[PATCH 6.1 408/473] nfs: keep server info for remounts

Greg Kroah-Hartman
2024-06-06T14:19:00Z

From: Martin Kaiser <martin@kaiser.cx>

[ Upstream commit b322bf9e983addedff0894c55e92d58f4d16d92a ]

With newer kernels that use fs_context for nfs mounts, remounts fail with
-EINVAL.

$ mount -t nfs -o nolock 10.0.0.1:/tmp/test /mnt/test/
$ mount -t nfs -o remount /mnt/test/
mount: mounting 10.0.0.1:/tmp/test on /mnt/test failed: Invalid argument

For remounts, the nfs server address and port are populated by
nfs_init_fs_context and later overwritten with 0x00 bytes by
nfs23_parse_monolithic. The remount then fails as the server address is
invalid.

Fix this by not overwriting nfs server info in nfs23_parse_monolithic if
we're doing a remount.

Fixes: f2aedb713c28 ("NFS: Add fs_context support.")
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfs/fs_context.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
index 9bcd53d5c7d46..9a5b735e74f9e 100644
--- a/fs/nfs/fs_context.c
+++ b/fs/nfs/fs_context.c
@@ -1047,9 +1047,12 @@ static int nfs23_parse_monolithic(struct fs_context *fc,
ctx->acdirmax = data->acdirmax;
ctx->need_mount = false;

- memcpy(sap, &data->addr, sizeof(data->addr));
- ctx->nfs_server.addrlen = sizeof(data->addr);
- ctx->nfs_server.port = ntohs(data->addr.sin_port);
+ if (!is_remount_fc(fc)) {
+ memcpy(sap, &data->addr, sizeof(data->addr));
+ ctx->nfs_server.addrlen = sizeof(data->addr);
+ ctx->nfs_server.port = ntohs(data->addr.sin_port);
+ }
+
if (sap->ss_family != AF_INET ||
!nfs_verify_server_address(sap))
goto out_no_address;
--
2.43.0