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[34.21.69.243]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8971cc7f82csm175513186d6.4.2026.02.17.15.08.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Feb 2026 15:08:54 -0800 (PST) From: Ethan Ferguson To: hirofumi@mail.parknet.co.jp Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Ethan Ferguson Subject: [PATCH v2 2/2] fat: Add FS_IOC_SETFSLABEL ioctl Date: Tue, 17 Feb 2026 18:06:28 -0500 Message-ID: <20260217230628.719475-3-ethan.ferguson@zetier.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260217230628.719475-1-ethan.ferguson@zetier.com> References: <20260217230628.719475-1-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 writing to the volume label of a FAT filesystem via the FS_IOC_SETFSLABEL ioctl. Signed-off-by: Ethan Ferguson --- fs/fat/dir.c | 51 +++++++++++++++++++++++++++++++++++ fs/fat/fat.h | 6 +++++ fs/fat/file.c | 63 ++++++++++++++++++++++++++++++++++++++++++++ fs/fat/inode.c | 15 +++++++++++ fs/fat/namei_msdos.c | 4 +-- 5 files changed, 137 insertions(+), 2 deletions(-) diff --git a/fs/fat/dir.c b/fs/fat/dir.c index 07d95f1442c8..1b11713309ae 100644 --- a/fs/fat/dir.c +++ b/fs/fat/dir.c @@ -1425,3 +1425,54 @@ int fat_add_entries(struct inode *dir, void *slots, = int nr_slots, return err; } EXPORT_SYMBOL_GPL(fat_add_entries); + +static int fat_create_volume_label_dentry(struct super_block *sb, char *vo= l_label) +{ + struct msdos_sb_info *sbi =3D MSDOS_SB(sb); + struct inode *root_inode =3D sb->s_root->d_inode; + struct msdos_dir_entry de; + struct fat_slot_info sinfo; + struct timespec64 ts =3D current_time(root_inode); + __le16 date, time; + u8 time_cs; + + memcpy(de.name, vol_label, MSDOS_NAME); + de.attr =3D ATTR_VOLUME; + de.starthi =3D de.start =3D de.size =3D de.lcase =3D 0; + + fat_time_unix2fat(sbi, &ts, &time, &date, &time_cs); + de.time =3D time; + de.date =3D date; + if (sbi->options.isvfat) { + de.cdate =3D de.adate =3D date; + de.ctime =3D time; + de.ctime_cs =3D time_cs; + } else + de.cdate =3D de.adate =3D de.ctime =3D de.ctime_cs =3D 0; + + return fat_add_entries(root_inode, &de, 1, &sinfo); +} + +int fat_rename_volume_label_dentry(struct super_block *sb, char *vol_label) +{ + struct inode *root_inode =3D sb->s_root->d_inode; + struct buffer_head *bh =3D NULL; + struct msdos_dir_entry *de; + loff_t cpos =3D 0; + int err =3D 0; + + while (1) { + if (fat_get_entry(root_inode, &cpos, &bh, &de) =3D=3D -1) + return fat_create_volume_label_dentry(sb, vol_label); + + if (de->attr =3D=3D ATTR_VOLUME) { + memcpy(de->name, vol_label, MSDOS_NAME); + mark_buffer_dirty_inode(bh, root_inode); + if (IS_DIRSYNC(root_inode)) + err =3D sync_dirty_buffer(bh); + brelse(bh); + return err; + } + } +} +EXPORT_SYMBOL_GPL(fat_rename_volume_label_dentry); diff --git a/fs/fat/fat.h b/fs/fat/fat.h index 4350c00dba34..3b75223fbe76 100644 --- a/fs/fat/fat.h +++ b/fs/fat/fat.h @@ -341,6 +341,8 @@ extern int fat_alloc_new_dir(struct inode *dir, struct = timespec64 *ts); extern int fat_add_entries(struct inode *dir, void *slots, int nr_slots, struct fat_slot_info *sinfo); extern int fat_remove_entries(struct inode *dir, struct fat_slot_info *sin= fo); +extern int fat_rename_volume_label_dentry(struct super_block *sb, + char *vol_label); =20 /* fat/fatent.c */ struct fat_entry { @@ -480,6 +482,10 @@ extern int fat_sync_bhs(struct buffer_head **bhs, int = nr_bhs); int fat_cache_init(void); void fat_cache_destroy(void); =20 +/* fat/namei/msdos.c */ +int msdos_format_name(const unsigned char *name, int len, + unsigned char *res, struct fat_mount_options *opts); + /* fat/nfs.c */ extern const struct export_operations fat_export_ops; extern const struct export_operations