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| author |   Ming Lei <ming.lei@redhat.com> | 2019-02-15 19:13:23 +0800 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2019-02-15 08:40:12 -0700 |
| commit | 2705c93742e91730d335838025d75d8043861174 (patch) | |
| tree | 16e379f17a745cbb3a1f8d7ba5ffe7e2b8ddee86 /drivers/md | |
| parent | block: document usage of bio iterator helpers (diff) | |
| download | linux-dev-2705c93742e91730d335838025d75d8043861174.tar.xz linux-dev-2705c93742e91730d335838025d75d8043861174.zip | |
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/md')
| -rw-r--r-- | drivers/md/dm-table.c | 13 |
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); /* |