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fatfs: add FAT_IOCTL_GET_VOLUME_ID

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This patch, originally from Android kernel, adds vfat ioctl command
FAT_IOCTL_GET_VOLUME_ID, with this command we can get the vfat volume ID
using following code:

	ioctl(fd, FAT_IOCTL_GET_VOLUME_ID, &volume_ID)

This patch is a modified version of the patch by Mike Lockwood, with
changes from Dmitry Pervushin, who noticed the original patch makes some
volume IDs abiguous with error returns: for example, if volume id is
0xFFFFFDAD, that matches -ENOIOCTLCMD, we get "FFFFFFFF" from the user
space.

So add a parameter to ioctl to get the correct volume ID.

Android uses vfat volume ID to identify different sd card, when a new sd
card is inserted to device, android can scan the media on it and pop up
new contents.

Signed-off-by: Bintian Wang <bintian.wang@linaro.org>
Cc: dmitry pervushin <dpervushin@gmail.com>
Cc: Mike Lockwood <lockwood@android.com>
Cc: Colin Cross <ccross@android.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Sean McNeil <sean@mcneil.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Lockwood
2013-07-08 16:00:46 -07:00
committed by Linus Torvalds
parent 4e80b1880c
commit 6e5b93ee55
4 changed files with 31 additions and 0 deletions
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10
include/uapi/linux/msdos_fs.h
View File

@@ -104,6 +104,8 @@ struct __fat_dirent {
/* <linux/videotext.h> has used 0x72 ('r') in collision, so skip a few */
#define FAT_IOCTL_GET_ATTRIBUTES _IOR('r', 0x10, __u32)
#define FAT_IOCTL_SET_ATTRIBUTES _IOW('r', 0x11, __u32)
/*Android kernel has used 0x12, so we use 0x13*/
#define FAT_IOCTL_GET_VOLUME_ID _IOR('r', 0x13, __u32)
struct fat_boot_sector {
__u8 ignored[3]; /* Boot strap short or near jump */
@@ -128,6 +130,10 @@ struct fat_boot_sector {
__u8 drive_number; /* Physical drive number */
__u8 state; /* undocumented, but used
for mount state. */
__u8 signature; /* extended boot signature */
__u8 vol_id[4]; /* volume ID */
__u8 vol_label[11]; /* volume label */
__u8 fs_type[8]; /* file system type */
/* other fiealds are not added here */
} fat16;
@@ -147,6 +153,10 @@ struct fat_boot_sector {
__u8 drive_number; /* Physical drive number */
__u8 state; /* undocumented, but used
for mount state. */
__u8 signature; /* extended boot signature */
__u8 vol_id[4]; /* volume ID */
__u8 vol_label[11]; /* volume label */
__u8 fs_type[8]; /* file system type */
/* other fiealds are not added here */
} fat32;
};