No need to do lock_super() for exclusion in generic_shutdown_super()

We can't run into contention on it.  All other callers of lock_super()
either hold s_umount (and we have it exclusive) or hold an active
reference to superblock in question, which prevents the call of
generic_shutdown_super() while the reference is held.  So we can
replace lock_super(s) with get_fs_excl() in generic_shutdown_super()
(and corresponding change for unlock_super(), of course).

Since ext4 expects s_lock held for its put_super, take lock_super()
into it.  The rest of filesystems do not care at all.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/super.c b/fs/super.c
index 49f670c..54fd331 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -304,7 +304,7 @@ void generic_shutdown_super(struct super_block *sb)
 	if (sb->s_root) {
 		shrink_dcache_for_umount(sb);
 		sync_filesystem(sb);
-		lock_super(sb);
+		get_fs_excl();
 		sb->s_flags &= ~MS_ACTIVE;
 
 		/* bad name - it should be evict_inodes() */
@@ -322,7 +322,7 @@ void generic_shutdown_super(struct super_block *sb)
 		}
 
 		unlock_kernel();
-		unlock_super(sb);
+		put_fs_excl();
 	}
 	spin_lock(&sb_lock);
 	/* should be initialized for __put_super_and_need_restart() */