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 /*
  40  * Returns %true if the given DIO request should be attempted with DIO, or
  41  * %false if it should fall back to buffered I/O.
  42  *
  43  * DIO isn't well specified; when it's unsupported (either due to the request
  44  * being misaligned, or due to the file not supporting DIO at all), filesystems
  45  * either fall back to buffered I/O or return EINVAL.  For files that don't use
  46  * any special features like encryption or verity, ext4 has traditionally
  47  * returned EINVAL for misaligned DIO.  iomap_dio_rw() uses this convention too.
  48  * In this case, we should attempt the DIO, *not* fall back to buffered I/O.
  49  *
  50  * In contrast, in cases where DIO is unsupported due to ext4 features, ext4
  51  * traditionally falls back to buffered I/O.
  52  *
  53  * This function implements the traditional ext4 behavior in all these cases.
  54  */
  55 static bool ext4_should_use_dio(struct kiocb *iocb, struct iov_iter *iter)
  56 {
  57         struct inode *inode = file_inode(iocb->ki_filp);
  58         u32 dio_align = ext4_dio_alignment(inode);
  59
  60         if (dio_align == 0)
  61                 return false;
  62
  63         if (dio_align == 1)
  64                 return true;
  65
  66         return IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(iter), dio_align);
  67 }
  68
  69 static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
  70 {
  71         ssize_t ret;
  72         struct inode *inode = file_inode(iocb->ki_filp);
  73
  74         if (iocb->ki_flags & IOCB_NOWAIT) {
  75                 if (!inode_trylock_shared(inode))
  76                         return -EAGAIN;
  77         } else {
  78                 inode_lock_shared(inode);
  79         }
  80
  81         if (!ext4_should_use_dio(iocb, to)) {
  82                 inode_unlock_shared(inode);
  83                 /*
  84                  * Fallback to buffered I/O if the operation being performed on
  85                  * the inode is not supported by direct I/O. The IOCB_DIRECT
  86                  * flag needs to be cleared here in order to ensure that the
  87                  * direct I/O path within generic_file_read_iter() is not
  88                  * taken.
  89                  */
  90                 iocb->ki_flags &= ~IOCB_DIRECT;
  91                 return generic_file_read_iter(iocb, to);
  92         }
  93
  94         ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL, 0, NULL, 0);
  95         inode_unlock_shared(inode);
  96
  97         file_accessed(iocb->ki_filp);
  98         return ret;
  99 }
 100
 101 #ifdef CONFIG_FS_DAX
 102 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
 103 {
 104         struct inode *inode = file_inode(iocb->ki_filp);
 105         ssize_t ret;
 106
 107         if (iocb->ki_flags & IOCB_NOWAIT) {
 108                 if (!inode_trylock_shared(inode))
 109                         return -EAGAIN;
 110         } else {
 111                 inode_lock_shared(inode);
 112         }
 113         /*
 114          * Recheck under inode lock - at this point we are sure it cannot
 115          * change anymore
 116          */
 117         if (!IS_DAX(inode)) {
 118                 inode_unlock_shared(inode);
 119                 /* Fallback to buffered IO in case we cannot support DAX */
 120                 return generic_file_read_iter(iocb, to);
 121         }
 122         ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
 123         inode_unlock_shared(inode);
 124
 125         file_accessed(iocb->ki_filp);
 126         return ret;
 127 }
 128 #endif
 129
 130 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 131 {
 132         struct inode *inode = file_inode(iocb->ki_filp);
 133
 134         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 135                 return -EIO;
 136
 137         if (!iov_iter_count(to))
 138                 return 0; /* skip atime */
 139
 140 #ifdef CONFIG_FS_DAX
 141         if (IS_DAX(inode))
 142                 return ext4_dax_read_iter(iocb, to);
 143 #endif
 144         if (iocb->ki_flags & IOCB_DIRECT)
 145                 return ext4_dio_read_iter(iocb, to);
 146
 147         return generic_file_read_iter(iocb, to);
 148 }
 149
 150 /*
 151  * Called when an inode is released. Note that this is different
 152  * from ext4_file_open: open gets called at every open, but release
 153  * gets called only when /all/ the files are closed.
