Date: Thu, 28 Jun 2007 00:14:34 +0800 From: "Howard Su" <howard0su@gmail.com> To: fs@freebsd.org Cc: danchi@freebsd.org Subject: unionfs requirement for tmpfs Message-ID: <f126fae00706270914x47035950qfef3b64c289a40dc@mail.gmail.com>
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Hi All, I am working on tmpfs to make it support unionfs. I think I understand the theory of the unionfs. However I want someone can give me some info regarding the implementation details, like ISWHITEOUT, DOWHITEOUT op. As far as I know, a fs can be used as upper level and lower level fs of a unionfs. The requirement should be different: 1. As a upper level (which will be changed. I am more interested to make tmpfs support this) what is the requirement? So far, based on my code reading on ufs/unionfs, I need implement VOP_WHITEOUT with three OPs: LOOKUP, DELETE, CREATE. what' the expctation of input and output, the code reading can not give me a clear answer. ufs use some hacking way to call into ufs code itself to make the logic unclear to me. 2. As a lower level fs. what's the requirement? I have no idea totally. Share me whatever you know, please. -- -Howard
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