_REF_KEY and BTRFS_SHARED_BLOCK_REF_KEY. But this is safe, as we have rejected any unknown inline refs through btrfs_get_extent_inline_ref_type(). For keyed backrefs, we're safe to skip anything we don't know (that's if it can pass tree-checker in the first place). - btrfs_lookup_extent_info() - lookup_inline_extent_backref() - run_delayed_extent_op() - __btrfs_free_extent() - add_tree_block() Regular error handling of unexpected extent tree item, and abort transaction (if we have a trans handle). - remove_extent_data_ref() It's pretty much the same as the regular rejection of unknown backref key. But for this particular case, we can also remove a BUG_ON(). - extent_data_ref_count() We can remove the BTRFS_EXTENT_REF_V0_KEY BUG_ON(), as it would be rejected by the only caller. - btrfs_print_leaf() Remove the handling for BTRFS_EXTENT_REF_V0_KEY. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21btrfs: set page extent mapped after read_folio in relocate_one_pageGravatar Josef Bacik 1-3/+9
One of the CI runs triggered the following panic assertion failed: PagePrivate(page) && page->private, in fs/btrfs/subpage.c:229 ------------[ cut here ]------------ kernel BUG at fs/btrfs/subpage.c:229! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP CPU: 0 PID: 923660 Comm: btrfs Not tainted 6.5.0-rc3+ #1 pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) pc : btrfs_subpage_assert+0xbc/0xf0 lr : btrfs_subpage_assert+0xbc/0xf0 sp : ffff800093213720 x29: ffff800093213720 x28: ffff8000932138b4 x27: 000000000c280000 x26: 00000001b5d00000 x25: 000000000c281000 x24: 000000000c281fff x23: 0000000000001000 x22: 0000000000000000 x21: ffffff42b95bf880 x20: ffff42b9528e0000 x19: 0000000000001000 x18: ffffffffffffffff x17: 667274622f736620 x16: 6e69202c65746176 x15: 0000000000000028 x14: 0000000000000003 x13: 00000000002672d7 x12: 0000000000000000 x11: ffffcd3f0ccd9204 x10: ffffcd3f0554ae50 x9 : ffffcd3f0379528c x8 : ffff800093213428 x7 : 0000000000000000 x6 : ffffcd3f091771e8 x5 : ffff42b97f333948 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000000 x1 : ffff42b9556cde80 x0 : 000000000000004f Call trace: btrfs_subpage_assert+0xbc/0xf0 btrfs_subpage_set_dirty+0x38/0xa0 btrfs_page_set_dirty+0x58/0x88 relocate_one_page+0x204/0x5f0 relocate_file_extent_cluster+0x11c/0x180 relocate_data_extent+0xd0/0xf8 relocate_block_group+0x3d0/0x4e8 btrfs_relocate_block_group+0x2d8/0x490 btrfs_relocate_chunk+0x54/0x1a8 btrfs_balance+0x7f4/0x1150 btrfs_ioctl+0x10f0/0x20b8 __arm64_sys_ioctl+0x120/0x11d8 invoke_syscall.constprop.0+0x80/0xd8 do_el0_svc+0x6c/0x158 el0_svc+0x50/0x1b0 el0t_64_sync_handler+0x120/0x130 el0t_64_sync+0x194/0x198 Code: 91098021 b0007fa0 91346000 97e9c6d2 (d4210000) This is the same problem outlined in 17b17fcd6d44 ("btrfs: set_page_extent_mapped after read_folio in btrfs_cont_expand") , and the fix is the same. I originally looked for the same pattern elsewhere in our code, but mistakenly skipped over this code because I saw the page cache readahead before we set_page_extent_mapped, not realizing that this was only in the !page case, that we can still end up with a !uptodate page and then do the btrfs_read_folio further down. The fix here is the same as the above mentioned patch, move the set_page_extent_mapped call to after the btrfs_read_folio() block to make sure that we have the subpage blocksize stuff setup properly before using the page. CC: stable@vger.kernel.org # 6.1+ Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-21btrfs: make find_first_extent_bit() return a booleanGravatar Filipe Manana 1-4/+6
Currently find_first_extent_bit() returns a 0 if it found a range in the given io tree and 1 if it didn't find any. There's no need to return any errors, so make the return value a boolean and invert the logic to make more sense: return true if it found a range and false if it didn't find any range. Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-08-10btrfs: exit gracefully if reloc roots don't matchGravatar Qu Wenruo 1-8/+37
[BUG] Syzbot reported a crash that an ASSERT() got triggered inside prepare_to_merge(). [CAUSE] The root cause of the triggered ASSERT() is we can have a race between quota tree creation and relocation. This leads us to create a duplicated quota tree in the btrfs_read_fs_root() path, and since it's treated as fs tree, it would have ROOT_SHAREABLE flag, causing us to create a reloc tree for it. The bug itself is fixed by a dedicated patch for it, but this already taught us the ASSERT() is not something straightforward for developers. [ENHANCEMENT] Instead of using an ASSERT(), let's handle it gracefully and output extra info about the mismatch reloc roots to help debug. Also with the above ASSERT() removed, we can trigger ASSERT(0)s inside merge_reloc_roots() later. Also replace those ASSERT(0)s with WARN_ON()s. CC: stable@vger.kernel.org # 5.15+ Reported-by: syzbot+ae97a827ae1c3336bbb4@syzkaller.appspotmail.com Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-06-19btrfs: pass an ordered_extent to btrfs_reloc_clone_csumsGravatar Christoph Hellwig 1-21/+14
Both callers of btrfs_reloc_clone_csums allocate the ordered_extent that btrfs_reloc_clone_csums operates on. Switch them to use btrfs_alloc_ordered_extent instead of btrfs_add_ordered_extent and pass the ordered_extent to btrfs_reloc_clone_csums instead of doing an extra lookup. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-06-19btrfs: rename the bytenr field in struct btrfs_ordered_sum to logicalGravatar Christoph Hellwig 1-2/+2
btrfs_ordered_sum::bytendr stores a logical address. Make that clear by renaming it to ->logical. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-06-19btrfs: drop gfp from parameter extent state helpersGravatar David Sterba 1-3/+2
Now that all extent state bit helpers effectively take the GFP_NOFS mask (and GFP_NOWAIT is encoded in the bits) we can remove the parameter. This reduces stack consumption in many functions and simplifies a lot of code. Net effect on module on a release build: text data bss dec hex filename 1250432 20985 16088 1287505 13a551 pre/btrfs.ko 1247074 20985 16088 1284147 139833 post/btrfs.ko DELTA: -3358 Signed-off-by: David Sterba <dsterba@suse.com>
2023-06-19btrfs: open code set_extent_bitsGravatar David Sterba 1-5/+6
This helper calls set_extent_bit with two more parameters set to default values, but otherwise it's purpose is not clear. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-06-19btrfs: output affected files when relocation failsGravatar Qu Wenruo 1-0/+16
[PROBLEM] When relocation fails (mostly due to checksum mismatch), we only got very cryptic error messages like: BTRFS info (device dm-4): relocating block group 13631488 flags data BTRFS warning (device dm-4): csum failed root -9 ino 257 off 0 csum 0x373e1ae3 expected csum 0x98757625 mirror 1 BTRFS error (device dm-4): bdev /dev/mapper/test-scratch1 errs: wr 0, rd 0, flush 0, corrupt 1, gen 0 BTRFS info (device dm-4): balance: ended with status: -5 The end user has to decipher the above messages and use various tools to locate the affected files and find a way to fix the problem (mostly deleting the file). This is not an easy work even for experienced developer, not to mention the end users. [SCRUB IS DOING BETTER] By contrast, scrub is providing much better error messages: BTRFS error (device dm-4): unable to fixup (regular) error at logical 13631488 on dev /dev/mapper/test-scratch1 physical 13631488 BTRFS warning (device dm-4): checksum error at logical 13631488 on dev /dev/mapper/test-scratch1, physical 13631488, root 5, inode 257, offset 0, length 4096, links 1 (path: file) BTRFS info (device dm-4): scrub: finished on devid 1 with status: 0 Which provides the affected files directly to the end user. [IMPROVEMENT] Instead of the generic data checksum error messages, which is not doing a good job for data reloc inodes, this patch introduce a scrub like backref walking based solution. When a sector fails its checksum for data reloc inode, we go the following workflow: - Get the real logical bytenr For data reloc inode, the file offset is the offset inside the block group. Thus the real logical bytenr is @file_off + @block_group->start. - Do an extent type check If it's tree blocks it's much easier to handle, just go through all the tree block backref. - Do a backref walk and inode path resolution for data extents This is mostly the same as scrub. But unfortunately we can not reuse the same function as the output format is different. Now the new output would be more user friendly: BTRFS info (device dm-4): relocating block group 13631488 flags data BTRFS warning (device dm-4): csum failed root -9 ino 257 off 0 logical 13631488 csum 0x373e1ae3 expected csum 0x98757625 mirror 1 BTRFS warning (device dm-4): checksum error at logical 13631488 mirror 1 root 5 inode 257 offset 0 length 4096 links 1 (path: file) BTRFS error (device dm-4): bdev /dev/mapper/test-scratch1 errs: wr 0, rd 0, flush 0, corrupt 2, gen 0 BTRFS info (device dm-4): balance: ended with status: -5 Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-05-09btrfs: fix backref walking not returning all inode refsGravatar Filipe Manana 1-1/+1