 154  */
 155 static int ext4_release_file(struct inode *inode, struct file *filp)
 156 {
 157         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
 158                 ext4_alloc_da_blocks(inode);
 159                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
 160         }
 161         /* if we are the last writer on the inode, drop the block reservation */
 162         if ((filp->f_mode & FMODE_WRITE) &&
 163                         (atomic_read(&inode->i_writecount) == 1) &&
 164                         !EXT4_I(inode)->i_reserved_data_blocks) {
 165                 down_write(&EXT4_I(inode)->i_data_sem);
 166                 ext4_discard_preallocations(inode, 0);
 167                 up_write(&EXT4_I(inode)->i_data_sem);
 168         }
 169         if (is_dx(inode) && filp->private_data)
 170                 ext4_htree_free_dir_info(filp->private_data);
 171
 172         return 0;
 173 }
 174
 175 /*
 176  * This tests whether the IO in question is block-aligned or not.
 177  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
 178  * are converted to written only after the IO is complete.  Until they are
 179  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
 180  * it needs to zero out portions of the start and/or end block.  If 2 AIO
 181  * threads are at work on the same unwritten block, they must be synchronized
 182  * or one thread will zero the other's data, causing corruption.
 183  */
 184 static bool
 185 ext4_unaligned_io(struct inode *inode, struct iov_iter *from, loff_t pos)
 186 {
 187         struct super_block *sb = inode->i_sb;
 188         unsigned long blockmask = sb->s_blocksize - 1;
 189
 190         if ((pos | iov_iter_alignment(from)) & blockmask)
 191                 return true;
 192
 193         return false;
 194 }
 195
 196 static bool
 197 ext4_extending_io(struct inode *inode, loff_t offset, size_t len)
 198 {
 199         if (offset + len > i_size_read(inode) ||
 200             offset + len > EXT4_I(inode)->i_disksize)
 201                 return true;
 202         return false;
 203 }
 204
 205 /* Is IO overwriting allocated and initialized blocks? */
 206 static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
 207 {
 208         struct ext4_map_blocks map;
 209         unsigned int blkbits = inode->i_blkbits;
 210         int err, blklen;
 211
 212         if (pos + len > i_size_read(inode))
 213                 return false;
 214
 215         map.m_lblk = pos >> blkbits;
 216         map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
 217         blklen = map.m_len;
 218
 219         err = ext4_map_blocks(NULL, inode, &map, 0);
 220         /*
 221          * 'err==len' means that all of the blocks have been preallocated,
 222          * regardless of whether they have been initialized or not. To exclude
 223          * unwritten extents, we need to check m_flags.
 224          */
 225         return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
 226 }
 227
 228 static ssize_t ext4_generic_write_checks(struct kiocb *iocb,
 229                                          struct iov_iter *from)
 230 {
 231         struct inode *inode = file_inode(iocb->ki_filp);
 232         ssize_t ret;
 233
 234         if (unlikely(IS_IMMUTABLE(inode)))
 235                 return -EPERM;
 236
 237         ret = generic_write_checks(iocb, from);
 238         if (ret <= 0)
 239                 return ret;
 240
 241         /*
 242          * If we have encountered a bitmap-format file, the size limit
 243          * is smaller than s_maxbytes, which is for extent-mapped files.
