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 <brauner@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Dave Chinner <dchinner@xxxxxxxxxx>
Cc: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Josef Bacik <josef@xxxxxxxxxxxxxx>
Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
---
fs/ioctl.c | 17 +++++++++++++++++
include/linux/fs.h | 1 +
include/uapi/linux/fs.h | 10 ++++++++++
3 files changed, 28 insertions(+)
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 046c30294a82..7c37765bd04e 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 fssysfspath u = {};
+
+ snprintf(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..b96c1d009718 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1258,6 +1258,7 @@ struct super_block {
char s_id[32]; /* Informational name */
uuid_t s_uuid; /* UUID */
u8 s_uuid_len; /* Default 16, possibly smaller for weird filesystems */
+ char s_sysfs_name[UUID_STRING_LEN + 1];
unsigned int s_max_links;
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 16a6ecadfd8d..c0f7bd4b6350 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -77,6 +77,10 @@ struct fsuuid2 {
__u8 uuid[16];
};
+struct fssysfspath {
+ __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
@@ -206,6 +210,12 @@ struct fsxattr {
/* Returns the external filesystem UUID, the same one blkid returns */
#define FS_IOC_GETFSUUID _IOR(0x12, 142, 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(0x12, 143, struct fssysfspath)
+
#define BMAP_IOCTL 1 /* obsolete - kept for compatibility */
#define FIBMAP _IO(0x00,1) /* bmap access */
#define FIGETBSZ _IO(0x00,2) /* get the block size used for bmap */
--
2.43.0
