[PATCH] btrfs-progs: Fix checksum output for "checksum verify failed"

["Dāvis Mosāns" <davispuh@gmail.com>]

Currently only single checksum byte is outputted.
This fixes it so that full checksum is outputted.

Signed-off-by: Dāvis Mosāns <davispuh@gmail.com>
---
 kernel-shared/disk-io.c | 47 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 42 insertions(+), 5 deletions(-)

diff --git a/kernel-shared/disk-io.c b/kernel-shared/disk-io.c
index 6f584986..8773eed7 100644
--- a/kernel-shared/disk-io.c
+++ b/kernel-shared/disk-io.c
@@ -160,10 +160,45 @@ int btrfs_csum_data(u16 csum_type, const u8 *data, u8 *out, size_t len)
 	return -1;
 }
 
+int btrfs_format_csum(u16 csum_type, const char *data, char *output)
+{
+	int i;
+	int csum_len = 0;
+	int position = 0;
+	int direction = 1;
+	switch (csum_type) {
+		case BTRFS_CSUM_TYPE_CRC32:
+			csum_len = 4;
+			position = csum_len - 1;
+			direction = -1;
+			break;
+		case BTRFS_CSUM_TYPE_XXHASH:
+			csum_len = 8;
+			position = csum_len - 1;
+			direction = -1;
+			break;
+		case BTRFS_CSUM_TYPE_SHA256:
+		case BTRFS_CSUM_TYPE_BLAKE2:
+			csum_len = 32;
+			break;
+		default:
+			fprintf(stderr, "ERROR: unknown csum type: %d\n", csum_type);
+			ASSERT(0);
+	}
+
+	for (i = 0; i < csum_len; i++) {
+		sprintf(output + i*2, "%02X", data[position + i*direction] & 0xFF);
+	}
+
+	return csum_len;
+}
+
 static int __csum_tree_block_size(struct extent_buffer *buf, u16 csum_size,
 				  int verify, int silent, u16 csum_type)
 {
 	u8 result[BTRFS_CSUM_SIZE];
+	char found[BTRFS_CSUM_SIZE * 2 + 1]; // 2 hex chars for each byte + null
+	char expected[BTRFS_CSUM_SIZE * 2 + 1];
 	u32 len;
 
 	len = buf->len - BTRFS_CSUM_SIZE;
@@ -172,12 +207,14 @@ static int __csum_tree_block_size(struct extent_buffer *buf, u16 csum_size,
 
 	if (verify) {
 		if (memcmp_extent_buffer(buf, result, 0, csum_size)) {
-			/* FIXME: format */
-			if (!silent)
-				printk("checksum verify failed on %llu found %08X wanted %08X\n",
+			if (!silent) {
+				btrfs_format_csum(csum_type, (char *)result, found);
+				btrfs_format_csum(csum_type, buf->data, expected);
+				printk("checksum verify failed on %llu found %s wanted %s\n",
 				       (unsigned long long)buf->start,
-				       result[0],
-				       buf->data[0]);
+				       found,
+				       expected);
+			}
 			return 1;
 		}
 	} else {
-- 
2.30.1