Btrfs: Implement generation numbers in block pointers

Signed-off-by: Chris Mason <chris.mason@oracle.com>

fs/btrfs/ctree.c

@@ -114,6 +114,9 @@ static int __btrfs_cow_block(struct btrfs_trans_handle *trans,
 	} else {
 		btrfs_set_node_blockptr(parent, parent_slot,
 					cow->start);
+		WARN_ON(trans->transid == 0);
+		btrfs_set_node_ptr_generation(parent, parent_slot,
+					      trans->transid);
 		btrfs_mark_buffer_dirty(parent);
 		WARN_ON(btrfs_header_generation(parent) != trans->transid);
 		btrfs_free_extent(trans, root, buf->start, buf->len, 1);
@@ -967,6 +970,7 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
 {
 	struct extent_buffer *b;
 	u64 bytenr;
+	u64 ptr_gen;
 	int slot;
 	int ret;
 	int level;
@@ -1031,10 +1035,18 @@ again:
 			if (level == lowest_level)
 				break;
 			bytenr = btrfs_node_blockptr(b, slot);
+			ptr_gen = btrfs_node_ptr_generation(b, slot);
 			if (should_reada)
 				reada_for_search(root, p, level, slot);
 			b = read_tree_block(root, bytenr,
 					    btrfs_level_size(root, level - 1));
+			if (ptr_gen != btrfs_header_generation(b)) {
+				printk("block %llu bad gen wanted %llu "
+				       "found %llu\n",
+			        (unsigned long long)b->start,
+				(unsigned long long)ptr_gen,
+			        (unsigned long long)btrfs_header_generation(b));
+			}
 		} else {
 			p->slots[level] = slot;
 			if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
@@ -1218,6 +1230,8 @@ static int insert_new_root(struct btrfs_trans_handle *trans,
 		btrfs_node_key(lower, &lower_key, 0);
 	btrfs_set_node_key(c, &lower_key, 0);
 	btrfs_set_node_blockptr(c, 0, lower->start);
+	WARN_ON(btrfs_header_generation(lower) == 0);
+	btrfs_set_node_ptr_generation(c, 0, btrfs_header_generation(lower));
 
 	btrfs_mark_buffer_dirty(c);
 
@@ -1261,6 +1275,8 @@ static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
 	}
 	btrfs_set_node_key(lower, key, slot);
 	btrfs_set_node_blockptr(lower, slot, bytenr);
+	WARN_ON(trans->transid == 0);
+	btrfs_set_node_ptr_generation(lower, slot, trans->transid);
 	btrfs_set_header_nritems(lower, nritems + 1);
 	btrfs_mark_buffer_dirty(lower);
 	return 0;

fs/btrfs/ctree.h

@@ -110,7 +110,7 @@ struct btrfs_header {
 #define BTRFS_MAX_LEVEL 8
 #define BTRFS_NODEPTRS_PER_BLOCK(r) (((r)->nodesize - \
 			        sizeof(struct btrfs_header)) / \
-			       (sizeof(struct btrfs_disk_key) + sizeof(u64)))
+			        sizeof(struct btrfs_key_ptr))
 #define __BTRFS_LEAF_DATA_SIZE(bs) ((bs) - sizeof(struct btrfs_header))
 #define BTRFS_LEAF_DATA_SIZE(r) (__BTRFS_LEAF_DATA_SIZE(r->leafsize))
 #define BTRFS_MAX_INLINE_DATA_SIZE(r) (BTRFS_LEAF_DATA_SIZE(r) - \
@@ -168,6 +168,7 @@ struct btrfs_leaf {
 struct btrfs_key_ptr {
 	struct btrfs_disk_key key;
 	__le64 blockptr;
+	__le64 generation;
 } __attribute__ ((__packed__));
 
 struct btrfs_node {
@@ -196,7 +197,13 @@ struct btrfs_path {
  */
 struct btrfs_extent_item {
 	__le32 refs;
-	__le64 owner;
+} __attribute__ ((__packed__));
+
+struct btrfs_extent_ref {
+	__le64 root;
+	__le64 generation;
+	__le64 objectid;
+	__le64 offset;
 } __attribute__ ((__packed__));
 
 struct btrfs_inode_timespec {
@@ -402,12 +409,13 @@ struct btrfs_root {
  * are used, and how many references there are to each block
  */
 #define BTRFS_EXTENT_ITEM_KEY	33
+#define BTRFS_EXTENT_REF_KEY	34
 
 /*
  * block groups give us hints into the extent allocation trees.  Which
  * blocks are free etc etc
  */
-#define BTRFS_BLOCK_GROUP_ITEM_KEY 34
+#define BTRFS_BLOCK_GROUP_ITEM_KEY 50
 
 /*
  * string items are for debugging.  They just store a short string of
@@ -529,15 +537,25 @@ BTRFS_SETGET_FUNCS(timespec_nsec, struct btrfs_inode_timespec, nsec, 32);
 
