[PATCH v3 2/2] xfs: Don't keep silent if sunit/swidth can not be changed via mount

[PATCH v3 2/2] xfs: Don't keep silent if sunit/swidth can not be changed via mount

[Jeff Liu]

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, e.g.
# 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
.......
XFS (sdb1): cannot 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 95bd4b5..d243ab7 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");
+			return XFS_ERROR(EINVAL);
 		}
 	} else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
 		    xfs_sb_version_hasdalign(&mp->m_sb)) {
-- 
1.7.9.5

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Re: [PATCH v3 2/2] xfs: Don't keep silent if sunit/swidth can not be changed via mount

[Mark Tinguely]

On 05/02/13 06:27, 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, e.g.
> # 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
> .......
> XFS (sdb1): cannot change alignment: superblock does not support data
> alignment
>
> Signed-off-by: Jie Liu<jeff.liu@oracle.com>

Looks good.

Reviewed-by: Mark Tinguely <tinguely@sgi.com>

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Re: [PATCH v3 2/2] xfs: Don't keep silent if sunit/swidth can not be changed via mount

[Ben Myers]

On Thu, May 02, 2013 at 07:27:53PM +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, e.g.
> # 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
> .......
> XFS (sdb1): cannot 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>

Applied.

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