Merge tag 'pull-f_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull file->f_path constification from Al Viro:
 "Only one thing was modifying ->f_path of an opened file - acct(2).

  Massaging that away and constifying a bunch of struct path * arguments
  in functions that might be given &file->f_path ends up with the
  situation where we can turn ->f_path into an anon union of const
  struct path f_path and struct path __f_path, the latter modified only
  in a few places in fs/{file_table,open,namei}.c, all for struct file
  instances that are yet to be opened"

* tag 'pull-f_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (23 commits)
  Have cc(1) catch attempts to modify ->f_path
  kernel/acct.c: saner struct file treatment
  configfs:get_target() - release path as soon as we grab configfs_item reference
  apparmor/af_unix: constify struct path * arguments
  ovl_is_real_file: constify realpath argument
  ovl_sync_file(): constify path argument
  ovl_lower_dir(): constify path argument
  ovl_get_verity_digest(): constify path argument
  ovl_validate_verity(): constify {meta,data}path arguments
  ovl_ensure_verity_loaded(): constify datapath argument
  ksmbd_vfs_set_init_posix_acl(): constify path argument
  ksmbd_vfs_inherit_posix_acl(): constify path argument
  ksmbd_vfs_kern_path_unlock(): constify path argument
  ksmbd_vfs_path_lookup_locked(): root_share_path can be const struct path *
  check_export(): constify path argument
  export_operations->open(): constify path argument
  rqst_exp_get_by_name(): constify path argument
  nfs: constify path argument of __vfs_getattr()
  bpf...d_path(): constify path argument
  done_path_create(): constify path argument
  ...

Author: torvalds

fs/bpf_fs_kfuncs.c

@@ -79,7 +79,7 @@ __bpf_kfunc void bpf_put_file(struct file *file)
  * pathname in *buf*, including the NUL termination character. On error, a
  * negative integer is returned.
  */
-__bpf_kfunc int bpf_path_d_path(struct path *path, char *buf, size_t buf__sz)
+__bpf_kfunc int bpf_path_d_path(const struct path *path, char *buf, size_t buf__sz)
 {
 	int len;
 	char *ret;

fs/configfs/symlink.c

@@ -114,34 +114,28 @@ static int create_link(struct config_item *parent_item,
 }
 
 
-static int get_target(const char *symname, struct path *path,
-		      struct config_item **target, struct super_block *sb)
+static int get_target(const char *symname, struct config_item **target,
+		      struct super_block *sb)
 {
+	struct path path __free(path_put) = {};
 	int ret;
 
-	ret = kern_path(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, path);
-	if (!ret) {
-		if (path->dentry->d_sb == sb) {
-			*target = configfs_get_config_item(path->dentry);
-			if (!*target) {
-				ret = -ENOENT;
-				path_put(path);
-			}
-		} else {
-			ret = -EPERM;
-			path_put(path);
-		}
-	}
-
-	return ret;
+	ret = kern_path(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &path);
+	if (ret)
+		return ret;
+	if (path.dentry->d_sb != sb)
+		return -EPERM;
+	*target = configfs_get_config_item(path.dentry);
+	if (!*target)
+		return -ENOENT;
+	return 0;
 }
 
 
 int configfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 		     struct dentry *dentry, const char *symname)
 {
 	int ret;
-	struct path path;
 	struct configfs_dirent *sd;
 	struct config_item *parent_item;
 	struct config_item *target_item = NULL;
@@ -188,7 +182,7 @@ int configfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 	 *  AV, a thoroughly annoyed bastard.
 	 */
 	inode_unlock(dir);
-	ret = get_target(symname, &path, &target_item, dentry->d_sb);
+	ret = get_target(symname, &target_item, dentry->d_sb);
 	inode_lock(dir);
 	if (ret)
 		goto out_put;
@@ -210,7 +204,6 @@ int configfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 	}
 
 	config_item_put(target_item);
-	path_put(&path);
 
 out_put:
 	config_item_put(parent_item);

fs/file_table.c

@@ -54,7 +54,7 @@ struct backing_file {
 
 #define backing_file(f) container_of(f, struct backing_file, file)
 
-struct path *backing_file_user_path(const struct file *f)
+const struct path *backing_file_user_path(const struct file *f)
 {
 	return &backing_file(f)->user_path;
 }
@@ -171,7 +171,7 @@ static int init_file(struct file *f, int flags, const struct cred *cred)
 	 * the respective member when opening the file.
 	 */
 	mutex_init(&f->f_pos_lock);
-	memset(&f->f_path, 0, sizeof(f->f_path));
+	memset(&f->__f_path, 0, sizeof(f->f_path));
 	memset(&f->f_ra, 0, sizeof(f->f_ra));
 
 	f->f_flags	= flags;
@@ -319,7 +319,7 @@ struct file *alloc_empty_backing_file(int flags, const struct cred *cred)
 static void file_init_path(struct file *file, const struct path *path,
 			   const struct file_operations *fop)
 {
-	file->f_path = *path;
+	file->__f_path = *path;
 	file->f_inode = path->dentry->d_inode;
 	file->f_mapping = path->dentry->d_inode->i_mapping;
 	file->f_wb_err = filemap_sample_wb_err(file->f_mapping);

fs/internal.h

@@ -53,7 +53,7 @@ extern int finish_clean_context(struct fs_context *fc);
  * namei.c
  */
 extern int filename_lookup(int dfd, struct filename *name, unsigned flags,
-			   struct path *path, struct path *root);
+			   struct path *path, const struct path *root);
 int do_rmdir(int dfd, struct filename *name);
 int do_unlinkat(int dfd, struct filename *name);
 int may_linkat(struct mnt_idmap *idmap, const struct path *link);

fs/namei.c

@@ -2695,7 +2695,7 @@ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path
 }
 
 int filename_lookup(int dfd, struct filename *name, unsigned flags,
-		    struct path *path, struct path *root)
+		    struct path *path, const struct path *root)
 {
 	int retval;
 	struct nameidata nd;
@@ -3651,8 +3651,8 @@ static struct dentry *atomic_open(struct nameidata *nd, struct dentry *dentry,
 	if (nd->flags & LOOKUP_DIRECTORY)
 		open_flag |= O_DIRECTORY;
 
