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/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