 244          */
 245         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 246                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 247
 248                 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
 249                         return -EFBIG;
 250                 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
 251         }
 252
 253         return iov_iter_count(from);
 254 }
 255
 256 static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
 257 {
 258         ssize_t ret, count;
 259
 260         count = ext4_generic_write_checks(iocb, from);
 261         if (count <= 0)
 262                 return count;
 263
 264         ret = file_modified(iocb->ki_filp);
 265         if (ret)
 266                 return ret;
 267         return count;
 268 }
 269
 270 static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
 271                                         struct iov_iter *from)
 272 {
 273         ssize_t ret;
 274         struct inode *inode = file_inode(iocb->ki_filp);
 275
 276         if (iocb->ki_flags & IOCB_NOWAIT)
 277                 return -EOPNOTSUPP;
 278
 279         inode_lock(inode);
 280         ret = ext4_write_checks(iocb, from);
 281         if (ret <= 0)
 282                 goto out;
 283
 284         current->backing_dev_info = inode_to_bdi(inode);
 285         ret = generic_perform_write(iocb, from);
 286         current->backing_dev_info = NULL;
 287
 288 out:
 289         inode_unlock(inode);
 290         if (likely(ret > 0)) {
 291                 iocb->ki_pos += ret;
 292                 ret = generic_write_sync(iocb, ret);
 293         }
 294
 295         return ret;
 296 }
 297
 298 static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
 299                                            ssize_t count)
 300 {
 301         handle_t *handle;
 302
 303         lockdep_assert_held_write(&inode->i_rwsem);
 304         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 305         if (IS_ERR(handle))
 306                 return PTR_ERR(handle);
 307
 308         if (ext4_update_inode_size(inode, offset + count)) {
 309                 int ret = ext4_mark_inode_dirty(handle, inode);
 310                 if (unlikely(ret)) {
 311                         ext4_journal_stop(handle);
 312                         return ret;
 313                 }
 314         }
 315
 316         if (inode->i_nlink)
 317                 ext4_orphan_del(handle, inode);
 318         ext4_journal_stop(handle);
 319
 320         return count;
 321 }
 322
 323 /*
 324  * Clean up the inode after DIO or DAX extending write has completed and the
 325  * inode size has been updated using ext4_handle_inode_extension().
 326  */
 327 static void ext4_inode_extension_cleanup(struct inode *inode, ssize_t count)
 328 {
 329         lockdep_assert_held_write(&inode->i_rwsem);
 330         if (count < 0) {
 331                 ext4_truncate_failed_write(inode);
 332                 /*
 333                  * If the truncate operation failed early, then the inode may
 334                  * still be on the orphan list. In that case, we need to try
 335                  * remove the inode from the in-memory linked list.
 336                  */
 337                 if (inode->i_nlink)
 338                         ext4_orphan_del(NULL, inode);
 339                 return;
 340         }
 341         /*
 342          * If i_disksize got extended either due to writeback of delalloc
 343          * blocks or extending truncate while the DIO was running we could fail
 344          * to cleanup the orphan list in ext4_handle_inode_extension(). Do it
 345          * now.
 346          */
 347         if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
 348                 handle_t *handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 349
 350                 if (IS_ERR(handle)) {
 351                         /*
 352                          * The write has successfully completed. Not much to
 353                          * do with the error here so just cleanup the orphan
 354                          * list and hope for the best.
 355                          */
 356                         ext4_orphan_del(NULL, inode);
 357                         return;
 358                 }
 359                 ext4_orphan_del(handle, inode);
 360                 ext4_journal_stop(handle);
 361         }
 362 }
 363
 364 static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
 365                                  int error, unsigned int flags)
 366 {
 367         loff_t pos = iocb->ki_pos;
 368         struct inode *inode = file_inode(iocb->ki_filp);
 369
 370         if (!error && size && flags & IOMAP_DIO_UNWRITTEN)
 371                 error = ext4_convert_unwritten_extents(NULL, inode, pos, size);
 372         if (error)
 373                 return error;
 374         /*
 375          * Note that EXT4_I(inode)->i_disksize can get extended up to
 376          * inode->i_size while the I/O was running due to writeback of delalloc
 377          * blocks. But the code in ext4_iomap_alloc() is careful to use
 378          * zeroed/unwritten extents if this is possible; thus we won't leave
 379          * uninitialized blocks in a file even if we didn't succeed in writing
 380          * as much as we intended. Also we can race with truncate or write
 381          * expanding the file so we have to be a bit careful here.
