Re: [Bug-tar] Detection of sparse files is broken on btrfs

[Joerg Schilling]

Tim Kientzle <address@hidden> wrote:

> I'm not entirely sure I understand the above.
>
> It sounds like someone is claiming that:
>
> * Archiving programs should know about the *timing* of filesystem 
> implementations  (60s here for btrfs, something else for <new filesystem 
> XYZ>?)
>
> * And specifically request the OS to fsync() files before trusting the 
> metadata

This is exactly the reason, why btrfs (in case it behaves as claimed) seems to
be be in conflict with POSIX.

POSIX requires that stat() returns cached meta data instead of probably out of 
date information from the background medium. In other words: It is not 
allowed to return different data before and after a sync() or fsync() call.

Jörg

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