1. 03 10月, 2012 38 次提交
  2. 01 10月, 2012 1 次提交
  3. 30 9月, 2012 1 次提交
    • M
      vfs: dcache: fix deadlock in tree traversal · 8110e16d
      Miklos Szeredi 提交于
      IBM reported a deadlock in select_parent().  This was found to be caused
      by taking rename_lock when already locked when restarting the tree
      traversal.
      
      There are two cases when the traversal needs to be restarted:
      
       1) concurrent d_move(); this can only happen when not already locked,
          since taking rename_lock protects against concurrent d_move().
      
       2) racing with final d_put() on child just at the moment of ascending
          to parent; rename_lock doesn't protect against this rare race, so it
          can happen when already locked.
      
      Because of case 2, we need to be able to handle restarting the traversal
      when rename_lock is already held.  This patch fixes all three callers of
      try_to_ascend().
      
      IBM reported that the deadlock is gone with this patch.
      
      [ I rewrote the patch to be smaller and just do the "goto again" if the
        lock was already held, but credit goes to Miklos for the real work.
         - Linus ]
      Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
      Cc: Al Viro <viro@ZenIV.linux.org.uk>
      Cc: stable@vger.kernel.org
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      8110e16d