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Thu, 21 Aug 2025 08:09:36 -0700 (PDT) From: Ethan Ferguson To: linkinjeon@kernel.org, sj1557.seo@samsung.com, yuezhang.mo@sony.com Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Ethan Ferguson Subject: [PATCH v3 1/1] exfat: Add support for FS_IOC_{GET,SET}FSLABEL Date: Thu, 21 Aug 2025 11:09:26 -0400 Message-Id: <20250821150926.1025302-2-ethan.ferguson@zetier.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250821150926.1025302-1-ethan.ferguson@zetier.com> References: <20250821150926.1025302-1-ethan.ferguson@zetier.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 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 */ =20 unsigned short *vol_utbl; /* upcase table */ + unsigned short *volume_label; /* volume name */ =20 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 ino= de *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); =20 /* 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 =20 #define EXFAT_FILE_NAME_LEN 15 +#define EXFAT_VOLUME_LABEL_LEN 11 =20 #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 #include #include +#include "../nls/nls_ucs2_utils.h" =20 #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); } =20 +static int exfat_ioctl_get_volume_label(struct super_block *sb, unsigned l= ong arg) +{ + int ret; + char utf8[FSLABEL_MAX] =3D {0}; + struct exfat_uni_name *uniname; + struct exfat_sb_info *sbi =3D EXFAT_SB(sb); + + uniname =3D kmalloc(sizeof(struct exfat_uni_name), GFP_KERNEL); + if (!uniname) + return -ENOMEM; + + ret =3D 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] =3D 0x0000; + uniname->name_len =3D UniStrnlen(uniname->name, EXFAT_VOLUME_LABEL_LEN); + + ret =3D exfat_utf16_to_nls(sb, uniname, utf8, FSLABEL_MAX); + + if (copy_to_user((char __user *)arg, utf8, FSLABEL_MAX)) { + ret =3D -EFAULT; + goto cleanup; + } + +cleanup: + kfree(uniname); + return 0; +} + +static int exfat_ioctl_set_volume_label(struct super_block *sb, unsigned l= ong arg) +{ + int ret, lossy; + char utf8[FSLABEL_MAX]; + struct exfat_uni_name *uniname; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + uniname =3D kmalloc(sizeof(struct exfat_uni_name), GFP_KERNEL); + if (!uniname) + return -ENOMEM; + + if (copy_from_user(utf8, (char __user *)arg, FSLABEL_MAX)) { + ret =3D -EFAULT; + goto cleanup; + } + + if (utf8[0]) { + exfat_nls_to_utf16(sb, utf8, strnlen(utf8, FSLABEL_MAX), uniname, &lossy= ); + if (lossy & NLS_NAME_LOSSY) { + ret =3D -EINVAL; + goto cleanup; + } + } else { + uniname->name[0] =3D 0x0000; + uniname->name_len =3D 0; + } + + if (uniname->name_len > EXFAT_VOLUME_LABEL_LEN) { + exfat_info(sb, "Volume label length too long, truncating"); + uniname->name_len =3D EXFAT_VOLUME_LABEL_LEN; + } + + ret =3D 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 =3D 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 #include #include +#include "../nls/nls_ucs2_utils.h" =20 #include "exfat_raw.h" #include "exfat_fs.h" @@ -573,6 +574,194 @@ static int exfat_verify_boot_region(struct super_bloc= k *sb) return 0; } =20 +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 =3D EXFAT_SB(sb); + struct exfat_chain clu; + struct exfat_dentry *ep, *deleted_ep =3D NULL; + struct buffer_head *bh, *deleted_bh; + + clu.dir =3D sbi->root_dir; + clu.flags =3D ALLOC_FAT_CHAIN; + + while (clu.dir !=3D EXFAT_EOF_CLUSTER) { + for (i =3D 0; i < sbi->dentries_per_clu; i++) { + ep =3D exfat_get_dentry(sb, &clu, i, &bh); + + if (!ep) { + ret =3D -EIO; + goto end; + } + + type =3D exfat_get_entry_type(ep); + if (type =3D=3D TYPE_DELETED && !deleted_ep && find_new) { + deleted_ep =3D ep; + deleted_bh =3D bh; + continue; + } + + if (type =3D=3D TYPE_UNUSED) { + if (find_new) { + brelse(bh); + ret =3D -ENOENT; + goto end; + } + + if (deleted_ep) { + brelse(bh); + goto end; + } + + // Last dentry in cluster + if (i =3D=3D sbi->dentries_per_clu - 1) { + // TODO allocate new cluster + brelse(bh); + ret =3D -ENOSPC; + goto end; + } + + deleted_ep =3D ep; + deleted_bh =3D bh; + + ep =3D exfat_get_dentry(sb, &clu, i + 1, &bh); + memset(ep, 0, sizeof(struct exfat_dentry)); + ep->type =3D EXFAT_UNUSED; + exfat_update_bh(bh, true); + brelse(bh); + + goto end; + } + + if (type =3D=3D TYPE_VOLUME) { + *out_bh =3D bh; + *out_dentry =3D ep; + + if (deleted_ep) + brelse(deleted_bh); + + return 0; + } + + brelse(bh); + } + + if (exfat_get_next_cluster(sb, &(clu.dir))) { + ret =3D -EIO; + goto end; + } + } + +end: + if (deleted_ep) { + *out_bh =3D deleted_bh; + *out_dentry =3D deleted_ep; + memset((*out_dentry), 0, sizeof(struct exfat_dentry)); + (*out_dentry)->type =3D EXFAT_VOLUME; + return 0; + } + + *out_bh =3D NULL; + *out_dentry =3D NULL; + return ret; +} + +static int exfat_alloc_volume_label(struct super_block *sb) +{ + struct exfat_sb_info *sbi =3D EXFAT_SB(sb); + + if (sbi->volume_label) + return 0; + + sbi->volume_label =3D 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 =3D EXFAT_SB(sb); + struct buffer_head *bh; + struct exfat_dentry *ep; + + ret =3D 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 !=3D -ENOENT) + goto cleanup; + + ret =3D exfat_alloc_volume_label(sb); + if (ret < 0) + goto cleanup; + + mutex_lock(&sbi->s_lock); + for (i =3D 0; i < EXFAT_VOLUME_LABEL_LEN; i++) + sbi->volume_label[i] =3D le16_to_cpu(ep->dentry.volume_label.volume_labe= l[i]); + mutex_unlock(&sbi->s_lock); + + ret =3D 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 =3D EXFAT_SB(sb); + struct buffer_head *bh; + struct exfat_dentry *ep; + + if (uniname->name_len > EXFAT_VOLUME_LABEL_LEN) { + ret =3D -EINVAL; + goto cleanup; + } + + ret =3D exfat_get_volume_label_ptrs(sb, &bh, &ep, true); + if (ret < 0) + goto cleanup; + + ret =3D 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 =3D 0; i < uniname->name_len; i++) + ep->dentry.volume_label.volume_label[i] =3D + 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] =3D 0x0000; + + ep->dentry.volume_label.char_count =3D uniname->name_len; + mutex_unlock(&sbi->s_lock); + + ret =3D 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) =20 unload_nls(sbi->nls_io); exfat_free_upcase_table(sbi); + kfree(sbi->volume_label); exfat_free_sbi(sbi); } =20 --=20 2.34.1