Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 798c75a0 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
Browse files

Revert "kernfs: remove KERNFS_REMOVED" 



This reverts commit ae34372e.

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 4f4b1b64

fs/kernfs/dir.c

+35 −44
Original line number Diff line number Diff line
@@ -127,7 +127,6 @@ static void kernfs_unlink_sibling(struct kernfs_node *kn) 
		kn->parent->dir.subdirs--;



	rb_erase(&kn->rb, &kn->parent->dir.children);

	RB_CLEAR_NODE(&kn->rb);

}



/**
@@ -178,16 +177,18 @@ void kernfs_put_active(struct kernfs_node *kn) 
}



/**

 * kernfs_drain - drain kernfs_node

 * @kn: kernfs_node to drain

 *	kernfs_deactivate - deactivate kernfs_node

 *	@kn: kernfs_node to deactivate

 *

 * Drain existing usages.

 *	Deny new active references and drain existing ones.

 */

static void kernfs_drain(struct kernfs_node *kn)

static void kernfs_deactivate(struct kernfs_node *kn)

{

	struct kernfs_root *root = kernfs_root(kn);



	WARN_ON_ONCE(atomic_read(&kn->active) >= 0);

	BUG_ON(!(kn->flags & KERNFS_REMOVED));



	atomic_add(KN_DEACTIVATED_BIAS, &kn->active);



	if (kernfs_lockdep(kn)) {

		rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_);
@@ -232,15 +233,13 @@ void kernfs_put(struct kernfs_node *kn) 
		return;

	root = kernfs_root(kn);

 repeat:

	/*

	 * Moving/renaming is always done while holding reference.

	/* Moving/renaming is always done while holding reference.

	 * kn->parent won't change beneath us.

	 */

	parent = kn->parent;



	WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS,

		  "kernfs_put: %s/%s: released with incorrect active_ref %d\n",

		  parent ? parent->name : "", kn->name, atomic_read(&kn->active));

	WARN(!(kn->flags & KERNFS_REMOVED), "kernfs: free using entry: %s/%s\n",

	     parent ? parent->name : "", kn->name);



	if (kernfs_type(kn) == KERNFS_LINK)

		kernfs_put(kn->symlink.target_kn);
@@ -282,8 +281,8 @@ static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) 
	kn = dentry->d_fsdata;

	mutex_lock(&kernfs_mutex);



	/* Force fresh lookup if removed */

	if (kn->parent && RB_EMPTY_NODE(&kn->rb))

	/* The kernfs node has been deleted */

	if (kn->flags & KERNFS_REMOVED)

		goto out_bad;



	/* The kernfs node has been moved? */
@@ -351,12 +350,11 @@ struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name, 
	kn->ino = ret;



	atomic_set(&kn->count, 1);

	atomic_set(&kn->active, KN_DEACTIVATED_BIAS);

	RB_CLEAR_NODE(&kn->rb);

	atomic_set(&kn->active, 0);



	kn->name = name;

	kn->mode = mode;

	kn->flags = flags;

	kn->flags = flags | KERNFS_REMOVED;



	return kn;
@@ -415,8 +413,6 @@ int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn, 
	struct kernfs_iattrs *ps_iattr;

	int ret;



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



	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);
@@ -426,6 +422,9 @@ int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn, 
	if (kernfs_type(parent) != KERNFS_DIR)

		return -EINVAL;



	if (parent->flags & KERNFS_REMOVED)

		return -ENOENT;



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

	kn->parent = parent;

	kernfs_get(parent);
@@ -442,7 +441,8 @@ 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);

	kn->flags &= ~KERNFS_REMOVED;



	return 0;

}
@@ -470,7 +470,7 @@ static void kernfs_remove_one(struct kernfs_addrm_cxt *acxt, 
	 * Removal can be called multiple times on the same node.  Only the

	 * first invocation is effective and puts the base ref.

