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Re: _IO_file_underflow_mmap read call for atime

From: Ulrich Drepper <drepper at redhat dot com>
To: Roland McGrath <roland at frob dot com>
Cc: GNU libc hackers <libc-hacker at sources dot redhat dot com>
Date: Wed, 31 Jul 2002 16:55:34 -0700
Subject: Re: _IO_file_underflow_mmap read call for atime
References: <20020731231042.57DF21BA18@perdition.linnaean.org>

Roland McGrath wrote:

And it doesn't update atime on read faults as well?  That is permissible
behavior, but not very helpful.  It makes atime pretty useless if it's
possible there are mmap readers.  There could be a process that opened the
file and mmap'd it a year ago, and then later something does a write so
mtime > atime; then if the first process reads the new data, atime remains
unchanged and sometime contemplating mtime vs atime would conclude that the
new data has not been read by anyone.

I don't know enough about the implementation. I only know that the read is needed if mmap happened at fopen time. You can talk to the kernel people.

--
---------------. ,-. 1325 Chesapeake Terrace
Ulrich Drepper \ ,-------------------' \ Sunnyvale, CA 94089 USA
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References:
- Re: _IO_file_underflow_mmap read call for atime
  - From: Roland McGrath

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