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![Eric Sesterhenn](/assets/img/avatar_default.png)
While testing more corrupted images with hfsplus, i came across one which triggered the following bug: [15840.675016] BUG: unable to handle kernel paging request at fffffffb [15840.675016] IP: [<c0116a4f>] kmap+0x15/0x56 [15840.675016] *pde = 00008067 *pte = 00000000 [15840.675016] Oops: 0000 [#1] PREEMPT DEBUG_PAGEALLOC [15840.675016] Modules linked in: [15840.675016] [15840.675016] Pid: 11575, comm: ln Not tainted (2.6.27-rc4-00123-gd3ee1b4-dirty #29) [15840.675016] EIP: 0060:[<c0116a4f>] EFLAGS: 00010202 CPU: 0 [15840.675016] EIP is at kmap+0x15/0x56 [15840.675016] EAX: 00000246 EBX: fffffffb ECX: 00000000 EDX: cab919c0 [15840.675016] ESI: 000007dd EDI: cab0bcf4 EBP: cab0bc98 ESP: cab0bc94 [15840.675016] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068 [15840.675016] Process ln (pid: 11575, ti=cab0b000 task=cab919c0 task.ti=cab0b000) [15840.675016] Stack: 00000000 cab0bcdc c0231cfb 00000000 cab0bce0 00000800 ca9290c0 fffffffb [15840.675016] cab145d0 cab919c0 cab15998 22222222 22222222 22222222 00000001 cab15960 [15840.675016] 000007dd cab0bcf4 cab0bd04 c022cb3a cab0bcf4 cab15a6c ca9290c0 00000000 [15840.675016] Call Trace: [15840.675016] [<c0231cfb>] ? hfsplus_block_allocate+0x6f/0x2d3 [15840.675016] [<c022cb3a>] ? hfsplus_file_extend+0xc4/0x1db [15840.675016] [<c022ce41>] ? hfsplus_get_block+0x8c/0x19d [15840.675016] [<c06adde4>] ? sub_preempt_count+0x9d/0xab [15840.675016] [<c019ece6>] ? __block_prepare_write+0x147/0x311 [15840.675016] [<c0161934>] ? __grab_cache_page+0x52/0x73 [15840.675016] [<c019ef4f>] ? block_write_begin+0x79/0xd5 [15840.675016] [<c022cdb5>] ? hfsplus_get_block+0x0/0x19d [15840.675016] [<c019f22a>] ? cont_write_begin+0x27f/0x2af [15840.675016] [<c022cdb5>] ? hfsplus_get_block+0x0/0x19d [15840.675016] [<c0139ebe>] ? tick_program_event+0x28/0x4c [15840.675016] [<c013bd35>] ? trace_hardirqs_off+0xb/0xd [15840.675016] [<c022b723>] ? hfsplus_write_begin+0x2d/0x32 [15840.675016] [<c022cdb5>] ? hfsplus_get_block+0x0/0x19d [15840.675016] [<c0161988>] ? pagecache_write_begin+0x33/0x107 [15840.675016] [<c01879e5>] ? __page_symlink+0x3c/0xae [15840.675016] [<c019ad34>] ? __mark_inode_dirty+0x12f/0x137 [15840.675016] [<c0187a70>] ? page_symlink+0x19/0x1e [15840.675016] [<c022e6eb>] ? hfsplus_symlink+0x41/0xa6 [15840.675016] [<c01886a9>] ? vfs_symlink+0x99/0x101 [15840.675016] [<c018a2f6>] ? sys_symlinkat+0x6b/0xad [15840.675016] [<c018a348>] ? sys_symlink+0x10/0x12 [15840.675016] [<c01038bd>] ? sysenter_do_call+0x12/0x31 [15840.675016] ======================= [15840.675016] Code: 00 00 75 10 83 3d 88 2f ec c0 02 75 07 89 d0 e8 12 56 05 00 5d c3 55 ba 06 00 00 00 89 e5 53 89 c3 b8 3d eb 7e c0 e8 16 74 00 00 <8b> 03 c1 e8 1e 69 c0 d8 02 00 00 05 b8 69 8e c0 2b 80 c4 02 00 [15840.675016] EIP: [<c0116a4f>] kmap+0x15/0x56 SS:ESP 0068:cab0bc94 [15840.675016] ---[ end trace 4fea40dad6b70e5f ]--- This happens because the return value of read_mapping_page() is passed on to kmap unchecked. The bug is triggered after the first read_mapping_page() in hfsplus_block_allocate(), this patch fixes all three usages in this functions but leaves the ones further down in the file unchanged. Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de> Cc: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
232 lines
4.8 KiB
C
232 lines
4.8 KiB
C
/*
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* linux/fs/hfsplus/bitmap.c
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*
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* Copyright (C) 2001
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* Brad Boyer (flar@allandria.com)
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* (C) 2003 Ardis Technologies <roman@ardistech.com>
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*
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* Handling of allocation file
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*/
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#include <linux/pagemap.h>
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#include "hfsplus_fs.h"
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#include "hfsplus_raw.h"
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#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 page *page;
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struct address_space *mapping;
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__be32 *pptr, *curr, *end;
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u32 mask, start, len, n;
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__be32 val;
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int i;
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len = *max;
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if (!len)
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return size;
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dprint(DBG_BITMAP, "block_allocate: %u,%u,%u\n", size, offset, len);
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mutex_lock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
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mapping = HFSPLUS_SB(sb).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)) {
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start = size;
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goto out;
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}
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pptr = kmap(page);
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curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
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i = offset % 32;
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offset &= ~(PAGE_CACHE_BITS - 1);
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if ((size ^ offset) / PAGE_CACHE_BITS)
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end = pptr + PAGE_CACHE_BITS / 32;
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else
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end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
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/* scan the first partial u32 for zero bits */
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val = *curr;
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if (~val) {
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n = be32_to_cpu(val);
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mask = (1U << 31) >> i;
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for (; i < 32; mask >>= 1, i++) {
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if (!(n & mask))
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goto found;
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}
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}
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curr++;
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/* scan complete u32s for the first zero bit */
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while (1) {
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while (curr < end) {
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val = *curr;
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if (~val) {
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n = be32_to_cpu(val);
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mask = 1 << 31;
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for (i = 0; i < 32; mask >>= 1, i++) {
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if (!(n & mask))
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goto found;
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}
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}
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curr++;
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}
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kunmap(page);
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offset += PAGE_CACHE_BITS;
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if (offset >= size)
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break;
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page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
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NULL);
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if (IS_ERR(page)) {
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start = size;
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goto out;
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}
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curr = pptr = kmap(page);
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if ((size ^ offset) / PAGE_CACHE_BITS)
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end = pptr + PAGE_CACHE_BITS / 32;
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else
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end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
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}
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dprint(DBG_BITMAP, "bitmap full\n");
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start = size;
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goto out;
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found:
