fs/ocfs2/mmap.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* -*- mode: c; c-basic-offset: 8; -*-
   3  * vim: noexpandtab sw=8 ts=8 sts=0:
   4  *
   5  * mmap.c
   6  *
   7  * Code to deal with the mess that is clustered mmap.
   8  *
   9  * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
  10  */
  11
  12 #include <linux/fs.h>
  13 #include <linux/types.h>
  14 #include <linux/highmem.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/uio.h>
  17 #include <linux/signal.h>
  18 #include <linux/rbtree.h>
  19
  20 #include <cluster/masklog.h>
  21
  22 #include "ocfs2.h"
  23
  24 #include "aops.h"
  25 #include "dlmglue.h"
  26 #include "file.h"
  27 #include "inode.h"
  28 #include "mmap.h"
  29 #include "super.h"
  30 #include "ocfs2_trace.h"
  31
  32
  33 static vm_fault_t ocfs2_fault(struct vm_fault *vmf)
  34 {
  35         struct vm_area_struct *vma = vmf->vma;
  36         sigset_t oldset;
  37         vm_fault_t ret;
  38
  39         ocfs2_block_signals(&oldset);
  40         ret = filemap_fault(vmf);
  41         ocfs2_unblock_signals(&oldset);
  42
  43         trace_ocfs2_fault(OCFS2_I(vma->vm_file->f_mapping->host)->ip_blkno,
  44                           vma, vmf->page, vmf->pgoff);
  45         return ret;
  46 }
  47
  48 static vm_fault_t __ocfs2_page_mkwrite(struct file *file,
  49                         struct buffer_head *di_bh, struct page *page)
  50 {
  51         int err;
  52         vm_fault_t ret = VM_FAULT_NOPAGE;
  53         struct inode *inode = file_inode(file);
  54         struct address_space *mapping = inode->i_mapping;
  55         loff_t pos = page_offset(page);
  56         unsigned int len = PAGE_SIZE;
  57         pgoff_t last_index;
  58         struct page *locked_page = NULL;
  59         void *fsdata;
  60         loff_t size = i_size_read(inode);
  61
  62         last_index = (size - 1) >> PAGE_SHIFT;
  63
  64         /*
  65          * There are cases that lead to the page no longer bebongs to the
  66          * mapping.
  67          * 1) pagecache truncates locally due to memory pressure.
  68          * 2) pagecache truncates when another is taking EX lock against
  69          * inode lock. see ocfs2_data_convert_worker.
  70          *
  71          * The i_size check doesn't catch the case where nodes truncated and
  72          * then re-extended the file. We'll re-check the page mapping after
  73          * taking the page lock inside of ocfs2_write_begin_nolock().
  74          *
  75          * Let VM retry with these cases.
  76          */
  77         if ((page->mapping != inode->i_mapping) ||
  78             (!PageUptodate(page)) ||
  79             (page_offset(page) >= size))
  80                 goto out;
  81
  82         /*
  83          * Call ocfs2_write_begin() and ocfs2_write_end() to take
  84          * advantage of the allocation code there. We pass a write
  85          * length of the whole page (chopped to i_size) to make sure
  86          * the whole thing is allocated.
  87          *
  88          * Since we know the page is up to date, we don't have to
  89          * worry about ocfs2_write_begin() skipping some buffer reads
  90          * because the "write" would invalidate their data.
  91          */
  92         if (page->index == last_index)
  93                 len = ((size - 1) & ~PAGE_MASK) + 1;
  94
  95         err = ocfs2_write_begin_nolock(mapping, pos, len, OCFS2_WRITE_MMAP,
  96                                        &locked_page, &fsdata, di_bh, page);
  97         if (err) {
  98                 if (err != -ENOSPC)
  99                         mlog_errno(err);
 100                 ret = vmf_error(err);
 101                 goto out;
 102         }
 103
 104         if (!locked_page) {
 105                 ret = VM_FAULT_NOPAGE;
 106                 goto out;
 107         }
 108         err = ocfs2_write_end_nolock(mapping, pos, len, len, fsdata);
 109         BUG_ON(err != len);
 110         ret = VM_FAULT_LOCKED;
 111 out:
 112         return ret;
 113 }
 114
 115 static vm_fault_t ocfs2_page_mkwrite(struct vm_fault *vmf)
 116 {
 117         struct page *page = vmf->page;
 118         struct inode *inode = file_inode(vmf->vma->vm_file);
 119         struct buffer_head *di_bh = NULL;
 120         sigset_t oldset;
 121         int err;
 122         vm_fault_t ret;
 123
 124         sb_start_pagefault(inode->i_sb);
 125         ocfs2_block_signals(&oldset);
 126
 127         /*
 128          * The cluster locks taken will block a truncate from another
 129          * node. Taking the data lock will also ensure that we don't
 130          * attempt page truncation as part of a downconvert.
 131          */
 132         err = ocfs2_inode_lock(inode, &di_bh, 1);
 133         if (err < 0) {
 134                 mlog_errno(err);
 135                 ret = vmf_error(err);
 136                 goto out;
 137         }
 138
 139         /*
 140          * The alloc sem should be enough to serialize with
 141          * ocfs2_truncate_file() changing i_size as well as any thread
 142          * modifying the inode btree.
 143          */
 144         down_write(&OCFS2_I(inode)->ip_alloc_sem);
 145
 146         ret = __ocfs2_page_mkwrite(vmf->vma->vm_file, di_bh, page);
 147
 148         up_write(&OCFS2_I(inode)->ip_alloc_sem);
 149
 150         brelse(di_bh);
 151         ocfs2_inode_unlock(inode, 1);
 152
 153 out:
 154         ocfs2_unblock_signals(&oldset);
 155         sb_end_pagefault(inode->i_sb);
 156         return ret;
 157 }
 158
 159 static const struct vm_operations_struct ocfs2_file_vm_ops = {
 160         .fault          = ocfs2_fault,
 161         .page_mkwrite   = ocfs2_page_mkwrite,
 162 };
 163
 164 int ocfs2_mmap(struct file *file, struct vm_area_struct *vma)
 165 {
 166         int ret = 0, lock_level = 0;
 167
 168         ret = ocfs2_inode_lock_atime(file_inode(file),
 169                                     file->f_path.mnt, &lock_level, 1);
 170         if (ret < 0) {
 171                 mlog_errno(ret);
 172                 goto out;
 173         }
 174         ocfs2_inode_unlock(file_inode(file), lock_level);
 175 out:
 176         vma->vm_ops = &ocfs2_file_vm_ops;
 177         return 0;
 178 }
 179