Prefaulting for i/o buffers

[Christoph Hellwig]

On Thu, Mar 01, 2012 at 01:16:24PM +0200, Gleb Kurtsou wrote:
> Are you aware of a real "libraries for file systems" VFS example? It
> sounds very interesting but I'm afraid it's going to look good only in
> theory. E.g. locking at file system level (Darwin, Dragonfly BSD) looks
> rather messy (IMHO) and more likely to be bug prone. On the other side
> Linux has optional per file system rename lock making VOP_RENAME
> implementation much easier, while ours is tremendously difficult to do
> right.

All namespace locking in Linux is in the VFS, and it mandatory.  A
filesystem wide lock is only used for cross-directory renames.

A more detailed description is here:

	http://git.kernel.dk/?p=linux.git;a=blob;f=Documentation/filesystems/directory-locking