Re: [PATCH 2/2 v2] xfs: Don't keep silent if sunit/swidth can not be changed via mount

Dave Chinner
2013-05-02T01:13:09Z

On Wed, May 01, 2013 at 10:25:19PM +0800, Jeff Liu wrote:
> From: Jie Liu <jeff.liu@oracle.com>
>
> As per the mount man page, sunit and swidth can be changed via
> mount options. For XFS, on the face of it, those options seems
> works if the specified alignments is properly, e.g.
> # mount -o sunit=4096,swidth=8192 /dev/sdb1 /mnt
> # mount | grep sdb1
> /dev/sdb1 on /mnt type xfs (rw,sunit=4096,swidth=8192)
>
> However, neither sunit nor swidth is shown from the xfs_info output.
> # xfs_info /mnt
> meta-data=/dev/sdb1 isize=256 agcount=4, agsize=262144 blks
> = sectsz=512 attr=2
> data = bsize=4096 blocks=1048576, imaxpct=25
> = sunit=0 swidth=0 blks
> ^^^^^^^^^^^^^^^^^^^^^^^^^^
> naming =version 2 bsize=4096 ascii-ci=0
> log =internal bsize=4096 blocks=2560, version=2
> = sectsz=512 sunit=0 blks, lazy-count=1
> realtime =none extsz=4096 blocks=0, rtextents=0
>
> The reason is that the alignment can only be changed if the relevant
> super block is already configured with alignments, otherwise, the
> given value is silently ignored.
>
> With this fix, the attempt to mount a storage without strip alignment
> setup on a super block will get an error with a warning in syslog to
> indicate the true cause.
>
> # mount -o sunit=4096,swidth=8192 /dev/sdb1 /mnt
> mount: wrong fs type, bad option, bad superblock on /dev/sdb1,
> missing codepage or helper program, or other error
> In some cases useful info is found in syslog - try
> dmesg | tail or so
> # dmesg|tail
> .......
> XFS (sdb1): can not change alignment: superblock does not support data
> alignment
>
> Signed-off-by: Jie Liu <jeff.liu@oracle.com>
> Cc: Mark Tinguely <tinguely@sgi.com>
> Cc: Dave Chinner <dchinner@redhat.com>
> ---
> fs/xfs/xfs_mount.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index 29e8de8..2836ef6 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -909,6 +909,10 @@ xfs_update_alignment(xfs_mount_t *mp)
> sbp->sb_width = mp->m_swidth;
> mp->m_update_flags |= XFS_SB_WIDTH;
> }
> + } else {
> + xfs_warn(mp, "cannot change alignment: "
> + "superblock does not support data alignment");

Same comment again about single line format strings. Otherwise it's
ok.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com