NFSv4.1/pnfs: Handle LAYOUTGET return values correctly

According to RFC5661 section 18.43.3, if the server cannot satisfy
the loga_minlength argument to LAYOUTGET, there are 2 cases:
1) If loga_minlength == 0, it returns NFS4ERR_LAYOUTTRYLATER
2) If loga_minlength != 0, it returns NFS4ERR_BADLAYOUT

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

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 366b81c..51c7164 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -7780,11 +7780,20 @@ static void nfs4_layoutget_done(struct rpc_task *task, void *calldata)
        switch (task->tk_status) {
        case 0:
                goto out;
+       /*
+        * NFS4ERR_BADLAYOUT means the MDS cannot return a layout of
+        * length lgp->args.minlength != 0 (see RFC5661 section 18.43.3).
+        */
+       case -NFS4ERR_BADLAYOUT:
+               goto out_overflow;
        /*
         * NFS4ERR_LAYOUTTRYLATER is a conflict with another client
-        * (or clients) writing to the same RAID stripe
+        * (or clients) writing to the same RAID stripe except when
+        * the minlength argument is 0 (see RFC5661 section 18.43.3).
         */
        case -NFS4ERR_LAYOUTTRYLATER:
+               if (lgp->args.minlength == 0)
+                       goto out_overflow;
        /*
         * NFS4ERR_RECALLCONFLICT is when conflict with self (must recall
         * existing layout before getting a new one).
@@ -7840,6 +7849,10 @@ static void nfs4_layoutget_done(struct rpc_task *task, void *calldata)
                rpc_restart_call_prepare(task);
 out:
        dprintk("<-- %s\n", __func__);
+       return;
+out_overflow:
+       task->tk_status = -EOVERFLOW;
+       goto out;
 }
 
 static size_t max_response_pages(struct nfs_server *server)