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 16:21:34 +0200 Message-ID: <4FF2FFEE.4000401@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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120703140048.GC11272@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 16:00, Vivek Goyal ha scritto: >> > >> > Ah, interesting, I missed it completely. I guess it's because queue/ >> > directories only exist for full disks, and the correct alignment varies >> > for each partition. So this patch is unnecessary. > Partition discard_alignments are available in > /sys/block///discard_alignment. Yes. If it were in queue/, it wouldn't be available. > That raises an interesting question for patch3. If the discard is happening to > a partition, shouldn't you be looking at partition discard_alignment > instead of always looking at queue discard_alignment? Good point! Like this? diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index ba43f40..3530764 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1125,6 +1125,16 @@ static inline int queue_limit_discard_alignment(struct queue_limits *lim, sector & (lim->discard_granularity - 1); } +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; /* * Ensure that max_discard_sectors is of the proper Paolo