From: Qu Wenruo wqu@suse.com
commit 50e31ef486afe60f128d42fb9620e2a63172c15c upstream.
[BUG] There are several bug reports about recent kernel unable to relocate certain data block groups.
Sometimes the error just goes away, but there is one reporter who can reproduce it reliably.
The dmesg would look like:
[438.260483] BTRFS info (device dm-10): balance: start -dvrange=34625344765952..34625344765953 [438.269018] BTRFS info (device dm-10): relocating block group 34625344765952 flags data|raid1 [450.439609] BTRFS info (device dm-10): found 167 extents, stage: move data extents [463.501781] BTRFS info (device dm-10): balance: ended with status: -2
[CAUSE] The ENOENT error is returned from the following call chain:
add_data_references() |- delete_v1_space_cache(); |- if (!found) return -ENOENT;
The variable @found is set to true if we find a data extent whose disk bytenr matches parameter @data_bytes.
With extra debugging, the offending tree block looks like this:
leaf bytenr = 42676709441536, data_bytenr = 34626327621632
ctime 1567904822.739884119 (2019-09-08 03:07:02) mtime 0.0 (1970-01-01 01:00:00) otime 0.0 (1970-01-01 01:00:00) item 27 key (51933 EXTENT_DATA 0) itemoff 9854 itemsize 53 generation 1517381 type 2 (prealloc) prealloc data disk byte 34626327621632 nr 262144 <<< prealloc data offset 0 nr 262144 item 28 key (52262 ROOT_ITEM 0) itemoff 9415 itemsize 439 generation 2618893 root_dirid 256 bytenr 42677048360960 level 3 refs 1 lastsnap 2618893 byte_limit 0 bytes_used 5557338112 flags 0x0(none) uuid d0d4361f-d231-6d40-8901-fe506e4b2b53
Although item 27 has disk bytenr 34626327621632, which matches the data_bytenr, its type is prealloc, not reg. This makes the existing code skip that item, and return ENOENT.
[FIX] The code is modified in commit 19b546d7a1b2 ("btrfs: relocation: Use btrfs_find_all_leafs to locate data extent parent tree leaves"), before that commit, we use something like
"if (type == BTRFS_FILE_EXTENT_INLINE) continue;"
But in that offending commit, we use (type == BTRFS_FILE_EXTENT_REG), ignoring BTRFS_FILE_EXTENT_PREALLOC.
Fix it by also checking BTRFS_FILE_EXTENT_PREALLOC.
Reported-by: Stéphane Lesimple stephane_btrfs2@lesimple.fr Link: https://lore.kernel.org/linux-btrfs/505cabfa88575ed6dbe7cb922d8914fb@lesimpl... Fixes: 19b546d7a1b2 ("btrfs: relocation: Use btrfs_find_all_leafs to locate data extent parent tree leaves") CC: stable@vger.kernel.org # 5.6+ Tested-By: Stéphane Lesimple stephane_btrfs2@lesimple.fr Reviewed-by: Su Yue l@damenly.su Signed-off-by: Qu Wenruo wqu@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/relocation.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -3027,11 +3027,16 @@ static int delete_v1_space_cache(struct return 0;
for (i = 0; i < btrfs_header_nritems(leaf); i++) { + u8 type; + btrfs_item_key_to_cpu(leaf, &key, i); if (key.type != BTRFS_EXTENT_DATA_KEY) continue; ei = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item); - if (btrfs_file_extent_type(leaf, ei) == BTRFS_FILE_EXTENT_REG && + type = btrfs_file_extent_type(leaf, ei); + + if ((type == BTRFS_FILE_EXTENT_REG || + type == BTRFS_FILE_EXTENT_PREALLOC) && btrfs_file_extent_disk_bytenr(leaf, ei) == data_bytenr) { found = true; space_cache_ino = key.objectid;