btrfs: return bool from lock_extent_buffer_for_io

lock_extent_buffer_for_io never returns a negative error value, so switch
the return value to a simple bool.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
[ keep noinline_for_stack ]
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -1629,18 +1629,17 @@ static void end_extent_buffer_writeback(struct extent_buffer *eb)
  *
  * May try to flush write bio if we can't get the lock.
  *
- * Return  0 if the extent buffer doesn't need to be submitted.
- *           (E.g. the extent buffer is not dirty)
- * Return >0 is the extent buffer is submitted to bio.
- * Return <0 if something went wrong, no page is locked.
+ * Return %false if the extent buffer doesn't need to be submitted (e.g. the
+ * extent buffer is not dirty)
+ * Return %true is the extent buffer is submitted to bio.
  */
-static noinline_for_stack int lock_extent_buffer_for_io(struct extent_buffer *eb,
+static noinline_for_stack bool lock_extent_buffer_for_io(struct extent_buffer *eb,
 			  struct btrfs_bio_ctrl *bio_ctrl)
 {
 	struct btrfs_fs_info *fs_info = eb->fs_info;
 	int i, num_pages;
 	int flush = 0;
-	int ret = 0;
+	bool ret = false;
 
 	if (!btrfs_try_tree_write_lock(eb)) {
 		submit_write_bio(bio_ctrl, 0);
@@ -1651,7 +1650,7 @@ static noinline_for_stack int lock_extent_buffer_for_io(struct extent_buffer *eb
 	if (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
 		btrfs_tree_unlock(eb);
 		if (bio_ctrl->wbc->sync_mode != WB_SYNC_ALL)
-			return 0;
+			return false;
 		if (!flush) {
 			submit_write_bio(bio_ctrl, 0);
 			flush = 1;
@@ -1678,7 +1677,7 @@ static noinline_for_stack int lock_extent_buffer_for_io(struct extent_buffer *eb
 		percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
 					 -eb->len,
 					 fs_info->dirty_metadata_batch);
-		ret = 1;
+		ret = true;
 	} else {
 		spin_unlock(&eb->refs_lock);
 	}
@@ -2012,7 +2011,6 @@ static int submit_eb_subpage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl)
 	u64 page_start = page_offset(page);
 	int bit_start = 0;
 	int sectors_per_node = fs_info->nodesize >> fs_info->sectorsize_bits;
-	int ret;
 
 	/* Lock and write each dirty extent buffers in the range */
 	while (bit_start < fs_info->subpage_info->bitmap_nr_bits) {
@@ -2058,25 +2056,13 @@ static int submit_eb_subpage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl)
 		if (!eb)
 			continue;
 
-		ret = lock_extent_buffer_for_io(eb, bio_ctrl);
-		if (ret == 0) {
-			free_extent_buffer(eb);
-			continue;
-		}
-		if (ret < 0) {
-			free_extent_buffer(eb);
-			goto cleanup;
-		}
+		if (lock_extent_buffer_for_io(eb, bio_ctrl)) {
 			write_one_subpage_eb(eb, bio_ctrl);
-		free_extent_buffer(eb);
 			submitted++;
 		}
+		free_extent_buffer(eb);
+	}
 	return submitted;
-
-cleanup:
-	/* We hit error, end bio for the submitted extent buffers */
-	submit_write_bio(bio_ctrl, ret);
-	return ret;
 }
 
 /*
@@ -2155,8 +2141,7 @@ static int submit_eb_page(struct page *page, struct btrfs_bio_ctrl *bio_ctrl,
 
 	*eb_context = eb;
 
-	ret = lock_extent_buffer_for_io(eb, bio_ctrl);
-	if (ret <= 0) {
+	if (!lock_extent_buffer_for_io(eb, bio_ctrl)) {
 		btrfs_revert_meta_write_pointer(cache, eb);
 		if (cache)
 			btrfs_put_block_group(cache);