/*! 2016-06-04 study -ing */
static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent,
const unsigned char *name,
const void *ns)
{
struct rb_node *node = parent->dir.children.rb_node;
bool has_ns = kernfs_ns_enabled(parent);
unsigned int hash;
lockdep_assert_held(&kernfs_mutex);
if (has_ns != (bool)ns) {
WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
has_ns ? "required" : "invalid", parent->name, name);
return NULL;
}
/*! name + ns 로 31bit hash 생성하여 return */
hash = kernfs_name_hash(name, ns);
/*! hash 비교해 가면서 원하는 kn을 찾는다. */
while (node) {
struct kernfs_node *kn;
int result;
kn = rb_to_kn(node);
/*! hash 와 kn->hash 비교 */
result = kernfs_name_compare(hash, name, ns, kn);
if (result < 0)
node = node->rb_left;
else if (result > 0)
node = node->rb_right;
else
return kn;
}
return NULL;
}
/**
* kernfs_add_one - add kernfs_node to parent without warning
* @kn: kernfs_node to be added
*
* The caller must already have initialized @kn->parent. This
* function increments nlink of the parent's inode if @kn is a
* directory and link into the children list of the parent.
*
* RETURNS:
* 0 on success, -EEXIST if entry with the given name already
* exists.
*/
int kernfs_add_one(struct kernfs_node *kn)
{
struct kernfs_node *parent = kn->parent;
struct kernfs_iattrs *ps_iattr;
bool has_ns;
int ret;
mutex_lock(&kernfs_mutex);
ret = -EINVAL;
has_ns = kernfs_ns_enabled(parent);
if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
has_ns ? "required" : "invalid", parent->name, kn->name))
goto out_unlock;
if (kernfs_type(parent) != KERNFS_DIR)
goto out_unlock;
ret = -ENOENT;
if (parent->flags & KERNFS_EMPTY_DIR)
goto out_unlock;
if ((parent->flags & KERNFS_ACTIVATED) && !kernfs_active(parent))
goto out_unlock;
kn->hash = kernfs_name_hash(kn->name, kn->ns);
ret = kernfs_link_sibling(kn);
if (ret)
goto out_unlock;
/* Update timestamps on the parent */
ps_iattr = parent->iattr;
if (ps_iattr) {
struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
ktime_get_real_ts(&ps_iattrs->ia_ctime);
ps_iattrs->ia_mtime = ps_iattrs->ia_ctime;
}
mutex_unlock(&kernfs_mutex);
/*
* Activate the new node unless CREATE_DEACTIVATED is requested.
* If not activated here, the kernfs user is responsible for
* activating the node with kernfs_activate(). A node which hasn't
* been activated is not visible to userland and its removal won't
* trigger deactivation.
*/
if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED))
kernfs_activate(kn);
return 0;
out_unlock:
mutex_unlock(&kernfs_mutex);
return ret;
}
static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
{
struct kernfs_node *kn;
if (flags & LOOKUP_RCU)
return -ECHILD;
/* Always perform fresh lookup for negatives */
if (!dentry->d_inode)
goto out_bad_unlocked;
kn = dentry->d_fsdata;
mutex_lock(&kernfs_mutex);
/* The kernfs node has been deleted */
if (kn->flags & KERNFS_REMOVED)
goto out_bad;
/* The kernfs node has been moved? */
if (dentry->d_parent->d_fsdata != kn->parent)
goto out_bad;
/* The kernfs node has been renamed */
if (strcmp(dentry->d_name.name, kn->name) != 0)
goto out_bad;
/* The kernfs node has been moved to a different namespace */
if (kn->parent && kernfs_ns_enabled(kn->parent) &&
kernfs_info(dentry->d_sb)->ns != kn->ns)
goto out_bad;
mutex_unlock(&kernfs_mutex);
out_valid:
return 1;
out_bad:
mutex_unlock(&kernfs_mutex);
out_bad_unlocked:
/*
* @dentry doesn't match the underlying kernfs node, drop the
* dentry and force lookup. If we have submounts we must allow the
* vfs caches to lie about the state of the filesystem to prevent
* leaks and other nasty things, so use check_submounts_and_drop()
* instead of d_drop().
*/
if (check_submounts_and_drop(dentry) != 0)
goto out_valid;
return 0;
}
/**
* sysfs_delete_link - remove symlink in object's directory.
* @kobj: object we're acting for.
* @targ: object we're pointing to.
* @name: name of the symlink to remove.
*
* Unlike sysfs_remove_link sysfs_delete_link has enough information
* to successfully delete symlinks in tagged directories.
*/
void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
const char *name)
{
const void *ns = NULL;
/*
* We don't own @target and it may be removed at any time.
* Synchronize using sysfs_symlink_target_lock. See
* sysfs_remove_dir() for details.
