f2fs: init local extent_info to avoid stale stack info in tp

To avoid such stale(fops, blk, len) info in f2fs_lookup_extent_tree_end tp

dio-23095 [005] ...1 17878.856859: f2fs_lookup_extent_tree_end:
			dev = (259,30), ino = 856, pgofs = 0,
			ext_info(fofs: 3441207040, blk: 4294967232, len: 3481143808)
Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -511,7 +511,7 @@ int f2fs_reserve_block(struct dnode_of_data *dn, pgoff_t index)
 
 int f2fs_get_block(struct dnode_of_data *dn, pgoff_t index)
 {
-	struct extent_info ei;
+	struct extent_info ei  = {0,0,0};
 	struct inode *inode = dn->inode;
 
 	if (f2fs_lookup_extent_cache(inode, index, &ei)) {
@@ -528,7 +528,7 @@ struct page *get_read_data_page(struct inode *inode, pgoff_t index,
 	struct address_space *mapping = inode->i_mapping;
 	struct dnode_of_data dn;
 	struct page *page;
-	struct extent_info ei;
+	struct extent_info ei = {0,0,0};
 	int err;
 	struct f2fs_io_info fio = {
 		.sbi = F2FS_I_SB(inode),
@@ -803,7 +803,7 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
 	int err = 0, ofs = 1;
 	unsigned int ofs_in_node, last_ofs_in_node;
 	blkcnt_t prealloc;
-	struct extent_info ei;
+	struct extent_info ei = {0,0,0};
 	block_t blkaddr;
 
 	if (!maxblocks)
@@ -1667,7 +1667,7 @@ static int prepare_write_begin(struct f2fs_sb_info *sbi,
 	struct dnode_of_data dn;
 	struct page *ipage;
 	bool locked = false;
-	struct extent_info ei;
+	struct extent_info ei = {0,0,0};
 	int err = 0;
 
 	/*

fs/f2fs/file.c

@@ -1877,7 +1877,7 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
 {
 	struct inode *inode = file_inode(filp);
 	struct f2fs_map_blocks map = { .m_next_pgofs = NULL };
-	struct extent_info ei;
+	struct extent_info ei = {0,0,0};
 	pgoff_t pg_start, pg_end;
 	unsigned int blk_per_seg = sbi->blocks_per_seg;
 	unsigned int total = 0, sec_num;