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![Linus Torvalds](/assets/img/avatar_default.png)
Pull vfs file system parameter updates from Al Viro: "Saner fs_parser.c guts and data structures. The system-wide registry of syntax types (string/enum/int32/oct32/.../etc.) is gone and so is the horror switch() in fs_parse() that would have to grow another case every time something got added to that system-wide registry. New syntax types can be added by filesystems easily now, and their namespace is that of functions - not of system-wide enum members. IOW, they can be shared or kept private and if some turn out to be widely useful, we can make them common library helpers, etc., without having to do anything whatsoever to fs_parse() itself. And we already get that kind of requests - the thing that finally pushed me into doing that was "oh, and let's add one for timeouts - things like 15s or 2h". If some filesystem really wants that, let them do it. Without somebody having to play gatekeeper for the variants blessed by direct support in fs_parse(), TYVM. Quite a bit of boilerplate is gone. And IMO the data structures make a lot more sense now. -200LoC, while we are at it" * 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (25 commits) tmpfs: switch to use of invalfc() cgroup1: switch to use of errorfc() et.al. procfs: switch to use of invalfc() hugetlbfs: switch to use of invalfc() cramfs: switch to use of errofc() et.al. gfs2: switch to use of errorfc() et.al. fuse: switch to use errorfc() et.al. ceph: use errorfc() and friends instead of spelling the prefix out prefix-handling analogues of errorf() and friends turn fs_param_is_... into functions fs_parse: handle optional arguments sanely fs_parse: fold fs_parameter_desc/fs_parameter_spec fs_parser: remove fs_parameter_description name field add prefix to fs_context->log ceph_parse_param(), ceph_parse_mon_ips(): switch to passing fc_log new primitive: __fs_parse() switch rbd and libceph to p_log-based primitives struct p_log, variants of warnf() et.al. taking that one instead teach logfc() to handle prefices, give it saner calling conventions get rid of cg_invalf() ...
465 lines
9.5 KiB
C
465 lines
9.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* devtmpfs - kernel-maintained tmpfs-based /dev
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*
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* Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
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*
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* During bootup, before any driver core device is registered,
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* devtmpfs, a tmpfs-based filesystem is created. Every driver-core
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* device which requests a device node, will add a node in this
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* filesystem.
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* By default, all devices are named after the name of the device,
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* owned by root and have a default mode of 0600. Subsystems can
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* overwrite the default setting if needed.
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*/
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#include <linux/kernel.h>
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#include <linux/syscalls.h>
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#include <linux/mount.h>
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#include <linux/device.h>
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#include <linux/genhd.h>
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#include <linux/namei.h>
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#include <linux/fs.h>
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#include <linux/shmem_fs.h>
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#include <linux/ramfs.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/kthread.h>
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#include <uapi/linux/mount.h>
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#include "base.h"
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static struct task_struct *thread;
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static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);
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static DEFINE_SPINLOCK(req_lock);
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static struct req {
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struct req *next;
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struct completion done;
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int err;
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const char *name;
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umode_t mode; /* 0 => delete */
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kuid_t uid;
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kgid_t gid;
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struct device *dev;
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} *requests;
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static int __init mount_param(char *str)
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{
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mount_dev = simple_strtoul(str, NULL, 0);
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return 1;
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}
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__setup("devtmpfs.mount=", mount_param);
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static struct vfsmount *mnt;
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static struct dentry *public_dev_mount(struct file_system_type *fs_type, int flags,
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const char *dev_name, void *data)
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{
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struct super_block *s = mnt->mnt_sb;
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atomic_inc(&s->s_active);
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down_write(&s->s_umount);
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return dget(s->s_root);
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}
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static struct file_system_type internal_fs_type = {
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.name = "devtmpfs",
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#ifdef CONFIG_TMPFS
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.init_fs_context = shmem_init_fs_context,
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.parameters = shmem_fs_parameters,
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#else
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.init_fs_context = ramfs_init_fs_context,
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.parameters = ramfs_fs_parameters,
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#endif
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.kill_sb = kill_litter_super,
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};
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static struct file_system_type dev_fs_type = {
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.name = "devtmpfs",
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.mount = public_dev_mount,
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};
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#ifdef CONFIG_BLOCK
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static inline int is_blockdev(struct device *dev)
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{
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return dev->class == &block_class;
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}
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#else
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static inline int is_blockdev(struct device *dev) { return 0; }
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#endif
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static int devtmpfs_submit_req(struct req *req, const char *tmp)
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{
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init_completion(&req->done);
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spin_lock(&req_lock);
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req->next = requests;
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requests = req;
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spin_unlock(&req_lock);
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wake_up_process(thread);
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wait_for_completion(&req->done);
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kfree(tmp);
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return req->err;
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}
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int devtmpfs_create_node(struct device *dev)
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{
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const char *tmp = NULL;
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struct req req;
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if (!thread)
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return 0;
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req.mode = 0;
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req.uid = GLOBAL_ROOT_UID;
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req.gid = GLOBAL_ROOT_GID;
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req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
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if (!req.name)
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return -ENOMEM;
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if (req.mode == 0)
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req.mode = 0600;
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if (is_blockdev(dev))
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req.mode |= S_IFBLK;
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else
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req.mode |= S_IFCHR;
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req.dev = dev;
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return devtmpfs_submit_req(&req, tmp);
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}
