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 <linux/buffer_head.h>
  29 #include "ext2.h"
  30 #include "xattr.h"
  31 #include "acl.h"
  32 #include "trace.h"
  33
  34 #ifdef CONFIG_FS_DAX
  35 static ssize_t ext2_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
  36 {
  37         struct inode *inode = iocb->ki_filp->f_mapping->host;
  38         ssize_t ret;
  39
  40         if (!iov_iter_count(to))
  41                 return 0; /* skip atime */
  42
  43         inode_lock_shared(inode);
  44         ret = dax_iomap_rw(iocb, to, &ext2_iomap_ops);
  45         inode_unlock_shared(inode);
  46
  47         file_accessed(iocb->ki_filp);
  48         return ret;
  49 }
  50
  51 static ssize_t ext2_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
  52 {
  53         struct file *file = iocb->ki_filp;
  54         struct inode *inode = file->f_mapping->host;
  55         ssize_t ret;
  56
  57         inode_lock(inode);
  58         ret = generic_write_checks(iocb, from);
  59         if (ret <= 0)
  60                 goto out_unlock;
  61         ret = file_remove_privs(file);
  62         if (ret)
  63                 goto out_unlock;
  64         ret = file_update_time(file);
  65         if (ret)
  66                 goto out_unlock;
  67
  68         ret = dax_iomap_rw(iocb, from, &ext2_iomap_ops);
  69         if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
  70                 i_size_write(inode, iocb->ki_pos);
  71                 mark_inode_dirty(inode);
  72         }
  73
  74 out_unlock:
  75         inode_unlock(inode);
  76         if (ret > 0)
  77                 ret = generic_write_sync(iocb, ret);
  78         return ret;
  79 }
  80
  81 /*
  82  * The lock ordering for ext2 DAX fault paths is:
  83  *
  84  * mmap_lock (MM)
  85  *   sb_start_pagefault (vfs, freeze)
  86  *     address_space->invalidate_lock
  87  *       address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
  88  *         ext2_inode_info->truncate_mutex
  89  *
  90  * The default page_lock and i_size verification done by non-DAX fault paths
  91  * is sufficient because ext2 doesn't support hole punching.
  92  */
  93 static vm_fault_t ext2_dax_fault(struct vm_fault *vmf)
  94 {
  95         struct inode *inode = file_inode(vmf->vma->vm_file);
  96         vm_fault_t ret;
  97         bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
  98                 (vmf->vma->vm_flags & VM_SHARED);
  99
 100         if (write) {
 101                 sb_start_pagefault(inode->i_sb);
 102                 file_update_time(vmf->vma->vm_file);
 103         }
 104         filemap_invalidate_lock_shared(inode->i_mapping);
 105
 106         ret = dax_iomap_fault(vmf, 0, NULL, NULL, &ext2_iomap_ops);
 107
 108         filemap_invalidate_unlock_shared(inode->i_mapping);
 109         if (write)
 110                 sb_end_pagefault(inode->i_sb);
 111         return ret;
 112 }
 113
 114 static const struct vm_operations_struct ext2_dax_vm_ops = {
 115         .fault          = ext2_dax_fault,
 116         /*
 117          * .huge_fault is not supported for DAX because allocation in ext2
 118          * cannot be reliably aligned to huge page sizes and so pmd faults
 119          * will always fail and fail back to regular faults.
 120          */
 121         .page_mkwrite   = ext2_dax_fault,
 122         .pfn_mkwrite    = ext2_dax_fault,
 123 };
 124
 125 static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
 126 {
 127         if (!IS_DAX(file_inode(file)))
 128                 return generic_file_mmap(file, vma);
 129
 130         file_accessed(file);
 131         vma->vm_ops = &ext2_dax_vm_ops;
 132         return 0;
 133 }
 134 #else
 135 #define ext2_file_mmap  generic_file_mmap
 136 #endif
 137
 138 /*
 139  * Called when filp is released. This happens when all file descriptors
 140  * for a single struct file are closed. Note that different open() calls
 141  * for the same file yield different struct file structures.
