include/linux/blockgroup_lock.h

   1 #ifndef _LINUX_BLOCKGROUP_LOCK_H
   2 #define _LINUX_BLOCKGROUP_LOCK_H
   3 /*
   4  * Per-blockgroup locking for ext2 and ext3.
   5  *
   6  * Simple hashed spinlocking.
   7  */
   8
   9 #include <linux/spinlock.h>
  10 #include <linux/cache.h>
  11
  12 #ifdef CONFIG_SMP
  13 #define NR_BG_LOCKS     (4 << ilog2(NR_CPUS < 32 ? NR_CPUS : 32))
  14 #else
  15 #define NR_BG_LOCKS     1
  16 #endif
  17
  18 struct bgl_lock {
  19         spinlock_t lock;
  20 } ____cacheline_aligned_in_smp;
  21
  22 struct blockgroup_lock {
  23         struct bgl_lock locks[NR_BG_LOCKS];
  24 };
  25
  26 static inline void bgl_lock_init(struct blockgroup_lock *bgl)
  27 {
  28         int i;
  29
  30         for (i = 0; i < NR_BG_LOCKS; i++)
  31                 spin_lock_init(&bgl->locks[i].lock);
  32 }
  33
  34 static inline spinlock_t *
  35 bgl_lock_ptr(struct blockgroup_lock *bgl, unsigned int block_group)
  36 {
  37         return &bgl->locks[block_group & (NR_BG_LOCKS-1)].lock;
  38 }
  39
  40 #endif