src/patches/suse-2.6.27.31/patches.fixes/percpu_counter_sum_cleanup.patch

   1 From: Mingming Cao <cmm@us.ibm.com>
   2 Subject: percpu counter: clean up percpu_counter_sum_and_set()
   3 References: fate#303783
   4
   5 percpu_counter_sum_and_set() and percpu_counter_sum() is the same except
   6 the former update the global counter after accounting.  Since we are
   7 taking the fbc->lock to calculate the precise value of the
   8 counter in percpu_counter_sum() anyway, it should simply set fbc->count
   9 too, as the percpu_counter_sum_and_set() dose.
  10
  11 This patch merge these two interfaces into one.
  12
  13 Signed-off-by: Mingming Cao <cmm@us.ibm.com>
  14 Acked-by: Jan Kara <jack@suse.cz>
  15 ---
  16  fs/ext4/balloc.c               |    2 +-
  17  include/linux/percpu_counter.h |   12 +++---------
  18  lib/percpu_counter.c           |    8 +++-----
  19  3 files changed, 7 insertions(+), 15 deletions(-)
  20
  21 Index: linux-2.6.27-rc3/fs/ext4/balloc.c
  22 ===================================================================
  23 --- linux-2.6.27-rc3.orig/fs/ext4/balloc.c      2008-08-20 17:25:35.000000000 -0700
  24 +++ linux-2.6.27-rc3/fs/ext4/balloc.c   2008-08-21 14:34:32.000000000 -0700
  25 @@ -1624,7 +1624,7 @@
  26  #ifdef CONFIG_SMP
  27         if (free_blocks - root_blocks < FBC_BATCH)
  28                 free_blocks =
  29 -                       percpu_counter_sum_and_set(&sbi->s_freeblocks_counter);
  30 +                       percpu_counter_sum(&sbi->s_freeblocks_counter);
  31  #endif
  32         if (free_blocks <= root_blocks)
  33                 /* we don't have free space */
  34 Index: linux-2.6.27-rc3/include/linux/percpu_counter.h
  35 ===================================================================
  36 --- linux-2.6.27-rc3.orig/include/linux/percpu_counter.h        2008-08-20 17:25:35.000000000 -0700
  37 +++ linux-2.6.27-rc3/include/linux/percpu_counter.h     2008-08-21 14:34:32.000000000 -0700
  38 @@ -35,7 +35,7 @@
  39  void percpu_counter_destroy(struct percpu_counter *fbc);
  40  void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
  41  void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
  42 -s64 __percpu_counter_sum(struct percpu_counter *fbc, int set);
  43 +s64 __percpu_counter_sum(struct percpu_counter *fbc);
  44
  45  static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
  46  {
  47 @@ -44,19 +44,13 @@
  48
  49  static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
  50  {
  51 -       s64 ret = __percpu_counter_sum(fbc, 0);
  52 +       s64 ret = __percpu_counter_sum(fbc);
  53         return ret < 0 ? 0 : ret;
  54  }
  55
  56 -static inline s64 percpu_counter_sum_and_set(struct percpu_counter *fbc)
  57 -{
  58 -       return __percpu_counter_sum(fbc, 1);
  59 -}
  60 -
  61 -
  62  static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
  63  {
  64 -       return __percpu_counter_sum(fbc, 0);
  65 +       return __percpu_counter_sum(fbc);
  66  }
  67
  68  static inline s64 percpu_counter_read(struct percpu_counter *fbc)
  69 Index: linux-2.6.27-rc3/lib/percpu_counter.c
  70 ===================================================================
  71 --- linux-2.6.27-rc3.orig/lib/percpu_counter.c  2008-08-20 17:25:35.000000000 -0700
  72 +++ linux-2.6.27-rc3/lib/percpu_counter.c       2008-08-21 14:34:32.000000000 -0700
  73 @@ -52,7 +52,7 @@
  74   * Add up all the per-cpu counts, return the result.  This is a more accurate
  75   * but much slower version of percpu_counter_read_positive()
  76   */
  77 -s64 __percpu_counter_sum(struct percpu_counter *fbc, int set)
  78 +s64 __percpu_counter_sum(struct percpu_counter *fbc)
  79  {
  80         s64 ret;
  81         int cpu;
  82 @@ -62,11 +62,9 @@
  83         for_each_online_cpu(cpu) {
  84                 s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
  85                 ret += *pcount;
  86 -               if (set)
  87 -                       *pcount = 0;
  88 +               *pcount = 0;
  89         }
  90 -       if (set)
  91 -               fbc->count = ret;
  92 +       fbc->count = ret;
  93
  94         spin_unlock(&fbc->lock);
  95         return ret;