[linux-lvm] bcache and dm targets (specifically lvm)

Sat Mar 3 02:44:07 UTC 2012

Oh, good! I thought it'd require a patch, that's much better.

On Fri, Mar 2, 2012 at 6:28 PM, Joseph Glanville
<joseph.glanville at orionvm.com.au> wrote:
> Ahh!
>
> I didn't know LVM had a device type lookup table. You can see if you
> look further that it also reads new types from the lvm.conf file.
> Adding this line to lvm.conf fixes the problem:
>
> types = [ "bcache", 16 ]
>
> I would imagine if merged it would be added to the internal compiled in table.
>
> Thanks for the pointer.
> Joseph.
>
> On 3 March 2012 13:17, Kent Overstreet <koverstreet at google.com> wrote:
>> I found the bug. Ugh...
>>
>> pvcreate refuses to use a device it doesn't recognize - look at the
>> lvm2 source, lib/filters/filter.c
>>
>> I don't know why and I don't think I want to know. I imagine it'd work
>> if you commented out the offending check (line 143 in my version).
>>
>> Maybe one of them can explain what's going on.
>>
>> On Fri, Mar 2, 2012 at 4:48 PM, Joseph Glanville
>> <joseph.glanville at orionvm.com.au> wrote:
>>> Cheers, I will try with a full disk device sometime later today.
>>>
>>> Thanks for you help,
>>> Joseph.
>>>
>>> On 3 March 2012 11:01, Kent Overstreet <koverstreet at google.com> wrote:
>>>> Strange, I don't see anything obvious in that log. Well, shouldn't be
>>>> too hard to track down, I'll see if I can reproduce it.
>>>>
>>>> On Fri, Mar 2, 2012 at 2:37 PM, Joseph Glanville
>>>> <joseph.glanville at orionvm.com.au> wrote:
>>>>> Hi Kent,
>>>>>
>>>>> The block device did indeed get created in /dev and the correct
>>>>> pointer exists in /sys/block/bcache0/dev
>>>>> I straced pvcreate and attached the outout, I couldn't see anything
>>>>> that far out of the ordinary though - bar the return that the device
>>>>> had been filtered.
>>>>> I am using commit f4c09286dd3f761310b24bc03e5ce95793a9a30c of
>>>>> bcache-tools.git and commit 7c3e597ca0f5c87767548d1e9aced024aa558b2a
>>>>> of linux-bcache.git
>>>>>
>>>>> The other thing I noticed was that the /dev/disk-by/uuid symlink
>>>>> wasn't created. I went ahead and created this myself but I will
>>>>> investigate why the udev rule didn't do this for me.
>>>>>
>>>>> Below is relevant lines from pvscan and pvcreate:
>>>>>
>>>>> dev05 ~ # cat pvscan.log | grep bcache
>>>>> execve("/sbin/pvscan", ["pvscan", "/dev/bcache0"], [/* 23 vars */]) = 0
>>>>> read(3, "strace\0pvscan\0/dev/bcache0\0", 31) = 27
>>>>> readlink("/sys/class/block/bcache0",
>>>>> "../../devices/virtual/block/bcache0"..., 1024) = 35
>>>>> stat("/sys/devices/virtual/block/bcache0/uevent",
>>>>> {st_mode=S_IFREG|0644, st_size=4096, ...}) = 0
>>>>> readlink("/sys/devices/virtual/block/bcache0", 0x7fff9e17aea0, 1024) =
>>>>> -1 EINVAL (Invalid argument)
>>>>> stat("/sys/devices/virtual/block/bcache0/uevent",
>>>>> {st_mode=S_IFREG|0644, st_size=4096, ...}) = 0
>>>>> open("/sys/devices/virtual/block/bcache0/uevent", O_RDONLY|O_CLOEXEC) = 4
>>>>> read(4, "MAJOR=252\nMINOR=0\nDEVNAME=bcache"..., 4096) = 47
>>>>> readlink("/sys/devices/virtual/block/bcache0/subsystem",
>>>>> "../../../../class/block"..., 1024) = 23
>>>>> read(4, "N:bcache0\nW:40\nI:580433490\n", 4096) = 27
>>>>> stat("/dev/bcache0", {st_mode=S_IFBLK|0660, st_rdev=makedev(252, 0), ...}) = 0
>>>>> stat("/sys/class/block/bcache0/dev", {st_mode=S_IFREG|0444,
>>>>> st_size=4096, ...}) = 0
>>>>> open("/sys/class/block/bcache0/dev", O_RDONLY) = 6
>>>>>
>>>>> dev05 ~ # cat pvcreate-strace.log | grep bcache
