linux-kernel - [PATCH 4.9 52/78] xfs: toggle readonly state around xfs_log_mount

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Message-Id: <20170918091134.207522464@linuxfoundation.org>
Date:   Mon, 18 Sep 2017 11:12:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Eric Sandeen <sandeen@...hat.com>,
        Brian Foster <bfoster@...hat.com>,
        Christoph Hellwig <hch@....de>,
        "Darrick J. Wong" <darrick.wong@...cle.com>
Subject: [PATCH 4.9 52/78] xfs: toggle readonly state around xfs_log_mount_finish

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Sandeen <sandeen@...deen.net>

commit 6f4a1eefdd0ad4561543270a7fceadabcca075dd upstream.

When we do log recovery on a readonly mount, unlinked inode
processing does not happen due to the readonly checks in
xfs_inactive(), which are trying to prevent any I/O on a
readonly mount.

This is misguided - we do I/O on readonly mounts all the time,
for consistency; for example, log recovery.  So do the same
RDONLY flag twiddling around xfs_log_mount_finish() as we
do around xfs_log_mount(), for the same reason.

This all cries out for a big rework but for now this is a
simple fix to an obvious problem.

Signed-off-by: Eric Sandeen <sandeen@...hat.com>
Reviewed-by: Brian Foster <bfoster@...hat.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/xfs/xfs_log.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -743,10 +743,14 @@ xfs_log_mount_finish(
 	struct xfs_mount	*mp)
 {
 	int	error = 0;
+	bool	readonly = (mp->m_flags & XFS_MOUNT_RDONLY);
 
 	if (mp->m_flags & XFS_MOUNT_NORECOVERY) {
 		ASSERT(mp->m_flags & XFS_MOUNT_RDONLY);
 		return 0;
+	} else if (readonly) {
+		/* Allow unlinked processing to proceed */
+		mp->m_flags &= ~XFS_MOUNT_RDONLY;
 	}
 
 	/*
@@ -764,6 +768,9 @@ xfs_log_mount_finish(
 		xfs_log_work_queue(mp);
 	mp->m_super->s_flags &= ~MS_ACTIVE;
 
+	if (readonly)
+		mp->m_flags |= XFS_MOUNT_RDONLY;
+
 	return error;
 }