dm: constify argument arrays

The arrays of 'struct dm_arg' are never modified by the device-mapper
core, so constify them so that they are placed in .rodata.

(Exception: the args array in dm-raid cannot be constified because it is
allocated on the stack and modified.)

Signed-off-by: Eric Biggers <[e-mail]>
Signed-off-by: Mike Snitzer <[e-mail]>

drivers/md/dm-cache-target.c

···
 static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
 			  char **error)
 {
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, 2, "Invalid number of cache feature arguments"},
 	};
 
···
 static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
 			char **error)
 {
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, 1024, "Invalid number of policy arguments"},
 	};
 

drivers/md/dm-crypt.c

···
 {
 	struct crypt_config *cc = ti->private;
 	struct dm_arg_set as;
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, 6, "Invalid number of feature args"},
 	};
 	unsigned int opt_params, val;

drivers/md/dm-flakey.c

···
 	unsigned argc;
 	const char *arg_name;
 
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, 6, "Invalid number of feature args"},
 		{1, UINT_MAX, "Invalid corrupt bio byte"},
 		{0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
···
  */
 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, UINT_MAX, "Invalid up interval"},
 		{0, UINT_MAX, "Invalid down interval"},
 	};

drivers/md/dm-integrity.c

···
 	int r;
 	unsigned extra_args;
 	struct dm_arg_set as;
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, 9, "Invalid number of feature args"},
 	};
 	unsigned journal_sectors, interleave_sectors, buffer_sectors, journal_watermark, sync_msec;

drivers/md/dm-mpath.c

···
 	struct path_selector_type *pst;
 	unsigned ps_argc;
 
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, 1024, "invalid number of path selector args"},
 	};
 
···
 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
 						   struct multipath *m)
 {
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{1, 1024, "invalid number of paths"},
 		{0, 1024, "invalid number of selector args"}
 	};
···
 	int ret;
 	struct dm_target *ti = m->ti;
 
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, 1024, "invalid number of hardware handler args"},
 	};
 
···
 	struct dm_target *ti = m->ti;
 	const char *arg_name;
 
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, 8, "invalid number of feature args"},
 		{1, 50, "pg_init_retries must be between 1 and 50"},
 		{0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
···
 static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
 {
 	/* target arguments */
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, 1024, "invalid number of priority groups"},
 		{0, 1024, "invalid initial priority group number"},
 	};

drivers/md/dm-switch.c

···
  */
 static int switch_ctr(struct dm_target *ti, unsigned argc, char **argv)
 {
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{1, (KMALLOC_MAX_SIZE - sizeof(struct switch_ctx)) / sizeof(struct switch_path), "Invalid number of paths"},
 		{1, UINT_MAX, "Invalid region size"},
 		{0, 0, "Invalid number of optional args"},

drivers/md/dm-table.c

···
 /*
  * Target argument parsing helpers.
  */
-static int validate_next_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
+static int validate_next_arg(const struct dm_arg *arg,
+			     struct dm_arg_set *arg_set,
 			     unsigned *value, char **error, unsigned grouped)
 {
 	const char *arg_str = dm_shift_arg(arg_set);
···
 	return 0;
 }
 
-int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
+int dm_read_arg(const struct dm_arg *arg, struct dm_arg_set *arg_set,
 		unsigned *value, char **error)
 {
 	return validate_next_arg(arg, arg_set, value, error, 0);
 }
 EXPORT_SYMBOL(dm_read_arg);
 
-int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
+int dm_read_arg_group(const struct dm_arg *arg, struct dm_arg_set *arg_set,
 		      unsigned *value, char **error)
 {
 	return validate_next_arg(arg, arg_set, value, error, 1);

drivers/md/dm-thin.c

···
 	unsigned argc;
 	const char *arg_name;
 
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, 4, "Invalid number of pool feature arguments"},
 	};
 

drivers/md/dm-verity-target.c

···
 	struct dm_target *ti = v->ti;
 	const char *arg_name;
 
-	static struct dm_arg _args[] = {
+	static const struct dm_arg _args[] = {
 		{0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
 	};
 

include/linux/device-mapper.h

···
  * Validate the next argument, either returning it as *value or, if invalid,
  * returning -EINVAL and setting *error.
  */
-int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
+int dm_read_arg(const struct dm_arg *arg, struct dm_arg_set *arg_set,
 		unsigned *value, char **error);
 
 /*
···
  * arg->min and arg->max further arguments. Either return the size as
  * *num_args or, if invalid, return -EINVAL and set *error.
  */
-int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
+int dm_read_arg_group(const struct dm_arg *arg, struct dm_arg_set *arg_set,
 		      unsigned *num_args, char **error);
 
 /*