fs/ext4/file.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/ext4/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  *  ext4 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/fs.h>
  24 #include <linux/iomap.h>
  25 #include <linux/mount.h>
  26 #include <linux/path.h>
  27 #include <linux/dax.h>
  28 #include <linux/quotaops.h>
  29 #include <linux/pagevec.h>
  30 #include <linux/uio.h>
  31 #include <linux/mman.h>
  32 #include <linux/backing-dev.h>
  33 #include "ext4.h"
  34 #include "ext4_jbd2.h"
  35 #include "xattr.h"
  36 #include "acl.h"
  37 #include "truncate.h"
  38
  39 static bool ext4_dio_supported(struct inode *inode)
  40 {
  41         if (IS_ENABLED(CONFIG_FS_ENCRYPTION) && IS_ENCRYPTED(inode))
  42                 return false;
  43         if (fsverity_active(inode))
  44                 return false;
  45         if (ext4_should_journal_data(inode))
  46                 return false;
  47         if (ext4_has_inline_data(inode))
  48                 return false;
  49         return true;
  50 }
  51
  52 static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
  53 {
  54         ssize_t ret;
  55         struct inode *inode = file_inode(iocb->ki_filp);
  56
  57         if (iocb->ki_flags & IOCB_NOWAIT) {
  58                 if (!inode_trylock_shared(inode))
  59                         return -EAGAIN;
  60         } else {
  61                 inode_lock_shared(inode);
  62         }
  63
  64         if (!ext4_dio_supported(inode)) {
  65                 inode_unlock_shared(inode);
  66                 /*
  67                  * Fallback to buffered I/O if the operation being performed on
  68                  * the inode is not supported by direct I/O. The IOCB_DIRECT
  69                  * flag needs to be cleared here in order to ensure that the
  70                  * direct I/O path within generic_file_read_iter() is not
  71                  * taken.
  72                  */
  73                 iocb->ki_flags &= ~IOCB_DIRECT;
  74                 return generic_file_read_iter(iocb, to);
  75         }
  76
  77         ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL, 0);
  78         inode_unlock_shared(inode);
  79
  80         file_accessed(iocb->ki_filp);
  81         return ret;
  82 }
  83
  84 #ifdef CONFIG_FS_DAX
  85 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
  86 {
  87         struct inode *inode = file_inode(iocb->ki_filp);
  88         ssize_t ret;
  89
  90         if (iocb->ki_flags & IOCB_NOWAIT) {
  91                 if (!inode_trylock_shared(inode))
  92                         return -EAGAIN;
  93         } else {
  94                 inode_lock_shared(inode);
  95         }
  96         /*
  97          * Recheck under inode lock - at this point we are sure it cannot
  98          * change anymore
  99          */
 100         if (!IS_DAX(inode)) {
 101                 inode_unlock_shared(inode);
 102                 /* Fallback to buffered IO in case we cannot support DAX */
 103                 return generic_file_read_iter(iocb, to);
 104         }
 105         ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
 106         inode_unlock_shared(inode);
 107
 108         file_accessed(iocb->ki_filp);
 109         return ret;
 110 }
 111 #endif
 112
 113 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 114 {
 115         struct inode *inode = file_inode(iocb->ki_filp);
 116
 117         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 118                 return -EIO;
 119
 120         if (!iov_iter_count(to))
 121                 return 0; /* skip atime */
 122
 123 #ifdef CONFIG_FS_DAX
 124         if (IS_DAX(inode))
 125                 return ext4_dax_read_iter(iocb, to);
 126 #endif
 127         if (iocb->ki_flags & IOCB_DIRECT)
 128                 return ext4_dio_read_iter(iocb, to);
 129
 130         return generic_file_read_iter(iocb, to);
 131 }
 132
 133 /*
 134  * Called when an inode is released. Note that this is different
 135  * from ext4_file_open: open gets called at every open, but release
 136  * gets called only when /all/ the files are closed.
