linux-stable/fs/ocfs2/sysfile.c
jiangyiwen 43b10a2037 ocfs2: avoid system inode ref confusion by adding mutex lock
The following case may lead to the same system inode ref in confusion.

A thread                            B thread
ocfs2_get_system_file_inode
->get_local_system_inode
->_ocfs2_get_system_file_inode
                                    because of *arr == NULL,
                                    ocfs2_get_system_file_inode
                                    ->get_local_system_inode
                                    ->_ocfs2_get_system_file_inode
gets first ref thru
_ocfs2_get_system_file_inode,
gets second ref thru igrab and
set *arr = inode
                                    at the moment, B thread also gets
                                    two refs, so lead to one more
                                    inode ref.

So add mutex lock to avoid multi thread set two inode ref once at the
same time.

Signed-off-by: jiangyiwen <jiangyiwen@huawei.com>
Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-03 16:20:57 -07:00

182 lines
4.7 KiB
C

/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* sysfile.c
*
* Initialize, read, write, etc. system files.
*
* Copyright (C) 2002, 2004 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/highmem.h>
#include <cluster/masklog.h>
#include "ocfs2.h"
#include "alloc.h"
#include "dir.h"
#include "inode.h"
#include "journal.h"
#include "sysfile.h"
#include "buffer_head_io.h"
static struct inode * _ocfs2_get_system_file_inode(struct ocfs2_super *osb,
int type,
u32 slot);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
static struct lock_class_key ocfs2_sysfile_cluster_lock_key[NUM_SYSTEM_INODES];
#endif
static inline int is_global_system_inode(int type)
{
return type >= OCFS2_FIRST_ONLINE_SYSTEM_INODE &&
type <= OCFS2_LAST_GLOBAL_SYSTEM_INODE;
}
static struct inode **get_local_system_inode(struct ocfs2_super *osb,
int type,
u32 slot)
{
int index;
struct inode **local_system_inodes, **free = NULL;
BUG_ON(slot == OCFS2_INVALID_SLOT);
BUG_ON(type < OCFS2_FIRST_LOCAL_SYSTEM_INODE ||
type > OCFS2_LAST_LOCAL_SYSTEM_INODE);
spin_lock(&osb->osb_lock);
local_system_inodes = osb->local_system_inodes;
spin_unlock(&osb->osb_lock);
if (unlikely(!local_system_inodes)) {
local_system_inodes = kzalloc(sizeof(struct inode *) *
NUM_LOCAL_SYSTEM_INODES *
osb->max_slots,
GFP_NOFS);
if (!local_system_inodes) {
mlog_errno(-ENOMEM);
/*
* return NULL here so that ocfs2_get_sytem_file_inodes
* will try to create an inode and use it. We will try
* to initialize local_system_inodes next time.
*/
return NULL;
}
spin_lock(&osb->osb_lock);
if (osb->local_system_inodes) {
/* Someone has initialized it for us. */
free = local_system_inodes;
local_system_inodes = osb->local_system_inodes;
} else
osb->local_system_inodes = local_system_inodes;
spin_unlock(&osb->osb_lock);
kfree(free);
}
index = (slot * NUM_LOCAL_SYSTEM_INODES) +
(type - OCFS2_FIRST_LOCAL_SYSTEM_INODE);
return &local_system_inodes[index];
}
struct inode *ocfs2_get_system_file_inode(struct ocfs2_super *osb,
int type,
u32 slot)
{
struct inode *inode = NULL;
struct inode **arr = NULL;
/* avoid the lookup if cached in local system file array */
if (is_global_system_inode(type)) {
arr = &(osb->global_system_inodes[type]);
} else
arr = get_local_system_inode(osb, type, slot);
mutex_lock(&osb->system_file_mutex);
if (arr && ((inode = *arr) != NULL)) {
/* get a ref in addition to the array ref */
inode = igrab(inode);
mutex_unlock(&osb->system_file_mutex);
BUG_ON(!inode);
return inode;
}
/* this gets one ref thru iget */
inode = _ocfs2_get_system_file_inode(osb, type, slot);
/* add one more if putting into array for first time */
if (arr && inode) {
*arr = igrab(inode);
BUG_ON(!*arr);
}
mutex_unlock(&osb->system_file_mutex);
return inode;
}
static struct inode * _ocfs2_get_system_file_inode(struct ocfs2_super *osb,
int type,
u32 slot)
{
char namebuf[40];
struct inode *inode = NULL;
u64 blkno;
int status = 0;
ocfs2_sprintf_system_inode_name(namebuf,
sizeof(namebuf),
type, slot);
status = ocfs2_lookup_ino_from_name(osb->sys_root_inode, namebuf,
strlen(namebuf), &blkno);
if (status < 0) {
goto bail;
}
inode = ocfs2_iget(osb, blkno, OCFS2_FI_FLAG_SYSFILE, type);
if (IS_ERR(inode)) {
mlog_errno(PTR_ERR(inode));
inode = NULL;
goto bail;
}
#ifdef CONFIG_DEBUG_LOCK_ALLOC
if (type == LOCAL_USER_QUOTA_SYSTEM_INODE ||
type == LOCAL_GROUP_QUOTA_SYSTEM_INODE ||
type == JOURNAL_SYSTEM_INODE) {
/* Ignore inode lock on these inodes as the lock does not
* really belong to any process and lockdep cannot handle
* that */
OCFS2_I(inode)->ip_inode_lockres.l_lockdep_map.key = NULL;
} else {
lockdep_init_map(&OCFS2_I(inode)->ip_inode_lockres.
l_lockdep_map,
ocfs2_system_inodes[type].si_name,
&ocfs2_sysfile_cluster_lock_key[type], 0);
}
#endif
bail:
return inode;
}