On Tuesday 02 December 2008 21:16:13 Daniel Phillips wrote:

quoted text
> I only had to make one hack to core vfs to make this work.  Essentially,

> we are changing the dentry cache from a volatile, read only cache to a

> writeback cache which is entirely consistent on its own, as opposed to

> just being an accelerator.  We always knew this was possible, because

> that is how RAMFS works.  But I needed to make it work when the cache

> is backed by a filesystem.  All I had to do here is add one new method,

> to prevent the dentry cache from forcibly removing a dentry from the

> cache that has been unlinked, but which is still in used for some hard

> to understand reason.  With my new hook (d_ops->hide) the dentry just

> stays in cache as a negative dentry and we take a reference count on it

> to make sure it does not disappear before our code has a chance to find

> it and remove the underlying directory entry.

Hi Daniel,

  While I'm certainly not qualified to comment on the _content_ of the patch, I

have been watching Linux filesystem flamewars for a while... I _strongly_

suggest that you write to linux-fsdevel@vger about these VFS changes, and

sooner rather than later. (It probably would be a good idea to directly CC at

least Al Viro and Christoph Hellwig; Ted Ts'o, Christoph Lameter, Linus, and

Andrew Morton are also good candidates.) Tux3 looks very promising, and I

would hate to see it get tied up in avoidable VFS battles when it's otherwise

ready for merging.
Thanks,

-- BKS
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