mirror of
https://github.com/torvalds/linux.git
synced 2024-11-14 08:02:07 +00:00
2995fa78e4
This reverts commit be35f48610 ("dm: wait until embedded kobject is
released before destroying a device") and provides an improved fix.
The kobject release code that calls the completion must be placed in a
non-module file, otherwise there is a module unload race (if the process
calling dm_kobject_release is preempted and the DM module unloaded after
the completion is triggered, but before dm_kobject_release returns).
To fix this race, this patch moves the completion code to dm-builtin.c
which is always compiled directly into the kernel if BLK_DEV_DM is
selected.
The patch introduces a new dm_kobject_holder structure, its purpose is
to keep the completion and kobject in one place, so that it can be
accessed from non-module code without the need to export the layout of
struct mapped_device to that code.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
112 lines
2.3 KiB
C
112 lines
2.3 KiB
C
/*
|
|
* Copyright (C) 2008 Red Hat, Inc. All rights reserved.
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
|
|
#include <linux/sysfs.h>
|
|
#include <linux/dm-ioctl.h>
|
|
#include "dm.h"
|
|
|
|
struct dm_sysfs_attr {
|
|
struct attribute attr;
|
|
ssize_t (*show)(struct mapped_device *, char *);
|
|
ssize_t (*store)(struct mapped_device *, char *);
|
|
};
|
|
|
|
#define DM_ATTR_RO(_name) \
|
|
struct dm_sysfs_attr dm_attr_##_name = \
|
|
__ATTR(_name, S_IRUGO, dm_attr_##_name##_show, NULL)
|
|
|
|
static ssize_t dm_attr_show(struct kobject *kobj, struct attribute *attr,
|
|
char *page)
|
|
{
|
|
struct dm_sysfs_attr *dm_attr;
|
|
struct mapped_device *md;
|
|
ssize_t ret;
|
|
|
|
dm_attr = container_of(attr, struct dm_sysfs_attr, attr);
|
|
if (!dm_attr->show)
|
|
return -EIO;
|
|
|
|
md = dm_get_from_kobject(kobj);
|
|
if (!md)
|
|
return -EINVAL;
|
|
|
|
ret = dm_attr->show(md, page);
|
|
dm_put(md);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t dm_attr_name_show(struct mapped_device *md, char *buf)
|
|
{
|
|
if (dm_copy_name_and_uuid(md, buf, NULL))
|
|
return -EIO;
|
|
|
|
strcat(buf, "\n");
|
|
return strlen(buf);
|
|
}
|
|
|
|
static ssize_t dm_attr_uuid_show(struct mapped_device *md, char *buf)
|
|
{
|
|
if (dm_copy_name_and_uuid(md, NULL, buf))
|
|
return -EIO;
|
|
|
|
strcat(buf, "\n");
|
|
return strlen(buf);
|
|
}
|
|
|
|
static ssize_t dm_attr_suspended_show(struct mapped_device *md, char *buf)
|
|
{
|
|
sprintf(buf, "%d\n", dm_suspended_md(md));
|
|
|
|
return strlen(buf);
|
|
}
|
|
|
|
static DM_ATTR_RO(name);
|
|
static DM_ATTR_RO(uuid);
|
|
static DM_ATTR_RO(suspended);
|
|
|
|
static struct attribute *dm_attrs[] = {
|
|
&dm_attr_name.attr,
|
|
&dm_attr_uuid.attr,
|
|
&dm_attr_suspended.attr,
|
|
NULL,
|
|
};
|
|
|
|
static const struct sysfs_ops dm_sysfs_ops = {
|
|
.show = dm_attr_show,
|
|
};
|
|
|
|
/*
|
|
* dm kobject is embedded in mapped_device structure
|
|
* no need to define release function here
|
|
*/
|
|
static struct kobj_type dm_ktype = {
|
|
.sysfs_ops = &dm_sysfs_ops,
|
|
.default_attrs = dm_attrs,
|
|
.release = dm_kobject_release,
|
|
};
|
|
|
|
/*
|
|
* Initialize kobj
|
|
* because nobody using md yet, no need to call explicit dm_get/put
|
|
*/
|
|
int dm_sysfs_init(struct mapped_device *md)
|
|
{
|
|
return kobject_init_and_add(dm_kobject(md), &dm_ktype,
|
|
&disk_to_dev(dm_disk(md))->kobj,
|
|
"%s", "dm");
|
|
}
|
|
|
|
/*
|
|
* Remove kobj, called after all references removed
|
|
*/
|
|
void dm_sysfs_exit(struct mapped_device *md)
|
|
{
|
|
struct kobject *kobj = dm_kobject(md);
|
|
kobject_put(kobj);
|
|
wait_for_completion(dm_get_completion_from_kobject(kobj));
|
|
}
|