Messages in this thread Patch in this message | | | Date | Thu, 15 Apr 2021 12:44:30 -0700 | From | Eric Biggers <> | Subject | Re: [PATCH v2 4/8] block: introduce bio_required_sector_alignment() |
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On Thu, Mar 25, 2021 at 09:26:05PM +0000, Satya Tangirala wrote: > This function returns the required alignment for the number of sectors in > a bio. In particular, the number of sectors passed to bio_split() must be > aligned to this value. > > Signed-off-by: Satya Tangirala <satyat@google.com> > --- > block/blk.h | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/block/blk.h b/block/blk.h > index 3b53e44b967e..5ef207a6d34c 100644 > --- a/block/blk.h > +++ b/block/blk.h > @@ -261,6 +261,18 @@ static inline unsigned int bio_allowed_max_sectors(struct request_queue *q) > return round_down(UINT_MAX, queue_logical_block_size(q)) >> 9; > } > > +/* > + * The required sector alignment for a bio. The number of sectors in any bio > + * that's constructed/split must be aligned to this value.
What does "constructed" mean in this context?
> + */ > +static inline unsigned int bio_required_sector_alignment(struct bio *bio) > +{ > + struct request_queue *q = bio->bi_bdev->bd_disk->queue; > + > + return max(queue_logical_block_size(q) >> SECTOR_SHIFT, > + blk_crypto_bio_sectors_alignment(bio)); > +}
It would be slightly simpler to use bdev_logical_block_size(bio->bi_bdev) instead of queue_logical_block_size(bio->bi_bdev->bd_disk->queue).
Also, if there's interest in avoiding the branch implied by the max() here, it would be possible to take advantage of the values being powers of 2 as follows:
static inline unsigned int bio_required_sector_alignment(struct bio *bio) { unsigned int alignmask = (bdev_logical_block_size(q) >> SECTOR_SHIFT) - 1;
alignmask |= blk_crypto_bio_sectors_alignment(bio) - 1; return alignmask + 1; }
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