Btrfs: add new defrag-range ioctl.

The btrfs defrag ioctl was limited to doing the entire file.  This
commit adds a new interface that can defrag a specific range inside
the file.

It can also force compression on the file, allowing you to selectively
compress individual files after they were created, even when mount -o
compress isn't turned on.

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

1 files changed, 31 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index f1923e0260e3..2d64a65842f3 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -99,6 +99,35 @@ struct btrfs_ioctl_clone_range_args {
   __u64 dest_offset;
 };
 
+/* flags for the defrag range ioctl */
+#define BTRFS_DEFRAG_RANGE_COMPRESS 1
+#define BTRFS_DEFRAG_RANGE_START_IO 2
+
+struct btrfs_ioctl_defrag_range_args {
+        /* start of the defrag operation */
+        __u64 start;
+
+        /* number of bytes to defrag, use (u64)-1 to say all */
+        __u64 len;
+
+        /*
+         * flags for the operation, which can include turning
+         * on compression for this one defrag
+         */
+        __u64 flags;
+
+        /*
+         * any extent bigger than this will be considered
+         * already defragged.  Use 0 to take the kernel default
+         * Use 1 to say every single extent must be rewritten
+         */
+        __u32 extent_thresh;
+
+        /* spare for later */
+        __u32 unused[5];
+};
+
+
 #define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \
                                    struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_DEFRAG _IOW(BTRFS_IOCTL_MAGIC, 2, \
@@ -130,6 +159,8 @@ struct btrfs_ioctl_clone_range_args {
                                    struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_SNAP_DESTROY _IOW(BTRFS_IOCTL_MAGIC, 15, \
                                 struct btrfs_ioctl_vol_args)
+#define BTRFS_IOC_DEFRAG_RANGE _IOW(BTRFS_IOCTL_MAGIC, 16, \
+                                struct btrfs_ioctl_defrag_range_args)
 #define BTRFS_IOC_TREE_SEARCH _IOWR(BTRFS_IOCTL_MAGIC, 17, \
                                    struct btrfs_ioctl_search_args)
 #define BTRFS_IOC_INO_LOOKUP _IOWR(BTRFS_IOCTL_MAGIC, 18, \