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From: Neil Brown <neilb@suse.de>
To: Shaohua Li <shli@fb.com>
Cc: linux-raid@vger.kernel.org, Kernel-team@fb.com,
	songliubraving@fb.com, hch@infradead.org,
	dan.j.williams@intel.com
Subject: Re: [PATCH 4/6] md: don't export log device
Date: Thu, 08 Oct 2015 15:16:41 +1100	[thread overview]
Message-ID: <87bnca6lli.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <20151008031644.GA3063621@devbig084.prn1.facebook.com>

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Shaohua Li <shli@fb.com> writes:
>> 
>> Neither of these chunks should be needed.
>> ->raid_disk of an active devices is only set to -1 if ->hot_remove_disk
>> succeeds.
>> You have make ->hot_remove_disk fail for Journal devices, so ->raid_disk
>> will be >= 0.
>
> I agree the raid5_remove_disk part is superficial, I fixed in an updated
> patch. I still didn't get the point what can prevent a journal disk is
> removed. Currently the raid_disk is always -1 for journal disk. If it
> should be >=0, what value it should be? We give journal disk a special
> role '0xfffd' currently.

Oh, are we leaving the ->raid_disk at -1 for the journal?  I hadn't
noticed that.  I don't feel comfortable it.  Too much code assumes that
<0 means "not in use".

Probably set it to 0, and add a check to setup_conf(), and adjust the
check in run().  md_update_sb() probably need to be careful of journals
too (to not change ->recovery_offset).
I wonder what 'slot_show' should report for the journal.... maybe
"journal"??

NeilBrown

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  reply	other threads:[~2015-10-08  4:16 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-04 16:20 [PATCH 0/6] raid5-cache fixes Shaohua Li
2015-10-04 16:20 ` [PATCH 1/6] md: show journal for journal disk in disk state sysfs Shaohua Li
2015-10-04 16:20 ` [PATCH 2/6] raid5-cache: move reclaim stop to quiesce Shaohua Li
2015-10-04 16:20 ` [PATCH 3/6] raid5-cache: add trim support for log Shaohua Li
2015-10-08  1:53   ` Neil Brown
2015-10-04 16:20 ` [PATCH 4/6] md: don't export log device Shaohua Li
2015-10-08  1:57   ` Neil Brown
2015-10-08  3:16     ` Shaohua Li
2015-10-08  4:16       ` Neil Brown [this message]
2015-10-08  4:31         ` Shaohua Li
2015-10-08  6:04           ` Neil Brown
2015-10-13 12:07             ` Christoph Hellwig
2015-10-13 20:41               ` Neil Brown
2015-10-04 16:20 ` [PATCH 5/6] md: set In_Sync for log disk Shaohua Li
2015-10-04 16:20 ` [PATCH 6/6] raid5-cache: IO error handling Shaohua Li
2015-10-08  2:10 ` [PATCH 0/6] raid5-cache fixes Neil Brown
2015-10-08  2:56   ` Shaohua Li
2015-10-08  3:18     ` Neil Brown
2015-10-08  3:24       ` Shaohua Li

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