f2fs: fix to map blocks correctly for direct write

f2fs_map_blocks() supports to map continuous holes or preallocated
address, we should avoid setting F2FS_MAP_MAPPED for these cases
only, otherwise, it may fail f2fs_iomap_begin(), and make direct
write fallbacking to use buffered IO and flush, result in performance
regression.

Fixes: 9f0f6bf ("f2fs: support to map continuous holes or preallocated address")
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-lkp/[email protected]
Cc: Cyril Hrubis <[email protected]>
Signed-off-by: Chao Yu <[email protected]>
Signed-off-by: Jaegeuk Kim <[email protected]>

Author: chaseyu

fs/f2fs/data.c

@@ -1676,7 +1676,8 @@ int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map, int flag)
 		/* reserved delalloc block should be mapped for fiemap. */
 		if (blkaddr == NEW_ADDR)
 			map->m_flags |= F2FS_MAP_DELALLOC;
-		if (flag != F2FS_GET_BLOCK_DIO || !is_hole)
+		/* DIO READ and hole case, should not map the blocks. */
+		if (!(flag == F2FS_GET_BLOCK_DIO && is_hole && !map->m_may_create))
 			map->m_flags |= F2FS_MAP_MAPPED;
 
 		map->m_pblk = blkaddr;