ext4: add nonstring annotations to ext4.h

This suppresses some false positives in gcc 8's -Wstringop-truncation

Suggested by Miguel Ojeda (hopefully the __nonstring definition will
eventually get accepted in the compiler-gcc.h header file).

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 1fc013f3d944..249bcee4d7b2 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -43,6 +43,17 @@
 #define __FS_HAS_ENCRYPTION IS_ENABLED(CONFIG_EXT4_FS_ENCRYPTION)
 #include <linux/fscrypt.h>
 
+#include <linux/compiler.h>
+
+/* Until this gets included into linux/compiler-gcc.h */
+#ifndef __nonstring
+#if defined(GCC_VERSION) && (GCC_VERSION >= 80000)
+#define __nonstring __attribute__((nonstring))
+#else
+#define __nonstring
+#endif
+#endif
+
 /*
  * The fourth extended filesystem constants/structures
  */
@@ -1226,7 +1237,7 @@ struct ext4_super_block {
         __le32  s_feature_ro_compat;    /* readonly-compatible feature set */
 /*68*/  __u8    s_uuid[16];             /* 128-bit uuid for volume */
 /*78*/  char    s_volume_name[16];      /* volume name */
-/*88*/  char    s_last_mounted[64];     /* directory where last mounted */
+/*88*/  char    s_last_mounted[64] __nonstring; /* directory where last mounted */
 /*C8*/  __le32  s_algorithm_usage_bitmap; /* For compression */
         /*
          * Performance hints.  Directory preallocation should only
@@ -1277,13 +1288,13 @@ struct ext4_super_block {
         __le32  s_first_error_time;     /* first time an error happened */
         __le32  s_first_error_ino;      /* inode involved in first error */
         __le64  s_first_error_block;    /* block involved of first error */
-        __u8    s_first_error_func[32]; /* function where the error happened */
+        __u8    s_first_error_func[32] __nonstring;     /* function where the error happened */
         __le32  s_first_error_line;     /* line number where error happened */
         __le32  s_last_error_time;      /* most recent time of an error */
         __le32  s_last_error_ino;       /* inode involved in last error */
         __le32  s_last_error_line;      /* line number where error happened */
         __le64  s_last_error_block;     /* block involved of last error */
-        __u8    s_last_error_func[32];  /* function where the error happened */
+        __u8    s_last_error_func[32] __nonstring;      /* function where the error happened */
 #define EXT4_S_ERR_END offsetof(struct ext4_super_block, s_mount_opts)
         __u8    s_mount_opts[64];
         __le32  s_usr_quota_inum;       /* inode for tracking user quota */