From 41bcbe59c3b3fa7171dd2e3a365e6d5154198f30 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Tue, 6 Feb 2024 21:56:17 -0500 Subject: fs: FS_IOC_GETUUID Add a new generic ioctls for querying the filesystem UUID. These are lifted versions of the ext4 ioctls, with one change: we're not using a flexible array member, because UUIDs will never be more than 16 bytes. This patch adds a generic implementation of FS_IOC_GETFSUUID, which reads from super_block->s_uuid. We're not lifting SETFSUUID from ext4 - that can be done on offline filesystems by the people who need it, trying to do it online is just asking for too much trouble. Cc: Christian Brauner Cc: Jan Kara Cc: Dave Chinner Cc: Darrick J. Wong Cc: Theodore Ts'o Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Kent Overstreet Link: https://lore.kernel.org/r/20240207025624.1019754-4-kent.overstreet@linux.dev Signed-off-by: Christian Brauner --- include/uapi/linux/fs.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/uapi') diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 48ad69f7722e..40880ce99d02 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 fsuuid2 { + __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 +228,8 @@ 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]) +/* Returns the external filesystem UUID, the same one blkid returns */ +#define FS_IOC_GETFSUUID _IOR(0x15, 0, struct fsuuid2) /* * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS) -- cgit v1.2.3 From ae8c511757304e0c393661b5ed2ad7073e2a351d Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Tue, 6 Feb 2024 21:56:19 -0500 Subject: fs: add FS_IOC_GETFSSYSFSPATH Add a new ioctl for getting the sysfs name of a filesystem - the path under /sys/fs. This is going to let us standardize exporting data from sysfs across filesystems, e.g. time stats. The returned path will always be of the form "$FSTYP/$SYSFS_IDENTIFIER", where the sysfs identifier may be a UUID (for bcachefs) or a device name (xfs). Cc: Christian Brauner Cc: Jan Kara Cc: Dave Chinner Cc: Darrick J. Wong Cc: Theodore Ts'o Cc: Josef Bacik Signed-off-by: Kent Overstreet Link: https://lore.kernel.org/r/20240207025624.1019754-6-kent.overstreet@linux.dev Signed-off-by: Christian Brauner --- fs/ioctl.c | 17 +++++++++++++++++ include/linux/fs.h | 43 +++++++++++++++++++++++++++++++++++++++++++ include/uapi/linux/fs.h | 10 ++++++++++ 3 files changed, 70 insertions(+) (limited to 'include/uapi') diff --git a/fs/ioctl.c b/fs/ioctl.c index 74eab9549383..1d5abfdf0f22 100644 --- a/fs/ioctl.c +++ b/fs/ioctl.c @@ -776,6 +776,20 @@ static int ioctl_getfsuuid(struct file *file, void __user *argp) return copy_to_user(argp, &u, sizeof(u)) ? -EFAULT : 0; } +static int ioctl_get_fs_sysfs_path(struct file *file, void __user *argp) +{ + struct super_block *sb = file_inode(file)->i_sb; + + if (!strlen(sb->s_sysfs_name)) + return -ENOIOCTLCMD; + + struct fs_sysfs_path u = {}; + + u.len = scnprintf(u.name, sizeof(u.name), "%s/%s", sb->s_type->name, sb->s_sysfs_name); + + 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. @@ -861,6 +875,9 @@ static int do_vfs_ioctl(struct file *filp, unsigned int fd, case FS_IOC_GETFSUUID: return ioctl_getfsuuid(filp, argp); + case FS_IOC_GETFSSYSFSPATH: + return ioctl_get_fs_sysfs_path(filp, argp); + default: if (S_ISREG(inode->i_mode)) return file_ioctl(filp, cmd, argp); diff --git a/include/linux/fs.h b/include/linux/fs.h index acdc56987cb1..c6d9e1b7032c 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1255,10 +1255,23 @@ struct super_block { struct fsnotify_mark_connector __rcu *s_fsnotify_marks; #endif + /* + * q: why are s_id and s_sysfs_name not the same? both are human + * readable strings that identify the filesystem + * a: s_id is allowed to change at runtime; it's used in log messages, + * and we want to when a device starts out as single device (s_id is dev + * name) but then a device is hot added and we have to switch to + * identifying it by UUID + * but s_sysfs_name is a handle for programmatic access, and can't + * change at runtime + */ char s_id[32]; /* Informational name */ uuid_t s_uuid; /* UUID */ u8 s_uuid_len; /* Default 16, possibly smaller for weird filesystems */ + /* if set, fs shows up under sysfs at /sys/fs/$FSTYP/s_sysfs_name */ + char s_sysfs_name[UUID_STRING_LEN + 1]; + unsigned int s_max_links; /* @@ -2541,6 +2554,36 @@ static inline void super_set_uuid(struct super_block *sb, const u8 *uuid, unsign memcpy(&sb->s_uuid, uuid, len); } +/* set sb sysfs name based on sb->s_bdev */ +static inline void super_set_sysfs_name_bdev(struct super_block *sb) +{ + snprintf(sb->s_sysfs_name, sizeof(sb->s_sysfs_name), "%pg", sb->s_bdev); +} + +/* set sb sysfs name based on sb->s_uuid */ +static inline void super_set_sysfs_name_uuid(struct super_block *sb) +{ + WARN_ON(sb->s_uuid_len != sizeof(sb->s_uuid)); + snprintf(sb->s_sysfs_name, sizeof(sb->s_sysfs_name), "%pU", sb->s_uuid.b); +} + +/* set sb sysfs name based on sb->s_id */ +static inline void super_set_sysfs_name_id(struct super_block *sb) +{ + strscpy(sb->s_sysfs_name, sb->s_id, sizeof(sb->s_sysfs_name)); +} + +/* try to use something standard before you use this */ +__printf(2, 3) +static inline void super_set_sysfs_name_generic(struct super_block *sb, const char *fmt, ...) +{ + va_list args; + + va_start(args, fmt); + vsnprintf(sb->s_sysfs_name, sizeof(sb->s_sysfs_name), fmt, args); + va_end(args); +} + extern int current_umask(void); extern void ihold(struct inode * inode); diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 40880ce99d02..dcd6c8c7d2c7 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -77,6 +77,11 @@ struct fsuuid2 { __u8 uuid[16]; }; +struct fs_sysfs_path { + __u8 len; + __u8 name[128]; +}; + /* extent-same (dedupe) ioctls; these MUST match the btrfs ioctl definitions */ #define FILE_DEDUPE_RANGE_SAME 0 #define FILE_DEDUPE_RANGE_DIFFERS 1 @@ -230,6 +235,11 @@ struct fsxattr { #define FS_IOC_SETFSLABEL _IOW(0x94, 50, char[FSLABEL_MAX]) /* Returns the external filesystem UUID, the same one blkid returns */ #define FS_IOC_GETFSUUID _IOR(0x15, 0, struct fsuuid2) +/* + * Returns the path component under /sys/fs/ that refers to this filesystem; + * also /sys/kernel/debug/ for filesystems with debugfs exports + */ +#define FS_IOC_GETFSSYSFSPATH _IOR(0x15, 1, struct fs_sysfs_path) /* * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS) -- cgit v1.2.3