 137  */
 138 static int ext4_release_file(struct inode *inode, struct file *filp)
 139 {
 140         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
 141                 ext4_alloc_da_blocks(inode);
 142                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
 143         }
 144         /* if we are the last writer on the inode, drop the block reservation */
 145         if ((filp->f_mode & FMODE_WRITE) &&
 146                         (atomic_read(&inode->i_writecount) == 1) &&
 147                         !EXT4_I(inode)->i_reserved_data_blocks) {
 148                 down_write(&EXT4_I(inode)->i_data_sem);
 149                 ext4_discard_preallocations(inode, 0);
 150                 up_write(&EXT4_I(inode)->i_data_sem);
 151         }
 152         if (is_dx(inode) && filp->private_data)
 153                 ext4_htree_free_dir_info(filp->private_data);
 154
 155         return 0;
 156 }
 157
 158 /*
 159  * This tests whether the IO in question is block-aligned or not.
 160  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
 161  * are converted to written only after the IO is complete.  Until they are
 162  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
 163  * it needs to zero out portions of the start and/or end block.  If 2 AIO
 164  * threads are at work on the same unwritten block, they must be synchronized
 165  * or one thread will zero the other's data, causing corruption.
 166  */
 167 static bool
 168 ext4_unaligned_io(struct inode *inode, struct iov_iter *from, loff_t pos)
 169 {
 170         struct super_block *sb = inode->i_sb;
 171         unsigned long blockmask = sb->s_blocksize - 1;
 172
 173         if ((pos | iov_iter_alignment(from)) & blockmask)
 174                 return true;
 175
 176         return false;
 177 }
 178
 179 static bool
 180 ext4_extending_io(struct inode *inode, loff_t offset, size_t len)
 181 {
 182         if (offset + len > i_size_read(inode) ||
 183             offset + len > EXT4_I(inode)->i_disksize)
 184                 return true;
 185         return false;
 186 }
 187
 188 /* Is IO overwriting allocated and initialized blocks? */
 189 static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
 190 {
 191         struct ext4_map_blocks map;
 192         unsigned int blkbits = inode->i_blkbits;
 193         int err, blklen;
 194
 195         if (pos + len > i_size_read(inode))
 196                 return false;
 197
 198         map.m_lblk = pos >> blkbits;
 199         map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
 200         blklen = map.m_len;
 201
 202         err = ext4_map_blocks(NULL, inode, &map, 0);
 203         /*
 204          * 'err==len' means that all of the blocks have been preallocated,
 205          * regardless of whether they have been initialized or not. To exclude
 206          * unwritten extents, we need to check m_flags.
 207          */
 208         return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
 209 }
 210
 211 static ssize_t ext4_generic_write_checks(struct kiocb *iocb,
 212                                          struct iov_iter *from)
 213 {
 214         struct inode *inode = file_inode(iocb->ki_filp);
 215         ssize_t ret;
 216
 217         if (unlikely(IS_IMMUTABLE(inode)))
 218                 return -EPERM;
 219
 220         ret = generic_write_checks(iocb, from);
 221         if (ret <= 0)
 222                 return ret;
 223
 224         /*
 225          * If we have encountered a bitmap-format file, the size limit
 226          * is smaller than s_maxbytes, which is for extent-mapped files.
