[Libguestfs] [PATCH v2 1/5] uuid: add support to change uuid of btrfs partition
Chen, Hanxiao
chenhanxiao at cn.fujitsu.com
Thu Jun 25 09:49:58 UTC 2015
Hi, Pino
> -----Original Message-----
> From: libguestfs-bounces at redhat.com [mailto:libguestfs-bounces at redhat.com] On
> Behalf Of Pino Toscano
> Sent: Wednesday, June 24, 2015 6:16 PM
> To: libguestfs at redhat.com
> Subject: Re: [Libguestfs] [PATCH v2 1/5] uuid: add support to change uuid of btrfs
> partition
>
> In data mercoledì 24 giugno 2015 15:54:03, Chen Hanxiao ha scritto:
> > btrfs-progs v4.1 add support to change uuid of btrfs fs.
> >
> > Signed-off-by: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>
> > ---
> > v2: put btrfs operation back to daemon/btrfs.c
> > move tests to tests/btrfs
> >
> > daemon/btrfs.c | 60 ++++++++++++++++++++++++++++++++++++++++++
> > daemon/daemon.h | 1 +
> > daemon/uuids.c | 9 +++++--
> > tests/btrfs/test-btrfs-misc.pl | 6 +++++
> > 4 files changed, 74 insertions(+), 2 deletions(-)
> >
> > diff --git a/daemon/btrfs.c b/daemon/btrfs.c
> > index 20e5e6b..b82c1b9 100644
> > --- a/daemon/btrfs.c
> > +++ b/daemon/btrfs.c
> > @@ -790,6 +790,44 @@ do_btrfs_device_delete (char *const *devices, const char
> *fs)
> > return 0;
> > }
> >
> > +
> > +/* btrfstune command add two new options
> > + * -U UUID change fsid to UUID
> > + * -u change fsid, use a random one
> > + * since v4.1
> > + * We could check wheter 'btrfstune' support
> > + * '-u' and '-U UUID' option by checking the output of
> > + * 'btrfstune' command.
> > + */
> > +static int
> > +test_btrftune_uuid_opt (void)
> > +{
> > + static int result = -1;
> > + if (result != -1)
> > + return result;
> > +
> > + CLEANUP_FREE char *err = NULL;
> > +
> > + int r = commandr (NULL, &err, str_btrfstune, NULL);
> > +
> > + if (r == -1) {
> > + reply_with_error ("btrfstune: %s", err);
> > + return -1;
> > + }
> > +
> > + /* FIXME currently btrfstune do not support '--help'.
> > + * If got an invalid options, it will print its usage
> > + * in stderr.
> > + * We had to check it there.
> > + */
> > + if (strstr (err, "-U") == NULL || strstr (err, "-u") == NULL)
> > + result = 0;
> > + else
> > + result = 1;
> > +
> > + return result;
> > +}
> > +
> > int
> > do_btrfs_set_seeding (const char *device, int svalue)
> > {
> > @@ -807,6 +845,28 @@ do_btrfs_set_seeding (const char *device, int svalue)
> > return 0;
> > }
> >
> > +int
> > +btrfstune_set_uuid (const char *device, const char *uuid)
>
> Call it btrfs_set_uuid please, as the fact that it uses btrfstune is an
> implementation detail of it.
>
> > +{
> > + CLEANUP_FREE char *err = NULL;
> > + int r;
> > + int has_uuid_opts = test_btrftune_uuid_opt ();
> > +
> > + if (has_uuid_opts == 0) {
>
> Check for <= 0 here, to consider errors in test_btrftune_uuid_opt
> on the safe side.
>
> > + reply_with_error ("btrfstune do not support '-u'");
>
> reply_with_error ("btrfs filesystems' UUID cannot be changed");
How about:
errcode = ENOTSUP;
reply_with_error_errno (errcode, " btrfs filesystems' UUID cannot be changed");
Then we got the errno, and set_uuid could tell whether we support this feature.