When using the logical to ino ioctl v2, if the flag to ignore offsets of file extent items (BTRFS_LOGICAL_INO_ARGS_IGNORE_OFFSET) is given, the backref walking code ends up not returning references for all file offsets of an inode that point to the given logical bytenr. This happens since kernel 6.2, commit 6ce6ba534418 ("btrfs: use a single argument for extent offset in backref walking functions") because: 1) It mistakenly skipped the search for file extent items in a leaf that point to the target extent if that flag is given. Instead it should only skip the filtering done by check_extent_in_eb() - that is, it should not avoid the calls to that function (or find_extent_in_eb(), which uses it). 2) It was also not building a list of inode extent elements (struct extent_inode_elem) if we have multiple inode references for an extent when the ignore offset flag is given to the logical to ino ioctl - it would leave a single element, only the last one that was found. These stem from the confusing old interface for backref walking functions where we had an extent item offset argument that was a pointer to a u64 and another boolean argument that indicated if the offset should be ignored, but the pointer could be NULL. That NULL case is used by relocation, qgroup extent accounting and fiemap, simply to avoid building the inode extent list for each reference, as it's not necessary for those use cases and therefore avoids memory allocations and some computations. Fix this by adding a boolean argument to the backref walk context structure to indicate that the inode extent list should not be built, make relocation set that argument to true and fix the backref walking logic to skip the calls to check_extent_in_eb() and find_extent_in_eb() only if this new argument is true, instead of 'ignore_extent_item_pos' being true. A test case for fstests will be added soon, to provide cover not only for these cases but to the logical to ino ioctl in general as well, as currently we do not have a test case for it. Reported-by: Vladimir Panteleev <git@vladimir.panteleev.md> Link: https://lore.kernel.org/linux-btrfs/CAHhfkvwo=nmzrJSqZ2qMfF-rZB-ab6ahHnCD_sq9h4o8v+M7QQ@mail.gmail.com/ Fixes: 6ce6ba534418 ("btrfs: use a single argument for extent offset in backref walking functions") CC: stable@vger.kernel.org # 6.2+ Tested-by: Vladimir Panteleev <git@vladimir.panteleev.md> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-04-17btrfs: open code btrfs_bin_search()Gravatar Anand Jain 1-3/+3
btrfs_bin_search() is a simple wrapper that searches for the whole slots by calling btrfs_generic_bin_search() with the starting slot/first_slot preset to 0. This simple wrapper can be open coded as btrfs_bin_search(). Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2023-02-13btrfs: use PAGE_{ALIGN, ALIGNED, ALIGN_DOWN} macroGravatar Yushan Zhou 1-1/+1
The header file linux/mm.h provides PAGE_ALIGN, PAGE_ALIGNED, PAGE_ALIGN_DOWN macros. Use these macros to make code more concise. Signed-off-by: Yushan Zhou <katrinzhou@tencent.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: split the bio submission path into a separate fileGravatar Christoph Hellwig 1-0/+1
The code used by btrfs_submit_bio only interacts with the rest of volumes.c through __btrfs_map_block (which itself is a more generic version of two exported helpers) and does not really have anything to do with volumes.c. Create a new bio.c file and a bio.h header going along with it for the btrfs_bio-based storage layer, which will grow even more going forward. Also update the file with my copyright notice given that a large part of the moved code was written or rewritten by me. Reviewed-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: introduce a bitmap based csum range search functionGravatar Qu Wenruo 1-2/+2
Although we have an existing function, btrfs_lookup_csums_range(), to find all data checksums for a range, it's based on a btrfs_ordered_sum list. For the incoming RAID56 data checksum verification at RMW time, we don't want to waste time by allocating temporary memory. So this patch will introduce a new helper, btrfs_lookup_csums_bitmap(). It will use bitmap based result, which will be a perfect fit for later RAID56 usage. Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: concentrate all tree block parentness check parameters into one structureGravatar Qu Wenruo 1-3/+8
