On Thu, Oct 31, 2019 at 10:56:04AM +1100, NeilBrown wrote:
> If you have a RAID0 array with varying sized devices
> on a kernel before 5.4, you cannot assembling it on
> 5.4 or later without explicitly setting the layout.
> This is now possible with
> --update=layout-original (For 3.13 and earlier kernels)
> or
> --update=layout-alternate (for 3.15 and later kernels)
s/3.15/3.14/
> Signed-off-by: NeilBrown <neilb@xxxxxxx>
> ---
> Assemble.c | 8 ++++++++
> md.4 | 7 +++++++
> mdadm.8.in | 17 +++++++++++++++++
> mdadm.c | 4 ++++
> super1.c | 12 +++++++++++-
> 5 files changed, 47 insertions(+), 1 deletion(-)
>
> diff --git a/Assemble.c b/Assemble.c
> index b2e69144f1a2..4066f93e977f 100644
> --- a/Assemble.c
> +++ b/Assemble.c
> @@ -1031,6 +1031,11 @@ static int start_array(int mdfd,
> pr_err("failed to add %s to %s: %s\n",
> devices[j].devname, mddev,
> strerror(errno));
> + if (errno == EINVAL && content->array.level == 0 &&
> + content->array.layout != 0) {
> + cont_err("Possibly your kernel doesn't support RAID0 layouts.\n");
Why possibly?
> + cont_err("Please upgrade.\n");
> + }
> if (i < content->array.raid_disks * 2 ||
> i == bestcnt)
> okcnt--;
> @@ -1220,6 +1225,9 @@ static int start_array(int mdfd,
> return 0;
> }
> pr_err("failed to RUN_ARRAY %s: %s\n", mddev, strerror(errno));
> + if (errno == 524 /* ENOTSUP */ &&
> + content->array.level == 0 && content->array.layout == 0)
> + cont_err("Pleasse use --update=layout-original or --update=layout=alternate\n");
s/Pleasse/Please/
s/layout=alternate/layout-alternate/
>
> if (!enough(content->array.level, content->array.raid_disks,
> content->array.layout, 1, avail))
> diff --git a/md.4 b/md.4
> index 6fe275541abd..0712af255dd5 100644
> --- a/md.4
> +++ b/md.4
> @@ -208,6 +208,13 @@ array,
> will record the chosen layout in the metadata in a way that allows newer
> kernels to assemble the array without needing a module parameter.
>
> +To assemble an old array on a new kernel without using the module parameter,
> +use either the
> +.B "--update=layout-original"
> +option or the
> +.B "--update=layout-alternate"
> +option.
> +
> .SS RAID1
>
> A RAID1 array is also known as a mirrored set (though mirrors tend to
> diff --git a/mdadm.8.in b/mdadm.8.in
> index ea07c429e668..7240d461bdc9 100644
> --- a/mdadm.8.in
> +++ b/mdadm.8.in
> @@ -1213,6 +1213,8 @@ argument given to this flag can be one of
> .BR no\-bbl ,
> .BR ppl ,
> .BR no\-ppl ,
> +.BR layout\-original ,
> +.BR layout\-alternate ,
> .BR metadata ,
> or
> .BR super\-minor .
> @@ -1364,6 +1366,21 @@ The
> .B no\-ppl
> option will disable PPL in the superblock.
>
> +The
> +.B layout\-original
> +and
> +.B layout\-alternate
> +options are for RAID0 arrays is use before Linux 5.4. If the array was being
s/is use/in use/
> +used with Linux 3.13 or earlier, then the assemble the array on a new kernel,
s/then the/then to/
> +.B \-\-update=layout\-original
> +must be given. If the array was created and used with a kernel from Linux 3.14 to
> +Linux 5.3, then
> +.B \-\-update=layout\-alternate
> +must be given. This only needs to be given once. Subsequent assembly of the array
> +will happen normally.
> +For more information, so
see?
> +.IR md (4).
> +
Cheers!
-dann
> .TP
> .BR \-\-freeze\-reshape
> Option is intended to be used in start-up scripts during initrd boot phase.
> diff --git a/mdadm.c b/mdadm.c
> index e438f9c864da..256a97ef07f5 100644
> --- a/mdadm.c
> +++ b/mdadm.c
> @@ -795,6 +795,9 @@ int main(int argc, char *argv[])
> continue;
> if (strcmp(c.update, "revert-reshape") == 0)
> continue;
> + if (strcmp(c.update, "layout-original") == 0 ||
> + strcmp(c.update, "layout-alternate") == 0)
> + continue;
> if (strcmp(c.update, "byteorder") == 0) {
> if (ss) {
> pr_err("must not set metadata type with --update=byteorder.\n");
> @@ -825,6 +828,7 @@ int main(int argc, char *argv[])
> " 'summaries', 'homehost', 'home-cluster', 'byteorder', 'devicesize',\n"
> " 'no-bitmap', 'metadata', 'revert-reshape'\n"
> " 'bbl', 'no-bbl', 'force-no-bbl', 'ppl', 'no-ppl'\n"
> + " 'layout-original', 'layout-alternate'\n"
> );
> exit(outf == stdout ? 0 : 2);
>
> diff --git a/super1.c b/super1.c
> index 312303fecbe1..d8f4403f0388 100644
> --- a/super1.c
> +++ b/super1.c
> @@ -1550,7 +1550,17 @@ static int update_super1(struct supertype *st, struct mdinfo *info,
> sb->devflags |= FailFast1;
> else if (strcmp(update, "nofailfast") == 0)
> sb->devflags &= ~FailFast1;
> - else
> + else if (strcmp(update, "layout-original") == 0 ||
> + strcmp(update, "layout-alternate") == 0) {
> + if (__le32_to_cpu(sb->level) != 0) {
> + pr_err("%s: %s only supported for RAID0\n",
> + devname?:"", update);
> + rv = -1;
> + } else {
> + sb->feature_map |= __cpu_to_le32(MD_FEATURE_RAID0_LAYOUT);
> + sb->layout = __cpu_to_le32(update[7] == 'o' ? 1 : 2);
> + }
> + } else
> rv = -1;
>
> sb->sb_csum = calc_sb_1_csum(sb);
>
>
