linux-stable/include/linux/blockgroup_lock.h
Eric Biggers 7c5f6b320b blockgroup_lock.h: simplify definition of NR_BG_LOCKS
We can use ilog2() to more easily produce the desired NR_BG_LOCKS.  This
works because ilog2() is evaluated at compile-time when its argument is
a compile-time constant.

I did not change the chosen NR_BG_LOCKS values.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
2016-09-15 18:29:06 -04:00

40 lines
771 B
C

#ifndef _LINUX_BLOCKGROUP_LOCK_H
#define _LINUX_BLOCKGROUP_LOCK_H
/*
* Per-blockgroup locking for ext2 and ext3.
*
* Simple hashed spinlocking.
*/
#include <linux/spinlock.h>
#include <linux/cache.h>
#ifdef CONFIG_SMP
#define NR_BG_LOCKS (4 << ilog2(NR_CPUS < 32 ? NR_CPUS : 32))
#else
#define NR_BG_LOCKS 1
#endif
struct bgl_lock {
spinlock_t lock;
} ____cacheline_aligned_in_smp;
struct blockgroup_lock {
struct bgl_lock locks[NR_BG_LOCKS];
};
static inline void bgl_lock_init(struct blockgroup_lock *bgl)
{
int i;
for (i = 0; i < NR_BG_LOCKS; i++)
spin_lock_init(&bgl->locks[i].lock);
}
static inline spinlock_t *
bgl_lock_ptr(struct blockgroup_lock *bgl, unsigned int block_group)
{
return &bgl->locks[block_group & (NR_BG_LOCKS-1)].lock;
}
#endif