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

On Fri, Mar 2, 2012 at 6:28 PM, Joseph Glanville
[off-list ref] 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 [off-list ref] wrote:

quoted

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
[off-list ref] wrote:

quoted

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 [off-list ref] wrote:

quoted

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
[off-list ref] wrote:

quoted

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 [off-list ref] wrote:

quoted

Oh - try stracing the pvcreate and see what happens.

On Thu, Mar 1, 2012 at 10:03 PM, Kent Overstreet
[off-list ref] wrote:

quoted

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
[off-list ref] wrote:

quoted

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.

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99 52 | Mobile: 0428 754 846

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Founder | Director | VP Research
Orion Virtualisation Solutions | www.orionvm.com.au | Phone: 1300 56
99 52 | Mobile: 0428 754 846