From 6e5b93ee55d401f1619092fb675b57c28c9ed7ec Mon Sep 17 00:00:00 2001 From: Mike Lockwood Date: Mon, 8 Jul 2013 16:00:46 -0700 Subject: [PATCH] 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: Bintian Wang Cc: dmitry pervushin Cc: Mike Lockwood Cc: Colin Cross Acked-by: OGAWA Hirofumi Cc: John Stultz Cc: Sean McNeil Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fat/fat.h | 1 + fs/fat/file.c | 8 ++++++++ fs/fat/inode.c | 12 ++++++++++++ include/uapi/linux/msdos_fs.h | 10 ++++++++++ 4 files changed, 31 insertions(+) diff --git a/fs/fat/fat.h b/fs/fat/fat.h index 21664fcf3616..4241e6f39e86 100644 --- a/fs/fat/fat.h +++ b/fs/fat/fat.h @@ -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; diff --git a/fs/fat/file.c b/fs/fat/file.c index b0b632e50ddb..9b104f543056 100644 --- a/fs/fat/file.c +++ b/fs/fat/file.c @@ -114,6 +114,12 @@ out: 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 */ } diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 5d4513cb1b3c..11b51bb55b42 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -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; diff --git a/include/uapi/linux/msdos_fs.h b/include/uapi/linux/msdos_fs.h index f055e58b3147..e284ff919d6e 100644 --- a/include/uapi/linux/msdos_fs.h +++ b/include/uapi/linux/msdos_fs.h @@ -104,6 +104,8 @@ struct __fat_dirent { /* 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; }; -- 2.30.2