-	file->f_path.dentry = DENTRY_NOT_SET;
-	file->f_path.mnt = nd->path.mnt;
+	file->__f_path.dentry = DENTRY_NOT_SET;
+	file->__f_path.mnt = nd->path.mnt;
 	error = dir->i_op->atomic_open(dir, dentry, file,
 				       open_to_namei_flags(open_flag), mode);
 	d_lookup_done(dentry);
@@ -4020,8 +4020,8 @@ int vfs_tmpfile(struct mnt_idmap *idmap,
 	child = d_alloc(parentpath->dentry, &slash_name);
 	if (unlikely(!child))
 		return -ENOMEM;
-	file->f_path.mnt = parentpath->mnt;
-	file->f_path.dentry = child;
+	file->__f_path.mnt = parentpath->mnt;
+	file->__f_path.dentry = child;
 	mode = vfs_prepare_mode(idmap, dir, mode, mode, mode);
 	error = dir->i_op->tmpfile(idmap, dir, file, mode);
 	dput(child);
@@ -4256,7 +4256,7 @@ struct dentry *start_creating_path(int dfd, const char *pathname,
 }
 EXPORT_SYMBOL(start_creating_path);
 
-void end_creating_path(struct path *path, struct dentry *dentry)
+void end_creating_path(const struct path *path, struct dentry *dentry)
 {
 	if (!IS_ERR(dentry))
 		dput(dentry);

fs/nfs/localio.c

@@ -676,7 +676,7 @@ nfs_set_local_verifier(struct inode *inode,
 }
 
 /* Factored out from fs/nfsd/vfs.h:fh_getattr() */
-static int __vfs_getattr(struct path *p, struct kstat *stat, int version)
+static int __vfs_getattr(const struct path *p, struct kstat *stat, int version)
 {
 	u32 request_mask = STATX_BASIC_STATS;
 

fs/nfsd/export.c

@@ -402,7 +402,7 @@ static struct svc_export *svc_export_update(struct svc_export *new,
 					    struct svc_export *old);
 static struct svc_export *svc_export_lookup(struct svc_export *);
 
-static int check_export(struct path *path, int *flags, unsigned char *uuid)
+static int check_export(const struct path *path, int *flags, unsigned char *uuid)
 {
 	struct inode *inode = d_inode(path->dentry);
 
@@ -1181,7 +1181,7 @@ __be32 check_nfsd_access(struct svc_export *exp, struct svc_rqst *rqstp,
  * use exp_get_by_name() or exp_find().
  */
 struct svc_export *
-rqst_exp_get_by_name(struct svc_rqst *rqstp, struct path *path)
+rqst_exp_get_by_name(struct svc_rqst *rqstp, const struct path *path)
 {
 	struct svc_export *gssexp, *exp = ERR_PTR(-ENOENT);
 	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

fs/nfsd/export.h

@@ -111,7 +111,7 @@ int			nfsd_export_init(struct net *);
 void			nfsd_export_shutdown(struct net *);
 void			nfsd_export_flush(struct net *);
 struct svc_export *	rqst_exp_get_by_name(struct svc_rqst *,
-					     struct path *);
+					     const struct path *);
 struct svc_export *	rqst_exp_parent(struct svc_rqst *,
 					struct path *);
 struct svc_export *	rqst_find_fsidzero_export(struct svc_rqst *);

fs/nsfs.c

@@ -571,7 +571,7 @@ static int nsfs_export_permission(struct handle_to_path_ctx *ctx,
 	return 0;
 }
 
-static struct file *nsfs_export_open(struct path *path, unsigned int oflags)
+static struct file *nsfs_export_open(const struct path *path, unsigned int oflags)
 {
 	return file_open_root(path, "", oflags, 0);
 }

fs/open.c

@@ -1022,8 +1022,8 @@ static int do_dentry_open(struct file *f,
 	put_file_access(f);
 cleanup_file:
 	path_put(&f->f_path);
-	f->f_path.mnt = NULL;
-	f->f_path.dentry = NULL;
+	f->__f_path.mnt = NULL;
+	f->__f_path.dentry = NULL;
 	f->f_inode = NULL;
 	return error;
 }
@@ -1050,7 +1050,7 @@ int finish_open(struct file *file, struct dentry *dentry,
 {
 	BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
 
-	file->f_path.dentry = dentry;
+	file->__f_path.dentry = dentry;
 	return do_dentry_open(file, open);
 }
 EXPORT_SYMBOL(finish_open);
@@ -1073,7 +1073,7 @@ int finish_no_open(struct file *file, struct dentry *dentry)
 {
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
-	file->f_path.dentry = dentry;
+	file->__f_path.dentry = dentry;
 	return 0;
 }
 EXPORT_SYMBOL(finish_no_open);
@@ -1093,7 +1093,7 @@ int vfs_open(const struct path *path, struct file *file)
 {
 	int ret;
 
-	file->f_path = *path;
+	file->__f_path = *path;
 	ret = do_dentry_open(file, NULL);
 	if (!ret) {
 		/*