FAT: Add new ioctl VFAT_IOCTL_GET_VOLUME_ID for reading the volume ID.
Signed-off-by: Brian Swetland <swetland@google.com>
diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index aca191b..65e174b 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -754,6 +754,13 @@
return ret;
}
+static int fat_ioctl_volume_id(struct inode *dir)
+{
+ struct super_block *sb = dir->i_sb;
+ struct msdos_sb_info *sbi = MSDOS_SB(sb);
+ return sbi->vol_id;
+}
+
static long fat_dir_ioctl(struct file *filp, unsigned int cmd,
unsigned long arg)
{
@@ -770,6 +777,8 @@
short_only = 0;
both = 1;
break;
+ case VFAT_IOCTL_GET_VOLUME_ID:
+ return fat_ioctl_volume_id(inode);
default:
return fat_generic_ioctl(filp, cmd, arg);
}
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 1510a4d..71af868 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -78,6 +78,7 @@
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 long vol_id; /* volume ID */
int fatent_shift;
struct fatent_operations *fatent_ops;
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 808cac7..1f66735 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -1247,6 +1247,7 @@
struct inode *root_inode = NULL, *fat_inode = NULL;
struct buffer_head *bh;
struct fat_boot_sector *b;
+ struct fat_boot_bsx *bsx;
struct msdos_sb_info *sbi;
u16 logical_sector_size;
u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
@@ -1391,6 +1392,8 @@
goto out_fail;
}
+ bsx = (struct fat_boot_bsx *)(bh->b_data + FAT32_BSX_OFFSET);
+
fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
if (!IS_FSINFO(fsinfo)) {
fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
@@ -1406,8 +1409,14 @@
}
brelse(fsinfo_bh);
+ } else {
+ bsx = (struct fat_boot_bsx *)(bh->b_data + FAT16_BSX_OFFSET);
}
+ /* interpret volume ID as a little endian 32 bit integer */
+ sbi->vol_id = (((u32)bsx->vol_id[0]) | ((u32)bsx->vol_id[1] << 8) |
+ ((u32)bsx->vol_id[2] << 16) | ((u32)bsx->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/linux/msdos_fs.h b/include/linux/msdos_fs.h
index 34066e6..f38d4f0 100644
--- a/include/linux/msdos_fs.h
+++ b/include/linux/msdos_fs.h
@@ -101,6 +101,7 @@
/* <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)
+#define VFAT_IOCTL_GET_VOLUME_ID _IOR('r', 0x12, __u32)
struct fat_boot_sector {
__u8 ignored[3]; /* Boot strap short or near jump */
@@ -138,6 +139,17 @@
__le32 reserved2[4];
};
+struct fat_boot_bsx {
+ __u8 drive; /* drive number */
+ __u8 reserved1;
+ __u8 signature; /* extended boot signature */
+ __u8 vol_id[4]; /* volume ID */
+ __u8 vol_label[11]; /* volume label */
+ __u8 type[8]; /* file system type */
+};
+#define FAT16_BSX_OFFSET 36 /* offset of fat_boot_bsx in FAT12 and FAT16 */
+#define FAT32_BSX_OFFSET 64 /* offset of fat_boot_bsx in FAT32 */
+
struct msdos_dir_entry {
__u8 name[MSDOS_NAME];/* name and extension */
__u8 attr; /* attribute bits */
