From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH][RFC] Emulate BLKRRPART on device-mapper Date: Wed, 22 Jul 2009 09:06:08 +0200 Message-ID: <4A66BA60.2020500@suse.de> References: <200907081414.50698.knikanth@suse.de> <20090720182324.GD32330@agk-dp.fab.redhat.com> <4A65E912.6020706@redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <4A65E912.6020706@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Milan Broz Cc: Nikanth Karthikesan , device-mapper development , Alasdair G Kergon , Jens Axboe List-Id: dm-devel.ids Milan Broz wrote: > Alasdair G Kergon wrote: >> On Wed, Jul 08, 2009 at 02:14:50PM +0530, Nikanth Karthikesan wrote: >> =20 >>> From: Hannes Reinecke >>> Subject: Emulate BLKRRPART on device-mapper >>> >>> Partitions on device-mapper devices are managed by kpartx (if at >>> all). So if we were just to send out a 'change' event if someone >>> called BLKRRPART on these devices, kpartx will be triggered via udev >>> and can manage the partitions accordingly. >>> >>> =20 >> Please could I have a 'Tested-by' for this one? >> =20 > I am afraid that this patch cannot work, BLRRPART never reach this code= . > I tried another idea - or is there better way how to achieve that? >=20 Hey, that is cool. And what's more, that's exactly what I need for anothe= r pet-project of mine, switching off the in-kernel partitioning code altoge= ther. But there are some comments, see below. > Milan > --- >=20 > From: Milan Broz >=20 > Add genhd flag requesting notification of partition changes only. >=20 > This patch provides notification mechanism which allows handle partitio= n > code in userspace. >=20 > If the BLKRRPART ioctl arrives and GENHD_FL_PARTITION_CHANGE_NOTIFY > is set, just send uevent and ignore in-kernel partitioning code. >=20 > This is useful e.g. for device-mapper devices, which can use kpartx > or similar tool in udev rules. >=20 > Signed-off-by: Milan Broz > --- > block/ioctl.c | 3 ++- > drivers/md/dm.c | 1 + > fs/partitions/check.c | 6 ++++++ > include/linux/genhd.h | 8 ++++++++ > 4 files changed, 17 insertions(+), 1 deletions(-) >=20 > diff --git a/block/ioctl.c b/block/ioctl.c > index 500e4c7..bce793f 100644 > --- a/block/ioctl.c > +++ b/block/ioctl.c > @@ -101,7 +101,8 @@ static int blkdev_reread_part(struct block_device *= bdev) > struct gendisk *disk =3D bdev->bd_disk; > int res; > =20 > - if (!disk_partitionable(disk) || bdev !=3D bdev->bd_contains) > + if (!disk_userspace_partitions(disk) && > + (!disk_partitionable(disk) || bdev !=3D bdev->bd_contains)) > return -EINVAL; > if (!capable(CAP_SYS_ADMIN)) > return -EACCES; > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > index 9acd54a..1186ce1 100644 > --- a/drivers/md/dm.c > +++ b/drivers/md/dm.c > @@ -1791,6 +1791,7 @@ static struct mapped_device *alloc_dev(int minor) > md->disk->queue =3D md->queue; > md->disk->private_data =3D md; > sprintf(md->disk->disk_name, "dm-%d", minor); > + md->disk->flags |=3D GENHD_FL_PARTITION_CHANGE_NOTIFY; > add_disk(md->disk); > format_dev_t(md->name, MKDEV(_major, minor)); > =20 > diff --git a/fs/partitions/check.c b/fs/partitions/check.c > index ea4e6cb..bb42c44 100644 > --- a/fs/partitions/check.c > +++ b/fs/partitions/check.c > @@ -521,6 +521,12 @@ int rescan_partitions(struct gendisk *disk, struct= block_device *bdev) > struct parsed_partitions *state; > int p, highest, res; > =20 > + /* partitions handled in userspace, just send change event */ > + if (disk_userspace_partitions(disk)) { > + kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE); > + return 0; > + } > + Wrong. If you do it here, you'll never be able to catch any size changes of the disk. You'll have to move it to after the 'bdev->bd_invalidated =3D= 0' line. > if (bdev->bd_part_count) > return -EBUSY; > res =3D invalidate_partition(disk, 0); > diff --git a/include/linux/genhd.h b/include/linux/genhd.h > index 45fc320..a241bd6 100644 > --- a/include/linux/genhd.h > +++ b/include/linux/genhd.h > @@ -116,6 +116,9 @@ struct hd_struct { > #define GENHD_FL_EXT_DEVT 64 /* allow extended devt */ > #define GENHD_FL_NATIVE_CAPACITY 128 > =20 > +/* notify udev instead of use in-kernel partitioning */ > +#define GENHD_FL_PARTITION_CHANGE_NOTIFY 256 > + I would suggest renaming it to GENHD_FL_USERSPACE_PARTITIONS, as this is more in line with the function of the flag. Plus I have a patch making use of it :-) I'll send an adapted patchset. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: Markus Rex, HRB 16746 (AG N=FCrnberg)