nfs41: close a small race window when adding new layout to global list

Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Tom Haynes <Thomas.Haynes@primarydata.com>

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 2d25670..fa00b56 100644 (file)
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1288,7 +1288,6 @@ pnfs_update_layout(struct inode *ino,
        struct nfs_client *clp = server->nfs_client;
        struct pnfs_layout_hdr *lo;
        struct pnfs_layout_segment *lseg = NULL;
-       bool first;
 
        if (!pnfs_enabled_sb(NFS_SERVER(ino)))
                goto out;
@@ -1321,16 +1320,15 @@ pnfs_update_layout(struct inode *ino,
        if (pnfs_layoutgets_blocked(lo, 0))
                goto out_unlock;
        atomic_inc(&lo->plh_outstanding);
-
-       first = list_empty(&lo->plh_layouts) ? true : false;
        spin_unlock(&ino->i_lock);
 
-       if (first) {
+       if (list_empty(&lo->plh_layouts)) {
                /* The lo must be on the clp list if there is any
                 * chance of a CB_LAYOUTRECALL(FILE) coming in.
                 */
                spin_lock(&clp->cl_lock);
-               list_add_tail(&lo->plh_layouts, &server->layouts);
+               if (list_empty(&lo->plh_layouts))
+                       list_add_tail(&lo->plh_layouts, &server->layouts);
                spin_unlock(&clp->cl_lock);
        }