Disable zpl_nr_cached_objects() callback

The zpl_nr_cached_objects() function has been disabled because in the
current code it doesn't provide any critical functionality and it may
result in a deadlock under certain circumstances.  However, because
we expect to need these hooks in the future this code has not been
entirely removed.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #3719

diff --git a/module/zfs/zpl_super.c b/module/zfs/zpl_super.c
index 87895d6ba2b2414d95458fea54382497a4ddc52c..bcdbbd69e2808e56d8b6588f9ed77aab19b5b745 100644 (file)
--- a/module/zfs/zpl_super.c
+++ b/module/zfs/zpl_super.c
@@ -501,24 +501,11 @@ zpl_prune_sb(int64_t nr_to_scan, void *arg)
 static int
 zpl_nr_cached_objects(struct super_block *sb)
 {
-       zfs_sb_t *zsb = sb->s_fs_info;
-       int nr;
-
-       mutex_enter(&zsb->z_znodes_lock);
-       nr = zsb->z_nr_znodes;
-       mutex_exit(&zsb->z_znodes_lock);
-
-       return (nr);
+       return (0);
 }
 #endif /* HAVE_NR_CACHED_OBJECTS */
 
 #ifdef HAVE_FREE_CACHED_OBJECTS
-/*
- * Attempt to evict some meta data from the cache.  The ARC operates in
- * terms of bytes while the Linux VFS uses objects.  Now because this is
- * just a best effort eviction and the exact values aren't critical so we
- * extrapolate from an object count to a byte size using the znode_t size.
- */
 static void
 zpl_free_cached_objects(struct super_block *sb, int nr_to_scan)
 {