Bad file access on the rise

Miloslav Trma─Ź mitr at volny.cz
Fri Jun 7 20:14:36 UTC 2013


On Fri, Jun 7, 2013 at 10:05 PM, Colin Walters <walters at verbum.org> wrote:
> On Fri, 2013-06-07 at 20:42 +0100, Matthew Garrett wrote:
>
>> Without further analysis, it doesn't tell us much. Does the code attempt
>> to open a file O_NOATIME and then fall back to trying it without?
>
> It's likely:
> https://bugzilla.gnome.org/show_bug.cgi?id=680326

Is there any more rationale for the change available?

(IMHO only very special applications should use O_NOATIME; if it is
not predictable which accesses do/don't update atime, the field
completely loses its value.  The definition we have is "time of last
access" (see (man stat.h) for the POSIX wording), not "time of last
user-initiated access" or "time used for $specific_purpose"; given the
lack of $specific_purpose it's difficult to say what accesses
should/should not be excluded but that's, I think, even more of a
reason to stick to the formal definition.  OTOH mlocate does use
O_NOATIME so that atime isn't updated for every modified directory,
and the line in the sand between updatedb and thumbnail generation
admittedly isn't all that clear.)
    Mirek


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