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Linux/fs/ocfs2/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_inode(file);
 66         struct address_space *mapping = inode->i_mapping;
 67         loff_t pos = page_offset(page);
 68         unsigned int len = PAGE_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_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_MASK) + 1;
106 
107         ret = ocfs2_write_begin_nolock(mapping, pos, len, OCFS2_WRITE_MMAP,
108                                        &locked_page, &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 = file_inode(vma->vm_file);
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                 if (ret == -ENOMEM)
151                         ret = VM_FAULT_OOM;
152                 else
153                         ret = VM_FAULT_SIGBUS;
154                 goto out;
155         }
156 
157         /*
158          * The alloc sem should be enough to serialize with
159          * ocfs2_truncate_file() changing i_size as well as any thread
160          * modifying the inode btree.
161          */
162         down_write(&OCFS2_I(inode)->ip_alloc_sem);
163 
164         ret = __ocfs2_page_mkwrite(vma->vm_file, di_bh, page);
165 
166         up_write(&OCFS2_I(inode)->ip_alloc_sem);
167 
168         brelse(di_bh);
169         ocfs2_inode_unlock(inode, 1);
170 
171 out:
172         ocfs2_unblock_signals(&oldset);
173         sb_end_pagefault(inode->i_sb);
174         return ret;
175 }
176 
177 static const struct vm_operations_struct ocfs2_file_vm_ops = {
178         .fault          = ocfs2_fault,
179         .page_mkwrite   = ocfs2_page_mkwrite,
180 };
181 
182 int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
183 {
184         int ret = 0, lock_level = 0;
185 
186         ret = ocfs2_inode_lock_atime(file_inode(file),
187                                     file->f_path.mnt, &lock_level);
188         if (ret < 0) {
189                 mlog_errno(ret);
190                 goto out;
191         }
192         ocfs2_inode_unlock(file_inode(file), lock_level);
193 out:
194         vma->vm_ops = &ocfs2_file_vm_ops;
195         return 0;
196 }
197 
198 

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