 227          */
 228         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 229                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 230
 231                 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
 232                         return -EFBIG;
 233                 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
 234         }
 235
 236         return iov_iter_count(from);
 237 }
 238
 239 static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
 240 {
 241         ssize_t ret, count;
 242
 243         count = ext4_generic_write_checks(iocb, from);
 244         if (count <= 0)
 245                 return count;
 246
 247         ret = file_modified(iocb->ki_filp);
 248         if (ret)
 249                 return ret;
 250         return count;
 251 }
 252
 253 static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
 254                                         struct iov_iter *from)
 255 {
 256         ssize_t ret;
 257         struct inode *inode = file_inode(iocb->ki_filp);
 258
 259         if (iocb->ki_flags & IOCB_NOWAIT)
 260                 return -EOPNOTSUPP;
 261
 262         ext4_fc_start_update(inode);
 263         inode_lock(inode);
 264         ret = ext4_write_checks(iocb, from);
 265         if (ret <= 0)
 266                 goto out;
 267
 268         current->backing_dev_info = inode_to_bdi(inode);
 269         ret = generic_perform_write(iocb->ki_filp, from, iocb->ki_pos);
 270         current->backing_dev_info = NULL;
 271
 272 out:
 273         inode_unlock(inode);
 274         ext4_fc_stop_update(inode);
 275         if (likely(ret > 0)) {
 276                 iocb->ki_pos += ret;
 277                 ret = generic_write_sync(iocb, ret);
 278         }
 279
 280         return ret;
 281 }
 282
 283 static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
 284                                            ssize_t written, size_t count)
 285 {
 286         handle_t *handle;
 287         bool truncate = false;
 288         u8 blkbits = inode->i_blkbits;
 289         ext4_lblk_t written_blk, end_blk;
 290         int ret;
 291
 292         /*
 293          * Note that EXT4_I(inode)->i_disksize can get extended up to
 294          * inode->i_size while the I/O was running due to writeback of delalloc
 295          * blocks. But, the code in ext4_iomap_alloc() is careful to use
 296          * zeroed/unwritten extents if this is possible; thus we won't leave
 297          * uninitialized blocks in a file even if we didn't succeed in writing
 298          * as much as we intended.
 299          */
 300         WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize);
 301         if (offset + count <= EXT4_I(inode)->i_disksize) {
 302                 /*
 303                  * We need to ensure that the inode is removed from the orphan
 304                  * list if it has been added prematurely, due to writeback of
 305                  * delalloc blocks.
 306                  */
 307                 if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
 308                         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 309
 310                         if (IS_ERR(handle)) {
 311                                 ext4_orphan_del(NULL, inode);
 312                                 return PTR_ERR(handle);
 313                         }
 314
 315                         ext4_orphan_del(handle, inode);
 316                         ext4_journal_stop(handle);
 317                 }
 318
 319                 return written;
 320         }
 321
 322         if (written < 0)
 323                 goto truncate;
 324
 325         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 326         if (IS_ERR(handle)) {
 327                 written = PTR_ERR(handle);
 328                 goto truncate;
 329         }
 330
 331         if (ext4_update_inode_size(inode, offset + written)) {
 332                 ret = ext4_mark_inode_dirty(handle, inode);
 333                 if (unlikely(ret)) {
 334                         written = ret;
 335                         ext4_journal_stop(handle);
 336                         goto truncate;
 337                 }
 338         }
 339
 340         /*
 341          * We may need to truncate allocated but not written blocks beyond EOF.
 342          */
 343         written_blk = ALIGN(offset + written, 1 << blkbits);
 344         end_blk = ALIGN(offset + count, 1 << blkbits);
 345         if (written_blk < end_blk && ext4_can_truncate(inode))
 346                 truncate = true;
 347
 348         /*
 349          * Remove the inode from the orphan list if it has been extended and
 350          * everything went OK.
 351          */
 352         if (!truncate && inode->i_nlink)
 353                 ext4_orphan_del(handle, inode);
 354         ext4_journal_stop(handle);
 355
 356         if (truncate) {
 357 truncate:
 358                 ext4_truncate_failed_write(inode);
 359                 /*
 360                  * If the truncate operation failed early, then the inode may
 361                  * still be on the orphan list. In that case, we need to try
 362                  * remove the inode from the in-memory linked list.
