Re: [PATCH 07/11] xfs: use xfs_ilock_data_map_shared in xfs_qm_dqtobp

Dave Chinner
2013-12-08T22:38:30Z

On Fri, Dec 06, 2013 at 12:30:13PM -0800, Christoph Hellwig wrote:
> We might not have read in the extent list at this point, so make sure we
> take the ilock exclusively if we have to do so.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
>
> Index: xfs/fs/xfs/xfs_dquot.c
> ===================================================================
> --- xfs.orig/fs/xfs/xfs_dquot.c 2013-12-06 17:20:27.571331599 +0100
> +++ xfs/fs/xfs/xfs_dquot.c 2013-12-06 19:39:42.307160146 +0100
> @@ -469,16 +469,17 @@ xfs_qm_dqtobp(
> struct xfs_mount *mp = dqp->q_mount;
> xfs_dqid_t id = be32_to_cpu(dqp->q_core.d_id);
> struct xfs_trans *tp = (tpp ? *tpp : NULL);
> + uint lock_mode;
>
> dqp->q_fileoffset = (xfs_fileoff_t)id / mp->m_quotainfo->qi_dqperchunk;
>
> - xfs_ilock(quotip, XFS_ILOCK_SHARED);
> + lock_mode = xfs_ilock_data_map_shared(quotip);
> if (!xfs_this_quota_on(dqp->q_mount, dqp->dq_flags)) {
> /*
> * Return if this type of quotas is turned off while we
> * didn't have the quota inode lock.
> */
> - xfs_iunlock(quotip, XFS_ILOCK_SHARED);
> + xfs_iunlock(quotip, lock_mode);
> return ESRCH;
> }
>
> @@ -488,7 +489,7 @@ xfs_qm_dqtobp(
> error = xfs_bmapi_read(quotip, dqp->q_fileoffset,
> XFS_DQUOT_CLUSTER_SIZE_FSB, &map, &nmaps, 0);
>
> - xfs_iunlock(quotip, XFS_ILOCK_SHARED);
> + xfs_iunlock(quotip, lock_mode);
> if (error)
> return error;

Looks fine - it doesn't change the race condition w/ dquot creation
at all, so we can ignore that for now...

Reviewed-by: Dave Chinner <dchinner@redhat.com>

--
Dave Chinner
david@fromorbit.com