On 2/7/22 23:13, Nitesh Shetty wrote:
> Add device limits as sysfs entries,
> - copy_offload (READ_WRITE)
> - max_copy_sectors (READ_ONLY)
Why read-only ? With the name as you have it, it seems to be the soft
control for the max size of copy operations rather than the actual
device limit. So it would be better to align to other limits like max
sectors/max_hw_sectors and have:
max_copy_sectors (RW)
max_hw_copy_sectors (RO)
> - max_copy_ranges_sectors (READ_ONLY)
> - max_copy_nr_ranges (READ_ONLY)
Same for these.
>
> copy_offload(= 0), is disabled by default. This needs to be enabled if
> copy-offload needs to be used.
How does this work ? This limit will be present for a DM device AND the
underlying devices of the DM target. But "offload" applies only to the
underlying devices, not the DM device...
Also, since this is not an underlying device limitation but an on/off
switch, this should probably be moved to a request_queue boolean field
or flag bit, controlled with sysfs.
> max_copy_sectors = 0, indicates the device doesn't support native copy.
>
> Signed-off-by: Nitesh Shetty <nj.shetty@xxxxxxxxxxx>
> Signed-off-by: SelvaKumar S <selvakuma.s1@xxxxxxxxxxx>
> Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
> ---
> block/blk-settings.c | 4 ++++
> block/blk-sysfs.c | 51 ++++++++++++++++++++++++++++++++++++++++++
> include/linux/blkdev.h | 12 ++++++++++
> 3 files changed, 67 insertions(+)
>
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index b880c70e22e4..818454552cf8 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -57,6 +57,10 @@ void blk_set_default_limits(struct queue_limits *lim)
> lim->misaligned = 0;
> lim->zoned = BLK_ZONED_NONE;
> lim->zone_write_granularity = 0;
> + lim->copy_offload = 0;
> + lim->max_copy_sectors = 0;
> + lim->max_copy_nr_ranges = 0;
> + lim->max_copy_range_sectors = 0;
> }
> EXPORT_SYMBOL(blk_set_default_limits);
>
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index 9f32882ceb2f..dc68ae6b55c9 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -171,6 +171,48 @@ static ssize_t queue_discard_granularity_show(struct request_queue *q, char *pag
> return queue_var_show(q->limits.discard_granularity, page);
> }
>
> +static ssize_t queue_copy_offload_show(struct request_queue *q, char *page)
> +{
> + return queue_var_show(q->limits.copy_offload, page);
> +}
> +
> +static ssize_t queue_copy_offload_store(struct request_queue *q,
> + const char *page, size_t count)
> +{
> + unsigned long copy_offload;
> + ssize_t ret = queue_var_store(©_offload, page, count);
> +
> + if (ret < 0)
> + return ret;
> +
> + if (copy_offload && q->limits.max_copy_sectors == 0)
> + return -EINVAL;
> +
> + if (copy_offload)
> + q->limits.copy_offload = BLK_COPY_OFFLOAD;
> + else
> + q->limits.copy_offload = 0;
> +
> + return ret;
> +}
> +
> +static ssize_t queue_max_copy_sectors_show(struct request_queue *q, char *page)
> +{
> + return queue_var_show(q->limits.max_copy_sectors, page);
> +}
> +
> +static ssize_t queue_max_copy_range_sectors_show(struct request_queue *q,
> + char *page)
> +{
> + return queue_var_show(q->limits.max_copy_range_sectors, page);
> +}
> +
> +static ssize_t queue_max_copy_nr_ranges_show(struct request_queue *q,
> + char *page)
> +{
> + return queue_var_show(q->limits.max_copy_nr_ranges, page);
> +}
> +
> static ssize_t queue_discard_max_hw_show(struct request_queue *q, char *page)
> {
>
> @@ -597,6 +639,11 @@ QUEUE_RO_ENTRY(queue_nr_zones, "nr_zones");
> QUEUE_RO_ENTRY(queue_max_open_zones, "max_open_zones");
> QUEUE_RO_ENTRY(queue_max_active_zones, "max_active_zones");
>
> +QUEUE_RW_ENTRY(queue_copy_offload, "copy_offload");
> +QUEUE_RO_ENTRY(queue_max_copy_sectors, "max_copy_sectors");
> +QUEUE_RO_ENTRY(queue_max_copy_range_sectors, "max_copy_range_sectors");
> +QUEUE_RO_ENTRY(queue_max_copy_nr_ranges, "max_copy_nr_ranges");
> +
> QUEUE_RW_ENTRY(queue_nomerges, "nomerges");
> QUEUE_RW_ENTRY(queue_rq_affinity, "rq_affinity");
> QUEUE_RW_ENTRY(queue_poll, "io_poll");
> @@ -643,6 +690,10 @@ static struct attribute *queue_attrs[] = {
> &queue_discard_max_entry.attr,
> &queue_discard_max_hw_entry.attr,
> &queue_discard_zeroes_data_entry.attr,
> + &queue_copy_offload_entry.attr,
> + &queue_max_copy_sectors_entry.attr,
> + &queue_max_copy_range_sectors_entry.attr,
> + &queue_max_copy_nr_ranges_entry.attr,
> &queue_write_same_max_entry.attr,
> &queue_write_zeroes_max_entry.attr,
> &queue_zone_append_max_entry.attr,
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index efed3820cbf7..f63ae50f1de3 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -51,6 +51,12 @@ extern struct class block_class;
> /* Doing classic polling */
> #define BLK_MQ_POLL_CLASSIC -1
>
> +/* Define copy offload options */
> +enum blk_copy {
> + BLK_COPY_EMULATE = 0,
> + BLK_COPY_OFFLOAD,
> +};
> +
> /*
> * Maximum number of blkcg policies allowed to be registered concurrently.
> * Defined here to simplify include dependency.
> @@ -253,6 +259,10 @@ struct queue_limits {
> unsigned int discard_granularity;
> unsigned int discard_alignment;
> unsigned int zone_write_granularity;
> + unsigned int copy_offload;
> + unsigned int max_copy_sectors;
> + unsigned short max_copy_range_sectors;
> + unsigned short max_copy_nr_ranges;
>
> unsigned short max_segments;
> unsigned short max_integrity_segments;
> @@ -562,6 +572,7 @@ struct request_queue {
> #define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */
> #define QUEUE_FLAG_HCTX_ACTIVE 28 /* at least one blk-mq hctx is active */
> #define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */
> +#define QUEUE_FLAG_COPY 30 /* supports copy offload */
Then what is the point of max_copy_sectors limit ? You can test support
by the device by looking at max_copy_sectors != 0, no ? This flag is
duplicated information.
I would rather use it for the on/off switch for the copy offload,
removing the copy_offload limit.
>
> #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
> (1 << QUEUE_FLAG_SAME_COMP) | \
> @@ -585,6 +596,7 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
> #define blk_queue_io_stat(q) test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
> #define blk_queue_add_random(q) test_bit(QUEUE_FLAG_ADD_RANDOM, &(q)->queue_flags)
> #define blk_queue_discard(q) test_bit(QUEUE_FLAG_DISCARD, &(q)->queue_flags)
> +#define blk_queue_copy(q) test_bit(QUEUE_FLAG_COPY, &(q)->queue_flags)
> #define blk_queue_zone_resetall(q) \
> test_bit(QUEUE_FLAG_ZONE_RESETALL, &(q)->queue_flags)
> #define blk_queue_secure_erase(q) \
--
Damien Le Moal
Western Digital Research
