On Tue, Sep 22, 2015 at 03:24:51PM +0300, Mika Eloranta wrote:
> Usage: mkfs.xfs -m uuid=<uuid> <device>
>
> The filesystem UUID can now be optionally specified during filesystem
> creation. The default behavior is still to generate a random UUID.
>
> Allows using pre-generated UUIDs for identifying a filesystem based
> on the metadata stored inside the filesystem. Filesystem labels can
> be used for the same purpose, but are limited by their length
> (12 chars in the case of xfs) whereas the UUID field can store an
> entire 128bit UUID, which is plenty for e.g. random ID collision
> avoidance.
>
> Random UUID generated during the creation of the filesystem is not
> always feasible when an external DB or other system is used to track
> the created filesystem, e.g. in automated VM provisioning systems,
> as this would require a feedback mechanism which is not always
> available. In these cases the best approach often is to generate
> a random UUID for the filesystem before the filesystem even exists,
> store it in the tracking DB and later create the filesystem directly
> with the correct UUID (instead of "mkfs.xfs + xfs_admin -U <new_uuid>").
Much nicer! Just needs a signed-off-by tag now...
> @@ -948,6 +950,7 @@ main(
> bool finobtflag;
> int spinodes;
>
> + platform_uuid_clear(&uuid);
> progname = basename(argv[0]);
> setlocale(LC_ALL, "");
> bindtextdomain(PACKAGE, LOCALEDIR);
You can just call platform_uuid_generate(&uuid) here.
> @@ -1488,6 +1491,12 @@ main(
> finobt = c;
> finobtflag = true;
> break;
> + case M_UUID:
> + if (!value || *value == '\0')
> + reqval('m', mopts, M_UUID);
> + if (platform_uuid_parse(value, &uuid))
> + illegal(optarg, "m uuid");
> + break;
This will overwrite the pre-generated uuid if it is specified.
> default:
> unknown('m', value);
> }
> @@ -2550,7 +2559,9 @@ _("size %s specified for log subvolume is too large, maximum is %lld blocks\n"),
> sbp->sb_dblocks = dblocks;
> sbp->sb_rblocks = rtblocks;
> sbp->sb_rextents = rtextents;
> - platform_uuid_generate(&uuid);
> + if (platform_uuid_is_null(&uuid)) {
> + platform_uuid_generate(&uuid);
> + }
And this code can go away completely as we are guaranteed to have a
valid uuid by this point.
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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