lkml.org 
[lkml]   [2016]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/2] dax: fix bdev NULL pointer dereferences
On Sun, Jan 31, 2016 at 10:18:46AM -0800, Dan Williams wrote:
> On Sun, Jan 31, 2016 at 10:07 AM, Matthew Wilcox <willy@linux.intel.com> wrote:
> > Yes. This is just the default implementation of dax_map_pfn() which works
> > for most situations. We can introduce more complex implementations of
> > dax_map_pfn() as necessary. You make another excellent point for why
> > we should store PFNs in the radix tree instead of kaddrs :-)
>
> How much complexity do we want to add in support of an fsync/msync
> mechanism that is not the recommended way to use DAX?

It actually makes the dax_io path much, much simpler. And it's not
primarily about fixing fsync/msync. It also makes the fault path cheaper
in the case where we're refaulting a page that's already been faulted
by another process (or was previously faulted by this process and now
needs to be faulted at a different address).

And it fixes the problem with filesystems that use multiple block_devices.
It also makes DAX much less reliant on buffer heads, which is good for
the problem that Jared raised where he doesn't have a block_device in
an embedded system.

\
 
 \ /
  Last update: 2016-01-31 19:41    [W:1.352 / U:0.380 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site