pNFS: Don't forget the layout stateid if there are outstanding LAYOUTGETs
authorTrond Myklebust <trond.myklebust@primarydata.com>
Sun, 4 Sep 2016 16:46:35 +0000 (12:46 -0400)
committerTrond Myklebust <trond.myklebust@primarydata.com>
Sun, 4 Sep 2016 16:59:00 +0000 (12:59 -0400)
If there are outstanding LAYOUTGET rpc calls, then we want to ensure that
we keep the layout stateid around so we that don't inadvertently pick up
an old/misordered sequence id.
The race is as follows:

Client Server
====== ======
LAYOUTGET(seqid)
LAYOUTGET(seqid)
return LAYOUTGET(seqid+1)
return LAYOUTGET(seqid+2)
process LAYOUTGET(seqid+2)
forget layout
process LAYOUTGET(seqid+1)

If it forgets the layout stateid before processing seqid+1, then
the client will not check the layout->plh_barrier, and so will set
the stateid with seqid+1.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
fs/nfs/pnfs.c

index cd8b5fca33f6e2740d048fcaf055dde0cd3146ee..2c93a85eda51c9d6ebcde892d1e7ca60a1f159b3 100644 (file)
@@ -365,7 +365,8 @@ pnfs_layout_remove_lseg(struct pnfs_layout_hdr *lo,
        /* Matched by pnfs_get_layout_hdr in pnfs_layout_insert_lseg */
        atomic_dec(&lo->plh_refcount);
        if (list_empty(&lo->plh_segs)) {
-               set_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
+               if (atomic_read(&lo->plh_outstanding) == 0)
+                       set_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
                clear_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags);
        }
        rpc_wake_up(&NFS_SERVER(inode)->roc_rpcwaitq);