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authorMark Tinguely <tinguely@sgi.com>2012-07-24 19:59:19 +0400
committerBen Myers <bpm@sgi.com>2012-07-30 01:34:19 +0400
commit9a57fa8ee7c29e11c2a29ce058573ba99157eda7 (patch)
tree3fc564a3ad53b16a6604aa89ae3d4d26e07e2d38
parent8375f922aaa6e7a880022529202fb486315568c3 (diff)
downloadlinux-9a57fa8ee7c29e11c2a29ce058573ba99157eda7.tar.xz
xfs: wait for the write the superblock on unmount
v2: Add the xfs_buf_lock to xfs_quiesce_attr(). Add explaination why xfs_buf_lock() is used to wait for write. xfs_wait_buftarg() does not wait for the completion of the write of the uncached superblock. This write can race with the shutdown of the log and causes a panic if the write does not win the race. During the log write, xfsaild_push() will lock the buffer and set the XBF_ASYNC flag. Because the XBF_FLAG is set, complete() is not performed on the buffer's iowait entry, we cannot call xfs_buf_iowait() to wait for the write to complete. The buffer's lock is held until the write is complete, so we can block on a xfs_buf_lock() request to be notified that the write is complete. Signed-off-by: Mark Tinguely <tinguely@sgi.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ben Myers <bpm@sgi.com>
-rw-r--r--fs/xfs/xfs_mount.c9
-rw-r--r--fs/xfs/xfs_sync.c9
2 files changed, 18 insertions, 0 deletions
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 9536fd190191..711ca51ca3d7 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1529,6 +1529,15 @@ xfs_unmountfs(
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);
diff --git a/fs/xfs/xfs_sync.c b/fs/xfs/xfs_sync.c
index e61fc1519073..97304f10e78a 100644
--- a/fs/xfs/xfs_sync.c
+++ b/fs/xfs/xfs_sync.c
@@ -359,6 +359,15 @@ xfs_quiesce_attr(
* added an item to the AIL, thus flush it again.
*/
xfs_ail_push_all_sync(mp->m_ail);
+
+ /*
+ * 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);
}
static void