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fs/hfsplus/bitmap.c
4.79 KB
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/* * linux/fs/hfsplus/bitmap.c * * Copyright (C) 2001 * Brad Boyer (flar@allandria.com) * (C) 2003 Ardis Technologies <roman@ardistech.com> * * Handling of allocation file */ #include <linux/pagemap.h> #include "hfsplus_fs.h" #include "hfsplus_raw.h" #define PAGE_CACHE_BITS (PAGE_CACHE_SIZE * 8) |
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int hfsplus_block_allocate(struct super_block *sb, u32 size, u32 offset, u32 *max) |
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{ |
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struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); |
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struct page *page; struct address_space *mapping; __be32 *pptr, *curr, *end; u32 mask, start, len, n; __be32 val; int i; len = *max; if (!len) return size; dprint(DBG_BITMAP, "block_allocate: %u,%u,%u ", size, offset, len); |
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mutex_lock(&sbi->alloc_mutex); mapping = sbi->alloc_file->i_mapping; |
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page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL); |
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if (IS_ERR(page)) { start = size; goto out; } |
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pptr = kmap(page); curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32; i = offset % 32; offset &= ~(PAGE_CACHE_BITS - 1); if ((size ^ offset) / PAGE_CACHE_BITS) end = pptr + PAGE_CACHE_BITS / 32; else end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32; /* scan the first partial u32 for zero bits */ val = *curr; if (~val) { n = be32_to_cpu(val); mask = (1U << 31) >> i; for (; i < 32; mask >>= 1, i++) { if (!(n & mask)) goto found; } } curr++; /* scan complete u32s for the first zero bit */ while (1) { while (curr < end) { val = *curr; if (~val) { n = be32_to_cpu(val); mask = 1 << 31; for (i = 0; i < 32; mask >>= 1, i++) { if (!(n & mask)) goto found; } } curr++; } kunmap(page); offset += PAGE_CACHE_BITS; if (offset >= size) break; |
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page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL); |
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if (IS_ERR(page)) { start = size; goto out; } |
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curr = pptr = kmap(page); if ((size ^ offset) / PAGE_CACHE_BITS) end = pptr + PAGE_CACHE_BITS / 32; else end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32; } dprint(DBG_BITMAP, "bitmap full "); start = size; goto out; found: start = offset + (curr - pptr) * 32 + i; if (start >= size) { dprint(DBG_BITMAP, "bitmap full "); goto out; } /* do any partial u32 at the start */ len = min(size - start, len); while (1) { n |= mask; if (++i >= 32) break; mask >>= 1; if (!--len || n & mask) goto done; } if (!--len) goto done; *curr++ = cpu_to_be32(n); /* do full u32s */ while (1) { while (curr < end) { n = be32_to_cpu(*curr); if (len < 32) goto last; if (n) { len = 32; goto last; } *curr++ = cpu_to_be32(0xffffffff); len -= 32; } set_page_dirty(page); kunmap(page); offset += PAGE_CACHE_BITS; |
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page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL); |
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if (IS_ERR(page)) { start = size; goto out; } |
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pptr = kmap(page); curr = pptr; end = pptr + PAGE_CACHE_BITS / 32; } last: /* do any partial u32 at end */ mask = 1U << 31; for (i = 0; i < len; i++) { if (n & mask) break; n |= mask; mask >>= 1; } done: *curr = cpu_to_be32(n); set_page_dirty(page); kunmap(page); *max = offset + (curr - pptr) * 32 + i - start; |
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sbi->free_blocks -= *max; |
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sb->s_dirt = 1; dprint(DBG_BITMAP, "-> %u,%u ", start, *max); out: |
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mutex_unlock(&sbi->alloc_mutex); |
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return start; } int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count) { |
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struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb); |
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struct page *page; struct address_space *mapping; __be32 *pptr, *curr, *end; u32 mask, len, pnr; int i; /* is there any actual work to be done? */ if (!count) return 0; dprint(DBG_BITMAP, "block_free: %u,%u ", offset, count); /* are all of the bits in range? */ |
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if ((offset + count) > sbi->total_blocks) |
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return -2; |
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mutex_lock(&sbi->alloc_mutex); mapping = sbi->alloc_file->i_mapping; |
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pnr = offset / PAGE_CACHE_BITS; |
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page = read_mapping_page(mapping, pnr, NULL); |
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pptr = kmap(page); curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32; end = pptr + PAGE_CACHE_BITS / 32; len = count; /* do any partial u32 at the start */ i = offset % 32; if (i) { int j = 32 - i; mask = 0xffffffffU << j; if (j > count) { mask |= 0xffffffffU >> (i + count); *curr++ &= cpu_to_be32(mask); goto out; } *curr++ &= cpu_to_be32(mask); count -= j; } /* do full u32s */ while (1) { while (curr < end) { if (count < 32) goto done; *curr++ = 0; count -= 32; } if (!count) break; set_page_dirty(page); kunmap(page); |
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page = read_mapping_page(mapping, ++pnr, NULL); |
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pptr = kmap(page); curr = pptr; end = pptr + PAGE_CACHE_BITS / 32; } done: /* do any partial u32 at end */ if (count) { mask = 0xffffffffU >> count; *curr &= cpu_to_be32(mask); } out: set_page_dirty(page); kunmap(page); |
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sbi->free_blocks += len; |
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sb->s_dirt = 1; |
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mutex_unlock(&sbi->alloc_mutex); |
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return 0; } |