fat_export_ops_nostale; diff --git a/fs/fat/file.c b/fs/fat/file.c index 029b1750d1ec..5d445c2d8657 100644 --- a/fs/fat/file.c +++ b/fs/fat/file.c @@ -167,6 +167,67 @@ static int fat_ioctl_get_volume_label(struct super_blo= ck *sb, char __user *arg) return 0; } =20 +static int fat_convert_volume_label_str(struct msdos_sb_info *sbi, char *i= n, + char *out) +{ + int ret, in_len =3D max(strnlen(in, FSLABEL_MAX), 11); + char *needle; + + /* + * '.' is not included in any bad_chars list in this driver, + * but it is specifically not allowed for volume labels + */ + for (needle =3D in; needle - in < in_len; needle++) + if (*needle =3D=3D '.') + return -EINVAL; + + ret =3D msdos_format_name(in, in_len, out, &sbi->options); + if (ret) + return ret; + + /* + * msdos_format_name assumes we're translating an 8.3 name, but + * we can handle 11 chars + */ + if (in_len > 8) + ret =3D msdos_format_name(in + 8, in_len - 8, out + 8, + &sbi->options); + return ret; +} + +static int fat_ioctl_set_volume_label(struct super_block *sb, char __user = *arg) +{ + struct msdos_sb_info *sbi =3D MSDOS_SB(sb); + struct inode *root_inode =3D sb->s_root->d_inode; + char from_user[FSLABEL_MAX]; + char new_vol_label[MSDOS_NAME]; + int ret; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (sb_rdonly(sb)) + return -EROFS; + + if (copy_from_user(from_user, arg, FSLABEL_MAX)) + return -EFAULT; + + ret =3D fat_convert_volume_label_str(sbi, from_user, new_vol_label); + if (ret) + return ret; + + inode_lock(root_inode); + ret =3D fat_rename_volume_label_dentry(sb, new_vol_label); + inode_unlock(root_inode); + if (ret) + return ret; + + mutex_lock(&sbi->s_lock); + memcpy(sbi->vol_label, new_vol_label, MSDOS_NAME); + mutex_unlock(&sbi->s_lock); + return 0; +} + long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long = arg) { struct inode *inode =3D file_inode(filp); @@ -181,6 +242,8 @@ long fat_generic_ioctl(struct file *filp, unsigned int = cmd, unsigned long arg) return fat_ioctl_get_volume_id(inode, user_attr); case FS_IOC_GETFSLABEL: return fat_ioctl_get_volume_label(inode->i_sb, (char __user *) arg); + case FS_IOC_SETFSLABEL: + return fat_ioctl_set_volume_label(inode->i_sb, (char __user *) arg); case FITRIM: return fat_ioctl_fitrim(inode, arg); default: diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 6f9a8cc1ad2a..a7528937383b 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -736,6 +736,21 @@ static void delayed_free(struct rcu_head *p) static void fat_put_super(struct super_block *sb) { struct msdos_sb_info *sbi =3D MSDOS_SB(sb); + struct buffer_head *bh =3D NULL; + struct fat_boot_sector *bs; + + bh =3D sb_bread(sb, 0); + if (bh =3D=3D NULL) + fat_msg(sb, KERN_ERR, "unable to read boot sector"); + else if (!sb_rdonly(sb)) { + bs =3D (struct fat_boot_sector *)bh->b_data; + if (is_fat32(sbi)) + memcpy(bs->fat32.vol_label, sbi->vol_label, MSDOS_NAME); + else + memcpy(bs->fat16.vol_label, sbi->vol_label, MSDOS_NAME); + mark_buffer_dirty(bh); + } + brelse(bh); =20 fat_set_state(sb, 0, 0); =20 diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c index ba0152ed0810..92b5d387f88e 100644 --- a/fs/fat/namei_msdos.c +++ b/fs/fat/namei_msdos.c @@ -16,8 +16,8 @@ static unsigned char bad_chars[] =3D "*?<>|\""; static unsigned char bad_if_strict[] =3D "+=3D,; "; =20 /***** Formats an MS-DOS file name. Rejects invalid names. */ -static int msdos_format_name(const unsigned char *name, int len, - unsigned char *res, struct fat_mount_options *opts) +int msdos_format_name(const unsigned char *name, int len, unsigned char *r= es, + struct fat_mount_options *opts) /* * name is the proposed name, len is its length, res is * the resulting name, opts->name_check is either (r)elaxed, --=20 2.43.0