[PATCH 2/5] xfs: use xfs_ilock_map_shared in xfs_qm_dqtobp

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

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@xxxxxx>

Index: xfs/fs/xfs/xfs_dquot.c
===================================================================
--- xfs.orig/fs/xfs/xfs_dquot.c 2013-11-18 14:39:01.955589999 +0100
+++ xfs/fs/xfs/xfs_dquot.c      2013-12-05 11:42:34.759679600 +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_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_map_shared(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_map_shared(quotip, lock_mode);
        if (error)
                return error;