On Tue, Feb 20, 2007 at 11:01:50AM -0500, Trond Myklebust wrote:
> We don't try to resolve "conflicting" writes between ordinary mmap() and
> write(), so why should we be doing it for mmap and O_DIRECT?
Yes we do -- both writes will succeed. More importantly, if one modifies
the first 512 bytes of a page and the other modifies the last 512 bytes of
the page, both writes will show up in the completed result. This is not the
case with the -EIO bailout.
> mmap() is designed to violate the ordinary mutex locks for write(), so
> if a conflict arises, whether it be with O_DIRECT or ordinary writes
> then it is a case of "last writer wins".
Except that we're not handling cases like the one mentioned above, which
is quite broken.
-ben
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