NFS: Don't call iput() in nfs_access_cache_shrinker

iput() can potentially attempt to allocate memory, so we should avoid
calling it in a memory shrinker. Instead, rely on the fact that iput() will
call nfs_access_zap_cache().

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 1c71fc2..ee9a179 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1716,22 +1716,14 @@ int nfs_access_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)
 
        if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
                return (nr_to_scan == 0) ? 0 : -1;
-restart:
+
        spin_lock(&nfs_access_lru_lock);
        list_for_each_entry(nfsi, &nfs_access_lru_list, access_cache_inode_lru) {
-               struct rw_semaphore *s_umount;
                struct inode *inode;
 
                if (nr_to_scan-- == 0)
                        break;
-               s_umount = &nfsi->vfs_inode.i_sb->s_umount;
-               if (!down_read_trylock(s_umount))
-                       continue;
-               inode = igrab(&nfsi->vfs_inode);
-               if (inode == NULL) {
-                       up_read(s_umount);
-                       continue;
-               }
+               inode = &nfsi->vfs_inode;
                spin_lock(&inode->i_lock);
                if (list_empty(&nfsi->access_cache_entry_lru))
                        goto remove_lru_entry;
@@ -1745,13 +1737,10 @@ restart:
                else {
 remove_lru_entry:
                        list_del_init(&nfsi->access_cache_inode_lru);
+                       smp_mb__before_clear_bit();
                        clear_bit(NFS_INO_ACL_LRU_SET, &nfsi->flags);
+                       smp_mb__after_clear_bit();
                }
-               spin_unlock(&inode->i_lock);
-               spin_unlock(&nfs_access_lru_lock);
-               iput(inode);
-               up_read(s_umount);
-               goto restart;
        }
        spin_unlock(&nfs_access_lru_lock);
        nfs_access_free_list(&head);