[PATCH 4.14 096/105] NFSv4: Dont allow a cached open with a revoked delegation

[Greg Kroah-Hartman]

From: Trond Myklebust <trondmy@xxxxxxxxx>

[ Upstream commit be3df3dd4c70ee020587a943a31b98a0fb4b6424 ]

If the delegation is marked as being revoked, we must not use it
for cached opens.

Fixes: 869f9dfa4d6d ("NFSv4: Fix races between nfs_remove_bad_delegation() and delegation return")
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/nfs/delegation.c | 10 ++++++++++
 fs/nfs/delegation.h |  1 +
 fs/nfs/nfs4proc.c   |  7 ++-----
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 606dd3871f66b..61bc0a6ba08b1 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -52,6 +52,16 @@ nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
 	return false;
 }
 
+struct nfs_delegation *nfs4_get_valid_delegation(const struct inode *inode)
+{
+	struct nfs_delegation *delegation;
+
+	delegation = rcu_dereference(NFS_I(inode)->delegation);
+	if (nfs4_is_valid_delegation(delegation, 0))
+		return delegation;
+	return NULL;
+}
+
 static int
 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
 {
diff --git a/fs/nfs/delegation.h b/fs/nfs/delegation.h
index ddaf2644cf13a..df41d16dc6ab4 100644
--- a/fs/nfs/delegation.h
+++ b/fs/nfs/delegation.h
@@ -63,6 +63,7 @@ int nfs4_open_delegation_recall(struct nfs_open_context *ctx, struct nfs4_state
 int nfs4_lock_delegation_recall(struct file_lock *fl, struct nfs4_state *state, const nfs4_stateid *stateid);
 bool nfs4_copy_delegation_stateid(struct inode *inode, fmode_t flags, nfs4_stateid *dst, struct rpc_cred **cred);
 
+struct nfs_delegation *nfs4_get_valid_delegation(const struct inode *inode);
 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation);
 int nfs4_have_delegation(struct inode *inode, fmode_t flags);
 int nfs4_check_delegation(struct inode *inode, fmode_t flags);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index af062e9f45803..f1526f65cc580 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1355,8 +1355,6 @@ static int can_open_delegated(struct nfs_delegation *delegation, fmode_t fmode,
 		return 0;
 	if ((delegation->type & fmode) != fmode)
 		return 0;
-	if (test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
-		return 0;
 	switch (claim) {
 	case NFS4_OPEN_CLAIM_NULL:
 	case NFS4_OPEN_CLAIM_FH:
@@ -1615,7 +1613,6 @@ static void nfs4_return_incompatible_delegation(struct inode *inode, fmode_t fmo
 static struct nfs4_state *nfs4_try_open_cached(struct nfs4_opendata *opendata)
 {
 	struct nfs4_state *state = opendata->state;
-	struct nfs_inode *nfsi = NFS_I(state->inode);
 	struct nfs_delegation *delegation;
 	int open_mode = opendata->o_arg.open_flags;
 	fmode_t fmode = opendata->o_arg.fmode;
@@ -1632,7 +1629,7 @@ static struct nfs4_state *nfs4_try_open_cached(struct nfs4_opendata *opendata)
 		}
 		spin_unlock(&state->owner->so_lock);
 		rcu_read_lock();
-		delegation = rcu_dereference(nfsi->delegation);
+		delegation = nfs4_get_valid_delegation(state->inode);
 		if (!can_open_delegated(delegation, fmode, claim)) {
 			rcu_read_unlock();
 			break;
@@ -2153,7 +2150,7 @@ static void nfs4_open_prepare(struct rpc_task *task, void *calldata)
 					data->o_arg.open_flags, claim))
 			goto out_no_action;
 		rcu_read_lock();
-		delegation = rcu_dereference(NFS_I(data->state->inode)->delegation);
+		delegation = nfs4_get_valid_delegation(data->state->inode);
 		if (can_open_delegated(delegation, data->o_arg.fmode, claim))
 			goto unlock_no_action;
 		rcu_read_unlock();
-- 
2.20.1