hi,
On Sun, Sep 02, 2001 at 04:53:39AM +1000, monkeyiq wrote:
>
> I was reading over this again:
> http://www.osnews.com/story.php?news_id=69
> ...
> It's an extent-based filesystem, has features like delayed allocation,
> space preallocation and space coallescing on deletion, and goes to
> great lengths in attempting to layout files using the largest extents
> possible (an "extent" being an offset and a length within a file).
Pfft - don't listen to that guy!
>
> So I was reading xfs_mkfile.c line 188 of 277
> flck.l_whence = SEEK_SET;
> flck.l_start = 0LL;
> flck.l_len = size;
> #if 0
> (void)ioctl(fd, XFS_IOC_RESVSP64, &flck);
>
Hmm.... well I see the kernel code is all there. I'm
guessing this was just overlooked during porting, so I've
pushed in the change (mkfile does prealloc conditionally
only, via the -p option).
> I presume that this XFS_IOC_RESVSP64 tells XFS to reserve off a chunk of
> space for future use by the file.
Yes, pretty much.
> Are the ioctl() calls for XFS documented anywhere?
No, but they should be. Some of the documentation exists in
the IRIX syssgi man page - I'll probably slap that into xfs(5)
at some point.
cheers.
--
Nathan
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