Re: [RFC] Heads up on sys_fallocate()

[Ulrich Drepper]

Anton Altaparmakov wrote:
> And that is it.  No zeroing needs to happen at all because we
> have not updated the initialized size of the inode!

When you do it like this, who can the kernel/filesystem *guarantee* that
when the data is written there actually is room on the harddrive?

What you described seems like using truncate/ftruncate to increase the
file's size.  That is not at all what posix_fallocate is for.
posix_fallocate must make sure that the requested blocks on the disk are
reserved (allocated) for the file's use and that at no point in the
future will, say, a msync() fail because a mmap(MAP_SHARED) page has
been written to.

-- 
â Ulrich Drepper â Red Hat, Inc. â 444 Castro St â Mountain View, CA â

Attachment: signature.asc
Description: OpenPGP digital signature