Commit c3267bba authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: Refactor check_leaf function for later expansion 



Current check_leaf() function does a good job checking key order and
item offset/size.

However it only checks from slot 0 to the last but one slot, this is
good but makes later expansion hard.

So this refactoring iterates from slot 0 to the last slot.
For key comparison, it uses a key with all 0 as initial key, so all
valid keys should be larger than that.

And for item size/offset checks, it compares current item end with
previous item offset.
For slot 0, use leaf end as a special case.

This makes later item/key offset checks and item size checks easier to
be implemented.

Also, makes check_leaf() to return -EUCLEAN other than -EIO to indicate
error.

Signed-off-by: default avatarQu Wenruo <quwenruo.btrfs@gmx.com>
Reviewed-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 6018ba0a

fs/btrfs/disk-io.c

+27 −23
Original line number Diff line number Diff line
@@ -553,8 +553,9 @@ static noinline int check_leaf(struct btrfs_root *root, 
			       struct extent_buffer *leaf)

{

	struct btrfs_fs_info *fs_info = root->fs_info;

	/* No valid key type is 0, so all key should be larger than this key */

	struct btrfs_key prev_key = {0, 0, 0};

	struct btrfs_key key;

	struct btrfs_key leaf_key;

	u32 nritems = btrfs_header_nritems(leaf);

	int slot;
@@ -587,7 +588,7 @@ static noinline int check_leaf(struct btrfs_root *root, 
				CORRUPT("non-root leaf's nritems is 0",

					leaf, check_root, 0);

				free_extent_buffer(eb);

				return -EIO;

				return -EUCLEAN;

			}

			free_extent_buffer(eb);

		}
@@ -597,28 +598,23 @@ static noinline int check_leaf(struct btrfs_root *root, 
	if (nritems == 0)

		return 0;



	/* Check the 0 item */

	if (btrfs_item_offset_nr(leaf, 0) + btrfs_item_size_nr(leaf, 0) !=

	    BTRFS_LEAF_DATA_SIZE(fs_info)) {

		CORRUPT("invalid item offset size pair", leaf, root, 0);

		return -EIO;

	}



	/*

	 * Check to make sure each items keys are in the correct order and their

	 * offsets make sense.  We only have to loop through nritems-1 because

	 * we check the current slot against the next slot, which verifies the

	 * next slot's offset+size makes sense and that the current's slot

	 * offset is correct.

	 * Check the following things to make sure this is a good leaf, and

	 * leaf users won't need to bother with similar sanity checks:

	 *

	 * 1) key order

	 * 2) item offset and size

	 *    No overlap, no hole, all inside the leaf.

	 */

	for (slot = 0; slot < nritems - 1; slot++) {

		btrfs_item_key_to_cpu(leaf, &leaf_key, slot);

		btrfs_item_key_to_cpu(leaf, &key, slot + 1);

	for (slot = 0; slot < nritems; slot++) {

		u32 item_end_expected;



		btrfs_item_key_to_cpu(leaf, &key, slot);



		/* Make sure the keys are in the right order */

		if (btrfs_comp_cpu_keys(&leaf_key, &key) >= 0) {

		if (btrfs_comp_cpu_keys(&prev_key, &key) >= 0) {

			CORRUPT("bad key order", leaf, root, slot);

			return -EIO;

			return -EUCLEAN;

		}



		/*
@@ -626,10 +622,14 @@ static noinline int check_leaf(struct btrfs_root *root, 
		 * item data starts at the end of the leaf and grows towards the

		 * front.

		 */

		if (btrfs_item_offset_nr(leaf, slot) !=

			btrfs_item_end_nr(leaf, slot + 1)) {

		if (slot == 0)

			item_end_expected = BTRFS_LEAF_DATA_SIZE(fs_info);

		else

			item_end_expected = btrfs_item_offset_nr(leaf,

								 slot - 1);

		if (btrfs_item_end_nr(leaf, slot) != item_end_expected) {

			CORRUPT("slot offset bad", leaf, root, slot);

			return -EIO;

			return -EUCLEAN;

		}



		/*
@@ -640,8 +640,12 @@ static noinline int check_leaf(struct btrfs_root *root, 
		if (btrfs_item_end_nr(leaf, slot) >

		    BTRFS_LEAF_DATA_SIZE(fs_info)) {

			CORRUPT("slot end outside of leaf", leaf, root, slot);

			return -EIO;

			return -EUCLEAN;

		}



		prev_key.objectid = key.objectid;

		prev_key.type = key.type;

		prev_key.offset = key.offset;

	}



	return 0;

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