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1da177e4 LT |
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 | ||
1da177e4 LT |
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 | ||
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 | int i; | |
47 | ||
48 | for (i = 0; i < NR_BG_LOCKS; i++) | |
49 | spin_lock_init(&bgl->locks[i].lock); | |
50 | } | |
51 | ||
52 | /* | |
53 | * The accessor is a macro so we can embed a blockgroup_lock into different | |
54 | * superblock types | |
55 | */ | |
c644f0e4 PE |
56 | static inline spinlock_t * |
57 | bgl_lock_ptr(struct blockgroup_lock *bgl, unsigned int block_group) | |
58 | { | |
59 | return &bgl->locks[(block_group) & (NR_BG_LOCKS-1)].lock; | |
60 | } | |
1da177e4 LT |
61 | |
62 | #endif |