btrfs: offline dedupe
This patch adds an ioctl, BTRFS_IOC_FILE_EXTENT_SAME which will try to
de-duplicate a list of extents across a range of files.
Internally, the ioctl re-uses code from the clone ioctl. This avoids
rewriting a large chunk of extent handling code.
Userspace passes in an array of file, offset pairs along with a length
argument. The ioctl will then (for each dedupe) do a byte-by-byte comparison
of the user data before deduping the extent. Status and number of bytes
deduped are returned for each operation.
Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Reviewed-by: Zach Brown <zab@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 05aed70..90d7bd9 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -305,6 +305,31 @@
#define BTRFS_DEFRAG_RANGE_COMPRESS 1
#define BTRFS_DEFRAG_RANGE_START_IO 2
+#define BTRFS_SAME_DATA_DIFFERS 1
+/* For extent-same ioctl */
+struct btrfs_ioctl_same_extent_info {
+ __s64 fd; /* in - destination file */
+ __u64 logical_offset; /* in - start of extent in destination */
+ __u64 bytes_deduped; /* out - total # of bytes we were able
+ * to dedupe from this file */
+ /* status of this dedupe operation:
+ * 0 if dedup succeeds
+ * < 0 for error
+ * == BTRFS_SAME_DATA_DIFFERS if data differs
+ */
+ __s32 status; /* out - see above description */
+ __u32 reserved;
+};
+
+struct btrfs_ioctl_same_args {
+ __u64 logical_offset; /* in - start of extent in source */
+ __u64 length; /* in - length of extent */
+ __u16 dest_count; /* in - total elements in info array */
+ __u16 reserved1;
+ __u32 reserved2;
+ struct btrfs_ioctl_same_extent_info info[0];
+};
+
struct btrfs_ioctl_space_info {
__u64 flags;
__u64 total_bytes;
@@ -579,4 +604,7 @@
struct btrfs_ioctl_get_dev_stats)
#define BTRFS_IOC_DEV_REPLACE _IOWR(BTRFS_IOCTL_MAGIC, 53, \
struct btrfs_ioctl_dev_replace_args)
+#define BTRFS_IOC_FILE_EXTENT_SAME _IOWR(BTRFS_IOCTL_MAGIC, 54, \
+ struct btrfs_ioctl_same_args)
+
#endif /* _UAPI_LINUX_BTRFS_H */