kernfs: define kernfs_node_dentry (fb3c8315) · Commits · 戴 / test

fs/kernfs/mount.c

+69 −0

Original line number	Diff line number	Diff line
		@@ -14,6 +14,7 @@
		#include <linux/magic.h>
		#include <linux/slab.h>
		#include <linux/pagemap.h>
		#include <linux/namei.h>

		#include "kernfs-internal.h"

		@@ -62,6 +63,74 @@ struct kernfs_root kernfs_root_from_sb(struct super_block sb)
		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))
		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))
		return ERR_PTR(-EINVAL);
		mutex_lock(&d_inode(dentry)->i_mutex);
		dtmp = lookup_one_len(kntmp->name, dentry, strlen(kntmp->name));
		mutex_unlock(&d_inode(dentry)->i_mutex);
		dput(dentry);
		if (IS_ERR(dtmp))
		return dtmp;
		knparent = kntmp;
		dentry = dtmp;
		} while (true);
		}

		static int kernfs_fill_super(struct super_block *sb, unsigned long magic)
		{
		struct kernfs_super_info *info = kernfs_info(sb);

include/linux/kernfs.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -284,6 +284,8 @@ struct kernfs_node kernfs_node_from_dentry(struct dentry dentry);
		struct kernfs_root kernfs_root_from_sb(struct super_block sb);
		struct inode kernfs_get_inode(struct super_block sb, struct kernfs_node *kn);

		struct dentry kernfs_node_dentry(struct kernfs_node kn,
		struct super_block *sb);
		struct kernfs_root kernfs_create_root(struct kernfs_syscall_ops scops,
		unsigned int flags, void *priv);
		void kernfs_destroy_root(struct kernfs_root *root);

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