hello ! if these is the most recent versions of dm-loop patch (don`t actually know for sure, see my last mail): http://kernel.org/pub/linux/kernel/people/agk/patches/2.6/editing/dm-loop.patch http://kernel.org/pub/linux/kernel/people/agk/patches/2.6/editing/dm-add-loop.patch then i may have found some bug, i`d like to report. i was doing some testing of dm-loop with latest dmsetup on a 2.6.20-rc5 system. i did some basic test, which seems to work ok. i can now map a file to become /dev/mapper/loop0 dmlosetup loop0 test.img -> device-mapper: loop: Finalized extent map of 1232 bytes, 44 entries. root@localhost ~ # ls -la /dev/mapper/loop0 brw------- 1 root root 252, 0 21. Jan 17:25 /dev/mapper/loop0 works ! hooray - great work ! while fiddling around a little bit, i accidentally tried to map that file a second time - anyway, i would expect this is quite ok and should work. dmlosetup loop1 test.img this bails out with the following error, leaving trace in dmesg: device-mapper: loop: file is already in use: /root/device-mapper/dmsetup/test.dat BUG: unable to handle kernel NULL pointer dereference at virtual address 00000000 printing eip: d097589c *pde = 00000000 Oops: 0000 [#1] PREEMPT SMP Modules linked in: dm_loop ipv6 snd_ens1371 gameport snd_rawmidi snd_ac97_codec ac97_bus pcnet32 i2c_piix4 i2c_core agpgart CPU: 0 EIP: 0060:[<d097589c>] Not tainted VLI EFLAGS: 00010292 (2.6.20-rc5 #1) EIP is at loop_setup_size+0x1c/0x1f0 [dm_loop] eax: 00000000 ebx: cb3289c0 ecx: d097105c edx: d0971020 esi: ffffffea edi: 00000001 ebp: d0971020 esp: cad47e58 ds: 007b es: 007b ss: 0068 Process dmlosetup (pid: 1787, ti=cad46000 task=cfe13aa0 task.ti=cad46000) Stack: c018ab46 00000008 cd08fbc0 c017a806 00000000 00000000 cfec9ee8 cfec9ec0 c018fcd3 cd4bc180 cacbe118 d097105c d0971020 cb3289c0 cb3289c0 ffffffea 00000001 d0971020 d0975bd3 d0978181 d09761b5 cb3289f8 cb3280c0 d0971020 Call Trace: [<c018ab46>] dput+0x86/0x140 [<c017a806>] __fput+0xf6/0x170 [<c018fcd3>] mntput_no_expire+0x13/0x70 [<d0975bd3>] loop_ctr+0xd3/0x170 [dm_loop] [<c049016b>] dm_table_add_target+0x12b/0x1e0 [<c04928c0>] populate_table+0x80/0xe0 [<c049297e>] table_load+0x5e/0x110 [<c0492920>] table_load+0x0/0x110 [<c04930db>] ctl_ioctl+0xcb/0x130 [<c0534ebc>] __up+0x1c/0x20 [<c018595a>] do_ioctl+0x6a/0xa0 [<c0185b1e>] vfs_ioctl+0x5e/0x1d0 [<c0185ccd>] sys_ioctl+0x3d/0x70 [<c0103252>] sysenter_past_esp+0x5f/0x85 ======================= Code: d0 e8 f9 19 7b ef eb b3 8d b4 26 00 00 00 00 55 57 56 53 83 ec 38 89 44 24 34 89 54 24 30 89 4c 24 2c 8b 40 04 8b 80 8c 00 00 00 <8b> 18 8b 4b 44 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 90 89 EIP: [<d097589c>] loop_setup_size+0x1c/0x1f0 [dm_loop] SS:ESP 0068:cad47e58 after this, if i do dmlosetup -d loop1 dmlosetup -d loop0 i cannot "rmmod dm-loop" , now telling me "device is in use", but it isn`t ! so, this looks like a bug to me, leaving dm-loop in an inconsitent state. furthermore, one question about naming conventions : dmlosetup testloop1 test.dat dmlosetup: Could not parse loop_device testloop1 Usage: losetup [-d|-a] [-e encryption] [-o offset] [-f|loop_device] [file] Couldn't process command line. so, it`s mandatory that loop_device needs to begin with "loop...." !? regards roland > -----Ursprüngliche Nachricht----- > Von: devzero@xxxxxx > Gesendet: 20.01.07 15:57:23 > An: breeves@xxxxxxxxxx > CC: dm-devel@xxxxxxxxxx > Betreff: Re: Re: device mapper integrated loops - and one more year ! > Hello Bryn, > > > >I'll see if we can get a revised version of the current patch for wider > >testing in the next couple of weeks - let me know if you would be > >interested in trying this out. > > not sure if i sent a reply to this or have missed this - but, yes - i`m still interested very much in using dm-loop ! > > is there anything new with this? > do i have to expect issues with files >2gb ? (i need to loopback mount dvd iso-images) > > is there a download url for the latest dm-loop patch so i can do some tests and report feedback ? > > i couldn`t find it at http://sources.redhat.com/cgi-bin/cvsweb.cgi/device-mapper/?cvsroot=dm and i`m not sure if i should take that one from http://kernel.org/pub/linux/kernel/people/agk/patches/2.6/ > > TIA > roland > > > > > Hello ! > > > > after desparately seeking for a solution to have more than 256 loop > > devices (for a huge cd-rom server), i have recently come across > > dm-loop, which looks very promising (to replace loop.c) > > > > can i have more than 256 devices which this? > > Hi Roland, > > Yes, dm-loop will support as many loop devices as device-mapper can allow. > > > our cd-rom server is going to have more than 256 iso-images soon and > > i need to upgrade to a more recent OS, anyway, so this won`t be a > > problem that dm-loop is so brand new. > > > > but - any timeline for dm-loop mainline inclusion ? > > > > should i wait for 2.6.19 or 2.6.20 ? > > There isn't a fixed timeline. We are currently working to improve the > lookup code - the prototype patch uses a linear search which doesn't > scale well for large/fragmented image files. I have some tests running > at the moment and we hope to have something soon - the results so far > are good, it's just a case of selecting between a couple of different > methods. > > The changes dm-loop requires in device-mapper core are pretty minor and > have already been merged in 2.6.19, so it's just the dm-loop patch > itself remaining. > > > is it already useable with less recent kernels, i.e. can i download > > dm-loop patch and recent dmsetup tool and use with older kernel ? > > This should work fine - there are a couple of known issues with the > existing patch, but unless you are using large images (>2G), or have a > severely fragmented filesystem you shouldn't run into these. > > I'll see if we can get a revised version of the current patch for wider > testing in the next couple of weeks - let me know if you would be > interested in trying this out. > > Thanks, > > Bryn. _____________________________________________________________________ Der WEB.DE SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen! http://smartsurfer.web.de/?mc=100071&distributionid=000000000066 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
