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Message-Id: <20250815171056.103751-2-ethan.ferguson@zetier.com>
Date: Fri, 15 Aug 2025 13:10:56 -0400
From: Ethan Ferguson <ethan.ferguson@...ier.com>
To: linkinjeon@...nel.org,
sj1557.seo@...sung.com
Cc: yuezhang.mo@...y.com,
linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org,
Ethan Ferguson <ethan.ferguson@...ier.com>
Subject: [PATCH 1/1] exfat: Add support for FS_IOC_{GET,SET}FSLABEL
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@...ier.com>
---
fs/exfat/exfat_fs.h | 2 +
fs/exfat/exfat_raw.h | 6 +++
fs/exfat/file.c | 56 +++++++++++++++++++++++++
fs/exfat/super.c | 99 ++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 163 insertions(+)
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index f8ead4d47ef0..a764e6362172 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[EXFAT_VOLUME_LABEL_LEN]; /* volume name */
unsigned int clu_srch_ptr; /* cluster search pointer */
unsigned int used_clusters; /* number of used clusters */
@@ -431,6 +432,7 @@ 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_write_volume_label(struct super_block *sb);
/* 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..af04cef81c0c 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;
struct {
__u8 flags;
__u8 vendor_guid[16];
diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index 538d2b6ac2ec..c57d266aae3d 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 +487,57 @@ 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_sb_info *sbi = EXFAT_SB(sb);
+ size_t len = UniStrnlen(sbi->volume_label, EXFAT_VOLUME_LABEL_LEN);
+
+ mutex_lock(&sbi->s_lock);
+ ret = utf16s_to_utf8s(sbi->volume_label, len,
+ UTF16_HOST_ENDIAN, utf8, FSLABEL_MAX);
+ mutex_unlock(&sbi->s_lock);
+
+ if (ret < 0)
+ return ret;
+
+ if (copy_to_user((char __user *)arg, utf8, FSLABEL_MAX))
+ return -EFAULT;
+
+ return 0;
+}
+
+static int exfat_ioctl_set_volume_label(struct super_block *sb, unsigned long arg)
+{
+ int ret = 0;
+ char utf8[FSLABEL_MAX];
+ size_t len;
+ unsigned short utf16[EXFAT_VOLUME_LABEL_LEN] = {0};
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (copy_from_user(utf8, (char __user *)arg, FSLABEL_MAX))
+ return -EFAULT;
+
+ len = strnlen(utf8, FSLABEL_MAX);
+ if (len > EXFAT_VOLUME_LABEL_LEN)
+ exfat_info(sb, "Volume label length too long, truncating");
+
+ mutex_lock(&sbi->s_lock);
+ ret = utf8s_to_utf16s(utf8, len, UTF16_HOST_ENDIAN, utf16, EXFAT_VOLUME_LABEL_LEN);
+ mutex_unlock(&sbi->s_lock);
+
+ if (ret < 0)
+ return ret;
+
+ memcpy(sbi->volume_label, utf16, sizeof(sbi->volume_label));
+
+ return exfat_write_volume_label(sb);
+}
+
long exfat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
@@ -500,6 +552,10 @@ 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..cd426bb332e0 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 +574,98 @@ 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)
+{
+ int i;
+ unsigned int type;
+ struct exfat_sb_info *sbi = EXFAT_SB(sb);
+ struct exfat_chain clu;
+ struct exfat_dentry *ep;
+ struct buffer_head *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)
+ return -EIO;
+
+ type = exfat_get_entry_type(ep);
+ if (type == TYPE_UNUSED) {
+ brelse(bh);
+ return -EIO;
+ }
+
+ if (type == TYPE_VOLUME) {
+ *out_bh = bh;
+ *out_dentry = ep;
+ return 0;
+ }
+
+ brelse(bh);
+ }
+
+ if (exfat_get_next_cluster(sb, &(clu.dir)))
+ return -EIO;
+ }
+
+ return -EIO;
+}
+
+static int exfat_read_volume_label(struct super_block *sb)
+{
+ int ret;
+ 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);
+ if (ret < 0)
+ goto cleanup;
+
+ memcpy(sbi->volume_label, ep->dentry.volume_label.volume_label, sizeof(sbi->volume_label));
+
+cleanup:
+ if (bh)
+ brelse(bh);
+
+ return ret;
+}
+
+int exfat_write_volume_label(struct super_block *sb)
+{
+ int ret;
+ 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);
+ if (ret < 0)
+ goto cleanup;
+
+ mutex_lock(&sbi->s_lock);
+ memcpy(ep->dentry.volume_label.volume_label, sbi->volume_label,
+ sizeof(sbi->volume_label));
+
+ ep->dentry.volume_label.char_count =
+ UniStrnlen(ep->dentry.volume_label.volume_label,
+ EXFAT_VOLUME_LABEL_LEN);
+ mutex_unlock(&sbi->s_lock);
+
+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)
@@ -616,6 +709,12 @@ static int __exfat_fill_super(struct super_block *sb,
goto free_bh;
}
+ ret = exfat_read_volume_label(sb);
+ if (ret) {
+ exfat_err(sb, "failed to read volume label");
+ goto free_bh;
+ }
+
ret = exfat_count_used_clusters(sb, &sbi->used_clusters);
if (ret) {
exfat_err(sb, "failed to scan clusters");
--
2.34.1
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