I just opened a tracker ticket for this [1] -- let me know if you have any other QEMU improvement ideas. [1] http://tracker.ceph.com/issues/20070 On Wed, May 24, 2017 at 7:38 AM, Alexandre DERUMIER <aderumier@xxxxxxxxx> wrote: > Hi, > > is it planned to implement write zeroes in qemu rbd block driver soon ? > (bdrv_co_write_zeroes) > > It's really missing currently, as qemu drive-mirror need it to have sparse images on copy. > > Ref from my discussion with Paolo from redhat in 2014 about this: > https://lists.gnu.org/archive/html/qemu-devel/2014-10/msg01274.html > > > REgards, > > Alexandre > > ----- Mail original ----- > De: "Jason Dillaman" <jdillama@xxxxxxxxxx> > À: "Ilya Dryomov" <idryomov@xxxxxxxxx> > Cc: "ceph-devel" <ceph-devel@xxxxxxxxxxxxxxx>, "Christoph Hellwig" <hch@xxxxxx>, "Hannes Reinecke" <hare@xxxxxxxx> > Envoyé: Mardi 23 Mai 2017 20:28:00 > Objet: Re: [PATCH] rbd: implement REQ_OP_WRITE_ZEROES > > lgtm > > Reviewed-by: Jason Dillaman <dillaman@xxxxxxxxxx> > > On Tue, May 23, 2017 at 11:08 AM, Ilya Dryomov <idryomov@xxxxxxxxx> wrote: >> Commit 93c1defedcae ("rbd: remove the discard_zeroes_data flag") >> explicitly didn't implement REQ_OP_WRITE_ZEROES for rbd, while the >> following commit 48920ff2a5a9 ("block: remove the discard_zeroes_data >> flag") dropped ->discard_zeroes_data in favor of REQ_OP_WRITE_ZEROES. >> >> rbd does support efficient zeroing via CEPH_OSD_OP_ZERO opcode and will >> release either some or all blocks depending on whether the zeroing >> request is rbd_obj_bytes() aligned. This is how we currently implement >> discards, so REQ_OP_WRITE_ZEROES can be identical to REQ_OP_DISCARD for >> now. Caveats: >> >> - REQ_NOUNMAP is ignored, but AFAICT that's true of at least two other >> current implementations - nvme and loop >> >> - there is no ->write_zeroes_alignment and blk_bio_write_zeroes_split() >> is hence less helpful than blk_bio_discard_split(), but this can (and >> should) be fixed on the rbd side >> >> In the future we will split these into two code paths to respect >> REQ_NOUNMAP on zeroout and save on zeroing blocks that couldn't be >> released on discard. >> >> Fixes: 93c1defedcae ("rbd: remove the discard_zeroes_data flag") >> Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx> >> --- >> drivers/block/rbd.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c >> index 454bf9c34882..c16f74547804 100644 >> --- a/drivers/block/rbd.c >> +++ b/drivers/block/rbd.c >> @@ -4023,6 +4023,7 @@ static void rbd_queue_workfn(struct work_struct *work) >> >> switch (req_op(rq)) { >> case REQ_OP_DISCARD: >> + case REQ_OP_WRITE_ZEROES: >> op_type = OBJ_OP_DISCARD; >> break; >> case REQ_OP_WRITE: >> @@ -4420,6 +4421,7 @@ static int rbd_init_disk(struct rbd_device *rbd_dev) >> q->limits.discard_granularity = segment_size; >> q->limits.discard_alignment = segment_size; >> blk_queue_max_discard_sectors(q, segment_size / SECTOR_SIZE); >> + blk_queue_max_write_zeroes_sectors(q, segment_size / SECTOR_SIZE); >> >> if (!ceph_test_opt(rbd_dev->rbd_client->client, NOCRC)) >> q->backing_dev_info->capabilities |= BDI_CAP_STABLE_WRITES; >> -- >> 2.4.3 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > -- > Jason > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Jason -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
