[PATCH 5/7] btrfs: defrag: introduce a new helper to defrag one cluster

[Qu Wenruo <wqu@suse.com>]

This new helper, defrag_one_cluster(), will defrag one cluster (at most
256K) by:

- Collect all targets
- Call defrag_one_target() on each target
  With some extra range clamping.
- Update @sectors_defraged parameter

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/ioctl.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index cd7650bcc70c..911db470aad6 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1562,6 +1562,48 @@ static int defrag_one_target(struct btrfs_inode *inode,
 	return ret;
 }
 
+static int defrag_one_cluster(struct btrfs_inode *inode,
+			      struct file_ra_state *ra,
+			      u64 start, u32 len, u32 extent_thresh,
+			      u64 newer_than, bool do_compress,
+			      unsigned long *sectors_defraged,
+			      unsigned long max_sectors)
+{
+	const u32 sectorsize = inode->root->fs_info->sectorsize;
+	struct defrag_target_range *entry;
+	struct defrag_target_range *tmp;
+	LIST_HEAD(target_list);
+	int ret;
+
+	BUILD_BUG_ON(!IS_ALIGNED(CLUSTER_SIZE, PAGE_SIZE));
+	ret = defrag_collect_targets(inode, start, len, extent_thresh,
+				     newer_than, do_compress, &target_list);
+	if (ret < 0)
+		goto out;
+
+	list_for_each_entry(entry, &target_list, list) {
+		u32 range_len = entry->len;
+
+		/* Reached the limit */
+		if (max_sectors && max_sectors == *sectors_defraged)
+			break;
+
+		if (max_sectors)
+			range_len = min_t(u32, range_len,
+				(max_sectors - *sectors_defraged) * sectorsize);
+		ret = defrag_one_target(inode, ra, entry->start, range_len);
+		if (ret < 0)
+			break;
+		*sectors_defraged += range_len;
+	}
+out:
+	list_for_each_entry_safe(entry, tmp, &target_list, list) {
+		list_del_init(&entry->list);
+		kfree(entry);
+	}
+	return ret;
+}
+
 /*
  * Btrfs entrace for defrag.
  *
-- 
2.31.1