From: Sanidhya Solanki <jpage.lkml@gmail.com>
To: David Sterba <dsterba@suse.cz>
Cc: clm@fb.com, jbacik@fb.com, dsterba@suse.com,
linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] BTRFS: Runs the xor function if a Block has failed
Date: Wed, 30 Dec 2015 21:15:44 -0500 [thread overview]
Message-ID: <20151230211544.32bc337e@gmail.com> (raw)
In-Reply-To: <20151230171826.GG4227@twin.jikos.cz>
On Wed, 30 Dec 2015 18:18:26 +0100
David Sterba <dsterba@suse.cz> wrote:
> That's just the comment copied, the changelog does not explain why
> it's ok to do just the run_xor there. It does not seem trivial to me.
> Please describe that the end result after the code change is expected.
In the RAID 6 case after a failure, we discover that the failure
affected the entire P stripe, without any bad data occurring. Hence, we
xor the previously stored parity data to return the data that was lost
in the P stripe failure.
The xor-red data is from the parity blocks. Hence, we are left with
recovered data belonging to the P stripe.
If there is an error during the completion of the xor (provided by the
patch ), we got to the cleanup function.
Hope that is satisfactory.
next prev parent reply other threads:[~2015-12-31 6:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-30 6:28 [PATCH] BTRFS: Runs the xor function if a Block has failed Sanidhya Solanki
2015-12-30 17:18 ` David Sterba
2015-12-31 2:15 ` Sanidhya Solanki [this message]
2016-01-05 9:22 ` David Sterba
2016-01-05 10:03 ` Sanidhya Solanki
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