btrfs: use next_state instead of rb_next where we can

We can simplify a lot of these functions where we have to cycle through
extent_state's by simply using next_state() instead of rb_next().  In
many spots this allows us to do things like

while (state) {
	/* whatever */
	state = next_state(state);
}

instead of

while (1) {
	state = rb_entry(n, struct extent_state, rb_node);
	n = rb_next(n);
	if (!n)
		break;
}

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent-io-tree.c b/fs/btrfs/extent-io-tree.c
index 6b23d4d091c54f8a1ace9079244133b202c640e3..0d283a5ac9f7bad49991199b2b8a64cf658df997 100644 (file)
--- a/fs/btrfs/extent-io-tree.c
+++ b/fs/btrfs/extent-io-tree.c
@@ -748,12 +748,10 @@ again:
                 * range starts.
                 */
                node = tree_search(tree, start);
-process_node:
                if (!node)
                        break;
-
                state = rb_entry(node, struct extent_state, rb_node);
-
+process_node:
                if (state->start > end)
                        goto out;
 
@@ -770,7 +768,7 @@ process_node:
                        break;
 
                if (!cond_resched_lock(&tree->lock)) {
-                       node = rb_next(node);
+                       state = next_state(state);
                        goto process_node;
                }
        }
@@ -815,15 +813,13 @@ static struct extent_state *find_first_extent_bit_state(struct extent_io_tree *t
        node = tree_search(tree, start);
        if (!node)
                goto out;
+       state = rb_entry(node, struct extent_state, rb_node);
 
-       while (1) {
-               state = rb_entry(node, struct extent_state, rb_node);
+       while (state) {
                if (state->end >= start && (state->state & bits))
                        return state;
 
-               node = rb_next(node);
-               if (!node)
-                       break;
+               state = next_state(state);
        }
 out:
        return NULL;
@@ -939,8 +935,8 @@ bool btrfs_find_delalloc_range(struct extent_io_tree *tree, u64 *start,
                goto out;
        }
 
-       while (1) {
-               state = rb_entry(node, struct extent_state, rb_node);
+       state = rb_entry(node, struct extent_state, rb_node);
+       while (state) {
                if (found && (state->start != cur_start ||
                              (state->state & EXTENT_BOUNDARY))) {
                        goto out;
@@ -958,12 +954,10 @@ bool btrfs_find_delalloc_range(struct extent_io_tree *tree, u64 *start,
                found = true;
                *end = state->end;
                cur_start = state->end + 1;
-               node = rb_next(node);
                total_bytes += state->end - state->start + 1;
                if (total_bytes >= max_bytes)
                        break;
-               if (!node)
-                       break;
+               state = next_state(state);
        }
 out:
        spin_unlock(&tree->lock);
@@ -1514,18 +1508,15 @@ void find_first_clear_extent_bit(struct extent_io_tree *tree, u64 start,
         * Find the longest stretch from start until an entry which has the
         * bits set
         */
-       while (1) {
-               state = rb_entry(node, struct extent_state, rb_node);
+       state = rb_entry(node, struct extent_state, rb_node);
+       while (state) {
                if (state->end >= start && !(state->state & bits)) {
                        *end_ret = state->end;
                } else {
                        *end_ret = state->start - 1;
                        break;
                }
-
-               node = rb_next(node);
-               if (!node)
-                       break;
+               state = next_state(state);
        }
 out:
        spin_unlock(&tree->lock);
@@ -1563,8 +1554,8 @@ u64 count_range_bits(struct extent_io_tree *tree,
        if (!node)
                goto out;
 
-       while (1) {
-               state = rb_entry(node, struct extent_state, rb_node);
+       state = rb_entry(node, struct extent_state, rb_node);
+       while (state) {
                if (state->start > search_end)
                        break;
                if (contig && found && state->start > last + 1)
@@ -1582,9 +1573,7 @@ u64 count_range_bits(struct extent_io_tree *tree,
                } else if (contig && found) {
                        break;
                }
-               node = rb_next(node);
-               if (!node)
-                       break;
+               state = next_state(state);
        }
 out:
        spin_unlock(&tree->lock);
@@ -1609,9 +1598,11 @@ int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
                node = &cached->rb_node;
        else
                node = tree_search(tree, start);
-       while (node && start <= end) {
-               state = rb_entry(node, struct extent_state, rb_node);
+       if (!node)
+               goto out;
 
+       state = rb_entry(node, struct extent_state, rb_node);
+       while (state && start <= end) {
                if (filled && state->start > start) {
                        bitset = 0;
                        break;
@@ -1635,13 +1626,13 @@ int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
                start = state->end + 1;
                if (start > end)
                        break;
-               node = rb_next(node);
-               if (!node) {
-                       if (filled)
-                               bitset = 0;
-                       break;
-               }
+               state = next_state(state);
        }
+
+       /* We ran out of states and were still inside of our range. */
+       if (filled && !state)
+               bitset = 0;
+out:
        spin_unlock(&tree->lock);
        return bitset;
 }