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 int ocfs2_fault(struct vm_fault *vmf)
  48 {
  49         struct vm_area_struct *vma = vmf->vma;
  50         sigset_t oldset;
  51         int 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 int __ocfs2_page_mkwrite(struct file *file, struct buffer_head *di_bh,
  63                                 struct page *page)
  64 {
  65         int ret = VM_FAULT_NOPAGE;
  66         struct inode *inode = file_inode(file);
  67         struct address_space *mapping = inode->i_mapping;
  68         loff_t pos = page_offset(page);
  69         unsigned int len = PAGE_SIZE;
  70         pgoff_t last_index;
  71         struct page *locked_page = NULL;
  72         void *fsdata;
  73         loff_t size = i_size_read(inode);
  74
  75         last_index = (size - 1) >> PAGE_SHIFT;
  76
  77         /*
  78          * There are cases that lead to the page no longer bebongs to the
  79          * mapping.
  80          * 1) pagecache truncates locally due to memory pressure.
  81          * 2) pagecache truncates when another is taking EX lock against
  82          * inode lock. see ocfs2_data_convert_worker.
  83          *
  84          * The i_size check doesn't catch the case where nodes truncated and
  85          * then re-extended the file. We'll re-check the page mapping after
  86          * taking the page lock inside of ocfs2_write_begin_nolock().
  87          *
  88          * Let VM retry with these cases.
  89          */
  90         if ((page->mapping != inode->i_mapping) ||
  91             (!PageUptodate(page)) ||
  92             (page_offset(page) >= size))
  93                 goto out;
  94
  95         /*
  96          * Call ocfs2_write_begin() and ocfs2_write_end() to take
  97          * advantage of the allocation code there. We pass a write
  98          * length of the whole page (chopped to i_size) to make sure
  99          * the whole thing is allocated.
 100          *
 101          * Since we know the page is up to date, we don't have to
 102          * worry about ocfs2_write_begin() skipping some buffer reads
 103          * because the "write" would invalidate their data.
 104          */
 105         if (page->index == last_index)
 106                 len = ((size - 1) & ~PAGE_MASK) + 1;
 107
 108         ret = ocfs2_write_begin_nolock(mapping, pos, len, OCFS2_WRITE_MMAP,
 109                                        &locked_page, &fsdata, di_bh, page);
 110         if (ret) {
 111                 if (ret != -ENOSPC)
 112                         mlog_errno(ret);
 113                 if (ret == -ENOMEM)
 114                         ret = VM_FAULT_OOM;
 115                 else
 116                         ret = VM_FAULT_SIGBUS;
 117                 goto out;
 118         }
 119
 120         if (!locked_page) {
 121                 ret = VM_FAULT_NOPAGE;
 122                 goto out;
 123         }
 124         ret = ocfs2_write_end_nolock(mapping, pos, len, len, fsdata);
 125         BUG_ON(ret != len);
 126         ret = VM_FAULT_LOCKED;
 127 out:
 128         return ret;
 129 }
 130
 131 static int ocfs2_page_mkwrite(struct vm_fault *vmf)
 132 {
 133         struct page *page = vmf->page;
 134         struct inode *inode = file_inode(vmf->vma->vm_file);
 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                 if (ret == -ENOMEM)
 151                         ret = VM_FAULT_OOM;
 152                 else
 153                         ret = VM_FAULT_SIGBUS;
 154                 goto out;
 155         }
 156
 157         /*
 158          * The alloc sem should be enough to serialize with
 159          * ocfs2_truncate_file() changing i_size as well as any thread
 160          * modifying the inode btree.
 161          */
 162         down_write(&OCFS2_I(inode)->ip_alloc_sem);
 163
 164         ret = __ocfs2_page_mkwrite(vmf->vma->vm_file, di_bh, page);
 165
 166         up_write(&OCFS2_I(inode)->ip_alloc_sem);
 167
 168         brelse(di_bh);
 169         ocfs2_inode_unlock(inode, 1);
 170
 171 out:
 172         ocfs2_unblock_signals(&oldset);
 173         sb_end_pagefault(inode->i_sb);
 174         return ret;
 175 }
 176
 177 static const struct vm_operations_struct ocfs2_file_vm_ops = {
 178         .fault          = ocfs2_fault,
 179         .page_mkwrite   = ocfs2_page_mkwrite,
 180 };
 181
 182 int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
 183 {
 184         int ret = 0, lock_level = 0;
 185
 186         ret = ocfs2_inode_lock_atime(file_inode(file),
 187                                     file->f_path.mnt, &lock_level);
 188         if (ret < 0) {
 189                 mlog_errno(ret);
 190                 goto out;
 191         }
 192         ocfs2_inode_unlock(file_inode(file), lock_level);
 193 out:
 194         vma->vm_ops = &ocfs2_file_vm_ops;
 195         return 0;
 196 }
 197