NFS: Fix nfs_post_op_update_inode_force_wcc()

If we believe that the attributes are old (see nfs_refresh_inode()), then
we shouldn't force an update.
Also ensure that we hold the inode->i_lock across attribute checks and the
call to nfs_refresh_inode_locked() to ensure that we don't race with other
attribute updates.

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

1 files changed, 27 insertions, 8 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 8c514a1353c0..610d022fc7a5 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1017,6 +1017,18 @@ int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
         return status;
 }
 
+static int nfs_post_op_update_inode_locked(struct inode *inode, struct nfs_fattr *fattr)
+{
+        struct nfs_inode *nfsi = NFS_I(inode);
+
+        nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
+        if (S_ISDIR(inode->i_mode))
+                nfsi->cache_validity |= NFS_INO_INVALID_DATA;
+        if ((fattr->valid & NFS_ATTR_FATTR) == 0)
+                return 0;
+        return nfs_refresh_inode_locked(inode, fattr);
+}
+
 /**
  * nfs_post_op_update_inode - try to update the inode attribute cache
  * @inode - pointer to inode
@@ -1033,15 +1045,10 @@ int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr)
  */
 int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 {
-        struct nfs_inode *nfsi = NFS_I(inode);
-        int status = 0;
+        int status;
 
         spin_lock(&inode->i_lock);
-        nfsi->cache_validity |= NFS_INO_INVALID_ATTR|NFS_INO_REVAL_PAGECACHE;
-        if (S_ISDIR(inode->i_mode))
-                nfsi->cache_validity |= NFS_INO_INVALID_DATA;
-        if ((fattr->valid & NFS_ATTR_FATTR) != 0)
-                status = nfs_refresh_inode_locked(inode, fattr);
+        status = nfs_post_op_update_inode_locked(inode, fattr);
         spin_unlock(&inode->i_lock);
         return status;
 }
@@ -1059,6 +1066,15 @@ int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr)
  */
 int nfs_post_op_update_inode_force_wcc(struct inode *inode, struct nfs_fattr *fattr)
 {
+        int status;
+
+        spin_lock(&inode->i_lock);
+        /* Don't do a WCC update if these attributes are already stale */
+        if ((fattr->valid & NFS_ATTR_FATTR) == 0 ||
+                        !nfs_inode_attrs_need_update(inode, fattr)) {
+                fattr->valid &= ~(NFS_ATTR_WCC_V4|NFS_ATTR_WCC);
+                goto out_noforce;
+        }
         if ((fattr->valid & NFS_ATTR_FATTR_V4) != 0 &&
                         (fattr->valid & NFS_ATTR_WCC_V4) == 0) {
                 fattr->pre_change_attr = NFS_I(inode)->change_attr;
@@ -1071,7 +1087,10 @@ int nfs_post_op_update_inode_force_wcc(struct inode *inode, struct nfs_fattr *fa
                 fattr->pre_size = i_size_read(inode);
                 fattr->valid |= NFS_ATTR_WCC;
         }
-        return nfs_post_op_update_inode(inode, fattr);
+out_noforce:
+        status = nfs_post_op_update_inode_locked(inode, fattr);
+        spin_unlock(&inode->i_lock);
+        return status;
 }
 
 /*