1 files changed, 40 insertions, 13 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 8220a168282e..db84b4adbc49 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1349,12 +1349,20 @@ static bool nfs4_mode_match_open_stateid(struct nfs4_state *state,
 	return false;
 }
 
-static int can_open_cached(struct nfs4_state *state, fmode_t mode, int open_mode)
+static int can_open_cached(struct nfs4_state *state, fmode_t mode,
+		int open_mode, enum open_claim_type4 claim)
 {
 	int ret = 0;
 
 	if (open_mode & (O_EXCL|O_TRUNC))
 		goto out;
+	switch (claim) {
+	case NFS4_OPEN_CLAIM_NULL:
+	case NFS4_OPEN_CLAIM_FH:
+		goto out;
+	default:
+		break;
+	}
 	switch (mode & (FMODE_READ|FMODE_WRITE)) {
 		case FMODE_READ:
 			ret |= test_bit(NFS_O_RDONLY_STATE, &state->flags) != 0
@@ -1747,7 +1755,7 @@ static struct nfs4_state *nfs4_try_open_cached(struct nfs4_opendata *opendata)
 
 	for (;;) {
 		spin_lock(&state->owner->so_lock);
-		if (can_open_cached(state, fmode, open_mode)) {
+		if (can_open_cached(state, fmode, open_mode, claim)) {
 			update_open_stateflags(state, fmode);
 			spin_unlock(&state->owner->so_lock);
 			goto out_return_state;
@@ -1777,7 +1785,7 @@ static struct nfs4_state *nfs4_try_open_cached(struct nfs4_opendata *opendata)
 out:
 	return ERR_PTR(ret);
 out_return_state:
-	atomic_inc(&state->count);
+	refcount_inc(&state->count);
 	return state;
 }
 
@@ -1849,7 +1857,7 @@ _nfs4_opendata_reclaim_to_nfs4_state(struct nfs4_opendata *data)
 update:
 	update_open_stateid(state, &data->o_res.stateid, NULL,
 			    data->o_arg.fmode);
-	atomic_inc(&state->count);
+	refcount_inc(&state->count);
 
 	return state;
 }
@@ -1887,7 +1895,7 @@ nfs4_opendata_find_nfs4_state(struct nfs4_opendata *data)
 		return ERR_CAST(inode);
 	if (data->state != NULL && data->state->inode == inode) {
 		state = data->state;
-		atomic_inc(&state->count);
+		refcount_inc(&state->count);
 	} else
 		state = nfs4_get_open_state(inode, data->owner);
 	iput(inode);
@@ -1933,23 +1941,41 @@ nfs4_opendata_to_nfs4_state(struct nfs4_opendata *data)
 	return ret;
 }
 
-static struct nfs_open_context *nfs4_state_find_open_context(struct nfs4_state *state)
+static struct nfs_open_context *
+nfs4_state_find_open_context_mode(struct nfs4_state *state, fmode_t mode)
 {
 	struct nfs_inode *nfsi = NFS_I(state->inode);
 	struct nfs_open_context *ctx;
 
-	spin_lock(&state->inode->i_lock);
-	list_for_each_entry(ctx, &nfsi->open_files, list) {
+	rcu_read_lock();
+	list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {
 		if (ctx->state != state)
 			continue;
-		get_nfs_open_context(ctx);
-		spin_unlock(&state->inode->i_lock);
+		if ((ctx->mode & mode) != mode)
+			continue;
+		if (!get_nfs_open_context(ctx))
+			continue;
+		rcu_read_unlock();
 		return ctx;
 	}
-	spin_unlock(&state->inode->i_lock);
+	rcu_read_unlock();
 	return ERR_PTR(-ENOENT);
 }
 
+static struct nfs_open_context *
+nfs4_state_find_open_context(struct nfs4_state *state)
+{
+	struct nfs_open_context *ctx;
+
+	ctx = nfs4_state_find_open_context_mode(state, FMODE_READ|FMODE_WRITE);
+	if (!IS_ERR(ctx))
+		return ctx;
+	ctx = nfs4_state_find_open_context_mode(state, FMODE_WRITE);
+	if (!IS_ERR(ctx))
+		return ctx;
+	return nfs4_state_find_open_context_mode(state, FMODE_READ);
+}
+
 static struct nfs4_opendata *nfs4_open_recoverdata_alloc(struct nfs_open_context *ctx,
 		struct nfs4_state *state, enum open_claim_type4 claim)
 {
@@ -1960,7 +1986,7 @@ static struct nfs4_opendata *nfs4_open_recoverdata_alloc(struct nfs_open_context
 	if (opendata == NULL)
 		return ERR_PTR(-ENOMEM);
 	opendata->state = state;
-	atomic_inc(&state->count);
+	refcount_inc(&state->count);
 	return opendata;
 }
 
@@ -2276,7 +2302,8 @@ static void nfs4_open_prepare(struct rpc_task *task, void *calldata)
 	if (data->state != NULL) {
 		struct nfs_delegation *delegation;
 
-		if (can_open_cached(data->state, data->o_arg.fmode, data->o_arg.open_flags))
+		if (can_open_cached(data->state, data->o_arg.fmode,
+					data->o_arg.open_flags, claim))
 			goto out_no_action;
 		rcu_read_lock();
 		delegation = rcu_dereference(NFS_I(data->state->inode)->delegation);