*/
spin_lock(&sysfs_symlink_target_lock);
if (targ->sd && kernfs_ns_enabled(kobj->sd))
ns = targ->sd->ns;
spin_unlock(&sysfs_symlink_target_lock);
kernfs_remove_by_name_ns(kobj->sd, name, ns);
}
static struct dentry *kernfs_iop_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags)
{
struct dentry *ret;
struct kernfs_node *parent = dentry->d_parent->d_fsdata;
struct kernfs_node *kn;
struct inode *inode;
const void *ns = NULL;
mutex_lock(&kernfs_mutex);
if (kernfs_ns_enabled(parent))
ns = kernfs_info(dir->i_sb)->ns;
kn = kernfs_find_ns(parent, dentry->d_name.name, ns);
/* no such entry */
if (!kn) {
ret = NULL;
goto out_unlock;
}
kernfs_get(kn);
dentry->d_fsdata = kn;
/* attach dentry and inode */
inode = kernfs_get_inode(dir->i_sb, kn);
if (!inode) {
ret = ERR_PTR(-ENOMEM);
goto out_unlock;
}
/* instantiate and hash dentry */
ret = d_materialise_unique(dentry, inode);
out_unlock:
mutex_unlock(&kernfs_mutex);
return ret;
}
static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
{
struct kernfs_node *kn;
if (flags & LOOKUP_RCU)
return -ECHILD;
/* Always perform fresh lookup for negatives */
if (d_really_is_negative(dentry))
goto out_bad_unlocked;
kn = dentry->d_fsdata;
mutex_lock(&kernfs_mutex);
/* The kernfs node has been deactivated */
if (!kernfs_active(kn))
goto out_bad;
/* The kernfs node has been moved? */
if (dentry->d_parent->d_fsdata != kn->parent)
goto out_bad;
/* The kernfs node has been renamed */
if (strcmp(dentry->d_name.name, kn->name) != 0)
goto out_bad;
/* The kernfs node has been moved to a different namespace */
if (kn->parent && kernfs_ns_enabled(kn->parent) &&
kernfs_info(dentry->d_sb)->ns != kn->ns)
goto out_bad;
mutex_unlock(&kernfs_mutex);
return 1;
out_bad:
mutex_unlock(&kernfs_mutex);
out_bad_unlocked:
return 0;
}
/**
* kernfs_create_link - create a symlink
* @parent: directory to create the symlink in
* @name: name of the symlink
* @target: target node for the symlink to point to
*
* Returns the created node on success, ERR_PTR() value on error.
*/
struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
const char *name,
struct kernfs_node *target)
{
struct kernfs_node *kn;
int error;
kn = kernfs_new_node(parent, name, S_IFLNK|S_IRWXUGO, KERNFS_LINK);
if (!kn)
return ERR_PTR(-ENOMEM);
if (kernfs_ns_enabled(parent))
kn->ns = target->ns;
kn->symlink.target_kn = target;
kernfs_get(target); /* ref owned by symlink */
error = kernfs_add_one(kn);
if (!error)
return kn;
kernfs_put(kn);
return ERR_PTR(error);
}
/*! 2017. 8.12 study -ing */
int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn)
{
struct kernfs_node *parent = kn->parent;
bool has_ns = kernfs_ns_enabled(parent);
struct kernfs_iattrs *ps_iattr;
int ret;
if (has_ns != (bool)kn->ns) {
WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n",
has_ns ? "required" : "invalid", parent->name, kn->name);
return -EINVAL;
}
if (kernfs_type(parent) != KERNFS_DIR)
return -EINVAL;
if (parent->flags & KERNFS_REMOVED)
return -ENOENT;
kn->hash = kernfs_name_hash(kn->name, kn->ns);
ret = kernfs_link_sibling(kn);
if (ret)
return ret;
/* Update timestamps on the parent */
ps_iattr = parent->iattr;
if (ps_iattr) {
struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
}
/* Mark the entry added into directory tree */
kn->flags &= ~KERNFS_REMOVED;
return 0;
}
static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
{
struct dentry *dentry = file->f_path.dentry;
struct kernfs_node *parent = dentry->d_fsdata;
struct kernfs_node *pos = file->private_data;
const void *ns = NULL;
if (!dir_emit_dots(file, ctx))
return 0;
mutex_lock(&kernfs_mutex);
if (kernfs_ns_enabled(parent))
ns = kernfs_info(dentry->d_sb)->ns;
for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos);
pos;
pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) {
const char *name = pos->name;
unsigned int type = dt_type(pos);
int len = strlen(name);
ino_t ino = pos->ino;
ctx->pos = pos->hash;
file->private_data = pos;
kernfs_get(pos);
mutex_unlock(&kernfs_mutex);
if (!dir_emit(ctx, name, len, ino, type))
return 0;
mutex_lock(&kernfs_mutex);
}
mutex_unlock(&kernfs_mutex);
file->private_data = NULL;
ctx->pos = INT_MAX;
return 0;
}