linux-stable/fs/hfsplus/part_tbl.c
Seth Forshee 6596528e39 hfsplus: ensure bio requests are not smaller than the hardware sectors
Currently all bio requests are 512 bytes, which may fail for media
whose physical sector size is larger than this. Ensure these
requests are not smaller than the block device logical block size.

BugLink: http://bugs.launchpad.net/bugs/734883
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
2011-07-22 16:37:44 +02:00

157 lines
4.2 KiB
C

/*
* linux/fs/hfsplus/part_tbl.c
*
* Copyright (C) 1996-1997 Paul H. Hargrove
* This file may be distributed under the terms of
* the GNU General Public License.
*
* Original code to handle the new style Mac partition table based on
* a patch contributed by Holger Schemel (aeglos@valinor.owl.de).
*
* In function preconditions the term "valid" applied to a pointer to
* a structure means that the pointer is non-NULL and the structure it
* points to has all fields initialized to consistent values.
*
*/
#include <linux/slab.h>
#include "hfsplus_fs.h"
/* offsets to various blocks */
#define HFS_DD_BLK 0 /* Driver Descriptor block */
#define HFS_PMAP_BLK 1 /* First block of partition map */
#define HFS_MDB_BLK 2 /* Block (w/i partition) of MDB */
/* magic numbers for various disk blocks */
#define HFS_DRVR_DESC_MAGIC 0x4552 /* "ER": driver descriptor map */
#define HFS_OLD_PMAP_MAGIC 0x5453 /* "TS": old-type partition map */
#define HFS_NEW_PMAP_MAGIC 0x504D /* "PM": new-type partition map */
#define HFS_SUPER_MAGIC 0x4244 /* "BD": HFS MDB (super block) */
#define HFS_MFS_SUPER_MAGIC 0xD2D7 /* MFS MDB (super block) */
/*
* The new style Mac partition map
*
* For each partition on the media there is a physical block (512-byte
* block) containing one of these structures. These blocks are
* contiguous starting at block 1.
*/
struct new_pmap {
__be16 pmSig; /* signature */
__be16 reSigPad; /* padding */
__be32 pmMapBlkCnt; /* partition blocks count */
__be32 pmPyPartStart; /* physical block start of partition */
__be32 pmPartBlkCnt; /* physical block count of partition */
u8 pmPartName[32]; /* (null terminated?) string
giving the name of this
partition */
u8 pmPartType[32]; /* (null terminated?) string
giving the type of this
partition */
/* a bunch more stuff we don't need */
} __packed;
/*
* The old style Mac partition map
*
* The partition map consists for a 2-byte signature followed by an
* array of these structures. The map is terminated with an all-zero
* one of these.
*/
struct old_pmap {
__be16 pdSig; /* Signature bytes */
struct old_pmap_entry {
__be32 pdStart;
__be32 pdSize;
__be32 pdFSID;
} pdEntry[42];
} __packed;
static int hfs_parse_old_pmap(struct super_block *sb, struct old_pmap *pm,
sector_t *part_start, sector_t *part_size)
{
struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
int i;
for (i = 0; i < 42; i++) {
struct old_pmap_entry *p = &pm->pdEntry[i];
if (p->pdStart && p->pdSize &&
p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ &&
(sbi->part < 0 || sbi->part == i)) {
*part_start += be32_to_cpu(p->pdStart);
*part_size = be32_to_cpu(p->pdSize);
return 0;
}
}
return -ENOENT;
}
static int hfs_parse_new_pmap(struct super_block *sb, void *buf,
struct new_pmap *pm, sector_t *part_start, sector_t *part_size)
{
struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
int size = be32_to_cpu(pm->pmMapBlkCnt);
int buf_size = hfsplus_min_io_size(sb);
int res;
int i = 0;
do {
if (!memcmp(pm->pmPartType, "Apple_HFS", 9) &&
(sbi->part < 0 || sbi->part == i)) {
*part_start += be32_to_cpu(pm->pmPyPartStart);
*part_size = be32_to_cpu(pm->pmPartBlkCnt);
return 0;
}
if (++i >= size)
return -ENOENT;
pm = (struct new_pmap *)((u8 *)pm + HFSPLUS_SECTOR_SIZE);
if ((u8 *)pm - (u8 *)buf >= buf_size) {
res = hfsplus_submit_bio(sb,
*part_start + HFS_PMAP_BLK + i,
buf, (void **)&pm, READ);
if (res)
return res;
}
} while (pm->pmSig == cpu_to_be16(HFS_NEW_PMAP_MAGIC));
return -ENOENT;
}
/*
* Parse the partition map looking for the start and length of a
* HFS/HFS+ partition.
*/
int hfs_part_find(struct super_block *sb,
sector_t *part_start, sector_t *part_size)
{
void *buf, *data;
int res;
buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
if (!buf)
return -ENOMEM;
res = hfsplus_submit_bio(sb, *part_start + HFS_PMAP_BLK,
buf, &data, READ);
if (res)
goto out;
switch (be16_to_cpu(*((__be16 *)data))) {
case HFS_OLD_PMAP_MAGIC:
res = hfs_parse_old_pmap(sb, data, part_start, part_size);
break;
case HFS_NEW_PMAP_MAGIC:
res = hfs_parse_new_pmap(sb, buf, data, part_start, part_size);
break;
default:
res = -ENOENT;
break;
}
out:
kfree(buf);
return res;
}