linux/fs/ocfs2/ocfs2_lockid.h
wengang wang 6ca497a83e ocfs2: fix rare stale inode errors when exporting via nfs
For nfs exporting, ocfs2_get_dentry() returns the dentry for fh.
ocfs2_get_dentry() may read from disk when the inode is not in memory,
without any cross cluster lock. this leads to the file system loading a
stale inode.

This patch fixes above problem.

Solution is that in case of inode is not in memory, we get the cluster
lock(PR) of alloc inode where the inode in question is allocated from (this
causes node on which deletion is done sync the alloc inode) before reading
out the inode itsself. then we check the bitmap in the group (the inode in
question allcated from) to see if the bit is clear. if it's clear then it's
stale. if the bit is set, we then check generation as the existing code
does.

We have to read out the inode in question from disk first to know its alloc
slot and allot bit. And if its not stale we read it out using ocfs2_iget().
The second read should then be from cache.

And also we have to add a per superblock nfs_sync_lock to cover the lock for
alloc inode and that for inode in question. this is because ocfs2_get_dentry()
and ocfs2_delete_inode() lock on them in reverse order. nfs_sync_lock is locked
in EX mode in ocfs2_get_dentry() and in PR mode in ocfs2_delete_inode(). so
that mutliple ocfs2_delete_inode() can run concurrently in normal case.

[mfasheh@suse.com: build warning fixes and comment cleanups]
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Acked-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
2009-04-03 11:39:25 -07:00

118 lines
2.9 KiB
C

/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* ocfs2_lockid.h
*
* Defines OCFS2 lockid bits.
*
* Copyright (C) 2002, 2005 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.
*/
#ifndef OCFS2_LOCKID_H
#define OCFS2_LOCKID_H
/* lock ids are made up in the following manner:
* name[0] --> type
* name[1-6] --> 6 pad characters, reserved for now
* name[7-22] --> block number, expressed in hex as 16 chars
* name[23-30] --> i_generation, expressed in hex 8 chars
* name[31] --> '\0' */
#define OCFS2_LOCK_ID_MAX_LEN 32
#define OCFS2_LOCK_ID_PAD "000000"
#define OCFS2_DENTRY_LOCK_INO_START 18
enum ocfs2_lock_type {
OCFS2_LOCK_TYPE_META = 0,
OCFS2_LOCK_TYPE_DATA,
OCFS2_LOCK_TYPE_SUPER,
OCFS2_LOCK_TYPE_RENAME,
OCFS2_LOCK_TYPE_RW,
OCFS2_LOCK_TYPE_DENTRY,
OCFS2_LOCK_TYPE_OPEN,
OCFS2_LOCK_TYPE_FLOCK,
OCFS2_LOCK_TYPE_QINFO,
OCFS2_LOCK_TYPE_NFS_SYNC,
OCFS2_NUM_LOCK_TYPES
};
static inline char ocfs2_lock_type_char(enum ocfs2_lock_type type)
{
char c;
switch (type) {
case OCFS2_LOCK_TYPE_META:
c = 'M';
break;
case OCFS2_LOCK_TYPE_DATA:
c = 'D';
break;
case OCFS2_LOCK_TYPE_SUPER:
c = 'S';
break;
case OCFS2_LOCK_TYPE_RENAME:
c = 'R';
break;
case OCFS2_LOCK_TYPE_RW:
c = 'W';
break;
case OCFS2_LOCK_TYPE_DENTRY:
c = 'N';
break;
case OCFS2_LOCK_TYPE_OPEN:
c = 'O';
break;
case OCFS2_LOCK_TYPE_FLOCK:
c = 'F';
break;
case OCFS2_LOCK_TYPE_QINFO:
c = 'Q';
break;
case OCFS2_LOCK_TYPE_NFS_SYNC:
c = 'Y';
break;
default:
c = '\0';
}
return c;
}
static char *ocfs2_lock_type_strings[] = {
[OCFS2_LOCK_TYPE_META] = "Meta",
[OCFS2_LOCK_TYPE_DATA] = "Data",
[OCFS2_LOCK_TYPE_SUPER] = "Super",
[OCFS2_LOCK_TYPE_RENAME] = "Rename",
/* Need to differntiate from [R]ename.. serializing writes is the
* important job it does, anyway. */
[OCFS2_LOCK_TYPE_RW] = "Write/Read",
[OCFS2_LOCK_TYPE_DENTRY] = "Dentry",
[OCFS2_LOCK_TYPE_OPEN] = "Open",
[OCFS2_LOCK_TYPE_FLOCK] = "Flock",
[OCFS2_LOCK_TYPE_QINFO] = "Quota",
};
static inline const char *ocfs2_lock_type_string(enum ocfs2_lock_type type)
{
#ifdef __KERNEL__
BUG_ON(type >= OCFS2_NUM_LOCK_TYPES);
#endif
return ocfs2_lock_type_strings[type];
}
#endif /* OCFS2_LOCKID_H */