linux/fs/ocfs2/mmap.c
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   1/* -*- mode: c; c-basic-offset: 8; -*-
   2 * vim: noexpandtab sw=8 ts=8 sts=0:
   3 *
   4 * mmap.c
   5 *
   6 * Code to deal with the mess that is clustered mmap.
   7 *
   8 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
   9 *
  10 * This program is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU General Public
  12 * License as published by the Free Software Foundation; either
  13 * version 2 of the License, or (at your option) any later version.
  14 *
  15 * This program is distributed in the hope that it will be useful,
  16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18 * General Public License for more details.
  19 *
  20 * You should have received a copy of the GNU General Public
  21 * License along with this program; if not, write to the
  22 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 * Boston, MA 021110-1307, USA.
  24 */
  25
  26#include <linux/fs.h>
  27#include <linux/types.h>
  28#include <linux/highmem.h>
  29#include <linux/pagemap.h>
  30#include <linux/uio.h>
  31#include <linux/signal.h>
  32#include <linux/rbtree.h>
  33
  34#include <cluster/masklog.h>
  35
  36#include "ocfs2.h"
  37
  38#include "aops.h"
  39#include "dlmglue.h"
  40#include "file.h"
  41#include "inode.h"
  42#include "mmap.h"
  43#include "super.h"
  44#include "ocfs2_trace.h"
  45
  46
  47static int ocfs2_fault(struct vm_area_struct *area, struct vm_fault *vmf)
  48{
  49        sigset_t oldset;
  50        int ret;
  51
  52        ocfs2_block_signals(&oldset);
  53        ret = filemap_fault(area, vmf);
  54        ocfs2_unblock_signals(&oldset);
  55
  56        trace_ocfs2_fault(OCFS2_I(area->vm_file->f_mapping->host)->ip_blkno,
  57                          area, vmf->page, vmf->pgoff);
  58        return ret;
  59}
  60
  61static int __ocfs2_page_mkwrite(struct file *file, struct buffer_head *di_bh,
  62                                struct page *page)
  63{
  64        int ret = VM_FAULT_NOPAGE;
  65        struct inode *inode = file->f_path.dentry->d_inode;
  66        struct address_space *mapping = inode->i_mapping;
  67        loff_t pos = page_offset(page);
  68        unsigned int len = PAGE_CACHE_SIZE;
  69        pgoff_t last_index;
  70        struct page *locked_page = NULL;
  71        void *fsdata;
  72        loff_t size = i_size_read(inode);
  73
  74        last_index = (size - 1) >> PAGE_CACHE_SHIFT;
  75
  76        /*
  77         * There are cases that lead to the page no longer bebongs to the
  78         * mapping.
  79         * 1) pagecache truncates locally due to memory pressure.
  80         * 2) pagecache truncates when another is taking EX lock against 
  81         * inode lock. see ocfs2_data_convert_worker.
  82         * 
  83         * The i_size check doesn't catch the case where nodes truncated and
  84         * then re-extended the file. We'll re-check the page mapping after
  85         * taking the page lock inside of ocfs2_write_begin_nolock().
  86         *
  87         * Let VM retry with these cases.
  88         */
  89        if ((page->mapping != inode->i_mapping) ||
  90            (!PageUptodate(page)) ||
  91            (page_offset(page) >= size))
  92                goto out;
  93
  94        /*
  95         * Call ocfs2_write_begin() and ocfs2_write_end() to take
  96         * advantage of the allocation code there. We pass a write
  97         * length of the whole page (chopped to i_size) to make sure
  98         * the whole thing is allocated.
  99         *
 100         * Since we know the page is up to date, we don't have to
 101         * worry about ocfs2_write_begin() skipping some buffer reads
 102         * because the "write" would invalidate their data.
 103         */
 104        if (page->index == last_index)
 105                len = ((size - 1) & ~PAGE_CACHE_MASK) + 1;
 106
 107        ret = ocfs2_write_begin_nolock(file, mapping, pos, len, 0, &locked_page,
 108                                       &fsdata, di_bh, page);
 109        if (ret) {
 110                if (ret != -ENOSPC)
 111                        mlog_errno(ret);
 112                if (ret == -ENOMEM)
 113                        ret = VM_FAULT_OOM;
 114                else
 115                        ret = VM_FAULT_SIGBUS;
 116                goto out;
 117        }
 118
 119        if (!locked_page) {
 120                ret = VM_FAULT_NOPAGE;
 121                goto out;
 122        }
 123        ret = ocfs2_write_end_nolock(mapping, pos, len, len, locked_page,
 124                                     fsdata);
 125        BUG_ON(ret != len);
 126        ret = VM_FAULT_LOCKED;
 127out:
 128        return ret;
 129}
 130
 131static int ocfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 132{
 133        struct page *page = vmf->page;
 134        struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
 135        struct buffer_head *di_bh = NULL;
 136        sigset_t oldset;
 137        int ret;
 138
 139        sb_start_pagefault(inode->i_sb);
 140        ocfs2_block_signals(&oldset);
 141
 142        /*
 143         * The cluster locks taken will block a truncate from another
 144         * node. Taking the data lock will also ensure that we don't
 145         * attempt page truncation as part of a downconvert.
 146         */
 147        ret = ocfs2_inode_lock(inode, &di_bh, 1);
 148        if (ret < 0) {
 149                mlog_errno(ret);
 150                goto out;
 151        }
 152
 153        /*
 154         * The alloc sem should be enough to serialize with
 155         * ocfs2_truncate_file() changing i_size as well as any thread
 156         * modifying the inode btree.
 157         */
 158        down_write(&OCFS2_I(inode)->ip_alloc_sem);
 159
 160        ret = __ocfs2_page_mkwrite(vma->vm_file, di_bh, page);
 161
 162        up_write(&OCFS2_I(inode)->ip_alloc_sem);
 163
 164        brelse(di_bh);
 165        ocfs2_inode_unlock(inode, 1);
 166
 167out:
 168        ocfs2_unblock_signals(&oldset);
 169        sb_end_pagefault(inode->i_sb);
 170        return ret;
 171}
 172
 173static const struct vm_operations_struct ocfs2_file_vm_ops = {
 174        .fault          = ocfs2_fault,
 175        .page_mkwrite   = ocfs2_page_mkwrite,
 176        .remap_pages    = generic_file_remap_pages,
 177};
 178
 179int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
 180{
 181        int ret = 0, lock_level = 0;
 182
 183        ret = ocfs2_inode_lock_atime(file->f_dentry->d_inode,
 184                                    file->f_vfsmnt, &lock_level);
 185        if (ret < 0) {
 186                mlog_errno(ret);
 187                goto out;
 188        }
 189        ocfs2_inode_unlock(file->f_dentry->d_inode, lock_level);
 190out:
 191        vma->vm_ops = &ocfs2_file_vm_ops;
 192        return 0;
 193}
 194
 195
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