From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f65.google.com ([209.85.160.65]:34659 "EHLO mail-pl0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755489AbeEHUnV (ORCPT ); Tue, 8 May 2018 16:43:21 -0400 Received: by mail-pl0-f65.google.com with SMTP id ay10-v6so2906165plb.1 for ; Tue, 08 May 2018 13:43:20 -0700 (PDT) Date: Tue, 8 May 2018 13:43:18 -0700 From: Omar Sandoval Subject: Re: [PATCH 1/4] block: break discard submissions into the user defined size Message-ID: <20180508204318.GB27324@vader> References: <1525709615-14395-1-git-send-email-axboe@kernel.dk> <1525709615-14395-2-git-send-email-axboe@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1525709615-14395-2-git-send-email-axboe@kernel.dk> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-xfs@vger.kernel.org, dchinner@redhat.com, hch@lst.de 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 > --- > 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.