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![FUJITA Tomonori](/assets/img/avatar_default.png)
cmd_filter works only for the block layer SG_IO with SCSI block devices. It breaks scsi/sg.c, bsg, and the block layer SG_IO with SCSI character devices (such as st). We hit a kernel crash with them. The problem is that cmd_filter code accesses to gendisk (having struct blk_scsi_cmd_filter) via inode->i_bdev->bd_disk. It works for only SCSI block device files. With character device files, inode->i_bdev leads you to struct cdev. inode->i_bdev->bd_disk->blk_scsi_cmd_filter isn't safe. SCSI ULDs don't expose gendisk; they keep it private. bsg needs to be independent on any protocols. We shouldn't change ULDs to expose their gendisk. This patch moves struct blk_scsi_cmd_filter from gendisk to request_queue, a common object, which eveyone can access to. The user interface doesn't change; users can change the filters via /sys/block/. gendisk has a pointer to request_queue so the cmd_filter code accesses to struct blk_scsi_cmd_filter. Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
229 lines
5.4 KiB
C
229 lines
5.4 KiB
C
/*
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* Copyright 2004 Peter M. Jones <pjones@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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*
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public Licens
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
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*
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*/
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#include <linux/list.h>
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#include <linux/genhd.h>
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#include <linux/spinlock.h>
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#include <linux/parser.h>
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#include <linux/capability.h>
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#include <linux/bitops.h>
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#include <scsi/scsi.h>
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#include <linux/cdrom.h>
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int blk_verify_command(struct blk_scsi_cmd_filter *filter,
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unsigned char *cmd, int has_write_perm)
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{
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/* root can do any command. */
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if (capable(CAP_SYS_RAWIO))
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return 0;
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/* if there's no filter set, assume we're filtering everything out */
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if (!filter)
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return -EPERM;
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/* Anybody who can open the device can do a read-safe command */
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if (test_bit(cmd[0], filter->read_ok))
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return 0;
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/* Write-safe commands require a writable open */
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if (test_bit(cmd[0], filter->write_ok) && has_write_perm)
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return 0;
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return -EPERM;
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}
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EXPORT_SYMBOL(blk_verify_command);
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/* and now, the sysfs stuff */
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static ssize_t rcf_cmds_show(struct blk_scsi_cmd_filter *filter, char *page,
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int rw)
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{
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char *npage = page;
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unsigned long *okbits;
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int i;
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if (rw == READ)
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okbits = filter->read_ok;
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else
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okbits = filter->write_ok;
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for (i = 0; i < BLK_SCSI_MAX_CMDS; i++) {
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if (test_bit(i, okbits)) {
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sprintf(npage, "%02x", i);
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npage += 2;
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if (i < BLK_SCSI_MAX_CMDS - 1)
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sprintf(npage++, " ");
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}
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}
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if (npage != page)
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npage += sprintf(npage, "\n");
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return npage - page;
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}
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static ssize_t rcf_readcmds_show(struct blk_scsi_cmd_filter *filter, char *page)
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{
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return rcf_cmds_show(filter, page, READ);
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}
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static ssize_t rcf_writecmds_show(struct blk_scsi_cmd_filter *filter,
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char *page)
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{
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return rcf_cmds_show(filter, page, WRITE);
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}
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static ssize_t rcf_cmds_store(struct blk_scsi_cmd_filter *filter,
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const char *page, size_t count, int rw)
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{
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ssize_t ret = 0;
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unsigned long okbits[BLK_SCSI_CMD_PER_LONG], *target_okbits;
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int cmd, status, len;
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substring_t ss;
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memset(&okbits, 0, sizeof(okbits));
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for (len = strlen(page); len > 0; len -= 3) {
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if (len < 2)
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break;
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ss.from = (char *) page + ret;
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ss.to = (char *) page + ret + 2;
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ret += 3;
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status = match_hex(&ss, &cmd);
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/* either of these cases means invalid input, so do nothing. */
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if (status || cmd >= BLK_SCSI_MAX_CMDS)
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return -EINVAL;
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__set_bit(cmd, okbits);
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}
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if (rw == READ)
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target_okbits = filter->read_ok;
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else
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target_okbits = filter->write_ok;
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memmove(target_okbits, okbits, sizeof(okbits));
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return count;
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}
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static ssize_t rcf_readcmds_store(struct blk_scsi_cmd_filter *filter,
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const char *page, size_t count)
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{
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return rcf_cmds_store(filter, page, count, READ);
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}
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static ssize_t rcf_writecmds_store(struct blk_scsi_cmd_filter *filter,
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const char *page, size_t count)
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{
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return rcf_cmds_store(filter, page, count, WRITE);
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}
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struct rcf_sysfs_entry {
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struct attribute attr;
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ssize_t (*show)(struct blk_scsi_cmd_filter *, char *);
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ssize_t (*store)(struct blk_scsi_cmd_filter *, const char *, size_t);
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};
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static struct rcf_sysfs_entry rcf_readcmds_entry = {
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.attr = { .name = "read_table", .mode = S_IRUGO | S_IWUSR },
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.show = rcf_readcmds_show,
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.store = rcf_readcmds_store,
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};
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static struct rcf_sysfs_entry rcf_writecmds_entry = {
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.attr = {.name = "write_table", .mode = S_IRUGO | S_IWUSR },
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.show = rcf_writecmds_show,
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.store = rcf_writecmds_store,
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};
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static struct attribute *default_attrs[] = {
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&rcf_readcmds_entry.attr,
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&rcf_writecmds_entry.attr,
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NULL,
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};
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#define to_rcf(atr) container_of((atr), struct rcf_sysfs_entry, attr)
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static ssize_t
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rcf_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
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{
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struct rcf_sysfs_entry *entry = to_rcf(attr);
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struct blk_scsi_cmd_filter *filter;
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filter = container_of(kobj, struct blk_scsi_cmd_filter, kobj);
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if (entry->show)
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return entry->show(filter, page);
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return 0;
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}
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static ssize_t
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rcf_attr_store(struct kobject *kobj, struct attribute *attr,
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const char *page, size_t length)
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{
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struct rcf_sysfs_entry *entry = to_rcf(attr);
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struct blk_scsi_cmd_filter *filter;
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if (!capable(CAP_SYS_RAWIO))
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return -EPERM;
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if (!entry->store)
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return -EINVAL;
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filter = container_of(kobj, struct blk_scsi_cmd_filter, kobj);
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return entry->store(filter, page, length);
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}
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static struct sysfs_ops rcf_sysfs_ops = {
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.show = rcf_attr_show,
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.store = rcf_attr_store,
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};
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static struct kobj_type rcf_ktype = {
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.sysfs_ops = &rcf_sysfs_ops,
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.default_attrs = default_attrs,
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};
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int blk_register_filter(struct gendisk *disk)
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{
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int ret;
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struct blk_scsi_cmd_filter *filter = &disk->queue->cmd_filter;
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struct kobject *parent = kobject_get(disk->holder_dir->parent);
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if (!parent)
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return -ENODEV;
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ret = kobject_init_and_add(&filter->kobj, &rcf_ktype, parent,
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"%s", "cmd_filter");
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if (ret < 0)
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return ret;
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return 0;
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}
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void blk_unregister_filter(struct gendisk *disk)
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{
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struct blk_scsi_cmd_filter *filter = &disk->queue->cmd_filter;
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kobject_put(&filter->kobj);
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kobject_put(disk->holder_dir->parent);
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}
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