The command
mount -o remount -o unknownoption /mnt/fuse
succeeds on kernel versions prior to v5.4 and fails on kernel version at or after. This is because fuse_parse_param() rejects any unrecognised options in case of FS_CONTEXT_FOR_RECONFIGURE, just as for FS_CONTEXT_FOR_MOUNT.
This causes a regression in case the fuse filesystem is in fstab, since remount sends all options found there to the kernel; even ones that are meant for the initial mount and are consumed by the userspace fuse server.
Fix this by ignoring mount options, just as fuse_remount_fs() did prior to the conversion to the new API.
Reported-by: Stefan Priebe s.priebe@profihost.ag Fixes: c30da2e981a7 ("fuse: convert to use the new mount API") Cc: stable@vger.kernel.org # v5.4 Signed-off-by: Miklos Szeredi mszeredi@redhat.com --- fs/fuse/inode.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index be39dff57c28..ba201bf5ffad 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -477,6 +477,13 @@ static int fuse_parse_param(struct fs_context *fc, struct fs_parameter *param) struct fuse_fs_context *ctx = fc->fs_private; int opt;
+ /* + * Ignore options coming from mount(MS_REMOUNT) for backward + * compatibility. + */ + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) + return 0; + opt = fs_parse(fc, fuse_fs_parameters, param, &result); if (opt < 0) return opt;