[vdr] Re: Fast forward stops in timeshift mode

[Christoph Rauch <christoph.rauch@pfaffenhofen.de>]

Am Sam, 2003-09-06 um 10.44 schrieb Klaus Schmidinger:
> > Configuration:
> > - vdr 1.2.5pre1
> > - driver CVS 2003-08-23
> > - single DVB-S Nexus 2.1
> > - Kernel 2.4.21
> > - /video on ext3
> Strange...
> The fstat() call in line 864 claimed that the file has an inceased
> size (as calculated in line 871), so one would assume that the
> safe_read() in line 883 should be able to actually read the new
> file content. I would think that the data is _first_ written to the
> end of the file and _then_ the directory entry is updated.
> Could it be that this is not the case? Can the directory entry
> be updated _before_ the data is appended to the file? That wouldn't
> make sense to me...
Indeed strange. As ext3 is a journalling fs, the changes should be
atomic and thus always in sync with each other. Of course it could
happen if the kernel has a bug, which I can not confirm... the last
really annoying ext3 bug has been fixed about a year ago. And it was
only triggered by SMP-machines. Since then I had no problems with files
of all kinds and sizes.

@Oliver: SMP or singe processor machine? 
@Klaus: How is VDR programmed. Is the function which apparently causes
the error thread-safe and/or using only thread-safe functions? I never
dug really deep in your code and since I have had cable the last year :(
I didn't use it either. Pity. ;)

Just thinking loud: 
- After googling around a little bit if found this
http://lwn.net/2002/0214/a/dirsync.php3 , but I am not sure that it
applys here as "append" is not affected by this.

-- 
Christoph Rauch



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