[PATCH 08/13] pktcdvd: use bio_clone_fast() instead of bio_clone()

NeilBrown
2017-06-18T04:40:28Z

pktcdvd doesn't change the bi_io_vec of the clone bio,
so it is more efficient to use bio_clone_fast(), and not clone
the bi_io_vec.
This requires providing a bio_set, and it is safest to
provide a dedicated bio_set rather than sharing
fs_bio_set, which filesytems use.
This new bio_set, pkt_bio_set, can also be use for the bio_split()
call as the two allocations (bio_clone_fast, and bio_split) are
independent, neither can block a bio allocated by the other.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: NeilBrown <neilb@suse.com>
---
drivers/block/pktcdvd.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 1f363638b453..26c04baae967 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -98,6 +98,7 @@ static int write_congestion_on = PKT_WRITE_CONGESTION_ON;
static int write_congestion_off = PKT_WRITE_CONGESTION_OFF;
static struct mutex ctl_mutex; /* Serialize open/close/setup/teardown */
static mempool_t *psd_pool;
+static struct bio_set *pkt_bio_set;

static struct class *class_pktcdvd = NULL; /* /sys/class/pktcdvd */
static struct dentry *pkt_debugfs_root = NULL; /* /sys/kernel/debug/pktcdvd */
@@ -2310,7 +2311,7 @@ static void pkt_end_io_read_cloned(struct bio *bio)

static void pkt_make_request_read(struct pktcdvd_device *pd, struct bio *bio)
{
- struct bio *cloned_bio = bio_clone(bio, GFP_NOIO);
+ struct bio *cloned_bio = bio_clone_fast(bio, GFP_NOIO, pkt_bio_set);
struct packet_stacked_data *psd = mempool_alloc(psd_pool, GFP_NOIO);

psd->pd = pd;
@@ -2455,7 +2456,7 @@ static blk_qc_t pkt_make_request(struct request_queue *q, struct bio *bio)

split = bio_split(bio, last_zone -
bio->bi_iter.bi_sector,
- GFP_NOIO, fs_bio_set);
+ GFP_NOIO, pkt_bio_set);
bio_chain(split, bio);
} else {
split = bio;
@@ -2924,6 +2925,11 @@ static int __init pkt_init(void)
sizeof(struct packet_stacked_data));
if (!psd_pool)
return -ENOMEM;
+ pkt_bio_set = bioset_create(BIO_POOL_SIZE, 0, 0);
+ if (!pkt_bio_set) {
+ mempool_destroy(psd_pool);
+ return -ENOMEM;
+ }

ret = register_blkdev(pktdev_major, DRIVER_NAME);
if (ret < 0) {
@@ -2956,6 +2962,7 @@ static int __init pkt_init(void)
unregister_blkdev(pktdev_major, DRIVER_NAME);
out2:
mempool_destroy(psd_pool);
+ bioset_free(pkt_bio_set);
return ret;
}

@@ -2969,6 +2976,7 @@ static void __exit pkt_exit(void)

unregister_blkdev(pktdev_major, DRIVER_NAME);
mempool_destroy(psd_pool);
+ bioset_free(pkt_bio_set);
}

MODULE_DESCRIPTION("Packet writing layer for CD/DVD drives");