+ u64 cur;
+ int ret;
+
+ ASSERT(page_index <= last_index);
+ page = find_lock_page(inode->i_mapping, page_index);
+ if (!page) {
+ page_cache_sync_readahead(inode->i_mapping, ra, NULL,
+ page_index, last_index + 1 - page_index);
+ page = find_or_create_page(inode->i_mapping, page_index, mask);
+ if (!page)
+ return -ENOMEM;
+ }
+ ret = set_page_extent_mapped(page);
+ if (ret < 0)
+ goto release_page;
+
+ if (PageReadahead(page))
+ page_cache_async_readahead(inode->i_mapping, ra, NULL, page,
+ page_index, last_index + 1 - page_index);
+
+ if (!PageUptodate(page)) {
+ btrfs_readpage(NULL, page);
+ lock_page(page);
+ if (!PageUptodate(page)) {
+ ret = -EIO;
+ goto release_page;
+ }
+ }
+
+ page_start = page_offset(page);
+ page_end = page_start + PAGE_SIZE - 1;
+
+ /*
+ * Start from the cluster, as for subpage case, the cluster can start
+ * inside the page.
+ */
+ cur = max(page_start, cluster->boundary[*cluster_nr] - offset);
+ while (cur <= page_end) {
+ u64 extent_start = cluster->boundary[*cluster_nr] - offset;
+ u64 extent_end = get_cluster_boundary_end(cluster,
+ *cluster_nr) - offset;
+ u64 clamped_start = max(page_start, extent_start);
+ u64 clamped_end = min(page_end, extent_end);
+ u32 clamped_len = clamped_end + 1 - clamped_start;
+
+ /* Reserve metadata for this range */
+ ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
+ clamped_len);
+ if (ret)
+ goto release_page;
+
+ /* Mark the range delalloc and dirty for later writeback */
+ lock_extent(&BTRFS_I(inode)->io_tree, clamped_start, clamped_end);
+ ret = btrfs_set_extent_delalloc(BTRFS_I(inode), clamped_start,
+ clamped_end, 0, NULL);
+ if (ret) {
+ clear_extent_bits(&BTRFS_I(inode)->io_tree,
+ clamped_start, clamped_end,
+ EXTENT_LOCKED | EXTENT_BOUNDARY);
+ btrfs_delalloc_release_metadata(BTRFS_I(inode),
+ clamped_len, true);
+ btrfs_delalloc_release_extents(BTRFS_I(inode),
+ clamped_len);
+ goto release_page;
+ }
+ btrfs_page_set_dirty(fs_info, page, clamped_start, clamped_len);
+
+ /*
+ * Set the boundary if it's inside the page.
+ * Data relocation requires the destination extents to have the
+ * same size as the source.
+ * EXTENT_BOUNDARY bit prevents current extent from being merged
+ * with previous extent.
+ */
+ if (in_range(cluster->boundary[*cluster_nr] - offset,
+ page_start, PAGE_SIZE)) {
+ u64 boundary_start = cluster->boundary[*cluster_nr] -
+ offset;
+ u64 boundary_end = boundary_start +
+ fs_info->sectorsize - 1;
+
+ set_extent_bits(&BTRFS_I(inode)->io_tree,
+ boundary_start, boundary_end,
+ EXTENT_BOUNDARY);
+ }
+ unlock_extent(&BTRFS_I(inode)->io_tree, clamped_start, clamped_end);
+ btrfs_delalloc_release_extents(BTRFS_I(inode), clamped_len);
+ cur += clamped_len;
+
+ /* Crossed extent end, go to next extent */
+ if (cur >= extent_end) {
+ (*cluster_nr)++;
+ /* Just finished the last extent of the cluster, exit. */
+ if (*cluster_nr >= cluster->nr)
+ break;
+ }
+ }
+ unlock_page(page);
+ put_page(page);
+
+ balance_dirty_pages_ratelimited(inode->i_mapping);
+ btrfs_throttle(fs_info);
+ if (btrfs_should_cancel_balance(fs_info))
+ ret = -ECANCELED;
+ return ret;
+
+release_page:
+ unlock_page(page);
+ put_page(page);
+ return ret;
+}
+
+static int relocate_file_extent_cluster(struct inode *inode,
+ struct file_extent_cluster *cluster)
+{