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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 
47 static 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 
61 static 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;
127 out:
128  return ret;
129 }
130 
131 static 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 
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  .remap_pages = generic_file_remap_pages,
177 };
178 
179 int 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);
190 out:
191  vma->vm_ops = &ocfs2_file_vm_ops;
192  return 0;
193 }
194