fs/ext2/file.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/ext2/file.c
   4  *
   5  * Copyright (C) 1992, 1993, 1994, 1995
   6  * Remy Card (card@masi.ibp.fr)
   7  * Laboratoire MASI - Institut Blaise Pascal
   8  * Universite Pierre et Marie Curie (Paris VI)
   9  *
  10  *  from
  11  *
  12  *  linux/fs/minix/file.c
  13  *
  14  *  Copyright (C) 1991, 1992  Linus Torvalds
  15  *
  16  *  ext2 fs regular file handling primitives
  17  *
  18  *  64-bit file support on 64-bit platforms by Jakub Jelinek
  19  *      (jj@sunsite.ms.mff.cuni.cz)
  20  */
  21
  22 #include <linux/time.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/dax.h>
  25 #include <linux/quotaops.h>
  26 #include <linux/iomap.h>
  27 #include <linux/uio.h>
  28 #include "ext2.h"
  29 #include "xattr.h"
  30 #include "acl.h"
  31
  32 #ifdef CONFIG_FS_DAX
  33 static ssize_t ext2_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
  34 {
  35         struct inode *inode = iocb->ki_filp->f_mapping->host;
  36         ssize_t ret;
  37
  38         if (!iov_iter_count(to))
  39                 return 0; /* skip atime */
  40
  41         inode_lock_shared(inode);
  42         ret = dax_iomap_rw(iocb, to, &ext2_iomap_ops);
  43         inode_unlock_shared(inode);
  44
  45         file_accessed(iocb->ki_filp);
  46         return ret;
  47 }
  48
  49 static ssize_t ext2_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
  50 {
  51         struct file *file = iocb->ki_filp;
  52         struct inode *inode = file->f_mapping->host;
  53         ssize_t ret;
  54
  55         inode_lock(inode);
  56         ret = generic_write_checks(iocb, from);
  57         if (ret <= 0)
  58                 goto out_unlock;
  59         ret = file_remove_privs(file);
  60         if (ret)
  61                 goto out_unlock;
  62         ret = file_update_time(file);
  63         if (ret)
  64                 goto out_unlock;
  65
  66         ret = dax_iomap_rw(iocb, from, &ext2_iomap_ops);
  67         if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
  68                 i_size_write(inode, iocb->ki_pos);
  69                 mark_inode_dirty(inode);
  70         }
  71
  72 out_unlock:
  73         inode_unlock(inode);
  74         if (ret > 0)
  75                 ret = generic_write_sync(iocb, ret);
  76         return ret;
  77 }
  78
  79 /*
  80  * The lock ordering for ext2 DAX fault paths is:
  81  *
  82  * mmap_lock (MM)
  83  *   sb_start_pagefault (vfs, freeze)
  84  *     ext2_inode_info->dax_sem
  85  *       address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
  86  *         ext2_inode_info->truncate_mutex
  87  *
  88  * The default page_lock and i_size verification done by non-DAX fault paths
  89  * is sufficient because ext2 doesn't support hole punching.
  90  */
  91 static vm_fault_t ext2_dax_fault(struct vm_fault *vmf)
  92 {
  93         struct inode *inode = file_inode(vmf->vma->vm_file);
  94         struct ext2_inode_info *ei = EXT2_I(inode);
  95         vm_fault_t ret;
  96         bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
  97                 (vmf->vma->vm_flags & VM_SHARED);
  98
  99         if (write) {
 100                 sb_start_pagefault(inode->i_sb);
 101                 file_update_time(vmf->vma->vm_file);
 102         }
 103         down_read(&ei->dax_sem);
 104
 105         ret = dax_iomap_fault(vmf, PE_SIZE_PTE, NULL, NULL, &ext2_iomap_ops);
 106
 107         up_read(&ei->dax_sem);
 108         if (write)
 109                 sb_end_pagefault(inode->i_sb);
 110         return ret;
 111 }
 112
 113 static const struct vm_operations_struct ext2_dax_vm_ops = {
 114         .fault          = ext2_dax_fault,
 115         /*
 116          * .huge_fault is not supported for DAX because allocation in ext2
 117          * cannot be reliably aligned to huge page sizes and so pmd faults
 118          * will always fail and fail back to regular faults.
 119          */
 120         .page_mkwrite   = ext2_dax_fault,
 121         .pfn_mkwrite    = ext2_dax_fault,
 122 };
 123
 124 static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
 125 {
 126         if (!IS_DAX(file_inode(file)))
 127                 return generic_file_mmap(file, vma);
 128
 129         file_accessed(file);
 130         vma->vm_ops = &ext2_dax_vm_ops;
 131         return 0;
 132 }
 133 #else
 134 #define ext2_file_mmap  generic_file_mmap
 135 #endif
 136
 137 /*
 138  * Called when filp is released. This happens when all file descriptors
 139  * for a single struct file are closed. Note that different open() calls
 140  * for the same file yield different struct file structures.
 141  */
 142 static int ext2_release_file (struct inode * inode, struct file * filp)
 143 {
 144         if (filp->f_mode & FMODE_WRITE) {
 145                 mutex_lock(&EXT2_I(inode)->truncate_mutex);
 146                 ext2_discard_reservation(inode);
 147                 mutex_unlock(&EXT2_I(inode)->truncate_mutex);
 148         }
 149         return 0;
 150 }
 151
 152 int ext2_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 153 {
 154         int ret;
 155         struct super_block *sb = file->f_mapping->host->i_sb;
 156
 157         ret = generic_file_fsync(file, start, end, datasync);
 158         if (ret == -EIO)
 159                 /* We don't really know where the IO error happened... */
 160                 ext2_error(sb, __func__,
 161                            "detected IO error when writing metadata buffers");
 162         return ret;
 163 }
 164
 165 static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 166 {
 167 #ifdef CONFIG_FS_DAX
 168         if (IS_DAX(iocb->ki_filp->f_mapping->host))
 169                 return ext2_dax_read_iter(iocb, to);
 170 #endif
 171         return generic_file_read_iter(iocb, to);
 172 }
 173
 174 static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 175 {
 176 #ifdef CONFIG_FS_DAX
 177         if (IS_DAX(iocb->ki_filp->f_mapping->host))
 178                 return ext2_dax_write_iter(iocb, from);
 179 #endif
 180         return generic_file_write_iter(iocb, from);
 181 }
 182
 183 const struct file_operations ext2_file_operations = {
 184         .llseek         = generic_file_llseek,
 185         .read_iter      = ext2_file_read_iter,
 186         .write_iter     = ext2_file_write_iter,
 187         .unlocked_ioctl = ext2_ioctl,
 188 #ifdef CONFIG_COMPAT
 189         .compat_ioctl   = ext2_compat_ioctl,
 190 #endif
 191         .mmap           = ext2_file_mmap,
 192         .open           = dquot_file_open,
 193         .release        = ext2_release_file,
 194         .fsync          = ext2_fsync,
 195         .get_unmapped_area = thp_get_unmapped_area,
 196         .splice_read    = generic_file_splice_read,
 197         .splice_write   = iter_file_splice_write,
 198 };
 199
 200 const struct inode_operations ext2_file_inode_operations = {
 201         .listxattr      = ext2_listxattr,
 202         .getattr        = ext2_getattr,
 203         .setattr        = ext2_setattr,
 204         .get_acl        = ext2_get_acl,
 205         .set_acl        = ext2_set_acl,
 206         .fiemap         = ext2_fiemap,
 207         .fileattr_get   = ext2_fileattr_get,
 208         .fileattr_set   = ext2_fileattr_set,
 209 };