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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * This tries to keep block devices away from devfs as much as possible. | |
3 | */ | |
4 | #include <linux/fs.h> | |
5 | #include <linux/devfs_fs_kernel.h> | |
6 | #include <linux/vmalloc.h> | |
7 | #include <linux/genhd.h> | |
8 | #include <linux/bitops.h> | |
353ab6e9 | 9 | #include <linux/mutex.h> |
1da177e4 LT |
10 | |
11 | ||
12 | struct unique_numspace { | |
13 | u32 num_free; /* Num free in bits */ | |
14 | u32 length; /* Array length in bytes */ | |
15 | unsigned long *bits; | |
16 | struct semaphore mutex; | |
17 | }; | |
18 | ||
353ab6e9 | 19 | static DEFINE_MUTEX(numspace_mutex); |
1da177e4 LT |
20 | |
21 | static int expand_numspace(struct unique_numspace *s) | |
22 | { | |
23 | u32 length; | |
24 | void *bits; | |
25 | ||
26 | if (s->length < 16) | |
27 | length = 16; | |
28 | else | |
29 | length = s->length << 1; | |
30 | ||
31 | bits = vmalloc(length); | |
32 | if (!bits) | |
33 | return -ENOMEM; | |
34 | if (s->bits) { | |
35 | memcpy(bits, s->bits, s->length); | |
36 | vfree(s->bits); | |
37 | } | |
38 | ||
39 | s->num_free = (length - s->length) << 3; | |
40 | s->bits = bits; | |
41 | memset(bits + s->length, 0, length - s->length); | |
42 | s->length = length; | |
43 | ||
44 | return 0; | |
45 | } | |
46 | ||
47 | static int alloc_unique_number(struct unique_numspace *s) | |
48 | { | |
49 | int rval = 0; | |
50 | ||
353ab6e9 | 51 | mutex_lock(&numspace_mutex); |
1da177e4 LT |
52 | if (s->num_free < 1) |
53 | rval = expand_numspace(s); | |
54 | if (!rval) { | |
55 | rval = find_first_zero_bit(s->bits, s->length << 3); | |
56 | --s->num_free; | |
57 | __set_bit(rval, s->bits); | |
58 | } | |
353ab6e9 | 59 | mutex_unlock(&numspace_mutex); |
1da177e4 LT |
60 | |
61 | return rval; | |
62 | } | |
63 | ||
64 | static void dealloc_unique_number(struct unique_numspace *s, int number) | |
65 | { | |
66 | int old_val; | |
67 | ||
68 | if (number >= 0) { | |
353ab6e9 | 69 | mutex_lock(&numspace_mutex); |
1da177e4 LT |
70 | old_val = __test_and_clear_bit(number, s->bits); |
71 | if (old_val) | |
72 | ++s->num_free; | |
353ab6e9 | 73 | mutex_unlock(&numspace_mutex); |
1da177e4 LT |
74 | } |
75 | } | |
76 | ||
77 | static struct unique_numspace disc_numspace; | |
78 | static struct unique_numspace cdrom_numspace; | |
79 | ||
80 | void devfs_add_partitioned(struct gendisk *disk) | |
81 | { | |
82 | char dirname[64], symlink[16]; | |
83 | ||
84 | devfs_mk_dir(disk->devfs_name); | |
85 | devfs_mk_bdev(MKDEV(disk->major, disk->first_minor), | |
86 | S_IFBLK|S_IRUSR|S_IWUSR, | |
87 | "%s/disc", disk->devfs_name); | |
88 | ||
89 | disk->number = alloc_unique_number(&disc_numspace); | |
90 | ||
91 | sprintf(symlink, "discs/disc%d", disk->number); | |
92 | sprintf(dirname, "../%s", disk->devfs_name); | |
93 | devfs_mk_symlink(symlink, dirname); | |
94 | ||
95 | } | |
96 | ||
97 | void devfs_add_disk(struct gendisk *disk) | |
98 | { | |
99 | devfs_mk_bdev(MKDEV(disk->major, disk->first_minor), | |
100 | (disk->flags & GENHD_FL_CD) ? | |
101 | S_IFBLK|S_IRUGO|S_IWUGO : | |
102 | S_IFBLK|S_IRUSR|S_IWUSR, | |
103 | "%s", disk->devfs_name); | |
104 | ||
105 | if (disk->flags & GENHD_FL_CD) { | |
106 | char dirname[64], symlink[16]; | |
107 | ||
108 | disk->number = alloc_unique_number(&cdrom_numspace); | |
109 | ||
110 | sprintf(symlink, "cdroms/cdrom%d", disk->number); | |
111 | sprintf(dirname, "../%s", disk->devfs_name); | |
112 | devfs_mk_symlink(symlink, dirname); | |
113 | } | |
114 | } | |
115 | ||
116 | void devfs_remove_disk(struct gendisk *disk) | |
117 | { | |
118 | if (disk->minors != 1) { | |
119 | devfs_remove("discs/disc%d", disk->number); | |
120 | dealloc_unique_number(&disc_numspace, disk->number); | |
121 | devfs_remove("%s/disc", disk->devfs_name); | |
122 | } | |
123 | if (disk->flags & GENHD_FL_CD) { | |
124 | devfs_remove("cdroms/cdrom%d", disk->number); | |
125 | dealloc_unique_number(&cdrom_numspace, disk->number); | |
126 | } | |
127 | devfs_remove(disk->devfs_name); | |
128 | } | |
129 | ||
130 |