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Commit 7653fe9d authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
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Revert "kernfs: remove kernfs_addrm_cxt" 



This reverts commit 99177a34.

Tejun writes:
        I'm sorry but can you please revert the whole series?
        get_active() waiting while a node is deactivated has potential
        to lead to deadlock and that deactivate/reactivate interface is
        something fundamentally flawed and that cgroup will have to work
        with the remove_self() like everybody else.  IOW, I think the
        first posting was correct.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f4b3e631

fs/kernfs/dir.c

+88 −26
Original line number Diff line number Diff line
@@ -398,8 +398,29 @@ struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name, 
	return NULL;

}



/**

 *	kernfs_addrm_start - prepare for kernfs_node add/remove

 *	@acxt: pointer to kernfs_addrm_cxt to be used

 *

 *	This function is called when the caller is about to add or remove

 *	kernfs_node.  This function acquires kernfs_mutex.  @acxt is used

 *	to keep and pass context to other addrm functions.

 *

 *	LOCKING:

 *	Kernel thread context (may sleep).  kernfs_mutex is locked on

 *	return.

 */

void kernfs_addrm_start(struct kernfs_addrm_cxt *acxt)

	__acquires(kernfs_mutex)

{

	memset(acxt, 0, sizeof(*acxt));



	mutex_lock(&kernfs_mutex);

}



/**

 *	kernfs_add_one - add kernfs_node to parent without warning

 *	@acxt: addrm context to use

 *	@kn: kernfs_node to be added

 *	@parent: the parent kernfs_node to add @kn to

 *
@@ -407,29 +428,34 @@ struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name, 
 *	parent inode if @kn is a directory and link into the children list

 *	of the parent.

 *

 *	This function should be called between calls to

 *	kernfs_addrm_start() and kernfs_addrm_finish() and should be passed

 *	the same @acxt as passed to kernfs_addrm_start().

 *

 *	LOCKING:

 *	Determined by kernfs_addrm_start().

 *

 *	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)

int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn,

		  struct kernfs_node *parent)

{

	bool has_ns = kernfs_ns_enabled(parent);

	struct kernfs_iattrs *ps_iattr;

	bool has_ns;

	int ret;



	if (!kernfs_get_active(parent))

		return -ENOENT;



	mutex_lock(&kernfs_mutex);

	WARN_ON_ONCE(atomic_read(&parent->active) < 0);



	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 (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)

		goto out_unlock;

		return -EINVAL;



	kn->hash = kernfs_name_hash(kn->name, kn->ns);

	kn->parent = parent;
@@ -437,7 +463,7 @@ int kernfs_add_one(struct kernfs_node *kn, struct kernfs_node *parent) 


	ret = kernfs_link_sibling(kn);

	if (ret)

		goto out_unlock;

		return ret;



	/* Update timestamps on the parent */

	ps_iattr = parent->iattr;
@@ -448,11 +474,34 @@ int kernfs_add_one(struct kernfs_node *kn, struct kernfs_node *parent) 


	/* Mark the entry added into directory tree */

	atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);

	ret = 0;

out_unlock:

	return 0;

}



/**

 *	kernfs_addrm_finish - finish up kernfs_node add/remove

 *	@acxt: addrm context to finish up

 *

 *	Finish up kernfs_node add/remove.  Resources acquired by

 *	kernfs_addrm_start() are released and removed kernfs_nodes are

 *	cleaned up.

 *

 *	LOCKING:

 *	kernfs_mutex is released.

 */

void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt)

	__releases(kernfs_mutex)

{

	/* release resources acquired by kernfs_addrm_start() */

	mutex_unlock(&kernfs_mutex);

	kernfs_put_active(parent);

	return ret;



	/* kill removed kernfs_nodes */

	while (acxt->removed) {

		struct kernfs_node *kn = acxt->removed;



		acxt->removed = kn->u.removed_list;



		kernfs_put(kn);

	}

}



/**
@@ -584,6 +633,7 @@ struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, 
					 const char *name, umode_t mode,

					 void *priv, const void *ns)

{

	struct kernfs_addrm_cxt acxt;

	struct kernfs_node *kn;

	int rc;
@@ -598,7 +648,14 @@ struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, 
	kn->priv = priv;



	/* link in */

	rc = kernfs_add_one(kn, parent);

	rc = -ENOENT;

	if (kernfs_get_active(parent)) {

		kernfs_addrm_start(&acxt);

		rc = kernfs_add_one(&acxt, kn, parent);

		kernfs_addrm_finish(&acxt);

		kernfs_put_active(parent);

	}



	if (!rc)

		return kn;
@@ -784,7 +841,8 @@ static void __kernfs_deactivate(struct kernfs_node *kn) 
	}

