From ec947125fcb7cb1aded3ab608b9a9255a433d256 Mon Sep 17 00:00:00 2001
From: Dave Chinner <dchinner@redhat.com>
Date: Mon, 8 Oct 2012 21:56:03 +1100
Subject: [PATCH] --- yaml --- r: 339375 b: refs/heads/master c:
 cf2931db2d189ce0583be7ae880d7e3f8c15f623 h: refs/heads/master i:   339373:
 6f29acfd4abbba3ea597e64c95de193b60126641   339371:
 97d398bb3f9eae853dd0b6d341685e73bbf65393   339367:
 742b4cf7c0159a60de75527568a8955bef5ddb64   339359:
 674ebc62930dd5fbb99935ce9185f33e17ca220e v: v3

---
 [refs]                   |  2 +-
 trunk/fs/xfs/xfs_log.c   | 29 ++++++++++++++++++++++++++---
 trunk/fs/xfs/xfs_mount.c | 24 ------------------------
 3 files changed, 27 insertions(+), 28 deletions(-)

diff --git a/[refs] b/[refs]
index a16d454074c5..ddd18973f97e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f661f1e0bf5002bdcc8b5810ad0a184a1841537f
+refs/heads/master: cf2931db2d189ce0583be7ae880d7e3f8c15f623
diff --git a/trunk/fs/xfs/xfs_log.c b/trunk/fs/xfs/xfs_log.c
index efea12bfbd6b..e788f39721e3 100644
--- a/trunk/fs/xfs/xfs_log.c
+++ b/trunk/fs/xfs/xfs_log.c
@@ -855,15 +855,38 @@ xfs_log_unmount_write(xfs_mount_t *mp)
 }	/* xfs_log_unmount_write */
 
 /*
- * Deallocate log structures for unmount/relocation.
+ * Shut down and release the AIL and Log.
  *
- * We need to stop the aild from running before we destroy
- * and deallocate the log as the aild references the log.
+ * During unmount, we need to ensure we flush all the dirty metadata objects
+ * from the AIL so that the log is empty before we write the unmount record to
+ * the log.
+ *
+ * To do this, we first need to shut down the background log work so it is not
+ * trying to cover the log as we clean up. We then need to unpin all objects in
+ * the log so we can then flush them out. Once they have completed their IO and
+ * run the callbacks removing themselves from the AIL, we can write the unmount
+ * record, tear down the AIL and finally free the log.
  */
 void
 xfs_log_unmount(xfs_mount_t *mp)
 {
 	cancel_delayed_work_sync(&mp->m_log->l_work);
+	xfs_log_force(mp, XFS_LOG_SYNC);
+
+	/*
+	 * The superblock buffer is uncached and while xfs_ail_push_all_sync()
+	 * will push it, xfs_wait_buftarg() will not wait for it. Further,
+	 * xfs_buf_iowait() cannot be used because it was pushed with the
+	 * XBF_ASYNC flag set, so we need to use a lock/unlock pair to wait for
+	 * the IO to complete.
+	 */
+	xfs_ail_push_all_sync(mp->m_ail);
+	xfs_wait_buftarg(mp->m_ddev_targp);
+	xfs_buf_lock(mp->m_sb_bp);
+	xfs_buf_unlock(mp->m_sb_bp);
+
+	xfs_log_unmount_write(mp);
+
 	xfs_trans_ail_destroy(mp);
 	xlog_dealloc_log(mp->m_log);
 }
diff --git a/trunk/fs/xfs/xfs_mount.c b/trunk/fs/xfs/xfs_mount.c
index d9a31c6a0c53..c195ec85c725 100644
--- a/trunk/fs/xfs/xfs_mount.c
+++ b/trunk/fs/xfs/xfs_mount.c
@@ -1459,13 +1459,6 @@ xfs_unmountfs(
 
 	xfs_qm_unmount(mp);
 
-	/*
-	 * Flush out the log synchronously so that we know for sure
-	 * that nothing is pinned.  This is important because bflush()
-	 * will skip pinned buffers.
-	 */
-	xfs_log_force(mp, XFS_LOG_SYNC);
-
 	/*
 	 * Unreserve any blocks we have so that when we unmount we don't account
 	 * the reserved free space as used. This is really only necessary for
@@ -1491,23 +1484,6 @@ xfs_unmountfs(
 		xfs_warn(mp, "Unable to update superblock counters. "
 				"Freespace may not be correct on next mount.");
 
-	/*
-	 * At this point we might have modified the superblock again and thus
-	 * added an item to the AIL, thus flush it again.
-	 */
-	xfs_ail_push_all_sync(mp->m_ail);
-	xfs_wait_buftarg(mp->m_ddev_targp);
-
-	/*
-	 * The superblock buffer is uncached and xfsaild_push() will lock and
-	 * set the XBF_ASYNC flag on the buffer. We cannot do xfs_buf_iowait()
-	 * here but a lock on the superblock buffer will block until iodone()
-	 * has completed.
-	 */
-	xfs_buf_lock(mp->m_sb_bp);
-	xfs_buf_unlock(mp->m_sb_bp);
-
-	xfs_log_unmount_write(mp);
 	xfs_log_unmount(mp);
 	xfs_uuid_unmount(mp);