fs: constify tree_descr arrays passed to simple_fill_super()

simple_fill_super() is passed an array of tree_descr structures which
describe the files to create in the filesystem's root directory.  Since
these arrays are never modified intentionally, they should be 'const' so
that they are placed in .rodata and benefit from memory protection.
This patch updates the function signature and all users, and also
constifies tree_descr.name.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

drivers/infiniband/hw/qib/qib_fs.c

@@ -512,7 +512,7 @@ static int qibfs_fill_super(struct super_block *sb, void *data, int silent)
 	unsigned long flags;
 	int ret;
 
-	static struct tree_descr files[] = {
+	static const struct tree_descr files[] = {
 		[2] = {"driver_stats", &driver_ops[0], S_IRUGO},
 		[3] = {"driver_stats_names", &driver_ops[1], S_IRUGO},
 		{""},

drivers/xen/xenfs/super.c

@@ -44,14 +44,14 @@ static const struct file_operations capabilities_file_ops = {
 
 static int xenfs_fill_super(struct super_block *sb, void *data, int silent)
 {
-	static struct tree_descr xenfs_files[] = {
+	static const struct tree_descr xenfs_files[] = {
 		[2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
 		{ "capabilities", &capabilities_file_ops, S_IRUGO },
 		{ "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
 		{""},
 	};
 
-	static struct tree_descr xenfs_init_files[] = {
+	static const struct tree_descr xenfs_init_files[] = {
 		[2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
 		{ "capabilities", &capabilities_file_ops, S_IRUGO },
 		{ "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },

fs/binfmt_misc.c

@@ -818,7 +818,7 @@ static const struct super_operations s_ops = {
 static int bm_fill_super(struct super_block *sb, void *data, int silent)
 {
 	int err;
-	static struct tree_descr bm_files[] = {
+	static const struct tree_descr bm_files[] = {
 		[2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
 		[3] = {"register", &bm_register_operations, S_IWUSR},
 		/* last one */ {""}

fs/debugfs/inode.c

@@ -199,7 +199,7 @@ static const struct dentry_operations debugfs_dops = {
 
 static int debug_fill_super(struct super_block *sb, void *data, int silent)
 {
-	static struct tree_descr debug_files[] = {{""}};
+	static const struct tree_descr debug_files[] = {{""}};
 	struct debugfs_fs_info *fsi;
 	int err;
 

fs/fuse/control.c

@@ -292,7 +292,7 @@ void fuse_ctl_remove_conn(struct fuse_conn *fc)
 
 static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
 {
-	struct tree_descr empty_descr = {""};
+	static const struct tree_descr empty_descr = {""};
 	struct fuse_conn *fc;
 	int err;
 

fs/libfs.c

@@ -507,7 +507,7 @@ EXPORT_SYMBOL(simple_write_end);
  * to pass it an appropriate max_reserved value to avoid collisions.
  */
 int simple_fill_super(struct super_block *s, unsigned long magic,
-		      struct tree_descr *files)
+		      const struct tree_descr *files)
 {
 	struct inode *inode;
 	struct dentry *root;

fs/nfsd/nfsctl.c

@@ -1146,7 +1146,7 @@ static ssize_t write_v4_end_grace(struct file *file, char *buf, size_t size)
 
 static int nfsd_fill_super(struct super_block * sb, void * data, int silent)
 {
-	static struct tree_descr nfsd_files[] = {
+	static const struct tree_descr nfsd_files[] = {
 		[NFSD_List] = {"exports", &exports_nfsd_operations, S_IRUGO},
 		[NFSD_Export_features] = {"export_features",
 					&export_features_operations, S_IRUGO},

fs/tracefs/inode.c

@@ -266,7 +266,7 @@ static const struct super_operations tracefs_super_operations = {
 
 static int trace_fill_super(struct super_block *sb, void *data, int silent)
 {
-	static struct tree_descr trace_files[] = {{""}};
+	static const struct tree_descr trace_files[] = {{""}};
 	struct tracefs_fs_info *fsi;
 	int err;
 

include/linux/fs.h

@@ -2995,9 +2995,10 @@ extern const struct file_operations simple_dir_operations;
 extern const struct inode_operations simple_dir_inode_operations;
 extern void make_empty_dir_inode(struct inode *inode);
 extern bool is_empty_dir_inode(struct inode *inode);
-struct tree_descr { char *name; const struct file_operations *ops; int mode; };
+struct tree_descr { const char *name; const struct file_operations *ops; int mode; };
 struct dentry *d_alloc_name(struct dentry *, const char *);
-extern int simple_fill_super(struct super_block *, unsigned long, struct tree_descr *);
+extern int simple_fill_super(struct super_block *, unsigned long,
+			     const struct tree_descr *);
 extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
 extern void simple_release_fs(struct vfsmount **mount, int *count);
 

kernel/bpf/inode.c

@@ -429,7 +429,7 @@ static int bpf_parse_options(char *data, struct bpf_mount_opts *opts)
 
 static int bpf_fill_super(struct super_block *sb, void *data, int silent)
 {
-	static struct tree_descr bpf_rfiles[] = { { "" } };
+	static const struct tree_descr bpf_rfiles[] = { { "" } };
 	struct bpf_mount_opts opts;
 	struct inode *inode;
 	int ret;

security/inode.c

@@ -28,7 +28,7 @@ static int mount_count;
 
 static int fill_super(struct super_block *sb, void *data, int silent)
 {
-	static struct tree_descr files[] = {{""}};
+	static const struct tree_descr files[] = {{""}};
 
 	return simple_fill_super(sb, SECURITYFS_MAGIC, files);
 }

security/selinux/selinuxfs.c

@@ -1496,7 +1496,7 @@ static const struct file_operations sel_avc_cache_stats_ops = {
 static int sel_make_avc_files(struct dentry *dir)
 {
 	int i;
-	static struct tree_descr files[] = {
+	static const struct tree_descr files[] = {
 		{ "cache_threshold",
 		  &sel_avc_cache_threshold_ops, S_IRUGO|S_IWUSR },
 		{ "hash_stats", &sel_avc_hash_stats_ops, S_IRUGO },
@@ -1805,7 +1805,7 @@ static int sel_fill_super(struct super_block *sb, void *data, int silent)
 	struct inode *inode;
 	struct inode_security_struct *isec;
 
-	static struct tree_descr selinux_files[] = {
+	static const struct tree_descr selinux_files[] = {
 		[SEL_LOAD] = {"load", &sel_load_ops, S_IRUSR|S_IWUSR},
 		[SEL_ENFORCE] = {"enforce", &sel_enforce_ops, S_IRUGO|S_IWUSR},
 		[SEL_CONTEXT] = {"context", &transaction_ops, S_IRUGO|S_IWUGO},

security/smack/smackfs.c

@@ -2855,7 +2855,7 @@ static int smk_fill_super(struct super_block *sb, void *data, int silent)
 	int rc;
 	struct inode *root_inode;
 
-	static struct tree_descr smack_files[] = {
+	static const struct tree_descr smack_files[] = {
 		[SMK_LOAD] = {
 			"load", &smk_load_ops, S_IRUGO|S_IWUSR},
 		[SMK_CIPSO] = {