Root/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
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;
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    /*
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(file, 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;
130out:
131    return ret;
132}
133
134static 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(vma->vm_file, 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
169out:
170    ocfs2_unblock_signals(&oldset);
171    if (ret)
172        ret = VM_FAULT_SIGBUS;
173    return ret;
174}
175
176static const struct vm_operations_struct ocfs2_file_vm_ops = {
177    .fault = ocfs2_fault,
178    .page_mkwrite = ocfs2_page_mkwrite,
179};
180
181int 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);
192out:
193    vma->vm_ops = &ocfs2_file_vm_ops;
194    vma->vm_flags |= VM_CAN_NONLINEAR;
195    return 0;
196}
197
198

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