diff options
| author | Kent Overstreet <kent.overstreet@linux.dev> | 2024-02-03 15:27:13 -0500 |
|---|---|---|
| committer | Kent Overstreet <kent.overstreet@linux.dev> | 2024-02-03 15:43:38 -0500 |
| commit | 350bc16072dd78f02cbb37575eb54afa9ec8ce18 (patch) | |
| tree | 72e4bd59baef0cf99ada93ed090b0a2ab39986e2 | |
| parent | 174fc78e24a34bbd8a3943b847fe6cf74089373e (diff) | |
fs: FS_IOC_GETUUID
Add a new generic ioctls for querying the filesystem UUID.
'struct fsuuid' has a length field, so that these can be used for old
weird filesystems without a real UUID (vfat). The length must never
be more than 16 bytes.
This patch adds a generic implementation of FS_IOC_GETFSUUID, which
reads from super_block->s_uuid.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Alexander Viro <viro@zeniv.linux.org.uk
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: linux-fsdevel@vger.kernel.or
| -rw-r--r-- | fs/ioctl.c | 16 | ||||
| -rw-r--r-- | include/uapi/linux/fs.h | 14 |
2 files changed, 30 insertions, 0 deletions
diff --git a/fs/ioctl.c b/fs/ioctl.c index 76cf22ac97d7..504e661d0330 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -763,6 +763,19 @@ static int ioctl_fssetxattr(struct file *file, void __user *argp) return err; } +static int ioctl_getfsuuid(struct file *file, void __user *argp) +{ + struct super_block *sb = file_inode(file)->i_sb; + + if (WARN_ON(sb->s_uuid_len > sizeof(sb->s_uuid))) + sb->s_uuid_len = sizeof(sb->s_uuid); + + struct fsuuid u = { .len = sb->s_uuid_len, }; + memcpy(&u.uuid[0], &sb->s_uuid, sb->s_uuid_len); + + return copy_to_user(argp, &u, sizeof(u)) ? -EFAULT : 0; +} + /* * do_vfs_ioctl() is not for drivers and not intended to be EXPORT_SYMBOL()'d. * It's just a simple helper for sys_ioctl and compat_sys_ioctl. @@ -845,6 +858,9 @@ static int do_vfs_ioctl(struct file *filp, unsigned int fd, case FS_IOC_FSSETXATTR: return ioctl_fssetxattr(filp, argp); + case FS_IOC_GETFSUUID: + return ioctl_getfsuuid(filp, argp); + default: if (S_ISREG(inode->i_mode)) return file_ioctl(filp, cmd, argp); diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 48ad69f7722e..a6e04770ad35 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -64,6 +64,19 @@ struct fstrim_range { __u64 minlen; }; +/* + * We include a length field because some filesystems (vfat) have an identifier + * that we do want to expose as a UUID, but doesn't have the standard length. + * + * We use a fixed size buffer beacuse this interface will, by fiat, never + * support "UUIDs" longer than 16 bytes; we don't want to force all downstream + * users to have to deal with that. + */ +struct fsuuid { + __u8 len; + __u8 uuid[16]; +}; + /* extent-same (dedupe) ioctls; these MUST match the btrfs ioctl definitions */ #define FILE_DEDUPE_RANGE_SAME 0 #define FILE_DEDUPE_RANGE_DIFFERS 1 @@ -215,6 +228,7 @@ struct fsxattr { #define FS_IOC_FSSETXATTR _IOW('X', 32, struct fsxattr) #define FS_IOC_GETFSLABEL _IOR(0x94, 49, char[FSLABEL_MAX]) #define FS_IOC_SETFSLABEL _IOW(0x94, 50, char[FSLABEL_MAX]) +#define FS_IOC_GETFSUUID _IOR(0x94, 51, struct fsuuid) /* * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS) |