 363                  */
 364                 if (inode->i_nlink)
 365                         ext4_orphan_del(NULL, inode);
 366         }
 367
 368         return written;
 369 }
 370
 371 static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
 372                                  int error, unsigned int flags)
 373 {
 374         loff_t pos = iocb->ki_pos;
 375         struct inode *inode = file_inode(iocb->ki_filp);
 376
 377         if (error)
 378                 return error;
 379
 380         if (size && flags & IOMAP_DIO_UNWRITTEN) {
 381                 error = ext4_convert_unwritten_extents(NULL, inode, pos, size);
 382                 if (error < 0)
 383                         return error;
 384         }
 385         /*
 386          * If we are extending the file, we have to update i_size here before
 387          * page cache gets invalidated in iomap_dio_rw(). Otherwise racing
 388          * buffered reads could zero out too much from page cache pages. Update
 389          * of on-disk size will happen later in ext4_dio_write_iter() where
 390          * we have enough information to also perform orphan list handling etc.
 391          * Note that we perform all extending writes synchronously under
 392          * i_rwsem held exclusively so i_size update is safe here in that case.
 393          * If the write was not extending, we cannot see pos > i_size here
 394          * because operations reducing i_size like truncate wait for all
 395          * outstanding DIO before updating i_size.
 396          */
 397         pos += size;
 398         if (pos > i_size_read(inode))
 399                 i_size_write(inode, pos);
 400
 401         return 0;
 402 }
 403
 404 static const struct iomap_dio_ops ext4_dio_write_ops = {
 405         .end_io = ext4_dio_write_end_io,
 406 };
 407
 408 /*
 409  * The intention here is to start with shared lock acquired then see if any
 410  * condition requires an exclusive inode lock. If yes, then we restart the
 411  * whole operation by releasing the shared lock and acquiring exclusive lock.
 412  *
 413  * - For unaligned_io we never take shared lock as it may cause data corruption
 414  *   when two unaligned IO tries to modify the same block e.g. while zeroing.
 415  *
 416  * - For extending writes case we don't take the shared lock, since it requires
 417  *   updating inode i_disksize and/or orphan handling with exclusive lock.
 418  *
 419  * - shared locking will only be true mostly with overwrites. Otherwise we will
 420  *   switch to exclusive i_rwsem lock.
 421  */
 422 static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
 423                                      bool *ilock_shared, bool *extend)
 424 {
 425         struct file *file = iocb->ki_filp;
 426         struct inode *inode = file_inode(file);
 427         loff_t offset;
 428         size_t count;
 429         ssize_t ret;
 430
 431 restart:
 432         ret = ext4_generic_write_checks(iocb, from);
 433         if (ret <= 0)
 434                 goto out;
 435
 436         offset = iocb->ki_pos;
 437         count = ret;
 438         if (ext4_extending_io(inode, offset, count))
 439                 *extend = true;
 440         /*
 441          * Determine whether the IO operation will overwrite allocated
 442          * and initialized blocks.
 443          * We need exclusive i_rwsem for changing security info
 444          * in file_modified().
 445          */
 446         if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
 447              !ext4_overwrite_io(inode, offset, count))) {
 448                 if (iocb->ki_flags & IOCB_NOWAIT) {
 449                         ret = -EAGAIN;
 450                         goto out;
 451                 }
 452                 inode_unlock_shared(inode);
 453                 *ilock_shared = false;
 454                 inode_lock(inode);
 455                 goto restart;
 456         }
 457
 458         ret = file_modified(file);
 459         if (ret < 0)
 460                 goto out;
 461
 462         return count;
 463 out:
 464         if (*ilock_shared)
 465                 inode_unlock_shared(inode);
 466         else
 467                 inode_unlock(inode);
 468         return ret;
 469 }
 470
 471 static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 472 {
 473         ssize_t ret;
 474         handle_t *handle;
 475         struct inode *inode = file_inode(iocb->ki_filp);
 476         loff_t offset = iocb->ki_pos;
 477         size_t count = iov_iter_count(from);
 478         const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
 479         bool extend = false, unaligned_io = false;
 480         bool ilock_shared = true;
 481
 482         /*
 483          * We initially start with shared inode lock unless it is
 484          * unaligned IO which needs exclusive lock anyways.
