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Subject[PATCH v9 3/3] fs: fat: add ioctl method in fat filesystem driver
Date
Signed-off-by: Chen Guanqiao <chen.chenchacha@foxmail.com>
---
fs/fat/file.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 145 insertions(+)

diff --git a/fs/fat/file.c b/fs/fat/file.c
index 4724cc9ad650..e87c5ae9208e 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -15,11 +15,46 @@
#include <linux/fsnotify.h>
#include <linux/security.h>
#include <linux/falloc.h>
+#include <linux/ctype.h>
#include "fat.h"

static long fat_fallocate(struct file *file, int mode,
loff_t offset, loff_t len);

+static int fat_generate_volume_name(char *label, unsigned long len)
+{
+ unsigned int i;
+
+ /* For reasons, refer to namei_msdos.c:msdos_format_name() */
+ if (label[0] == 0xE5)
+ label[0] = 0x05;
+
+ for (i = 0; i < len; ++i) {
+ char c = label[i];
+ /* valid character contains d-characters and all extended ASCII
+ * characters.
+ * remaining empty spaces are padded by 0x20.
+ */
+ if (c <= 0x7f)
+ switch (label[i]) {
+ case 'a' ... 'z':
+ label[i] = __toupper(label[i]);
+ case 'A' ... 'Z':
+ case '0' ... '9':
+ case '_':
+ case 0x20:
+ continue;
+ case 0:
+ label[i] = 0x20;
+ continue;
+ default:
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
{
u32 attr;
@@ -121,10 +156,116 @@ 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 *label)
+{
+ struct super_block *sb = inode->i_sb;
+ struct buffer_head *bh;
+ struct msdos_dir_entry *de;
+ int err;
+
+ inode = d_inode(sb->s_root);
+ inode_lock_shared(inode);
+
+ err = fat_get_volume_label_entry(inode, &bh, &de);
+ if (err)
+ goto out;
+
+ if (copy_to_user(label, de->name, MSDOS_NAME))
+ err = -EFAULT;
+
+ brelse(bh);
+out:
+ inode_unlock_shared(inode);
+
+ return err;
+}
+
+static int fat_ioctl_set_volume_label(struct file *file, u8 __user *label)
+{
+ struct inode *inode = file_inode(file);
+ struct super_block *sb = inode->i_sb;
+ struct timespec ts;
+ struct buffer_head *boot_bh;
+ struct buffer_head *vol_bh;
+ struct msdos_dir_entry *de;
+ struct fat_boot_sector *b;
+ u8 buf[MSDOS_NAME];
+ int err;
+
+ inode = d_inode(sb->s_root);
+
+ if (copy_from_user(buf, label, sizeof(buf))) {
+ err = -EFAULT;
+ goto out;
+ }
+
+ err = fat_generate_volume_name(buf, sizeof(buf));
+ if (err)
+ goto out;
+
+ down_write(&sb->s_umount);
+ err = mnt_want_write_file(file);
+ if (err)
+ goto out;
+
+ inode_lock(inode);
+
+ /* Updates root directory's label */
+ err = fat_get_volume_label_entry(inode, &vol_bh, &de);
+ ts = current_time(inode);
+ if (err) {
+ /* Create volume label entry */
+ err = fat_add_volume_label_entry(inode, buf, &ts);
+ if (err)
+ goto out_vol_brelse;
+ } else {
+ /* Write to root directory */
+ memcpy(de->name, buf, sizeof(de->name));
+ inode->i_ctime = inode->i_mtime = inode->i_atime = ts;
+
+ mark_buffer_dirty(vol_bh);
+ }
+
+ /* Update sector's label */
+ boot_bh = sb_bread(sb, 0);
+ if (boot_bh == NULL) {
+ fat_msg(sb, KERN_ERR,
+ "unable to read boot sector to write volume label");
+ err = -EIO;
+ goto out_boot_brelse;
+ }
+
+ b = (struct fat_boot_sector *)boot_bh->b_data;
+ if (MSDOS_SB(sb)->fat_bits == 32)
+ memcpy(b->fat32.vol_label, buf, sizeof(buf));
+ else
+ memcpy(b->fat16.vol_label, buf, sizeof(buf));
+
+ mark_buffer_dirty(boot_bh);
+
+ /* Synchronize the data together */
+ err = sync_dirty_buffer(boot_bh);
+ if (err)
+ goto out_boot_brelse;
+
+out_boot_brelse:
+ brelse(boot_bh);
+out_vol_brelse:
+ brelse(vol_bh);
+
+ inode_unlock(inode);
+ mnt_drop_write_file(file);
+ up_write(&sb->s_umount);
+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 +274,10 @@ 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 */
}
--
2.14.3

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