XFS / Quota Bug in 2.6.17.x and 2.6.18x

XFS / Quota Bug in 2.6.17.x and 2.6.18x

[ProfiHost - Stefan Priebe]

Hello!

The crash only occurs if you use quota and an IDE Drive without barrier 
support.

The Problem is, that on a new mount of a root filesystem - the flag 
VFS_RDONLY is set - and so no barrier check is done before checking 
quota. With this patch barrier check is done always. The partition 
should not be mounted at that moment, so it could not be READ ONLY. For 
mount -o remount, rw or something like this - XFS uses another function 
where VFS_RDONLY is checked.

Error Message:
ns2 Wed Jul 26 14:22:58 2006 "I/O error in filesystem ("hda6") meta-data dev
hda6 block 0x23db5ab       ("xlog_iodone") error 5 buf count 1024"
ns2 Wed Jul 26 14:22:58 2006 "xfs_force_shutdown(hda6,0x2) called from line
959 of file fs/xfs/xfs_log.c.  Return address = 0xc0211535"
ns2 Wed Jul 26 14:22:58 2006 "Filesystem "hda6": Log I/O Error Detected.
Shutting down filesystem: hda6"
ns2 Wed Jul 26 14:22:58 2006 "Please umount the filesystem, and rectify the
problem(s)"
ns2 Wed Jul 26 14:22:58 2006 "xfs_force_shutdown(hda6,0x1) called from line
338 of file fs/xfs/xfs_rw.c.  Return address = 0xc0211535"
ns2 Wed Jul 26 14:22:58 2006 "xfs_force_shutdown(hda6,0x1) called from line
338 of file fs/xfs/xfs_rw.c.  Return address = 0xc0211535"

Patch:
--- fs/xfs/xfs_vfsops.c.orig    2006-07-27 14:22:25.185949750 +0200
+++ fs/xfs/xfs_vfsops.c 2006-07-27 14:22:28.246141000 +0200
@@ -523,7 +523,7 @@ xfs_mount(
         if (error)
                 goto error2;

-       if ((mp->m_flags & XFS_MOUNT_BARRIER) && !(vfsp->vfs_flag & 
VFS_RDONLY))
+       if (mp->m_flags & XFS_MOUNT_BARRIER)
                 xfs_mountfs_check_barriers(mp);

         error = XFS_IOINIT(vfsp, args, flags);

Best regards,
Stefan
Ihr ProfiHost Team
------------------------------------------
ProfiHost e.K.
Lindener Str 15
38300 Wolfenbüttel

Tel.: 05331 996890
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Re: XFS / Quota Bug in 2.6.17.x and 2.6.18x

[Nathan Scott]

Hi Stefan,

On Thu, Jul 27, 2006 at 01:39:29PM +0200, ProfiHost - Stefan Priebe wrote:
> Hello!
> 
> The crash only occurs if you use quota and IDE without barrier support.
> 
> The Problem is, that on a new mount of a root filesystem - the flag 
> VFS_RDONLY is set - and so no barrier check is done before checking 
> quota. With this patch barrier check is done always. The partition 
> should not be mounted at that moment. For mount -o remount, rw or 
> something like this it uses another function where VFS_RDONLY is checked.

Ah, I see.  The patch isn't quite right, I think we will now need to
also add a test to xfs_mountfs_check_barriers() to ensure the device
beneath us is not bdev_read_only().

I'll add that and get the fix merged, thanks.

cheers.

-- 
Nathan