cvs commit: src/sys/kern vfs_subr.c

[Jeff Roberson]

I tested this by doing a buildworld on a machine with maxvnodes set to
1000.  Needless to say, there was plenty of recycling.  This change in
particular provides a clear path for filesystems to follow when
manipulating vnodes that are found on non usecounted lists.

As per usual, I haven't moved giant at all, I'm just spinning my wheels.
;-)

Cheers,
Jeff

On Sat, 4 Oct 2003, Jeff Roberson wrote:

> jeff        2003/10/04 22:35:42 PDT
>
>   FreeBSD src repository
>
>   Modified files:
>     sys/kern             vfs_subr.c
>   Log:
>    - Rename vcanrecycle() to vtryrecycle() to reflect its new role.
>    - In vtryrecycle() try to vgonel the vnode if all of the previous checks
>      passed.  We won't vgonel if someone has either acquired a hold or usecount
>      or started the vgone process elsewhere.  This is because we may have been
>      removed from the free list while we were inspecting the vnode for
>      recycling.
>    - The VI_TRYLOCK stops two threads from entering getnewvnode() and recycling
>      the same vnode.  To further reduce the likelyhood of this event, requeue
>      the vnode on the tail of the list prior to calling vtryrecycle().  We can
>      not actually remove the vnode from the list until we know that it's
>      going to be recycled because other interlock holders may see the VI_FREE
>      flag and try to remove it from the free list.
>    - Kill a bogus XXX comment.  If XLOCK is set we shouldn't wait for it
>      regardless of MNT_WAIT because the vnode does not actually belong to
>      this filesystem.
>
>   Revision  Changes    Path
>   1.464     +32 -26    src/sys/kern/vfs_subr.c
>