btrfs-progs: print-tree: enhance btrfs_print_leaf() to handle NULL fs_info

For mkfs and convert, we need to create a temporary fs without an
fs_info.

This makes debugging much harder that we cannot use btrfs_print_leaf()
to print the temporary tree blocks.

There are only two things causing problems for btrfs_print_leaf() if
eb->fs_info is NULL:

- print_header_info()
  Which needs to grab the checksum type from eb->fs_info.

  This can be avoided by completely skipping checksum output if
  eb->fs_info is NULL.

- btrfs_leaf_free_space()
  Which have two BUG_ON()s checking eb->fs_info, and finally calling
  BTRFS_LEAF_DATA_SIZE().

  Which can be avoided by removing the two BUG_ON()s, and use
  __BTRFS_LEAF_DATA_SIZE(eb->len) to grab the same leaf data size.

  Thankfully all call sites inside mkfs and convert are setting eb->len
  to nodesize correctly.

- __btrfs_print_leaf()
  Which calls BTRFS_LEAF_DATA_SIZE(eb->fs_info).

  Can be avoided by the same method above.

With those changes, we can call btrfs_print_leaf() inside a debugger
for temporary fses created by mkfs and convert.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: adam900710

kernel-shared/ctree.c

@@ -1887,9 +1887,7 @@ int btrfs_leaf_free_space(const struct extent_buffer *leaf)
 	u32 leaf_data_size;
 	int ret;
 
-	BUG_ON(!leaf->fs_info);
-	BUG_ON(leaf->fs_info->nodesize != leaf->len);
-	leaf_data_size = BTRFS_LEAF_DATA_SIZE(leaf->fs_info);
+	leaf_data_size = __BTRFS_LEAF_DATA_SIZE(leaf->len);
 	ret = leaf_data_size - leaf_space_used(leaf, 0 ,nritems);
 	if (ret < 0) {
 		printk("leaf free space ret %d, leaf data size %u, used %d nritems %d\n",

kernel-shared/print-tree.c

@@ -1344,8 +1344,7 @@ static void print_header_info(struct extent_buffer *eb, unsigned int mode)
 	u32 nr;
 	u8 backref_rev;
 	char csum_str[2 * BTRFS_CSUM_SIZE + 8 /* strlen(" csum 0x") */ + 1];
-	int i;
-	int csum_size = fs_info->csum_size;
+	const int csum_size = (fs_info ? fs_info->csum_size : 0);
 
 	flags = btrfs_header_flags(eb) & ~BTRFS_BACKREF_REV_MASK;
 	backref_rev = btrfs_header_flags(eb) >> BTRFS_BACKREF_REV_SHIFT;
@@ -1372,7 +1371,7 @@ static void print_header_info(struct extent_buffer *eb, unsigned int mode)
 
 		strcpy(csum_str, " csum 0x");
 		tmp = csum_str + strlen(csum_str);
-		for (i = 0; i < csum_size; i++) {
+		for (int i = 0; i < csum_size; i++) {
 			sprintf(tmp, "%02x", tree_csum[i]);
 			tmp++;
 			tmp++;
@@ -1387,18 +1386,20 @@ static void print_header_info(struct extent_buffer *eb, unsigned int mode)
 	       csum_str);
 
 #if EXPERIMENTAL
-	printf("checksum stored ");
-	for (i = 0; i < csum_size; i++)
-		printf("%02hhx", (int)(eb->data[i]));
-	printf("\n");
-	memset(csum, 0, sizeof(csum));
-	btrfs_csum_data(btrfs_super_csum_type(fs_info->super_copy),
-			(u8 *)eb->data + BTRFS_CSUM_SIZE,
-			csum, fs_info->nodesize - BTRFS_CSUM_SIZE);
-	printf("checksum calced ");
-	for (i = 0; i < csum_size; i++)
-		printf("%02hhx", (int)(csum[i]));
-	printf("\n");
+	if (fs_info) {
+		printf("checksum stored ");
+		for (int i = 0; i < csum_size; i++)
+			printf("%02hhx", (int)(eb->data[i]));
+		printf("\n");
+		memset(csum, 0, sizeof(csum));
+		btrfs_csum_data(btrfs_super_csum_type(fs_info->super_copy),
+				(u8 *)eb->data + BTRFS_CSUM_SIZE,
+				csum, fs_info->nodesize - BTRFS_CSUM_SIZE);
+		printf("checksum calced ");
+		for (int i = 0; i < csum_size; i++)
+			printf("%02hhx", (int)(csum[i]));
+		printf("\n");
+	}
 #endif
 
 	print_uuids(eb);
@@ -1478,10 +1479,10 @@ static void print_dev_replace_item(struct extent_buffer *eb, struct btrfs_dev_re
 void __btrfs_print_leaf(struct extent_buffer *eb, unsigned int mode)
 {
 	struct btrfs_disk_key disk_key;
-	u32 leaf_data_size = BTRFS_LEAF_DATA_SIZE(eb->fs_info);
+	u32 leaf_data_size = __BTRFS_LEAF_DATA_SIZE(eb->len);
 	u32 i;
 	u32 nr;
-	const bool print_csum_items = (mode & BTRFS_PRINT_TREE_CSUM_ITEMS);
+	const bool print_csum_items = (mode & BTRFS_PRINT_TREE_CSUM_ITEMS) && eb->fs_info;
 
 	print_header_info(eb, mode);
 	nr = btrfs_header_nritems(eb);