Regards,
- Chen
>
> > + return -1;
> > + }
> > +
> > + r = commandr (NULL, &err, str_btrfstune, "-f", "-U", uuid, device, NULL);
> > +
> > + if (r == -1) {
> > + reply_with_error ("%s: %s", device, err);
> > + return -1;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > /* Takes optional arguments, consult optargs_bitmask. */
> > int
> > do_btrfs_fsck (const char *device, int64_t superblock, int repair)
> > diff --git a/daemon/daemon.h b/daemon/daemon.h
> > index 136e9a9..ee0c96f 100644
> > --- a/daemon/daemon.h
> > +++ b/daemon/daemon.h
> > @@ -268,6 +268,7 @@ extern char *debug_bmap_device (const char *subcmd, size_t
> argc, char *const *co
> >
> > /*-- in btrfs.c --*/
> > extern char *btrfs_get_label (const char *device);
> > +extern int btrfstune_set_uuid (const char *device, const char *uuid);
> >
> > /*-- in ntfs.c --*/
> > extern char *ntfs_get_label (const char *device);
> > diff --git a/daemon/uuids.c b/daemon/uuids.c
> > index 06b33e9..f7791ab 100644
> > --- a/daemon/uuids.c
> > +++ b/daemon/uuids.c
> > @@ -91,6 +91,12 @@ swapuuid (const char *device, const char *uuid)
> > return 0;
> > }
> >
> > +static int
> > +btrfsuuid (const char *device, const char *uuid)
> > +{
> > + return btrfstune_set_uuid (device, uuid);
> > +}
>
> What is this wrapper for? Just call btrfs_set_uuid below.
>
> > int
> > do_set_uuid (const char *device, const char *uuid)
> > {
> > @@ -111,8 +117,7 @@ do_set_uuid (const char *device, const char *uuid)
> > r = swapuuid (device, uuid);
> >
> > else if (STREQ (vfs_type, "btrfs")) {
> > - reply_with_error ("btrfs filesystems' UUID cannot be changed");
> > - r = -1;
> > + r = btrfsuuid (device, uuid);
> > }
>
> Minor style note: curly brackets can be removed now.
>
> > else {
> > diff --git a/tests/btrfs/test-btrfs-misc.pl b/tests/btrfs/test-btrfs-misc.pl
> > index 2fe7c59..cd60990 100755
> > --- a/tests/btrfs/test-btrfs-misc.pl
> > +++ b/tests/btrfs/test-btrfs-misc.pl
> > @@ -47,5 +47,11 @@ my $label = $g->vfs_label ("/dev/sda1");
> > die "unexpected label: expecting 'newlabel' but got '$label'"
> > unless $label eq "newlabel";
> >
> > +# Setting btrfs UUID
> > +$g->set_uuid ("/dev/sda1", "12345678-1234-1234-1234-123456789012");
> > +my $uuid = $g->vfs_uuid ("/dev/sda1");
> > +die "unexpected label: expecting 'newlabel' but got '$uuid'"
> > + unless $uuid eq "12345678-1234-1234-1234-123456789012";
> > +
>
> Ignoring the "newlabel" copy&paste error: this code has the same issue
> as the old test added to the action tests in generator/actions.ml.
> That is, if btrfs-tools < 4.1 is used, then the test will fail (instead
> of being skipped).
>
> Thinking further about it: it might be better to make set_uuid return
> ENOTSUP for all the unsupported filesystems (including older
> btrfs-tools case). This way, the perl snippet above could check, when
> set_uuid fails, for the last_errno() and consider that a hard failure
> if it was different than ENOTSUP. Something like (untested):
>
> eval {
> $g->set_uuid (...);
> };
> my $err = $g->last_errno ();
> if ($err == 0) {
> my $uuid = $g->vfs_uuid (...);
> die ...
> } elsif ($err != Errno::ENOTSUP()) {
> die $@
> }
>
> --
> Pino Toscano
>
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