f2fs: fix m_may_create to make OPU DIO write correctly

Previously, we added a parameter @map.m_may_create to trigger OPU
allocation and call f2fs_balance_fs() correctly.

But in get_more_blocks(), @create has been overwritten by below code.
So the function f2fs_map_blocks() will not allocate new block address
but directly go out. Meanwile,there are several functions calling
f2fs_map_blocks() directly and @map.m_may_create not initialized.
CODE:
create = dio->op == REQ_OP_WRITE;
	if (dio->flags & DIO_SKIP_HOLES) {
		if (fs_startblk <= ((i_size_read(dio->inode) - 1) >>
						i_blkbits))
			create = 0;
	}

This patch fixes it.
Signed-off-by: Jia Zhu <zhujia13@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -1035,6 +1035,10 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
 	end = pgofs + maxblocks;
 
 	if (!create && f2fs_lookup_extent_cache(inode, pgofs, &ei)) {
+		if (test_opt(sbi, LFS) && flag == F2FS_GET_BLOCK_DIO &&
+							map->m_may_create)
+			goto next_dnode;
+
 		map->m_pblk = ei.blk + pgofs - ei.fofs;
 		map->m_len = min((pgoff_t)maxblocks, ei.fofs + ei.len - pgofs);
 		map->m_flags = F2FS_MAP_MAPPED;
@@ -1246,6 +1250,7 @@ bool f2fs_overwrite_io(struct inode *inode, loff_t pos, size_t len)
 	map.m_next_pgofs = NULL;
 	map.m_next_extent = NULL;
 	map.m_seg_type = NO_CHECK_TYPE;
+	map.m_may_create = false;
 	last_lblk = F2FS_BLK_ALIGN(pos + len);
 
 	while (map.m_lblk < last_lblk) {

fs/f2fs/file.c

@@ -2201,7 +2201,8 @@ static int f2fs_defragment_range(struct f2fs_sb_info *sbi,
 {
 	struct inode *inode = file_inode(filp);
 	struct f2fs_map_blocks map = { .m_next_extent = NULL,
-					.m_seg_type = NO_CHECK_TYPE };
+					.m_seg_type = NO_CHECK_TYPE ,
+					.m_may_create = false };
 	struct extent_info ei = {0, 0, 0};
 	pgoff_t pg_start, pg_end, next_pgofs;
 	unsigned int blk_per_seg = sbi->blocks_per_seg;
@@ -2935,6 +2936,7 @@ int f2fs_precache_extents(struct inode *inode)
 	map.m_next_pgofs = NULL;
 	map.m_next_extent = &m_next_extent;
 	map.m_seg_type = NO_CHECK_TYPE;
+	map.m_may_create = false;
 	end = F2FS_I_SB(inode)->max_file_blocks;
 
 	while (map.m_lblk < end) {