[dm-devel] Announce: unlimited number of shared snapshots

[Christoph Hellwig]

On Tue, Dec 02, 2008 at 02:05:28AM -0500, Mikulas Patocka wrote:
> Hi
> 
> I fixed the ext2 bug (it was unsupported handling of buffer readahead) --- 
> download the new version of patches from the same location.
> 
> I couldn't reproduce the XFS bug. Please retry. Are you sure that you 
> didn't try to mount the _snapshot_ as XFS? Snapshots are currently not 
> writeable (they will be writeable in the final version), so attempting to 
> mount the snapshot read/write would return i/o error to the filesystem and 
> produce an error message similar to the one displayed.

The error message definitively looks like trying to mount a r/o snapshots
without -o ro,norecovery:

> > fs/xfs/xfs_rw.c.  Return address = 0xffffffff8037d399
> > [ 2696.363710] Filesystem "dm-3": I/O Error Detected.  Shutting down
> > filesystem: dm-3
> > [ 2696.368085] Please umount the filesystem, and rectify the problem(s)
> > [ 2696.371756] I/O error in filesystem ("dm-3") meta-data dev dm-3 block
> > 0x200022       ("xlog_bwrite") error 5 buf count 2097152
> > [ 2696.378402] XFS: failed to locate log tail
> > [ 2696.380797] XFS: log mount/recovery failed: error 5
> > [ 2696.405586] XFS: log mount failed