	 */

	if (atomic_read(&kn->active) < 0)

	if (kn->flags & KERNFS_REMOVED)

		return;



	if (kn->parent) {
@@ -484,7 +484,7 @@ static void kernfs_remove_one(struct kernfs_addrm_cxt *acxt, 
		}

	}



	atomic_add(KN_DEACTIVATED_BIAS, &kn->active);

	kn->flags |= KERNFS_REMOVED;

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

	acxt->removed = kn;

}
@@ -512,7 +512,7 @@ void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt) 


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



		kernfs_drain(kn);

		kernfs_deactivate(kn);

		kernfs_unmap_bin_file(kn);

		kernfs_put(kn);

	}
@@ -610,7 +610,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv) 
		return ERR_PTR(-ENOMEM);

	}



	atomic_sub(KN_DEACTIVATED_BIAS, &kn->active);

	kn->flags &= ~KERNFS_REMOVED;

	kn->priv = priv;

	kn->dir.root = root;
@@ -662,13 +662,9 @@ 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);

	}



	if (!rc)

		return kn;
@@ -903,29 +899,27 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, 
{

	int error;



	mutex_lock(&kernfs_mutex);



	error = -ENOENT;

	if (!kernfs_get_active(new_parent))

	if ((kn->flags | new_parent->flags) & KERNFS_REMOVED)

		goto out;

	if (!kernfs_get_active(kn))

		goto out_put_new_parent;



	mutex_lock(&kernfs_mutex);



	error = 0;

	if ((kn->parent == new_parent) && (kn->ns == new_ns) &&

	    (strcmp(kn->name, new_name) == 0))

		goto out_unlock;	/* nothing to rename */

		goto out;	/* nothing to rename */



	error = -EEXIST;

	if (kernfs_find_ns(new_parent, new_name, new_ns))

		goto out_unlock;

		goto out;



	/* rename kernfs_node */

	if (strcmp(kn->name, new_name) != 0) {

		error = -ENOMEM;

		new_name = kstrdup(new_name, GFP_KERNEL);

		if (!new_name)

			goto out_unlock;

			goto out;



		if (kn->flags & KERNFS_STATIC_NAME)

			kn->flags &= ~KERNFS_STATIC_NAME;
@@ -947,12 +941,8 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, 
	kernfs_link_sibling(kn);



	error = 0;

out_unlock:

	mutex_unlock(&kernfs_mutex);

	kernfs_put_active(kn);

out_put_new_parent:

	kernfs_put_active(new_parent);

 out:

	mutex_unlock(&kernfs_mutex);

	return error;

}
@@ -972,7 +962,8 @@ static struct kernfs_node *kernfs_dir_pos(const void *ns, 
	struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos)

{

	if (pos) {

		int valid = pos->parent == parent && hash == pos->hash;

		int valid = !(pos->flags & KERNFS_REMOVED) &&

			pos->parent == parent && hash == pos->hash;

		kernfs_put(pos);

		if (!valid)

			pos = NULL;

fs/kernfs/file.c

+3 −7
Original line number Diff line number Diff line
@@ -856,13 +856,9 @@ 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);

	}



	if (rc) {

		kernfs_put(kn);

fs/kernfs/kernfs-internal.h

+1 −2
Original line number Diff line number Diff line
@@ -26,8 +26,7 @@ struct kernfs_iattrs { 
	struct simple_xattrs	xattrs;

};



/* +1 to avoid triggering overflow warning when negating it */

#define KN_DEACTIVATED_BIAS		(INT_MIN + 1)

#define KN_DEACTIVATED_BIAS		INT_MIN



/* KERNFS_TYPE_MASK and types are defined in include/linux/kernfs.h */

fs/kernfs/symlink.c

+3 −7
Original line number Diff line number Diff line
@@ -40,13 +40,9 @@ 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);

	}



	if (!error)

		return kn;

include/linux/kernfs.h

+1 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ enum kernfs_node_type { 
#define KERNFS_FLAG_MASK	~KERNFS_TYPE_MASK



enum kernfs_node_flag {

	KERNFS_REMOVED		= 0x0010,

	KERNFS_NS		= 0x0020,

	KERNFS_HAS_SEQ_SHOW	= 0x0040,

	KERNFS_HAS_MMAP		= 0x0080,