CVS commit: src/sys

["Andrew Doran" <ad%netbsd.org@localhost>]

Module Name:    src
Committed By:   ad
Date:           Sat May 30 20:16:14 UTC 2020

Modified Files:
        src/sys/kern: vfs_cache.c vfs_lookup.c
        src/sys/sys: namei.src

Log Message:
A couple of small changes to lookup that cut 5-10% system time from
"build.sh release" on my test system:

- Crossing mount points during lookup is slow because the set up for, and
  act of doing VFS_ROOT() is quite involved.  Use the name cache to help
  with this.  Cache an "impossible" zero-length name with covered vnodes,
  that points to the root of the file system mounted there.  Use it to cross
  mounts.  When cache_purge() is called on either of the vnodes involved the
  cache entry will disappear.  All of the needed calls for that are already
  in place (vnode reclaim, unmount, etc).

- In lookup_fastforward(), if the the last component has been found and the
  parent directory (searchdir) is not going to be returned, then don't get a
  reference to it.


To generate a diff of this commit:
cvs rdiff -u -r1.145 -r1.146 src/sys/kern/vfs_cache.c
cvs rdiff -u -r1.220 -r1.221 src/sys/kern/vfs_lookup.c
cvs rdiff -u -r1.57 -r1.58 src/sys/sys/namei.src

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.