fs/nilfs2/file.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * file.c - NILFS regular file handling primitives including fsync().
   4  *
   5  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   6  *
   7  * Written by Amagai Yoshiji and Ryusuke Konishi.
   8  */
   9
  10 #include <linux/fs.h>
  11 #include <linux/mm.h>
  12 #include <linux/writeback.h>
  13 #include "nilfs.h"
  14 #include "segment.h"
  15
  16 int nilfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
  17 {
  18         /*
  19          * Called from fsync() system call
  20          * This is the only entry point that can catch write and synch
  21          * timing for both data blocks and intermediate blocks.
  22          *
  23          * This function should be implemented when the writeback function
  24          * will be implemented.
  25          */
  26         struct the_nilfs *nilfs;
  27         struct inode *inode = file->f_mapping->host;
  28         int err = 0;
  29
  30         if (nilfs_inode_dirty(inode)) {
  31                 if (datasync)
  32                         err = nilfs_construct_dsync_segment(inode->i_sb, inode,
  33                                                             start, end);
  34                 else
  35                         err = nilfs_construct_segment(inode->i_sb);
  36         }
  37
  38         nilfs = inode->i_sb->s_fs_info;
  39         if (!err)
  40                 err = nilfs_flush_device(nilfs);
  41
  42         return err;
  43 }
  44
  45 static vm_fault_t nilfs_page_mkwrite(struct vm_fault *vmf)
  46 {
  47         struct vm_area_struct *vma = vmf->vma;
  48         struct page *page = vmf->page;
  49         struct inode *inode = file_inode(vma->vm_file);
  50         struct nilfs_transaction_info ti;
  51         int ret = 0;
  52
  53         if (unlikely(nilfs_near_disk_full(inode->i_sb->s_fs_info)))
  54                 return VM_FAULT_SIGBUS; /* -ENOSPC */
  55
  56         sb_start_pagefault(inode->i_sb);
  57         lock_page(page);
  58         if (page->mapping != inode->i_mapping ||
  59             page_offset(page) >= i_size_read(inode) || !PageUptodate(page)) {
  60                 unlock_page(page);
  61                 ret = -EFAULT;  /* make the VM retry the fault */
  62                 goto out;
  63         }
  64
  65         /*
  66          * check to see if the page is mapped already (no holes)
  67          */
  68         if (PageMappedToDisk(page))
  69                 goto mapped;
  70
  71         if (page_has_buffers(page)) {
  72                 struct buffer_head *bh, *head;
  73                 int fully_mapped = 1;
  74
  75                 bh = head = page_buffers(page);
  76                 do {
  77                         if (!buffer_mapped(bh)) {
  78                                 fully_mapped = 0;
  79                                 break;
  80                         }
  81                 } while (bh = bh->b_this_page, bh != head);
  82
  83                 if (fully_mapped) {
  84                         SetPageMappedToDisk(page);
  85                         goto mapped;
  86                 }
  87         }
  88         unlock_page(page);
  89
  90         /*
  91          * fill hole blocks
  92          */
  93         ret = nilfs_transaction_begin(inode->i_sb, &ti, 1);
  94         /* never returns -ENOMEM, but may return -ENOSPC */
  95         if (unlikely(ret))
  96                 goto out;
  97
  98         file_update_time(vma->vm_file);
  99         ret = block_page_mkwrite(vma, vmf, nilfs_get_block);
 100         if (ret) {
 101                 nilfs_transaction_abort(inode->i_sb);
 102                 goto out;
 103         }
 104         nilfs_set_file_dirty(inode, 1 << (PAGE_SHIFT - inode->i_blkbits));
 105         nilfs_transaction_commit(inode->i_sb);
 106
 107  mapped:
 108         wait_for_stable_page(page);
 109  out:
 110         sb_end_pagefault(inode->i_sb);
 111         return block_page_mkwrite_return(ret);
 112 }
 113
 114 static const struct vm_operations_struct nilfs_file_vm_ops = {
 115         .fault          = filemap_fault,
 116         .map_pages      = filemap_map_pages,
 117         .page_mkwrite   = nilfs_page_mkwrite,
 118 };
 119
 120 static int nilfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 121 {
 122         file_accessed(file);
 123         vma->vm_ops = &nilfs_file_vm_ops;
 124         return 0;
 125 }
 126
 127 /*
 128  * We have mostly NULL's here: the current defaults are ok for
 129  * the nilfs filesystem.
 130  */
 131 const struct file_operations nilfs_file_operations = {
 132         .llseek         = generic_file_llseek,
 133         .read_iter      = generic_file_read_iter,
 134         .write_iter     = generic_file_write_iter,
 135         .unlocked_ioctl = nilfs_ioctl,
 136 #ifdef CONFIG_COMPAT
 137         .compat_ioctl   = nilfs_compat_ioctl,
 138 #endif  /* CONFIG_COMPAT */
 139         .mmap           = nilfs_file_mmap,
 140         .open           = generic_file_open,
 141         /* .release     = nilfs_release_file, */
 142         .fsync          = nilfs_sync_file,
 143         .splice_read    = generic_file_splice_read,
 144 };
 145
 146 const struct inode_operations nilfs_file_inode_operations = {
 147         .setattr        = nilfs_setattr,
 148         .permission     = nilfs_permission,
 149         .fiemap         = nilfs_fiemap,
 150 };
 151
 152 /* end of file */