[patch 16/21] mutex subsystem, semaphore to mutex: VFS, sb->s_lock

[Ingo Molnar <mingo@elte.hu>]

This patch converts the superblock-lock semaphore to a mutex, affecting
lock_super()/unlock_super(). Tested on ext3 and XFS.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

----

 fs/ext3/super.c    |    2 +-
 fs/super.c         |    2 +-
 include/linux/fs.h |    6 +++---
 3 files changed, 5 insertions(+), 5 deletions(-)

Index: linux/fs/ext3/super.c
===================================================================
--- linux.orig/fs/ext3/super.c
+++ linux/fs/ext3/super.c
@@ -2116,7 +2116,7 @@ int ext3_force_commit(struct super_block
 
 static void ext3_write_super (struct super_block * sb)
 {
-	if (down_trylock(&sb->s_lock) == 0)
+	if (mutex_trylock(&sb->s_lock) != 0)
 		BUG();
 	sb->s_dirt = 0;
 }
Index: linux/fs/super.c
===================================================================
--- linux.orig/fs/super.c
+++ linux/fs/super.c
@@ -72,7 +72,7 @@ static struct super_block *alloc_super(v
 		INIT_HLIST_HEAD(&s->s_anon);
 		INIT_LIST_HEAD(&s->s_inodes);
 		init_rwsem(&s->s_umount);
-		sema_init(&s->s_lock, 1);
+		mutex_init(&s->s_lock);
 		down_write(&s->s_umount);
 		s->s_count = S_BIAS;
 		atomic_set(&s->s_active, 1);
Index: linux/include/linux/fs.h
===================================================================
--- linux.orig/include/linux/fs.h
+++ linux/include/linux/fs.h
@@ -791,7 +791,7 @@ struct super_block {
 	unsigned long		s_magic;
 	struct dentry		*s_root;
 	struct rw_semaphore	s_umount;
-	struct semaphore	s_lock;
+	struct mutex		s_lock;
 	int			s_count;
 	int			s_syncing;
 	int			s_need_sync_fs;
@@ -863,13 +863,13 @@ static inline int has_fs_excl(void)
 static inline void lock_super(struct super_block * sb)
 {
 	get_fs_excl();
-	down(&sb->s_lock);
+	mutex_lock(&sb->s_lock);
 }
 
 static inline void unlock_super(struct super_block * sb)
 {
 	put_fs_excl();
-	up(&sb->s_lock);
+	mutex_unlock(&sb->s_lock);
 }
 
 /*