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Re: [PATCH 4/5] dax: use sb_issue_zerout instead of calling dax_clear_se

To: "Verma, Vishal L" <vishal.l.verma@xxxxxxxxx>
Subject: Re: [PATCH 4/5] dax: use sb_issue_zerout instead of calling dax_clear_sectors
From: Jan Kara <jack@xxxxxxx>
Date: Mon, 4 Apr 2016 14:09:49 +0200
Cc: "jack@xxxxxxx" <jack@xxxxxxx>, "linux-block@xxxxxxxxxxxxxxx" <linux-block@xxxxxxxxxxxxxxx>, "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>, "linux-mm@xxxxxxxxx" <linux-mm@xxxxxxxxx>, "viro@xxxxxxxxxxxxxxxxxx" <viro@xxxxxxxxxxxxxxxxxx>, "Williams, Dan J" <dan.j.williams@xxxxxxxxx>, "axboe@xxxxxx" <axboe@xxxxxx>, "akpm@xxxxxxxxxxxxxxxxxxxx" <akpm@xxxxxxxxxxxxxxxxxxxx>, "linux-nvdimm@xxxxxxxxxxxx" <linux-nvdimm@xxxxxxxxxxxx>, "linux-fsdevel@xxxxxxxxxxxxxxx" <linux-fsdevel@xxxxxxxxxxxxxxx>, "ross.zwisler@xxxxxxxxxxxxxxx" <ross.zwisler@xxxxxxxxxxxxxxx>, "linux-ext4@xxxxxxxxxxxxxxx" <linux-ext4@xxxxxxxxxxxxxxx>, "Wilcox, Matthew R" <matthew.r.wilcox@xxxxxxxxx>, "david@xxxxxxxxxxxxx" <david@xxxxxxxxxxxxx>
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User-agent: Mutt/1.5.24 (2015-08-30)
On Fri 01-04-16 19:17:52, Verma, Vishal L wrote:
> On Wed, 2016-03-30 at 09:49 +0200, Jan Kara wrote:
> > On Tue 29-03-16 18:57:16, Verma, Vishal L wrote:
> > > 
> > > 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... :)
> > Actually, my patches for page fault locking remove zeroing from
> > dax_insert_mapping() and __dax_pmd_fault() - the zeroing now happens
> > from
> > the filesystem only and the zeroing in those two functions is just a
> > dead
> > code...
> 
> That should make things easier! Do you have a tree I could merge in to
> get this? (WIP is ok as we know that my series will depend on yours..)
> or, if you can distill out that patch on a 4.6-rc1 base, I could carry
> it in my series too (your v2's 3/10 doesn't apply on 4.6-rc1..)

I'll CC you on the next posting of the series which I want to do this week.

                                                                Honza

-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR

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