}



static void __kernfs_remove(struct kernfs_node *kn)

static void __kernfs_remove(struct kernfs_addrm_cxt *acxt,

			    struct kernfs_node *kn)

{

	struct kernfs_node *pos;
@@ -832,7 +890,8 @@ static void __kernfs_remove(struct kernfs_node *kn) 
				ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME;

			}



			kernfs_put(pos);

			pos->u.removed_list = acxt->removed;

			acxt->removed = pos;

		}



		kernfs_put(pos);
@@ -847,9 +906,11 @@ static void __kernfs_remove(struct kernfs_node *kn) 
 */

void kernfs_remove(struct kernfs_node *kn)

{

	mutex_lock(&kernfs_mutex);

	__kernfs_remove(kn);

	mutex_unlock(&kernfs_mutex);

	struct kernfs_addrm_cxt acxt;



	kernfs_addrm_start(&acxt);

	__kernfs_remove(&acxt, kn);

	kernfs_addrm_finish(&acxt);

}



/**
@@ -864,6 +925,7 @@ void kernfs_remove(struct kernfs_node *kn) 
int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,

			     const void *ns)

{

	struct kernfs_addrm_cxt acxt;

	struct kernfs_node *kn;



	if (!parent) {
@@ -872,13 +934,13 @@ int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, 
		return -ENOENT;

	}



	mutex_lock(&kernfs_mutex);

	kernfs_addrm_start(&acxt);



	kn = kernfs_find_ns(parent, name, ns);

	if (kn)

		__kernfs_remove(kn);

		__kernfs_remove(&acxt, kn);



	mutex_unlock(&kernfs_mutex);

	kernfs_addrm_finish(&acxt);



	if (kn)

		return 0;

fs/kernfs/file.c

+9 −1
Original line number Diff line number Diff line
@@ -817,6 +817,7 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent, 
					 bool name_is_static,

					 struct lock_class_key *key)

{

	struct kernfs_addrm_cxt acxt;

	struct kernfs_node *kn;

	unsigned flags;

	int rc;
@@ -852,7 +853,14 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent, 
	if (ops->mmap)

		kn->flags |= KERNFS_HAS_MMAP;



	rc = kernfs_add_one(kn, parent);

	rc = -ENOENT;

	if (kernfs_get_active(parent)) {

		kernfs_addrm_start(&acxt);

		rc = kernfs_add_one(&acxt, kn, parent);

		kernfs_addrm_finish(&acxt);

		kernfs_put_active(parent);

	}



	if (rc) {

		kernfs_put(kn);

		return ERR_PTR(rc);

fs/kernfs/kernfs-internal.h

+11 −1
Original line number Diff line number Diff line
@@ -45,6 +45,13 @@ static inline struct kernfs_root *kernfs_root(struct kernfs_node *kn) 
	return kn->dir.root;

}



/*

 * Context structure to be used while adding/removing nodes.

 */

struct kernfs_addrm_cxt {

	struct kernfs_node	*removed;

};



/*

 * mount.c

 */
@@ -94,7 +101,10 @@ extern const struct inode_operations kernfs_dir_iops; 


struct kernfs_node *kernfs_get_active(struct kernfs_node *kn);

void kernfs_put_active(struct kernfs_node *kn);

int kernfs_add_one(struct kernfs_node *kn, struct kernfs_node *parent);

void kernfs_addrm_start(struct kernfs_addrm_cxt *acxt);

int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn,

		   struct kernfs_node *parent);

void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt);

struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name,

				    umode_t mode, unsigned flags);

fs/kernfs/symlink.c

+9 −1
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent, 
				       struct kernfs_node *target)

{

	struct kernfs_node *kn;

	struct kernfs_addrm_cxt acxt;

	int error;



	kn = kernfs_new_node(kernfs_root(parent), name, S_IFLNK|S_IRWXUGO,
@@ -39,7 +40,14 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent, 
	kn->symlink.target_kn = target;

	kernfs_get(target);	/* ref owned by symlink */



	error = kernfs_add_one(kn, parent);

	error = -ENOENT;

	if (kernfs_get_active(parent)) {

		kernfs_addrm_start(&acxt);

		error = kernfs_add_one(&acxt, kn, parent);

		kernfs_addrm_finish(&acxt);

		kernfs_put_active(parent);

	}



	if (!error)

		return kn;

include/linux/kernfs.h

+4 −0
Original line number Diff line number Diff line
@@ -89,6 +89,10 @@ struct kernfs_node { 


	struct rb_node		rb;



	union {

		struct kernfs_node	*removed_list;

	} u;



	const void		*ns;	/* namespace tag */

	unsigned int		hash;	/* ns + name hash */

	union {