Modify the subvol and snapshot creation ioctls to work anywhere in the tree

This changes the snapshot and subvol ioctl API and command lines so
that new snapshots and subvols can be created anywhere.

Subvolume creation hasn't changed much:

btrfsctl -S subvol_name directory

This creates a new subvolume under 'directory'

Snapshot creation looks the same, but is actually different:

btrfsctl -s full_path_to_new_snapshot file_or_dir

For example: btrfsctl -s /mnt/new_snap /mnt/subvol

Will create a new snapshot named new_snap under /mnt of the root
found in /mnt/subvol.  It always snapshots the entire root regardless of
which file or directory inside the root you give it.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/ioctl.h b/ioctl.h
index 85ed35a7..5fb2ad18 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -18,13 +18,15 @@
 
 #ifndef __IOCTL_
 #define __IOCTL_
+#include <asm/types.h>
 #include <linux/ioctl.h>
 
 #define BTRFS_IOCTL_MAGIC 0x94
 #define BTRFS_VOL_NAME_MAX 255
-#define BTRFS_PATH_NAME_MAX 4095
+#define BTRFS_PATH_NAME_MAX 3072
 
 struct btrfs_ioctl_vol_args {
+	__s64 fd;
 	char name[BTRFS_PATH_NAME_MAX + 1];
 };
 
@@ -51,5 +53,7 @@ struct btrfs_ioctl_vol_args {
 				   struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_BALANCE _IOW(BTRFS_IOCTL_MAGIC, 12, \
 				   struct btrfs_ioctl_vol_args)
-
+/* 13 is for CLONE_RANGE */
+#define BTRFS_IOC_SUBVOL_CREATE _IOW(BTRFS_IOCTL_MAGIC, 14, \
+				   struct btrfs_ioctl_vol_args)
 #endif