f2fs: support fault injection for f2fs_is_valid_blkaddr()

This patch supports to inject fault into f2fs_is_valid_blkaddr() to
simulate accessing inconsistent data/meta block addressses from caller.

Usage:
a) echo 262144 > /sys/fs/f2fs/<dev>/inject_type or
b) mount -o fault_type=262144 <dev> <mountpoint>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/filesystems/f2fs.rst

@@ -199,6 +199,7 @@ fault_type=%d		 Support configuring fault injection type, should be
 			 FAULT_SLAB_ALLOC	  0x000008000
 			 FAULT_DQUOT_INIT	  0x000010000
 			 FAULT_LOCK_OP		  0x000020000
+			 FAULT_BLKADDR		  0x000040000
 			 ===================	  ===========
 mode=%s			 Control block allocation mode which supports "adaptive"
 			 and "lfs". In "lfs" mode, there should be no random

fs/f2fs/checkpoint.c

@@ -171,6 +171,11 @@ static bool __is_bitmap_valid(struct f2fs_sb_info *sbi, block_t blkaddr,
 bool f2fs_is_valid_blkaddr(struct f2fs_sb_info *sbi,
 					block_t blkaddr, int type)
 {
+	if (time_to_inject(sbi, FAULT_BLKADDR)) {
+		f2fs_show_injection_info(sbi, FAULT_BLKADDR);
+		return false;
+	}
+
 	switch (type) {
 	case META_NAT:
 		break;

fs/f2fs/f2fs.h

@@ -60,6 +60,7 @@ enum {
 	FAULT_SLAB_ALLOC,
 	FAULT_DQUOT_INIT,
 	FAULT_LOCK_OP,
+	FAULT_BLKADDR,
 	FAULT_MAX,
 };
 

fs/f2fs/super.c

@@ -61,6 +61,7 @@ const char *f2fs_fault_name[FAULT_MAX] = {
 	[FAULT_SLAB_ALLOC]	= "slab alloc",
 	[FAULT_DQUOT_INIT]	= "dquot initialize",
 	[FAULT_LOCK_OP]		= "lock_op",
+	[FAULT_BLKADDR]		= "invalid blkaddr",
 };
 
 void f2fs_build_fault_attr(struct f2fs_sb_info *sbi, unsigned int rate,