Hey there!
i sent the patch below ~10 days ago and did not receive any feedback
whatsoever. if it's wrong or deemed unneeded, i'd really like to hear
your opinion why. thanks!
On Thu, 10 Feb 2011 19:02:05 +0100
Stefan Tauner <stefan.tauner@xxxxxxxxxxxxxxxxxxxx> wrote:
> Hello,
>
> the linux kernel ignores (some?) options when they are used in bind
> mounts. Because of this 'mount' issues a warning if bind mounting with
> the ro option results in a writable mount (since 2009).
> From my point of view this is an error in the kernel because it does
> not report that and should be fixed. Nevertheless since mount already
> checks for this failure it is not a big change to just retry with the
> MS_REMOUNT flag added, which normally should succeed. If not we can
> still warn as before. This would allow using "bind,ro" in /etc/fstab.
> The patch below implements that.
>
> (please cc me)
>
> Signed-off-by: Stefan Tauner <stefan.tauner@xxxxxxxxxxxxxxxxxxxx>
> ---
> mount/mount.c | 14 +++++++++-----
> 1 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/mount/mount.c b/mount/mount.c
> index f5b3521..28a05f9 100644
> --- a/mount/mount.c
> +++ b/mount/mount.c
> @@ -1655,14 +1655,18 @@ try_mount_one (const char *spec0, const char
> *node0, const char *types0, }
>
> /* Kernel allows to use MS_RDONLY for bind mounts, but the
> read-only request
> - * could be silently ignored. Check it to avoid 'ro' in mtab and
> 'rw' in
> - * /proc/mounts.
> + * could be silently ignored. Check that and retry with MS_REMOUNT
> once. If it
> + * is still rw honor it to avoid 'ro' in mtab and 'rw'
> in /proc/mounts. */
> if (!fake && mnt5_res == 0 &&
> (flags & MS_BIND) && (flags & MS_RDONLY)
> && !is_readonly(node)) { -
> - printf(_("mount: warning: %s seems to be mounted
> read-write.\n"), node);
> - flags &= ~MS_RDONLY;
> + if (!(flags & MS_REMOUNT)) {
> + flags |= MS_REMOUNT;
> + goto mount_retry;
> + } else {
> + printf(_("mount: warning: %s seems to be mounted
> read-write.\n"), node);
> + flags &= ~MS_RDONLY;
> + }
> }
>
> /* Kernel can silently add MS_RDONLY flag when mounting file
> system that
--
Kind regards/Mit freundlichen Grüßen, Stefan Tauner
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