Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 851cd173 authored by Liu Bo's avatar Liu Bo Committed by David Sterba
Browse files

Btrfs: memset to avoid stale content in btree leaf 



This is an additional patch to
"Btrfs: memset to avoid stale content in btree node block".

This uses memset to initialize the unused space in a leaf to avoid
potential stale content, which may be incurred by pushing items
between sibling leaves.

Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 0f5053eb

fs/btrfs/ctree.c

+0 −14
Original line number Diff line number Diff line
@@ -1715,20 +1715,6 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans, 
	return err;

}



/*

 * The leaf data grows from end-to-front in the node.

 * this returns the address of the start of the last item,

 * which is the stop of the leaf data stack

 */

static inline unsigned int leaf_data_end(struct btrfs_root *root,

					 struct extent_buffer *leaf)

{

	u32 nr = btrfs_header_nritems(leaf);

	if (nr == 0)

		return BTRFS_LEAF_DATA_SIZE(root);

	return btrfs_item_offset_nr(leaf, nr - 1);

}





/*

 * search for key in the extent_buffer.  The items start at offset p,

fs/btrfs/ctree.h

+15 −0
Original line number Diff line number Diff line
@@ -2293,6 +2293,21 @@ static inline unsigned long btrfs_leaf_data(struct extent_buffer *l) 
	return offsetof(struct btrfs_leaf, items);

}



/*

 * The leaf data grows from end-to-front in the node.

 * this returns the address of the start of the last item,

 * which is the stop of the leaf data stack

 */

static inline unsigned int leaf_data_end(struct btrfs_root *root,

					 struct extent_buffer *leaf)

{

	u32 nr = btrfs_header_nritems(leaf);



	if (nr == 0)

		return BTRFS_LEAF_DATA_SIZE(root);

	return btrfs_item_offset_nr(leaf, nr - 1);

}



/* struct btrfs_file_extent_item */

BTRFS_SETGET_FUNCS(file_extent_type, struct btrfs_file_extent_item, type, 8);

BTRFS_SETGET_STACK_FUNCS(stack_file_extent_disk_bytenr,

fs/btrfs/extent_io.c

+13 −5
Original line number Diff line number Diff line
@@ -3725,8 +3725,10 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb, 
	struct block_device *bdev = fs_info->fs_devices->latest_bdev;

	struct extent_io_tree *tree = &BTRFS_I(fs_info->btree_inode)->io_tree;

	u64 offset = eb->start;

	u32 nritems;

	unsigned long i, num_pages;

	unsigned long bio_flags = 0;

	unsigned long start, end;

	int write_flags = (epd->sync_io ? WRITE_SYNC : 0) | REQ_META;

	int ret = 0;
@@ -3736,15 +3738,21 @@ static noinline_for_stack int write_one_eb(struct extent_buffer *eb, 
	if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID)

		bio_flags = EXTENT_BIO_TREE_LOG;



	/* set btree node beyond nritems with 0 to avoid stale content */

	if (btrfs_header_level(eb) > 0) {

		u32 nritems;

		unsigned long end;



	/* set btree blocks beyond nritems with 0 to avoid stale content. */

	nritems = btrfs_header_nritems(eb);

	if (btrfs_header_level(eb) > 0) {

		end = btrfs_node_key_ptr_offset(nritems);



		memset_extent_buffer(eb, 0, end, eb->len - end);

	} else {

		/*

		 * leaf:

		 * header 0 1 2 .. N ... data_N .. data_2 data_1 data_0

		 */

		start = btrfs_item_nr_offset(nritems);

		end = btrfs_leaf_data(eb) +

		      leaf_data_end(fs_info->tree_root, eb);

		memset_extent_buffer(eb, 0, start, end - start);

	}



	for (i = 0; i < num_pages; i++) {