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 ([email protected])
   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  *      ([email protected])
  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,
  78                            is_sync_kiocb(iocb));
  79         inode_unlock_shared(inode);
  80
  81         file_accessed(iocb->ki_filp);
  82         return ret;
  83 }
  84
  85 #ifdef CONFIG_FS_DAX
  86 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
  87 {
  88         struct inode *inode = file_inode(iocb->ki_filp);
  89         ssize_t ret;
  90
  91         if (iocb->ki_flags & IOCB_NOWAIT) {
  92                 if (!inode_trylock_shared(inode))
  93                         return -EAGAIN;
  94         } else {
  95                 inode_lock_shared(inode);
  96         }
  97         /*
  98          * Recheck under inode lock - at this point we are sure it cannot
  99          * change anymore
 100          */
 101         if (!IS_DAX(inode)) {
 102                 inode_unlock_shared(inode);
 103                 /* Fallback to buffered IO in case we cannot support DAX */
 104                 return generic_file_read_iter(iocb, to);
 105         }
 106         ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
 107         inode_unlock_shared(inode);
 108
 109         file_accessed(iocb->ki_filp);
 110         return ret;
 111 }
 112 #endif
 113
 114 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 115 {
 116         struct inode *inode = file_inode(iocb->ki_filp);
 117
 118         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 119                 return -EIO;
 120
 121         if (!iov_iter_count(to))
 122                 return 0; /* skip atime */
 123
 124 #ifdef CONFIG_FS_DAX
 125         if (IS_DAX(inode))
 126                 return ext4_dax_read_iter(iocb, to);
 127 #endif
 128         if (iocb->ki_flags & IOCB_DIRECT)
 129                 return ext4_dio_read_iter(iocb, to);
 130
 131         return generic_file_read_iter(iocb, to);
 132 }
 133
 134 /*
 135  * Called when an inode is released. Note that this is different
 136  * from ext4_file_open: open gets called at every open, but release
 137  * gets called only when /all/ the files are closed.
 138  */
 139 static int ext4_release_file(struct inode *inode, struct file *filp)
 140 {
 141         if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
 142                 ext4_alloc_da_blocks(inode);
 143                 ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
 144         }
 145         /* if we are the last writer on the inode, drop the block reservation */
 146         if ((filp->f_mode & FMODE_WRITE) &&
 147                         (atomic_read(&inode->i_writecount) == 1) &&
 148                         !EXT4_I(inode)->i_reserved_data_blocks)
 149         {
 150                 down_write(&EXT4_I(inode)->i_data_sem);
 151                 ext4_discard_preallocations(inode);
 152                 up_write(&EXT4_I(inode)->i_data_sem);
 153         }
 154         if (is_dx(inode) && filp->private_data)
 155                 ext4_htree_free_dir_info(filp->private_data);
 156
 157         return 0;
 158 }
 159
 160 /*
 161  * This tests whether the IO in question is block-aligned or not.
 162  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
 163  * are converted to written only after the IO is complete.  Until they are
 164  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
 165  * it needs to zero out portions of the start and/or end block.  If 2 AIO
 166  * threads are at work on the same unwritten block, they must be synchronized
 167  * or one thread will zero the other's data, causing corruption.
 168  */
 169 static bool
 170 ext4_unaligned_io(struct inode *inode, struct iov_iter *from, loff_t pos)
 171 {
 172         struct super_block *sb = inode->i_sb;
 173         unsigned long blockmask = sb->s_blocksize - 1;
 174
 175         if ((pos | iov_iter_alignment(from)) & blockmask)
 176                 return true;
 177
 178         return false;
 179 }
 180
 181 static bool
 182 ext4_extending_io(struct inode *inode, loff_t offset, size_t len)
 183 {
 184         if (offset + len > i_size_read(inode) ||
 185             offset + len > EXT4_I(inode)->i_disksize)
 186                 return true;
 187         return false;
 188 }
 189
 190 /* Is IO overwriting allocated and initialized blocks? */
 191 static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
 192 {
 193         struct ext4_map_blocks map;
 194         unsigned int blkbits = inode->i_blkbits;
 195         int err, blklen;
 196
 197         if (pos + len > i_size_read(inode))
 198                 return false;
 199
 200         map.m_lblk = pos >> blkbits;
 201         map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
 202         blklen = map.m_len;
 203
 204         err = ext4_map_blocks(NULL, inode, &map, 0);
 205         /*
 206          * 'err==len' means that all of the blocks have been preallocated,
 207          * regardless of whether they have been initialized or not. To exclude
 208          * unwritten extents, we need to check m_flags.