 /* struct btrfs_extent_item */
 BTRFS_SETGET_FUNCS(extent_refs, struct btrfs_extent_item, refs, 32);
-BTRFS_SETGET_FUNCS(extent_owner, struct btrfs_extent_item, owner, 64);
+
+/* struct btrfs_extent_ref */
+BTRFS_SETGET_FUNCS(ref_root, struct btrfs_extent_ref, root, 64);
+BTRFS_SETGET_FUNCS(ref_generation, struct btrfs_extent_ref, generation, 64);
+BTRFS_SETGET_FUNCS(ref_objectid, struct btrfs_extent_ref, objectid, 64);
+BTRFS_SETGET_FUNCS(ref_offset, struct btrfs_extent_ref, offset, 64);
+
+BTRFS_SETGET_STACK_FUNCS(ref_root, struct btrfs_extent_ref, root, 64);
+BTRFS_SETGET_STACK_FUNCS(ref_generation, struct btrfs_extent_ref,
+			 generation, 64);
+BTRFS_SETGET_STACK_FUNCS(ref_objectid, struct btrfs_extent_ref, objectid, 64);
+BTRFS_SETGET_STACK_FUNCS(ref_offset, struct btrfs_extent_ref, offset, 64);
 
 BTRFS_SETGET_STACK_FUNCS(stack_extent_refs, struct btrfs_extent_item,
 			 refs, 32);
-BTRFS_SETGET_STACK_FUNCS(stack_extent_owner, struct btrfs_extent_item,
-			 owner, 64);
 
 /* struct btrfs_node */
 BTRFS_SETGET_FUNCS(key_blockptr, struct btrfs_key_ptr, blockptr, 64);
+BTRFS_SETGET_FUNCS(key_generation, struct btrfs_key_ptr, generation, 64);
 
 static inline u64 btrfs_node_blockptr(struct extent_buffer *eb, int nr)
 {
@@ -556,6 +574,23 @@ static inline void btrfs_set_node_blockptr(struct extent_buffer *eb,
 	btrfs_set_key_blockptr(eb, (struct btrfs_key_ptr *)ptr, val);
 }
 
+static inline u64 btrfs_node_ptr_generation(struct extent_buffer *eb, int nr)
+{
+	unsigned long ptr;
+	ptr = offsetof(struct btrfs_node, ptrs) +
+		sizeof(struct btrfs_key_ptr) * nr;
+	return btrfs_key_generation(eb, (struct btrfs_key_ptr *)ptr);
+}
+
+static inline void btrfs_set_node_ptr_generation(struct extent_buffer *eb,
+						 int nr, u64 val)
+{
+	unsigned long ptr;
+	ptr = offsetof(struct btrfs_node, ptrs) +
+		sizeof(struct btrfs_key_ptr) * nr;
+	btrfs_set_key_generation(eb, (struct btrfs_key_ptr *)ptr, val);
+}
+
 static inline unsigned long btrfs_node_key_ptr_offset(int nr)
 {
 	return offsetof(struct btrfs_node, ptrs) +

fs/btrfs/extent-tree.c

@@ -17,6 +17,7 @@
  */
 
 #include <linux/sched.h>
+#include "hash.h"
 #include "ctree.h"
 #include "disk-io.h"
 #include "print-tree.h"
@@ -352,9 +353,63 @@ found:
 	return found_group;
 }
 
+static u64 hash_extent_ref(u64 root_objectid, u64 root_generation,
+			   u64 owner, u64 owner_offset)
+{
+	u32 high_crc = ~(u32)0;
+	u32 low_crc = ~(u32)0;
+	__le64 lenum;
+
+	lenum = cpu_to_le64(root_objectid);
+	high_crc = crc32c(high_crc, &lenum, sizeof(lenum));
+	lenum = cpu_to_le64(root_generation);
+	high_crc = crc32c(high_crc, &lenum, sizeof(lenum));
+
+	lenum = cpu_to_le64(owner);
+	low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
+
+	lenum = cpu_to_le64(owner_offset);
+	low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
+
+	return ((u64)high_crc << 32) | (u64)low_crc;
+}
+
+int insert_extent_ref(struct btrfs_trans_handle *trans,
+				struct btrfs_root *root,
+				struct btrfs_path *path,
+				u64 bytenr,
+				u64 root_objectid, u64 root_generation,
+				u64 owner, u64 owner_offset)
+{
+	u64 hash;
+	struct btrfs_key key;
+	struct btrfs_extent_ref ref;
+	struct extent_buffer *l;
+	struct btrfs_extent_item *item;
+	int ret;
+
+	btrfs_set_stack_ref_root(&ref, root_objectid);
+	btrfs_set_stack_ref_generation(&ref, root_generation);
+	btrfs_set_stack_ref_objectid(&ref, owner);
+	btrfs_set_stack_ref_offset(&ref, owner_offset);
+
+	ret = btrfs_name_hash(&ref, sizeof(ref), &hash);
+	key.offset = hash;
+	key.objectid = bytenr;
+	key.type = BTRFS_EXTENT_REF_KEY;
+
+	ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(ref));
+	while (ret == -EEXIST) {
+
+	}
+
+}
+
 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 				struct btrfs_root *root,
-				u64 bytenr, u64 num_bytes)
+				u64 bytenr, u64 num_bytes,
+				u64 root_objectid, u64 root_generation,
+				u64 owner, u64 owner_offset)
 {
 	struct btrfs_path *path;
 	int ret;
@@ -386,9 +441,10 @@ int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 	btrfs_mark_buffer_dirty(path->nodes[0]);
 
 	btrfs_release_path(root->fs_info->extent_root, path);
-	btrfs_free_path(path);
 	finish_current_insert(trans, root->fs_info->extent_root);
 	del_pending_extents(trans, root->fs_info->extent_root);
+
+	btrfs_free_path(path);
 	return 0;
 }