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Subject[PATCH v5 1/2] fs: fat: Add fat filesystem partition volume label in local structure
Date
1. Read volume label whe the fat system driver load.
2. Add interface to scan volume label entry.

Signed-off-by: ChenGuanqiao <chen.chenchacha@foxmail.com>
---
fs/fat/dir.c | 29 +++++++++++++++++++++++++++++
fs/fat/fat.h | 2 ++
fs/fat/inode.c | 15 ++++++++++++---
include/uapi/linux/msdos_fs.h | 2 ++
4 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index 81cecbe6d7cf..b369953979e3 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -881,6 +881,35 @@ static int fat_get_short_entry(struct inode *dir, loff_t *pos,
return -ENOENT;
}

+static int fat_get_volume_label_entry(struct inode *dir, loff_t *pos,
+ struct buffer_head **bh,
+ struct msdos_dir_entry **de)
+{
+ while (fat_get_entry(dir, pos, bh, de) >= 0)
+ if (((*de)->attr & ATTR_VOLUME) && (*de)->attr != ATTR_EXT)
+ return 0;
+ return -ENOENT;
+}
+
+int fat_scan_volume_label(struct inode *dir, struct fat_slot_info *sinfo)
+{
+ struct super_block *sb = dir->i_sb;
+
+ sinfo->slot_off = 0;
+ sinfo->bh = NULL;
+ while (fat_get_volume_label_entry(dir, &sinfo->slot_off,
+ &sinfo->bh, &sinfo->de) >= 0) {
+ sinfo->slot_off -= sizeof(*sinfo->de);
+ sinfo->nr_slots = 1;
+ sinfo->i_pos = fat_make_i_pos(sb, sinfo->bh, sinfo->de);
+
+ return 0;
+ }
+
+ return -ENOENT;
+}
+EXPORT_SYMBOL_GPL(fat_scan_volume_label);
+
/*
* The ".." entry can not provide the "struct fat_slot_info" information
* for inode, nor a usable i_pos. So, this function provides some information
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 051dac1ce3be..9e8d525d52c9 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -85,6 +85,7 @@ 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;
@@ -299,6 +300,7 @@ extern int fat_dir_empty(struct inode *dir);
extern int fat_subdirs(struct inode *dir);
extern int fat_scan(struct inode *dir, const unsigned char *name,
struct fat_slot_info *sinfo);
+extern int fat_scan_volume_label(struct inode *dir, struct fat_slot_info *sinfo);
extern int fat_scan_logstart(struct inode *dir, int i_logstart,
struct fat_slot_info *sinfo);
extern int fat_get_dotdot_entry(struct inode *dir, struct buffer_head **bh,
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 30c52394a7ad..e73379a41d49 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 e956704f5fb1..b4fced0988a9 100644
--- a/include/uapi/linux/msdos_fs.h
+++ b/include/uapi/linux/msdos_fs.h
@@ -106,6 +106,8 @@ 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 */
--
2.11.0


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