--- /dev/null
+/*
+ * 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)
+
+int hfsplus_block_allocate(struct super_block *sb, u32 size,
+ u32 offset, u32 *max)
+{
+ struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+ 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;
+
+ hfs_dbg(BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len);
+ mutex_lock(&sbi->alloc_mutex);
+ mapping = sbi->alloc_file->i_mapping;
+ page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL);
+ if (IS_ERR(page)) {
+ start = size;
+ goto out;
+ }
+ 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;
+ page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
+ NULL);
+ if (IS_ERR(page)) {
+ start = size;
+ goto out;
+ }
+ 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;
+ }
+ hfs_dbg(BITMAP, "bitmap full\n");
+ start = size;
+ goto out;
+
+found:
+ start = offset + (curr - pptr) * 32 + i;
+ if (start >= size) {
+ hfs_dbg(BITMAP, "bitmap full\n");
+ 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;
+ page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
+ NULL);
+ if (IS_ERR(page)) {
+ start = size;
+ goto out;
+ }
+ 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;
+ sbi->free_blocks -= *max;
+ hfsplus_mark_mdb_dirty(sb);
+ hfs_dbg(BITMAP, "-> %u,%u\n", start, *max);
+out:
+ mutex_unlock(&sbi->alloc_mutex);
+ return start;
+}
+
+int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
+{
+ struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+ 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;
+
+ hfs_dbg(BITMAP, "block_free: %u,%u\n", offset, count);
+ /* are all of the bits in range? */
+ if ((offset + count) > sbi->total_blocks)
+ return -ENOENT;
+
+ mutex_lock(&sbi->alloc_mutex);
+ mapping = sbi->alloc_file->i_mapping;
+ pnr = offset / PAGE_CACHE_BITS;
+ page = read_mapping_page(mapping, pnr, NULL);
+ if (IS_ERR(page))
+ goto kaboom;
+ 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);
+ page = read_mapping_page(mapping, ++pnr, NULL);
+ if (IS_ERR(page))
+ goto kaboom;
+ 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);
+ sbi->free_blocks += len;
+ hfsplus_mark_mdb_dirty(sb);
+ mutex_unlock(&sbi->alloc_mutex);
+
+ return 0;
+
+kaboom:
+ pr_crit("unable to mark blocks free: error %ld\n", PTR_ERR(page));
+ mutex_unlock(&sbi->alloc_mutex);
+
+ return -EIO;
+}
Code Review / kvmfornfv.git / blobdiff