On 6/19/12 8:52 AM, Spelic wrote: > On 06/19/12 15:30, Mike Snitzer wrote: >> I don't recall Spelic saying anything about EOPNOTSUPP. So what has made you zero in on an -EOPNOTSUPP return (which should not be happening)? > > Exactly: I do not know if EOPNOTSUPP is being returned or not. > > If this helps, I have configured dm-thin via lvm2 > LVM version: 2.02.95(2) (2012-03-06) > Library version: 1.02.74 (2012-03-06) > Driver version: 4.22.0 > > from dmsetup table I only see one option : "skip_block_zeroing", if and only if I configure it with -Zn . I do not see anything regarding ignore_discard > > vg1-pooltry1-tpool: 0 20971520 thin-pool 252:1 252:2 2048 0 1 skip_block_zeroing > vg1-pooltry1_tdata: 0 20971520 linear 9:20 62922752 > vg1-pooltry1_tmeta: 0 8192 linear 9:20 83894272 > vg1-thinlv1: 0 31457280 thin 252:3 1 > > > and in dmesg: > [ 33.685200] device-mapper: thin: Discard unsupported by data device (dm-2): Disabling discard passdown. > [ 33.709586] device-mapper: thin: Discard unsupported by data device (dm-6): Disabling discard passdown. > > > I do not know what is the mechanism for which xfs cannot unmap blocks from dm-thin, but it really can't. > If anyone has dm-thin installed he can try. This is 100% reproducible for me. Might be worth seeing if xfs is ever getting to its discard code? There is a tracepoint... # mount -t debugfs none /sys/kernel/debug # echo 1 > /sys/kernel/debug/tracing/tracing_enabled # echo 1 > /sys/kernel/debug/tracing/events/xfs/xfs_discard_extent/enable <run test> # cat /sys/kernel/debug/tracing/trace -Eric -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
