Remove offset field from struct btrfs_extent_ref

The offset field in struct btrfs_extent_ref records the position
inside file that file extent is referenced by. In the new back
reference system, tree leaves holding reference to file extent
are recorded explicitly. We can quickly scan these tree leaves, so the
offset field is not required.

This patch also makes the back reference system check the objectid
when extents are being deleted

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

1 files changed, 10 insertions, 19 deletions

diff --git a/btrfsck.c b/btrfsck.c
index c697aaf7..494a7a77 100644
--- a/btrfsck.c
+++ b/btrfsck.c
@@ -42,7 +42,6 @@ struct extent_backref {
 	u64 root;
 	u64 generation;
 	u64 owner;
-	u64 offset;
 	u32 num_refs;
 	u32 found_ref;
 	int found_extent_tree;
@@ -159,14 +158,13 @@ static int all_backpointers_checked(struct extent_record *rec, int print_errs)
 			if (!print_errs)
 				goto out;
 			fprintf(stderr, "Backref %llu parent %llu"
-				" [%llu %llu %llu %llu %lu]"
+				" [%llu %llu %llu %lu]"
 				" not found in extent tree\n",
 				(unsigned long long)rec->start,
 				(unsigned long long)back->parent,
 				(unsigned long long)back->root,
 				(unsigned long long)back->generation,
 				(unsigned long long)back->owner,
-				(unsigned long long)back->offset,
 				(unsigned long)back->num_refs);
 		}
 		if (!back->found_ref) {
@@ -174,14 +172,13 @@ static int all_backpointers_checked(struct extent_record *rec, int print_errs)
 			if (!print_errs)
 				goto out;
 			fprintf(stderr, "Backref %llu parent %llu"
-				" [%llu %llu %llu %llu %lu]"
+				" [%llu %llu %llu %lu]"
 				" not referenced\n",
 				(unsigned long long)rec->start,
 				(unsigned long long)back->parent,
 				(unsigned long long)back->root,
 				(unsigned long long)back->generation,
 				(unsigned long long)back->owner,
-				(unsigned long long)back->offset,
 				(unsigned long)back->num_refs);
 		}
 		if (back->found_ref != back->num_refs) {
@@ -277,14 +274,13 @@ static struct extent_backref *find_backref(struct extent_record *rec,
 
 static struct extent_backref *alloc_backref(struct extent_record *rec,
 					    u64 parent, u64 root, u64 gen,
-					    u64 owner, u64 owner_offset)
+					    u64 owner)
 {
 	struct extent_backref *ref = malloc(sizeof(*ref));
 	ref->parent = parent;
 	ref->root = root;
 	ref->generation = gen;
 	ref->owner = owner;
-	ref->offset = owner_offset;
 	ref->num_refs = 0;
 	ref->found_extent_tree = 0;
 	ref->found_ref = 0;
@@ -370,7 +366,7 @@ static int add_extent_rec(struct cache_tree *extent_cache,
 
 static int add_backref(struct cache_tree *extent_cache, u64 bytenr,
 		       u64 parent, u64 root, u64 gen, u64 owner,
-		       u64 owner_offset, u32 num_refs, int found_ref)
+		       u32 num_refs, int found_ref)
 {
 	struct extent_record *rec;
 	struct extent_backref *back;
@@ -390,21 +386,19 @@ static int add_backref(struct cache_tree *extent_cache, u64 bytenr,
 	}
 	back = find_backref(rec, parent, root, gen);
 	if (!back)
-		back = alloc_backref(rec, parent, root, gen, owner,
-				     owner_offset);
+		back = alloc_backref(rec, parent, root, gen, owner);
 
 	if (found_ref) {
 		if (back->found_ref > 0 &&
 		    back->owner < BTRFS_FIRST_FREE_OBJECTID) {
 			fprintf(stderr, "Extent back ref already exists "
 				"for %llu parent %llu root %llu gen %llu "
-				"owner %llu offset %llu num_refs %lu\n",
+				"owner %llu num_refs %lu\n",
 				(unsigned long long)parent,
 				(unsigned long long)bytenr,
 				(unsigned long long)root,
 				(unsigned long long)gen,
 				(unsigned long long)owner,
-				(unsigned long long)owner_offset,
 				(unsigned long)num_refs);
 		}
 		BUG_ON(num_refs != 1);
@@ -413,13 +407,12 @@ static int add_backref(struct cache_tree *extent_cache, u64 bytenr,
 		if (back->found_extent_tree) {
 			fprintf(stderr, "Extent back ref already exists "
 				"for %llu parent %llu root %llu gen %llu "
-				"owner %llu offset %llu num_refs %lu\n",
+				"owner %llu num_refs %lu\n",
 				(unsigned long long)parent,
 				(unsigned long long)bytenr,
 				(unsigned long long)root,
 				(unsigned long long)gen,
 				(unsigned long long)owner,
-				(unsigned long long)owner_offset,
 				(unsigned long)num_refs);
 		}
 		back->num_refs = num_refs;
@@ -620,7 +613,6 @@ static int run_next_block(struct btrfs_root *root,
 					btrfs_ref_root(buf, ref),
 					btrfs_ref_generation(buf, ref),
 					btrfs_ref_objectid(buf, ref),
-					btrfs_ref_offset(buf, ref),
 					btrfs_ref_num_refs(buf, ref), 0);
 				continue;
 			}
@@ -651,8 +643,7 @@ static int run_next_block(struct btrfs_root *root,
 				    buf->start,
 				    btrfs_header_owner(buf),
 				    btrfs_header_generation(buf),
-				    btrfs_disk_key_objectid(&disk_key),
-				    btrfs_disk_key_offset(&disk_key), 1, 1);
+				    btrfs_disk_key_objectid(&disk_key), 1, 1);
 			BUG_ON(ret);
 		}
 	} else {
@@ -671,7 +662,7 @@ static int run_next_block(struct btrfs_root *root,
 			add_backref(extent_cache, ptr, buf->start,
 				btrfs_header_owner(buf),
 				btrfs_header_generation(buf),
-				level - 1, 0, 1, 1);
+				level - 1, 1, 1);
 
 			if (level > 1) {
 				add_pending(nodes, seen, ptr, size);
@@ -705,7 +696,7 @@ static int add_root_to_pending(struct extent_buffer *buf,
 
 	add_backref(extent_cache, buf->start, buf->start, root_objectid,
 		    btrfs_header_generation(buf),
-		    btrfs_header_level(buf), 0, 1, 1);
+		    btrfs_header_level(buf), 1, 1);
 	return 0;
 }