Hi,
I've been getting the error message "fs tree 264 refs 1 not found" when
running btrfsck (v0.19) after a test case. The test case creates and
then deletes a subvolume while concurrently creating a snapshot of the
parent directory. This situation occurred with kernel version 3.11.1.
Here's one of the interleavings that triggers the "not found" message:
CPU: 0 Op: write
CPU: 1 Op: btrfs_subvol_delete ("d16", fail)
CPU: 1 Op: write
CPU: 1 Op: btrfs_subvol_create ("d16/d13b", success)
CPU: 0 Op: btrfs_subvol_snapshot ("d16" to
"d16/d21/d6d/d74/d101/d13d", success)
CPU: 1 Op: link
CPU: 1 Op: creat
CPU: 1 Op: btrfs_subvol_delete ("d16/d13b", success)
CPU: 1 Op: read
CPU: 0 Op: dread
CPU: 0 Op: creat
Another example that also triggered the message:
CPU: 0 Op: dread
CPU: 0 Op: write
CPU: 0 Op: btrfs_subvol_snapshot ("d16" to
"d16/d21/d6d/d74/d101/d13d", success)
CPU: 1 Op: btrfs_subvol_delete ("d16", fail)
CPU: 1 Op: write
CPU: 1 Op: btrfs_subvol_create ("d16/d13b", success)
CPU: 0 Op: dread
CPU: 0 Op: creat
CPU: 1 Op: link
CPU: 1 Op: creat
CPU: 1 Op: btrfs_subvol_delete ("d16/d13b", success)
CPU: 1 Op: read
In this case, "btrfs_subvol_snapshot" overlapped with the
"btrfs_subvol_create" operation but it did not overlap with the second
"btrfs_subvol_delete".
Btrfsck output (after unmounting the FS):
fs tree 257 refs 5
unresolved ref root 258 dir 256 index 10 namelen 3 name d21
error 600
unresolved ref root 262 dir 256 index 10 namelen 3 name d21
error 600
unresolved ref root 263 dir 256 index 10 namelen 3 name d21
error 600
unresolved ref root 265 dir 256 index 10 namelen 3 name d21
error 600
fs tree 262 refs 3
unresolved ref root 263 dir 256 index 39 namelen 3 name da6
error 600
unresolved ref root 265 dir 256 index 39 namelen 3 name da6
error 600
fs tree 263 refs 2
unresolved ref root 265 dir 256 index 43 namelen 3 name dce
error 600
fs tree 264 refs 1 not found
unresolved ref root 265 dir 256 index 56 namelen 4 name d13b
error 600
found 9924608 bytes used err is 1
total csum bytes: 9208
total tree bytes: 495616
total fs tree bytes: 417792
btree space waste bytes: 153475
file data blocks allocated: 12365824
referenced 11440128
btrfsck: Btrfs Btrfs v0.19
Let me know if you need more information.
Pedro
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