Btrfs: verify csums on read

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

fs/btrfs/ctree.c

@@ -109,14 +109,14 @@ static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
 		return 1;
 	if (k1.objectid < k2->objectid)
 		return -1;
-	if (k1.flags > k2->flags)
-		return 1;
-	if (k1.flags < k2->flags)
-		return -1;
 	if (k1.offset > k2->offset)
 		return 1;
 	if (k1.offset < k2->offset)
 		return -1;
+	if (k1.flags > k2->flags)
+		return 1;
+	if (k1.flags < k2->flags)
+		return -1;
 	return 0;
 }
 
@@ -1165,7 +1165,6 @@ int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, struct btrfs_root
 		BUG();
 	ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
 	if (ret == 0) {
-		btrfs_release_path(root, path);
 		return -EEXIST;
 	}
 	if (ret < 0)

fs/btrfs/ctree.h

@@ -21,6 +21,9 @@ struct btrfs_transaction;
  */
 #define BTRFS_NAME_LEN 255
 
+/* 32 bytes in various csum fields */
+#define BTRFS_CSUM_SIZE 32
+
 /*
  * the key defines the order in the tree, and so it also defines (optimal)
  * block layout.  objectid corresonds to the inode number.  The flags
@@ -37,21 +40,21 @@ struct btrfs_transaction;
  */
 struct btrfs_disk_key {
 	__le64 objectid;
-	__le32 flags;
 	__le64 offset;
+	__le32 flags;
 } __attribute__ ((__packed__));
 
 struct btrfs_key {
 	u64 objectid;
-	u32 flags;
 	u64 offset;
+	u32 flags;
 } __attribute__ ((__packed__));
 
 /*
  * every tree block (leaf or node) starts with this header.
  */
 struct btrfs_header {
-	__le32 csum[8];
+	u8 csum[BTRFS_CSUM_SIZE];
 	u8 fsid[16]; /* FS specific uuid */
 	__le64 blocknr; /* which block this node is supposed to live in */
 	__le64 generation;
@@ -75,7 +78,7 @@ struct buffer_head;
  * it currently lacks any block count etc etc
  */
 struct btrfs_super_block {
-	__le32 csum[8];
+	u8 csum[BTRFS_CSUM_SIZE];
 	/* the first 3 fields must match struct btrfs_header */
 	u8 fsid[16];    /* FS specific uuid */
 	__le64 blocknr; /* this block number */
@@ -147,7 +150,7 @@ struct btrfs_extent_item {
 } __attribute__ ((__packed__));
 
 struct btrfs_inode_timespec {
-	__le32 sec;
+	__le64 sec;
 	__le32 nsec;
 } __attribute__ ((__packed__));
 
@@ -214,6 +217,10 @@ struct btrfs_file_extent_item {
 	__le64 num_blocks;
 } __attribute__ ((__packed__));
 
+struct btrfs_csum_item {
+	u8 csum[BTRFS_CSUM_SIZE];
+} __attribute__ ((__packed__));
+
 struct btrfs_inode_map_item {
 	struct btrfs_disk_key key;
 } __attribute__ ((__packed__));
@@ -283,27 +290,32 @@ struct btrfs_root {
  * a (hopefully) huge chunk of disk
  */
 #define BTRFS_EXTENT_DATA_KEY	4
+/*
+ * csum items have the checksums for data in the extents
+ */
+#define BTRFS_CSUM_ITEM_KEY	5
+
 /*
  * root items point to tree roots.  There are typically in the root
  * tree used by the super block to find all the other trees
  */
-#define BTRFS_ROOT_ITEM_KEY	5
+#define BTRFS_ROOT_ITEM_KEY	6
 /*
  * extent items are in the extent map tree.  These record which blocks
  * are used, and how many references there are to each block
  */
-#define BTRFS_EXTENT_ITEM_KEY	6
+#define BTRFS_EXTENT_ITEM_KEY	7
 
 /*
  * the inode map records which inode numbers are in use and where
  * they actually live on disk
  */
-#define BTRFS_INODE_MAP_ITEM_KEY 7
+#define BTRFS_INODE_MAP_ITEM_KEY 8
 /*
  * string items are for debugging.  They just store a short string of
  * data in the FS
  */
-#define BTRFS_STRING_ITEM_KEY	8
+#define BTRFS_STRING_ITEM_KEY	9
 
 static inline u64 btrfs_inode_generation(struct btrfs_inode_item *i)
 {
@@ -407,15 +419,15 @@ static inline void btrfs_set_inode_compat_flags(struct btrfs_inode_item *i,
 	i->compat_flags = cpu_to_le16(val);
 }
 
-static inline u32 btrfs_timespec_sec(struct btrfs_inode_timespec *ts)
+static inline u64 btrfs_timespec_sec(struct btrfs_inode_timespec *ts)
 {
-	return le32_to_cpu(ts->sec);
+	return le64_to_cpu(ts->sec);
 }
 
 static inline void btrfs_set_timespec_sec(struct btrfs_inode_timespec *ts,
-					  u32 val)
+					  u64 val)
 {
-	ts->sec = cpu_to_le32(val);
+	ts->sec = cpu_to_le64(val);
 }
 
 static inline u32 btrfs_timespec_nsec(struct btrfs_inode_timespec *ts)
@@ -429,8 +441,6 @@ static inline void btrfs_set_timespec_nsec(struct btrfs_inode_timespec *ts,
 	ts->nsec = cpu_to_le32(val);
 }
 
