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author | Nikolay Borisov <nborisov@suse.com> | 2020-01-10 15:11:34 +0300 |
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committer | David Sterba <dsterba@suse.com> | 2020-01-23 19:24:38 +0300 |
commit | 05840710149c7d1a78ea85a2db5723f706e97d8f (patch) | |
tree | 926e216b113647bdc2a5126214718cc9312ef1c1 /fs/btrfs/volumes.c | |
parent | c6730a0e5778bf2d83189f97ab5e3efe61f6aad1 (diff) | |
download | linux-05840710149c7d1a78ea85a2db5723f706e97d8f.tar.xz |
btrfs: Handle another split brain scenario with metadata uuid feature
There is one more cases which isn't handled by the original metadata
uuid work. Namely, when a filesystem has METADATA_UUID incompat bit and
the user decides to change the FSID to the original one e.g. have
metadata_uuid and fsid match. In case of power failure while this
operation is in progress we could end up in a situation where some of
the disks have the incompat bit removed and the other half have both
METADATA_UUID_INCOMPAT and FSID_CHANGING_IN_PROGRESS flags.
This patch handles the case where a disk that has successfully changed
its FSID such that it equals METADATA_UUID is scanned first.
Subsequently when a disk with both
METADATA_UUID_INCOMPAT/FSID_CHANGING_IN_PROGRESS flags is scanned
find_fsid_changed won't be able to find an appropriate btrfs_fs_devices.
This is done by extending find_fsid_changed to correctly find
btrfs_fs_devices whose metadata_uuid/fsid are the same and they match
the metadata_uuid of the currently scanned device.
Fixes: cc5de4e70256 ("btrfs: Handle final split-brain possibility during fsid change")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reported-by: Su Yue <Damenly_Su@gmx.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/volumes.c')
-rw-r--r-- | fs/btrfs/volumes.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index d48274451452..7a30dd8ffdb5 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -710,17 +710,28 @@ static struct btrfs_fs_devices *find_fsid_changed( /* * Handles the case where scanned device is part of an fs that had * multiple successful changes of FSID but curently device didn't - * observe it. Meaning our fsid will be different than theirs. + * observe it. Meaning our fsid will be different than theirs. We need + * to handle two subcases : + * 1 - The fs still continues to have different METADATA/FSID uuids. + * 2 - The fs is switched back to its original FSID (METADATA/FSID + * are equal). */ list_for_each_entry(fs_devices, &fs_uuids, fs_list) { + /* Changed UUIDs */ if (memcmp(fs_devices->metadata_uuid, fs_devices->fsid, BTRFS_FSID_SIZE) != 0 && memcmp(fs_devices->metadata_uuid, disk_super->metadata_uuid, BTRFS_FSID_SIZE) == 0 && memcmp(fs_devices->fsid, disk_super->fsid, - BTRFS_FSID_SIZE) != 0) { + BTRFS_FSID_SIZE) != 0) + return fs_devices; + + /* Unchanged UUIDs */ + if (memcmp(fs_devices->metadata_uuid, fs_devices->fsid, + BTRFS_FSID_SIZE) == 0 && + memcmp(fs_devices->fsid, disk_super->metadata_uuid, + BTRFS_FSID_SIZE) == 0) return fs_devices; - } } return NULL; |