[PATCH v2 1/1] NFSv4.1: Apply session size limits on clone path

Tushar Sariya
2026-04-04T14:28:45Z

From: Tushar Sariya <tushar.97@hotmail.com>

nfs4_clone_server() builds a child nfs_server for same-server
automounted submounts but never calls nfs4_session_limit_rwsize()
or nfs4_session_limit_xasize() after nfs_clone_server(). This means
the child mount can end up with rsize/wsize values that exceed the
negotiated session channel limits, causing NFS4ERR_REQ_TOO_BIG and
EIO on servers that enforce tight max_request_size budgets.

Top-level mounts go through nfs4_server_common_setup() which calls
these limiters after nfs_probe_server(). Apply the same clamping on
the clone path for consistency.

Fixes: 2b092175f5e3 ("NFS: Fix inheritance of the block sizes when automounting")
Cc: stable@vger.kernel.org
Signed-off-by: Tushar Sariya <tushar.97@hotmail.com>
---
fs/nfs/internal.h | 2 ++
fs/nfs/nfs4client.c | 4 ++--
fs/nfs/nfs4proc.c | 3 +++
3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 63e09dfc27a8..0338603e9674 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -253,6 +253,8 @@ extern struct nfs_client *nfs4_set_ds_client(struct nfs_server *mds_srv,
u32 minor_version);
extern struct rpc_clnt *nfs4_find_or_create_ds_client(struct nfs_client *,
struct inode *);
+extern void nfs4_session_limit_rwsize(struct nfs_server *server);
+extern void nfs4_session_limit_xasize(struct nfs_server *server);
extern struct nfs_client *nfs3_set_ds_client(struct nfs_server *mds_srv,
const struct sockaddr_storage *ds_addr, int ds_addrlen,
int ds_proto, unsigned int ds_timeo,
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index c211639949c2..71c271a1700a 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -855,7 +855,7 @@ EXPORT_SYMBOL_GPL(nfs4_set_ds_client);
* Limit the mount rsize, wsize and dtsize using negotiated fore
* channel attributes.
*/
-static void nfs4_session_limit_rwsize(struct nfs_server *server)
+void nfs4_session_limit_rwsize(struct nfs_server *server)
{
struct nfs4_session *sess;
u32 server_resp_sz;
@@ -878,7 +878,7 @@ static void nfs4_session_limit_rwsize(struct nfs_server *server)
/*
* Limit xattr sizes using the channel attributes.
*/
-static void nfs4_session_limit_xasize(struct nfs_server *server)
+void nfs4_session_limit_xasize(struct nfs_server *server)
{
#ifdef CONFIG_NFS_V4_2
struct nfs4_session *sess;
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 91bcf67bd743..655617ffca8d 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -10618,6 +10618,9 @@ static struct nfs_server *nfs4_clone_server(struct nfs_server *source,
if (IS_ERR(server))
return server;

+ nfs4_session_limit_rwsize(server);
+ nfs4_session_limit_xasize(server);
+
error = nfs4_delegation_hash_alloc(server);
if (error) {
nfs_free_server(server);
--
2.43.0