From 0607fd02587a6b4b086dc746d63123c1f284db68 Mon Sep 17 00:00:00 2001 From: Frank Seidel Date: Mon, 28 Apr 2008 02:16:31 -0700 Subject: [PATCH] fat: detect media without partition table correctly I received a complaint that some FAT formated medias (e.g. sd memory cards) trigger a "unknown partition table" message even though there is no partition table and they work correctly, while in general (when e.g. formated with mkdosfs or even Windows Vista) this message is not shown. Currently this seems only to happen when the medias get formatted with Windows XP (and possibly Win 2000). Then the boot indicator byte contains garbage (part of text message) and so do the other parts checked by msdos_paritition which then later triggers this message. References: novell bug #364365 Most fat formatted media without partition table contains zeros in the boot indication and the other tested bytes and so falls through the checks in msdos_partition, leading it to return with 1 (all is fine). But some (e.g. WinXP formatted) fat fomated medias don't use boot_ind and so the check fails and causes a "unkown partition table" warning eventhough there is none and everything would be fine. This additional check directly verifies if there is a fat formatted medium without a partition table. Signed-off-by: Frank Seidel Cc: Andreas Dilger Acked-by: OGAWA Hirofumi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/partitions/msdos.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/fs/partitions/msdos.c b/fs/partitions/msdos.c index 5567ec0d03a..796511886f2 100644 --- a/fs/partitions/msdos.c +++ b/fs/partitions/msdos.c @@ -18,7 +18,7 @@ * * Re-organised Feb 1998 Russell King */ - +#include #include "check.h" #include "msdos.h" @@ -419,6 +419,7 @@ int msdos_partition(struct parsed_partitions *state, struct block_device *bdev) Sector sect; unsigned char *data; struct partition *p; + struct fat_boot_sector *fb; int slot; data = read_dev_sector(bdev, 0, §); @@ -444,8 +445,21 @@ int msdos_partition(struct parsed_partitions *state, struct block_device *bdev) p = (struct partition *) (data + 0x1be); for (slot = 1; slot <= 4; slot++, p++) { if (p->boot_ind != 0 && p->boot_ind != 0x80) { - put_dev_sector(sect); - return 0; + /* + * Even without a valid boot inidicator value + * its still possible this is valid FAT filesystem + * without a partition table. + */ + fb = (struct fat_boot_sector *) data; + if (slot == 1 && fb->reserved && fb->fats + && fat_valid_media(fb->media)) { + printk("\n"); + put_dev_sector(sect); + return 1; + } else { + put_dev_sector(sect); + return 0; + } } } -- 2.41.1