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>

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 8c514a1..610d022 100644 (file)
--- 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;
 }
 
 /*