f2fs: support IO error injection

This patch adds to support IO error injection for testing IO error
tolerance of f2fs.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/data.c

@@ -34,6 +34,11 @@ static void f2fs_read_end_io(struct bio *bio)
 	struct bio_vec *bvec;
 	int i;
 
+#ifdef CONFIG_F2FS_FAULT_INJECTION
+	if (time_to_inject(FAULT_IO))
+		bio->bi_error = -EIO;
+#endif
+
 	if (f2fs_bio_encrypted(bio)) {
 		if (bio->bi_error) {
 			fscrypt_release_ctx(bio->bi_private);

fs/f2fs/f2fs.h

@@ -46,6 +46,7 @@ enum {
 	FAULT_BLOCK,
 	FAULT_DIR_DEPTH,
 	FAULT_EVICT_INODE,
+	FAULT_IO,
 	FAULT_MAX,
 };
 
@@ -77,6 +78,8 @@ static inline bool time_to_inject(int type)
 		return false;
 	else if (type == FAULT_EVICT_INODE && !IS_FAULT_SET(type))
 		return false;
+	else if (type == FAULT_IO && !IS_FAULT_SET(type))
+		return false;
 
 	atomic_inc(&f2fs_fault.inject_ops);
 	if (atomic_read(&f2fs_fault.inject_ops) >= f2fs_fault.inject_rate) {

fs/f2fs/super.c

@@ -50,6 +50,7 @@ char *fault_name[FAULT_MAX] = {
 	[FAULT_BLOCK]		= "no more block",
 	[FAULT_DIR_DEPTH]	= "too big dir depth",
 	[FAULT_EVICT_INODE]	= "evict_inode fail",
+	[FAULT_IO]		= "IO error",
 };
 
 static void f2fs_build_fault_attr(unsigned int rate)