linux/fs/ocfs2/sysfile.c
Mark Fasheh 24c19ef404 ocfs2: Remove i_generation from inode lock names
OCFS2 puts inode meta data in the "lock value block" provided by the DLM.
Typically, i_generation is encoded in the lock name so that a deleted inode
on and a new one in the same block don't share the same lvb.

Unfortunately, that scheme means that the read in ocfs2_read_locked_inode()
is potentially thrown away as soon as the meta data lock is taken - we
cannot encode the lock name without first knowing i_generation, which
requires a disk read.

This patch encodes i_generation in the inode meta data lvb, and removes the
value from the inode meta data lock name. This way, the read can be covered
by a lock, and at the same time we can distinguish between an up to date and
a stale LVB.

This will help cold-cache stat(2) performance in particular.

Since this patch changes the protocol version, we take the opportunity to do
a minor re-organization of two of the LVB fields.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
2006-09-24 13:50:46 -07:00

129 lines
3.2 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/slab.h>
#include <linux/highmem.h>
#define MLOG_MASK_PREFIX ML_INODE
#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);
static inline int is_global_system_inode(int type);
static inline int is_in_system_inode_array(struct ocfs2_super *osb,
int type,
u32 slot);
static inline int is_global_system_inode(int type)
{
return type >= OCFS2_FIRST_ONLINE_SYSTEM_INODE &&
type <= OCFS2_LAST_GLOBAL_SYSTEM_INODE;
}
static inline int is_in_system_inode_array(struct ocfs2_super *osb,
int type,
u32 slot)
{
return slot == osb->slot_num || is_global_system_inode(type);
}
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_in_system_inode_array(osb, type, slot))
arr = &(osb->system_inodes[type]);
if (arr && ((inode = *arr) != NULL)) {
/* get a ref in addition to the array ref */
inode = igrab(inode);
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);
}
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;
struct buffer_head *dirent_bh = NULL;
struct ocfs2_dir_entry *de = NULL;
int status = 0;
ocfs2_sprintf_system_inode_name(namebuf,
sizeof(namebuf),
type, slot);
status = ocfs2_find_files_on_disk(namebuf, strlen(namebuf),
&blkno, osb->sys_root_inode,
&dirent_bh, &de);
if (status < 0) {
goto bail;
}
inode = ocfs2_iget(osb, blkno, OCFS2_FI_FLAG_SYSFILE);
if (IS_ERR(inode)) {
mlog_errno(PTR_ERR(inode));
inode = NULL;
goto bail;
}
bail:
if (dirent_bh)
brelse(dirent_bh);
return inode;
}