On Sun, 2024-04-14 at 19:01 +0200, Martin Kaiser wrote:
> 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>
> ---
> 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 linux-next. 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;
Doesn't nfs4_parse_monolithic need the same fix?
--
Jeff Layton <jlayton@xxxxxxxxxx>