-
-
 static inline u64 btrfs_extent_owner(struct btrfs_extent_item *ei)
 {
 	return le64_to_cpu(ei->owner);
@@ -905,4 +915,11 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 			     struct btrfs_root *root,
 			     struct btrfs_path *path, u64 objectid,
 			     u64 blocknr, int mod);
+int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root,
+			  u64 objectid, u64 offset,
+			  char *data, size_t len);
+int btrfs_csum_verify_file_block(struct btrfs_root *root,
+				 u64 objectid, u64 offset,
+				 char *data, size_t len);
 #endif

fs/btrfs/disk-io.c

@@ -127,31 +127,46 @@ static int btree_get_block(struct inode *inode, sector_t iblock,
 	return 0;
 }
 
-static int csum_tree_block(struct btrfs_root * root, struct buffer_head *bh,
-			    int verify)
+int btrfs_csum_data(struct btrfs_root * root, char *data, size_t len,
+		    char *result)
 {
-	struct btrfs_node *node = btrfs_buffer_node(bh);
 	struct scatterlist sg;
 	struct crypto_hash *tfm = root->fs_info->hash_tfm;
 	struct hash_desc desc;
 	int ret;
-	char result[32];
 
 	desc.tfm = tfm;
 	desc.flags = 0;
-	sg_init_one(&sg, bh->b_data + 32, bh->b_size - 32);
+	sg_init_one(&sg, data, len);
 	spin_lock(&root->fs_info->hash_lock);
-	ret = crypto_hash_digest(&desc, &sg, bh->b_size - 32, result);
+	ret = crypto_hash_digest(&desc, &sg, len, result);
 	spin_unlock(&root->fs_info->hash_lock);
 	if (ret) {
 		printk("sha256 digest failed\n");
 	}
+	return ret;
+}
+static int csum_tree_block(struct btrfs_root *root, struct buffer_head *bh,
+			   int verify)
+{
+	char result[BTRFS_CSUM_SIZE];
+	int ret;
+	struct btrfs_node *node;
+
+	ret = btrfs_csum_data(root, bh->b_data + BTRFS_CSUM_SIZE,
+			      bh->b_size - BTRFS_CSUM_SIZE, result);
+	if (ret)
+		return ret;
 	if (verify) {
-		if (memcmp(node->header.csum, result, sizeof(result)))
-			printk("csum verify failed on %Lu\n", bh->b_blocknr);
-		return -EINVAL;
-	} else
-		memcpy(node->header.csum, result, sizeof(node->header.csum));
+		if (memcmp(bh->b_data, result, BTRFS_CSUM_SIZE)) {
+			printk("checksum verify failed on %lu\n",
+			       bh->b_blocknr);
+			return 1;
+		}
+	} else {
+		node = btrfs_buffer_node(bh);
+		memcpy(&node->header.csum, result, BTRFS_CSUM_SIZE);
+	}
 	return 0;
 }
 

fs/btrfs/disk-io.h

@@ -39,4 +39,6 @@ void btrfs_block_release(struct btrfs_root *root, struct buffer_head *buf);
 int write_ctree_super(struct btrfs_trans_handle *trans,
 		      struct btrfs_root *root);
 struct buffer_head *btrfs_find_tree_block(struct btrfs_root *root, u64 blocknr);
+int btrfs_csum_data(struct btrfs_root * root, char *data, size_t len,
+		    char *result);
 #endif

fs/btrfs/file-item.c

@@ -57,3 +57,63 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 	ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 	return ret;
 }
+
+int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root,
+			  u64 objectid, u64 offset,
+			  char *data, size_t len)
+{
+	int ret;
+	struct btrfs_key file_key;
+	struct btrfs_path path;
+	struct btrfs_csum_item *item;
+
+	btrfs_init_path(&path);
+	file_key.objectid = objectid;
+	file_key.offset = offset;
+	file_key.flags = 0;
+	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+	ret = btrfs_insert_empty_item(trans, root, &path, &file_key,
+				      BTRFS_CSUM_SIZE);
+	if (ret != 0 && ret != -EEXIST)
+		goto fail;
+	item = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
+			      struct btrfs_csum_item);
+	ret = 0;
+	ret = btrfs_csum_data(root, data, len, item->csum);
+	mark_buffer_dirty(path.nodes[0]);
+fail:
+	btrfs_release_path(root, &path);
+	return ret;
+}
+
+int btrfs_csum_verify_file_block(struct btrfs_root *root,
+				 u64 objectid, u64 offset,
+				 char *data, size_t len)
+{
+	int ret;
+	struct btrfs_key file_key;
+	struct btrfs_path path;
+	struct btrfs_csum_item *item;
+	char result[BTRFS_CSUM_SIZE];
+
+	btrfs_init_path(&path);
+	file_key.objectid = objectid;
+	file_key.offset = offset;
+	file_key.flags = 0;
+	btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+	ret = btrfs_search_slot(NULL, root, &file_key, &path, 0, 0);
+	if (ret)
+		goto fail;
+	item = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
+			      struct btrfs_csum_item);
+	ret = 0;
+	ret = btrfs_csum_data(root, data, len, result);
+	WARN_ON(ret);
+	if (memcmp(result, item->csum, BTRFS_CSUM_SIZE))
+		ret = 1;
+fail:
+	btrfs_release_path(root, &path);
+	return ret;
+}
+