From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761264Ab2CNRMs (ORCPT ); Wed, 14 Mar 2012 13:12:48 -0400 Received: from mail-yw0-f46.google.com ([209.85.213.46]:35944 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761237Ab2CNRMn (ORCPT ); Wed, 14 Mar 2012 13:12:43 -0400 From: Paolo Bonzini To: linux-kernel@vger.kernel.org Cc: Jens Axboe Subject: [PATCH 1/2] block: tweak rounding of max_discard_sectors Date: Wed, 14 Mar 2012 18:12:27 +0100 Message-Id: <1331745148-24885-2-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.7.7.6 In-Reply-To: <1331745148-24885-1-git-send-email-pbonzini@redhat.com> References: <1331745148-24885-1-git-send-email-pbonzini@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mostly a preparation for the next patch. In principle this fixes an infinite loop if max_discard_sectors < granularity, but that really shouldn't happen. Cc: Jens Axboe Signed-off-by: Paolo Bonzini --- block/blk-lib.c | 9 +++++---- 1 files changed, 5 insertions(+), 4 deletions(-) diff --git a/block/blk-lib.c b/block/blk-lib.c index 2b461b4..d4bb160 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -44,6 +44,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, struct request_queue *q = bdev_get_queue(bdev); int type = REQ_WRITE | REQ_DISCARD; unsigned int max_discard_sectors; + unsigned int granularity; struct bio_batch bb; struct bio *bio; int ret = 0; @@ -53,18 +54,18 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, if (!blk_queue_discard(q)) return -EOPNOTSUPP; + /* Zero-sector (unknown) and one-sector granularities are the same. */ + granularity = max(q->limits.discard_granularity >> 9, 1U); + /* * Ensure that max_discard_sectors is of the proper * granularity */ max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); + max_discard_sectors = round_down(max_discard_sectors, granularity); if (unlikely(!max_discard_sectors)) { /* Avoid infinite loop below. Being cautious never hurts. */ return -EOPNOTSUPP; - } else if (q->limits.discard_granularity) { - unsigned int disc_sects = q->limits.discard_granularity >> 9; - - max_discard_sectors &= ~(disc_sects - 1); } if (flags & BLKDEV_DISCARD_SECURE) { -- 1.7.7.6