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Subject[PATCH v3 2/2] fs: fat: add ioctl method in fat filesystem driver
Date
Signed-off-by: Chen Guanqiao <chen.chenchacha@foxmail.com>
---
fs/fat/file.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 116 insertions(+)

diff --git a/fs/fat/file.c b/fs/fat/file.c
index 4724cc9ad650..972f9aed5b46 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -20,6 +20,25 @@
static long fat_fallocate(struct file *file, int mode,
loff_t offset, loff_t len);

+static int fat_check_volume_label(const char *label)
+{
+ int i;
+
+ for (i=0; i<11; ++i) {
+ switch (label[i]) {
+ case 0x20:
+ case 'A' ... 'Z':
+ case '0' ... '9':
+ continue;
+ case 0:
+ return 0;
+ default:
+ return -EINVAL;
+ }
+ }
+ return -EINVAL;
+}
+
static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
{
u32 attr;
@@ -121,10 +140,103 @@ 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,
+ u8 __user *vol_label)
+{
+ int ret = 0;
+ struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+
+ if (copy_to_user(vol_label, sbi->vol_label, sizeof(sbi->vol_label)))
+ ret = -EFAULT;
+
+ return ret;
+}
+
+static int fat_ioctl_set_volume_label(struct file *file,
+ u8 __user *vol_label)
+{
+ int err;
+ u8 label[11];
+ struct buffer_head *bh;
+ struct fat_boot_sector *b;
+ struct msdos_dir_entry *entry;
+ struct inode *inode = file_inode(file);
+ struct super_block *sb = inode->i_sb;
+ struct msdos_sb_info *sbi = MSDOS_SB(sb);
+
+ if (copy_from_user(label, vol_label, sizeof(label))) {
+ err = -EFAULT;
+ goto out;
+ }
+
+ if (fat_check_volume_label(label)) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ err = mnt_want_write_file(file);
+ if (err)
+ goto out;
+
+ inode_lock(inode);
+
+ if (sb_rdonly(inode->i_sb)) {
+ err = -EROFS;
+ goto out_unlock_inode;
+ }
+
+ /* handling sector's vol_label */
+ 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");
+ err = -EFAULT;
+ goto out_unlock_inode;
+ }
+
+ b = (struct fat_boot_sector *) bh->b_data;
+
+ if (b->fat16.signature == 0x28 || b->fat32.signature == 0x28) {
+ fat_msg(inode->i_sb, KERN_ERR,
+ "volume label supported since OS/2 1.2 and MS-DOS 4.0 "
+ "and higher");
+ err = -EFAULT;
+ goto out_unlock_inode;
+ }
+
+ lock_buffer(bh);
+ 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);
+ unlock_buffer(bh);
+ brelse(bh);
+
+ /* handling root directory's vol_label */
+ bh = sb_bread(sb, sbi->dir_start);
+ entry = &((struct msdos_dir_entry *)(bh->b_data))[0];
+
+ lock_buffer(bh);
+ memcpy(entry->name, label, sizeof(entry->name));
+ mark_buffer_dirty(bh);
+ unlock_buffer(bh);
+ brelse(bh);
+
+ memcpy(sbi->vol_label, label, sizeof(sbi->vol_label));
+
+ out_unlock_inode:
+ inode_unlock(inode);
+ out:
+ return err;
+}
+
long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
u32 __user *user_attr = (u32 __user *)arg;
+ u8 __user *user_vol_label = (u8 __user *)arg;

switch (cmd) {
case FAT_IOCTL_GET_ATTRIBUTES:
@@ -133,6 +245,10 @@ 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_vol_label);
+ case FAT_IOCTL_SET_VOLUME_LABEL:
+ return fat_ioctl_set_volume_label(filp, user_vol_label);
default:
return -ENOTTY; /* Inappropriate ioctl for device */
}
--
2.15.1

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