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>

1 files changed, 4 insertions, 15 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 1c71fc213716..ee9a179ebdf3 100644
--- 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);