linux/fs/ocfs2/mmap.c
Tao Ma 4c1bbf1ba6 ocfs2: return 0 in page_mkwrite to let VFS retry.
In ocfs2_page_mkwrite, we return -EINVAL when we found the page mapping
isn't updated, and it will cause the user space program get SIGBUS and
exit. The reason is that during race writeable mmap, we will do
unmap_mapping_range in ocfs2_data_downconvert_worker. The good thing is
that if we reuturn 0 in page_mkwrite, VFS will retry fault and then
call page_mkwrite again, so it is safe to return 0 here.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
2008-11-10 09:51:47 -08:00

224 lines
5.5 KiB
C

/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* mmap.c
*
* Code to deal with the mess that is clustered mmap.
*
* 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>
#include <linux/pagemap.h>
#include <linux/uio.h>
#include <linux/signal.h>
#include <linux/rbtree.h>
#define MLOG_MASK_PREFIX ML_FILE_IO
#include <cluster/masklog.h>
#include "ocfs2.h"
#include "aops.h"
#include "dlmglue.h"
#include "file.h"
#include "inode.h"
#include "mmap.h"
static inline int ocfs2_vm_op_block_sigs(sigset_t *blocked, sigset_t *oldset)
{
/* The best way to deal with signals in the vm path is
* to block them upfront, rather than allowing the
* locking paths to return -ERESTARTSYS. */
sigfillset(blocked);
/* We should technically never get a bad return value
* from sigprocmask */
return sigprocmask(SIG_BLOCK, blocked, oldset);
}
static inline int ocfs2_vm_op_unblock_sigs(sigset_t *oldset)
{
return sigprocmask(SIG_SETMASK, oldset, NULL);
}
static int ocfs2_fault(struct vm_area_struct *area, struct vm_fault *vmf)
{
sigset_t blocked, oldset;
int error, ret;
mlog_entry("(area=%p, page offset=%lu)\n", area, vmf->pgoff);
error = ocfs2_vm_op_block_sigs(&blocked, &oldset);
if (error < 0) {
mlog_errno(error);
ret = VM_FAULT_SIGBUS;
goto out;
}
ret = filemap_fault(area, vmf);
error = ocfs2_vm_op_unblock_sigs(&oldset);
if (error < 0)
mlog_errno(error);
out:
mlog_exit_ptr(vmf->page);
return ret;
}
static int __ocfs2_page_mkwrite(struct inode *inode, struct buffer_head *di_bh,
struct page *page)
{
int ret;
struct address_space *mapping = inode->i_mapping;
loff_t pos = page_offset(page);
unsigned int len = PAGE_CACHE_SIZE;
pgoff_t last_index;
struct page *locked_page = NULL;
void *fsdata;
loff_t size = i_size_read(inode);
/*
* Another node might have truncated while we were waiting on
* cluster locks.
*/
last_index = size >> PAGE_CACHE_SHIFT;
if (page->index > last_index) {
ret = -EINVAL;
goto out;
}
/*
* The i_size check above doesn't catch the case where nodes
* truncated and then re-extended the file. We'll re-check the
* page mapping after taking the page lock inside of
* ocfs2_write_begin_nolock().
*/
if (!PageUptodate(page) || page->mapping != inode->i_mapping) {
/*
* the page has been umapped in ocfs2_data_downconvert_worker.
* So return 0 here and let VFS retry.
*/
ret = 0;
goto out;
}
/*
* Call ocfs2_write_begin() and ocfs2_write_end() to take
* advantage of the allocation code there. We pass a write
* length of the whole page (chopped to i_size) to make sure
* the whole thing is allocated.
*
* Since we know the page is up to date, we don't have to
* worry about ocfs2_write_begin() skipping some buffer reads
* because the "write" would invalidate their data.
*/
if (page->index == last_index)
len = size & ~PAGE_CACHE_MASK;
ret = ocfs2_write_begin_nolock(mapping, pos, len, 0, &locked_page,
&fsdata, di_bh, page);
if (ret) {
if (ret != -ENOSPC)
mlog_errno(ret);
goto out;
}
ret = ocfs2_write_end_nolock(mapping, pos, len, len, locked_page,
fsdata);
if (ret < 0) {
mlog_errno(ret);
goto out;
}
BUG_ON(ret != len);
ret = 0;
out:
return ret;
}
static int ocfs2_page_mkwrite(struct vm_area_struct *vma, struct page *page)
{
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
struct buffer_head *di_bh = NULL;
sigset_t blocked, oldset;
int ret, ret2;
ret = ocfs2_vm_op_block_sigs(&blocked, &oldset);
if (ret < 0) {
mlog_errno(ret);
return ret;
}
/*
* The cluster locks taken will block a truncate from another
* node. Taking the data lock will also ensure that we don't
* attempt page truncation as part of a downconvert.
*/
ret = ocfs2_inode_lock(inode, &di_bh, 1);
if (ret < 0) {
mlog_errno(ret);
goto out;
}
/*
* The alloc sem should be enough to serialize with
* ocfs2_truncate_file() changing i_size as well as any thread
* modifying the inode btree.
*/
down_write(&OCFS2_I(inode)->ip_alloc_sem);
ret = __ocfs2_page_mkwrite(inode, di_bh, page);
up_write(&OCFS2_I(inode)->ip_alloc_sem);
brelse(di_bh);
ocfs2_inode_unlock(inode, 1);
out:
ret2 = ocfs2_vm_op_unblock_sigs(&oldset);
if (ret2 < 0)
mlog_errno(ret2);
return ret;
}
static struct vm_operations_struct ocfs2_file_vm_ops = {
.fault = ocfs2_fault,
.page_mkwrite = ocfs2_page_mkwrite,
};
int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
{
int ret = 0, lock_level = 0;
ret = ocfs2_inode_lock_atime(file->f_dentry->d_inode,
file->f_vfsmnt, &lock_level);
if (ret < 0) {
mlog_errno(ret);
goto out;
}
ocfs2_inode_unlock(file->f_dentry->d_inode, lock_level);
out:
vma->vm_ops = &ocfs2_file_vm_ops;
vma->vm_flags |= VM_CAN_NONLINEAR;
return 0;
}