Btrfs: use fastpath in extent state ops as much as possible

Fully utilize our extent state's new helper functions to use
fastpath as much as possible.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Reviewed-by: Josef Bacik <josef@redhat.com>

fs/btrfs/extent_io.c

@@ -569,10 +569,8 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		if (err)
 			goto out;
 		if (state->end <= end) {
-			clear_state_bit(tree, state, &bits, wake);
-			if (last_end == (u64)-1)
-				goto out;
-			start = last_end + 1;
+			state = clear_state_bit(tree, state, &bits, wake);
+			goto next;
 		}
 		goto search_again;
 	}
@@ -780,7 +778,6 @@ __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	 * Just lock what we found and keep going
 	 */
 	if (state->start == start && state->end <= end) {
-		struct rb_node *next_node;
 		if (state->state & exclusive_bits) {
 			*failed_start = state->start;
 			err = -EEXIST;
@@ -788,20 +785,15 @@ __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 		}
 
 		set_state_bits(tree, state, &bits);
-
 		cache_state(state, cached_state);
 		merge_state(tree, state);
 		if (last_end == (u64)-1)
 			goto out;
-
 		start = last_end + 1;
-		next_node = rb_next(&state->rb_node);
-		if (next_node && start < end && prealloc && !need_resched()) {
-			state = rb_entry(next_node, struct extent_state,
-					 rb_node);
-			if (state->start == start)
-				goto hit_next;
-		}
+		state = next_state(state);
+		if (start < end && state && state->start == start &&
+		    !need_resched())
+			goto hit_next;
 		goto search_again;
 	}
 
@@ -844,6 +836,10 @@ __set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 			if (last_end == (u64)-1)
 				goto out;
 			start = last_end + 1;
+			state = next_state(state);
+			if (start < end && state && state->start == start &&
+			    !need_resched())
+				goto hit_next;
 		}
 		goto search_again;
 	}
@@ -993,21 +989,14 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 	 * Just lock what we found and keep going
 	 */
 	if (state->start == start && state->end <= end) {
-		struct rb_node *next_node;
-
 		set_state_bits(tree, state, &bits);
-		clear_state_bit(tree, state, &clear_bits, 0);
+		state = clear_state_bit(tree, state, &clear_bits, 0);
 		if (last_end == (u64)-1)
 			goto out;
-
 		start = last_end + 1;
-		next_node = rb_next(&state->rb_node);
-		if (next_node && start < end && prealloc && !need_resched()) {
-			state = rb_entry(next_node, struct extent_state,
-					 rb_node);
-			if (state->start == start)
-				goto hit_next;
-		}
+		if (start < end && state && state->start == start &&
+		    !need_resched())
+			goto hit_next;
 		goto search_again;
 	}
 
@@ -1041,10 +1030,13 @@ int convert_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
 			goto out;
 		if (state->end <= end) {
 			set_state_bits(tree, state, &bits);
-			clear_state_bit(tree, state, &clear_bits, 0);
+			state = clear_state_bit(tree, state, &clear_bits, 0);
 			if (last_end == (u64)-1)
 				goto out;
 			start = last_end + 1;
+			if (start < end && state && state->start == start &&
+			    !need_resched())
+				goto hit_next;
 		}
 		goto search_again;
 	}