![Thomas Gleixner](/assets/img/avatar_default.png)
Based on 1 normalized pattern(s): this file is released under the gplv2 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 68 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Armijn Hemel <armijn@tjaldur.nl> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190531190114.292346262@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
384 lines
9.5 KiB
C
384 lines
9.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* fs/kernfs/mount.c - kernfs mount implementation
|
|
*
|
|
* Copyright (c) 2001-3 Patrick Mochel
|
|
* Copyright (c) 2007 SUSE Linux Products GmbH
|
|
* Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
|
|
*/
|
|
|
|
#include <linux/fs.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/init.h>
|
|
#include <linux/magic.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/namei.h>
|
|
#include <linux/seq_file.h>
|
|
#include <linux/exportfs.h>
|
|
|
|
#include "kernfs-internal.h"
|
|
|
|
struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache;
|
|
|
|
static int kernfs_sop_show_options(struct seq_file *sf, struct dentry *dentry)
|
|
{
|
|
struct kernfs_root *root = kernfs_root(kernfs_dentry_node(dentry));
|
|
struct kernfs_syscall_ops *scops = root->syscall_ops;
|
|
|
|
if (scops && scops->show_options)
|
|
return scops->show_options(sf, root);
|
|
return 0;
|
|
}
|
|
|
|
static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
|
|
{
|
|
struct kernfs_node *node = kernfs_dentry_node(dentry);
|
|
struct kernfs_root *root = kernfs_root(node);
|
|
struct kernfs_syscall_ops *scops = root->syscall_ops;
|
|
|
|
if (scops && scops->show_path)
|
|
return scops->show_path(sf, node, root);
|
|
|
|
seq_dentry(sf, dentry, " \t\n\\");
|
|
return 0;
|
|
}
|
|
|
|
const struct super_operations kernfs_sops = {
|
|
.statfs = simple_statfs,
|
|
.drop_inode = generic_delete_inode,
|
|
.evict_inode = kernfs_evict_inode,
|
|
|
|
.show_options = kernfs_sop_show_options,
|
|
.show_path = kernfs_sop_show_path,
|
|
};
|
|
|
|
/*
|
|
* Similar to kernfs_fh_get_inode, this one gets kernfs node from inode
|
|
* number and generation
|
|
*/
|
|
struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
|
|
const union kernfs_node_id *id)
|
|
{
|
|
struct kernfs_node *kn;
|
|
|
|
kn = kernfs_find_and_get_node_by_ino(root, id->ino);
|
|
if (!kn)
|
|
return NULL;
|
|
if (kn->id.generation != id->generation) {
|
|
kernfs_put(kn);
|
|
return NULL;
|
|
}
|
|
return kn;
|
|
}
|
|
|
|
static struct inode *kernfs_fh_get_inode(struct super_block *sb,
|
|
u64 ino, u32 generation)
|
|
{
|
|
struct kernfs_super_info *info = kernfs_info(sb);
|
|
struct inode *inode;
|
|
struct kernfs_node *kn;
|
|
|
|
if (ino == 0)
|
|
return ERR_PTR(-ESTALE);
|
|
|
|
kn = kernfs_find_and_get_node_by_ino(info->root, ino);
|
|
if (!kn)
|
|
return ERR_PTR(-ESTALE);
|
|
inode = kernfs_get_inode(sb, kn);
|
|
kernfs_put(kn);
|
|
if (!inode)
|
|
return ERR_PTR(-ESTALE);
|
|
|
|
if (generation && inode->i_generation != generation) {
|
|
/* we didn't find the right inode.. */
|
|
iput(inode);
|
|
return ERR_PTR(-ESTALE);
|
|
}
|
|
return inode;
|
|
}
|
|
|
|
static struct dentry *kernfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
|
|
int fh_len, int fh_type)
|
|
{
|
|
return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
|
|
kernfs_fh_get_inode);
|
|
}
|
|
|
|
static struct dentry *kernfs_fh_to_parent(struct super_block *sb, struct fid *fid,
|
|
int fh_len, int fh_type)
|
|
{
|
|
return generic_fh_to_parent(sb, fid, fh_len, fh_type,
|
|
kernfs_fh_get_inode);
|
|
}
|
|
|
|
static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
|
|
{
|
|
struct kernfs_node *kn = kernfs_dentry_node(child);
|
|
|
|
return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent));
|
|
}
|
|
|
|
static const struct export_operations kernfs_export_ops = {
|
|
.fh_to_dentry = kernfs_fh_to_dentry,
|
|
.fh_to_parent = kernfs_fh_to_parent,
|
|
.get_parent = kernfs_get_parent_dentry,
|
|
};
|
|
|
|
/**
|
|
* kernfs_root_from_sb - determine kernfs_root associated with a super_block
|
|
* @sb: the super_block in question
|
|
*
|
|
* Return the kernfs_root associated with @sb. If @sb is not a kernfs one,
|
|
* %NULL is returned.
