resize.f2fs: skip cursegs when finding next free block

resize.f2fs: skip cursegs when finding next free block

resize.f2fs (f2fs_defragment) tries to migrate blocks to new positions.
However, if a curseg is selected, and f2fs_defragment is broken by any
error, curseg->next_blkoff is left not updated.

To avoid this, we skip cursegs when finding next free block.

Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>