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 #define MLOG_MASK_PREFIX ML_FILE_IO
  35 #include <cluster/masklog.h>
  36
  37 #include "ocfs2.h"
  38
  39 #include "aops.h"
  40 #include "dlmglue.h"
  41 #include "file.h"
  42 #include "inode.h"
  43 #include "mmap.h"
  44 #include "super.h"
  45
  46
  47 static int ocfs2_fault(struct vm_area_struct *area, struct vm_fault *vmf)
  48 {
  49         sigset_t oldset;
  50         int ret;
  51
  52         mlog_entry("(area=%p, page offset=%lu)\n", area, vmf->pgoff);
  53
  54         ocfs2_block_signals(&oldset);
  55         ret = filemap_fault(area, vmf);
  56         ocfs2_unblock_signals(&oldset);
  57
  58         mlog_exit_ptr(vmf->page);
  59         return ret;
  60 }
  61
  62 static int __ocfs2_page_mkwrite(struct inode *inode, struct buffer_head *di_bh,
  63                                 struct page *page)
  64 {
  65         int ret;
  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         /*
  75          * Another node might have truncated while we were waiting on
  76          * cluster locks.
  77          * We don't check size == 0 before the shift. This is borrowed
  78          * from do_generic_file_read.
  79          */
  80         last_index = (size - 1) >> PAGE_CACHE_SHIFT;
  81         if (unlikely(!size || page->index > last_index)) {
  82                 ret = -EINVAL;
  83                 goto out;
  84         }
  85
  86         /*
  87          * The i_size check above doesn't catch the case where nodes
  88          * truncated and then re-extended the file. We'll re-check the
  89          * page mapping after taking the page lock inside of
  90          * ocfs2_write_begin_nolock().
  91          */
  92         if (!PageUptodate(page) || page->mapping != inode->i_mapping) {
  93                 /*
  94                  * the page has been umapped in ocfs2_data_downconvert_worker.
  95                  * So return 0 here and let VFS retry.
  96                  */
  97                 ret = 0;
  98                 goto out;
  99         }
 100
 101         /*
 102          * Call ocfs2_write_begin() and ocfs2_write_end() to take
 103          * advantage of the allocation code there. We pass a write
 104          * length of the whole page (chopped to i_size) to make sure
 105          * the whole thing is allocated.
 106          *
 107          * Since we know the page is up to date, we don't have to
 108          * worry about ocfs2_write_begin() skipping some buffer reads
 109          * because the "write" would invalidate their data.
 110          */
 111         if (page->index == last_index)
 112                 len = ((size - 1) & ~PAGE_CACHE_MASK) + 1;
 113
 114         ret = ocfs2_write_begin_nolock(mapping, pos, len, 0, &locked_page,
 115                                        &fsdata, di_bh, page);
 116         if (ret) {
 117                 if (ret != -ENOSPC)
 118                         mlog_errno(ret);
 119                 goto out;
 120         }
 121
 122         ret = ocfs2_write_end_nolock(mapping, pos, len, len, locked_page,
 123                                      fsdata);
 124         if (ret < 0) {
 125                 mlog_errno(ret);
 126                 goto out;
 127         }
 128         BUG_ON(ret != len);
 129         ret = 0;
 130 out:
 131         return ret;
 132 }
 133
 134 static int ocfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 135 {
 136         struct page *page = vmf->page;
 137         struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
 138         struct buffer_head *di_bh = NULL;
 139         sigset_t oldset;
 140         int ret;
 141
 142         ocfs2_block_signals(&oldset);
 143
 144         /*
 145          * The cluster locks taken will block a truncate from another
 146          * node. Taking the data lock will also ensure that we don't
 147          * attempt page truncation as part of a downconvert.
 148          */
 149         ret = ocfs2_inode_lock(inode, &di_bh, 1);
 150         if (ret < 0) {
 151                 mlog_errno(ret);
 152                 goto out;
 153         }
 154
 155         /*
 156          * The alloc sem should be enough to serialize with
 157          * ocfs2_truncate_file() changing i_size as well as any thread
 158          * modifying the inode btree.
 159          */
 160         down_write(&OCFS2_I(inode)->ip_alloc_sem);
 161
 162         ret = __ocfs2_page_mkwrite(inode, di_bh, page);
 163
 164         up_write(&OCFS2_I(inode)->ip_alloc_sem);
 165
 166         brelse(di_bh);
 167         ocfs2_inode_unlock(inode, 1);
 168
 169 out:
 170         ocfs2_unblock_signals(&oldset);
 171         if (ret)
 172                 ret = VM_FAULT_SIGBUS;
 173         return ret;
 174 }
 175
 176 static const struct vm_operations_struct ocfs2_file_vm_ops = {
 177         .fault          = ocfs2_fault,
 178         .page_mkwrite   = ocfs2_page_mkwrite,
 179 };
 180
 181 int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
 182 {
 183         int ret = 0, lock_level = 0;
 184
 185         ret = ocfs2_inode_lock_atime(file->f_dentry->d_inode,
 186                                     file->f_vfsmnt, &lock_level);
 187         if (ret < 0) {
 188                 mlog_errno(ret);
 189                 goto out;
 190         }
 191         ocfs2_inode_unlock(file->f_dentry->d_inode, lock_level);
 192 out:
 193         vma->vm_ops = &ocfs2_file_vm_ops;
 194         vma->vm_flags |= VM_CAN_NONLINEAR;
 195         return 0;
 196 }
 197