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int devtmpfs_delete_node(struct device *dev)
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{
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const char *tmp = NULL;
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struct req req;
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if (!thread)
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return 0;
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req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
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if (!req.name)
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return -ENOMEM;
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req.mode = 0;
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req.dev = dev;
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return devtmpfs_submit_req(&req, tmp);
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}
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static int dev_mkdir(const char *name, umode_t mode)
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{
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struct dentry *dentry;
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struct path path;
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int err;
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dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
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if (IS_ERR(dentry))
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return PTR_ERR(dentry);
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err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
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if (!err)
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/* mark as kernel-created inode */
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d_inode(dentry)->i_private = &thread;
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done_path_create(&path, dentry);
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return err;
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}
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static int create_path(const char *nodepath)
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{
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char *path;
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char *s;
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int err = 0;
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/* parent directories do not exist, create them */
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path = kstrdup(nodepath, GFP_KERNEL);
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if (!path)
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return -ENOMEM;
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s = path;
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for (;;) {
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s = strchr(s, '/');
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if (!s)
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break;
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s[0] = '\0';
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err = dev_mkdir(path, 0755);
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if (err && err != -EEXIST)
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break;
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s[0] = '/';
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s++;
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}
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kfree(path);
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return err;
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}
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static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
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kgid_t gid, struct device *dev)
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{
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struct dentry *dentry;
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struct path path;
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int err;
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dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
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if (dentry == ERR_PTR(-ENOENT)) {
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create_path(nodename);
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dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
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}
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if (IS_ERR(dentry))
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return PTR_ERR(dentry);
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err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
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if (!err) {
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struct iattr newattrs;
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newattrs.ia_mode = mode;
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newattrs.ia_uid = uid;
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newattrs.ia_gid = gid;
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newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
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inode_lock(d_inode(dentry));
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notify_change(dentry, &newattrs, NULL);
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inode_unlock(d_inode(dentry));
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/* mark as kernel-created inode */
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d_inode(dentry)->i_private = &thread;
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}
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done_path_create(&path, dentry);
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return err;
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}
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static int dev_rmdir(const char *name)
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{
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struct path parent;
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struct dentry *dentry;
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int err;
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dentry = kern_path_locked(name, &parent);
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if (IS_ERR(dentry))
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return PTR_ERR(dentry);
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if (d_really_is_positive(dentry)) {
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if (d_inode(dentry)->i_private == &thread)
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err = vfs_rmdir(d_inode(parent.dentry), dentry);
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else
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err = -EPERM;
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} else {
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err = -ENOENT;
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}
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dput(dentry);
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inode_unlock(d_inode(parent.dentry));
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path_put(&parent);
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return err;
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}
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static int delete_path(const char *nodepath)
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{
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char *path;
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int err = 0;
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path = kstrdup(nodepath, GFP_KERNEL);
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if (!path)
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return -ENOMEM;
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for (;;) {
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char *base;
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base = strrchr(path, '/');
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if (!base)
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break;
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base[0] = '\0';
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err = dev_rmdir(path);
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if (err)
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break;
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}
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kfree(path);
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return err;
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}
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static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
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{
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/* did we create it */
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if (inode->i_private != &thread)
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return 0;
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/* does the dev_t match */
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if (is_blockdev(dev)) {
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if (!S_ISBLK(stat->mode))
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return 0;
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} else {
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if (!S_ISCHR(stat->mode))
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return 0;
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}
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if (stat->rdev != dev->devt)
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return 0;
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/* ours */
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return 1;
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}
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static int handle_remove(const char *nodename, struct device *dev)
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{
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struct path parent;
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struct dentry *dentry;
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int deleted = 0;
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int err;