 485          */
 486         if (ext4_unaligned_io(inode, from, offset)) {
 487                 unaligned_io = true;
 488                 ilock_shared = false;
 489         }
 490         /*
 491          * Quick check here without any i_rwsem lock to see if it is extending
 492          * IO. A more reliable check is done in ext4_dio_write_checks() with
 493          * proper locking in place.
 494          */
 495         if (offset + count > i_size_read(inode))
 496                 ilock_shared = false;
 497
 498         if (iocb->ki_flags & IOCB_NOWAIT) {
 499                 if (ilock_shared) {
 500                         if (!inode_trylock_shared(inode))
 501                                 return -EAGAIN;
 502                 } else {
 503                         if (!inode_trylock(inode))
 504                                 return -EAGAIN;
 505                 }
 506         } else {
 507                 if (ilock_shared)
 508                         inode_lock_shared(inode);
 509                 else
 510                         inode_lock(inode);
 511         }
 512
 513         /* Fallback to buffered I/O if the inode does not support direct I/O. */
 514         if (!ext4_dio_supported(inode)) {
 515                 if (ilock_shared)
 516                         inode_unlock_shared(inode);
 517                 else
 518                         inode_unlock(inode);
 519                 return ext4_buffered_write_iter(iocb, from);
 520         }
 521
 522         ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend);
 523         if (ret <= 0)
 524                 return ret;
 525
 526         /* if we're going to block and IOCB_NOWAIT is set, return -EAGAIN */
 527         if ((iocb->ki_flags & IOCB_NOWAIT) && (unaligned_io || extend)) {
 528                 ret = -EAGAIN;
 529                 goto out;
 530         }
 531
 532         offset = iocb->ki_pos;
 533         count = ret;
 534
 535         /*
 536          * Unaligned direct IO must be serialized among each other as zeroing
 537          * of partial blocks of two competing unaligned IOs can result in data
 538          * corruption.
 539          *
 540          * So we make sure we don't allow any unaligned IO in flight.
 541          * For IOs where we need not wait (like unaligned non-AIO DIO),
 542          * below inode_dio_wait() may anyway become a no-op, since we start
 543          * with exclusive lock.
 544          */
 545         if (unaligned_io)
 546                 inode_dio_wait(inode);
 547
 548         if (extend) {
 549                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 550                 if (IS_ERR(handle)) {
 551                         ret = PTR_ERR(handle);
 552                         goto out;
 553                 }
 554
 555                 ext4_fc_start_update(inode);
 556                 ret = ext4_orphan_add(handle, inode);
 557                 ext4_fc_stop_update(inode);
 558                 if (ret) {
 559                         ext4_journal_stop(handle);
 560                         goto out;
 561                 }
 562
 563                 ext4_journal_stop(handle);
 564         }
 565
 566         if (ilock_shared)
 567                 iomap_ops = &ext4_iomap_overwrite_ops;
 568         ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
 569                            (unaligned_io || extend) ? IOMAP_DIO_FORCE_WAIT : 0);
 570         if (ret == -ENOTBLK)
 571                 ret = 0;
 572
 573         if (extend)
 574                 ret = ext4_handle_inode_extension(inode, offset, ret, count);
 575
 576 out:
 577         if (ilock_shared)
 578                 inode_unlock_shared(inode);
 579         else
 580                 inode_unlock(inode);
 581
 582         if (ret >= 0 && iov_iter_count(from)) {
 583                 ssize_t err;
 584                 loff_t endbyte;
 585
 586                 offset = iocb->ki_pos;
 587                 err = ext4_buffered_write_iter(iocb, from);
 588                 if (err < 0)
 589                         return err;
 590
 591                 /*
 592                  * We need to ensure that the pages within the page cache for
 593                  * the range covered by this I/O are written to disk and
 594                  * invalidated. This is in attempt to preserve the expected
 595                  * direct I/O semantics in the case we fallback to buffered I/O
 596                  * to complete off the I/O request.
