On 04/29/2013 10:51 PM, Mark Tinguely wrote:
> On 04/29/13 06:44, Jeff Liu wrote:
>> From: Jie Liu<jeff.liu@xxxxxxxxxx>
>>
>> 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 will be silently ignored, so it's better to tell user
>> that the alignment-changing can not take affect in one way or another.
>>
>> With this fix, the attempt to mount a storage without strip alignment
>> setup on super block will failed if XFS_MOUNT_RETERR is enabled, or
>> just ignore the given alignment and drop a warning to indicate the
>> cause in syslog.
>>
>> # 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: no data alignment on superblock
>>
>> Signed-off-by: Jie Liu<jeff.liu@xxxxxxxxxx>
>>
>> ---
>> fs/xfs/xfs_mount.c | 7 +++++++
>> 1 file changed, 7 insertions(+)
>>
>> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
>> index 3806088..bc7fdd4 100644
>> --- a/fs/xfs/xfs_mount.c
>> +++ b/fs/xfs/xfs_mount.c
>> @@ -924,6 +924,13 @@ xfs_update_alignment(xfs_mount_t *mp)
>> sbp->sb_width = mp->m_swidth;
>> mp->m_update_flags |= XFS_SB_WIDTH;
>> }
>> + } else {
>> + xfs_warn(mp, "can not change alignment: "
>> + "no data alignment on superblock");
> suggest that you keep the string together so it can be searched.
> "superblock does not support data alignment"
Do you means that the string would shown as: "superblock does not
support data alignment"?
Or "cannot change alignment: superblock does not support data alignment"?
I prefer to the later format because it can distinguish this special
case from the previous alignment validation procedure, i.e,
"alignment check failed: xxx".
Thanks,
-Jeff
>
>> + if (mp->m_flags& XFS_MOUNT_RETERR)
>> + return XFS_ERROR(EINVAL);
>> + mp->m_dalign = 0;
>> + mp->m_swidth = 0;
>> }
>> } else if ((mp->m_flags& XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN&&
>> xfs_sb_version_hasdalign(&mp->m_sb)) {
>
>
> Thanks,
>
> --Mark.
>
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