NFSv4.x: fix lock recovery during delegation recall

Running "./nfstest_delegation --runtest recall26" uncovers that
client doesn't recover the lock when we have an appending open,
where the initial open got a write delegation.

Instead of checking for the passed in open context against
the file lock's open context. Check that the state is the same.
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/delegation.c

@@ -93,7 +93,7 @@ int nfs4_check_delegation(struct inode *inode, fmode_t flags)
 	return nfs4_do_check_delegation(inode, flags, false);
 }
 
-static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_state *state, const nfs4_stateid *stateid)
+static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid)
 {
 	struct inode *inode = state->inode;
 	struct file_lock *fl;
@@ -108,7 +108,7 @@ static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_
 	spin_lock(&flctx->flc_lock);
 restart:
 	list_for_each_entry(fl, list, fl_list) {
-		if (nfs_file_open_context(fl->fl_file) != ctx)
+		if (nfs_file_open_context(fl->fl_file)->state != state)
 			continue;
 		spin_unlock(&flctx->flc_lock);
 		status = nfs4_lock_delegation_recall(fl, state, stateid);
@@ -156,7 +156,7 @@ static int nfs_delegation_claim_opens(struct inode *inode,
 		seq = raw_seqcount_begin(&sp->so_reclaim_seqcount);
 		err = nfs4_open_delegation_recall(ctx, state, stateid, type);
 		if (!err)
-			err = nfs_delegation_claim_locks(ctx, state, stateid);
+			err = nfs_delegation_claim_locks(state, stateid);
 		if (!err && read_seqcount_retry(&sp->so_reclaim_seqcount, seq))
 			err = -EAGAIN;
 		mutex_unlock(&sp->so_delegreturn_mutex);