@@ -477,12 +477,16 @@ 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;
+ if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
+ /*
+ * Ignore options coming from mount(MS_REMOUNT) for backward
+ * compatibility.
+ */
+ if (fc->oldapi)
+ return 0;
+
+ return invalfc(fc, "No changes allowed in reconfigure");
+ }
opt = fs_parse(fc, fuse_fs_parameters, param, &result);
if (opt < 0)
@@ -2603,6 +2603,7 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
if (IS_ERR(fc))
return PTR_ERR(fc);
+ fc->oldapi = true;
err = parse_monolithic_mount_data(fc, data);
if (!err) {
down_write(&sb->s_umount);
@@ -109,6 +109,7 @@ struct fs_context {
enum fs_context_phase phase:8; /* The phase the context is in */
bool need_free:1; /* Need to call ops->free() */
bool global:1; /* Goes into &init_user_ns */
+ bool oldapi:1; /* Coming from mount(2) */
};
struct fs_context_operations {
Previous patch changed handling of remount/reconfigure to ignore all options, including those that are unknown to the fuse kernel fs. This was done for backward compatibility, but this likely only affects the old mount(2) API. The new fsconfig(2) based reconfiguration could possibly be improved. This would make the new API less of a drop in replacement for the old, OTOH this is a good chance to get rid of some weirdnesses in the old API. Several other behaviors might make sense: 1) unknown options are rejected, known options are ignored 2) unknown options are rejected, known options are rejected if the value is changed, allowed otherwise 3) all options are rejected Prior to the backward compatibility fix to ignore all options all known options were accepted (1), even if they change the value of a mount parameter; fuse_reconfigure() does not look at the config values set by fuse_parse_param(). To fix that we'd need to verify that the value provided is the same as set in the initial configuration (2). The major drawback is that this is much more complex than just rejecting all attempts at changing options (3); i.e. all options signify initial configuration values and don't make sense on reconfigure. This patch opts for (3) with the rationale that no mount options are reconfigurable in fuse. Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> --- fs/fuse/inode.c | 16 ++++++++++------ fs/namespace.c | 1 + include/linux/fs_context.h | 1 + 3 files changed, 12 insertions(+), 6 deletions(-)