|
|
*/
|
|
struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
|
|
{
|
|
if (sb->s_op == &kernfs_sops)
|
|
return kernfs_info(sb)->root;
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find the next ancestor in the path down to @child, where @parent was the
|
|
* ancestor whose descendant we want to find.
|
|
*
|
|
* Say the path is /a/b/c/d. @child is d, @parent is NULL. We return the root
|
|
* node. If @parent is b, then we return the node for c.
|
|
* Passing in d as @parent is not ok.
|
|
*/
|
|
static struct kernfs_node *find_next_ancestor(struct kernfs_node *child,
|
|
struct kernfs_node *parent)
|
|
{
|
|
if (child == parent) {
|
|
pr_crit_once("BUG in find_next_ancestor: called with parent == child");
|
|
return NULL;
|
|
}
|
|
|
|
while (child->parent != parent) {
|
|
if (!child->parent)
|
|
return NULL;
|
|
child = child->parent;
|
|
}
|
|
|
|
return child;
|
|
}
|
|
|
|
/**
|
|
* kernfs_node_dentry - get a dentry for the given kernfs_node
|
|
* @kn: kernfs_node for which a dentry is needed
|
|
* @sb: the kernfs super_block
|
|
*/
|
|
struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
|
|
struct super_block *sb)
|
|
{
|
|
struct dentry *dentry;
|
|
struct kernfs_node *knparent = NULL;
|
|
|
|
BUG_ON(sb->s_op != &kernfs_sops);
|
|
|
|
dentry = dget(sb->s_root);
|
|
|
|
/* Check if this is the root kernfs_node */
|
|
if (!kn->parent)
|
|
return dentry;
|
|
|
|
knparent = find_next_ancestor(kn, NULL);
|
|
if (WARN_ON(!knparent)) {
|
|
dput(dentry);
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
|
|
do {
|
|
struct dentry *dtmp;
|
|
struct kernfs_node *kntmp;
|
|
|
|
if (kn == knparent)
|
|
return dentry;
|
|
kntmp = find_next_ancestor(kn, knparent);
|
|
if (WARN_ON(!kntmp)) {
|
|
dput(dentry);
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
dtmp = lookup_one_len_unlocked(kntmp->name, dentry,
|
|
strlen(kntmp->name));
|
|
dput(dentry);
|
|
if (IS_ERR(dtmp))
|
|
return dtmp;
|
|
knparent = kntmp;
|
|
dentry = dtmp;
|
|
} while (true);
|
|
}
|
|
|
|
static int kernfs_fill_super(struct super_block *sb, struct kernfs_fs_context *kfc)
|
|
{
|
|
struct kernfs_super_info *info = kernfs_info(sb);
|
|
struct inode *inode;
|
|
struct dentry *root;
|
|
|
|
info->sb = sb;
|
|
/* Userspace would break if executables or devices appear on sysfs */
|
|
sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
|
|
sb->s_blocksize = PAGE_SIZE;
|
|
sb->s_blocksize_bits = PAGE_SHIFT;
|
|
sb->s_magic = kfc->magic;
|
|
sb->s_op = &kernfs_sops;
|
|
sb->s_xattr = kernfs_xattr_handlers;
|
|
if (info->root->flags & KERNFS_ROOT_SUPPORT_EXPORTOP)
|
|
sb->s_export_op = &kernfs_export_ops;
|
|
sb->s_time_gran = 1;
|
|
|
|
/* sysfs dentries and inodes don't require IO to create */
|
|
sb->s_shrink.seeks = 0;
|
|
|
|
/* get root inode, initialize and unlock it */
|
|
mutex_lock(&kernfs_mutex);
|
|
inode = kernfs_get_inode(sb, info->root->kn);
|
|
mutex_unlock(&kernfs_mutex);
|
|
if (!inode) {
|
|
pr_debug("kernfs: could not get root inode\n");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/* instantiate and link root dentry */
|
|
root = d_make_root(inode);
|
|
if (!root) {
|
|
pr_debug("%s: could not get root dentry!\n", __func__);
|
|
return -ENOMEM;
|
|
}
|
|
sb->s_root = root;
|
|
sb->s_d_op = &kernfs_dops;
|
|
return 0;
|
|
}
|
|
|
|
static int kernfs_test_super(struct super_block *sb, struct fs_context *fc)
|
|
{
|
|
struct kernfs_super_info *sb_info = kernfs_info(sb);
|
|
struct kernfs_super_info *info = fc->s_fs_info;
|
|
|
|
return sb_info->root == info->root && sb_info->ns == info->ns;
|
|
}
|
|
|
|
static int kernfs_set_super(struct super_block *sb, struct fs_context *fc)
|
|
{
|
|
struct kernfs_fs_context *kfc = fc->fs_private;
|
|
|
|
kfc->ns_tag = NULL;
|
|
return set_anon_super_fc(sb, fc);
|
|
}
|
|
|
|
/**
|
|
* kernfs_super_ns - determine the namespace tag of a kernfs super_block
|
|
* @sb: super_block of interest
|
|
*
|
|
* Return the namespace tag associated with kernfs super_block @sb.
