* [PATCH v3 1/1] exfat: Add support for FS_IOC_{GET,SET}FSLABEL
2025-08-21 15:09 [PATCH v3 0/1] exfat: Add support for FS_IOC_{GET,SET}FSLABEL Ethan Ferguson
@ 2025-08-21 15:09 ` Ethan Ferguson
2025-08-22 15:53 ` kernel test robot
0 siblings, 1 reply; 3+ messages in thread
From: Ethan Ferguson @ 2025-08-21 15:09 UTC (permalink / raw)
To: linkinjeon, sj1557.seo, yuezhang.mo
Cc: linux-fsdevel, linux-kernel, Ethan Ferguson
Add support for reading / writing to the exfat volume label from the
FS_IOC_GETFSLABEL and FS_IOC_SETFSLABEL ioctls
Signed-off-by: Ethan Ferguson <ethan.ferguson@zetier.com>
Lazy label loading, better char conversion
---
fs/exfat/exfat_fs.h | 3 +
fs/exfat/exfat_raw.h | 6 ++
fs/exfat/file.c | 78 ++++++++++++++++++
fs/exfat/super.c | 190 +++++++++++++++++++++++++++++++++++++++++++
4 files changed, 277 insertions(+)
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index f8ead4d47ef0..19b8524e5b7d 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -267,6 +267,7 @@ struct exfat_sb_info {
struct buffer_head **vol_amap; /* allocation bitmap */
unsigned short *vol_utbl; /* upcase table */
+ unsigned short *volume_label; /* volume name */
unsigned int clu_srch_ptr; /* cluster search pointer */
unsigned int used_clusters; /* number of used clusters */
@@ -431,6 +432,8 @@ static inline loff_t exfat_ondisk_size(const struct inode *inode)
/* super.c */
int exfat_set_volume_dirty(struct super_block *sb);
int exfat_clear_volume_dirty(struct super_block *sb);
+int exfat_read_volume_label(struct super_block *sb);
+int exfat_write_volume_label(struct super_block *sb, struct exfat_uni_name *uniname);
/* fatent.c */
#define exfat_get_next_cluster(sb, pclu) exfat_ent_get(sb, *(pclu), pclu)
diff --git a/fs/exfat/exfat_raw.h b/fs/exfat/exfat_raw.h
index 971a1ccd0e89..4082fa7b8c14 100644
--- a/fs/exfat/exfat_raw.h
+++ b/fs/exfat/exfat_raw.h
@@ -80,6 +80,7 @@
#define BOOTSEC_OLDBPB_LEN 53
#define EXFAT_FILE_NAME_LEN 15
+#define EXFAT_VOLUME_LABEL_LEN 11
#define EXFAT_MIN_SECT_SIZE_BITS 9
#define EXFAT_MAX_SECT_SIZE_BITS 12
@@ -159,6 +160,11 @@ struct exfat_dentry {
__le32 start_clu;
__le64 size;
} __packed upcase; /* up-case table directory entry */
+ struct {
+ __u8 char_count;
+ __le16 volume_label[EXFAT_VOLUME_LABEL_LEN];
+ __u8 reserved[8];
+ } __packed volume_label; /* volume label directory entry */
struct {
__u8 flags;
__u8 vendor_guid[16];
diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index 538d2b6ac2ec..12c8ae450193 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -12,6 +12,7 @@
#include <linux/security.h>
#include <linux/msdos_fs.h>
#include <linux/writeback.h>
+#include "../nls/nls_ucs2_utils.h"
#include "exfat_raw.h"
#include "exfat_fs.h"
@@ -486,6 +487,79 @@ static int exfat_ioctl_shutdown(struct super_block *sb, unsigned long arg)
return exfat_force_shutdown(sb, flags);
}
+static int exfat_ioctl_get_volume_label(struct super_block *sb, unsigned long arg)
+{
+ int ret;
+ char utf8[FSLABEL_MAX] = {0};
+ struct exfat_uni_name *uniname;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+ uniname = kmalloc(sizeof(struct exfat_uni_name), GFP_KERNEL);
+ if (!uniname)
+ return -ENOMEM;
+
+ ret = exfat_read_volume_label(sb);
