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authorMing Lei <ming.lei@redhat.com>2019-02-15 19:13:23 +0800
committerJens Axboe <axboe@kernel.dk>2019-02-15 08:40:12 -0700
commit2705c93742e91730d335838025d75d8043861174 (patch)
tree16e379f17a745cbb3a1f8d7ba5ffe7e2b8ddee86 /drivers
parentac4fa1d107addb2c6b21067d8945a39316a09fc8 (diff)
block: kill QUEUE_FLAG_NO_SG_MERGE
Since bdced438acd83ad83a6c ("block: setup bi_phys_segments after splitting"), physical segment number is mainly figured out in blk_queue_split() for fast path, and the flag of BIO_SEG_VALID is set there too. Now only blk_recount_segments() and blk_recalc_rq_segments() use this flag. Basically blk_recount_segments() is bypassed in fast path given BIO_SEG_VALID is set in blk_queue_split(). For another user of blk_recalc_rq_segments(): - run in partial completion branch of blk_update_request, which is an unusual case - run in blk_cloned_rq_check_limits(), still not a big problem if the flag is killed since dm-rq is the only user. Multi-page bvec is enabled now, not doing S/G merging is rather pointless with the current setup of the I/O path, as it isn't going to save you a significant amount of cycles. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/md/dm-table.c13
1 files changed, 0 insertions, 13 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 4b1be754cc41..ba9481f1bf3c 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1698,14 +1698,6 @@ static int device_is_not_random(struct dm_target *ti, struct dm_dev *dev,
return q && !blk_queue_add_random(q);
}
-static int queue_supports_sg_merge(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_NO_SG_MERGE, &q->queue_flags);
-}
-
static bool dm_table_all_devices_attribute(struct dm_table *t,
iterate_devices_callout_fn func)
{
@@ -1902,11 +1894,6 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
if (!dm_table_supports_write_zeroes(t))
q->limits.max_write_zeroes_sectors = 0;
- if (dm_table_all_devices_attribute(t, queue_supports_sg_merge))
- blk_queue_flag_clear(QUEUE_FLAG_NO_SG_MERGE, q);
- else
- blk_queue_flag_set(QUEUE_FLAG_NO_SG_MERGE, q);
-
dm_table_verify_integrity(t);
/*