I'm trying to do a very simple test were a single block device should
be ignored by LVM as a result of setting the filter directive in
lvm.conf. However, it isn't. That block device happens to be a DM
target (mapped to the zero target):
# dmsetup create foo7 --table "0 $((1*1024*1024*1024/512)) zero"
The filter in lvm.conf is not honored, here's how it's set:
devices {
...
filter = [ "r|/dev/mapper/foo7|" ]
...
}
I did run vgscan after editing lvm.conf. The relevant output of strace:
# strace -o strace lvs -vvvv -d > lvs 2>&1
...
stat("/dev/mapper/foo7", {st_mode=S_IFBLK|0660, st_rdev=makedev(253,
4), ...}) = 0
open("/dev/mapper/foo7", O_RDONLY|O_DIRECT|O_NOATIME) = 5
fstat(5, {st_mode=S_IFBLK|0660, st_rdev=makedev(253, 4), ...}) = 0
write(2, "#device/dev-io.c:533 ", 29) = 29
write(2, "Opened /dev/mapper/foo7 RO O_DIR"..., 35) = 35
write(2, "\n", 1) = 1
ioctl(5, BLKGETSIZE64, 1073741824) = 0
write(2, "#device/dev-io.c:310 ", 27) = 27
write(2, "/dev/mapper/foo7: size is 209715"..., 41) = 41
write(2, "\n", 1) = 1
close(5) = 0
write(2, "#device/dev-io.c:587 ", 29) = 29
write(2, "Closed /dev/mapper/foo7", 23) = 23
write(2, "\n", 1) = 1
write(2, "#ioctl/libdm-iface.c:1795 "..., 34) = 34
write(2, "dm status (253:4) OF [16384]"..., 37) = 37
write(2, "\n", 1) = 1
ioctl(4, DM_TABLE_STATUS, 0x7fa013383190) = 0
stat("/dev/mapper/foo7", {st_mode=S_IFBLK|0660, st_rdev=makedev(253,
4), ...}) = 0
open("/dev/mapper/foo7", O_RDONLY|O_DIRECT|O_NOATIME) = 5
fstat(5, {st_mode=S_IFBLK|0660, st_rdev=makedev(253, 4), ...}) = 0
write(2, "#device/dev-io.c:533 ", 29) = 29
write(2, "Opened /dev/mapper/foo7 RO O_DIR"..., 35) = 35
write(2, "\n", 1) = 1
ioctl(5, BLKBSZGET, 4096) = 0
write(2, "#device/dev-io.c:144 ", 29) = 29
write(2, "/dev/mapper/foo7: block size is "..., 42) = 42
write(2, "\n", 1) = 1
ioctl(5, BLKPBSZGET, 512) = 0
write(2, "#device/dev-io.c:155 ", 29) = 29
write(2, "/dev/mapper/foo7: physical block"..., 50) = 50
write(2, "\n", 1) = 1
lseek(5, 0, SEEK_SET) = 0
read(5,
It's stuck forever in read(2). And the output of lvs -vvvv -d:
# grep -E "foo7|dm-4" lvs
#device/dev-cache.c:338 /dev/dm-4: Added to device cache
#device/dev-cache.c:335 /dev/mapper/foo7: Aliased to /dev/dm-4
in device cache (preferred name)
#device/dev-cache.c:335 /dev/disk/by-id/dm-name-foo7: Aliased
to /dev/mapper/foo7 in device cache
#device/dev-cache.c:335 /dev/block/253:4: Aliased to
/dev/mapper/foo7 in device cache
#device/dev-io.c:533 Opened /dev/mapper/foo7 RO O_DIRECT
#device/dev-io.c:310 /dev/mapper/foo7: size is 2097152 sectors
#device/dev-io.c:587 Closed /dev/mapper/foo7
#device/dev-io.c:533 Opened /dev/mapper/foo7 RO O_DIRECT
#device/dev-io.c:144 /dev/mapper/foo7: block size is 4096 bytes
#device/dev-io.c:155 /dev/mapper/foo7: physical block size is 512 bytes
The LVM version is:
# lvm version
LVM version: 2.02.118(2)-RHEL6 (2015-09-08)
Library version: 1.02.95-RHEL6 (2015-09-08)
Driver version: 4.33.1
Is this how it's supposed to work? Am I missing something?
--
Thanos Makatos
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