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From: Brian Foster <bfoster@redhat.com>
To: linux-xfs@vger.kernel.org
Subject: [PATCH 1/2] xfs: trylock underlying buffer on dquot flush
Date: Thu, 26 Mar 2020 09:17:02 -0400
Message-ID: <20200326131703.23246-2-bfoster@redhat.com> (raw)
In-Reply-To: <20200326131703.23246-1-bfoster@redhat.com>

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>
---
 fs/xfs/xfs_dquot.c      |  6 +++---
 fs/xfs/xfs_dquot_item.c |  3 ++-
 fs/xfs/xfs_qm.c         | 14 +++++++++-----
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 711376ca269f..af2c8e5ceea0 100644
--- 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 cf65e2e43c6e..baad1748d0d1 100644
--- 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 de1d2c606c14..68c778d25c48 100644
--- 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;
 }
 
 /*
-- 
2.21.1


  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-26 13:17 [PATCH 0/2] xfs: a couple AIL pushing trylock fixes Brian Foster
2020-03-26 13:17 ` Brian Foster [this message]
2020-03-27 12:59   ` [PATCH 1/2] xfs: trylock underlying buffer on dquot flush Christoph Hellwig
2020-03-27 15:45   ` Darrick J. Wong
2020-03-27 16:44     ` Brian Foster
2020-03-27 16:46       ` Brian Foster
2020-03-27 17:04         ` Darrick J. Wong
2020-03-27 16:50       ` Darrick J. Wong
2020-03-29 22:46   ` Dave Chinner
2020-03-29 23:01     ` Dave Chinner
2020-03-30 12:15     ` Brian Foster
2020-03-31  0:04       ` Dave Chinner
2020-03-31 11:46         ` Brian Foster
2020-03-26 13:17 ` [PATCH 2/2] xfs: return locked status of inode buffer on xfsaild push Brian Foster
2020-03-27 13:00   ` Christoph Hellwig
2020-03-27 15:39   ` Darrick J. Wong
2020-03-27 15:32 ` [PATCH 0/2] xfs: a couple AIL pushing trylock fixes Darrick J. Wong
2020-03-27 16:44   ` Brian Foster
2020-03-29 16:43     ` Darrick J. Wong

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