 382          */
 383         if (pos + size <= READ_ONCE(EXT4_I(inode)->i_disksize) &&
 384             pos + size <= i_size_read(inode))
 385                 return size;
 386         return ext4_handle_inode_extension(inode, pos, size);
 387 }
 388
 389 static const struct iomap_dio_ops ext4_dio_write_ops = {
 390         .end_io = ext4_dio_write_end_io,
 391 };
 392
 393 /*
 394  * The intention here is to start with shared lock acquired then see if any
 395  * condition requires an exclusive inode lock. If yes, then we restart the
 396  * whole operation by releasing the shared lock and acquiring exclusive lock.
 397  *
 398  * - For unaligned_io we never take shared lock as it may cause data corruption
 399  *   when two unaligned IO tries to modify the same block e.g. while zeroing.
 400  *
 401  * - For extending writes case we don't take the shared lock, since it requires
 402  *   updating inode i_disksize and/or orphan handling with exclusive lock.
 403  *
 404  * - shared locking will only be true mostly with overwrites. Otherwise we will
 405  *   switch to exclusive i_rwsem lock.
 406  */
 407 static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
 408                                      bool *ilock_shared, bool *extend)
 409 {
 410         struct file *file = iocb->ki_filp;
 411         struct inode *inode = file_inode(file);
 412         loff_t offset;
 413         size_t count;
 414         ssize_t ret;
 415
 416 restart:
 417         ret = ext4_generic_write_checks(iocb, from);
 418         if (ret <= 0)
 419                 goto out;
 420
 421         offset = iocb->ki_pos;
 422         count = ret;
 423         if (ext4_extending_io(inode, offset, count))
 424                 *extend = true;
 425         /*
 426          * Determine whether the IO operation will overwrite allocated
 427          * and initialized blocks.
 428          * We need exclusive i_rwsem for changing security info
 429          * in file_modified().
 430          */
 431         if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
 432              !ext4_overwrite_io(inode, offset, count))) {
 433                 if (iocb->ki_flags & IOCB_NOWAIT) {
 434                         ret = -EAGAIN;
 435                         goto out;
 436                 }
 437                 inode_unlock_shared(inode);
 438                 *ilock_shared = false;
 439                 inode_lock(inode);
 440                 goto restart;
 441         }
 442
 443         ret = file_modified(file);
 444         if (ret < 0)
 445                 goto out;
 446
 447         return count;
 448 out:
 449         if (*ilock_shared)
 450                 inode_unlock_shared(inode);
 451         else
 452                 inode_unlock(inode);
 453         return ret;
 454 }
 455
 456 static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 457 {
 458         ssize_t ret;
 459         handle_t *handle;
 460         struct inode *inode = file_inode(iocb->ki_filp);
 461         loff_t offset = iocb->ki_pos;
 462         size_t count = iov_iter_count(from);
 463         const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
 464         bool extend = false, unaligned_io = false;
 465         bool ilock_shared = true;
 466
 467         /*
 468          * We initially start with shared inode lock unless it is
 469          * unaligned IO which needs exclusive lock anyways.
 470          */
 471         if (ext4_unaligned_io(inode, from, offset)) {
 472                 unaligned_io = true;
 473                 ilock_shared = false;
 474         }
 475         /*
 476          * Quick check here without any i_rwsem lock to see if it is extending
 477          * IO. A more reliable check is done in ext4_dio_write_checks() with
 478          * proper locking in place.
