btrfs: properly flag filesystem with BTRFS_FEATURE_INCOMPAT_BIG_METADATA

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@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 243bd7b..e12fd3a 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3484,16 +3484,6 @@ 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);
@@ -3534,6 +3524,17 @@ 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