 142  */
 143 static int ext2_release_file (struct inode * inode, struct file * filp)
 144 {
 145         if (filp->f_mode & FMODE_WRITE) {
 146                 mutex_lock(&EXT2_I(inode)->truncate_mutex);
 147                 ext2_discard_reservation(inode);
 148                 mutex_unlock(&EXT2_I(inode)->truncate_mutex);
 149         }
 150         return 0;
 151 }
 152
 153 int ext2_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 154 {
 155         int ret;
 156         struct super_block *sb = file->f_mapping->host->i_sb;
 157
 158         ret = generic_buffers_fsync(file, start, end, datasync);
 159         if (ret == -EIO)
 160                 /* We don't really know where the IO error happened... */
 161                 ext2_error(sb, __func__,
 162                            "detected IO error when writing metadata buffers");
 163         return ret;
 164 }
 165
 166 static ssize_t ext2_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
 167 {
 168         struct file *file = iocb->ki_filp;
 169         struct inode *inode = file->f_mapping->host;
 170         ssize_t ret;
 171
 172         trace_ext2_dio_read_begin(iocb, to, 0);
 173         inode_lock_shared(inode);
 174         ret = iomap_dio_rw(iocb, to, &ext2_iomap_ops, NULL, 0, NULL, 0);
 175         inode_unlock_shared(inode);
 176         trace_ext2_dio_read_end(iocb, to, ret);
 177
 178         return ret;
 179 }
 180
 181 static int ext2_dio_write_end_io(struct kiocb *iocb, ssize_t size,
 182                                  int error, unsigned int flags)
 183 {
 184         loff_t pos = iocb->ki_pos;
 185         struct inode *inode = file_inode(iocb->ki_filp);
 186
 187         if (error)
 188                 goto out;
 189
 190         /*
 191          * If we are extending the file, we have to update i_size here before
 192          * page cache gets invalidated in iomap_dio_rw(). This prevents racing
 193          * buffered reads from zeroing out too much from page cache pages.
 194          * Note that all extending writes always happens synchronously with
 195          * inode lock held by ext2_dio_write_iter(). So it is safe to update
 196          * inode size here for extending file writes.
 197          */
 198         pos += size;
 199         if (pos > i_size_read(inode)) {
 200                 i_size_write(inode, pos);
 201                 mark_inode_dirty(inode);
 202         }
 203 out:
 204         trace_ext2_dio_write_endio(iocb, size, error);
 205         return error;
 206 }
 207
 208 static const struct iomap_dio_ops ext2_dio_write_ops = {
 209         .end_io = ext2_dio_write_end_io,
 210 };
 211
 212 static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 213 {
 214         struct file *file = iocb->ki_filp;
 215         struct inode *inode = file->f_mapping->host;
 216         ssize_t ret;
 217         unsigned int flags = 0;
 218         unsigned long blocksize = inode->i_sb->s_blocksize;
 219         loff_t offset = iocb->ki_pos;
 220         loff_t count = iov_iter_count(from);
 221         ssize_t status = 0;
 222
 223         trace_ext2_dio_write_begin(iocb, from, 0);
 224         inode_lock(inode);
 225         ret = generic_write_checks(iocb, from);
 226         if (ret <= 0)
 227                 goto out_unlock;
 228
 229         ret = kiocb_modified(iocb);
 230         if (ret)
 231                 goto out_unlock;
 232
 233         /* use IOMAP_DIO_FORCE_WAIT for unaligned or extending writes */
 234         if (iocb->ki_pos + iov_iter_count(from) > i_size_read(inode) ||
 235            (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(from), blocksize)))
 236                 flags |= IOMAP_DIO_FORCE_WAIT;
 237
 238         ret = iomap_dio_rw(iocb, from, &ext2_iomap_ops, &ext2_dio_write_ops,
