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>

1 files changed, 3 insertions, 5 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 2d25670bbe44..fa00b56f176a 100644
--- 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);
         }