On 5/8/18 2:43 PM, Omar Sandoval wrote: > On Mon, May 07, 2018 at 10:13:32AM -0600, Jens Axboe wrote: >> Don't build discards bigger than what the user asked for, if the >> user decided to limit the size by writing to 'discard_max_bytes'. >> >> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> >> --- >> block/blk-lib.c | 7 ++++--- >> 1 file changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/block/blk-lib.c b/block/blk-lib.c >> index a676084d4740..7417d617091b 100644 >> --- a/block/blk-lib.c >> +++ b/block/blk-lib.c >> @@ -62,10 +62,11 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, >> unsigned int req_sects; >> sector_t end_sect, tmp; >> >> - /* Make sure bi_size doesn't overflow */ >> - req_sects = min_t(sector_t, nr_sects, UINT_MAX >> 9); >> + /* Issue in chunks of the user defined max discard setting */ >> + req_sects = min_t(sector_t, nr_sects, >> + q->limits.max_discard_sectors); >> > > Some drivers, including nvme, do > > blk_queue_max_discard_sectors(q, UINT_MAX) > > That means q->limits.max_discard_sectors can be UINT_MAX, and > > bio->bi_iter.bi_size = req_sects << 9; > > will overflow. We should probably cap max_discard_sectors at > UINT_MAX >> 9 in a prep patch. Probably better to just keep the local overflow check, I'll do that. Thanks for spotting it! -- Jens Axboe
