fs/ocfs2/mmap.c

   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
  47 static vm_fault_t ocfs2_fault(struct vm_fault *vmf)
  48 {
  49         struct vm_area_struct *vma = vmf->vma;
  50         sigset_t oldset;
  51         vm_fault_t ret;
  52
  53         ocfs2_block_signals(&oldset);
  54         ret = filemap_fault(vmf);
  55         ocfs2_unblock_signals(&oldset);
  56
  57         trace_ocfs2_fault(OCFS2_I(vma->vm_file->f_mapping->host)->ip_blkno,
  58                           vma, vmf->page, vmf->pgoff);
  59         return ret;
  60 }
  61
  62 static vm_fault_t __ocfs2_page_mkwrite(struct file *file,
  63                         struct buffer_head *di_bh, struct page *page)
  64 {
  65         int err;
  66         vm_fault_t ret = VM_FAULT_NOPAGE;
  67         struct inode *inode = file_inode(file);
  68         struct address_space *mapping = inode->i_mapping;
  69         loff_t pos = page_offset(page);
  70         unsigned int len = PAGE_SIZE;
  71         pgoff_t last_index;
  72         struct page *locked_page = NULL;
  73         void *fsdata;
  74         loff_t size = i_size_read(inode);
  75
  76         last_index = (size - 1) >> PAGE_SHIFT;
  77
  78         /*
  79          * There are cases that lead to the page no longer bebongs to the
  80          * mapping.
  81          * 1) pagecache truncates locally due to memory pressure.
  82          * 2) pagecache truncates when another is taking EX lock against
  83          * inode lock. see ocfs2_data_convert_worker.
  84          *
  85          * The i_size check doesn't catch the case where nodes truncated and
  86          * then re-extended the file. We'll re-check the page mapping after
  87          * taking the page lock inside of ocfs2_write_begin_nolock().
  88          *
  89          * Let VM retry with these cases.
  90          */
  91         if ((page->mapping != inode->i_mapping) ||
  92             (!PageUptodate(page)) ||
  93             (page_offset(page) >= size))
  94                 goto out;
  95
  96         /*
  97          * Call ocfs2_write_begin() and ocfs2_write_end() to take
  98          * advantage of the allocation code there. We pass a write
  99          * length of the whole page (chopped to i_size) to make sure
 100          * the whole thing is allocated.
 101          *
 102          * Since we know the page is up to date, we don't have to
 103          * worry about ocfs2_write_begin() skipping some buffer reads
 104          * because the "write" would invalidate their data.
 105          */
 106         if (page->index == last_index)
 107                 len = ((size - 1) & ~PAGE_MASK) + 1;
 108
 109         err = ocfs2_write_begin_nolock(mapping, pos, len, OCFS2_WRITE_MMAP,
 110                                        &locked_page, &fsdata, di_bh, page);
 111         if (err) {
 112                 if (err != -ENOSPC)
 113                         mlog_errno(err);
 114                 ret = vmf_error(err);
 115                 goto out;
 116         }
 117
 118         if (!locked_page) {
 119                 ret = VM_FAULT_NOPAGE;
 120                 goto out;
 121         }
 122         err = ocfs2_write_end_nolock(mapping, pos, len, len, fsdata);
 123         BUG_ON(err != len);
 124         ret = VM_FAULT_LOCKED;
 125 out:
 126         return ret;
 127 }
 128
 129 static vm_fault_t ocfs2_page_mkwrite(struct vm_fault *vmf)
 130 {
 131         struct page *page = vmf->page;
 132         struct inode *inode = file_inode(vmf->vma->vm_file);
 133         struct buffer_head *di_bh = NULL;
 134         sigset_t oldset;
 135         int err;
 136         vm_fault_t ret;
 137
 138         sb_start_pagefault(inode->i_sb);
 139         ocfs2_block_signals(&oldset);
 140
 141         /*
 142          * The cluster locks taken will block a truncate from another
 143          * node. Taking the data lock will also ensure that we don't
 144          * attempt page truncation as part of a downconvert.
 145          */
 146         err = ocfs2_inode_lock(inode, &di_bh, 1);
 147         if (err < 0) {
 148                 mlog_errno(err);
 149                 ret = vmf_error(err);
 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(vmf->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
 167 out:
 168         ocfs2_unblock_signals(&oldset);
 169         sb_end_pagefault(inode->i_sb);
 170         return ret;
 171 }
 172
 173 static const struct vm_operations_struct ocfs2_file_vm_ops = {
 174         .fault          = ocfs2_fault,
 175         .page_mkwrite   = ocfs2_page_mkwrite,
 176 };
 177
 178 int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
 179 {
 180         int ret = 0, lock_level = 0;
 181
 182         ret = ocfs2_inode_lock_atime(file_inode(file),
 183                                     file->f_path.mnt, &lock_level, 1);
 184         if (ret < 0) {
 185                 mlog_errno(ret);
 186                 goto out;
 187         }
 188         ocfs2_inode_unlock(file_inode(file), lock_level);
 189 out:
 190         vma->vm_ops = &ocfs2_file_vm_ops;
 191         return 0;
 192 }
 193