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Message-ID: <876358iehd.fsf@devron.myhome.or.jp>
Date: Sun, 07 Mar 2010 19:59:58 +0900
From: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Daniel Taylor" <Daniel.Taylor@....com>,
<linux-kernel@...r.kernel.org>, "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] msdos: add support for large disks
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp> writes:
> BTW, to make sure, this is fs/partitions/, not fs/fat/. So, I'm not
> sure, my knowledge is enough or not, and/or you just missed
> fs/partitions/.
>
> Well, I'll make time to check. BTW, basically it sounds good to me
> except implementation details. But, I'd like to compare and check other
> implement a bit if possible. IIRC, this is not a well defined
> specification.
I reviewed/tested more or less on [RESUBMIT PATCH] patch. And rediff
with fixed patch is attached.
> Signed-off-by: Daniel Taylor <daniel.taylor@....com> diff --git
> a/fs/partitions/msdos.c b/fs/partitions/msdos.c index 0028d2e..039bb61
> 100644
This patch is broken like this way. I couldn't apply this, so I applied
by hand this time though, it can be easily to miss. Please fix your
mailer (or if not possible to fix, attach is better off than broken, at
least for me).
> @@ -348,7 +355,8 @@ parse_unixware(struct parsed_partitions *state, struct
> block_device *bdev,
>
> if (p->s_label != UNIXWARE_FS_UNUSED)
> put_partition(state, state->next++,
> - START_SECT(p), NR_SECTS(p));
> + start_sect((struct partition *)p),
> + nr_sects((struct partition *)p));
This is a wrong conversion for macro to function. "p" is not "struct
partition" in here. And it seems we have no reason to use
get_unaligned() for this, so just use le32_to_cpu() instead.
And related to > 1024b sector (this is not new for this patch though),
/* prevent someone doing mkfs or mkswap on an
extended partition, but leave room for LILO */
put_partition(state, slot, start, size == 1 ? 1 : 2);
This part is broken. If "size" is smaller than minimum blocksize (note,
"size" is number of 512b, not number of blocksize), we can't read any
block after all (it is handled as outside of i_size by bdev).
Peter (or someone) know what do we want to in here? This is on extended
partition itself (e.g. if sda1 sda2 <sda5 sda6>, it's the size of sda2)
[BTW, it seems subtypes stuff is not thinking about sector size > 512b...]
Thanks.
--
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
From: "Daniel Taylor" <Daniel.Taylor@....com>
In order to use disks larger than 2TiB on Windows XP, it is necessary
to use 4096-byte logical sectors in an MBR.
Although the kernel storage and functions called from msdos.c used
"sector_t" internally, msdos.c still used u32 variables, which results
in the ability to handle XP-compatible large disks.
This patch changes the internal variables to "sector_t".
Signed-off-by: Daniel Taylor <daniel.taylor@....com>
[tweaks and fix]
Signed-off-by: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
---
fs/partitions/msdos.c | 74 +++++++++++++++++++++++++------------------------
1 file changed, 39 insertions(+), 35 deletions(-)
diff -puN fs/partitions/msdos.c~part-support-4k-block fs/partitions/msdos.c
--- linux-2.6/fs/partitions/msdos.c~part-support-4k-block 2010-03-07 04:10:48.000000000 +0900
+++ linux-2.6-hirofumi/fs/partitions/msdos.c 2010-03-07 19:41:56.000000000 +0900
@@ -31,14 +31,17 @@
*/
#include <asm/unaligned.h>
-#define SYS_IND(p) (get_unaligned(&p->sys_ind))
-#define NR_SECTS(p) ({ __le32 __a = get_unaligned(&p->nr_sects); \
- le32_to_cpu(__a); \
- })
-
-#define START_SECT(p) ({ __le32 __a = get_unaligned(&p->start_sect); \
- le32_to_cpu(__a); \
- })
+#define SYS_IND(p) get_unaligned(&p->sys_ind)
+
+static inline sector_t nr_sects(struct partition *p)
+{
+ return (sector_t)get_unaligned_le32(&p->nr_sects);
+}
+
+static inline sector_t start_sect(struct partition *p)
+{
+ return (sector_t)get_unaligned_le32(&p->start_sect);
+}
static inline int is_extended_partition(struct partition *p)
{
@@ -104,13 +107,13 @@ static int aix_magic_present(unsigned ch
static void
parse_extended(struct parsed_partitions *state, struct block_device *bdev,
- u32 first_sector, u32 first_size)
+ sector_t first_sector, sector_t first_size)
{
struct partition *p;
Sector sect;
unsigned char *data;
- u32 this_sector, this_size;
- int sector_size = bdev_logical_block_size(bdev) / 512;
+ sector_t this_sector, this_size;
+ sector_t sector_size = bdev_logical_block_size(bdev) / 512;
int loopct = 0; /* number of links followed
without finding a data partition */
int i;
@@ -145,14 +148,14 @@ parse_extended(struct parsed_partitions
* First process the data partition(s)
*/
for (i=0; i<4; i++, p++) {
- u32 offs, size, next;
- if (!NR_SECTS(p) || is_extended_partition(p))
+ sector_t offs, size, next;
+ if (!nr_sects(p) || is_extended_partition(p))
continue;
/* Check the 3rd and 4th entries -
these sometimes contain random garbage */
- offs = START_SECT(p)*sector_size;
