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drbd: new disk-option disable-write-same

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Some backend devices claim to support write-same,
but would fail actual write-same requests.

Allow to set (or toggle) whether or not DRBD tries to support write-same.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Lars Ellenberg 2017-08-29 10:20:38 +02:00 committed by Jens Axboe
parent c200d98687
commit 9de7e14a1a
3 changed files with 21 additions and 5 deletions
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15
drivers/block/drbd/drbd_nl.c
View File

@ -1236,12 +1236,18 @@ static void fixup_discard_if_not_supported(struct request_queue *q)
static void decide_on_write_same_support(struct drbd_device *device,
struct request_queue *q,
struct request_queue *b, struct o_qlim *o)
struct request_queue *b, struct o_qlim *o,
bool disable_write_same)
{
struct drbd_peer_device *peer_device = first_peer_device(device);
struct drbd_connection *connection = peer_device->connection;
bool can_do = b ? b->limits.max_write_same_sectors : true;
if (can_do && disable_write_same) {
can_do = false;
drbd_info(peer_device, "WRITE_SAME disabled by config\n");
}
if (can_do && connection->cstate >= C_CONNECTED && !(connection->agreed_features & DRBD_FF_WSAME)) {
can_do = false;
drbd_info(peer_device, "peer does not support WRITE_SAME\n");
@ -1302,6 +1308,7 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
struct request_queue *b = NULL;
struct disk_conf *dc;
bool discard_zeroes_if_aligned = true;
bool disable_write_same = false;
if (bdev) {
b = bdev->backing_bdev->bd_disk->queue;
@ -1311,6 +1318,7 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
dc = rcu_dereference(device->ldev->disk_conf);
max_segments = dc->max_bio_bvecs;
discard_zeroes_if_aligned = dc->discard_zeroes_if_aligned;
disable_write_same = dc->disable_write_same;
rcu_read_unlock();
blk_set_stacking_limits(&q->limits);
@ -1321,7 +1329,7 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
blk_queue_max_segments(q, max_segments ? max_segments : BLK_MAX_SEGMENTS);
blk_queue_segment_boundary(q, PAGE_SIZE-1);
decide_on_discard_support(device, q, b, discard_zeroes_if_aligned);
decide_on_write_same_support(device, q, b, o);
decide_on_write_same_support(device, q, b, o, disable_write_same);
if (b) {
blk_queue_stack_limits(q, b);
@ -1612,7 +1620,8 @@ int drbd_adm_disk_opts(struct sk_buff *skb, struct genl_info *info)
if (write_ordering_changed(old_disk_conf, new_disk_conf))
drbd_bump_write_ordering(device->resource, NULL, WO_BDEV_FLUSH);
if (old_disk_conf->discard_zeroes_if_aligned != new_disk_conf->discard_zeroes_if_aligned)
if (old_disk_conf->discard_zeroes_if_aligned != new_disk_conf->discard_zeroes_if_aligned
|| old_disk_conf->disable_write_same != new_disk_conf->disable_write_same)
drbd_reconsider_queue_parameters(device, device->ldev, NULL);
drbd_md_sync(device);

3
include/linux/drbd_genl.h
View File

@ -132,7 +132,8 @@ GENL_struct(DRBD_NLA_DISK_CONF, 3, disk_conf,
__flg_field_def(18, DRBD_GENLA_F_MANDATORY, disk_drain, DRBD_DISK_DRAIN_DEF)
__flg_field_def(19, DRBD_GENLA_F_MANDATORY, md_flushes, DRBD_MD_FLUSHES_DEF)
__flg_field_def(23, 0 /* OPTIONAL */, al_updates, DRBD_AL_UPDATES_DEF)
__flg_field_def(24, 0 /* OPTIONAL */, discard_zeroes_if_aligned, DRBD_DISCARD_ZEROES_IF_ALIGNED)
__flg_field_def(24, 0 /* OPTIONAL */, discard_zeroes_if_aligned, DRBD_DISCARD_ZEROES_IF_ALIGNED_DEF)
__flg_field_def(26, 0 /* OPTIONAL */, disable_write_same, DRBD_DISABLE_WRITE_SAME_DEF)
)
GENL_struct(DRBD_NLA_RESOURCE_OPTS, 4, res_opts,

8
include/linux/drbd_limits.h
View File

@ -209,12 +209,18 @@
#define DRBD_MD_FLUSHES_DEF 1
#define DRBD_TCP_CORK_DEF 1
#define DRBD_AL_UPDATES_DEF 1
/* We used to ignore the discard_zeroes_data setting.
* To not change established (and expected) behaviour,
* by default assume that, for discard_zeroes_data=0,
* we can make that an effective discard_zeroes_data=1,
* if we only explicitly zero-out unaligned partial chunks. */
#define DRBD_DISCARD_ZEROES_IF_ALIGNED 1
#define DRBD_DISCARD_ZEROES_IF_ALIGNED_DEF 1
/* Some backends pretend to support WRITE SAME,
* but fail such requests when they are actually submitted.
* This is to tell DRBD to not even try. */
#define DRBD_DISABLE_WRITE_SAME_DEF 0
#define DRBD_ALLOW_TWO_PRIMARIES_DEF 0
#define DRBD_ALWAYS_ASBP_DEF 0