hi, Farnum, Thank you very much! :-) On Thu, 2010-12-02 at 00:11 +0800, Gregory Farnum wrote: > On Tue, Nov 30, 2010 at 7:50 PM, wchen <wchen@xxxxxxxxxxxxx> wrote: > > hi, Sage, > > > > I'm reading the source code of ceph. Recently I'm very confused with > > struct InodeCap's issued, implemented, wanted fields. I just have a > > preliminary understanding of them, but what's the exact difference > > between them? there are lots of code to reflect the relation between > > them. Can you explain it for me? or any documents about it? > Unfortunately we don't have a lot of documentation about the source > code itself. Sage's thesis (which is available on the website) is the > best resource, and does describe caps some. > > Briefly, caps are short for capabilities. They are issued by the MDS > to clients to describe what the client is allowed to do with an inode > and its associated file. There are capabilities to, for instance, let > the client buffer writes, cache reads, and adjust certain kinds of > metadata (mtime, et al). > The wanted capabilities are caps the client wants but doesn't have. > Issued caps are ones the client has been granted, and (IIRC) > implemented caps are a subset of the issued caps describing which caps > the client has actually made use of. It's useful for determining > whether the client has dirty metadata and whatnot. :) > -Greg -- best regards, Kevin Chen (éå) -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
