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