[PATCH V2 0/1] blk-lib: cleanup bdev_get_queue()

Chaitanya Kulkarni
2022-02-15T11:53:02Z

Hi,

Based on the comment in the include/linux/blkdev.h:bdev_get_queue()
the return value of the function will never be NULL. This patch series
removes those checks present in the blk-lib.c, also removes the not
needed local variable pointer to request_queue from the write_zeroes
helpers.

Below is the test log for discard (__blkdev_issue_disacrd()) and
write-zeroes (__blkdev_issue_write_zeroes/__blkdev_issue_zero_pages()).

-ck

changes from V1:-

1. squash all patches into single patch. (Jens)

Chaitanya Kulkarni (1):
blk-lib: don't check bdev_get_queue() NULL check

block/blk-lib.c | 14 --------------
1 file changed, 14 deletions(-)

1. Execute discard (__blkdev_issue_disacrd()) and write-zeroes
(__blkdev_issue_write_zeroes, __blkdev_issue_zero_pages())

+ git diff block drivers/block/null_blk
diff --git a/block/blk-lib.c b/block/blk-lib.c
index fc6ea52e7482..84e5f31436d7 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -79,6 +79,8 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,

WARN_ON_ONCE((req_sects << 9) > UINT_MAX);

+ pr_info("%s %d sector %llu nr_sects %llu\n",
+ __func__, __LINE__, sector, nr_sects);
bio = blk_next_bio(bio, bdev, 0, op, gfp_mask);
bio->bi_iter.bi_sector = sector;
bio->bi_iter.bi_size = req_sects << 9;
@@ -237,6 +239,8 @@ static int __blkdev_issue_write_zeroes(struct block_device *bdev,
return -EOPNOTSUPP;

while (nr_sects) {
+ pr_info("%s %d sector %llu nr_sects %llu\n",
+ __func__, __LINE__, sector, nr_sects);
bio = blk_next_bio(bio, bdev, 0, REQ_OP_WRITE_ZEROES, gfp_mask);
bio->bi_iter.bi_sector = sector;
if (flags & BLKDEV_ZERO_NOUNMAP)
@@ -282,6 +286,8 @@ static int __blkdev_issue_zero_pages(struct block_device *bdev,
return -EPERM;

while (nr_sects != 0) {
+ pr_info("%s %d sector %llu nr_sects %llu\n",
+ __func__, __LINE__, sector, nr_sects);
bio = blk_next_bio(bio, bdev, __blkdev_sectors_to_bio_pages(nr_sects),
REQ_OP_WRITE, gfp_mask);
bio->bi_iter.bi_sector = sector;
diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 13004beb48ca..584ac0519c3e 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -84,6 +84,9 @@ static bool g_virt_boundary = false;
module_param_named(virt_boundary, g_virt_boundary, bool, 0444);
MODULE_PARM_DESC(virt_boundary, "Require a virtual boundary for the device. Default: False");

+static bool g_write_zeroes = false;
+module_param_named(write_zeroes, g_write_zeroes, bool, 0444);
+
static int g_no_sched;
module_param_named(no_sched, g_no_sched, int, 0444);
MODULE_PARM_DESC(no_sched, "No io scheduler");
@@ -1755,25 +1758,12 @@ static void null_del_dev(struct nullb *nullb)

static void null_config_discard(struct nullb *nullb)
{
- if (nullb->dev->discard == false)
- return;
-
- if (!nullb->dev->memory_backed) {
- nullb->dev->discard = false;
- pr_info("discard option is ignored without memory backing\n");
- return;
- }
-
- if (nullb->dev->zoned) {
- nullb->dev->discard = false;
- pr_info("discard option is ignored in zoned mode\n");
- return;
- }
-
nullb->q->limits.discard_granularity = nullb->dev->blocksize;
nullb->q->limits.discard_alignment = nullb->dev->blocksize;
blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
blk_queue_flag_set(QUEUE_FLAG_DISCARD, nullb->q);
+ if (g_write_zeroes)
+ blk_queue_max_write_zeroes_sectors(nullb->q, UINT_MAX >> 9);
}

static const struct block_device_operations null_bio_ops = {
+ modprobe -r null_blk
+ modprobe null_blk
+ blkdiscard -o 0 -l 40960 /dev/nullb0
+ dmesg -c
[ 261.219011] null_blk: module loaded
*[ 261.232872] __blkdev_issue_discard 82 sector 0 nr_sects 80*
+ blkdiscard -z -o 0 -l 40960 /dev/nullb0
+ dmesg -c
*[ 261.245818] __blkdev_issue_zero_pages 289 sector 0 nr_sects 80*
+ modprobe -r null_blk
+ modprobe null_blk write_zeroes=1
+ blkdiscard -z -o 0 -l 40960 /dev/nullb0
+ dmesg -c
[ 261.328251] null_blk: module loaded
*[ 261.337313] __blkdev_issue_write_zeroes 242 sector 0 nr_sects 80*
+ modprobe -r null_blk
+ set +x

--
2.29.0