CVS commit: src/sys/sys

["Jason R Thorpe" <thorpej%netbsd.org@localhost>]

Module Name:    src
Committed By:   thorpej
Date:           Wed Oct 20 03:09:45 UTC 2021

Modified Files:
        src/sys/sys: param.h

Log Message:
Overhaul of the EVFILT_VNODE kevent(2) filter:

- Centralize vnode kevent handling in the VOP_*() wrappers, rather than
  forcing each individual file system to deal with it (except VOP_RENAME(),
  because VOP_RENAME() is a mess and we currently have 2 different ways
  of handling it; at least it's reasonably well-centralized in the "new"
  way).
- Add support for NOTE_OPEN, NOTE_CLOSE, NOTE_CLOSE_WRITE, and NOTE_READ,
  compatible with the same events in FreeBSD.
- Track which kevent notifications clients are interested in receiving
  to avoid doing work for events no one cares about (avoiding, e.g.
  taking locks and traversing the klist to send a NOTE_WRITE when
  someone is merely watching for a file to be deleted, for example).

In support of the above:

- Add support in vnode_if.sh for specifying PRE- and POST-op handlers,
  to be invoked before and after vop_pre() and vop_post(), respectively.
  Basic idea from FreeBSD, but implemented differently.
- Add support in vnode_if.sh for specifying CONTEXT fields in the
  vop_*_args structures.  These context fields are used to convey information
  between the file system VOP function and the VOP wrapper, but do not
  occupy an argument slot in the VOP_*() call itself.  These context fields
  are initialized and subsequently interpreted by PRE- and POST-op handlers.
- Version VOP_REMOVE(), uses the a context field for the file system to report
  back the resulting link count of the target vnode.  Return this in tmpfs,
  udf, nfs, chfs, ext2fs, lfs, and ufs.

NetBSD 9.99.92.


To generate a diff of this commit:
cvs rdiff -u -r1.704 -r1.705 src/sys/sys/param.h

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