Commit 99177a34 authored by Tejun Heo's avatar Tejun Heo Committed by Greg Kroah-Hartman
Browse files

kernfs: remove kernfs_addrm_cxt 



kernfs_addrm_cxt and the accompanying kernfs_addrm_start/finish() were
added because there were operations which should be performed outside
kernfs_mutex after adding and removing kernfs_nodes.  The necessary
operations were recorded in kernfs_addrm_cxt and performed by
kernfs_addrm_finish(); however, after the recent changes which
relocated deactivation and unmapping so that they're performed
directly during removal, the only operation kernfs_addrm_finish()
performs is kernfs_put(), which can be moved inside the removal path
too.

This patch moves the kernfs_put() of the base ref to __kernfs_remove()
and remove kernfs_addrm_cxt and kernfs_addrm_start/finish().

* kernfs_add_one() is updated to grab and release the parent's active
  ref and kernfs_mutex itself.  kernfs_get/put_active() and
  kernfs_addrm_start/finish() invocations around it are removed from
  all users.

* __kernfs_remove() puts an unlinked node directly instead of chaining
  it to kernfs_addrm_cxt.  Its callers are updated to grab and release
  kernfs_mutex instead of calling kernfs_addrm_start/finish() around
  it.

v2: Updated to fit the v2 restructuring of removal path.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f601f9a2

fs/kernfs/dir.c

+26 −88
Original line number Diff line number Diff line
@@ -398,29 +398,8 @@ 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

 *
@@ -428,34 +407,29 @@ void kernfs_addrm_start(struct kernfs_addrm_cxt *acxt) 
 *	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_addrm_cxt *acxt, struct kernfs_node *kn,

		  struct kernfs_node *parent)

int kernfs_add_one(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;



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

	if (!kernfs_get_active(parent))

		return -ENOENT;



	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;

	}

	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)

		return -EINVAL;

		goto out_unlock;



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

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


	ret = kernfs_link_sibling(kn);

	if (ret)

		return ret;

		goto out_unlock;



	/* Update timestamps on the parent */

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


	/* Mark the entry added into directory tree */

	atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);

	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() */

	ret = 0;

out_unlock:

	mutex_unlock(&kernfs_mutex);



	/* kill removed kernfs_nodes */

	while (acxt->removed) {

		struct kernfs_node *kn = acxt->removed;



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



		kernfs_put(kn);

	}

	kernfs_put_active(parent);

	return ret;

}



/**
@@ -633,7 +584,6 @@ 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;
@@ -648,14 +598,7 @@ struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, 
	kn->priv = priv;



	/* link in */

	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);

	}



	rc = kernfs_add_one(kn, parent);

	if (!rc)

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

}



static void __kernfs_remove(struct kernfs_addrm_cxt *acxt,

			    struct kernfs_node *kn)

static void __kernfs_remove(struct kernfs_node *kn)

{

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

			}



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

			acxt->removed = pos;

			kernfs_put(pos);

		}



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

void kernfs_remove(struct kernfs_node *kn)

{

	struct kernfs_addrm_cxt acxt;



	kernfs_addrm_start(&acxt);

	__kernfs_remove(&acxt, kn);

	kernfs_addrm_finish(&acxt);

	mutex_lock(&kernfs_mutex);

	__kernfs_remove(kn);

	mutex_unlock(&kernfs_mutex);

}



/**
@@ -925,7 +864,6 @@ 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) {
@@ -934,13 +872,13 @@ int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, 
		return -ENOENT;

	}



	kernfs_addrm_start(&acxt);

	mutex_lock(&kernfs_mutex);



	kn = kernfs_find_ns(parent, name, ns);

	if (kn)

		__kernfs_remove(&acxt, kn);

		__kernfs_remove(kn);



	kernfs_addrm_finish(&acxt);

	mutex_unlock(&kernfs_mutex);



	if (kn)

		return 0;

fs/kernfs/file.c

+1 −9
Original line number Diff line number Diff line
@@ -817,7 +817,6 @@ 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;
@@ -853,14 +852,7 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent, 
	if (ops->mmap)

		kn->flags |= KERNFS_HAS_MMAP;



	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);

	}



	rc = kernfs_add_one(kn, parent);

	if (rc) {

		kernfs_put(kn);

		return ERR_PTR(rc);

fs/kernfs/kernfs-internal.h

+1 −11
Original line number Diff line number Diff line
@@ -45,13 +45,6 @@ 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

 */
@@ -101,10 +94,7 @@ 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);

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);

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

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

				    umode_t mode, unsigned flags);

fs/kernfs/symlink.c

+1 −9
Original line number Diff line number Diff line
@@ -27,7 +27,6 @@ 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,
@@ -40,14 +39,7 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent, 
	kn->symlink.target_kn = target;

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



	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);

	}



	error = kernfs_add_one(kn, parent);

	if (!error)

		return kn;

include/linux/kernfs.h

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

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