pNFS: Don't forget the layout stateid if there are outstanding LAYOUTGETs
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>
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index cd8b5fc..2c93a85 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -365,7 +365,8 @@
/* 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);