From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Mike Snitzer <snitzer@redhat.com>
Cc: Ming Lei <ming.lei@canonical.com>,
device-mapper development <dm-devel@redhat.com>,
Christoph Hellwig <hch@lst.de>, Alasdair Kergon <agk@redhat.com>,
Lars Ellenberg <drbd-dev@lists.linbit.com>,
Philip Kelleher <pjk1939@linux.vnet.ibm.com>,
Christoph Hellwig <hch@infradead.org>,
Kent Overstreet <kent.overstreet@gmail.com>,
Nitin Gupta <ngupta@vflare.org>,
Ming Lin <ming.l@ssi.samsung.com>,
Oleg Drokin <oleg.drokin@intel.com>,
Al Viro <viro@zeniv.linux.org.uk>, Ming Lin <mlin@kernel.org>,
Jens Axboe <axboe@kernel.dk>,
axboe@fb.com, Andreas Dilger <andreas.dilger@intel.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Geoff Levand <geoff@infradead.org>, Jiri Kosina <jkosina@suse.cz>,
lkml <linux-kernel@vger.kernel.org>, Jim Paris <jim@jtan.com>,
Minchan Kim <minchan@kernel.org>, Joe Thornber <ejt@redhat.com>,
Dongsu Park <dpark@posteo.net>,
drbd-user@lists.linbit.com
Subject: Re: [Drbd-dev] [PATCH v5 01/11] block: make generic_make_request handle arbitrarily sized bios
Date: Mon, 10 Aug 2015 12:22:07 -0400 [thread overview]
Message-ID: <yq1si7rgllc.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <20150810150216.GA22719@redhat.com> (Mike Snitzer's message of "Mon, 10 Aug 2015 11:02:17 -0400")
>>>>> "Mike" == Mike Snitzer <snitzer@redhat.com> writes:
Mike> Shouldn't we also be using MAX_BIO_SECTORS in
Mike> blkdev_issue_write_same (instead of UINT_MAX >> 9)?
The granularity of WRITE SAME is always 1 logical block and there is no
reason to round it down to the next power of two.
+/*
+ * Ensure that max discard sectors doesn't overflow bi_size and hopefully
+ * it is of the proper granularity as long as the granularity is a power
+ * of two.
+ */
+#define MAX_DISCARD_SECTORS ((1U << 31) >> 9)
+
That's fine for SATA since we're already capping at 2TB minus change.
But it means we'll be capping unnecessarily on SCSI. And larger range
counts are impending in SATA as well.
So this goes back to my original comment: The only place there can be a
discard granularity is for SCSI UNMAP. And consequently, we should only
enforce alignment and granularity when that code path is taken in sd.c.
I'm OK with Ming's patch series in general. Let's leave the discard cap
at UINT_MAX and I'll twiddle the rest in SCSI.
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2015-08-10 16:22 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-06 7:44 [Drbd-dev] [PATCH v5 01/11] block: make generic_make_request handle arbitrarily sized bios Ming Lin
2015-07-06 7:44 ` [Drbd-dev] [PATCH v5 08/11] block: kill merge_bvec_fn() completely Ming Lin
2015-07-31 19:23 ` [Drbd-dev] [PATCH v5 01/11] block: make generic_make_request handle arbitrarily sized bios Mike Snitzer
2015-07-31 21:19 ` Ming Lin
2015-07-31 21:38 ` Mike Snitzer
2015-08-01 6:58 ` Ming Lin
2015-08-01 16:33 ` Mike Snitzer
2015-08-03 5:58 ` Ming Lin
2015-08-04 11:36 ` Christoph Hellwig
2015-08-05 6:03 ` Ming Lin
2015-08-07 7:30 ` Christoph Hellwig
2015-08-07 23:40 ` Ming Lin
2015-09-11 13:20 ` Kent Overstreet
2015-08-08 5:17 ` Ming Lin
2015-09-11 13:20 ` Kent Overstreet
2015-08-08 12:35 ` Christoph Hellwig
2015-09-11 13:21 ` [Drbd-dev] [dm-devel] " Hannes Reinecke
2015-09-11 13:21 ` Kent Overstreet
2015-09-11 13:22 ` Hannes Reinecke
[not found] ` <20150807000004.GB30757@moria.home.lan>
2015-08-07 7:30 ` [Drbd-dev] " Christoph Hellwig
2015-08-08 16:19 ` [Drbd-dev] [dm-devel] " Martin K. Petersen
2015-08-09 5:59 ` Ming Lin
2015-08-09 6:41 ` Christoph Hellwig
2015-08-09 6:55 ` Ming Lin
2015-08-09 7:01 ` Christoph Hellwig
2015-08-09 7:18 ` Ming Lin
2015-08-10 15:02 ` [Drbd-dev] " Mike Snitzer
2015-08-10 16:14 ` Ming Lin
2015-08-10 16:18 ` Ming Lin
2015-08-10 16:40 ` Martin K. Petersen
2015-08-10 18:13 ` Mike Snitzer
2015-08-10 22:30 ` Ming Lin
2015-08-10 16:22 ` Martin K. Petersen [this message]
2015-08-10 18:18 ` Ming Lin
2015-08-11 2:00 ` Martin K. Petersen
2015-08-11 2:41 ` Mike Snitzer
2015-08-11 17:36 ` Martin K. Petersen
2015-08-11 17:47 ` Mike Snitzer
2015-08-11 18:01 ` [Drbd-dev] [dm-devel] " Martin K. Petersen
2015-09-11 13:22 ` [Drbd-dev] " Kent Overstreet
2015-08-11 14:08 ` Mike Snitzer
2015-08-11 17:49 ` Martin K. Petersen
2015-08-11 18:05 ` Martin K. Petersen
2015-08-11 20:56 ` Ming Lin
2015-08-12 0:24 ` Martin K. Petersen
2015-08-12 4:41 ` Ming Lin
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