Re: [PATCH] tmpfs: support SEEK_DATA and SEEK_HOLE (reprise)

From: Jim Meyering
Date: Thu Nov 29 2012 - 15:17:52 EST


Dave Chinner wrote:
...
>> So, yes, GNU cp will soon use this feature.
>
> It would be nice if utilities like grep used it, too, because having
> grep burn gigabytes of memory scanning holes in large files and
> then going OOM is, well, kind of nasty:
>
> $ xfs_io -f -c "truncate 1t" blah
> $ ls -l
> total 0
> -rw-r--r-- 1 dave dave 1.0T Nov 30 06:42 blah
> $ grep foo blah
> grep: memory exhausted
> $ $ grep -V
> grep (GNU grep) 2.12

Hi Dave,

Yes, adapting grep is also on the road map.
That precise case was one of my arguments for making SEEK_DATA/SEEK_HOLE
support more widespread.
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