Btrfs: cleanup unused arguments of btrfs_csum_data

Argument 'root' is no more used in btrfs_csum_data().

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 85e072b..3d29d60 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1336,7 +1336,6 @@
 	int page_num;
 	u8 calculated_csum[BTRFS_CSUM_SIZE];
 	u32 crc = ~(u32)0;
-	struct btrfs_root *root = fs_info->extent_root;
 	void *mapped_buffer;
 
 	WARN_ON(!sblock->pagev[0]->page);
@@ -1365,12 +1364,11 @@
 
 	for (page_num = 0;;) {
 		if (page_num == 0 && is_metadata)
-			crc = btrfs_csum_data(root,
+			crc = btrfs_csum_data(
 				((u8 *)mapped_buffer) + BTRFS_CSUM_SIZE,
 				crc, PAGE_SIZE - BTRFS_CSUM_SIZE);
 		else
-			crc = btrfs_csum_data(root, mapped_buffer, crc,
-					      PAGE_SIZE);
+			crc = btrfs_csum_data(mapped_buffer, crc, PAGE_SIZE);
 
 		kunmap_atomic(mapped_buffer);
 		page_num++;
@@ -1657,7 +1655,6 @@
 	void *buffer;
 	u32 crc = ~(u32)0;
 	int fail = 0;
-	struct btrfs_root *root = sctx->dev_root;
 	u64 len;
 	int index;
 
@@ -1674,7 +1671,7 @@
 	for (;;) {
 		u64 l = min_t(u64, len, PAGE_SIZE);
 
-		crc = btrfs_csum_data(root, buffer, crc, l);
+		crc = btrfs_csum_data(buffer, crc, l);
 		kunmap_atomic(buffer);
 		len -= l;
 		if (len == 0)
@@ -1744,7 +1741,7 @@
 	for (;;) {
 		u64 l = min_t(u64, len, mapped_size);
 
-		crc = btrfs_csum_data(root, p, crc, l);
+		crc = btrfs_csum_data(p, crc, l);
 		kunmap_atomic(mapped_buffer);
 		len -= l;
 		if (len == 0)
@@ -1805,7 +1802,7 @@
 	for (;;) {
 		u64 l = min_t(u64, len, mapped_size);
 
-		crc = btrfs_csum_data(root, p, crc, l);
+		crc = btrfs_csum_data(p, crc, l);
 		kunmap_atomic(mapped_buffer);
 		len -= l;
 		if (len == 0)