 239                            flags, NULL, 0);
 240
 241         /* ENOTBLK is magic return value for fallback to buffered-io */
 242         if (ret == -ENOTBLK)
 243                 ret = 0;
 244
 245         if (ret < 0 && ret != -EIOCBQUEUED)
 246                 ext2_write_failed(inode->i_mapping, offset + count);
 247
 248         /* handle case for partial write and for fallback to buffered write */
 249         if (ret >= 0 && iov_iter_count(from)) {
 250                 loff_t pos, endbyte;
 251                 int ret2;
 252
 253                 iocb->ki_flags &= ~IOCB_DIRECT;
 254                 pos = iocb->ki_pos;
 255                 status = generic_perform_write(iocb, from);
 256                 if (unlikely(status < 0)) {
 257                         ret = status;
 258                         goto out_unlock;
 259                 }
 260
 261                 iocb->ki_pos += status;
 262                 ret += status;
 263                 endbyte = pos + status - 1;
 264                 ret2 = filemap_write_and_wait_range(inode->i_mapping, pos,
 265                                                     endbyte);
 266                 if (!ret2)
 267                         invalidate_mapping_pages(inode->i_mapping,
 268                                                  pos >> PAGE_SHIFT,
 269                                                  endbyte >> PAGE_SHIFT);
 270                 if (ret > 0)
 271                         generic_write_sync(iocb, ret);
 272         }
 273
 274 out_unlock:
 275         inode_unlock(inode);
 276         if (status)
 277                 trace_ext2_dio_write_buff_end(iocb, from, status);
 278         trace_ext2_dio_write_end(iocb, from, ret);
 279         return ret;
 280 }
 281
 282 static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 283 {
 284 #ifdef CONFIG_FS_DAX
 285         if (IS_DAX(iocb->ki_filp->f_mapping->host))
 286                 return ext2_dax_read_iter(iocb, to);
 287 #endif
 288         if (iocb->ki_flags & IOCB_DIRECT)
 289                 return ext2_dio_read_iter(iocb, to);
 290
 291         return generic_file_read_iter(iocb, to);
 292 }
 293
 294 static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 295 {
 296 #ifdef CONFIG_FS_DAX
 297         if (IS_DAX(iocb->ki_filp->f_mapping->host))
 298                 return ext2_dax_write_iter(iocb, from);
 299 #endif
 300         if (iocb->ki_flags & IOCB_DIRECT)
 301                 return ext2_dio_write_iter(iocb, from);
 302
 303         return generic_file_write_iter(iocb, from);
 304 }
 305
 306 const struct file_operations ext2_file_operations = {
 307         .llseek         = generic_file_llseek,
 308         .read_iter      = ext2_file_read_iter,
 309         .write_iter     = ext2_file_write_iter,
 310         .unlocked_ioctl = ext2_ioctl,
 311 #ifdef CONFIG_COMPAT
 312         .compat_ioctl   = ext2_compat_ioctl,
 313 #endif
 314         .mmap           = ext2_file_mmap,
 315         .open           = dquot_file_open,
 316         .release        = ext2_release_file,
 317         .fsync          = ext2_fsync,
 318         .get_unmapped_area = thp_get_unmapped_area,
 319         .splice_read    = filemap_splice_read,
 320         .splice_write   = iter_file_splice_write,
 321 };
 322
 323 const struct inode_operations ext2_file_inode_operations = {
 324         .listxattr      = ext2_listxattr,
 325         .getattr        = ext2_getattr,
 326         .setattr        = ext2_setattr,
 327         .get_inode_acl  = ext2_get_acl,
 328         .set_acl        = ext2_set_acl,
 329         .fiemap         = ext2_fiemap,
 330         .fileattr_get   = ext2_fileattr_get,
 331         .fileattr_set   = ext2_fileattr_set,
 332 };