The FAT filesystem partition volume label can be read with
FAT_IOCTL_GET_VOLUME_LABEL and written with FAT_IOCTL_SET_VOLUME_LABEL.
FAT volume label (volume name) is exactly same stored in boot sector and root
directory. Thus, the boot sector just needs to be upgrade when the label
writing.
v5:
1. find the volume label entry through the scan function.
2. the volume label only retains the d-characters (reference from Ecma-107).
v4:
1. read/write volume label from/to the location of the respective version.
2. correct volume label check reference from mkfs.fat.
3. fixed some code issue.
v3:
1. write volume label both boot sector and root directory.
v2:
1. add filesystem version check.
2. add diretory permissions check.
3. add volume label string check.
4. fixed part of return value.
5. fixed some indent issue.
6. remove sync_dirty_buffer().
ChenGuanqiao (2):
fs: fat: Add fat filesystem partition volume label in local structure
fs: fat: add ioctl method in fat filesystem driver
fs/fat/dir.c | 29 +++++++++++
fs/fat/fat.h | 2 +
fs/fat/file.c | 116 ++++++++++++++++++++++++++++++++++++++++++
fs/fat/inode.c | 15 ++++--
include/uapi/linux/msdos_fs.h | 2 +
5 files changed, 161 insertions(+), 3 deletions(-)
--
2.11.0
1. Read volume label whe the fat system driver load.
2. Add interface to scan volume label entry.
Signed-off-by: ChenGuanqiao <[email protected]>
---
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
Signed-off-by: ChenGuanqiao <[email protected]>
---
fs/fat/file.c | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 116 insertions(+)
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 4724cc9ad650..517941c7bce4 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -15,11 +15,35 @@
#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);
+/* the characters in this field shall be d-characters, and unused byte shall be set to 0x20. */
+static int fat_format_d_characters(char *label, unsigned long len)
+{
+ int i;
+
+ for (i=0; i<len; ++i) {
+ switch (label[i]) {
+ case '0' ... '9':
+ case 'A' ... 'Z':
+ case '_':
+ continue;
+ default:
+ break;
+ }
+ break;
+ }
+
+ for (; i<len; ++i)
+ label[i] = 0x20;
+
+ return len;
+}
+
static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
{
u32 attr;
@@ -121,10 +145,98 @@ 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 err = 0;
+ struct fat_slot_info sinfo;
+
+ err = fat_scan_volume_label(inode, &sinfo);
+ if (err)
+ goto out;
+
+ if (copy_to_user(vol_label, sinfo.de->name, MSDOS_NAME))
+ err = -EFAULT;
+
+ brelse(sinfo.bh);
+out:
+ return err;
+}
+
+static int fat_ioctl_set_volume_label(struct file *file,
+ u8 __user *vol_label)
+{
+ int err = 0;
+ u8 label[MSDOS_NAME];
+ struct buffer_head *bh;
+ struct fat_boot_sector *b;
+ struct fat_slot_info sinfo;
+ 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;
+ }
+
+ fat_format_d_characters(label, sizeof(label));
+ err = mnt_want_write_file(file);
+ if (err)
+ goto out;
+
+ /* Update sector's vol_label */
+ bh = sb_bread(sb, 0);
+ if (bh == NULL) {
+ fat_msg(sb, KERN_ERR,
+ "unable to read boot sector to write volume label");
+ err = -EIO;
+ goto out_drop_file;
+ }
+
+ b = (struct fat_boot_sector *)bh->b_data;
+
+ 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);
+ err = sync_dirty_buffer(bh);
+ brelse(bh);
+ if (err)
+ goto out_drop_file;
+
+ /* updates root directory's vol_label */
+ err = fat_scan_volume_label(inode, &sinfo);
+ if (err)
+ goto out_drop_file;
+
+ bh = sinfo.bh;
+ lock_buffer(bh);
+ memcpy(sinfo.de->name, label, sizeof(sinfo.de->name));
+ mark_buffer_dirty(bh);
+ unlock_buffer(bh);
+ err = sync_dirty_buffer(bh);
+ brelse(bh);
+ if (err)
+ goto out_drop_file;
+
+ memcpy(sbi->vol_label, label, sizeof(sbi->vol_label));
+
+out_drop_file:
+ mnt_drop_write_file(file);
+ 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 */
}
--
2.11.0
ChenGuanqiao <[email protected]> writes:
> +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);
Why do you need sinfo?
--
OGAWA Hirofumi <[email protected]>
ChenGuanqiao <[email protected]> writes:
> +/* the characters in this field shall be d-characters, and unused byte shall be set to 0x20. */
> +static int fat_format_d_characters(char *label, unsigned long len)
> +{
> + int i;
> +
> + for (i=0; i<len; ++i) {
> + switch (label[i]) {
> + case '0' ... '9':
> + case 'A' ... 'Z':
> + case '_':
> + continue;
> + default:
> + break;
> + }
> + break;
> + }
> +
> + for (; i<len; ++i)
> + label[i] = 0x20;
> +
> + return len;
> +}
It should not accept and overwrite invalid char, return -EINVAL.
> +static int fat_ioctl_get_volume_label(struct inode *inode,
> + u8 __user *vol_label)
> +{
> + int err = 0;
> + struct fat_slot_info sinfo;
> +
> + err = fat_scan_volume_label(inode, &sinfo);
> + if (err)
> + goto out;
It needs to take inode read lock.
> + if (copy_to_user(vol_label, sinfo.de->name, MSDOS_NAME))
> + err = -EFAULT;
> +
> + brelse(sinfo.bh);
> +out:
> + return err;
> +}
> +
> +static int fat_ioctl_set_volume_label(struct file *file,
> + u8 __user *vol_label)
> +{
[...]
> + b = (struct fat_boot_sector *)bh->b_data;
> +
> + lock_buffer(bh);
Probably, sb->s_umount to exclusive with remount update.
> + 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);
> + err = sync_dirty_buffer(bh);
> + brelse(bh);
> + if (err)
> + goto out_drop_file;
It should not update before preparing is done and checking error.
> + /* updates root directory's vol_label */
> + err = fat_scan_volume_label(inode, &sinfo);
> + if (err)
> + goto out_drop_file;
It should add entry if no volume label.
> + lock_buffer(bh);
inode write lock.
> + memcpy(sinfo.de->name, label, sizeof(sinfo.de->name));
> + mark_buffer_dirty(bh);
> + unlock_buffer(bh);
Thanks.
--
OGAWA Hirofumi <[email protected]>