is_seen_fsid() uses simple hash to check if FS was seen before at
walking on FS list in 'filesystem show' command: hash key is first byte
of the UUID. This function doesn't check full UUID then, so, if there
are two FS with same first byte in UUIDs exist, only one will be shown:
root@test:~# btrfs fi show
Label: 'System' uuid: 688cb918-7bac-4c8e-9b11-8d047eb14cf4
Total devices 2 FS bytes used 1.76GiB
devid 1 size 3.46TiB used 4.01GiB path /dev/sda2
devid 2 size 6.91TiB used 4.01GiB path /dev/sdb2
Global spare
root@test:~# grep btrfs /proc/mounts
/dev/sda2 / btrfs rw,relatime,space_cache,subvolid=256,subvol=/root 0 0
/dev/sdc /media/688cb918-7bac-4c8e-9b11-8d047eb14cf4 btrfs rw,relatime,space_cache,subvolid=5,subvol=/ 0 0
root@test:~# btrfs fi show --all-devices
Label: 'System' uuid: 688cb918-7bac-4c8e-9b11-8d047eb14cf4
Total devices 2 FS bytes used 1.76GiB
devid 1 size 3.46TiB used 4.03GiB path /dev/sda2
devid 2 size 6.91TiB used 4.01GiB path /dev/sdb2
Label: 'test' uuid: 683b1a80-ca7f-4c4d-b87b-7155401a4d18
Total devices 7 FS bytes used 2.06MiB
devid 1 size 7.28TiB used 1.57GiB path /dev/sdc
devid 2 size 7.28TiB used 1.57GiB path /dev/sdd
devid 3 size 7.28TiB used 1.57GiB path /dev/sde
devid 4 size 7.28TiB used 1.57GiB path /dev/sdf
devid 5 size 7.28TiB used 1.57GiB path /dev/sdg
devid 6 size 7.28TiB used 1.57GiB path /dev/sdh
devid 7 size 7.28TiB used 1.57GiB path /dev/sdi
To resolve this collision, search for full FSID in the list of seen
filesystems.
Signed-off-by: Yauhen Kharuzhy <yauhen.kharuzhy@xxxxxxxxxxxxx>
---
cmds-filesystem.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/cmds-filesystem.c b/cmds-filesystem.c
index f8fc764..97b2645 100644
--- a/cmds-filesystem.c
+++ b/cmds-filesystem.c
@@ -58,7 +58,14 @@ static int is_seen_fsid(u8 *fsid)
int slot = hash % SEEN_FSID_HASH_SIZE;
struct seen_fsid *seen = seen_fsid_hash[slot];
- return seen ? 1 : 0;
+ while (seen) {
+ if (memcmp(seen->fsid, fsid, BTRFS_FSID_SIZE) == 0)
+ return 1;
+
+ seen = seen->next;
+ }
+
+ return 0;
}
static int add_seen_fsid(u8 *fsid)
--
2.5.0
--
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