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
  31 static 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
  46 static 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 folio *locked_folio = 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_folio, &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_folio) {
 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;
 109 out:
 110         return ret;
 111 }
 112
 113 static 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
 151 out:
 152         ocfs2_unblock_signals(&oldset);
 153         sb_end_pagefault(inode->i_sb);
 154         return ret;
 155 }
 156
 157 static const struct vm_operations_struct ocfs2_file_vm_ops = {
 158         .fault          = ocfs2_fault,
 159         .page_mkwrite   = ocfs2_page_mkwrite,
 160 };
 161
 162 int 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);
 173 out:
 174         vma->vm_ops = &ocfs2_file_vm_ops;
 175         return 0;
 176 }
 177