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dentry = kern_path_locked(nodename, &parent);
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if (IS_ERR(dentry))
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return PTR_ERR(dentry);
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if (d_really_is_positive(dentry)) {
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struct kstat stat;
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struct path p = {.mnt = parent.mnt, .dentry = dentry};
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err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
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AT_STATX_SYNC_AS_STAT);
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if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
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struct iattr newattrs;
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/*
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* before unlinking this node, reset permissions
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* of possible references like hardlinks
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*/
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newattrs.ia_uid = GLOBAL_ROOT_UID;
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newattrs.ia_gid = GLOBAL_ROOT_GID;
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newattrs.ia_mode = stat.mode & ~0777;
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newattrs.ia_valid =
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ATTR_UID|ATTR_GID|ATTR_MODE;
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inode_lock(d_inode(dentry));
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notify_change(dentry, &newattrs, NULL);
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inode_unlock(d_inode(dentry));
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err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
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if (!err || err == -ENOENT)
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deleted = 1;
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}
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} else {
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err = -ENOENT;
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}
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dput(dentry);
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inode_unlock(d_inode(parent.dentry));
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path_put(&parent);
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if (deleted && strchr(nodename, '/'))
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delete_path(nodename);
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return err;
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}
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/*
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* If configured, or requested by the commandline, devtmpfs will be
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* auto-mounted after the kernel mounted the root filesystem.
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*/
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int __init devtmpfs_mount(void)
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{
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int err;
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if (!mount_dev)
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return 0;
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if (!thread)
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return 0;
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err = do_mount("devtmpfs", "dev", "devtmpfs", MS_SILENT, NULL);
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if (err)
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printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
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else
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printk(KERN_INFO "devtmpfs: mounted\n");
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return err;
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}
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static DECLARE_COMPLETION(setup_done);
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static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
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struct device *dev)
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{
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if (mode)
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return handle_create(name, mode, uid, gid, dev);
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else
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return handle_remove(name, dev);
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}
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static int devtmpfs_setup(void *p)
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{
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int err;
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err = ksys_unshare(CLONE_NEWNS);
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if (err)
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goto out;
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err = do_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
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if (err)
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goto out;
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ksys_chdir("/.."); /* will traverse into overmounted root */
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ksys_chroot(".");
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out:
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*(int *)p = err;
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complete(&setup_done);
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return err;
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}
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static int devtmpfsd(void *p)
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{
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int err = devtmpfs_setup(p);
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if (err)
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return err;
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while (1) {
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spin_lock(&req_lock);
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while (requests) {
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struct req *req = requests;
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requests = NULL;
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spin_unlock(&req_lock);
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while (req) {
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struct req *next = req->next;
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req->err = handle(req->name, req->mode,
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req->uid, req->gid, req->dev);
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complete(&req->done);
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req = next;
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}
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spin_lock(&req_lock);
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}
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__set_current_state(TASK_INTERRUPTIBLE);
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spin_unlock(&req_lock);
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schedule();
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}
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return 0;
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}
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/*
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* Create devtmpfs instance, driver-core devices will add their device
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* nodes here.
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*/
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int __init devtmpfs_init(void)
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{
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char opts[] = "mode=0755";
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int err;
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mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
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if (IS_ERR(mnt)) {
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printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
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PTR_ERR(mnt));
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return PTR_ERR(mnt);
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}
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err = register_filesystem(&dev_fs_type);
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if (err) {
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printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
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"type %i\n", err);
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return err;
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}
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thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
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if (!IS_ERR(thread)) {
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wait_for_completion(&setup_done);
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} else {
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err = PTR_ERR(thread);
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thread = NULL;
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}
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if (err) {
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printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
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unregister_filesystem(&dev_fs_type);
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return err;
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}
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printk(KERN_INFO "devtmpfs: initialized\n");
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return 0;
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}
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