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

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

fs/fat/fat.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

fs/fat/file.c

+8 −0
Original line number Diff line number Diff line
@@ -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 */

	}

fs/fat/inode.c

+12 −0
Original line number Diff line number Diff line
@@ -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;

include/uapi/linux/msdos_fs.h

+10 −0
Original line number Diff line number Diff line
@@ -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;

	};