5:31 p.m.
This creates a generic partition table interface. One immediate
advantage is that you can create GPT partitions which can be larger
than 2 TB.
For example, here is a 1 exabyte partition:
<fs> sparse /mnt/tmp/test/test.img 1E
<fs> run
<fs> part-init gpt /dev/vda
<fs> part-add /dev/vda primary 0 0
<fs> list-devices
/dev/vda
<fs> list-partitions
/dev/vda1
<fs> blockdev-getsize64 /dev/vda1
1099511627775983104
Rich.
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3:16 a.m.
New subject: [PATCH VERSION 2] Generic partition creation interface.
This just tidies us the API over the previous version:
(1) part-init now takes the parameters in (device, parttype) order,
so it's consistent with the other calls.
(2) guestfs_part_bootable -> guestfs_part_set_bootable, so we can
add guestfs_part_get_bootable in future.
(3) The documentation for part-init is changed to make it clear that
only MS-DOS and GPT partition table types are supported. The others
are best-effort.
Rich.
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4:07 a.m.
New subject: [PATCH VERSION 3] Generic partition creation interface.
This adds a "part-disk" command which can be used to quickly partition
a whole disk into a single partition. Updates the tests and a recipe
to use it.
Rich.
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7:15 a.m.
New subject: [PATCH VERSION 3] Generic partition creation interface.
After a bit of discussion with Jim Meyering I've decided to withdraw
this and rewrite it based on libparted. Using the parted command line
tool is just too unpredictable.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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9:35 a.m.
New subject: [PATCH VERSION 4] Generic partition creation interface.
On Thu, Nov 05, 2009 at 01:15:03PM +0000, Richard W.M. Jones wrote:
After a bit of discussion with Jim Meyering I've decided to
withdraw
this and rewrite it based on libparted. Using the parted command line
tool is just too unpredictable.
After going down this rathole I decided maybe that wasn't such a
good plan after all.
The following patch goes back to using the command line interface, but
we have made guestfs_part_disk work for both MBR and GPT formats
(thanks to Jim).
Most of the rest of the patch is concerned with updating documentation
and examples to emphasize using guestfs_part* instead of
guestfs_sfdisk* calls.
Rich.
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10:19 a.m.
New subject: [PATCH VERSION 4] Generic partition creation interface.
Richard W.M. Jones wrote:
On Thu, Nov 05, 2009 at 01:15:03PM +0000, Richard W.M. Jones wrote:
> After a bit of discussion with Jim Meyering I've decided to withdraw
> this and rewrite it based on libparted. Using the parted command line
> tool is just too unpredictable.
After going down this rathole I decided maybe that wasn't such a
good plan after all.
The following patch goes back to using the command line interface, but
we have made guestfs_part_disk work for both MBR and GPT formats
(thanks to Jim).
Most of the rest of the patch is concerned with updating documentation
and examples to emphasize using guestfs_part* instead of
guestfs_sfdisk* calls.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine. Supports Linux and Windows.
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>From 74914b6fd255d849c8d5caf482e9c727f0a13afd Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones(a)redhat.com>
Date: Wed, 4 Nov 2009 23:15:26 +0000
Subject: [PATCH] Generic partition creation interface.
The current sfdisk interface works, but is somewhat limited
since it can only deal with MBR-style partitions. For disks
larger than 2TB, MBR partitions are unsuitable and we need
to provide access to other partition table types (eg. GPT).
Hi Rich,
This all looks fine.
Haven't tested yet, though.
Two comments:
...
+int
+do_part_add (const char *device, const char *prlogex,
+ int64_t startsect, int64_t endsect)
+{
+ char *err;
+ int r;
+ char startstr[32];
+ char endstr[32];
+
+ /* Check and translate prlogex. */
+ if (strcmp (prlogex, "primary") == 0 ||
+ strcmp (prlogex, "logical") == 0 ||
+ strcmp (prlogex, "extended") == 0)
+ ;
+ else if (strcmp (prlogex, "p") == 0)
+ prlogex = "primary";
+ else if (strcmp (prlogex, "l") == 0)
+ prlogex = "logical";
+ else if (strcmp (prlogex, "e") == 0)
+ prlogex = "extended";
+ else {
+ reply_with_error ("part-add: unknown partition type: %s: this should be
\"primary\", \"logical\" or \"extended\"", prlogex);
+ return -1;
Did you consider enforcing this only for msdos partition tables
and allowing arbitrary names for GPT?
...
+int
+do_part_disk (const char *device, const char *parttype)
+{
+ char *err;
+ int r;
+ const char *startstr;
+ const char *endstr;
+
+ parttype = check_parttype (parttype);
+ if (!parttype) {
+ reply_with_error ("part-disk: unknown partition type: common choices are
\"gpt\" and \"msdos\"");
+ return -1;
+ }
+
+ /* Voooooodooooooooo (thanks Jim Meyering for working this out). */
+ if (strcmp (parttype, "msdos") == 0) {
+ startstr = "1s";
+ endstr = "-1s";
+ } else if (strcmp (parttype, "gpt") == 0) {
+ startstr = "34s";
+ endstr = "-34s";
+ } else {
+ /* untested */
+ startstr = "1s";
+ endstr = "-1s";
+ }
+
+ r = command (NULL, &err,
+ "/sbin/parted", "-s", "--", device,
+ "mklabel", parttype,
+ /* This slightly wrong - in the GPT case it will give
+ * the partition the name "primary". We have to give
+ * it some name, so this is as good as any.
+ */
+ "mkpart", "primary", startstr, endstr,
I created many GPT partition tables with "primary" as the name
of each partition, before I noticed the error.
To avoid giving the impression that libguestfs is doing
this out of ignorance, how about using e.g.,
strcmp (parttype, "gpt") == 0 ? "p1" : "primary"
...
5:54 a.m.
New subject: [PATCH VERSION 4] Generic partition creation interface.
On Thu, Nov 05, 2009 at 05:19:33PM +0100, Jim Meyering wrote:
> +int
> +do_part_add (const char *device, const char *prlogex,
> + int64_t startsect, int64_t endsect)
> +{
> + char *err;
> + int r;
> + char startstr[32];
> + char endstr[32];
> +
> + /* Check and translate prlogex. */
> + if (strcmp (prlogex, "primary") == 0 ||
> + strcmp (prlogex, "logical") == 0 ||
> + strcmp (prlogex, "extended") == 0)
> + ;
> + else if (strcmp (prlogex, "p") == 0)
> + prlogex = "primary";
> + else if (strcmp (prlogex, "l") == 0)
> + prlogex = "logical";
> + else if (strcmp (prlogex, "e") == 0)
> + prlogex = "extended";
> + else {
> + reply_with_error ("part-add: unknown partition type: %s: this should be
\"primary\", \"logical\" or \"extended\"", prlogex);
> + return -1;
Did you consider enforcing this only for msdos partition tables
and allowing arbitrary names for GPT?
This is a bit tricky from the API point of view. If we were
going to allow names too, we'd want something like:
guestfs_part_add (g, device, prlogex, name, startsect, endsect);
with name being an optional string and we'd have to enforce that the
string is not set for msdos and set for gpt. Of course in
guestfs_part_add we don't know the partition table type, unless we
saved it from an earlier call or look it up, both of which are hairy.
It's even worse though:
$ parted -s /tmp/test.img -- \
mklabel gpt \
mkpart primary 34s 256s \
mkpart primary 257s -34s
$ parted /tmp/test.img print
WARNING: You are not superuser. Watch out for permissions.
Model: (file)
Disk /tmp/test.img: 10.5MB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
1 17.4kB 132kB 114kB primary
2 132kB 10.5MB 10.3MB primary
We've now got two GPT partitions named "primary". (At least parted
allows this and doesn't barf).
The undocumented name feature of parted mkpart is a minefield ...
I've now added a guestfs_part_set_name call to the API [patch to
follow] so at least people can change the name later.
[in do_part_disk]
I created many GPT partition tables with "primary" as the
name
of each partition, before I noticed the error.
To avoid giving the impression that libguestfs is doing
this out of ignorance, how about using e.g.,
strcmp (parttype, "gpt") == 0 ? "p1" : "primary"
I agree in the guestfs_part_disk case we can do better because we do
know the partition name, so this is a very sensible change.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v
11:52 a.m.
New subject: [PATCH VERSION 5 FOR DISCUSSION ONLY] Generic partition creation interface.
** NOT TO BE PUSHED ** This doesn't quite work at the moment. All the
tests pass, except: test_list_partitions_0 wipes the disk and creates
a single partition covering the whole disk. However the test fails
because it thinks the disk has 3 partitions. At the moment I have no
idea why it would think this.
Anyway, the patch has evolved further:
(1) guestfs_set_part_name can be used to set the name of a partition.
(2) In guestfs_part_disk, if GPT set the partition name to "p1". But
in guestfs_part_add we still have the bug that the partition name is
set to "primary" for GPT partition tables. At least this is now
documented as a bug.
(3) Work around an apparent bug in parted where it fails to do
ioctl(BLKRRPART) [re-read the partition table], by catching this case
and rereading the partition table ourselves.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://et.redhat.com/~rjones/libguestfs/
See what it can do: http://et.redhat.com/~rjones/libguestfs/recipes.html
3:08 a.m.
New subject: [PATCH VERSION 5 FOR DISCUSSION ONLY] Generic partition creation interface.
Richard W.M. Jones wrote:
...
(3) Work around an apparent bug in parted where it fails to do
ioctl(BLKRRPART) [re-read the partition table], by catching this case
and rereading the partition table ourselves.
Hi Rich,
I haven't looked at that patch yet, but this part rings big bells:
parted-2.0+ (not yet in rawhide) has had significant changes in this area.
7:12 a.m.
New subject: [PATCH VERSION 6] Generic partition creation interface.
I think this patch is looking in good shape to be reviewed and applied
now.
On Mon, Nov 09, 2009 at 10:08:32AM +0100, Jim Meyering wrote:
Richard W.M. Jones wrote:
...
> (3) Work around an apparent bug in parted where it fails to do
> ioctl(BLKRRPART) [re-read the partition table], by catching this case
> and rereading the partition table ourselves.
Hi Rich,
I haven't looked at that patch yet, but this part rings big bells:
parted-2.0+ (not yet in rawhide) has had significant changes in this area.
The workaround should be safe, in that it looks for the specific error
string that parted 1.9 throws and tries to reread the partition table.
Rereading the partition table is always safe, even if we do it at the
wrong time.
> ** NOT TO BE PUSHED ** This doesn't quite work at the
moment. All the
> tests pass, except: test_list_partitions_0 wipes the disk and creates
> a single partition covering the whole disk. However the test fails
> because it thinks the disk has 3 partitions. At the moment I have no
> idea why it would think this.
If this is still a problem, let me know and I'll take a look.
This fixed itself. That's the sort of bug I like.
Rich.
--
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3:11 a.m.
New subject: [PATCH VERSION 5 FOR DISCUSSION ONLY] Generic partition creation interface.
Richard W.M. Jones wrote:
** NOT TO BE PUSHED ** This doesn't quite work at the moment.
All the
tests pass, except: test_list_partitions_0 wipes the disk and creates
a single partition covering the whole disk. However the test fails
because it thinks the disk has 3 partitions. At the moment I have no
idea why it would think this.
If this is still a problem, let me know and I'll take a look.
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