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Re: [PATCH 4/4] Remove broken posix_fallocate, posix_falllocate64 fallback code [BZ#15661]

From: Paul Eggert <eggert at cs dot ucla dot edu>
To: Florian Weimer <fweimer at redhat dot com>, libc-alpha at sourceware dot org
Date: Wed, 06 May 2015 15:48:38 -0700
Subject: Re: [PATCH 4/4] Remove broken posix_fallocate, posix_falllocate64 fallback code [BZ#15661]
Authentication-results: sourceware.org; auth=none
References: <20150424134516 dot 6795441F484D0 at oldenburg dot str dot redhat dot com> <554927F9 dot 7080509 at redhat dot com> <5549C097 dot 50505 at redhat dot com>

Florian Weimer wrote:

Maybe we could remove the write loop and perform only an ftruncate call
which (hopefully) increases the file size.  This would take care of the
O_APPEND issue and remove most of the races.


I like this idea.

Using posix_fallocate to
avoid ENOSPC later would not work, but with thin provisioning,
deduplicating storage and compression going around these days, I don't
think writing zero blocks has that effect in practice anyway


That's right.

(particularly not on NFS).


It's in draft NFS v4.2 as the ALLOCATE operation; see:

https://tools.ietf.org/html/draft-ietf-nfsv4-minorversion2-38

This is pretty much bleeding-edge of course.

Follow-Ups:
- Re: [PATCH 4/4] Remove broken posix_fallocate, posix_falllocate64 fallback code [BZ#15661]
  - From: Rich Felker

References:
- Re: [PATCH 4/4] Remove broken posix_fallocate, posix_falllocate64 fallback code [BZ#15661]
  - From: Carlos O'Donell
- Re: [PATCH 4/4] Remove broken posix_fallocate, posix_falllocate64 fallback code [BZ#15661]
  - From: Florian Weimer

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