1 | // SPDX-License-Identifier: GPL-2.0 |
2 | #include <linux/kernel.h> |
3 | #include <linux/fs.h> |
4 | #include <linux/buffer_head.h> |
5 | #include <asm/div64.h> |
6 | #include "omfs.h" |
7 | |
8 | unsigned long omfs_count_free(struct super_block *sb) |
9 | { |
10 | unsigned int i; |
11 | unsigned long sum = 0; |
12 | struct omfs_sb_info *sbi = OMFS_SB(sb); |
13 | int nbits = sb->s_blocksize * 8; |
14 | |
15 | for (i = 0; i < sbi->s_imap_size; i++) |
16 | sum += nbits - bitmap_weight(src: sbi->s_imap[i], nbits); |
17 | |
18 | return sum; |
19 | } |
20 | |
21 | /* |
22 | * Counts the run of zero bits starting at bit up to max. |
23 | * It handles the case where a run might spill over a buffer. |
24 | * Called with bitmap lock. |
25 | */ |
26 | static int count_run(unsigned long **addr, int nbits, |
27 | int addrlen, int bit, int max) |
28 | { |
29 | int count = 0; |
30 | int x; |
31 | |
32 | for (; addrlen > 0; addrlen--, addr++) { |
33 | x = find_next_bit(addr: *addr, size: nbits, offset: bit); |
34 | count += x - bit; |
35 | |
36 | if (x < nbits || count > max) |
37 | return min(count, max); |
38 | |
39 | bit = 0; |
40 | } |
41 | return min(count, max); |
42 | } |
43 | |
44 | /* |
45 | * Sets or clears the run of count bits starting with bit. |
46 | * Called with bitmap lock. |
47 | */ |
48 | static int set_run(struct super_block *sb, int map, |
49 | int nbits, int bit, int count, int set) |
50 | { |
51 | int i; |
52 | int err; |
53 | struct buffer_head *bh; |
54 | struct omfs_sb_info *sbi = OMFS_SB(sb); |
55 | |
56 | err = -ENOMEM; |
57 | bh = sb_bread(sb, block: clus_to_blk(sbi, block: sbi->s_bitmap_ino) + map); |
58 | if (!bh) |
59 | goto out; |
60 | |
61 | for (i = 0; i < count; i++, bit++) { |
62 | if (bit >= nbits) { |
63 | bit = 0; |
64 | map++; |
65 | |
66 | mark_buffer_dirty(bh); |
67 | brelse(bh); |
68 | bh = sb_bread(sb, |
69 | block: clus_to_blk(sbi, block: sbi->s_bitmap_ino) + map); |
70 | if (!bh) |
71 | goto out; |
72 | } |
73 | if (set) { |
74 | set_bit(nr: bit, addr: sbi->s_imap[map]); |
75 | set_bit(nr: bit, addr: (unsigned long *)bh->b_data); |
76 | } else { |
77 | clear_bit(nr: bit, addr: sbi->s_imap[map]); |
78 | clear_bit(nr: bit, addr: (unsigned long *)bh->b_data); |
79 | } |
80 | } |
81 | mark_buffer_dirty(bh); |
82 | brelse(bh); |
83 | err = 0; |
84 | out: |
85 | return err; |
86 | } |
87 | |
88 | /* |
89 | * Tries to allocate exactly one block. Returns true if successful. |
90 | */ |
91 | int omfs_allocate_block(struct super_block *sb, u64 block) |
92 | { |
93 | struct buffer_head *bh; |
94 | struct omfs_sb_info *sbi = OMFS_SB(sb); |
95 | int bits_per_entry = 8 * sb->s_blocksize; |
96 | unsigned int map, bit; |
97 | int ret = 0; |
98 | u64 tmp; |
99 | |
100 | tmp = block; |
101 | bit = do_div(tmp, bits_per_entry); |
102 | map = tmp; |
103 | |
104 | mutex_lock(&sbi->s_bitmap_lock); |
105 | if (map >= sbi->s_imap_size || test_and_set_bit(nr: bit, addr: sbi->s_imap[map])) |
106 | goto out; |
107 | |
108 | if (sbi->s_bitmap_ino > 0) { |
109 | bh = sb_bread(sb, block: clus_to_blk(sbi, block: sbi->s_bitmap_ino) + map); |
110 | if (!bh) |
111 | goto out; |
112 | |
113 | set_bit(nr: bit, addr: (unsigned long *)bh->b_data); |
114 | mark_buffer_dirty(bh); |
115 | brelse(bh); |
116 | } |
117 | ret = 1; |
118 | out: |
119 | mutex_unlock(lock: &sbi->s_bitmap_lock); |
120 | return ret; |
121 | } |
122 | |
123 | |
124 | /* |
125 | * Tries to allocate a set of blocks. The request size depends on the |
126 | * type: for inodes, we must allocate sbi->s_mirrors blocks, and for file |
127 | * blocks, we try to allocate sbi->s_clustersize, but can always get away |
128 | * with just one block. |
129 | */ |
130 | int omfs_allocate_range(struct super_block *sb, |
131 | int min_request, |
132 | int max_request, |
133 | u64 *return_block, |
134 | int *return_size) |
135 | { |
136 | struct omfs_sb_info *sbi = OMFS_SB(sb); |
137 | int bits_per_entry = 8 * sb->s_blocksize; |
138 | int ret = 0; |
139 | int i, run, bit; |
140 | |
141 | mutex_lock(&sbi->s_bitmap_lock); |
142 | for (i = 0; i < sbi->s_imap_size; i++) { |
143 | bit = 0; |
144 | while (bit < bits_per_entry) { |
145 | bit = find_next_zero_bit(addr: sbi->s_imap[i], size: bits_per_entry, |
146 | offset: bit); |
147 | |
148 | if (bit == bits_per_entry) |
149 | break; |
150 | |
151 | run = count_run(addr: &sbi->s_imap[i], nbits: bits_per_entry, |
152 | addrlen: sbi->s_imap_size-i, bit, max: max_request); |
153 | |
154 | if (run >= min_request) |
155 | goto found; |
156 | bit += run; |
157 | } |
158 | } |
159 | ret = -ENOSPC; |
160 | goto out; |
161 | |
162 | found: |
163 | *return_block = (u64) i * bits_per_entry + bit; |
164 | *return_size = run; |
165 | ret = set_run(sb, map: i, nbits: bits_per_entry, bit, count: run, set: 1); |
166 | |
167 | out: |
168 | mutex_unlock(lock: &sbi->s_bitmap_lock); |
169 | return ret; |
170 | } |
171 | |
172 | /* |
173 | * Clears count bits starting at a given block. |
174 | */ |
175 | int omfs_clear_range(struct super_block *sb, u64 block, int count) |
176 | { |
177 | struct omfs_sb_info *sbi = OMFS_SB(sb); |
178 | int bits_per_entry = 8 * sb->s_blocksize; |
179 | u64 tmp; |
180 | unsigned int map, bit; |
181 | int ret; |
182 | |
183 | tmp = block; |
184 | bit = do_div(tmp, bits_per_entry); |
185 | map = tmp; |
186 | |
187 | if (map >= sbi->s_imap_size) |
188 | return 0; |
189 | |
190 | mutex_lock(&sbi->s_bitmap_lock); |
191 | ret = set_run(sb, map, nbits: bits_per_entry, bit, count, set: 0); |
192 | mutex_unlock(lock: &sbi->s_bitmap_lock); |
193 | return ret; |
194 | } |
195 | |