cvs commit: src/sys/ufs/ffs ffs_softdep.c

[Don Lewis]

truckman    2005-09-29 21:50:26 UTC

  FreeBSD src repository

  Modified files:
    sys/ufs/ffs          ffs_softdep.c 
  Log:
  After a rmdir()ed directory has been truncated, force an update of
  the directory's inode after queuing the dirrem that will decrement
  the parent directory's link count.  This will force the update of
  the parent directory's actual link to actually be scheduled.  Without
  this change the parent directory's actual link count would not be
  updated until ufs_inactive() cleared the inode of the newly removed
  directory, which might be deferred indefinitely.  ufs_inactive()
  will not be called as long as any process holds a reference to the
  removed directory, and ufs_inactive() will not clear the inode if
  the link count is non-zero, which could be the result of an earlier
  system crash.
  
  If a background fsck is run before the update of the parent directory's
  actual link count has been performed, or at least scheduled by
  putting the dirrem on the leaf directory's inodedep id_bufwait list,
  fsck will corrupt the file system by decrementing the parent
  directory's effective link count, which was previously correct
  because it already took the removal of the leaf directory into
  account, and setting the actual link count to the same value as the
  effective link count after the dangling, removed, leaf directory
  has been removed.  This happens because fsck acts based on the
  actual link count, which will be too high when fsck creates the
  file system snapshot that it references.
  
  This change has the fortunate side effect of more quickly cleaning
  up the large number dirrem structures that linger for an extended
  time after the removal of a large directory tree.  It also fixes a
  potential problem with the shutdown of the syncer thread timing out
  if the system is rebooted immediately after removing a large directory
  tree.
  
  Submitted by:   tegge
  MFC after:      3 days
  
  Revision  Changes    Path
  1.185     +2 -0      src/sys/ufs/ffs/ffs_softdep.c