On Tue, Oct 30, 2007 at 04:53:17PM +0100, Karel Zak wrote:
> On Sat, Oct 27, 2007 at 12:44:51PM +0200, [EMAIL PROTECTED] wrote:
> > it seems that losetup doesn`t yet honour recent kernel change (see
> > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=73285082745045bcd64333c1fbaa88f8490f2626
> > ) to allow more than 256 loop-devices.
>
> Ah, I remember this thing from lkml.
>
> > loop-device creation is dynamically now, is there already work in
> > progress for support in losetup ?
>
> If I good remember there is not any other who how create a loop device
> than by "max_loop" or "mknod /dev/loopN". It means we needn't to add
> to losetup(8) any extra support for dynamically allocated loop devices.
>
> So, we need increment hardcoded limit of loop devices only. Right?
Note, there is also list of loop devices in /sys/block, but it's
useless for never used loop devices. See:
# mknod /dev/loop100 b 7 100
# ls -la /dev/loop100
brw-r--r-- 1 root root 7, 100 2007-10-30 17:14 /dev/loop100
# stat /sys/block/loop100
stat: cannot stat `/sys/block/loop100': No such file or directory
^^^^^^^^^^^^^^^^^^^
Why? It doesn't make sense. Ken, cannot we create /sys/block/loopN
when the device is allocated in kernel? It seems kernel creates
these /sys files when the device is used first time.
# losetup /dev/loop100 /mnt/store/images/fs/ext3.img
# stat -t /sys/block/loop100
/sys/block/loop100 0 0 41ed 0 0 0 13994 4 0 0 1193761350 1193760920
1193760920 4096
# losetup -d /dev/loop100
# stat -t /sys/block/loop100
/sys/block/loop100 0 0 41ed 0 0 0 13994 4 0 0 1193761350 1193760920
1193760920 4096
Wow, the directory /sys/block/loop100 is persistent now.
BTW, losetup -a (and -f) is useless when you have holes in list of
devices, for example I have:
/dev/loop0
/dev/loop1
/dev/loop2
/dev/loop3
/dev/loop4
/dev/loop5
/dev/loop6
/dev/loop7
/dev/loop100
# losetup /dev/loop100 /mnt/store/images/fs/ext3.img
# losetup /dev/loop100
/dev/loop100: [0807]:21921802 (/mnt/store/images/fs/ext3.img)
# losetup -a <--- nothing... loop100 is invisible. Bug :-(
Karel
--
Karel Zak <[EMAIL PROTECTED]>
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