[4/4] pNFS: Don't forget the layout stateid if there are outstanding LAYOUTGETs
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Message ID 1473083162-4697-5-git-send-email-trond.myklebust@primarydata.com
State New
Headers show

Commit Message

Trond Myklebust Sept. 5, 2016, 1:46 p.m. UTC
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

Patch
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======				======
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 | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index cd8b5fca33f6..2c93a85eda51 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -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);