release/src-rt-6.x/linux/linux-2.6/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 int ocfs2_fault(struct vm_area_struct *area, struct vm_fault *vmf)
  46 {
  47         sigset_t blocked, oldset;
  48         int error, ret;
  49
  50         mlog_entry("(area=%p, page offset=%lu)\n", area, vmf->pgoff);
  51
  52         /* The best way to deal with signals in this path is
  53          * to block them upfront, rather than allowing the
  54          * locking paths to return -ERESTARTSYS. */
  55         sigfillset(&blocked);
  56
  57         /* We should technically never get a bad ret return
  58          * from sigprocmask */
  59         error = sigprocmask(SIG_BLOCK, &blocked, &oldset);
  60         if (ret < 0) {
  61                 mlog_errno(error);
  62                 ret = VM_FAULT_SIGBUS;
  63                 goto out;
  64         }
  65
  66         ret = filemap_fault(area, vmf);
  67
  68         error = sigprocmask(SIG_SETMASK, &oldset, NULL);
  69         if (error < 0)
  70                 mlog_errno(error);
  71 out:
  72         mlog_exit_ptr(vmf->page);
  73         return ret;
  74 }
  75
  76 static struct vm_operations_struct ocfs2_file_vm_ops = {
  77         .fault          = ocfs2_fault,
  78 };
  79
  80 int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
  81 {
  82         int ret = 0, lock_level = 0;
  83         struct ocfs2_super *osb = OCFS2_SB(file->f_dentry->d_inode->i_sb);
  84
  85         /*
  86          * Only support shared writeable mmap for local mounts which
  87          * don't know about holes.
  88          */
  89         if ((!ocfs2_mount_local(osb) || ocfs2_sparse_alloc(osb)) &&
  90             ((vma->vm_flags & VM_SHARED) || (vma->vm_flags & VM_MAYSHARE)) &&
  91             ((vma->vm_flags & VM_WRITE) || (vma->vm_flags & VM_MAYWRITE))) {
  92                 mlog(0, "disallow shared writable mmaps %lx\n", vma->vm_flags);
  93                 /* This is -EINVAL because generic_file_readonly_mmap
  94                  * returns it in a similar situation. */
  95                 return -EINVAL;
  96         }
  97
  98         ret = ocfs2_meta_lock_atime(file->f_dentry->d_inode,
  99                                     file->f_vfsmnt, &lock_level);
 100         if (ret < 0) {
 101                 mlog_errno(ret);
 102                 goto out;
 103         }
 104         ocfs2_meta_unlock(file->f_dentry->d_inode, lock_level);
 105 out:
 106         vma->vm_ops = &ocfs2_file_vm_ops;
 107         vma->vm_flags |= VM_CAN_NONLINEAR;
 108         return 0;
 109 }
 110