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Wed, 03 Sep 2025 11:33:30 -0700 (PDT) From: Ethan Ferguson To: linkinjeon@kernel.org, sj1557.seo@samsung.com, yuezhang.mo@sony.com Cc: cpgs@samsung.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Ethan Ferguson Subject: [PATCH v5 1/1] exfat: Add support for FS_IOC_{GET,SET}FSLABEL Date: Wed, 3 Sep 2025 14:33:22 -0400 Message-Id: <20250903183322.191136-2-ethan.ferguson@zetier.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250903183322.191136-1-ethan.ferguson@zetier.com> References: <20250903183322.191136-1-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 --- fs/exfat/exfat_fs.h | 7 ++ fs/exfat/exfat_raw.h | 6 ++ fs/exfat/file.c | 80 +++++++++++++++++++++ fs/exfat/namei.c | 2 +- fs/exfat/super.c | 165 +++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 259 insertions(+), 1 deletion(-) diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h index f8ead4d47ef0..a11a086c9d09 100644 --- a/fs/exfat/exfat_fs.h +++ b/fs/exfat/exfat_fs.h @@ -431,6 +431,10 @@ static inline loff_t exfat_ondisk_size(const struct in= ode *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, + struct exfat_uni_name *label_out); +int exfat_write_volume_label(struct super_block *sb, + struct exfat_uni_name *label); =20 /* fatent.c */ #define exfat_get_next_cluster(sb, pclu) exfat_ent_get(sb, *(pclu), pclu) @@ -477,6 +481,9 @@ int exfat_force_shutdown(struct super_block *sb, u32 fl= ags); /* namei.c */ extern const struct dentry_operations exfat_dentry_ops; extern const struct dentry_operations exfat_utf8_dentry_ops; +int exfat_find_empty_entry(struct inode *inode, + struct exfat_chain *p_dir, int num_entries, + struct exfat_entry_set_cache *es); =20 /* cache.c */ int exfat_cache_init(void); 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..c44928c02474 100644 --- a/fs/exfat/file.c +++ b/fs/exfat/file.c @@ -486,6 +486,82 @@ 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; + + uniname =3D kmalloc(sizeof(struct exfat_uni_name), GFP_KERNEL); + if (!uniname) + return -ENOMEM; + + ret =3D exfat_read_volume_label(sb, uniname); + if (ret < 0) + goto cleanup; + + ret =3D exfat_utf16_to_nls(sb, uniname, utf8, FSLABEL_MAX); + if (ret < 0) + goto cleanup; + + if (copy_to_user((char __user *)arg, utf8, FSLABEL_MAX)) { + ret =3D -EFAULT; + goto cleanup; + } + + ret =3D 0; + +cleanup: + kfree(uniname); + return ret; +} + +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 =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]) { + ret =3D exfat_nls_to_utf16(sb, utf8, strnlen(utf8, FSLABEL_MAX), + uniname, &lossy); + if (ret < 0) { + goto cleanup; + } else 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; + uniname->name[EXFAT_VOLUME_LABEL_LEN] =3D 0x0000; + } + + 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 +576,10 @@ 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/namei.c b/fs/exfat/namei.c index f5f1c4e8a29f..eaa781d6263c 100644 --- a/fs/exfat/namei.c +++ b/fs/exfat/namei.c @@ -300,7 +300,7 @@ static int exfat_check_max_dentries(struct inode *inode) * the directory entry index in p_dir is returned on succeeds * -error code is returned on failure */ -static int exfat_find_empty_entry(struct inode *inode, +int exfat_find_empty_entry(struct inode *inode, struct exfat_chain *p_dir, int num_entries, struct exfat_entry_set_cache *es) { diff --git a/fs/exfat/super.c b/fs/exfat/super.c index 8926e63f5bb7..0374e41b48a5 100644 --- a/fs/exfat/super.c +++ b/fs/exfat/super.c @@ -573,6 +573,171 @@ 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 create) +{ + int i, ret; + unsigned int type; + struct exfat_sb_info *sbi =3D EXFAT_SB(sb); + struct inode *root_inode =3D sb->s_root->d_inode; + struct exfat_inode_info *ei =3D EXFAT_I(root_inode); + struct exfat_entry_set_cache es; + struct exfat_chain clu; + struct exfat_dentry *ep, *overwrite_ep =3D NULL; + struct buffer_head *bh, *overwrite_bh =3D NULL; + + 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 error; + } + + type =3D exfat_get_entry_type(ep); + if ((type =3D=3D TYPE_DELETED || type =3D=3D TYPE_UNUSED) + && !overwrite_ep && create) { + overwrite_ep =3D ep; + overwrite_bh =3D bh; + continue; + } + + if (type =3D=3D TYPE_VOLUME) { + *out_bh =3D bh; + *out_dentry =3D ep; + + brelse(overwrite_bh); + return 0; + } + + brelse(bh); + } + + if (exfat_get_next_cluster(sb, &(clu.dir))) { + ret =3D -EIO; + goto error; + } + } + + if (!create) { + ret =3D -ENOENT; + goto error; + } + + + if (overwrite_ep) { + ep =3D overwrite_ep; + bh =3D overwrite_bh; + goto overwrite; + } + + ret =3D exfat_find_empty_entry(root_inode, &clu, 1, &es); + if (ret < 0) + goto error; + + ei->hint_femp.eidx =3D 0; + ei->hint_femp.count =3D sbi->dentries_per_clu; + ei->hint_femp.cur =3D clu; + + ep =3D exfat_get_dentry_cached(&es, 0); + bh =3D es.bh[EXFAT_B_TO_BLK(es.start_off, sb)]; + /* increment use counter so exfat_put_dentry_set doesn't free */ + get_bh(bh); + ret =3D exfat_put_dentry_set(&es, false); + if (ret < 0) { + bforget(bh); + goto error; + } + ei->hint_femp.eidx++; + ei->hint_femp.count--; + +overwrite: + + memset(ep, 0, sizeof(struct exfat_dentry)); + ep->type =3D EXFAT_VOLUME; + *out_bh =3D bh; + *out_dentry =3D ep; + return 0; + +error: + *out_bh =3D NULL; + *out_dentry =3D NULL; + return ret; +} + +int exfat_read_volume_label(struct super_block *sb, struct exfat_uni_name = *label_out) +{ + int ret, i; + struct exfat_sb_info *sbi =3D EXFAT_SB(sb); + struct buffer_head *bh =3D NULL; + struct exfat_dentry *ep =3D NULL; + + mutex_lock(&sbi->s_lock); + + 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 =3D=3D -ENOENT) { + label_out->name[0] =3D 0x0000; + label_out->name_len =3D 0; + ret =3D 0; + } else if (ret < 0) { + goto cleanup; + } else { + for (i =3D 0; i < EXFAT_VOLUME_LABEL_LEN; i++) + label_out->name[i] =3D le16_to_cpu(ep->dentry.volume_label.volume_label= [i]); + label_out->name_len =3D ep->dentry.volume_label.char_count; + } + +cleanup: + mutex_unlock(&sbi->s_lock); + brelse(bh); + return ret; +} + +int exfat_write_volume_label(struct super_block *sb, + struct exfat_uni_name *label) +{ + int ret, i; + struct exfat_sb_info *sbi =3D EXFAT_SB(sb); + struct buffer_head *bh =3D NULL; + struct exfat_dentry *ep =3D NULL; + + if (label->name_len > EXFAT_VOLUME_LABEL_LEN) + return -EINVAL; + + mutex_lock(&sbi->s_lock); + + ret =3D exfat_get_volume_label_ptrs(sb, &bh, &ep, true); + if (ret < 0) + goto cleanup; + + for (i =3D 0; i < label->name_len; i++) + ep->dentry.volume_label.volume_label[i] =3D + cpu_to_le16(label->name[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 label->name_len; + +cleanup: + mutex_unlock(&sbi->s_lock); + + if (bh) { + exfat_update_bh(bh, IS_DIRSYNC(sb->s_root->d_inode)); + brelse(bh); + } + + return ret; +} + /* mount the file system volume */ static int __exfat_fill_super(struct super_block *sb, struct exfat_chain *root_clu) --=20 2.34.1