From: snitzer@redhat.com (Mike Snitzer)
Subject: [PATCH v3 07/12] md: suspend i/o during runtime blk_integrity_unregister
Date: Tue, 12 Jan 2016 21:59:33 -0500 [thread overview]
Message-ID: <20160113025933.GA30612@redhat.com> (raw)
In-Reply-To: <CAPcyv4i8ynO8xjyML86k2cM-djvvKvSAS-dgR2XcaUwhgYC0dg@mail.gmail.com>
On Tue, Jan 12 2016 at 9:24pm -0500,
Dan Williams <dan.j.williams@intel.com> wrote:
> On Tue, Jan 12, 2016@6:14 PM, NeilBrown <neilb@suse.com> wrote:
> >
> > Hi Dan,
> >
> > Somewhat belatedly I am testing this code, and it deadlocks. Which is
> > obvious once I think about it.
> >
> > raid10_add_disk() is called from
> > raid10d -> md_check_recovery -> remove_and_add_spares
> >
> > so this call to mddev_suspend() will block raid10d until all pending IO
> > completes. But raid10d might be needed to complete some IO -
> > particularly in the case of errors. I don't know exactly what is
> > deadlocking in my test, but it doesn't surprise me that something does.
>
> Ugh.
>
> > Can you explain in more detail what needs to be synchronised here? If
> > the synchronisation doesn't happen, what can do wrong?
> > Because I cannot imagine what this might actually be protecting against.
>
> My thinking is that if the integrity profile changes while i/o is in
> flight we can get spurious errors. For example when enabling
> integrity a checksum for in-flight commands will be missing, so wait
> for those to complete.
DM avoids this because it doesn't allow changing the integrity profile
once one is established.
next prev parent reply other threads:[~2016-01-13 2:59 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-21 17:19 [PATCH v3 00/12] Simplify block integrity registration v3 Dan Williams
2015-10-21 17:19 ` [PATCH v3 01/12] block: Move integrity kobject to struct gendisk Dan Williams
2015-10-21 17:19 ` [PATCH v3 02/12] block: Consolidate static integrity profile properties Dan Williams
2015-10-21 17:19 ` [PATCH v3 03/12] block: Reduce the size of struct blk_integrity Dan Williams
2015-10-21 17:19 ` [PATCH v3 04/12] block: Export integrity data interval size in sysfs Dan Williams
2015-10-21 17:19 ` [PATCH v3 05/12] block: Inline blk_integrity in struct gendisk Dan Williams
2015-10-21 17:19 ` [PATCH v3 06/12] md, dm, scsi, nvme, libnvdimm: drop blk_integrity_unregister() at shutdown Dan Williams
2016-01-14 10:32 ` Sagi Grimberg
2015-10-21 17:20 ` [PATCH v3 07/12] md: suspend i/o during runtime blk_integrity_unregister Dan Williams
2016-01-13 2:14 ` NeilBrown
2016-01-13 2:24 ` Dan Williams
2016-01-13 2:59 ` Mike Snitzer [this message]
2016-01-13 3:10 ` NeilBrown
2016-01-13 5:11 ` Dan Williams
2016-01-13 19:51 ` Mike Snitzer
2016-01-14 0:00 ` [PATCH] md/raid: only permit hot-add of compatible integrity profiles Dan Williams
2016-01-14 0:00 ` Dan Williams
2016-01-14 0:56 ` NeilBrown
2016-01-14 0:56 ` NeilBrown
2015-10-21 17:20 ` [PATCH v3 08/12] nvme: suspend i/o during runtime blk_integrity_unregister Dan Williams
2016-01-14 10:32 ` Sagi Grimberg
2015-10-21 17:20 ` [PATCH v3 09/12] block: generic request_queue reference counting Dan Williams
2016-01-14 10:35 ` Sagi Grimberg
2015-10-21 17:20 ` [PATCH v3 10/12] block: move blk_integrity to request_queue Dan Williams
2016-01-14 10:36 ` Sagi Grimberg
2015-10-21 17:20 ` [PATCH v3 11/12] block: blk_flush_integrity() for bio-based drivers Dan Williams
2016-01-14 10:36 ` Sagi Grimberg
2015-10-21 17:20 ` [PATCH v3 12/12] block, libnvdimm, nvme: provide a built-in blk_integrity nop profile Dan Williams
2016-01-14 10:37 ` Sagi Grimberg
2015-10-22 15:26 ` [PATCH v3 00/12] Simplify block integrity registration v3 Christoph Hellwig
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