f2fs: introduce FAULT_NO_SEGMENT

Use it to simulate no free segment case during block allocation.
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -724,6 +724,7 @@ Description:	Support configuring fault injection type, should be
 		FAULT_LOCK_OP                    0x000020000
 		FAULT_BLKADDR_VALIDITY           0x000040000
 		FAULT_BLKADDR_CONSISTENCE        0x000080000
+		FAULT_NO_SEGMENT                 0x000100000
 		===========================      ===========
 
 What:		/sys/fs/f2fs/<disk>/discard_io_aware_gran

Documentation/filesystems/f2fs.rst

@@ -205,6 +205,7 @@ fault_type=%d		 Support configuring fault injection type, should be
 			 FAULT_LOCK_OP                    0x000020000
 			 FAULT_BLKADDR_VALIDITY           0x000040000
 			 FAULT_BLKADDR_CONSISTENCE        0x000080000
+			 FAULT_NO_SEGMENT                 0x000100000
 			 ===========================      ===========
 mode=%s			 Control block allocation mode which supports "adaptive"
 			 and "lfs". In "lfs" mode, there should be no random

fs/f2fs/f2fs.h

@@ -62,6 +62,7 @@ enum {
 	FAULT_LOCK_OP,
 	FAULT_BLKADDR_VALIDITY,
 	FAULT_BLKADDR_CONSISTENCE,
+	FAULT_NO_SEGMENT,
 	FAULT_MAX,
 };
 

fs/f2fs/segment.c

@@ -2656,6 +2656,11 @@ static int get_new_segment(struct f2fs_sb_info *sbi,
 
 	spin_lock(&free_i->segmap_lock);
 
+	if (time_to_inject(sbi, FAULT_NO_SEGMENT)) {
+		ret = -ENOSPC;
+		goto out_unlock;
+	}
+
 	if (!new_sec && ((*newseg + 1) % SEGS_PER_SEC(sbi))) {
 		segno = find_next_zero_bit(free_i->free_segmap,
 			GET_SEG_FROM_SEC(sbi, hint + 1), *newseg + 1);

fs/f2fs/super.c

@@ -63,6 +63,7 @@ const char *f2fs_fault_name[FAULT_MAX] = {
 	[FAULT_LOCK_OP]			= "lock_op",
 	[FAULT_BLKADDR_VALIDITY]	= "invalid blkaddr",
 	[FAULT_BLKADDR_CONSISTENCE]	= "inconsistent blkaddr",
+	[FAULT_NO_SEGMENT]		= "no free segment",
 };
 
 void f2fs_build_fault_attr(struct f2fs_sb_info *sbi, unsigned int rate,