pNFS: Force a retry of LAYOUTGET if the stateid doesn't match our cache

If the server sends us a completely new stateid, and the client thinks
it already holds a layout, then force a retry of the LAYOUTGET after
invalidating the existing layout in order to avoid corruption due to
races.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index d4e06b7459f4..9b7e88b7edfc 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1844,7 +1844,10 @@ pnfs_layout_process(struct nfs4_layoutget *lgp)
                 goto out_forget;
         }
 
-        if (nfs4_stateid_match_other(&lo->plh_stateid, &res->stateid)) {
+        if (!pnfs_layout_is_valid(lo)) {
+                /* We have a completely new layout */
+                pnfs_set_layout_stateid(lo, &res->stateid, true);
+        } else if (nfs4_stateid_match_other(&lo->plh_stateid, &res->stateid)) {
                 /* existing state ID, make sure the sequence number matches. */
                 if (pnfs_layout_stateid_blocked(lo, &res->stateid)) {
                         dprintk("%s forget reply due to sequence\n", __func__);
@@ -1854,12 +1857,10 @@ pnfs_layout_process(struct nfs4_layoutget *lgp)
         } else {
                 /*
                  * We got an entirely new state ID.  Mark all segments for the
-                 * inode invalid, and don't bother validating the stateid
-                 * sequence number.
+                 * inode invalid, and retry the layoutget
                  */
                 pnfs_mark_layout_stateid_invalid(lo, &free_me);
-
-                pnfs_set_layout_stateid(lo, &res->stateid, true);
+                goto out_forget;
         }
 
         pnfs_get_lseg(lseg);