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start = offset + (curr - pptr) * 32 + i;
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if (start >= size) {
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dprint(DBG_BITMAP, "bitmap full\n");
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goto out;
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}
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/* do any partial u32 at the start */
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len = min(size - start, len);
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while (1) {
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n |= mask;
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if (++i >= 32)
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break;
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mask >>= 1;
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if (!--len || n & mask)
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goto done;
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}
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if (!--len)
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goto done;
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*curr++ = cpu_to_be32(n);
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/* do full u32s */
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while (1) {
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while (curr < end) {
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n = be32_to_cpu(*curr);
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if (len < 32)
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goto last;
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if (n) {
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len = 32;
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goto last;
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}
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*curr++ = cpu_to_be32(0xffffffff);
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len -= 32;
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}
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set_page_dirty(page);
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kunmap(page);
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offset += PAGE_CACHE_BITS;
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page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
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NULL);
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if (IS_ERR(page)) {
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start = size;
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goto out;
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}
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pptr = kmap(page);
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curr = pptr;
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end = pptr + PAGE_CACHE_BITS / 32;
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}
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last:
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/* do any partial u32 at end */
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mask = 1U << 31;
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for (i = 0; i < len; i++) {
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if (n & mask)
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break;
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n |= mask;
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mask >>= 1;
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}
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done:
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*curr = cpu_to_be32(n);
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set_page_dirty(page);
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kunmap(page);
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*max = offset + (curr - pptr) * 32 + i - start;
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HFSPLUS_SB(sb).free_blocks -= *max;
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sb->s_dirt = 1;
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dprint(DBG_BITMAP, "-> %u,%u\n", start, *max);
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out:
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mutex_unlock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
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return start;
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}
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int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
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{
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struct page *page;
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struct address_space *mapping;
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__be32 *pptr, *curr, *end;
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u32 mask, len, pnr;
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int i;
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/* is there any actual work to be done? */
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if (!count)
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return 0;
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dprint(DBG_BITMAP, "block_free: %u,%u\n", offset, count);
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/* are all of the bits in range? */
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if ((offset + count) > HFSPLUS_SB(sb).total_blocks)
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return -2;
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mutex_lock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
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mapping = HFSPLUS_SB(sb).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);
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curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
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end = pptr + PAGE_CACHE_BITS / 32;
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len = count;
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/* do any partial u32 at the start */
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i = offset % 32;
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if (i) {
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int j = 32 - i;
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mask = 0xffffffffU << j;
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if (j > count) {
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mask |= 0xffffffffU >> (i + count);
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*curr++ &= cpu_to_be32(mask);
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goto out;
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}
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*curr++ &= cpu_to_be32(mask);
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count -= j;
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}
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/* do full u32s */
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while (1) {
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while (curr < end) {
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if (count < 32)
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goto done;
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*curr++ = 0;
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count -= 32;
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}
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if (!count)
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break;
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set_page_dirty(page);
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kunmap(page);
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page = read_mapping_page(mapping, ++pnr, NULL);
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pptr = kmap(page);
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curr = pptr;
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end = pptr + PAGE_CACHE_BITS / 32;
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}
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done:
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/* do any partial u32 at end */
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if (count) {
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mask = 0xffffffffU >> count;
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*curr &= cpu_to_be32(mask);
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}
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out:
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set_page_dirty(page);
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kunmap(page);
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HFSPLUS_SB(sb).free_blocks += len;
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sb->s_dirt = 1;
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mutex_unlock(&HFSPLUS_SB(sb).alloc_file->i_mutex);
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return 0;
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}
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