xfs: trylock underlying buffer on dquot flush

A dquot flush currently blocks on the buffer lock for the underlying
dquot buffer. In turn, this causes xfsaild to block rather than
continue processing other items in the meantime. Update
xfs_qm_dqflush() to trylock the buffer, similar to how inode buffers
are handled, and return -EAGAIN if the lock fails. Fix up any
callers that don't currently handle the error properly.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 711376c..af2c8e5 100644 (file)
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -1105,8 +1105,8 @@ xfs_qm_dqflush(
         * Get the buffer containing the on-disk dquot
         */
        error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp, dqp->q_blkno,
-                                  mp->m_quotainfo->qi_dqchunklen, 0, &bp,
-                                  &xfs_dquot_buf_ops);
+                                  mp->m_quotainfo->qi_dqchunklen, XBF_TRYLOCK,
+                                  &bp, &xfs_dquot_buf_ops);
        if (error)
                goto out_unlock;
 
@@ -1177,7 +1177,7 @@ xfs_qm_dqflush(
 
 out_unlock:
        xfs_dqfunlock(dqp);
-       return -EIO;
+       return error;
 }
 
 /*

diff --git a/fs/xfs/xfs_dquot_item.c b/fs/xfs/xfs_dquot_item.c
index cf65e2e..baad174 100644 (file)
--- a/fs/xfs/xfs_dquot_item.c
+++ b/fs/xfs/xfs_dquot_item.c
@@ -189,7 +189,8 @@ xfs_qm_dquot_logitem_push(
                if (!xfs_buf_delwri_queue(bp, buffer_list))
                        rval = XFS_ITEM_FLUSHING;
                xfs_buf_relse(bp);
-       }
+       } else if (error == -EAGAIN)
+               rval = XFS_ITEM_LOCKED;
 
        spin_lock(&lip->li_ailp->ail_lock);
 out_unlock:

diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index cabdb75..c225691 100644 (file)
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -121,12 +121,11 @@ xfs_qm_dqpurge(
 {
        struct xfs_mount        *mp = dqp->q_mount;
        struct xfs_quotainfo    *qi = mp->m_quotainfo;
+       int                     error = -EAGAIN;
 
        xfs_dqlock(dqp);
-       if ((dqp->dq_flags & XFS_DQ_FREEING) || dqp->q_nrefs != 0) {
-               xfs_dqunlock(dqp);
-               return -EAGAIN;
-       }
+       if ((dqp->dq_flags & XFS_DQ_FREEING) || dqp->q_nrefs != 0)
+               goto out_unlock;
 
        dqp->dq_flags |= XFS_DQ_FREEING;
 
@@ -139,7 +138,6 @@ xfs_qm_dqpurge(
         */
        if (XFS_DQ_IS_DIRTY(dqp)) {
                struct xfs_buf  *bp = NULL;
-               int             error;
 
                /*
                 * We don't care about getting disk errors here. We need
@@ -149,6 +147,8 @@ xfs_qm_dqpurge(
                if (!error) {
                        error = xfs_bwrite(bp);
                        xfs_buf_relse(bp);
+               } else if (error == -EAGAIN) {
+                       goto out_unlock;
                }
                xfs_dqflock(dqp);
        }
@@ -174,6 +174,10 @@ xfs_qm_dqpurge(
 
        xfs_qm_dqdestroy(dqp);
        return 0;
+
+out_unlock:
+       xfs_dqunlock(dqp);
+       return error;
 }
 
 /*