Btrfs: Replace the big fs_mutex with a collection of other locks
[linux-2.6] / fs / btrfs / bit-radix.c
1 /*
2  * Copyright (C) 2007 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18
19 #include "bit-radix.h"
20
21 #define BIT_ARRAY_BYTES 256
22 #define BIT_RADIX_BITS_PER_ARRAY ((BIT_ARRAY_BYTES - sizeof(unsigned long)) * 8)
23
24 extern struct kmem_cache *btrfs_bit_radix_cachep;
25 int set_radix_bit(struct radix_tree_root *radix, unsigned long bit)
26 {
27         unsigned long *bits;
28         unsigned long slot;
29         int bit_slot;
30         int ret;
31
32         slot = bit / BIT_RADIX_BITS_PER_ARRAY;
33         bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
34
35         bits = radix_tree_lookup(radix, slot);
36         if (!bits) {
37                 bits = kmem_cache_alloc(btrfs_bit_radix_cachep, GFP_NOFS);
38                 if (!bits)
39                         return -ENOMEM;
40                 memset(bits + 1, 0, BIT_ARRAY_BYTES - sizeof(unsigned long));
41                 bits[0] = slot;
42                 ret = radix_tree_insert(radix, slot, bits);
43                 if (ret)
44                         return ret;
45         }
46         ret = test_and_set_bit(bit_slot, bits + 1);
47         if (ret < 0)
48                 ret = 1;
49         return ret;
50 }
51
52 int test_radix_bit(struct radix_tree_root *radix, unsigned long bit)
53 {
54         unsigned long *bits;
55         unsigned long slot;
56         int bit_slot;
57
58         slot = bit / BIT_RADIX_BITS_PER_ARRAY;
59         bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
60
61         bits = radix_tree_lookup(radix, slot);
62         if (!bits)
63                 return 0;
64         return test_bit(bit_slot, bits + 1);
65 }
66
67 int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit)
68 {
69         unsigned long *bits;
70         unsigned long slot;
71         int bit_slot;
72         int i;
73         int empty = 1;
74
75         slot = bit / BIT_RADIX_BITS_PER_ARRAY;
76         bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
77
78         bits = radix_tree_lookup(radix, slot);
79         if (!bits)
80                 return 0;
81         clear_bit(bit_slot, bits + 1);
82         for (i = 1; i < BIT_ARRAY_BYTES / sizeof(unsigned long); i++) {
83                 if (bits[i]) {
84                         empty = 0;
85                         break;
86                 }
87         }
88         if (empty) {
89                 bits = radix_tree_delete(radix, slot);
90                 BUG_ON(!bits);
91                 kmem_cache_free(btrfs_bit_radix_cachep, bits);
92         }
93         return 0;
94 }
95
96 int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits,
97                          unsigned long start, int nr)
98 {
99         unsigned long *bits;
100         unsigned long *gang[4];
101         int found;
102         int ret;
103         int i;
104         int total_found = 0;
105         unsigned long slot;
106
107         slot = start / BIT_RADIX_BITS_PER_ARRAY;
108         ret = radix_tree_gang_lookup(radix, (void **)gang, slot,
109                                      ARRAY_SIZE(gang));
110         found = start % BIT_RADIX_BITS_PER_ARRAY;
111         for (i = 0; i < ret && nr > 0; i++) {
112                 bits = gang[i];
113                 while(nr > 0) {
114                         found = find_next_bit(bits + 1,
115                                               BIT_RADIX_BITS_PER_ARRAY,
116                                               found);
117                         if (found < BIT_RADIX_BITS_PER_ARRAY) {
118                                 *retbits = bits[0] *
119                                         BIT_RADIX_BITS_PER_ARRAY + found;
120                                 retbits++;
121                                 nr--;
122                                 total_found++;
123                                 found++;
124                         } else
125                                 break;
126                 }
127                 found = 0;
128         }
129         return total_found;
130 }