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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Carlos Maiolino <cmaiolino@redhat.com>,
        "Darrick J . Wong" <darrick.wong@oracle.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.14 089/100] xfs: Properly retry failed dquot
 items in case of error during buffer writeback
Thread-Topic: [PATCH AUTOSEL for 4.14 089/100] xfs: Properly retry failed
 dquot items in case of error during buffer writeback
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Date:   Wed, 24 Jan 2018 04:15:11 +0000
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From: Carlos Maiolino <cmaiolino@redhat.com>

[ Upstream commit 373b0589dc8d58bc09c9a28d03611ae4fb216057 ]

Once the inode item writeback errors is already fixed, it's time to fix the=
 same
problem in dquot code.

Although there were no reports of users hitting this bug in dquot code (at =
least
none I've seen), the bug is there and I was already planning to fix it when=
 the
correct approach to fix the inodes part was decided.

This patch aims to fix the same problem in dquot code, regarding failed buf=
fers
being unable to be resubmitted once they are flush locked.

Tested with the recently test-case sent to fstests list by Hou Tao.

Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 fs/xfs/xfs_dquot.c      | 14 +++++++++++---
 fs/xfs/xfs_dquot_item.c | 40 ++++++++++++++++++++++++++++++++++++++--
 2 files changed, 49 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index cd82429d8df7..5a86495127fd 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -987,14 +987,22 @@ xfs_qm_dqflush_done(
 	 * holding the lock before removing the dquot from the AIL.
 	 */
 	if ((lip->li_flags & XFS_LI_IN_AIL) &&
-	    lip->li_lsn =3D=3D qip->qli_flush_lsn) {
+	    ((lip->li_lsn =3D=3D qip->qli_flush_lsn) ||
+	     (lip->li_flags & XFS_LI_FAILED))) {
=20
 		/* xfs_trans_ail_delete() drops the AIL lock. */
 		spin_lock(&ailp->xa_lock);
-		if (lip->li_lsn =3D=3D qip->qli_flush_lsn)
+		if (lip->li_lsn =3D=3D qip->qli_flush_lsn) {
 			xfs_trans_ail_delete(ailp, lip, SHUTDOWN_CORRUPT_INCORE);
-		else
+		} else {
+			/*
+			 * Clear the failed state since we are about to drop the
+			 * flush lock
+			 */
+			if (lip->li_flags & XFS_LI_FAILED)
+				xfs_clear_li_failed(lip);
 			spin_unlock(&ailp->xa_lock);
+		}
 	}
=20
 	/*
diff --git a/fs/xfs/xfs_dquot_item.c b/fs/xfs/xfs_dquot_item.c
index 2c7a1629e064..664dea105e76 100644
--- a/fs/xfs/xfs_dquot_item.c
+++ b/fs/xfs/xfs_dquot_item.c
@@ -137,6 +137,26 @@ xfs_qm_dqunpin_wait(
 	wait_event(dqp->q_pinwait, (atomic_read(&dqp->q_pincount) =3D=3D 0));
 }
=20
+/*
+ * Callback used to mark a buffer with XFS_LI_FAILED when items in the buf=
fer
+ * have been failed during writeback
+ *
+ * this informs the AIL that the dquot is already flush locked on the next=
 push,
+ * and acquires a hold on the buffer to ensure that it isn't reclaimed bef=
ore
+ * dirty data makes it to disk.
+ */
+STATIC void
+xfs_dquot_item_error(
+	struct xfs_log_item	*lip,
+	struct xfs_buf		*bp)
+{
+	struct xfs_dquot	*dqp;
+
+	dqp =3D DQUOT_ITEM(lip)->qli_dquot;
+	ASSERT(!completion_done(&dqp->q_flush));
+	xfs_set_li_failed(lip, bp);
+}
+
 STATIC uint
 xfs_qm_dquot_logitem_push(
 	struct xfs_log_item	*lip,
@@ -144,13 +164,28 @@ xfs_qm_dquot_logitem_push(
 					      __acquires(&lip->li_ailp->xa_lock)
 {
 	struct xfs_dquot	*dqp =3D DQUOT_ITEM(lip)->qli_dquot;
-	struct xfs_buf		*bp =3D NULL;
+	struct xfs_buf		*bp =3D lip->li_buf;
 	uint			rval =3D XFS_ITEM_SUCCESS;
 	int			error;
=20
 	if (atomic_read(&dqp->q_pincount) > 0)
 		return XFS_ITEM_PINNED;
=20
+	/*
+	 * The buffer containing this item failed to be written back
+	 * previously. Resubmit the buffer for IO
+	 */
+	if (lip->li_flags & XFS_LI_FAILED) {
+		if (!xfs_buf_trylock(bp))
+			return XFS_ITEM_LOCKED;
+
+		if (!xfs_buf_resubmit_failed_buffers(bp, lip, buffer_list))
+			rval =3D XFS_ITEM_FLUSHING;
+
+		xfs_buf_unlock(bp);
+		return rval;
+	}
+
 	if (!xfs_dqlock_nowait(dqp))
 		return XFS_ITEM_LOCKED;
=20
@@ -242,7 +277,8 @@ static const struct xfs_item_ops xfs_dquot_item_ops =3D=
 {
 	.iop_unlock	=3D xfs_qm_dquot_logitem_unlock,
 	.iop_committed	=3D xfs_qm_dquot_logitem_committed,
 	.iop_push	=3D xfs_qm_dquot_logitem_push,
-	.iop_committing =3D xfs_qm_dquot_logitem_committing
+	.iop_committing =3D xfs_qm_dquot_logitem_committing,
+	.iop_error	=3D xfs_dquot_item_error
 };
=20
 /*
--=20
2.11.0