xref: /openbmc/linux/fs/ocfs2/mmap.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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/slab.h>
29 #include <linux/highmem.h>
30 #include <linux/pagemap.h>
31 #include <linux/uio.h>
32 #include <linux/signal.h>
33 #include <linux/rbtree.h>
34 
35 #define MLOG_MASK_PREFIX ML_FILE_IO
36 #include <cluster/masklog.h>
37 
38 #include "ocfs2.h"
39 
40 #include "dlmglue.h"
41 #include "file.h"
42 #include "inode.h"
43 #include "mmap.h"
44 
45 static struct page *ocfs2_nopage(struct vm_area_struct * area,
46 				 unsigned long address,
47 				 int *type)
48 {
49 	struct page *page = NOPAGE_SIGBUS;
50 	sigset_t blocked, oldset;
51 	int ret;
52 
53 	mlog_entry("(area=%p, address=%lu, type=%p)\n", area, address,
54 		   type);
55 
56 	/* The best way to deal with signals in this path is
57 	 * to block them upfront, rather than allowing the
58 	 * locking paths to return -ERESTARTSYS. */
59 	sigfillset(&blocked);
60 
61 	/* We should technically never get a bad ret return
62 	 * from sigprocmask */
63 	ret = sigprocmask(SIG_BLOCK, &blocked, &oldset);
64 	if (ret < 0) {
65 		mlog_errno(ret);
66 		goto out;
67 	}
68 
69 	page = filemap_nopage(area, address, type);
70 
71 	ret = sigprocmask(SIG_SETMASK, &oldset, NULL);
72 	if (ret < 0)
73 		mlog_errno(ret);
74 out:
75 	mlog_exit_ptr(page);
76 	return page;
77 }
78 
79 static struct vm_operations_struct ocfs2_file_vm_ops = {
80 	.nopage = ocfs2_nopage,
81 };
82 
83 int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
84 {
85 	int ret = 0, lock_level = 0;
86 	struct ocfs2_super *osb = OCFS2_SB(file->f_dentry->d_inode->i_sb);
87 
88 	/*
89 	 * Only support shared writeable mmap for local mounts which
90 	 * don't know about holes.
91 	 */
92 	if ((!ocfs2_mount_local(osb) || ocfs2_sparse_alloc(osb)) &&
93 	    ((vma->vm_flags & VM_SHARED) || (vma->vm_flags & VM_MAYSHARE)) &&
94 	    ((vma->vm_flags & VM_WRITE) || (vma->vm_flags & VM_MAYWRITE))) {
95 		mlog(0, "disallow shared writable mmaps %lx\n", vma->vm_flags);
96 		/* This is -EINVAL because generic_file_readonly_mmap
97 		 * returns it in a similar situation. */
98 		return -EINVAL;
99 	}
100 
101 	ret = ocfs2_meta_lock_atime(file->f_dentry->d_inode,
102 				    file->f_vfsmnt, &lock_level);
103 	if (ret < 0) {
104 		mlog_errno(ret);
105 		goto out;
106 	}
107 	ocfs2_meta_unlock(file->f_dentry->d_inode, lock_level);
108 out:
109 	vma->vm_ops = &ocfs2_file_vm_ops;
110 	return 0;
111 }
112 
113