> > Maybe instead of messing with masks, it's better to introduce a
> > get_flags() or a more general mount_stat() operation, and let
> > userspace deal with setting and clearing flags, just as we do for
> > stat/chmod?
> >
> > So we'd have
> >
> > mount_stat(path, stat);
> > mount_bind(from, to, flags);
> > mount_set_flags(path, flags);
> > mount_move(from, to);
> >
> > and perhaps
> >
> > mount_remount(path, opt_string, flags);
>
> Sounds reasonable to me. But it wouldn't directly solve the "do a
> recursive bind mount setting the MS_READONLY flag on all children"
> problem, so we'd need some of the earlier suggestions too.
Doh, you're right.
Let's try the original idea, but a bit cleaner:
/* flags: */
#define MNT_CTRL_RECURSE (1 << 0)
/* mnt_flags: */
#define MNT_NOSUID 0x01
#define MNT_NODEV 0x02
#define MNT_NOEXEC 0x04
#define MNT_NOATIME 0x08
#define MNT_NODIRATIME 0x10
#define MNT_RELATIME 0x20
#define MNT_SHARED 0x1000
#define MNT_UNBINDABLE 0x2000
#define MNT_PNODE_MASK 0x3000
struct mount_param {
u64 flags; /* control flags */
u64 mnt_flags; /* new mount flags */
u64 mnt_flags_mask; /* mask for new mount flags */
};
int mount_bindat(int fromfd, const char *frompath,
int tofd, const char *topath,
struct mount_param *param);
int mount_setflagsat(int fd, const char *path,
struct mount_param *param);
int mount_moveat(int fromfd, const char *frompath,
int tofd, const char *topath);
...
I deliberately not used the MS_* flags, which is currently a messy mix
of things with totally different meanings.
Does this solve all the issues?
Miklos
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