MIPS: SEAD3: Use symbolic addresses from sead-addr.h in LED driver.

[linux-drm-fsl-dcu.git] / fs / super.c

diff --git a/fs/super.c b/fs/super.c
index 65a53efc1cf4a5d5ce5cb7c6eca39fa28b0d2f7f..2b7dc90ccdbb4ae1ceac7725967cec2a643e21c7 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -71,7 +71,7 @@ static unsigned long super_cache_scan(struct shrinker *shrink,
        if (!(sc->gfp_mask & __GFP_FS))
                return SHRINK_STOP;
 
-       if (!grab_super_passive(sb))
+       if (!trylock_super(sb))
                return SHRINK_STOP;
 
        if (sb->s_op->nr_cached_objects)
@@ -105,7 +105,7 @@ static unsigned long super_cache_scan(struct shrinker *shrink,
                freed += sb->s_op->free_cached_objects(sb, sc);
        }
 
-       drop_super(sb);
+       up_read(&sb->s_umount);
        return freed;
 }
 
@@ -118,7 +118,7 @@ static unsigned long super_cache_count(struct shrinker *shrink,
        sb = container_of(shrink, struct super_block, s_shrink);
 
        /*
-        * Don't call grab_super_passive as it is a potential
+        * Don't call trylock_super as it is a potential
         * scalability bottleneck. The counts could get updated
         * between super_cache_count and super_cache_scan anyway.
         * Call to super_cache_count with shrinker_rwsem held
@@ -348,35 +348,31 @@ static int grab_super(struct super_block *s) __releases(sb_lock)
 }
 
 /*
- *     grab_super_passive - acquire a passive reference
+ *     trylock_super - try to grab ->s_umount shared
  *     @sb: reference we are trying to grab
  *
- *     Tries to acquire a passive reference. This is used in places where we
+ *     Try to prevent fs shutdown.  This is used in places where we
  *     cannot take an active reference but we need to ensure that the
- *     superblock does not go away while we are working on it. It returns
- *     false if a reference was not gained, and returns true with the s_umount
- *     lock held in read mode if a reference is gained. On successful return,
- *     the caller must drop the s_umount lock and the passive reference when
- *     done.
+ *     filesystem is not shut down while we are working on it. It returns
+ *     false if we cannot acquire s_umount or if we lose the race and
+ *     filesystem already got into shutdown, and returns true with the s_umount
+ *     lock held in read mode in case of success. On successful return,
+ *     the caller must drop the s_umount lock when done.
+ *
+ *     Note that unlike get_super() et.al. this one does *not* bump ->s_count.
+ *     The reason why it's safe is that we are OK with doing trylock instead
+ *     of down_read().  There's a couple of places that are OK with that, but
+ *     it's very much not a general-purpose interface.
  */
-bool grab_super_passive(struct super_block *sb)
+bool trylock_super(struct super_block *sb)
 {
-       spin_lock(&sb_lock);
-       if (hlist_unhashed(&sb->s_instances)) {
-               spin_unlock(&sb_lock);
-               return false;
-       }
-
-       sb->s_count++;
-       spin_unlock(&sb_lock);
-
        if (down_read_trylock(&sb->s_umount)) {
-               if (sb->s_root && (sb->s_flags & MS_BORN))
+               if (!hlist_unhashed(&sb->s_instances) &&
+                   sb->s_root && (sb->s_flags & MS_BORN))
                        return true;
                up_read(&sb->s_umount);
        }
 
-       put_super(sb);
        return false;
 }