mirror of https://gitee.com/openkylin/linux.git
131 lines
3.1 KiB
C
131 lines
3.1 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include "bit-radix.h"
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#define BIT_ARRAY_BYTES 256
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#define BIT_RADIX_BITS_PER_ARRAY ((BIT_ARRAY_BYTES - sizeof(unsigned long)) * 8)
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extern struct kmem_cache *btrfs_bit_radix_cachep;
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int set_radix_bit(struct radix_tree_root *radix, unsigned long bit)
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{
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unsigned long *bits;
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unsigned long slot;
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int bit_slot;
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int ret;
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slot = bit / BIT_RADIX_BITS_PER_ARRAY;
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bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
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bits = radix_tree_lookup(radix, slot);
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if (!bits) {
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bits = kmem_cache_alloc(btrfs_bit_radix_cachep, GFP_NOFS);
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if (!bits)
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return -ENOMEM;
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memset(bits + 1, 0, BIT_ARRAY_BYTES - sizeof(unsigned long));
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bits[0] = slot;
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ret = radix_tree_insert(radix, slot, bits);
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if (ret)
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return ret;
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}
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ret = test_and_set_bit(bit_slot, bits + 1);
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if (ret < 0)
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ret = 1;
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return ret;
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}
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int test_radix_bit(struct radix_tree_root *radix, unsigned long bit)
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{
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unsigned long *bits;
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unsigned long slot;
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int bit_slot;
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slot = bit / BIT_RADIX_BITS_PER_ARRAY;
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bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
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bits = radix_tree_lookup(radix, slot);
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if (!bits)
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return 0;
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return test_bit(bit_slot, bits + 1);
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}
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int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit)
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{
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unsigned long *bits;
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unsigned long slot;
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int bit_slot;
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int i;
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int empty = 1;
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slot = bit / BIT_RADIX_BITS_PER_ARRAY;
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bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY;
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bits = radix_tree_lookup(radix, slot);
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if (!bits)
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return 0;
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clear_bit(bit_slot, bits + 1);
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for (i = 1; i < BIT_ARRAY_BYTES / sizeof(unsigned long); i++) {
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if (bits[i]) {
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empty = 0;
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break;
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}
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}
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if (empty) {
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bits = radix_tree_delete(radix, slot);
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BUG_ON(!bits);
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kmem_cache_free(btrfs_bit_radix_cachep, bits);
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}
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return 0;
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}
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int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits,
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unsigned long start, int nr)
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{
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unsigned long *bits;
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unsigned long *gang[4];
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int found;
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int ret;
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int i;
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int total_found = 0;
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unsigned long slot;
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slot = start / BIT_RADIX_BITS_PER_ARRAY;
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ret = radix_tree_gang_lookup(radix, (void **)gang, slot,
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ARRAY_SIZE(gang));
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found = start % BIT_RADIX_BITS_PER_ARRAY;
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for (i = 0; i < ret && nr > 0; i++) {
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bits = gang[i];
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while(nr > 0) {
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found = find_next_bit(bits + 1,
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BIT_RADIX_BITS_PER_ARRAY,
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found);
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if (found < BIT_RADIX_BITS_PER_ARRAY) {
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*retbits = bits[0] *
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BIT_RADIX_BITS_PER_ARRAY + found;
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retbits++;
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nr--;
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total_found++;
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found++;
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} else
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break;
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}
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found = 0;
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}
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return total_found;
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}
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