- size = NR_SECTS(p)*sector_size;
+ offs = start_sect(p)*sector_size;
+ size = nr_sects(p)*sector_size;
next = this_sector + offs;
if (i >= 2) {
if (offs + size > this_size)
@@ -179,13 +182,13 @@ parse_extended(struct parsed_partitions
*/
p -= 4;
for (i=0; i<4; i++, p++)
- if (NR_SECTS(p) && is_extended_partition(p))
+ if (nr_sects(p) && is_extended_partition(p))
break;
if (i == 4)
goto done; /* nothing left to do */
- this_sector = first_sector + START_SECT(p) * sector_size;
- this_size = NR_SECTS(p) * sector_size;
+ this_sector = first_sector + start_sect(p) * sector_size;
+ this_size = nr_sects(p) * sector_size;
put_dev_sector(sect);
}
done:
@@ -197,7 +200,7 @@ done:
static void
parse_solaris_x86(struct parsed_partitions *state, struct block_device *bdev,
- u32 offset, u32 size, int origin)
+ sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_SOLARIS_X86_PARTITION
Sector sect;
@@ -244,7 +247,7 @@ parse_solaris_x86(struct parsed_partitio
*/
static void
parse_bsd(struct parsed_partitions *state, struct block_device *bdev,
- u32 offset, u32 size, int origin, char *flavour,
+ sector_t offset, sector_t size, int origin, char *flavour,
int max_partitions)
{
Sector sect;
@@ -263,7 +266,7 @@ parse_bsd(struct parsed_partitions *stat
if (le16_to_cpu(l->d_npartitions) < max_partitions)
max_partitions = le16_to_cpu(l->d_npartitions);
for (p = l->d_partitions; p - l->d_partitions < max_partitions; p++) {
- u32 bsd_start, bsd_size;
+ sector_t bsd_start, bsd_size;
if (state->next == state->limit)
break;
@@ -290,7 +293,7 @@ parse_bsd(struct parsed_partitions *stat
static void
parse_freebsd(struct parsed_partitions *state, struct block_device *bdev,
- u32 offset, u32 size, int origin)
+ sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_BSD_DISKLABEL
parse_bsd(state, bdev, offset, size, origin,
@@ -300,7 +303,7 @@ parse_freebsd(struct parsed_partitions *
static void
parse_netbsd(struct parsed_partitions *state, struct block_device *bdev,
- u32 offset, u32 size, int origin)
+ sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_BSD_DISKLABEL
parse_bsd(state, bdev, offset, size, origin,
@@ -310,7 +313,7 @@ parse_netbsd(struct parsed_partitions *s
static void
parse_openbsd(struct parsed_partitions *state, struct block_device *bdev,
- u32 offset, u32 size, int origin)
+ sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_BSD_DISKLABEL
parse_bsd(state, bdev, offset, size, origin,
@@ -324,7 +327,7 @@ parse_openbsd(struct parsed_partitions *
*/
static void
parse_unixware(struct parsed_partitions *state, struct block_device *bdev,
- u32 offset, u32 size, int origin)
+ sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_UNIXWARE_DISKLABEL
Sector sect;
@@ -348,7 +351,8 @@ parse_unixware(struct parsed_partitions
if (p->s_label != UNIXWARE_FS_UNUSED)
put_partition(state, state->next++,
- START_SECT(p), NR_SECTS(p));
+ le32_to_cpu(p->start_sect),
+ le32_to_cpu(p->nr_sects));
p++;
}
put_dev_sector(sect);
@@ -363,7 +367,7 @@ parse_unixware(struct parsed_partitions
*/
static void
parse_minix(struct parsed_partitions *state, struct block_device *bdev,
- u32 offset, u32 size, int origin)
+ sector_t offset, sector_t size, int origin)
{
#ifdef CONFIG_MINIX_SUBPARTITION
Sector sect;
@@ -390,7 +394,7 @@ parse_minix(struct parsed_partitions *st
/* add each partition in use */
if (SYS_IND(p) == MINIX_PARTITION)
put_partition(state, state->next++,
- START_SECT(p), NR_SECTS(p));
+ start_sect(p), nr_sects(p));
}
printk(" >\n");
}
@@ -401,7 +405,7 @@ parse_minix(struct parsed_partitions *st
static struct {
unsigned char id;
void (*parse)(struct parsed_partitions *, struct block_device *,
- u32, u32, int);
+ sector_t, sector_t, int);
} subtypes[] = {
{FREEBSD_PARTITION, parse_freebsd},
{NETBSD_PARTITION, parse_netbsd},
@@ -415,7 +419,7 @@ static struct {
int msdos_partition(struct parsed_partitions *state, struct block_device *bdev)
{
- int sector_size = bdev_logical_block_size(bdev) / 512;
+ sector_t sector_size = bdev_logical_block_size(bdev) / 512;
Sector sect;
unsigned char *data;
struct partition *p;
@@ -483,8 +487,8 @@ int msdos_partition(struct parsed_partit
state->next = 5;
for (slot = 1 ; slot <= 4 ; slot++, p++) {
- u32 start = START_SECT(p)*sector_size;
- u32 size = NR_SECTS(p)*sector_size;
+ sector_t start = start_sect(p)*sector_size;
+ sector_t size = nr_sects(p)*sector_size;
if (!size)
continue;
if (is_extended_partition(p)) {
@@ -513,7 +517,7 @@ int msdos_partition(struct parsed_partit
unsigned char id = SYS_IND(p);
int n;
- if (!NR_SECTS(p))
+ if (!nr_sects(p))
continue;
for (n = 0; subtypes[n].parse && id != subtypes[n].id; n++)
@@ -521,8 +525,8 @@ int msdos_partition(struct parsed_partit
if (!subtypes[n].parse)
continue;
- subtypes[n].parse(state, bdev, START_SECT(p)*sector_size,
- NR_SECTS(p)*sector_size, slot);
+ subtypes[n].parse(state, bdev, start_sect(p)*sector_size,
+ nr_sects(p)*sector_size, slot);
}
put_dev_sector(sect);
return 1;
_
--
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