[Devel] [PATCH 4/4] blk-cbt: Don't open-code DIV_ROUND_UP macro

[Alexander Atanasov]

On 27.01.23 13:34, Nikolay Borisov wrote:
> Using the macro makes the code more explicit and somewhat easier to
> comprehend.
> 
> Signed-off-by: Nikolay Borisov <nikolay.borisov at virtuozzo.com>
> ---
>   block/blk-cbt.c | 11 ++++++-----
>   1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/block/blk-cbt.c b/block/blk-cbt.c
> index 68c7f71ec3a0..967533a2a7a3 100644
> --- a/block/blk-cbt.c
> +++ b/block/blk-cbt.c
> @@ -18,11 +18,12 @@
>   #include <linux/pagemap.h>
>   #include <linux/vmalloc.h>
>   #include <linux/log2.h>
> +#include <linux/math.h>
>   #include <asm/atomic.h>
>   #include <asm/uaccess.h>
>   
>   #define CBT_MAX_EXTENTS	512
> -#define NR_PAGES(bits) (((bits) + PAGE_SIZE*8 - 1) / (PAGE_SIZE*8))
> +#define NR_PAGES(bits) DIV_ROUND_UP((bits), PAGE_SIZE*8)
>   #define BITS_PER_PAGE		(1UL << (PAGE_SHIFT + 3))
>   
>   #define CBT_PAGE_MISSED (struct page *)(0x1)
> @@ -230,7 +231,7 @@ static void blk_cbt_add(struct request_queue *q, blkcnt_t start, blkcnt_t len)
>   
>   	if (unlikely(test_bit(CBT_ERROR, &cbt->flags)))
>   		goto out_rcu;
> -	end = (start + len + (1 << cbt->block_bits) -1) >> cbt->block_bits;
> +	end = DIV_ROUND_UP(start + len, 1 << cbt->block_bits);
>   	start >>= cbt->block_bits;
>   	len = end - start;
>   	if (unlikely(test_bit(CBT_NOCACHE, &cbt->flags))) {
> @@ -272,7 +273,7 @@ static struct cbt_info* do_cbt_alloc(struct request_queue *q, __u8 *uuid,
>   		return ERR_PTR(-ENOMEM);
>   
>   	cbt->block_bits = ilog2(blocksize);
> -	cbt->block_max  = (size + blocksize - 1) >> cbt->block_bits;
> +	cbt->block_max  = DIV_ROUND_UP(size, blocksize);
>   	spin_lock_init(&cbt->lock);
>   	memcpy(cbt->uuid, uuid, sizeof(cbt->uuid));
>   	cbt->cache = alloc_percpu(struct cbt_extent);
> @@ -587,7 +588,7 @@ void blk_cbt_update_size(struct block_device *bdev)
>   		return;
>   	}
>   	bsz = 1 << cbt->block_bits;
> -	if ((new_sz + bsz - 1) >> cbt->block_bits <= cbt->block_max)
> +	if (DIV_ROUND_UP(new_sz, bsz) <= cbt->block_max)
>   		goto err_mtx;
>   
>   	new = do_cbt_alloc(q, cbt->uuid, new_sz, bsz);
> @@ -945,7 +946,7 @@ static int cbt_ioc_set(struct block_device *bdev, struct blk_user_cbt_info __use
>   		struct cbt_extent ex;
>   
>   		ex.start  = cur_ex->ce_physical >> cbt->block_bits;
> -		ex.len  = (cur_ex->ce_length + (1 << cbt->block_bits) -1) >> cbt->block_bits;
> +		ex.len  = DIV_ROUND_UP(cur_ex->ce_length, 1 << cbt->block_bits);
>   		if (ex.start > q->cbt->block_max ||
>   		    ex.start + ex.len > q->cbt->block_max ||
>   		    ex.len == 0) {


LGTM - macro is definitely more clear. The only difference that comes 
from the macro is shift vs division but none of the changes are at fast 
paths.

-- 
Regards,
Alexander Atanasov