btrfs: add assertions for tree == inode->io_tree to extent IO helpers

Add assertions to all helpers that get tree as argument and verify that
it's the same that can be obtained from the inode or from its pages. In
followup patches the redundant arguments and assertions will be removed
one by one.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -3134,6 +3134,8 @@ static int __do_readpage(struct extent_io_tree *tree,
 	size_t blocksize = inode->i_sb->s_blocksize;
 	unsigned long this_bio_flag = 0;
 
+	ASSERT(tree == &BTRFS_I(inode)->io_tree);
+
 	set_page_extent_mapped(page);
 
 	if (!PageUptodate(page)) {
@@ -3327,6 +3329,8 @@ static inline void contiguous_readpages(struct extent_io_tree *tree,
 	struct btrfs_inode *inode = BTRFS_I(pages[0]->mapping->host);
 	int index;
 
+	ASSERT(tree == &inode->io_tree);
+
 	btrfs_lock_and_flush_ordered_range(tree, inode, start, end, NULL);
 
 	for (index = 0; index < nr_pages; index++) {
@@ -3348,6 +3352,8 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
 	u64 end = start + PAGE_SIZE - 1;
 	int ret;
 
+	ASSERT(tree == &inode->io_tree);
+
 	btrfs_lock_and_flush_ordered_range(tree, inode, start, end, NULL);
 
 	ret = __do_readpage(tree, page, get_extent, NULL, bio, mirror_num,
@@ -3362,6 +3368,8 @@ int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
 	unsigned long bio_flags = 0;
 	int ret;
 
+	ASSERT(tree == &BTRFS_I(page->mapping->host)->io_tree);
+
 	ret = __extent_read_full_page(tree, page, get_extent, &bio, mirror_num,
 				      &bio_flags, 0);
 	if (bio)
@@ -5449,6 +5457,8 @@ int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num)
 	if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
 		return 0;
 
+	ASSERT(tree == &BTRFS_I(eb->pages[0]->mapping->host)->io_tree);
+
 	num_pages = num_extent_pages(eb);
 	for (i = 0; i < num_pages; i++) {
 		page = eb->pages[i];

fs/btrfs/ordered-data.c

@@ -854,6 +854,8 @@ void btrfs_lock_and_flush_ordered_range(struct extent_io_tree *tree,
 	struct extent_state *cache = NULL;
 	struct extent_state **cachedp = &cache;
 
+	ASSERT(tree == &inode->io_tree);
+
 	if (cached_state)
 		cachedp = cached_state;