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