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Date: Wed, 20 Dec 2017 22:05:47 +0800
From: Chen Guanqiao <chen.chenchacha@...mail.com>
To: hirofumi@...l.parknet.co.jp
Cc: linux-kernel@...r.kernel.org,
Chen Guanqiao <chen.chenchacha@...mail.com>
Subject: [PATCH] fs: fat: add ioctl to modify fat filesystem volume label
The FAT filesystem volume label can be read with FAT_IOCTL_GET_VOLUME_LABEL
and written with FAT_IOCTL_SET_VOLUME_LABEL.
Signed-off-by: Chen Guanqiao <chen.chenchacha@...mail.com>
---
fs/fat/fat.h | 1 +
fs/fat/file.c | 51 +++++++++++++++++++++++++++++++++++++++++++
fs/fat/inode.c | 15 ++++++++++---
include/uapi/linux/msdos_fs.h | 2 ++
4 files changed, 66 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/file.c b/fs/fat/file.c
index 4724cc9ad650..5d2990c44705 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -121,6 +121,53 @@ static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
return put_user(sbi->vol_id, user_attr);
}
+static int fat_ioctl_get_volume_label(struct inode *inode,
+ u32 __user *user_attr)
+{
+ struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+ u8 __user *vol_label = (u8 __user *)user_attr;
+
+ return copy_to_user(vol_label, sbi->vol_label, sizeof(sbi->vol_label));
+}
+
+static int fat_ioctl_set_volume_label(struct inode *inode,
+ u32 __user *user_attr)
+{
+ struct buffer_head *bh;
+ struct fat_boot_sector *b;
+ struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+ u8 __user *vol_label = (u8 __user *)user_attr;
+ u8 label[11];
+
+ if (copy_from_user(label, vol_label, sizeof(label)))
+ return -EFAULT;
+
+ if (sb_rdonly(inode->i_sb))
+ return -EFAULT;
+
+ bh = sb_bread(inode->i_sb, 0);
+ if (bh == NULL) {
+ fat_msg(inode->i_sb, KERN_ERR,
+ "unable to read boot sector to write volume label");
+ return -EFAULT;
+ }
+
+ b = (struct fat_boot_sector *) bh->b_data;
+
+ if (sbi->fat_bits == 32)
+ memcpy(b->fat32.vol_label, label, sizeof(label));
+ else
+ memcpy(b->fat16.vol_label, label, sizeof(label));
+
+ mark_buffer_dirty(bh);
+ sync_dirty_buffer(bh);
+ brelse(bh);
+
+ memcpy(sbi->vol_label, label, sizeof(sbi->vol_label));
+
+ return 0;
+}
+
long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
@@ -133,6 +180,10 @@ long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
return fat_ioctl_set_attributes(filp, user_attr);
case FAT_IOCTL_GET_VOLUME_ID:
return fat_ioctl_get_volume_id(inode, user_attr);
+ case FAT_IOCTL_GET_VOLUME_LABEL:
+ return fat_ioctl_get_volume_label(inode, user_attr);
+ case FAT_IOCTL_SET_VOLUME_LABEL:
+ return fat_ioctl_set_volume_label(inode, user_attr);
default:
return -ENOTTY; /* Inappropriate ioctl for device */
}
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 20a0a89eaca5..9991500c98af 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..799f9a6cb99d 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 _IOR('r', 0x15, __u8[11])
struct fat_boot_sector {
__u8 ignored[3]; /* Boot strap short or near jump */
--
2.15.1
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