Btrfs: verify csums on read

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

1 files changed, 26 insertions, 11 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index f2c1dd40c08..f5db2b93650 100644
--- 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;
 }