Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso...

[cascardo/linux.git] / fs / super.c

diff --git a/fs/super.c b/fs/super.c
index e9dc3c3..d20d5b1 100644 (file)
--- a/fs/super.c
+++ b/fs/super.c
@@ -112,9 +112,14 @@ static unsigned long super_cache_count(struct shrinker *shrink,
 
        sb = container_of(shrink, struct super_block, s_shrink);
 
-       if (!grab_super_passive(sb))
-               return 0;
-
+       /*
+        * Don't call grab_super_passive 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
+        * ensures the safety of call to list_lru_count_node() and
+        * s_op->nr_cached_objects().
+        */
        if (sb->s_op && sb->s_op->nr_cached_objects)
                total_objects = sb->s_op->nr_cached_objects(sb,
                                                 sc->nid);
@@ -125,7 +130,6 @@ static unsigned long super_cache_count(struct shrinker *shrink,
                                                 sc->nid);
 
        total_objects = vfs_pressure_ratio(total_objects);
-       drop_super(sb);
        return total_objects;
 }
 
@@ -276,10 +280,8 @@ void deactivate_locked_super(struct super_block *s)
        struct file_system_type *fs = s->s_type;
        if (atomic_dec_and_test(&s->s_active)) {
                cleancache_invalidate_fs(s);
-               fs->kill_sb(s);
-
-               /* caches are now gone, we can safely kill the shrinker now */
                unregister_shrinker(&s->s_shrink);
+               fs->kill_sb(s);
 
                put_filesystem(fs);
                put_super(s);
@@ -800,7 +802,10 @@ void emergency_remount(void)
 
 static DEFINE_IDA(unnamed_dev_ida);
 static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
-static int unnamed_dev_start = 0; /* don't bother trying below it */
+/* Many userspace utilities consider an FSID of 0 invalid.
+ * Always return at least 1 from get_anon_bdev.
+ */
+static int unnamed_dev_start = 1;
 
 int get_anon_bdev(dev_t *p)
 {