async: Don't call async_synchronize_full_special() while holding sb_lock

sync_filesystems() shouldn't be calling async_synchronize_full_special
while holding a spinlock.  The second while loop in that function is the
right place for this anyway.
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Reported-by: Grissiom <chaos.proton@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/super.c

@@ -458,7 +458,6 @@ void sync_filesystems(int wait)
 		if (sb->s_flags & MS_RDONLY)
 			continue;
 		sb->s_need_sync_fs = 1;
-		async_synchronize_full_special(&sb->s_async_list);
 	}
 
 restart:
@@ -471,6 +470,7 @@ restart:
 		sb->s_count++;
 		spin_unlock(&sb_lock);
 		down_read(&sb->s_umount);
+		async_synchronize_full_special(&sb->s_async_list);
 		if (sb->s_root && (wait || sb->s_dirt))
 			sb->s_op->sync_fs(sb, wait);
 		up_read(&sb->s_umount);