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: a46bebd502fe ("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 5a37d6f4943555ef57fc16016872f713818f0b2a)
Signed-off-by: zhoudan8 <zhoudan8@xiaomi.com>

fs/f2fs/file.c

@@ -2064,7 +2064,11 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
 		clear_inode_flag(fi->cow_inode, FI_INLINE_DATA);
 	} else {
 		/* Reuse the already created COW inode */
-		f2fs_do_truncate_blocks(fi->cow_inode, 0, true);
+		ret = f2fs_do_truncate_blocks(fi->cow_inode, 0, true);
+		if (ret) {
+			f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
+			goto out;
+		}
 	}
 
 	f2fs_write_inode(inode, NULL);