Re: [Bug-tar] Improve sparse file scan through extent_scan module

[Jeff liu]

Hi Eric,

Thanks for your response!

在 2011-8-19，下午9:42， Eric Blake 写道：

> [adding coreutils and bug-gnulib]
> 
> On 08/18/2011 07:33 AM, Jeff liu wrote:
>> Dear developer,
>> 
>> As the fiemap exent-scan module has been added to coreutils for about half 
>> year, and looks it works stable in the past few releases.
>> 
>> Is it possible to make use of it to improve the current tar sparse file scan 
>> procedure?
> 
> We need to migrate the scanner out of coreutils and into gnulib, at which 
> point tar can use it.  Also, be aware that the latest 3.1 kernel and 
> glibc.git have added support for SEEK_HOLE and SEEK_DATA, and we should 
> prefer those higher-level interfaces over the lower-level extent scanners, 
> where possible.
Yes, I recalled Jim have also mentioned to put extent scan module to gnulib 
first.

Consider SEEK_HOLE/SEEK_DATA,  I have submitted a patch to coreutils which can 
be found at:
http://lists.gnu.org/archive/html/bug-coreutils/2011-04/msg00106.html

At that time, it was wrote for ZFS only, I'll take a look at the kernel and 
glibc for this stuff later.

In the meantime, could anyone give a review?

  
> 
>> I'd like to work a patch out if you guys like it.
> 
> Sure, but it starts on the gnulib side.
Thanks,  let's make it present to gnulib first. :)

Regards,
-Jeff
> 
> -- 
> Eric Blake   address@hidden    +1-801-349-2682
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