1 // SPDX-License-Identifier: GPL-2.0
3  * devtmpfs - kernel-maintained tmpfs-based /dev
8  * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
12  * owned by root and have a default mode of 0600. Subsystems can
47 	struct req *next;  member
51 	umode_t mode;	/* 0 => delete */  member
69 	struct super_block *s = mnt->mnt_sb;  in public_dev_mount()
72 	atomic_inc(&s->s_active);  in public_dev_mount()
73 	down_write(&s->s_umount);  in public_dev_mount()
79 	return dget(s->s_root);  in public_dev_mount()
99 	init_completion(&req->done);  in devtmpfs_submit_req()
102 	req->next = requests;  in devtmpfs_submit_req()
107 	wait_for_completion(&req->done);  in devtmpfs_submit_req()
111 	return req->err;  in devtmpfs_submit_req()
122 	req.mode = 0;  in devtmpfs_create_node()
125 	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);  in devtmpfs_create_node()
127 		return -ENOMEM;  in devtmpfs_create_node()
129 	if (req.mode == 0)  in devtmpfs_create_node()
130 		req.mode = 0600;  in devtmpfs_create_node()
132 		req.mode |= S_IFBLK;  in devtmpfs_create_node()
134 		req.mode |= S_IFCHR;  in devtmpfs_create_node()
151 		return -ENOMEM;  in devtmpfs_delete_node()
153 	req.mode = 0;  in devtmpfs_delete_node()
159 static int dev_mkdir(const char *name, umode_t mode)  in dev_mkdir()  argument
169 	err = vfs_mkdir(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode);  in dev_mkdir()
171 		/* mark as kernel-created inode */  in dev_mkdir()
172 		d_inode(dentry)->i_private = &thread;  in dev_mkdir()
186 		return -ENOMEM;  in create_path()
195 		if (err && err != -EEXIST)  in create_path()
204 static int handle_create(const char *nodename, umode_t mode, kuid_t uid,  in handle_create()  argument
212 	if (dentry == ERR_PTR(-ENOENT)) {  in handle_create()
219 	err = vfs_mknod(&nop_mnt_idmap, d_inode(path.dentry), dentry, mode,  in handle_create()
220 			dev->devt);  in handle_create()
224 		newattrs.ia_mode = mode;  in handle_create()
232 		/* mark as kernel-created inode */  in handle_create()
233 		d_inode(dentry)->i_private = &thread;  in handle_create()
249 		if (d_inode(dentry)->i_private == &thread)  in dev_rmdir()
253 			err = -EPERM;  in dev_rmdir()
255 		err = -ENOENT;  in dev_rmdir()
270 		return -ENOMEM;  in delete_path()
291 	if (inode->i_private != &thread)  in dev_mynode()
296 		if (!S_ISBLK(stat->mode))  in dev_mynode()
299 		if (!S_ISCHR(stat->mode))  in dev_mynode()
302 	if (stat->rdev != dev->devt)  in dev_mynode()
333 			newattrs.ia_mode = stat.mode & ~0777;  in handle_remove()
341 			if (!err || err == -ENOENT)  in handle_remove()
345 		err = -ENOENT;  in handle_remove()
358  * auto-mounted after the kernel mounted the root filesystem.
380 static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,  in handle()  argument
383 	if (mode)  in handle()
384 		return handle_create(name, mode, uid, gid, dev);  in handle()
398 				struct req *next = req->next;  in devtmpfs_work_loop()  local
399 				req->err = handle(req->name, req->mode,  in devtmpfs_work_loop()
400 						  req->uid, req->gid, req->dev);  in devtmpfs_work_loop()
401 				complete(&req->done);  in devtmpfs_work_loop()
402 				req = next;  in devtmpfs_work_loop()
446  * Create devtmpfs instance, driver-core devices will add their device
451 	char opts[] = "mode=0755";  in devtmpfs_init()