On Tue, Feb 22, 2022 at 06:59:10PM +0000, Ritika Srivastava wrote: > On 2/22/22, 10:28 AM, "Benjamin Marzinski" wrote: > > On Fri, Feb 11, 2022 at 12:41:48PM -0800, Ritika Srivastava wrote: > >> Add -P, partition scanning option to kpartx which would set > >> LO_FLAGS_PARTSCAN flag during loop device creation. > >> This option is same as losetup -P option. > > >I'm confused here. What's the benefit of doing this? Doesn't this create > >partition devices, just like kpartx would? > > This enables partition scanning for loop devices created via kpartx. > When enabled, LO_FLAGS_PARTSCAN flag will be set during loop creation via kpartx -a. > On detach (kpartx -d), any partitions (/dev/loopXpY) would also be removed. > It has similar use cases as losetup -P option. > > Currently, kpartx does not create partition loop devices (/dev/loopXpY) via kpartx -a And I'm trying to figure out why you want to create /dev/loop0p1 if you already have /dev/mapper/loop0p1? The ability of kpartx to create partitioned loop devices predates the existance "kpartx -P". So perhaps the better question is, why do you want to run # kpartx -av test.img instead of just running # loasetup -fP test.img They both get you partition devices, and you don't need both of them. Or do you, for some reason I don't understand? -Ben > Example: > 1. Current behavior: kpartx -a does not create /dev/loop0p1 > > # kpartx -av test.img > add map loop0p1 (252:0): 0 99937 linear /dev/loop0 64 > > (Notice below: /dev/loop0p1 NOT created) > # ls -l /dev/loop0* > brw-rw----. 1 root disk 7, 0 Jan 14 20:46 /dev/loop0 > > 2. IF -P IS USED to create loop device, /dev/loop0p1 IS created. > > # kpartx -av -P test.img > add map loop0p1 (252:0): 0 99937 linear /dev/loop0 64 > > (Notice below: /dev/loop0p1 IS created) > # ls -l /dev/loop0* > brw-rw----. 1 root disk 7, 0 Jan 14 20:50 /dev/loop0 > brw-rw----. 1 root disk 259, 0 Jan 14 20:50 /dev/loop0p1 > > > Similar behavior can also be observed during detach > 1. Current Behavior: kpartx -d does NOT delete partitions > > # kpartx -a -v test.img > # parted -a none -s /dev/loop0 mkpart primary 64s 100000s > > # ls -l /dev/loop0* > brw-rw----. 1 root disk 7, 0 Jan 14 20:54 /dev/loop0 > brw-rw----. 1 root disk 259, 0 Jan 14 20:54 /dev/loop0p1 > > # kpartx -d test.img > loop deleted : /dev/loop0 > > (Notice: /dev/loop0p1 NOT deleted) > # ls -l /dev/loop0* > brw-rw----. 1 root disk 7, 0 Jan 14 20:54 /dev/loop0 > brw-rw----. 1 root disk 259, 0 Jan 14 20:54 /dev/loop0p1 > > 2. IF -P IS added while creating loop, kpartx -d DOES delete loop0p1 > > # kpartx -a -v -P test.img > # parted -a none -s /dev/loop0 mkpart primary 64s 100000s > > # ls -l /dev/loop0* > brw-rw----. 1 root disk 7, 0 Jan 14 20:46 /dev/loop0 > brw-rw----. 1 root disk 259, 0 Jan 14 20:46 /dev/loop0p1 > > # kpartx -d test.img > loop deleted : /dev/loop0 > > (Notice: /dev/loop0p1 IS deleted) > # ls -l /dev/loop0* > brw-rw----. 1 root disk 7, 0 Jan 14 20:46 /dev/loop0 > > Thanks, > Ritika > > > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