 479          */
 480         if (offset + count > i_size_read(inode))
 481                 ilock_shared = false;
 482
 483         if (iocb->ki_flags & IOCB_NOWAIT) {
 484                 if (ilock_shared) {
 485                         if (!inode_trylock_shared(inode))
 486                                 return -EAGAIN;
 487                 } else {
 488                         if (!inode_trylock(inode))
 489                                 return -EAGAIN;
 490                 }
 491         } else {
 492                 if (ilock_shared)
 493                         inode_lock_shared(inode);
 494                 else
 495                         inode_lock(inode);
 496         }
 497
 498         /* Fallback to buffered I/O if the inode does not support direct I/O. */
 499         if (!ext4_should_use_dio(iocb, from)) {
 500                 if (ilock_shared)
 501                         inode_unlock_shared(inode);
 502                 else
 503                         inode_unlock(inode);
 504                 return ext4_buffered_write_iter(iocb, from);
 505         }
 506
 507         ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend);
 508         if (ret <= 0)
 509                 return ret;
 510
 511         /* if we're going to block and IOCB_NOWAIT is set, return -EAGAIN */
 512         if ((iocb->ki_flags & IOCB_NOWAIT) && (unaligned_io || extend)) {
 513                 ret = -EAGAIN;
 514                 goto out;
 515         }
 516         /*
 517          * Make sure inline data cannot be created anymore since we are going
 518          * to allocate blocks for DIO. We know the inode does not have any
 519          * inline data now because ext4_dio_supported() checked for that.
 520          */
 521         ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
 522
 523         offset = iocb->ki_pos;
 524         count = ret;
 525
 526         /*
 527          * Unaligned direct IO must be serialized among each other as zeroing
 528          * of partial blocks of two competing unaligned IOs can result in data
 529          * corruption.
 530          *
 531          * So we make sure we don't allow any unaligned IO in flight.
 532          * For IOs where we need not wait (like unaligned non-AIO DIO),
 533          * below inode_dio_wait() may anyway become a no-op, since we start
 534          * with exclusive lock.
 535          */
 536         if (unaligned_io)
 537                 inode_dio_wait(inode);
 538
 539         if (extend) {
 540                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 541                 if (IS_ERR(handle)) {
 542                         ret = PTR_ERR(handle);
 543                         goto out;
 544                 }
 545
 546                 ret = ext4_orphan_add(handle, inode);
 547                 if (ret) {
 548                         ext4_journal_stop(handle);
 549                         goto out;
 550                 }
 551
 552                 ext4_journal_stop(handle);
 553         }
 554
 555         if (ilock_shared)
 556                 iomap_ops = &ext4_iomap_overwrite_ops;
 557         ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
 558                            (unaligned_io || extend) ? IOMAP_DIO_FORCE_WAIT : 0,
 559                            NULL, 0);
 560         if (ret == -ENOTBLK)
 561                 ret = 0;
 562         if (extend) {
 563                 /*
 564                  * We always perform extending DIO write synchronously so by
 565                  * now the IO is completed and ext4_handle_inode_extension()
 566                  * was called. Cleanup the inode in case of error or race with
 567                  * writeback of delalloc blocks.
 568                  */
 569                 WARN_ON_ONCE(ret == -EIOCBQUEUED);
 570                 ext4_inode_extension_cleanup(inode, ret);
 571         }
 572
 573 out:
 574         if (ilock_shared)
 575                 inode_unlock_shared(inode);
 576         else
 577                 inode_unlock(inode);
 578
 579         if (ret >= 0 && iov_iter_count(from)) {
 580                 ssize_t err;
 581                 loff_t endbyte;
 582
 583                 offset = iocb->ki_pos;
 584                 err = ext4_buffered_write_iter(iocb, from);
 585                 if (err < 0)
 586                         return err;
 587
 588                 /*
 589                  * We need to ensure that the pages within the page cache for
 590                  * the range covered by this I/O are written to disk and
 591                  * invalidated. This is in attempt to preserve the expected
 592                  * direct I/O semantics in the case we fallback to buffered I/O
 593                  * to complete off the I/O request.
