Re: [PATCH v2] block: simplify blksize_bits() implementation
From: Bart Van Assche
Date: Sat Oct 29 2022 - 23:33:33 EST
On 10/29/22 20:25, Dawei Li wrote:
On Sat, Oct 29, 2022 at 08:00:58PM -0700, Bart Van Assche wrote:
On 10/29/22 19:17, Dawei Li wrote:
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 57ed49f20d2e..7b537afe8b38 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1349,12 +1349,7 @@ static inline int blk_rq_aligned(struct request_queue *q, unsigned long addr,
/* assumes size > 256 */
static inline unsigned int blksize_bits(unsigned int size)
{
- unsigned int bits = 8;
- do {
- bits++;
- size >>= 1;
- } while (size > 256);
- return bits;
+ return order_base_2((size + SECTOR_SIZE - 1) >> SECTOR_SHIFT) + SECTOR_SHIFT;
}
Why the rounding ("+ SECTOR_SIZE - 1")? The blksize_bits() argument should
be an argument of two.
Yeah, that's what's supposed to be.
But I thought maybe a "just in case" is more robust?
Should we consider these corner cases(!is_power_of_2())?
I don't think that the Linux kernel supports block sizes that are not a
power of two. Hence my request to leave out the rounding code. Keeping
that code would be misleading because it would suggest that the
blksize_bits() argument can be something else than a power of two.
Thanks,
Bart.