[PATCH 5.15 729/779] btrfs: properly flag filesystem with BTRFS_FEATURE_INCOMPAT_BIG_METADATA

From: Greg Kroah-Hartman
Date: Mon Aug 15 2022 - 15:58:05 EST


From: Nikolay Borisov <nborisov@xxxxxxxx>

[ Upstream commit e26b04c4c91925dba57324db177a24e18e2d0013 ]

Commit 6f93e834fa7c seemingly inadvertently moved the code responsible
for flagging the filesystem as having BIG_METADATA to a place where
setting the flag was essentially lost. This means that
filesystems created with kernels containing this bug (starting with 5.15)
can potentially be mounted by older (pre-3.4) kernels. In reality
chances for this happening are low because there are other incompat
flags introduced in the mean time. Still the correct behavior is to set
INCOMPAT_BIG_METADATA flag and persist this in the superblock.

Fixes: 6f93e834fa7c ("btrfs: fix upper limit for max_inline for page size 64K")
CC: stable@xxxxxxxxxxxxxxx # 5.4+
Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>
Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/btrfs/disk-io.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 383e9c861306..e65c3039caf1 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3337,16 +3337,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
*/
fs_info->compress_type = BTRFS_COMPRESS_ZLIB;

- /*
- * Flag our filesystem as having big metadata blocks if they are bigger
- * than the page size.
- */
- if (btrfs_super_nodesize(disk_super) > PAGE_SIZE) {
- if (!(features & BTRFS_FEATURE_INCOMPAT_BIG_METADATA))
- btrfs_info(fs_info,
- "flagging fs with big metadata feature");
- features |= BTRFS_FEATURE_INCOMPAT_BIG_METADATA;
- }

/* Set up fs_info before parsing mount options */
nodesize = btrfs_super_nodesize(disk_super);
@@ -3387,6 +3377,17 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
if (features & BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA)
btrfs_info(fs_info, "has skinny extents");

+ /*
+ * Flag our filesystem as having big metadata blocks if they are bigger
+ * than the page size.
+ */
+ if (btrfs_super_nodesize(disk_super) > PAGE_SIZE) {
+ if (!(features & BTRFS_FEATURE_INCOMPAT_BIG_METADATA))
+ btrfs_info(fs_info,
+ "flagging fs with big metadata feature");
+ features |= BTRFS_FEATURE_INCOMPAT_BIG_METADATA;
+ }
+
/*
* mixed block groups end up with duplicate but slightly offset
* extent buffers for the same range. It leads to corruptions
--
2.35.1