linux-ext4 - Re: [PATCH 4/5] dax: use sb_issue_zerout instead of calling dax_clear

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Date:	Tue, 29 Mar 2016 18:57:16 +0000
From:	"Verma, Vishal L" <vishal.l.verma@...el.com>
To:	"Williams, Dan J" <dan.j.williams@...el.com>
CC:	"linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
	"xfs@....sgi.com" <xfs@....sgi.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
	"axboe@...com" <axboe@...com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"ross.zwisler@...ux.intel.com" <ross.zwisler@...ux.intel.com>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	"Wilcox, Matthew R" <matthew.r.wilcox@...el.com>,
	"david@...morbit.com" <david@...morbit.com>,
	"jack@...e.cz" <jack@...e.cz>
Subject: Re: [PATCH 4/5] dax: use sb_issue_zerout instead of calling
 dax_clear_sectors

On Mon, 2016-03-28 at 16:34 -0700, Dan Williams wrote:

<>

> Seems kind of sad to fail the fault due to a bad block when we were
> going to zero it anyway, right?  I'm not seeing a compelling reason to
> keep any zeroing in fs/dax.c.

Agreed - but how do we do this? clear_pmem needs to be able to clear an
arbitrary number of bytes, but to go through the driver, we'd need to
send down a bio? If only the driver had an rw_bytes like interface that
could be used by anyone... :)