Btrfs: verify csums on read

[deliverable/linux.git] / fs / btrfs / disk-io.c

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index f2c1dd40c087871ba435b49ff74d776edfa819b5..f5db2b93650293c191764049d4ade4cb4e8f6523 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/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;
 }