 597                  */
 598                 ret += err;
 599                 endbyte = offset + err - 1;
 600                 err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping,
 601                                                    offset, endbyte);
 602                 if (!err)
 603                         invalidate_mapping_pages(iocb->ki_filp->f_mapping,
 604                                                  offset >> PAGE_SHIFT,
 605                                                  endbyte >> PAGE_SHIFT);
 606         }
 607
 608         return ret;
 609 }
 610
 611 #ifdef CONFIG_FS_DAX
 612 static ssize_t
 613 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
 614 {
 615         ssize_t ret;
 616         size_t count;
 617         loff_t offset;
 618         handle_t *handle;
 619         bool extend = false;
 620         struct inode *inode = file_inode(iocb->ki_filp);
 621
 622         if (iocb->ki_flags & IOCB_NOWAIT) {
 623                 if (!inode_trylock(inode))
 624                         return -EAGAIN;
 625         } else {
 626                 inode_lock(inode);
 627         }
 628
 629         ret = ext4_write_checks(iocb, from);
 630         if (ret <= 0)
 631                 goto out;
 632
 633         offset = iocb->ki_pos;
 634         count = iov_iter_count(from);
 635
 636         if (offset + count > EXT4_I(inode)->i_disksize) {
 637                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 638                 if (IS_ERR(handle)) {
 639                         ret = PTR_ERR(handle);
 640                         goto out;
 641                 }
 642
 643                 ret = ext4_orphan_add(handle, inode);
 644                 if (ret) {
 645                         ext4_journal_stop(handle);
 646                         goto out;
 647                 }
 648
 649                 extend = true;
 650                 ext4_journal_stop(handle);
 651         }
 652
 653         ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
 654
 655         if (extend)
 656                 ret = ext4_handle_inode_extension(inode, offset, ret, count);
 657 out:
 658         inode_unlock(inode);
 659         if (ret > 0)
 660                 ret = generic_write_sync(iocb, ret);
 661         return ret;
 662 }
 663 #endif
 664
 665 static ssize_t
 666 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 667 {
 668         struct inode *inode = file_inode(iocb->ki_filp);
 669
 670         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 671                 return -EIO;
 672
 673 #ifdef CONFIG_FS_DAX
 674         if (IS_DAX(inode))
 675                 return ext4_dax_write_iter(iocb, from);
 676 #endif
 677         if (iocb->ki_flags & IOCB_DIRECT)
 678                 return ext4_dio_write_iter(iocb, from);
 679         else
 680                 return ext4_buffered_write_iter(iocb, from);
 681 }
 682
 683 #ifdef CONFIG_FS_DAX
 684 static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
 685                 enum page_entry_size pe_size)
 686 {
 687         int error = 0;
 688         vm_fault_t result;
 689         int retries = 0;
 690         handle_t *handle = NULL;
 691         struct inode *inode = file_inode(vmf->vma->vm_file);
 692         struct super_block *sb = inode->i_sb;
 693
 694         /*
 695          * We have to distinguish real writes from writes which will result in a
 696          * COW page; COW writes should *not* poke the journal (the file will not
 697          * be changed). Doing so would cause unintended failures when mounted
 698          * read-only.
 699          *
 700          * We check for VM_SHARED rather than vmf->cow_page since the latter is
 701          * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
 702          * other sizes, dax_iomap_fault will handle splitting / fallback so that
 703          * we eventually come back with a COW page.
