> On 4/15/21 3:38 AM, Changheun Lee wrote: > > @@ -167,6 +168,7 @@ void blk_queue_max_hw_sectors(struct request_queue *q, > > unsigned int max_hw_secto > > max_sectors = round_down(max_sectors, > > limits->logical_block_size >> SECTOR_SHIFT); > > limits->max_sectors = max_sectors; > > + limits->bio_max_bytes = max_sectors << SECTOR_SHIFT; > > > > q->backing_dev_info->io_pages = max_sectors >> (PAGE_SHIFT - 9); > > } > > Can the new shift operation overflow? If so, how about using > check_shl_overflow()?
OK, I'll check. > > > @@ -538,6 +540,8 @@ int blk_stack_limits(struct queue_limits *t, struct > > queue_limits *b, > > { > > unsigned int top, bottom, alignment, ret = 0; > > > > + t->bio_max_bytes = min_not_zero(t->bio_max_bytes, b->bio_max_bytes); > > + > > t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors); > > t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors); > > t->max_dev_sectors = min_not_zero(t->max_dev_sectors, > > b->max_dev_sectors); > > The above will limit bio_max_bytes for all stacked block devices, which > is something we do not want. I propose to set t->bio_max_bytes to > UINT_MAX in blk_stack_limits() and to let the stacked driver (e.g. > dm-crypt) decide whether or not to lower that value. > Actually, bio size should be limited in dm-crypt too. Because almost I/O from user space will be gone to dm-crypt first. I/O issue timing will be delayed if bio size is not limited in dm-crypt. Do you have any idea to decide whether takes lower bio max size, or not in the stacked driver? Add a flag to decide this in driver layer like before? Or insert code manually in each stacked driver if it is needed? > > diff --git a/include/linux/bio.h b/include/linux/bio.h > > index d0246c92a6e8..e5add63da3af 100644 > > --- a/include/linux/bio.h > > +++ b/include/linux/bio.h > > @@ -106,6 +106,8 @@ static inline void *bio_data(struct bio *bio) > > return NULL; > > } > > > > +extern unsigned int bio_max_size(struct bio *bio); > > You may want to define bio_max_size() as an inline function in bio.h > such that no additional function calls are introduced in the hot path. Thanks, I'll try. > > Thanks, > > Bart.