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
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 *
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
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