nullfs changes MFC

[Alfred Perlstein]

By combining vop_settext/unset/get into a single call with parameters "op" and &out (for gettext) you can reduce 3 new vops into a single vop. 

The same can be done for write count vops. 


This will allow you to preserve kbi by reducing the vop additions to 2. 

Sent from my iPhone

On Dec 7, 2012, at 5:01 PM, Konstantin Belousov <kostikbel at gmail.com> wrote:

> Hi,
> I am going to merge latest batch of the nullfs improvements into
> stable/9. This will bring up significant performance enchancements due
> to use of the shared locks for lookups if the lower layer supports it,
> much better caching on the nullfs layer, and proper handling of the text
> segments on the nullfs. Also, it should improve the error recovery and
> some corner cases with locking.
> 
> Unfortunately, the merge would break KBI for VFS, since it needs 5 new
> VOP slots, and only three spares are left. We already are very liberal
> with the VFS KBI, so I do not feel that the merge is not acceptable, due
> to the benefits it brings to the nullfs.
> 
> The merge is available at 
> http://people.freebsd.org/~kib/misc/nullfs_9.1.patch