Re: [dm-devel] [PATCH RFC 7/7] dm: add support for IO polling
From: JeffleXu <jefflexu@linux.alibaba.com>
Date: 2021-01-08 03:13:24
Also in:
dm-devel, linux-block
On 12/23/20 7:26 PM, Jeffle Xu wrote:
quoted hunk ↗ jump to hunk
Enable iopoll when all underlying target devices supports iopoll. Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com> --- drivers/md/dm-table.c | 28 ++++++++++++++++++++++++++++ drivers/md/dm.c | 1 + 2 files changed, 29 insertions(+)diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 188f41287f18..b0cd5bf58c3c 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c@@ -1791,6 +1791,31 @@ static bool dm_table_requires_stable_pages(struct dm_table *t) return false; } +static int device_supports_poll(struct dm_target *ti, struct dm_dev *dev, + sector_t start, sector_t len, void *data) +{ + struct request_queue *q = bdev_get_queue(dev->bdev); + + return q && test_bit(QUEUE_FLAG_POLL, &q->queue_flags); +} + +static bool dm_table_supports_poll(struct dm_table *t) +{ + struct dm_target *ti; + unsigned int i; + + /* Ensure that all targets support iopoll. */ + for (i = 0; i < dm_table_get_num_targets(t); i++) { + ti = dm_table_get_target(t, i); + + if (!ti->type->iterate_devices || + !ti->type->iterate_devices(ti, device_supports_poll, NULL)) + return false; + } + + return true; +} + void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, struct queue_limits *limits) {@@ -1883,6 +1908,9 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q, #endif blk_queue_update_readahead(q); + + if (dm_table_supports_poll(t)) + blk_queue_flag_set(QUEUE_FLAG_POLL, q); }
This works in arbitrary bio-based DM stacking. Suppose the following
device stack:
dm0
dm1
nvme0 nvme1
dm 0 will check if dm1 has QUEUE_FLAG_POLL flag set.
quoted hunk ↗ jump to hunk
unsigned int dm_table_get_num_targets(struct dm_table *t)diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 03c2b867acaa..ffd2c5ead256 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c@@ -3049,6 +3049,7 @@ static const struct pr_ops dm_pr_ops = { }; static const struct block_device_operations dm_blk_dops = { + .iopoll = blk_bio_poll, .submit_bio = dm_submit_bio, .open = dm_blk_open, .release = dm_blk_close,
-- Thanks, Jeffle