Commit 6e5b93ee authored by Mike Lockwood's avatar Mike Lockwood Committed by Linus Torvalds

fatfs: add FAT_IOCTL_GET_VOLUME_ID

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: default avatarBintian 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: default avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Sean McNeil <sean@mcneil.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4e80b188
......@@ -86,6 +86,7 @@ struct msdos_sb_info {
const void *dir_ops; /* Opaque; default directory operations */
int dir_per_block; /* dir entries per block */
int dir_per_block_bits; /* log2(dir_per_block) */
unsigned int vol_id; /*volume ID*/
int fatent_shift;
struct fatent_operations *fatent_ops;
......
......@@ -114,6 +114,12 @@ static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
return err;
}
static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
{
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
return put_user(sbi->vol_id, user_attr);
}
long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
......@@ -124,6 +130,8 @@ long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
return fat_ioctl_get_attributes(inode, user_attr);
case FAT_IOCTL_SET_ATTRIBUTES:
return fat_ioctl_set_attributes(filp, user_attr);
case FAT_IOCTL_GET_VOLUME_ID:
return fat_ioctl_get_volume_id(inode, user_attr);
default:
return -ENOTTY; /* Inappropriate ioctl for device */
}
......
......@@ -1415,6 +1415,18 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
brelse(fsinfo_bh);
}
/* interpret volume ID as a little endian 32 bit integer */
if (sbi->fat_bits == 32)
sbi->vol_id = (((u32)b->fat32.vol_id[0]) |
((u32)b->fat32.vol_id[1] << 8) |
((u32)b->fat32.vol_id[2] << 16) |
((u32)b->fat32.vol_id[3] << 24));
else /* fat 16 or 12 */
sbi->vol_id = (((u32)b->fat16.vol_id[0]) |
((u32)b->fat16.vol_id[1] << 8) |
((u32)b->fat16.vol_id[2] << 16) |
((u32)b->fat16.vol_id[3] << 24));
sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
......
......@@ -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;
};
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment