LXR linux/fs/ocfs2/mmap.c

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