reiserfs: locking, handle nested locks properly
The reiserfs write lock replaced the BKL and uses similar semantics.
Frederic's locking code makes a distinction between when the lock is nested
and when it's being acquired/released, but I don't think that's the right
distinction to make.
The right distinction is between the lock being released at end-of-use and
the lock being released for a schedule. The unlock should return the depth
and the lock should restore it, rather than the other way around as it is now.
This patch implements that and adds a number of places where the lock
should be dropped.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
diff --git a/fs/reiserfs/reiserfs.h b/fs/reiserfs/reiserfs.h
index 3df5ce6..f8adaee 100644
--- a/fs/reiserfs/reiserfs.h
+++ b/fs/reiserfs/reiserfs.h
@@ -630,8 +630,8 @@
*/
void reiserfs_write_lock(struct super_block *s);
void reiserfs_write_unlock(struct super_block *s);
-int reiserfs_write_lock_once(struct super_block *s);
-void reiserfs_write_unlock_once(struct super_block *s, int lock_depth);
+int __must_check reiserfs_write_unlock_nested(struct super_block *s);
+void reiserfs_write_lock_nested(struct super_block *s, int depth);
#ifdef CONFIG_REISERFS_CHECK
void reiserfs_lock_check_recursive(struct super_block *s);
@@ -667,31 +667,33 @@
* - The inode mutex
*/
static inline void reiserfs_mutex_lock_safe(struct mutex *m,
- struct super_block *s)
+ struct super_block *s)
{
- reiserfs_lock_check_recursive(s);
- reiserfs_write_unlock(s);
+ int depth;
+
+ depth = reiserfs_write_unlock_nested(s);
mutex_lock(m);
- reiserfs_write_lock(s);
+ reiserfs_write_lock_nested(s, depth);
}
static inline void
reiserfs_mutex_lock_nested_safe(struct mutex *m, unsigned int subclass,
- struct super_block *s)
+ struct super_block *s)
{
- reiserfs_lock_check_recursive(s);
- reiserfs_write_unlock(s);
+ int depth;
+
+ depth = reiserfs_write_unlock_nested(s);
mutex_lock_nested(m, subclass);
- reiserfs_write_lock(s);
+ reiserfs_write_lock_nested(s, depth);
}
static inline void
reiserfs_down_read_safe(struct rw_semaphore *sem, struct super_block *s)
{
- reiserfs_lock_check_recursive(s);
- reiserfs_write_unlock(s);
- down_read(sem);
- reiserfs_write_lock(s);
+ int depth;
+ depth = reiserfs_write_unlock_nested(s);
+ down_read(sem);
+ reiserfs_write_lock_nested(s, depth);
}
/*
@@ -701,9 +703,11 @@
static inline void reiserfs_cond_resched(struct super_block *s)
{
if (need_resched()) {
- reiserfs_write_unlock(s);
+ int depth;
+
+ depth = reiserfs_write_unlock_nested(s);
schedule();
- reiserfs_write_lock(s);
+ reiserfs_write_lock_nested(s, depth);
}
}