1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_BLOCKGROUP_LOCK_H
3 #define _LINUX_BLOCKGROUP_LOCK_H
4 /*
5  * Per-blockgroup locking for ext2 and ext3.
6  *
7  * Simple hashed spinlocking.
8  */
9 
10 #include <linux/spinlock.h>
11 #include <linux/cache.h>
12 
13 #ifdef CONFIG_SMP
14 #define NR_BG_LOCKS	(4 << ilog2(NR_CPUS < 32 ? NR_CPUS : 32))
15 #else
16 #define NR_BG_LOCKS	1
17 #endif
18 
19 struct bgl_lock {
20 	spinlock_t lock;
21 } ____cacheline_aligned_in_smp;
22 
23 struct blockgroup_lock {
24 	struct bgl_lock locks[NR_BG_LOCKS];
25 };
26 
bgl_lock_init(struct blockgroup_lock * bgl)27 static inline void bgl_lock_init(struct blockgroup_lock *bgl)
28 {
29 	int i;
30 
31 	for (i = 0; i < NR_BG_LOCKS; i++)
32 		spin_lock_init(&bgl->locks[i].lock);
33 }
34 
35 static inline spinlock_t *
bgl_lock_ptr(struct blockgroup_lock * bgl,unsigned int block_group)36 bgl_lock_ptr(struct blockgroup_lock *bgl, unsigned int block_group)
37 {
38 	return &bgl->locks[block_group & (NR_BG_LOCKS-1)].lock;
39 }
40 
41 #endif
42