K 10
svn:author
V 3
jhb
K 8
svn:date
V 27
2009-01-20T19:01:59.498401Z
K 7
svn:log
V 1223
MFC: Close several races with using shared vnode locks for pathname lookups
with UFS and enable shared lookups for UFS.
- Change the name cache to fail lookups with EBADF if a directory vnode
  is recycled while it waits for a lock upgrade.
- Rework the locking of the dirhash to use an sx lock and reference count
  on each hash structure.  Using an sx lock instead of a mutex allows the
  lock to be held across disk I/O closing a number of races when using
  shared vnode locks that were previously handled by exclusive vnode
  locks.
- Remove the 'i_ino' and 'i_reclen' fields from the i-node.  i_ino is now
  a local variable in ufs_lookup(), and i_reclen is not needed since
  ufs_dirremove() always has the entire block holding the directory
  entry in memory when it updates the directory.
- 'i_diroff' and 'i_offset' are now local variables in ufs_lookup().
  'i_diroff' is updated after a successful lookup.
- Only set i_offset in the parent directory's i-node during a lookup for
  non-LOOKUP operations.
- Remove the LOOKUP_SHARED option.  One can set vfs.lookup_shared to 1
  in either loader.conf or sysctl.conf instead.  The default setting for
  vfs.lookup_shared is not changed and remains off by default.

END