BACKPORT: f2fs: fix to check return value of f2fs_do_truncate_blocks()

Otherwise, if truncation on cow_inode failed, remained data may
pollute current transaction of atomic write.

Bug: 298879042
Cc: Daeho Jeong <daehojeong@google.com>
Fixes: a46bebd5 ("f2fs: synchronize atomic write aborts")
Change-Id: I964ef3e57b0f0dbf77ec4cc8f9cbf349c2a01fff
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
(cherry picked from commit 5a37d6f4)
Signed-off-by: zhoudan8 <zhoudan8@xiaomi.com>