 594                  */
 595                 ret += err;
 596                 endbyte = offset + err - 1;
 597                 err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping,
 598                                                    offset, endbyte);
 599                 if (!err)
 600                         invalidate_mapping_pages(iocb->ki_filp->f_mapping,
 601                                                  offset >> PAGE_SHIFT,
 602                                                  endbyte >> PAGE_SHIFT);
 603         }
 604
 605         return ret;
 606 }
 607
 608 #ifdef CONFIG_FS_DAX
 609 static ssize_t
 610 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
 611 {
 612         ssize_t ret;
 613         size_t count;
 614         loff_t offset;
 615         handle_t *handle;
 616         bool extend = false;
 617         struct inode *inode = file_inode(iocb->ki_filp);
 618
 619         if (iocb->ki_flags & IOCB_NOWAIT) {
 620                 if (!inode_trylock(inode))
 621                         return -EAGAIN;
 622         } else {
 623                 inode_lock(inode);
 624         }
 625
 626         ret = ext4_write_checks(iocb, from);
 627         if (ret <= 0)
 628                 goto out;
 629
 630         offset = iocb->ki_pos;
 631         count = iov_iter_count(from);
 632
 633         if (offset + count > EXT4_I(inode)->i_disksize) {
 634                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 635                 if (IS_ERR(handle)) {
 636                         ret = PTR_ERR(handle);
 637                         goto out;
 638                 }
 639
 640                 ret = ext4_orphan_add(handle, inode);
 641                 if (ret) {
 642                         ext4_journal_stop(handle);
 643                         goto out;
 644                 }
 645
 646                 extend = true;
 647                 ext4_journal_stop(handle);
 648         }
 649
 650         ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
 651
 652         if (extend) {
 653                 ret = ext4_handle_inode_extension(inode, offset, ret);
 654                 ext4_inode_extension_cleanup(inode, ret);
 655         }
 656 out:
 657         inode_unlock(inode);
 658         if (ret > 0)
 659                 ret = generic_write_sync(iocb, ret);
 660         return ret;
 661 }
 662 #endif
 663
 664 static ssize_t
 665 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 666 {
 667         struct inode *inode = file_inode(iocb->ki_filp);
 668
 669         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 670                 return -EIO;
 671
 672 #ifdef CONFIG_FS_DAX
 673         if (IS_DAX(inode))
 674                 return ext4_dax_write_iter(iocb, from);
 675 #endif
 676         if (iocb->ki_flags & IOCB_DIRECT)
 677                 return ext4_dio_write_iter(iocb, from);
 678         else
 679                 return ext4_buffered_write_iter(iocb, from);
 680 }
 681
 682 #ifdef CONFIG_FS_DAX
 683 static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
 684                 enum page_entry_size pe_size)
 685 {
 686         int error = 0;
 687         vm_fault_t result;
 688         int retries = 0;
 689         handle_t *handle = NULL;
 690         struct inode *inode = file_inode(vmf->vma->vm_file);
 691         struct super_block *sb = inode->i_sb;
 692
 693         /*
 694          * We have to distinguish real writes from writes which will result in a
 695          * COW page; COW writes should *not* poke the journal (the file will not
 696          * be changed). Doing so would cause unintended failures when mounted
 697          * read-only.
 698          *
 699          * We check for VM_SHARED rather than vmf->cow_page since the latter is
 700          * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
 701          * other sizes, dax_iomap_fault will handle splitting / fallback so that
 702          * we eventually come back with a COW page.
