by Chaitanya Kulkarni

[permalink] [raw]

Subject: Re: [PATCH v9 9/9] null_blk: add support for copy offload

On 4/11/23 01:10, Anuj Gupta wrote:
> From: Nitesh Shetty <[email protected]>
>
> Implementaion is based on existing read and write infrastructure.
> copy_max_bytes: A new configfs and module parameter is introduced, which
> can be used to set hardware/driver supported maximum copy limit.
>
> Suggested-by: Damien Le Moal <[email protected]>
> Signed-off-by: Anuj Gupta <[email protected]>
> Signed-off-by: Nitesh Shetty <[email protected]>
> Signed-off-by: Vincent Fu <[email protected]>
> ---
> drivers/block/null_blk/main.c | 101 ++++++++++++++++++++++++++++++
> drivers/block/null_blk/null_blk.h | 8 +++
> 2 files changed, 109 insertions(+)
>
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index bc2c58724df3..e273e18ace74 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -157,6 +157,10 @@ static int g_max_sectors;
> module_param_named(max_sectors, g_max_sectors, int, 0444);
> MODULE_PARM_DESC(max_sectors, "Maximum size of a command (in 512B sectors)");
>
> +static int g_copy_max_bytes = COPY_MAX_BYTES;

how about following ? matches nullb_device->copy_max_bytes type ..

-static int g_copy_max_bytes = COPY_MAX_BYTES;
-module_param_named(copy_max_bytes, g_copy_max_bytes, int, 0444);
+static unsigned long g_copy_max_bytes = COPY_MAX_BYTES;
+module_param_named(copy_max_bytes, g_copy_max_bytes, ulong, 0444);

[...]

> @@ -631,6 +637,7 @@ static ssize_t memb_group_features_show(struct config_item *item, char *page)
> "badblocks,blocking,blocksize,cache_size,"
> "completion_nsec,discard,home_node,hw_queue_depth,"
> "irqmode,max_sectors,mbps,memory_backed,no_sched,"
> + "copy_max_bytes,"
> "poll_queues,power,queue_mode,shared_tag_bitmap,size,"
> "submit_queues,use_per_node_hctx,virt_boundary,zoned,"
> "zone_capacity,zone_max_active,zone_max_open,"

why not ?

@@ -637,11 +637,12 @@ static ssize_t memb_group_features_show(struct config_item *item, char *page)
"badblocks,blocking,blocksize,cache_size,"
"completion_nsec,discard,home_node,hw_queue_depth,"
"irqmode,max_sectors,mbps,memory_backed,no_sched,"
- "copy_max_bytes,"
"poll_queues,power,queue_mode,shared_tag_bitmap,size,"
"submit_queues,use_per_node_hctx,virt_boundary,zoned,"
"zone_capacity,zone_max_active,zone_max_open,"
- "zone_nr_conv,zone_offline,zone_readonly,zone_size\n");
+ "zone_nr_conv,zone_offline,zone_readonly,zone_size"
+ "copy_max_bytes\n");
}

[...]

+static inline int nullb_setup_copy_read(struct nullb *nullb,
+ struct bio *bio)
+{
+ struct nullb_copy_token *token = bvec_kmap_local(&bio->bi_io_vec[0]);
+
+ memcpy(token->subsys, "nullb", 5);

do you really need to use memcpy here ? can token->subsys be a pointer
and use with assignment token->subsys = nullb ?

+ token->sector_in = bio->bi_iter.bi_sector;
+ token->nullb = nullb;
+ token->sectors = bio->bi_iter.bi_size >> SECTOR_SHIFT;
+
+ return 0;
+}
+

no point in return 0 , use local bool for fua instead of repeating
expression and no need to fold line for nullb_setup_copy_read()
makes is easy to read and removes extra lines and indentation see below :-

-static inline int nullb_setup_copy_read(struct nullb *nullb,
- struct bio *bio)
+static inline void nullb_setup_copy_read(struct nullb *nullb, struct bio *bio)
{
struct nullb_copy_token *token = bvec_kmap_local(&bio->bi_io_vec[0]);

- memcpy(token->subsys, "nullb", 5);
+ token->subsys = "nullb;
token->sector_in = bio->bi_iter.bi_sector;
token->nullb = nullb;
token->sectors = bio->bi_iter.bi_size >> SECTOR_SHIFT;
-
- return 0;
}

static inline int nullb_setup_copy_write(struct nullb *nullb,
@@ -1334,20 +1331,21 @@ static int null_handle_rq(struct nullb_cmd *cmd)
sector_t sector = blk_rq_pos(rq);
struct req_iterator iter;
struct bio_vec bvec;
+ bool fua = rq->cmd_flags & REQ_FUA;

if (rq->cmd_flags & REQ_COPY) {
if (op_is_write(req_op(rq)))
- return nullb_setup_copy_write(nullb, rq->bio,
- rq->cmd_flags & REQ_FUA);
- return nullb_setup_copy_read(nullb, rq->bio);
+ return nullb_setup_copy_write(nullb, rq->bio, fua);
+
+ nullb_setup_copy_read(nullb, rq->bio);
+ return 0;
}

spin_lock_irq(&nullb->lock);
rq_for_each_segment(bvec, rq, iter) {
len = bvec.bv_len;
err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
- op_is_write(req_op(rq)), sector,
- rq->cmd_flags & REQ_FUA);
+ op_is_write(req_op(rq)), sector, fua);
if (err) {
spin_unlock_irq(&nullb->lock);
return err;
@@ -1368,12 +1366,13 @@ static int null_handle_bio(struct nullb_cmd *cmd)
sector_t sector = bio->bi_iter.bi_sector;
struct bio_vec bvec;
struct bvec_iter iter;
+ bool fua = bio->bi_opf & REQ_FUA

if (bio->bi_opf & REQ_COPY) {
if (op_is_write(bio_op(bio)))
- return nullb_setup_copy_write(nullb, bio,
- bio->bi_opf & REQ_FUA);
- return nullb_setup_copy_read(nullb, bio);
+ return nullb_setup_copy_write(nullb, bio, fua);
+ nullb_setup_copy_read(nullb, bio);
+ return 0;
}

[...]

+struct nullb_copy_token {
+ char subsys[5];
+ struct nullb *nullb;
+ u64 sector_in;
+ u64 sectors;
+};
+

why not use sector_t ?

diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
index c67c098d92fa..ffa4b6a6d19b 100644
--- a/drivers/block/null_blk/null_blk.h
+++ b/drivers/block/null_blk/null_blk.h
@@ -70,8 +70,8 @@ enum {
struct nullb_copy_token {
char subsys[5];
struct nullb *nullb;
- u64 sector_in;
- u64 sectors;
+ sector_t sector_in;
+ sector_t sectors;
};

-ck

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