[PATCH v3 1/2] fs: fat: add fat filesystem partition volume label in local structure

From: Chen Guanqiao
Date: Sat Dec 23 2017 - 03:32:46 EST


Signed-off-by: Chen Guanqiao <chen.chenchacha@xxxxxxxxxxx>
---
fs/fat/fat.h | 1 +
fs/fat/inode.c | 15 ++++++++++++---
include/uapi/linux/msdos_fs.h | 2 ++
3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 8fc1093da47d..204012c94421 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -86,6 +86,7 @@ struct msdos_sb_info {
int dir_per_block; /* dir entries per block */
int dir_per_block_bits; /* log2(dir_per_block) */
unsigned int vol_id; /*volume ID*/
+ char vol_label[11]; /*volume label*/

int fatent_shift;
const struct fatent_operations *fatent_ops;
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 20a0a89eaca5..a97b6314ef33 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -45,12 +45,14 @@ struct fat_bios_param_block {

u8 fat16_state;
u32 fat16_vol_id;
+ u8 fat16_vol_label[11];

u32 fat32_length;
u32 fat32_root_cluster;
u16 fat32_info_sector;
u8 fat32_state;
u32 fat32_vol_id;
+ u8 fat32_vol_label[11];
};

static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
@@ -1460,12 +1462,16 @@ static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b,

bpb->fat16_state = b->fat16.state;
bpb->fat16_vol_id = get_unaligned_le32(b->fat16.vol_id);
+ memcpy(bpb->fat16_vol_label, b->fat16.vol_label,
+ sizeof(bpb->fat16_vol_label));

bpb->fat32_length = le32_to_cpu(b->fat32.length);
bpb->fat32_root_cluster = le32_to_cpu(b->fat32.root_cluster);
bpb->fat32_info_sector = le16_to_cpu(b->fat32.info_sector);
bpb->fat32_state = b->fat32.state;
bpb->fat32_vol_id = get_unaligned_le32(b->fat32.vol_id);
+ memcpy(bpb->fat32_vol_label, b->fat32.vol_label,
+ sizeof(bpb->fat32_vol_label));

/* Validate this looks like a FAT filesystem BPB */
if (!bpb->fat_reserved) {
@@ -1723,11 +1729,14 @@ 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)
+ /* interpret volume ID and label as a little endian 32 bit integer */
+ if (sbi->fat_bits == 32) {
sbi->vol_id = bpb.fat32_vol_id;
- else /* fat 16 or 12 */
+ memcpy(sbi->vol_label, bpb.fat32_vol_label, sizeof(sbi->vol_label));
+ } else { /* fat 16 or 12 */
sbi->vol_id = bpb.fat16_vol_id;
+ memcpy(sbi->vol_label, bpb.fat16_vol_label, sizeof(sbi->vol_label));
+ }

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 a45d0754102e..90d2d6f3d908 100644
--- a/include/uapi/linux/msdos_fs.h
+++ b/include/uapi/linux/msdos_fs.h
@@ -107,6 +107,8 @@ struct __fat_dirent {
#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)
+#define FAT_IOCTL_GET_VOLUME_LABEL _IOR('r', 0x14, __u8[11])
+#define FAT_IOCTL_SET_VOLUME_LABEL _IOW('r', 0x15, __u8[11])

struct fat_boot_sector {
__u8 ignored[3]; /* Boot strap short or near jump */
--
2.15.1