f2fs: introduce FAULT_SKIP_WRITE

In order to simulate skipped write during enable_checkpoint().

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -744,6 +744,7 @@ Description:	Support configuring fault injection type, should be
 		FAULT_ATOMIC_TIMEOUT             0x00400000 (1000ms)
 		FAULT_VMALLOC                    0x00800000
 		FAULT_LOCK_TIMEOUT               0x01000000 (1000ms)
+		FAULT_SKIP_WRITE                 0x02000000
 		===========================      ==========
 
 What:		/sys/fs/f2fs/<disk>/discard_io_aware_gran

Documentation/filesystems/f2fs.rst

@@ -218,6 +218,7 @@ fault_type=%d		 Support configuring fault injection type, should be
 			     FAULT_ATOMIC_TIMEOUT             0x00400000 (1000ms)
 			     FAULT_VMALLOC                    0x00800000
 			     FAULT_LOCK_TIMEOUT               0x01000000 (1000ms)
+			     FAULT_SKIP_WRITE                 0x02000000
 			     ===========================      ==========
 mode=%s			 Control block allocation mode which supports "adaptive"
 			 and "lfs". In "lfs" mode, there should be no random

fs/f2fs/data.c

@@ -2921,6 +2921,10 @@ int f2fs_do_write_data_page(struct f2fs_io_info *fio)
 		goto got_it;
 	}
 
+	if (is_sbi_flag_set(fio->sbi, SBI_ENABLE_CHECKPOINT) &&
+		time_to_inject(fio->sbi, FAULT_SKIP_WRITE))
+		return -EINVAL;
+
 	/* Deadlock due to between page->lock and f2fs_lock_op */
 	if (fio->need_lock == LOCK_REQ && !f2fs_trylock_op(fio->sbi, &lc))
 		return -EAGAIN;

fs/f2fs/f2fs.h

@@ -66,6 +66,7 @@ enum {
 	FAULT_ATOMIC_TIMEOUT,
 	FAULT_VMALLOC,
 	FAULT_LOCK_TIMEOUT,
+	FAULT_SKIP_WRITE,
 	FAULT_MAX,
 };
 

fs/f2fs/super.c

@@ -70,6 +70,7 @@ const char *f2fs_fault_name[FAULT_MAX] = {
 	[FAULT_ATOMIC_TIMEOUT]		= "atomic timeout",
 	[FAULT_VMALLOC]			= "vmalloc",
 	[FAULT_LOCK_TIMEOUT]		= "lock timeout",
+	[FAULT_SKIP_WRITE]		= "skip write",
 };
 
 int f2fs_build_fault_attr(struct f2fs_sb_info *sbi, unsigned long rate,