btrfs: added helper functions to iterate backrefs

These helper functions iterate back references and call a function for each
backref. There is also a function to resolve an inode to a path in the
file system.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

1 files changed, 11 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index ad1ea789fcb4..1857e3871843 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -193,6 +193,17 @@ struct btrfs_ioctl_space_args {
         struct btrfs_ioctl_space_info spaces[0];
 };
 
+struct btrfs_data_container {
+        __u32   bytes_left;     /* out -- bytes not needed to deliver output */
+        __u32   bytes_missing;  /* out -- additional bytes needed for result */
+        __u32   elem_cnt;       /* out */
+        __u32   elem_missed;    /* out */
+        union {
+                char    *str[0];        /* out */
+                __u64   val[0];         /* out */
+        };
+};
+
 #define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
                                    struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \