src/patches/suse-2.6.27.31/patches.suse/dlm-remove-extra-blocking-callback-check.patch

   1 From: David Teigland <teigland@redhat.com>
   2 commit 03339696314fffb95dafb349b84243358e945ce6
   3 Author: David Teigland <teigland@redhat.com>
   4 Date:   Mon Dec 8 17:14:10 2008 -0600
   5 Subject: dlm: remove extra blocking callback check
   6
   7     Just before delivering a blocking callback (bast), the dlm_astd
   8     thread checks again that the granted mode of the lkb actually
   9     blocks the mode requested by the bast.  The idea behind this was
  10     originally that the granted mode may have changed since the bast
  11     was queued, making the callback now unnecessary.  Reasons for
  12     removing this extra check are:
  13     - dlm_astd doesn't lock the rsb before reading the lkb grmode, so
  14       it's not technically safe (this removes the long standing FIXME)
  15     - after running some tests, it doesn't appear the check ever actually
  16       eliminates a bast
  17     - delivering an unnecessary blocking callback isn't a bad thing and
  18       can happen anyway
  19
  20 Signed-off-by: David Teigland <teigland@redhat.com>
  21 Signed-off-by: Coly Li <coly.li@suse.de>
  22
  23 diff --git a/fs/dlm/ast.c b/fs/dlm/ast.c
  24 index 30c11f3..09b167d 100644
  25 --- a/fs/dlm/ast.c
  26 +++ b/fs/dlm/ast.c
  27 @@ -89,13 +89,8 @@ static void process_asts(void)
  28                 if ((type & AST_COMP) && cast)
  29                         cast(lkb->lkb_astparam);
  30
  31 -               /* FIXME: Is it safe to look at lkb_grmode here
  32 -                  without doing a lock_rsb() ?
  33 -                  Look at other checks in v1 to avoid basts. */
  34 -
  35                 if ((type & AST_BAST) && bast)
  36 -                       if (!dlm_modes_compat(lkb->lkb_grmode, bmode))
  37 -                               bast(lkb->lkb_astparam, bmode);
  38 +                       bast(lkb->lkb_astparam, bmode);
  39
  40                 /* this removes the reference added by dlm_add_ast
  41                    and may result in the lkb being freed */