 703          */
 704         bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
 705                 (vmf->vma->vm_flags & VM_SHARED);
 706         struct address_space *mapping = vmf->vma->vm_file->f_mapping;
 707         pfn_t pfn;
 708
 709         if (write) {
 710                 sb_start_pagefault(sb);
 711                 file_update_time(vmf->vma->vm_file);
 712                 filemap_invalidate_lock_shared(mapping);
 713 retry:
 714                 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
 715                                                EXT4_DATA_TRANS_BLOCKS(sb));
 716                 if (IS_ERR(handle)) {
 717                         filemap_invalidate_unlock_shared(mapping);
 718                         sb_end_pagefault(sb);
 719                         return VM_FAULT_SIGBUS;
 720                 }
 721         } else {
 722                 filemap_invalidate_lock_shared(mapping);
 723         }
 724         result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
 725         if (write) {
 726                 ext4_journal_stop(handle);
 727
 728                 if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
 729                     ext4_should_retry_alloc(sb, &retries))
 730                         goto retry;
 731                 /* Handling synchronous page fault? */
 732                 if (result & VM_FAULT_NEEDDSYNC)
 733                         result = dax_finish_sync_fault(vmf, pe_size, pfn);
 734                 filemap_invalidate_unlock_shared(mapping);
 735                 sb_end_pagefault(sb);
 736         } else {
 737                 filemap_invalidate_unlock_shared(mapping);
 738         }
 739
 740         return result;
 741 }
 742
 743 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
 744 {
 745         return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
 746 }
 747
 748 static const struct vm_operations_struct ext4_dax_vm_ops = {
 749         .fault          = ext4_dax_fault,
 750         .huge_fault     = ext4_dax_huge_fault,
 751         .page_mkwrite   = ext4_dax_fault,
 752         .pfn_mkwrite    = ext4_dax_fault,
 753 };
 754 #else
 755 #define ext4_dax_vm_ops ext4_file_vm_ops
 756 #endif
 757
 758 static const struct vm_operations_struct ext4_file_vm_ops = {
 759         .fault          = filemap_fault,
 760         .map_pages      = filemap_map_pages,
 761         .page_mkwrite   = ext4_page_mkwrite,
 762 };
 763
 764 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 765 {
 766         struct inode *inode = file->f_mapping->host;
 767         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 768         struct dax_device *dax_dev = sbi->s_daxdev;
 769
 770         if (unlikely(ext4_forced_shutdown(sbi)))
 771                 return -EIO;
 772
 773         /*
 774          * We don't support synchronous mappings for non-DAX files and
 775          * for DAX files if underneath dax_device is not synchronous.
 776          */
 777         if (!daxdev_mapping_supported(vma, dax_dev))
 778                 return -EOPNOTSUPP;
 779
 780         file_accessed(file);
 781         if (IS_DAX(file_inode(file))) {
 782                 vma->vm_ops = &ext4_dax_vm_ops;
 783                 vma->vm_flags |= VM_HUGEPAGE;
 784         } else {
 785                 vma->vm_ops = &ext4_file_vm_ops;
 786         }
 787         return 0;
 788 }
 789
 790 static int ext4_sample_last_mounted(struct super_block *sb,
 791                                     struct vfsmount *mnt)
 792 {
 793         struct ext4_sb_info *sbi = EXT4_SB(sb);
 794         struct path path;
 795         char buf[64], *cp;
 796         handle_t *handle;
 797         int err;
 798
 799         if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED)))
 800                 return 0;
 801
 802         if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
 803                 return 0;
 804
 805         ext4_set_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED);
 806         /*
 807          * Sample where the filesystem has been mounted and
 808          * store it in the superblock for sysadmin convenience
 809          * when trying to sort through large numbers of block
 810          * devices or filesystem images.
