diff options
| author | Omar Sandoval <osandov@fb.com> | 2016-09-22 17:24:22 -0700 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2016-10-03 18:52:14 +0200 |
| commit | 6675df311db87aa2107a04ef97e19420953cbace (patch) | |
| tree | 0c1afd7c2acb7bcb767c949984203c6f96ac4184 /include/uapi/linux | |
| parent | f8d468a15c22b954b379aa0c74914d5068448fb1 (diff) | |
Btrfs: catch invalid free space trees
There are two separate issues that can lead to corrupted free space
trees.
1. The free space tree bitmaps had an endianness issue on big-endian
systems which is fixed by an earlier patch in this series.
2. btrfs-progs before v4.7.3 modified filesystems without updating the
free space tree.
To catch both of these issues at once, we need to force the free space
tree to be rebuilt. To do so, add a FREE_SPACE_TREE_VALID compat_ro bit.
If the bit isn't set, we know that it was either produced by a broken
big-endian kernel or may have been corrupted by btrfs-progs.
This also provides us with a way to add rudimentary read-write support
for the free space tree to btrfs-progs: it can just clear this bit and
have the kernel rebuild the free space tree.
Cc: stable@vger.kernel.org # 4.5+
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'include/uapi/linux')
| -rw-r--r-- | include/uapi/linux/btrfs.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h index ac5eacd3055b..db4c253f8011 100644 --- a/include/uapi/linux/btrfs.h +++ b/include/uapi/linux/btrfs.h @@ -239,7 +239,17 @@ struct btrfs_ioctl_fs_info_args { * Used by: * struct btrfs_ioctl_feature_flags */ -#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE (1ULL << 0) +#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE (1ULL << 0) +/* + * Older kernels (< 4.9) on big-endian systems produced broken free space tree + * bitmaps, and btrfs-progs also used to corrupt the free space tree (versions + * < 4.7.3). If this bit is clear, then the free space tree cannot be trusted. + * btrfs-progs can also intentionally clear this bit to ask the kernel to + * rebuild the free space tree, however this might not work on older kernels + * that do not know about this bit. If not sure, clear the cache manually on + * first mount when booting older kernel versions. + */ +#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID (1ULL << 1) #define BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF (1ULL << 0) #define BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL (1ULL << 1) |