|
|
*/
|
|
const void *kernfs_super_ns(struct super_block *sb)
|
|
{
|
|
struct kernfs_super_info *info = kernfs_info(sb);
|
|
|
|
return info->ns;
|
|
}
|
|
|
|
/**
|
|
* kernfs_get_tree - kernfs filesystem access/retrieval helper
|
|
* @fc: The filesystem context.
|
|
*
|
|
* This is to be called from each kernfs user's fs_context->ops->get_tree()
|
|
* implementation, which should set the specified ->@fs_type and ->@flags, and
|
|
* specify the hierarchy and namespace tag to mount via ->@root and ->@ns,
|
|
* respectively.
|
|
*/
|
|
int kernfs_get_tree(struct fs_context *fc)
|
|
{
|
|
struct kernfs_fs_context *kfc = fc->fs_private;
|
|
struct super_block *sb;
|
|
struct kernfs_super_info *info;
|
|
int error;
|
|
|
|
info = kzalloc(sizeof(*info), GFP_KERNEL);
|
|
if (!info)
|
|
return -ENOMEM;
|
|
|
|
info->root = kfc->root;
|
|
info->ns = kfc->ns_tag;
|
|
INIT_LIST_HEAD(&info->node);
|
|
|
|
fc->s_fs_info = info;
|
|
sb = sget_fc(fc, kernfs_test_super, kernfs_set_super);
|
|
if (IS_ERR(sb))
|
|
return PTR_ERR(sb);
|
|
|
|
if (!sb->s_root) {
|
|
struct kernfs_super_info *info = kernfs_info(sb);
|
|
|
|
kfc->new_sb_created = true;
|
|
|
|
error = kernfs_fill_super(sb, kfc);
|
|
if (error) {
|
|
deactivate_locked_super(sb);
|
|
return error;
|
|
}
|
|
sb->s_flags |= SB_ACTIVE;
|
|
|
|
mutex_lock(&kernfs_mutex);
|
|
list_add(&info->node, &info->root->supers);
|
|
mutex_unlock(&kernfs_mutex);
|
|
}
|
|
|
|
fc->root = dget(sb->s_root);
|
|
return 0;
|
|
}
|
|
|
|
void kernfs_free_fs_context(struct fs_context *fc)
|
|
{
|
|
/* Note that we don't deal with kfc->ns_tag here. */
|
|
kfree(fc->s_fs_info);
|
|
fc->s_fs_info = NULL;
|
|
}
|
|
|
|
/**
|
|
* kernfs_kill_sb - kill_sb for kernfs
|
|
* @sb: super_block being killed
|
|
*
|
|
* This can be used directly for file_system_type->kill_sb(). If a kernfs
|
|
* user needs extra cleanup, it can implement its own kill_sb() and call
|
|
* this function at the end.
|
|
*/
|
|
void kernfs_kill_sb(struct super_block *sb)
|
|
{
|
|
struct kernfs_super_info *info = kernfs_info(sb);
|
|
|
|
mutex_lock(&kernfs_mutex);
|
|
list_del(&info->node);
|
|
mutex_unlock(&kernfs_mutex);
|
|
|
|
/*
|
|
* Remove the superblock from fs_supers/s_instances
|
|
* so we can't find it, before freeing kernfs_super_info.
|
|
*/
|
|
kill_anon_super(sb);
|
|
kfree(info);
|
|
}
|
|
|
|
void __init kernfs_init(void)
|
|
{
|
|
|
|
/*
|
|
* the slab is freed in RCU context, so kernfs_find_and_get_node_by_ino
|
|
* can access the slab lock free. This could introduce stale nodes,
|
|
* please see how kernfs_find_and_get_node_by_ino filters out stale
|
|
* nodes.
|
|
*/
|
|
kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
|
|
sizeof(struct kernfs_node),
|
|
0,
|
|
SLAB_PANIC | SLAB_TYPESAFE_BY_RCU,
|
|
NULL);
|
|
|
|
/* Creates slab cache for kernfs inode attributes */
|
|
kernfs_iattrs_cache = kmem_cache_create("kernfs_iattrs_cache",
|
|
sizeof(struct kernfs_iattrs),
|
|
0, SLAB_PANIC, NULL);
|
|
}
|