From: Christoph Hellwig <hch@infradead.org>
To: Liu Bo <bo.li.liu@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-btrfs@vger.kernel.org, Miao Xie <miaox@cn.fujitsu.com>,
Jan Schmidt <list.btrfs@jan-o-sch.net>
Subject: Re: bi_vcnt checks for repair
Date: Sat, 12 Nov 2016 09:34:01 -0800 [thread overview]
Message-ID: <20161112173401.GA27521@infradead.org> (raw)
In-Reply-To: <20161111193151.GA30930@dhcp-whq-twvpn-1-vpnpool-10-159-131-21.vpn.oracle.com>
On Fri, Nov 11, 2016 at 11:31:51AM -0800, Liu Bo wrote:
> Try to explain it a bit, the following assumes that the data that's
> being read has at least one copy in another device,
>
> if a read bio contains two pages and the second one is failing on
> checksum check, then we get into bio_readpage_error, in which it finds
> this bio has two pages, so it creats a new bio (so-called validation
> request) which only includes the fail-on-checksum victim page and issues
> it with REQ_FAILFAST_DEV to read the page again in hope of passing the
> checksum check, if it stills fails somehow, it comes into
> bio_readpage_error again to do another try but along with a different
> copy.
>
> Overall, this bi_vcnt is to tell whether the bio is a normal one and a
> validation one. If the validation bio got merged somehow, then we need
> to do something to prevent that from happening.
Can't we just set a different end_io handler for the two cases?
prev parent reply other threads:[~2016-11-12 17:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-10 20:06 bi_vcnt checks for repair Christoph Hellwig
2016-11-11 19:31 ` Liu Bo
2016-11-12 17:34 ` Christoph Hellwig [this message]
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