On 19-07-11 10:53:24, Chaitanya Kulkarni wrote:
> This patch adds support for memory backed REQ_OP_WRITE_ZEROES
> operations for the null_blk request mode. We introduce two new
> functions where we zeroout the sector(s) using memset which are part
> of the payloadless write-zeroes request.
>
> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx>
> ---
> drivers/block/null_blk_main.c | 45 ++++++++++++++++++++++++++++++++++-
> 1 file changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
> index 65da7c2d93b9..fca011a05277 100644
> --- a/drivers/block/null_blk_main.c
> +++ b/drivers/block/null_blk_main.c
> @@ -725,6 +725,24 @@ static void null_free_sector(struct nullb *nullb, sector_t sector,
> }
> }
>
> +static void null_zero_sector(struct nullb_device *d, sector_t sect,
> + sector_t nr_sects, bool cache)
> +{
> + struct radix_tree_root *root = cache ? &d->cache : &d->data;
> + struct nullb_page *t_page;
> + unsigned int offset;
> + void *dest;
> +
> + t_page = radix_tree_lookup(root, sect >> PAGE_SECTORS_SHIFT);
> + if (!t_page)
> + return;
> +
> + offset = (sect & SECTOR_MASK) << SECTOR_SHIFT;
> + dest = kmap_atomic(t_page->page);
> + memset(dest + offset, 0, SECTOR_SIZE * nr_sects);
> + kunmap_atomic(dest);
> +}
> +
> static struct nullb_page *null_radix_tree_insert(struct nullb *nullb, u64 idx,
> struct nullb_page *t_page, bool is_cache)
> {
> @@ -1026,6 +1044,25 @@ static void null_handle_discard(struct nullb *nullb, sector_t sector, size_t n)
> spin_unlock_irq(&nullb->lock);
> }
>
> +static void null_handle_write_zeroes(struct nullb *nullb, sector_t sector,
> + unsigned int bytes_left)
> +{
> + sector_t nr_sectors;
> + size_t curr_bytes;
> +
> + spin_lock_irq(&nullb->lock);
> + while (bytes_left > 0) {
Hi Chaitanya,
Thanks for your support for this!
I have a simple query here. Is there any recommended rule about using
the function argument to be changed inside of that function like
_bytes_left_? I'm not against it, but I'd like to know if it's okay to
decrement inside of this function in code-style point-of-view.
Thanks!