 704          */
 705         bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
 706                 (vmf->vma->vm_flags & VM_SHARED);
 707         struct address_space *mapping = vmf->vma->vm_file->f_mapping;
 708         pfn_t pfn;
 709
 710         if (write) {
 711                 sb_start_pagefault(sb);
 712                 file_update_time(vmf->vma->vm_file);
 713                 filemap_invalidate_lock_shared(mapping);
 714 retry:
 715                 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
 716                                                EXT4_DATA_TRANS_BLOCKS(sb));
 717                 if (IS_ERR(handle)) {
 718                         filemap_invalidate_unlock_shared(mapping);
 719                         sb_end_pagefault(sb);
 720                         return VM_FAULT_SIGBUS;
 721                 }
 722         } else {
 723                 filemap_invalidate_lock_shared(mapping);
 724         }
 725         result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
 726         if (write) {
 727                 ext4_journal_stop(handle);
 728
 729                 if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
 730                     ext4_should_retry_alloc(sb, &retries))
 731                         goto retry;
 732                 /* Handling synchronous page fault? */
 733                 if (result & VM_FAULT_NEEDDSYNC)
 734                         result = dax_finish_sync_fault(vmf, pe_size, pfn);
 735                 filemap_invalidate_unlock_shared(mapping);
 736                 sb_end_pagefault(sb);
 737         } else {
 738                 filemap_invalidate_unlock_shared(mapping);
 739         }
 740
 741         return result;
 742 }
 743
 744 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
 745 {
 746         return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
 747 }
 748
 749 static const struct vm_operations_struct ext4_dax_vm_ops = {
 750         .fault          = ext4_dax_fault,
 751         .huge_fault     = ext4_dax_huge_fault,
 752         .page_mkwrite   = ext4_dax_fault,
 753         .pfn_mkwrite    = ext4_dax_fault,
 754 };
 755 #else
 756 #define ext4_dax_vm_ops ext4_file_vm_ops
 757 #endif
 758
 759 static const struct vm_operations_struct ext4_file_vm_ops = {
 760         .fault          = filemap_fault,
 761         .map_pages      = filemap_map_pages,
 762         .page_mkwrite   = ext4_page_mkwrite,
 763 };
 764
 765 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 766 {
 767         struct inode *inode = file->f_mapping->host;
 768         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 769         struct dax_device *dax_dev = sbi->s_daxdev;
 770
 771         if (unlikely(ext4_forced_shutdown(sbi)))
 772                 return -EIO;
 773
 774         /*
 775          * We don't support synchronous mappings for non-DAX files and
 776          * for DAX files if underneath dax_device is not synchronous.
 777          */
 778         if (!daxdev_mapping_supported(vma, dax_dev))
 779                 return -EOPNOTSUPP;
 780
 781         file_accessed(file);
 782         if (IS_DAX(file_inode(file))) {
 783                 vma->vm_ops = &ext4_dax_vm_ops;
 784                 vma->vm_flags |= VM_HUGEPAGE;
 785         } else {
 786                 vma->vm_ops = &ext4_file_vm_ops;
 787         }
 788         return 0;
 789 }
 790
 791 static int ext4_sample_last_mounted(struct super_block *sb,
 792                                     struct vfsmount *mnt)
 793 {
 794         struct ext4_sb_info *sbi = EXT4_SB(sb);
 795         struct path path;
 796         char buf[64], *cp;
 797         handle_t *handle;
 798         int err;
 799
 800         if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED)))
 801                 return 0;
 802
 803         if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
 804                 return 0;
 805
 806         ext4_set_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED);
 807         /*
 808          * Sample where the filesystem has been mounted and
 809          * store it in the superblock for sysadmin convenience
 810          * when trying to sort through large numbers of block
 811          * devices or filesystem images.
