src/patches/suse-2.6.27.31/patches.fixes/ocfs2-1.4-git-b4c30de39a2596503e888a7b47d19792f25913d6

   1 From: Jan Kara <jack@suse.cz>
   2 Subject: ocfs2: Fix lock inversion in ocfs2_local_read_info()
   3 Patch-mainline: 2.6.31
   4
   5 This function is called with dqio_mutex held but it has to acquire lock
   6 from global quota file which ranks above this lock. This is not deadlockable
   7 lock inversion since this code path is take only during mount when noone
   8 else can race with us but let's clean this up to silence lockdep.
   9
  10 We just drop the dqio_mutex in the beginning of the function and reacquire
  11 it in the end since we don't need it - noone can race with us at this moment.
  12
  13 Signed-off-by: Jan Kara <jack@suse.cz>
  14 ---
  15  fs/ocfs2/quota_local.c |    5 +++++
  16  1 file changed, 5 insertions(+)
  17
  18 --- a/fs/ocfs2/quota_local.c
  19 +++ b/fs/ocfs2/quota_local.c
  20 @@ -647,6 +647,9 @@ static int ocfs2_local_read_info(struct
  21         struct ocfs2_quota_recovery *rec;
  22         int locked = 0;
  23
  24 +       /* We don't need the lock and we have to acquire quota file locks
  25 +        * which will later depend on this lock */
  26 +       mutex_unlock(&sb_dqopt(sb)->dqio_mutex);
  27         info->dqi_maxblimit = 0x7fffffffffffffffLL;
  28         info->dqi_maxilimit = 0x7fffffffffffffffLL;
  29         oinfo = kmalloc(sizeof(struct ocfs2_mem_dqinfo), GFP_NOFS);
  30 @@ -725,6 +728,7 @@ static int ocfs2_local_read_info(struct
  31                 goto out_err;
  32         }
  33
  34 +       mutex_lock(&sb_dqopt(sb)->dqio_mutex);
  35         return 0;
  36  out_err:
  37         if (oinfo) {
  38 @@ -738,6 +742,7 @@ out_err:
  39                 kfree(oinfo);
  40         }
  41         brelse(bh);
  42 +       mutex_lock(&sb_dqopt(sb)->dqio_mutex);
  43         return -1;
  44  }
  45