kernfs: add exportfs operations (aa818825) · Commits · 戴 / test

fs/kernfs/mount.c

+56 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,7 @@
		#include <linux/pagemap.h>
		#include <linux/namei.h>
		#include <linux/seq_file.h>
		#include <linux/exportfs.h>

		#include "kernfs-internal.h"

		@@ -64,6 +65,59 @@ const struct super_operations kernfs_sops = {
		.show_path = kernfs_sop_show_path,
		};

		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 (IS_ERR(inode))
		return ERR_CAST(inode);

		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
		@@ -159,6 +213,8 @@ static int kernfs_fill_super(struct super_block *sb, unsigned long magic)
		sb->s_magic = 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;

		/* get root inode, initialize and unlock it */

include/linux/kernfs.h

+12 −0

Original line number	Diff line number	Diff line
		@@ -69,6 +69,12 @@ enum kernfs_root_flag {
		* following flag enables that behavior.
		*/
		KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK = 0x0002,

		/*
		* The filesystem supports exportfs operation, so userspace can use
		* fhandle to access nodes of the fs.
		*/
		KERNFS_ROOT_SUPPORT_EXPORTOP = 0x0004,
		};

		/* type-specific structures for kernfs_node union members */
		@@ -98,6 +104,12 @@ struct kernfs_elem_attr {
		/* represent a kernfs node */
		union kernfs_node_id {
		struct {
		/*
		* blktrace will export this struct as a simplified 'struct
		* fid' (which is a big data struction), so userspace can use
		* it to find kernfs node. The layout must match the first two
		* fields of 'struct fid' exactly.
		*/
		u32 ino;
		u32 generation;
		};

kernel/cgroup/cgroup.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1737,7 +1737,8 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask, int ref_flags)
		&cgroup_kf_syscall_ops : &cgroup1_kf_syscall_ops;

		root->kf_root = kernfs_create_root(kf_sops,
		KERNFS_ROOT_CREATE_DEACTIVATED,
		KERNFS_ROOT_CREATE_DEACTIVATED \|
		KERNFS_ROOT_SUPPORT_EXPORTOP,
		root_cgrp);
		if (IS_ERR(root->kf_root)) {
		ret = PTR_ERR(root->kf_root);

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