 812          */
 813         memset(buf, 0, sizeof(buf));
 814         path.mnt = mnt;
 815         path.dentry = mnt->mnt_root;
 816         cp = d_path(&path, buf, sizeof(buf));
 817         err = 0;
 818         if (IS_ERR(cp))
 819                 goto out;
 820
 821         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 822         err = PTR_ERR(handle);
 823         if (IS_ERR(handle))
 824                 goto out;
 825         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 826         err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh,
 827                                             EXT4_JTR_NONE);
 828         if (err)
 829                 goto out_journal;
 830         lock_buffer(sbi->s_sbh);
 831         strncpy(sbi->s_es->s_last_mounted, cp,
 832                 sizeof(sbi->s_es->s_last_mounted));
 833         ext4_superblock_csum_set(sb);
 834         unlock_buffer(sbi->s_sbh);
 835         ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
 836 out_journal:
 837         ext4_journal_stop(handle);
 838 out:
 839         sb_end_intwrite(sb);
 840         return err;
 841 }
 842
 843 static int ext4_file_open(struct inode *inode, struct file *filp)
 844 {
 845         int ret;
 846
 847         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 848                 return -EIO;
 849
 850         ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
 851         if (ret)
 852                 return ret;
 853
 854         ret = fscrypt_file_open(inode, filp);
 855         if (ret)
 856                 return ret;
 857
 858         ret = fsverity_file_open(inode, filp);
 859         if (ret)
 860                 return ret;
 861
 862         /*
 863          * Set up the jbd2_inode if we are opening the inode for
 864          * writing and the journal is present
 865          */
 866         if (filp->f_mode & FMODE_WRITE) {
 867                 ret = ext4_inode_attach_jinode(inode);
 868                 if (ret < 0)
 869                         return ret;
 870         }
 871
 872         filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
 873         return dquot_file_open(inode, filp);
 874 }
 875
 876 /*
 877  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 878  * by calling generic_file_llseek_size() with the appropriate maxbytes
 879  * value for each.
 880  */
 881 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 882 {
 883         struct inode *inode = file->f_mapping->host;
 884         loff_t maxbytes;
 885
 886         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 887                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 888         else
 889                 maxbytes = inode->i_sb->s_maxbytes;
 890
 891         switch (whence) {
 892         default:
 893                 return generic_file_llseek_size(file, offset, whence,
 894                                                 maxbytes, i_size_read(inode));
 895         case SEEK_HOLE:
 896                 inode_lock_shared(inode);
 897                 offset = iomap_seek_hole(inode, offset,
 898                                          &ext4_iomap_report_ops);
 899                 inode_unlock_shared(inode);
 900                 break;
 901         case SEEK_DATA:
 902                 inode_lock_shared(inode);
 903                 offset = iomap_seek_data(inode, offset,
 904                                          &ext4_iomap_report_ops);
 905                 inode_unlock_shared(inode);
 906                 break;
 907         }
 908
 909         if (offset < 0)
 910                 return offset;
 911         return vfs_setpos(file, offset, maxbytes);
 912 }
 913
 914 const struct file_operations ext4_file_operations = {
 915         .llseek         = ext4_llseek,
 916         .read_iter      = ext4_file_read_iter,
 917         .write_iter     = ext4_file_write_iter,
 918         .iopoll         = iomap_dio_iopoll,
 919         .unlocked_ioctl = ext4_ioctl,
 920 #ifdef CONFIG_COMPAT
 921         .compat_ioctl   = ext4_compat_ioctl,
 922 #endif
 923         .mmap           = ext4_file_mmap,
 924         .mmap_supported_flags = MAP_SYNC,
 925         .open           = ext4_file_open,
 926         .release        = ext4_release_file,
 927         .fsync          = ext4_sync_file,
 928         .get_unmapped_area = thp_get_unmapped_area,
 929         .splice_read    = generic_file_splice_read,
 930         .splice_write   = iter_file_splice_write,
 931         .fallocate      = ext4_fallocate,
 932 };
 933
 934 const struct inode_operations ext4_file_inode_operations = {
 935         .setattr        = ext4_setattr,
 936         .getattr        = ext4_file_getattr,
 937         .listxattr      = ext4_listxattr,
 938         .get_acl        = ext4_get_acl,
 939         .set_acl        = ext4_set_acl,
 940         .fiemap         = ext4_fiemap,
 941         .fileattr_get   = ext4_fileattr_get,
 942         .fileattr_set   = ext4_fileattr_set,
 943 };
 944