gfs2: Flush delete work before shrinking inode cache

In gfs2_kill_sb(), flush the delete work queue after setting the
SDF_DEACTIVATING flag.  This ensures that no new inodes will be
instantiated anymore, and the inode cache will be empty after the
following kill_block_super() -> generic_shutdown_super() ->
evict_inodes() call.

With that, function gfs2_make_fs_ro() now calls gfs2_flush_delete_work()
after the workqueue has been destroyed.  Skip that by checking for the
presence of the SDF_DEACTIVATING flag.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

fs/gfs2/ops_fstype.c

@@ -1743,7 +1743,16 @@ static void gfs2_kill_sb(struct super_block *sb)
 	sdp->sd_root_dir = NULL;
 	sdp->sd_master_dir = NULL;
 	shrink_dcache_sb(sb);
+
+	/*
+	 * Flush and then drain the delete workqueue here (via
+	 * destroy_workqueue()) to ensure that any delete work that
+	 * may be running will also see the SDF_DEACTIVATING flag.
+	 */
 	set_bit(SDF_DEACTIVATING, &sdp->sd_flags);
+	gfs2_flush_delete_work(sdp);
+	destroy_workqueue(sdp->sd_delete_wq);
+
 	kill_block_super(sb);
 }
 

fs/gfs2/super.c

@@ -529,7 +529,9 @@ void gfs2_make_fs_ro(struct gfs2_sbd *sdp)
 {
 	int log_write_allowed = test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
 
-	gfs2_flush_delete_work(sdp);
+	if (!test_bit(SDF_DEACTIVATING, &sdp->sd_flags))
+		gfs2_flush_delete_work(sdp);
+
 	if (!log_write_allowed && current == sdp->sd_quotad_process)
 		fs_warn(sdp, "The quotad daemon is withdrawing.\n");
 	else if (sdp->sd_quotad_process)
@@ -630,8 +632,6 @@ restart:
 	/*  Unmount the locking protocol  */
 	gfs2_lm_unmount(sdp);
 
-	destroy_workqueue(sdp->sd_delete_wq);
-
 	/*  At this point, we're through participating in the lockspace  */
 	gfs2_sys_fs_del(sdp);
 	free_sbd(sdp);