f2fs: support fault injection to f2fs_trylock_op()

f2fs: support fault injection for f2fs_trylock_op()

This patch supports to inject fault into f2fs_trylock_op().

Usage:
a) echo 65536 > /sys/fs/f2fs/<dev>/inject_type or
b) mount -o fault_type=65536 <dev> <mountpoint>

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

Author: chaseyu

Documentation/filesystems/f2fs.rst

@@ -198,6 +198,7 @@ fault_type=%d		 Support configuring fault injection type, should be
 			 FAULT_WRITE_IO		  0x000004000
 			 FAULT_SLAB_ALLOC	  0x000008000
 			 FAULT_DQUOT_INIT	  0x000010000
+			 FAULT_LOCK_OP		  0x000020000
 			 ===================	  ===========
 mode=%s			 Control block allocation mode which supports "adaptive"
 			 and "lfs". In "lfs" mode, there should be no random

fs/f2fs/f2fs.h

@@ -56,6 +56,7 @@ enum {
 	FAULT_WRITE_IO,
 	FAULT_SLAB_ALLOC,
 	FAULT_DQUOT_INIT,
+	FAULT_LOCK_OP,
 	FAULT_MAX,
 };
 
@@ -2095,6 +2096,10 @@ static inline void f2fs_lock_op(struct f2fs_sb_info *sbi)
 
 static inline int f2fs_trylock_op(struct f2fs_sb_info *sbi)
 {
+	if (time_to_inject(sbi, FAULT_LOCK_OP)) {
+		f2fs_show_injection_info(sbi, FAULT_LOCK_OP);
+		return 0;
+	}
 	return down_read_trylock(&sbi->cp_rwsem);
 }
 

fs/f2fs/super.c

@@ -59,6 +59,7 @@ const char *f2fs_fault_name[FAULT_MAX] = {
 	[FAULT_WRITE_IO]	= "write IO error",
 	[FAULT_SLAB_ALLOC]	= "slab alloc",
 	[FAULT_DQUOT_INIT]	= "dquot initialize",
+	[FAULT_LOCK_OP]		= "lock_op",
 };
 
 void f2fs_build_fault_attr(struct f2fs_sb_info *sbi, unsigned int rate,