Messages in this thread | | | From | Nick Piggin <> | Subject | Re: [PATCH] Modify loop device to be able to manage partitions of the disk image | Date | Thu, 6 Mar 2008 20:57:50 +1100 |
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On Thursday 06 March 2008 20:43, Laurent Vivier wrote: > This patch allows to use loop device with partitionned disk image. > > Original behavior of loop is not modified. > > A new parameter is introduced to define how many partition we want to be > able to manage per loop device. This parameter is "max_part". > > For instance, to manage 63 partitions / loop device, we will do: > # modprobe max_part=63 > # ls -l /dev/loop?* > brw-rw---- 1 root disk 7, 0 2008-03-05 14:55 /dev/loop0 > brw-rw---- 1 root disk 7, 64 2008-03-05 14:55 /dev/loop1 > brw-rw---- 1 root disk 7, 128 2008-03-05 14:55 /dev/loop2 > brw-rw---- 1 root disk 7, 192 2008-03-05 14:55 /dev/loop3 > brw-rw---- 1 root disk 7, 256 2008-03-05 14:55 /dev/loop4 > brw-rw---- 1 root disk 7, 320 2008-03-05 14:55 /dev/loop5 > brw-rw---- 1 root disk 7, 384 2008-03-05 14:55 /dev/loop6 > brw-rw---- 1 root disk 7, 448 2008-03-05 14:55 /dev/loop7 > > And to attach a raw partitionned disk image, the original losetup is used: > > # losetup -f etch.img > # ls -l /dev/loop?* > brw-rw---- 1 root disk 7, 0 2008-03-05 14:55 /dev/loop0 > brw-rw---- 1 root disk 7, 1 2008-03-05 14:57 /dev/loop0p1 > brw-rw---- 1 root disk 7, 2 2008-03-05 14:57 /dev/loop0p2 > brw-rw---- 1 root disk 7, 5 2008-03-05 14:57 /dev/loop0p5 > brw-rw---- 1 root disk 7, 64 2008-03-05 14:55 /dev/loop1 > brw-rw---- 1 root disk 7, 128 2008-03-05 14:55 /dev/loop2 > brw-rw---- 1 root disk 7, 192 2008-03-05 14:55 /dev/loop3 > brw-rw---- 1 root disk 7, 256 2008-03-05 14:55 /dev/loop4 > brw-rw---- 1 root disk 7, 320 2008-03-05 14:55 /dev/loop5 > brw-rw---- 1 root disk 7, 384 2008-03-05 14:55 /dev/loop6 > brw-rw---- 1 root disk 7, 448 2008-03-05 14:55 /dev/loop7 > # mount /dev/loop0p1 /mnt > # ls /mnt > bench cdrom home lib mnt root srv usr > bin dev initrd lost+found opt sbin sys var > boot etc initrd.img media proc selinux tmp vmlinuz > # umount /mnt > # losetup -d /dev/loop0 > > Of course, the same behavior can be done using kpartx on a loop device, > but modifying loop avoids to stack several layers of block device (loop + > device mapper), this is a very light modification (40% of modifications > are to manage the new parameter). Moreover all partition tables known > by the kernel are managed (kpartx implements only a subset).
Do you think we do something similar for drivers/block/brd.c too? I'd like to try to maintain parity between them where possible...
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