+ if (ret < 0)
+ goto cleanup;
+
+ memcpy(uniname->name, sbi->volume_label,
+ EXFAT_VOLUME_LABEL_LEN * sizeof(short));
+ uniname->name[EXFAT_VOLUME_LABEL_LEN] = 0x0000;
+ uniname->name_len = UniStrnlen(uniname->name, EXFAT_VOLUME_LABEL_LEN);
+
+ ret = exfat_utf16_to_nls(sb, uniname, utf8, FSLABEL_MAX);
+
+ if (copy_to_user((char __user *)arg, utf8, FSLABEL_MAX)) {
+ ret = -EFAULT;
+ goto cleanup;
+ }
+
+cleanup:
+ kfree(uniname);
+ return 0;
+}
+
+static int exfat_ioctl_set_volume_label(struct super_block *sb, unsigned long arg)
+{
+ int ret, lossy;
+ char utf8[FSLABEL_MAX];
+ struct exfat_uni_name *uniname;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ uniname = kmalloc(sizeof(struct exfat_uni_name), GFP_KERNEL);
+ if (!uniname)
+ return -ENOMEM;
+
+ if (copy_from_user(utf8, (char __user *)arg, FSLABEL_MAX)) {
+ ret = -EFAULT;
+ goto cleanup;
+ }
+
+ if (utf8[0]) {
+ exfat_nls_to_utf16(sb, utf8, strnlen(utf8, FSLABEL_MAX), uniname, &lossy);
+ if (lossy & NLS_NAME_LOSSY) {
+ ret = -EINVAL;
+ goto cleanup;
+ }
+ } else {
+ uniname->name[0] = 0x0000;
+ uniname->name_len = 0;
+ }
+
+ if (uniname->name_len > EXFAT_VOLUME_LABEL_LEN) {
+ exfat_info(sb, "Volume label length too long, truncating");
+ uniname->name_len = EXFAT_VOLUME_LABEL_LEN;
+ }
+
+ ret = exfat_write_volume_label(sb, uniname);
+
+cleanup:
+ kfree(uniname);
+ return ret;
+}
+
long exfat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
@@ -500,6 +574,10 @@ long exfat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
return exfat_ioctl_shutdown(inode->i_sb, arg);
case FITRIM:
return exfat_ioctl_fitrim(inode, arg);
+ case FS_IOC_GETFSLABEL:
+ return exfat_ioctl_get_volume_label(inode->i_sb, arg);
+ case FS_IOC_SETFSLABEL:
+ return exfat_ioctl_set_volume_label(inode->i_sb, arg);
default:
return -ENOTTY;
}
diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index 8926e63f5bb7..7aee6ea594d8 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -18,6 +18,7 @@
#include <linux/nls.h>
#include <linux/buffer_head.h>
#include <linux/magic.h>
+#include "../nls/nls_ucs2_utils.h"
#include "exfat_raw.h"
#include "exfat_fs.h"
@@ -573,6 +574,194 @@ static int exfat_verify_boot_region(struct super_block *sb)
return 0;
}
+static int exfat_get_volume_label_ptrs(struct super_block *sb,
+ struct buffer_head **out_bh,
+ struct exfat_dentry **out_dentry,
+ bool find_new)
+{
+ int i, ret;
+ unsigned int type;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+ struct exfat_chain clu;
+ struct exfat_dentry *ep, *deleted_ep = NULL;
+ struct buffer_head *bh, *deleted_bh;
+
+ clu.dir = sbi->root_dir;
+ clu.flags = ALLOC_FAT_CHAIN;
+
+ while (clu.dir != EXFAT_EOF_CLUSTER) {
+ for (i = 0; i < sbi->dentries_per_clu; i++) {
+ ep = exfat_get_dentry(sb, &clu, i, &bh);
+
+ if (!ep) {
+ ret = -EIO;
+ goto end;
+ }
+
+ type = exfat_get_entry_type(ep);
+ if (type == TYPE_DELETED && !deleted_ep && find_new) {
+ deleted_ep = ep;
+ deleted_bh = bh;
+ continue;
+ }
+
+ if (type == TYPE_UNUSED) {
+ if (find_new) {
+ brelse(bh);
+ ret = -ENOENT;
+ goto end;
+ }
+
+ if (deleted_ep) {
+ brelse(bh);
+ goto end;
+ }
+
+ // Last dentry in cluster
+ if (i == sbi->dentries_per_clu - 1) {
