On Wed, 3 Jul 2013 22:27:45 +0200 mwilck@xxxxxxxx wrote:
> This patch implements the previously unsupported case where
> store_super_ddf is called with a non-empty superblock.
>
> For DDF, writing meta data to just one disk makes no sense.
> We would run the risk of writing inconsistent meta data
> to the devices. So just call __write_init_super_ddf and
> write to all devices, including the one passed by the caller.
>
> This patch assumes that the device to store the superblock on
> has already been added to the DDF structure. Otherwise, an
> error message will be emitted.
>
> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
I'm not sure I really like this. If mdadm is calling ->store_super, then it
wants to write to just one device. It will quite possibly call
->store_super on all devices, and with your change that will write to all
devices multiple times.
So maybe a different interface is needed?
What is the big-picture effect of this patch? What mdadm function now works
that didn't work before?
Thanks,
NeilBrown
> ---
> super-ddf.c | 41 +++++++++++++++++++++++++++++++++++------
> 1 files changed, 35 insertions(+), 6 deletions(-)
>
> diff --git a/super-ddf.c b/super-ddf.c
> index b806949..b3c846d 100644
> --- a/super-ddf.c
> +++ b/super-ddf.c
> @@ -3471,15 +3471,44 @@ static int store_super_ddf(struct supertype *st, int fd)
> if (!ddf)
> return 1;
>
> - /* ->dlist and ->conflist will be set for updates, currently not
> - * supported
> - */
> - if (ddf->dlist || ddf->conflist)
> - return 1;
> -
> if (!get_dev_size(fd, NULL, &dsize))
> return 1;
>
> + if (ddf->dlist || ddf->conflist) {
> + struct stat sta;
> + struct dl *dl;
> + int ofd, ret;
> +
> + if (fstat(fd, &sta) == -1 || !S_ISBLK(sta.st_mode)) {
> + pr_err("%s: file descriptor for invalid device\n",
> + __func__);
> + return 1;
> + }
> + for (dl = ddf->dlist; dl; dl = dl->next)
> + if (dl->major == (int)major(sta.st_rdev) &&
> + dl->minor == (int)minor(sta.st_rdev))
> + break;
> + if (!dl) {
> + pr_err("%s: couldn't find disk %d/%d\n", __func__,
> + (int)major(sta.st_rdev),
> + (int)minor(sta.st_rdev));
> + return 1;
> + }
> + /*
> + For DDF, writing to just one disk makes no sense.
> + We would run the risk of writing inconsistent meta data
> + to the devices. So just call __write_init_super_ddf and
> + write to all devices, including this one.
> + Use the fd passed to this function, just in case dl->fd
> + is invalid.
> + */
> + ofd = dl->fd;
> + dl->fd = fd;
> + ret = __write_init_super_ddf(st);
> + dl->fd = ofd;
> + return ret;
> + }
> +
> if (posix_memalign(&buf, 512, 512) != 0)
> return 1;
> memset(buf, 0, 512);
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