Date: Thu, 28 Apr 2011 08:57:53 -0700 (PDT) From: "Pedro F. Giffuni" <giffunip@yahoo.com> To: Kostik Belousov <kostikbel@gmail.com> Cc: svn-src-head@freebsd.org, John Baldwin <jhb@freebsd.org> Subject: Re: svn commit: r221166 - in head/sys: fs/ext2fs modules/ext2fs Message-ID: <433267.83376.qm@web113513.mail.gq1.yahoo.com>
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> There is no dependencies for ext2fs, the FFS comments talks about SU. You are right ... I will have to clean that up. It was not easy to keep all SU stuff from getting in. > Also, I am unsure what the resulting semantic of O_DIRECTIO for ext2 > is ? UFS tries to eliminate any use of buffer cache for O_DIRECTIO > case, up to the mapping of user pages into pbuf to perform the > actual i/o. In ext2 case, it seems we will just destroy the buffers > after using them for i/o. Is it useful ? We do not support the complete direct_io stuff (not even in UFS). In ext2fs we are only avoiding double caching: it is assumed that the application (usually databases) knows why it's setting O_DIRECTIO and do their own caching. From what I discussed with Tor Egge it is useful. cheers, Pedro.
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