+ // TODO allocate new cluster
+ brelse(bh);
+ ret = -ENOSPC;
+ goto end;
+ }
+
+ deleted_ep = ep;
+ deleted_bh = bh;
+
+ ep = exfat_get_dentry(sb, &clu, i + 1, &bh);
+ memset(ep, 0, sizeof(struct exfat_dentry));
+ ep->type = EXFAT_UNUSED;
+ exfat_update_bh(bh, true);
+ brelse(bh);
+
+ goto end;
+ }
+
+ if (type == TYPE_VOLUME) {
+ *out_bh = bh;
+ *out_dentry = ep;
+
+ if (deleted_ep)
+ brelse(deleted_bh);
+
+ return 0;
+ }
+
+ brelse(bh);
+ }
+
+ if (exfat_get_next_cluster(sb, &(clu.dir))) {
+ ret = -EIO;
+ goto end;
+ }
+ }
+
+end:
+ if (deleted_ep) {
+ *out_bh = deleted_bh;
+ *out_dentry = deleted_ep;
+ memset((*out_dentry), 0, sizeof(struct exfat_dentry));
+ (*out_dentry)->type = EXFAT_VOLUME;
+ return 0;
+ }
+
+ *out_bh = NULL;
+ *out_dentry = NULL;
+ return ret;
+}
+
+static int exfat_alloc_volume_label(struct super_block *sb)
+{
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+ if (sbi->volume_label)
+ return 0;
+
+ sbi->volume_label = kcalloc(EXFAT_VOLUME_LABEL_LEN,
+ sizeof(short), GFP_KERNEL);
+ if (!sbi->volume_label)
+ return -ENOMEM;
+
+ return 0;
+}
+
+int exfat_read_volume_label(struct super_block *sb)
+{
+ int ret, i;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+ struct buffer_head *bh;
+ struct exfat_dentry *ep;
+
+ ret = exfat_get_volume_label_ptrs(sb, &bh, &ep, false);
+ // ENOENT signifies that a volume label dentry, doesn't exist
+ // We will treat this as an empty volume label and not fail.
+ if (ret < 0 && ret != -ENOENT)
+ goto cleanup;
+
+ ret = exfat_alloc_volume_label(sb);
+ if (ret < 0)
+ goto cleanup;
+
+ mutex_lock(&sbi->s_lock);
+ for (i = 0; i < EXFAT_VOLUME_LABEL_LEN; i++)
+ sbi->volume_label[i] = le16_to_cpu(ep->dentry.volume_label.volume_label[i]);
+ mutex_unlock(&sbi->s_lock);
+
+ ret = 0;
+
+cleanup:
+ if (bh)
+ brelse(bh);
+
+ return ret;
+}
+
+int exfat_write_volume_label(struct super_block *sb,
+ struct exfat_uni_name *uniname)
+{
+ int ret, i;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+ struct buffer_head *bh;
+ struct exfat_dentry *ep;
+
+ if (uniname->name_len > EXFAT_VOLUME_LABEL_LEN) {
+ ret = -EINVAL;
+ goto cleanup;
+ }
+
+ ret = exfat_get_volume_label_ptrs(sb, &bh, &ep, true);
+ if (ret < 0)
+ goto cleanup;
+
+ ret = exfat_alloc_volume_label(sb);
+ if (ret < 0)
+ goto cleanup;
+
+ memcpy(sbi->volume_label, uniname->name,
+ uniname->name_len * sizeof(short));
+
+ mutex_lock(&sbi->s_lock);
+ for (i = 0; i < uniname->name_len; i++)
+ ep->dentry.volume_label.volume_label[i] =
+ cpu_to_le16(sbi->volume_label[i]);
+ // Fill the rest of the str with 0x0000
+ for (; i < EXFAT_VOLUME_LABEL_LEN; i++)
+ ep->dentry.volume_label.volume_label[i] = 0x0000;
+
+ ep->dentry.volume_label.char_count = uniname->name_len;
+ mutex_unlock(&sbi->s_lock);
+
+ ret = 0;
+
+cleanup:
+ if (bh) {
+ exfat_update_bh(bh, true);
+ brelse(bh);
+ }
+
+ return ret;
+}
+
/* mount the file system volume */
static int __exfat_fill_super(struct super_block *sb,
struct exfat_chain *root_clu)
@@ -791,6 +980,7 @@ static void delayed_free(struct rcu_head *p)
unload_nls(sbi->nls_io);
exfat_free_upcase_table(sbi);
+ kfree(sbi->volume_label);
exfat_free_sbi(sbi);
}
--
2.34.1
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