 811          */
 812         memset(buf, 0, sizeof(buf));
 813         path.mnt = mnt;
 814         path.dentry = mnt->mnt_root;
 815         cp = d_path(&path, buf, sizeof(buf));
 816         err = 0;
 817         if (IS_ERR(cp))
 818                 goto out;
 819
 820         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 821         err = PTR_ERR(handle);
 822         if (IS_ERR(handle))
 823                 goto out;
 824         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 825         err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh,
 826                                             EXT4_JTR_NONE);
 827         if (err)
 828                 goto out_journal;
 829         lock_buffer(sbi->s_sbh);
 830         strncpy(sbi->s_es->s_last_mounted, cp,
 831                 sizeof(sbi->s_es->s_last_mounted));
 832         ext4_superblock_csum_set(sb);
 833         unlock_buffer(sbi->s_sbh);
 834         ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
 835 out_journal:
 836         ext4_journal_stop(handle);
 837 out:
 838         sb_end_intwrite(sb);
 839         return err;
 840 }
 841
 842 static int ext4_file_open(struct inode *inode, struct file *filp)
 843 {
 844         int ret;
 845
 846         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 847                 return -EIO;
 848
 849         ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
 850         if (ret)
 851                 return ret;
 852
 853         ret = fscrypt_file_open(inode, filp);
 854         if (ret)
 855                 return ret;
 856
 857         ret = fsverity_file_open(inode, filp);
 858         if (ret)
 859                 return ret;
 860
 861         /*
 862          * Set up the jbd2_inode if we are opening the inode for
 863          * writing and the journal is present
 864          */
 865         if (filp->f_mode & FMODE_WRITE) {
 866                 ret = ext4_inode_attach_jinode(inode);
 867                 if (ret < 0)
 868                         return ret;
 869         }
 870
 871         filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
 872         return dquot_file_open(inode, filp);
 873 }
 874
 875 /*
 876  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 877  * by calling generic_file_llseek_size() with the appropriate maxbytes
 878  * value for each.
 879  */
 880 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 881 {
 882         struct inode *inode = file->f_mapping->host;
 883         loff_t maxbytes;
 884
 885         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 886                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 887         else
 888                 maxbytes = inode->i_sb->s_maxbytes;
 889
 890         switch (whence) {
 891         default:
 892                 return generic_file_llseek_size(file, offset, whence,
 893                                                 maxbytes, i_size_read(inode));
 894         case SEEK_HOLE:
 895                 inode_lock_shared(inode);
 896                 offset = iomap_seek_hole(inode, offset,
 897                                          &ext4_iomap_report_ops);
 898                 inode_unlock_shared(inode);
 899                 break;
 900         case SEEK_DATA:
 901                 inode_lock_shared(inode);
 902                 offset = iomap_seek_data(inode, offset,
 903                                          &ext4_iomap_report_ops);
 904                 inode_unlock_shared(inode);
 905                 break;
 906         }
 907
 908         if (offset < 0)
 909                 return offset;
 910         return vfs_setpos(file, offset, maxbytes);
 911 }
 912
 913 const struct file_operations ext4_file_operations = {
 914         .llseek         = ext4_llseek,
 915         .read_iter      = ext4_file_read_iter,
 916         .write_iter     = ext4_file_write_iter,
 917         .iopoll         = iocb_bio_iopoll,
 918         .unlocked_ioctl = ext4_ioctl,
 919 #ifdef CONFIG_COMPAT
 920         .compat_ioctl   = ext4_compat_ioctl,
 921 #endif
 922         .mmap           = ext4_file_mmap,
 923         .mmap_supported_flags = MAP_SYNC,
 924         .open           = ext4_file_open,
 925         .release        = ext4_release_file,
 926         .fsync          = ext4_sync_file,
 927         .get_unmapped_area = thp_get_unmapped_area,
 928         .splice_read    = generic_file_splice_read,
 929         .splice_write   = iter_file_splice_write,
 930         .fallocate      = ext4_fallocate,
 931 };
 932
 933 const struct inode_operations ext4_file_inode_operations = {
 934         .setattr        = ext4_setattr,
 935         .getattr        = ext4_file_getattr,
 936         .listxattr      = ext4_listxattr,
 937         .get_acl        = ext4_get_acl,
 938         .set_acl        = ext4_set_acl,
 939         .fiemap         = ext4_fiemap,
 940         .fileattr_get   = ext4_fileattr_get,
 941         .fileattr_set   = ext4_fileattr_set,
 942 };
 943