linux-ext4 - [RFC 05/13] libext2fs: blkmap64_rb: Add rbtree bmap merge logic changes

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Message-Id: <bb03a40f73af19434792a87a1ee32613d8c00c32.1656912918.git.ritesh.list@gmail.com>
Date:   Mon,  4 Jul 2022 12:36:54 +0530
From:   Ritesh Harjani <ritesh.list@...il.com>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Harshad Shirwadkar <harshadshirwadkar@...il.com>,
        Andreas Dilger <adilger@...ger.ca>,
        linux-ext4 <linux-ext4@...r.kernel.org>,
        Wang Shilong <wshilong@....com>,
        Ritesh Harjani <ritesh.list@...il.com>
Subject: [RFC 05/13] libext2fs: blkmap64_rb: Add rbtree bmap merge logic changes

From: Wang Shilong <wshilong@....com>

Add rbtree bmap merge logic changes.

Signed-off-by: Ritesh Harjani <ritesh.list@...il.com>
Signed-off-by: Wang Shilong <wshilong@....com>
---
 lib/ext2fs/blkmap64_rb.c | 65 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/lib/ext2fs/blkmap64_rb.c b/lib/ext2fs/blkmap64_rb.c
index 0df58dc7..d7c88aef 100644
--- a/lib/ext2fs/blkmap64_rb.c
+++ b/lib/ext2fs/blkmap64_rb.c
@@ -977,11 +977,76 @@ static void rb_print_stats(ext2fs_generic_bitmap_64 bitmap EXT2FS_ATTR((unused))
 }
 #endif
 
+static errcode_t rb_merge_bmap(ext2fs_generic_bitmap_64 src,
+			       ext2fs_generic_bitmap_64 dest,
+			       ext2fs_generic_bitmap_64 dup,
+			       ext2fs_generic_bitmap_64 dup_allowed)
+{
+	struct ext2fs_rb_private *src_bp, *dest_bp, *dup_bp = NULL;
+	struct bmap_rb_extent *src_ext;
+	struct rb_node *src_node;
+	errcode_t retval = 0;
+	int dup_found = 0;
+	__u64 i;
+
+	src_bp = (struct ext2fs_rb_private *) src->private;
+	dest_bp = (struct ext2fs_rb_private *) dest->private;
+	if (dup)
+		dup_bp = (struct ext2fs_rb_private *)dup->private;
+	src_bp->rcursor = NULL;
+	dest_bp->rcursor = NULL;
+
+	src_node = ext2fs_rb_first(&src_bp->root);
+	while (src_node) {
+		src_ext = node_to_extent(src_node);
+		retval = rb_test_clear_bmap_extent(dest,
+					src_ext->start + src->start,
+					src_ext->count);
+		if (retval) {
+			rb_insert_extent(src_ext->start, src_ext->count,
+					 dest_bp);
+			goto next;
+		}
+
+		/* unlikely case, do it one by one block */
+		for (i = src_ext->start;
+		     i < src_ext->start + src_ext->count; i++) {
+			retval = rb_test_clear_bmap_extent(dest, i + src->start, 1);
+			if (retval) {
+				rb_insert_extent(i, 1, dest_bp);
+				continue;
+			}
+			if (dup_allowed) {
+				retval = rb_test_clear_bmap_extent(dup_allowed,
+							i + src->start, 1);
+				/* not existed in dup_allowed */
+				if (retval) {
+					dup_found = 1;
+					if (dup_bp)
+						rb_insert_extent(i, 1, dup_bp);
+				} /* else we conside it not duplicated */
+			} else {
+				if (dup_bp)
+					rb_insert_extent(i, 1, dup_bp);
+				dup_found = 1;
+			}
+		}
+next:
+		src_node = ext2fs_rb_next(src_node);
+	}
+
+	if (dup_found && dup)
+		return EEXIST;
+
+	return 0;
+}
+
 struct ext2_bitmap_ops ext2fs_blkmap64_rbtree = {
 	.type = EXT2FS_BMAP64_RBTREE,
 	.new_bmap = rb_new_bmap,
 	.free_bmap = rb_free_bmap,
 	.copy_bmap = rb_copy_bmap,
+	.merge_bmap = rb_merge_bmap,
 	.resize_bmap = rb_resize_bmap,
 	.mark_bmap = rb_mark_bmap,
 	.unmark_bmap = rb_unmark_bmap,
-- 
2.35.3