There are several different tree block parentness check parameters used across several helpers: - level Mandatory - transid Under most cases it's mandatory, but there are several backref cases which skips this check. - owner_root - first_key Utilized by most top-down tree search routine. Otherwise can be skipped. Those four members are not always mandatory checks, and some of them are the same u64, which means if some arguments got swapped compiler will not catch it. Furthermore if we're going to further expand the parentness check, we need to modify quite some helpers just to add one more parameter. This patch will concentrate all these members into a structure called btrfs_tree_parent_check, and pass that structure for the following helpers: - btrfs_read_extent_buffer() - read_tree_block() Signed-off-by: Qu Wenruo <wqu@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: pass btrfs_inode to btrfs_add_delayed_iputGravatar David Sterba 1-2/+2
The function is for internal interfaces so we should use the btrfs_inode. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: drop private_data parameter from extent_io_tree_initGravatar David Sterba 1-2/+1
All callers except one pass NULL, so the parameter can be dropped and the inode::io_tree initialization can be open coded. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: pass btrfs_inode to btrfs_inode_unlockGravatar David Sterba 1-1/+1
The function is for internal interfaces so we should use the btrfs_inode. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: pass btrfs_inode to btrfs_inode_lockGravatar David Sterba 1-1/+1
The function is for internal interfaces so we should use the btrfs_inode. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: use a structure to pass arguments to backref walking functionsGravatar Filipe Manana 1-8/+11
The public backref walking functions have quite a lot of arguments that are passed down the call stack to find_parent_nodes(), the core function of the backref walking code. The next patches in series will need to add even arguments to these functions that should be passed not only to find_parent_nodes(), but also to other functions used by the later (directly or even lower in the call stack). So create a structure to hold all these arguments and state used by the main backref walking function, find_parent_nodes(), and use it as the argument for the public backref walking functions iterate_extent_inodes(), btrfs_find_all_leafs() and btrfs_find_all_roots(). Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: use a single argument for extent offset in backref walking functionsGravatar Filipe Manana 1-1/+1
The interface for find_parent_nodes() has two extent offset related arguments: 1) One u64 pointer argument for the extent offset; 2) One boolean argument to tell if the extent offset should be ignored or not. These are confusing, becase the extent offset pointer can be NULL and in some cases callers pass a NULL value as a way to tell the backref walking code to ignore offsets in file extent items (and simply consider all file extent items that point to the target data extent). The boolean argument was added in commit c995ab3cda3f ("btrfs: add a flag to iterate_inodes_from_logical to find all extent refs for uncompressed extents"), but it was never really necessary, it was enough if it could find a way to get a NULL value passed to the "extent_item_pos" argument of find_parent_nodes(). The arguments are also passed to functions called by find_parent_nodes() and respective helper functions, which further makes everything more complicated than needed. Then we have several backref walking related functions that end up calling find_parent_nodes(), either directly or through some other function that they call, and for many we have to use an "extent_item_pos" (u64) argument and a boolean "ignore_offset" argument too. This is confusing and not really necessary. So use a single argument to specify the extent offset, as a simple u64 and not as a pointer, but using a special value of (u64)-1, defined as a documented constant, to indicate when the extent offset should be ignored. This is also preparation work for the upcoming patches in the series that add other arguments to find_parent_nodes() and other related functions that use it. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move super_block specific helpers into super.hGravatar Josef Bacik 1-0/+1
This will make syncing fs.h to user space a little easier if we can pull the super block specific helpers out of fs.h and put them in super.h. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move relocation prototypes into relocation.hGravatar Josef Bacik 1-0/+1
Move these out of ctree.h into relocation.h to cut down on code in ctree.h Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move file-item prototypes into their own headerGravatar Josef Bacik 1-0/+1
Move these prototypes out of ctree.h and into file-item.h. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move root tree prototypes to their own headerGravatar Josef Bacik 1-0/+1
