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@xxxxxxxxx>
---
v4:
- rebased against linux-next from 20th May 2024
v3:
- rebased against linux-next from 12th April 2024
v2:
- rebased against linux-next from 26th February 2024
Dear all,
I'm resending this patch again.
The problem that I'm trying to fix is still present in today's linux-next.
It affects (amongst others) systems where the rootfs is mounted via nfs2/3.
If the rootfs is mounted read-only first and remounted read-write later, the
remount will fail and the system won't boot.
Thanks in advance for any reviews and comments.
I guess that we're taking this path for remounts
do_remount
fs_context_for_reconfigure
alloc_fs_context
init_fs_context == nfs_init_fs_context
fc->root is set for remounts
ctx->nfs_server is populated
parse_monolithic_mount_data
nfs_fs_context_parse_monolithic
nfs23_parse_monolithic
ctx->nfs_server is overwritten with data from mount request
An alternative to checking for !is_remount_fc(fc) would be to check
if (ctx->nfs_server.addrlen == 0)
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 d0a0956f8a13..cac1157be2c2 100644
--- a/fs/nfs/fs_context.c
+++ b/fs/nfs/fs_context.c
@@ -1112,9 +1112,12 @@ 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;
--
2.39.2
