1. 18 9月, 2014 35 次提交
  2. 15 9月, 2014 3 次提交
    • L
      vfs: avoid non-forwarding large load after small store in path lookup · 9226b5b4
      Linus Torvalds 提交于
      The performance regression that Josef Bacik reported in the pathname
      lookup (see commit 99d263d4 "vfs: fix bad hashing of dentries") made
      me look at performance stability of the dcache code, just to verify that
      the problem was actually fixed.  That turned up a few other problems in
      this area.
      
      There are a few cases where we exit RCU lookup mode and go to the slow
      serializing case when we shouldn't, Al has fixed those and they'll come
      in with the next VFS pull.
      
      But my performance verification also shows that link_path_walk() turns
      out to have a very unfortunate 32-bit store of the length and hash of
      the name we look up, followed by a 64-bit read of the combined hash_len
      field.  That screws up the processor store to load forwarding, causing
      an unnecessary hickup in this critical routine.
      
      It's caused by the ugly calling convention for the "hash_name()"
      function, and easily fixed by just making hash_name() fill in the whole
      'struct qstr' rather than passing it a pointer to just the hash value.
      
      With that, the profile for this function looks much smoother.
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9226b5b4
    • A
      be careful with nd->inode in path_init() and follow_dotdot_rcu() · 4023bfc9
      Al Viro 提交于
      in the former we simply check if dentry is still valid after picking
      its ->d_inode; in the latter we fetch ->d_inode in the same places
      where we fetch dentry and its ->d_seq, under the same checks.
      
      Cc: stable@vger.kernel.org # 2.6.38+
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      4023bfc9
    • A
      don't bugger nd->seq on set_root_rcu() from follow_dotdot_rcu() · 7bd88377
      Al Viro 提交于
      return the value instead, and have path_init() do the assignment.  Broken by
      "vfs: Fix absolute RCU path walk failures due to uninitialized seq number",
      which was Cc-stable with 2.6.38+ as destination.  This one should go where
      it went.
      
      To avoid dummy value returned in case when root is already set (it would do
      no harm, actually, since the only caller that doesn't ignore the return value
      is guaranteed to have nd->root *not* set, but it's more obvious that way),
      lift the check into callers.  And do the same to set_root(), to keep them
      in sync.
      
      Cc: stable@vger.kernel.org # 2.6.38+
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      7bd88377
  3. 14 9月, 2014 2 次提交