From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [dm-devel] [PATCH v2 1/3] block: add sysfs entry for discard_alignment Date: Tue, 03 Jul 2012 16:40:40 +0200 Message-ID: <4FF30468.30407@redhat.com> References: <1341235225-27551-1-git-send-email-pbonzini@redhat.com> <1341235225-27551-2-git-send-email-pbonzini@redhat.com> <20120703023442.GB3586@redhat.com> <4FF2DCB1.2090704@redhat.com> <20120703140048.GC11272@redhat.com> <4FF2FFEE.4000401@redhat.com> <20120703143949.GE11272@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120703143949.GE11272@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Vivek Goyal Cc: linux-kernel@vger.kernel.org, axboe@kernel.dk, snitzer@redhat.com, martin.petersen@oracle.com, david@fromorbit.com, xfs@oss.sgi.com, dm-devel@redhat.com, hch@lst.de List-Id: dm-devel.ids Il 03/07/2012 16:39, Vivek Goyal ha scritto: >> > +static inline int bdev_discard_alignment(struct block_device *bdev) >> > +{ >> > + struct request_queue *q = bdev_get_queue(bdev); >> > + >> > + if (bdev != bdev->bd_contains) >> > + return bdev->bd_part->discard_alignment; >> > + >> > + return q->limits.discard_alignment; >> > +} >> > + >> > static inline unsigned int queue_discard_zeroes_data(struct request_queue *q) >> > { >> > if (q->limits.max_discard_sectors && q->limits.discard_zeroes_data == 1) >> > diff --git a/block/blk-lib.c b/block/blk-lib.c >> > index b2bde5c..77d8869 100644 >> > --- a/block/blk-lib.c >> > +++ b/block/blk-lib.c >> > @@ -58,7 +58,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector, >> > /* Zero-sector (unknown) and one-sector granularities are the same. */ >> > granularity = max(q->limits.discard_granularity >> 9, 1U); >> > mask = granularity - 1; >> > - alignment = (q->limits.discard_alignment >> 9) & mask; >> > + alignment = bdev_discard_alignment(bdev) >> 9; > Why are you removing AND with mask operation? I don't see any AND > operation being done in bdev_discard_alignment(). For partitions it is done by queue_limits_discard_alignment. For disks, it shouldn't be necessary at all but I can leave it. paolo