fat: add extended fileds to struct fat_boot_sector

Later we will need "state" field to check if volume was cleanly unmounted.

Signed-off-by: Oleksij Rempel <bug-track@fisher-privat.net>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 28 insertions, 8 deletions

diff --git a/include/uapi/linux/msdos_fs.h b/include/uapi/linux/msdos_fs.h
index 996719f82e28..b9f12450efe8 100644
--- a/include/uapi/linux/msdos_fs.h
+++ b/include/uapi/linux/msdos_fs.h
@@ -120,14 +120,34 @@ struct fat_boot_sector {
         __le32  hidden;         /* hidden sectors (unused) */
         __le32  total_sect;     /* number of sectors (if sectors == 0) */
 
-        /* The following fields are only used by FAT32 */
-        __le32  fat32_length;   /* sectors/FAT */
-        __le16  flags;          /* bit 8: fat mirroring, low 4: active fat */
-        __u8    version[2];     /* major, minor filesystem version */
-        __le32  root_cluster;   /* first cluster in root directory */
-        __le16  info_sector;    /* filesystem info sector */
-        __le16  backup_boot;    /* backup boot sector */
-        __le16  reserved2[6];   /* Unused */
+        union {
+                struct {
+                        /*  Extended BPB Fields for FAT16 */
+                        __u8    drive_number;   /* Physical drive number */
+                        __u8    state;          /* undocumented, but used
+                                                   for mount state. */
+                        /* other fiealds are not added here */
+                } fat16;
+
+                struct {
+                        /* only used by FAT32 */
+                        __le32  length;         /* sectors/FAT */
+                        __le16  flags;          /* bit 8: fat mirroring,
+                                                   low 4: active fat */
+                        __u8    version[2];     /* major, minor filesystem
+                                                   version */
+                        __le32  root_cluster;   /* first cluster in
+                                                   root directory */
+                        __le16  info_sector;    /* filesystem info sector */
+                        __le16  backup_boot;    /* backup boot sector */
+                        __le16  reserved2[6];   /* Unused */
+                        /* Extended BPB Fields for FAT32 */
+                        __u8    drive_number;   /* Physical drive number */
+                        __u8    state;          /* undocumented, but used
+                                                   for mount state. */
+                        /* other fiealds are not added here */
+                } fat32;
+        };
 };
 
 struct fat_boot_fsinfo {