Move all the root-tree.c prototypes to root-tree.h, and then update all the necessary files to include the new header. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move extent-tree helpers into their own header fileGravatar Josef Bacik 1-0/+1
Move all the extent tree related prototypes to extent-tree.h out of ctree.h, and then go include it everywhere needed so everything compiles. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: sink gfp_t parameter to btrfs_backref_iter_allocGravatar David Sterba 1-1/+1
There's only one caller that passes GFP_NOFS, we can drop the parameter an use the flags directly. Reviewed-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move accessor helpers into accessors.hGravatar Josef Bacik 1-0/+1
This is a large patch, but because they're all macros it's impossible to split up. Simply copy all of the item accessors in ctree.h and paste them in accessors.h, and then update any files to include the header so everything compiles. Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> [ reformat comments, style fixups ] Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move fs wide helpers out of ctree.hGravatar Josef Bacik 1-0/+1
We have several fs wide related helpers in ctree.h. The bulk of these are the incompat flag test helpers, but there are things such as btrfs_fs_closing() and the read only helpers that also aren't directly related to the ctree code. Move these into a fs.h header, which will serve as the location for file system wide related helpers. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: move flush related definitions to space-info.hGravatar Josef Bacik 1-0/+1
This code is used in space-info.c, move the definitions to space-info.h. Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: use a cached_state everywhere in relocationGravatar Josef Bacik 1-14/+26
All of the relocation code avoids using the cached state, despite everywhere using the normal lock_extent() // do something unlock_extent() pattern. Fix this by plumbing a cached state throughout all of these functions in order to allow for less tree searches. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-12-05btrfs: add a cached_state to try_lock_extentGravatar Josef Bacik 1-1/+1
With nowait becoming more pervasive throughout our codebase go ahead and add a cached_state to try_lock_extent(). This allows us to be faster about clearing the locked area if we have contention, and then gives us the same optimization for unlock if we are able to lock the range. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-09-29btrfs: add helper to replace extent map range with a new extent mapGravatar Filipe Manana 1-11/+3
We have several places that need to drop all the extent maps in a given file range and then add a new extent map for that range. Currently they call btrfs_drop_extent_map_range() to delete all extent maps in the range and then keep trying to add the new extent map in a loop that keeps retrying while the insertion of the new extent map fails with -EEXIST. So instead of repeating this logic, add a helper to extent_map.c that does these steps and name it btrfs_replace_extent_map_range(). Also add a comment about why the retry loop is necessary. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
2022-09-29btrfs: move btrfs_drop_extent_cache() to extent_map.cGravatar Filipe Manana 1-4/+4
The function btrfs_drop_extent_cache() doesn't really belong at file.c because what it does is drop a range of extent maps for a file range. It directly allocates and manipulates extent maps, by dropping, splitting and replacing them in an extent map tree, so it should be located at extent_map.c, where all manipulations of an extent map tree and its extent maps are supposed to be done. So move it out of file.c and into extent_map.c. Additionally do the following changes: 1) Rename it into btrfs_drop_extent_map_range(), as this makes it more clear about what it does. The term "cache" is a bit confusing as it's not widely used, "extent maps" or "extent mapping" is much more common; 2) Change its 'skip_pinned' argument from int to bool; 3) Turn several of its local variables from int to bool, since they are used as booleans; 4) Move the declaration of some variables out of the function's main scope and into the scopes where they are used; 5) Remove pointless assignment of false to 'modified' early in the while loop, as later that variable is set and it's not used before that second assignment; 6) Remove checks for NULL before calling free_extent_map(). Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>