[PATCH v3 1/2] error-injection: Introduce EI_ETYPE_FALSE for fail_function

[Song Chen <chensong_2000@126.com>]

Introduce EI_ETYPE_FALSE for functions which need false as return
value in their error-injections, like btrfs_data_csum_ok.

EI_ETYPE_NULL can return 0 too but its readability is not good
enough.

Acked-by: David Sterba  <dsterba@suse.com>
Signed-off-by: Song Chen <chensong_2000@126.com>
---
 Documentation/fault-injection/fault-injection.rst | 3 +++
 include/asm-generic/error-injection.h             | 1 +
 kernel/fail_function.c                            | 2 ++
 lib/error-inject.c                                | 2 ++
 4 files changed, 8 insertions(+)

diff --git a/Documentation/fault-injection/fault-injection.rst b/Documentation/fault-injection/fault-injection.rst
index c2d3996b5b40..86431ad2b565 100644
--- a/Documentation/fault-injection/fault-injection.rst
+++ b/Documentation/fault-injection/fault-injection.rst
@@ -347,6 +347,9 @@ EI_ETYPE_ERRNO_NULL
 EI_ETYPE_TRUE
   This function will return `true` (non-zero positive value) if it fails.
 
+EI_ETYPE_FALSE
+  This function will return `false` if it fails.
+
 If you specifies a wrong type, for example, EI_TYPE_ERRNO for the function
 which returns an allocated object, it may cause a problem because the returned
 value is not an object address and the caller can not access to the address.
diff --git a/include/asm-generic/error-injection.h b/include/asm-generic/error-injection.h
index b05253f68eaa..6c399121ab7a 100644
--- a/include/asm-generic/error-injection.h
+++ b/include/asm-generic/error-injection.h
@@ -8,6 +8,7 @@ enum {
 	EI_ETYPE_ERRNO,		/* Return -ERRNO if failure */
 	EI_ETYPE_ERRNO_NULL,	/* Return -ERRNO or NULL if failure */
 	EI_ETYPE_TRUE,		/* Return true if failure */
+	EI_ETYPE_FALSE,		/* Return false if failure */
 };
 
 struct error_injection_entry {
diff --git a/kernel/fail_function.c b/kernel/fail_function.c
index 2eaf55005f49..90cdad0412cd 100644
--- a/kernel/fail_function.c
+++ b/kernel/fail_function.c
@@ -48,6 +48,8 @@ static unsigned long adjust_error_retval(unsigned long addr, unsigned long retv)
 		break;
 	case EI_ETYPE_TRUE:
 		return 1;
+	case EI_ETYPE_FALSE:
+		return 0;
 	}
 
 	return retv;
diff --git a/lib/error-inject.c b/lib/error-inject.c
index 32f3d1ca9ea2..115b10dbf9aa 100644
--- a/lib/error-inject.c
+++ b/lib/error-inject.c
@@ -189,6 +189,8 @@ static const char *error_type_string(int etype)
 		return "ERRNO_NULL";
 	case EI_ETYPE_TRUE:
 		return "TRUE";
+	case EI_ETYPE_FALSE:
+		return "FALSE";
 	default:
 		return "(unknown)";
 	}
-- 
2.43.0