>>>>> execve("/sbin/pvcreate", ["pvcreate", "/dev/bcache0"], [/* 23 vars */]) = 0
>>>>> read(3, "strace\0pvcreate\0/dev/bcache0\0", 31) = 29
>>>>> stat("/dev/bcache0", {st_mode=S_IFBLK|0660, st_rdev=makedev(252, 0), ...}) = 0
>>>>> readlink("/sys/dev/block/252:0",
>>>>> "../../devices/virtual/block/bcache0", 1024) = 35
>>>>> stat("/sys/devices/virtual/block/bcache0/uevent",
>>>>> {st_mode=S_IFREG|0644, st_size=4096, ...}) = 0
>>>>> stat("/sys/class/block/bcache0/dev", {st_mode=S_IFREG|0444,
>>>>> st_size=4096, ...}) = 0
>>>>> open("/sys/class/block/bcache0/dev", O_RDONLY) = 6
>>>>> stat("/dev/bcache0", {st_mode=S_IFBLK|0660, st_rdev=makedev(252, 0), ...}) = 0
>>>>> stat("/dev/bcache0", {st_mode=S_IFBLK|0660, st_rdev=makedev(252, 0), ...}) = 0
>>>>> stat("/sys/class/block/bcache0/dev", {st_mode=S_IFREG|0444,
>>>>> st_size=4096, ...}) = 0
>>>>> open("/sys/class/block/bcache0/dev", O_RDONLY) = 6
>>>>> write(2, "Device /dev/bcache0 not found (o"..., 56Device /dev/bcache0
>>>>> not found (or ignored by filtering).) = 56
>>>>>
>>>>> Kind regards,
>>>>> Joseph.
>>>>>
>>>>>
>>>>> On 2 March 2012 17:44, Kent Overstreet <kent.overstreet at gmail.com> wrote:
>>>>>> Oh - try stracing the pvcreate and see what happens.
>>>>>>
>>>>>> On Thu, Mar 1, 2012 at 10:03 PM, Kent Overstreet
>>>>>> <kent.overstreet at gmail.com> wrote:
>>>>>>> Weird.
>>>>>>>
>>>>>>> Did the /dev/bcache0 device get create created by udev?
>>>>>>>
>>>>>>> It's possible my code isn't poking the right thing. *mutters about the
>>>>>>> block layer...*
>>>>>>>
>>>>>>> On Thu, Mar 1, 2012 at 9:49 PM, Joseph Glanville
>>>>>>> <joseph.glanville at orionvm.com.au> wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> I can't use bcache devices as members of lvm volume groups because
>>>>>>>> dmsetup can't find the devices.
>>>>>>>> It provides the ever useful feedback of:
>>>>>>>> # pvcreate /dev/bcache0
>>>>>>>>   Device /dev/bcache0 not found (or ignored by filtering).
>>>>>>>>
>>>>>>>> My LVM.conf is only filtering out nbd devices:
>>>>>>>> filter = [ "r|/dev/nbd.*|", "a/.*/" ]
>>>>>>>>
>>>>>>>> Any insight would be greatly appreciated. :)
>>>>>>>>
>>>>>>>> I also noted that bcache devices don't appear in iostat..
>>>>>>>>
>>>>>>>> Joseph.
>>>>>>>>
>>>>>>>> --
>>>>>>>> Founder | Director | VP Research
>>>>>>>> Orion Virtualisation Solutions | www.orionvm.com.au | Phone: 1300 56
>>>>>>>> 99 52 | Mobile: 0428 754 846
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Founder | Director | VP Research
>>>>>>>> Orion Virtualisation Solutions | www.orionvm.com.au | Phone: 1300 56
>>>>>>>> 99 52 | Mobile: 0428 754 846
>>>>>>>> --
>>>>>>>> To unsubscribe from this list: send the line "unsubscribe linux-bcache" in
>>>>>>>> the body of a message to majordomo at vger.kernel.org
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>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Founder | Director | VP Research
>>>>> Orion Virtualisation Solutions | www.orionvm.com.au | Phone: 1300 56
>>>>> 99 52 | Mobile: 0428 754 846
>>>>> --
>>>>> To unsubscribe from this list: send the line "unsubscribe linux-bcache" in
>>>>> the body of a message to majordomo at vger.kernel.org
>>>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>
>>>
>>>
>>> --
>>> Founder | Director | VP Research
>>> Orion Virtualisation Solutions | www.orionvm.com.au | Phone: 1300 56
>>> 99 52 | Mobile: 0428 754 846
>
>
>
> --
> Founder | Director | VP Research
> Orion Virtualisation Solutions | www.orionvm.com.au | Phone: 1300 56
> 99 52 | Mobile: 0428 754 846