Question about Cyrus, ext3, and Linux kernel 2.4.18 bug
qralston+ml.info-cyrus at andrew.cmu.edu
Fri Apr 18 16:02:15 EDT 2003
On 2003-04-16 at 22:38:15-0400 Lawrence Greenfield <leg+ at andrew.cmu.edu> wrote:
> Sigh. This is a well known problem with ext2. It is impossible for
> any application to maintain sane consistency guarantees with ext2 in
> the default async mode. (It's not clear mounting ext2 in "sync"
> mode is sufficient for any serious application.)
It's usually a big performance hit, yes.
> All the Linux journalling filesystems implement softupdates-like
> semantics and do not require an fsync() on a directory to force
> filenames to disk. There are various reasons why doing so is
> unreasonable, which is why MTAs and Cyrus refuse to do so.
Could you enumerate the reasons?
> I can't think of any sane reason why ext3 authors would want to
> weaken the semantics they export to applications now.
Don't count on it. There's a fair amount of precedence in Linux that
previous behavior will be cheerfully tossed out the window if it
results in what Linus et. al. think is a better system. Unless
there's a relevant standard which asserts that fsync() must implement
softupdate-like behavior (I know of none), it's open to change.
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