Line data Source code
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 :
14 : /*
15 : * We want a power-of-two. Is there a better way than this?
16 : */
17 :
18 : #if NR_CPUS >= 32
19 : #define NR_BG_LOCKS 128
20 : #elif NR_CPUS >= 16
21 : #define NR_BG_LOCKS 64
22 : #elif NR_CPUS >= 8
23 : #define NR_BG_LOCKS 32
24 : #elif NR_CPUS >= 4
25 : #define NR_BG_LOCKS 16
26 : #elif NR_CPUS >= 2
27 : #define NR_BG_LOCKS 8
28 : #else
29 : #define NR_BG_LOCKS 4
30 : #endif
31 :
32 : #else /* CONFIG_SMP */
33 : #define NR_BG_LOCKS 1
34 : #endif /* CONFIG_SMP */
35 :
36 : struct bgl_lock {
37 : spinlock_t lock;
38 : } ____cacheline_aligned_in_smp;
39 1 :
40 : struct blockgroup_lock {
41 : struct bgl_lock locks[NR_BG_LOCKS];
42 : };
43 :
44 : static inline void bgl_lock_init(struct blockgroup_lock *bgl)
45 : {
46 0 : int i;
47 0 :
48 0 : for (i = 0; i < NR_BG_LOCKS; i++)
49 0 : spin_lock_init(&bgl->locks[i].lock);
50 0 : }
51 :
52 : /*
53 : * The accessor is a macro so we can embed a blockgroup_lock into different
54 : * superblock types
55 0 : */
56 : static inline spinlock_t *
57 : bgl_lock_ptr(struct blockgroup_lock *bgl, unsigned int block_group)
58 : {
59 1272 : return &bgl->locks[(block_group) & (NR_BG_LOCKS-1)].lock;
60 : }
61 1 :
62 : #endif
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