[PATCH v5] Stop xfs_do_force_shutdown / messages fron xfs_log_force if filesystem is already shutdown.

[raghu.prabhu13 at gmail.com]

From: Raghavendra D Prabhu <rprabhu at wnohang.net>

This is to prevent xfs_log_force from printing error message continuously (due
to xfs_sync and others) till umount if the disk has been forcefully unplugged.

This is to prevent messages like these from being displayed repeatedly.

[ 3873.009329] XFS (sdb3): xfs_log_force: error 5 returned.

Note, that even after xfs_do_force_shutdown has been called, xfs_log_force
doesn't stop till the filesystem has been unmounted (and it keeps printing
"error 5 returned" to kernel log). Also, xfs_do_force_shutdown is called
repeatedly on an already shutdown filesystem through xfs_fs_sync_fs.

To fix this, added condition over XFS_FORCED_SHUTDOWN to xfs_log_force and
xfs_fs_sync_fs.

To simulate it, mount an xfs filesystem located on external disk, and then pull
the power to the disk.

Now, the dmesg looks,

[  268.307303] XFS (sdb2): xfs_do_force_shutdown(0x1) called from line 1031 of file fs/xfs/xfs_buf.c.  Return address = 0xffffffff8127c13a
[  268.307318] XFS (sdb2): I/O Error Detected. Shutting down filesystem
[  268.307323] XFS (sdb2): Please umount the filesystem and rectify the problem(s)

---

Version 1: Removed calling xfs_syncd_stop from xfs_sync_worker.
Version 2: Removed calling xfs_fs_writable in xfs_sync_worker and xfs_flush_worker.
Version 3: Removed calling xfs_syncd_stop in xfs_bwrite.
Version 4: Added return statements to xfs_log_force and xfs_fs_sync_fs.
Version 5: As per suggestion, added xfs_warn to xfs_fs_sync_fs and removed EIO
return in xfs_log_force

 Signed-off-by: Raghavendra D Prabhu <rprabhu at wnohang.net>
 Tested-by: Raghavendra D Prabhu <rprabhu at wnohang.net>
---
 fs/xfs/xfs_log.c   | 5 ++++-
 fs/xfs/xfs_super.c | 5 +++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 7f4f937..161c925 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -3002,7 +3002,10 @@ xfs_log_force(
 
 	trace_xfs_log_force(mp, 0);
 	error = _xfs_log_force(mp, flags, NULL);
-	if (error)
+	/*
+	 * Avoid warning when the filesystem has already shutdown.
+	 */
+	if (error && !XFS_FORCED_SHUTDOWN(mp))
 		xfs_warn(mp, "%s: error %d returned.", __func__, error);
 }
 
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index bdaf4cb..ebafc99 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -943,6 +943,11 @@ xfs_fs_sync_fs(
 	if (!wait)
 		return 0;
 
+	if (XFS_FORCED_SHUTDOWN(mp)) {
+		xfs_warn(mp, "Sync called: filesystem already shutdown");
+		return XFS_ERROR(EIO);
+	}
+
 	error = xfs_quiesce_data(mp);
 	if (error)
 		return -error;
-- 
1.7.12