xfs: shutdown xfs_sync_worker before the log

Revert commit 1307bbd, which uses the s_umount semaphore to provide
exclusion between xfs_sync_worker and unmount, in favor of shutting down
the sync worker before freeing the log in xfs_log_unmount.  This is a
cleaner way of resolving the race between xfs_sync_worker and unmount
than using s_umount.

Signed-off-by: Ben Myers <bpm@sgi.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index f30d9807dc48a0535084da1afd5a7620389adcd5..0e1a64f0439ca5c3457bb7d360489f9ce3f027e2 100644 (file)
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -810,6 +810,7 @@ xfs_log_unmount_write(xfs_mount_t *mp)
 void
 xfs_log_unmount(xfs_mount_t *mp)
 {
+       cancel_delayed_work_sync(&mp->m_sync_work);
        xfs_trans_ail_destroy(mp);
        xlog_dealloc_log(mp->m_log);
 }

diff --git a/fs/xfs/xfs_sync.c b/fs/xfs/xfs_sync.c
index c9d3409c5ca3f991b7bde133994c4920316a216c..1e9ee064dbb28c7cb491d4c41dce53007eebc7e9 100644 (file)
--- a/fs/xfs/xfs_sync.c
+++ b/fs/xfs/xfs_sync.c
@@ -386,23 +386,23 @@ xfs_sync_worker(
         * We shouldn't write/force the log if we are in the mount/unmount
         * process or on a read only filesystem. The workqueue still needs to be
         * active in both cases, however, because it is used for inode reclaim
-        * during these times.  Use the s_umount semaphore to provide exclusion
-        * with unmount.
+        * during these times.  Use the MS_ACTIVE flag to avoid doing anything
+        * during mount.  Doing work during unmount is avoided by calling
+        * cancel_delayed_work_sync on this work queue before tearing down
+        * the ail and the log in xfs_log_unmount.
         */
-       if (down_read_trylock(&mp->m_super->s_umount)) {
-               if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
-                       /* dgc: errors ignored here */
-                       if (mp->m_super->s_frozen == SB_UNFROZEN &&
-                           xfs_log_need_covered(mp))
-                               error = xfs_fs_log_dummy(mp);
-                       else
-                               xfs_log_force(mp, 0);
-
-                       /* start pushing all the metadata that is currently
-                        * dirty */
-                       xfs_ail_push_all(mp->m_ail);
-               }
-               up_read(&mp->m_super->s_umount);
+       if (!(mp->m_super->s_flags & MS_ACTIVE) &&
+           !(mp->m_flags & XFS_MOUNT_RDONLY)) {
+               /* dgc: errors ignored here */
+               if (mp->m_super->s_frozen == SB_UNFROZEN &&
+                   xfs_log_need_covered(mp))
+                       error = xfs_fs_log_dummy(mp);
+               else
+                       xfs_log_force(mp, 0);
+
+               /* start pushing all the metadata that is currently
+                * dirty */
+               xfs_ail_push_all(mp->m_ail);
        }
 
        /* queue us up again */