 209          */
 210         return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
 211 }
 212
 213 static ssize_t ext4_generic_write_checks(struct kiocb *iocb,
 214                                          struct iov_iter *from)
 215 {
 216         struct inode *inode = file_inode(iocb->ki_filp);
 217         ssize_t ret;
 218
 219         if (unlikely(IS_IMMUTABLE(inode)))
 220                 return -EPERM;
 221
 222         ret = generic_write_checks(iocb, from);
 223         if (ret <= 0)
 224                 return ret;
 225
 226         /*
 227          * If we have encountered a bitmap-format file, the size limit
 228          * is smaller than s_maxbytes, which is for extent-mapped files.
 229          */
 230         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
 231                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 232
 233                 if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
 234                         return -EFBIG;
 235                 iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
 236         }
 237
 238         return iov_iter_count(from);
 239 }
 240
 241 static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
 242 {
 243         ssize_t ret, count;
 244
 245         count = ext4_generic_write_checks(iocb, from);
 246         if (count <= 0)
 247                 return count;
 248
 249         ret = file_modified(iocb->ki_filp);
 250         if (ret)
 251                 return ret;
 252         return count;
 253 }
 254
 255 static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
 256                                         struct iov_iter *from)
 257 {
 258         ssize_t ret;
 259         struct inode *inode = file_inode(iocb->ki_filp);
 260
 261         if (iocb->ki_flags & IOCB_NOWAIT)
 262                 return -EOPNOTSUPP;
 263
 264         inode_lock(inode);
 265         ret = ext4_write_checks(iocb, from);
 266         if (ret <= 0)
 267                 goto out;
 268
 269         current->backing_dev_info = inode_to_bdi(inode);
 270         ret = generic_perform_write(iocb->ki_filp, from, iocb->ki_pos);
 271         current->backing_dev_info = NULL;
 272
 273 out:
 274         inode_unlock(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
 291         /*
 292          * Note that EXT4_I(inode)->i_disksize can get extended up to
 293          * inode->i_size while the I/O was running due to writeback of delalloc
 294          * blocks. But, the code in ext4_iomap_alloc() is careful to use
 295          * zeroed/unwritten extents if this is possible; thus we won't leave
 296          * uninitialized blocks in a file even if we didn't succeed in writing
 297          * as much as we intended.
 298          */
 299         WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize);
 300         if (offset + count <= EXT4_I(inode)->i_disksize) {
 301                 /*
 302                  * We need to ensure that the inode is removed from the orphan
 303                  * list if it has been added prematurely, due to writeback of
 304                  * delalloc blocks.
 305                  */
 306                 if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
 307                         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 308
 309                         if (IS_ERR(handle)) {
 310                                 ext4_orphan_del(NULL, inode);
 311                                 return PTR_ERR(handle);
 312                         }
 313
 314                         ext4_orphan_del(handle, inode);
 315                         ext4_journal_stop(handle);
 316                 }
 317
 318                 return written;
 319         }
 320
 321         if (written < 0)
 322                 goto truncate;
 323
 324         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 325         if (IS_ERR(handle)) {
 326                 written = PTR_ERR(handle);
 327                 goto truncate;
 328         }
 329
 330         if (ext4_update_inode_size(inode, offset + written))
 331                 ext4_mark_inode_dirty(handle, inode);
 332
 333         /*
 334          * We may need to truncate allocated but not written blocks beyond EOF.
 335          */
 336         written_blk = ALIGN(offset + written, 1 << blkbits);
 337         end_blk = ALIGN(offset + count, 1 << blkbits);
 338         if (written_blk < end_blk && ext4_can_truncate(inode))
 339                 truncate = true;
 340
 341         /*
 342          * Remove the inode from the orphan list if it has been extended and
 343          * everything went OK.
 344          */
 345         if (!truncate && inode->i_nlink)
 346                 ext4_orphan_del(handle, inode);
 347         ext4_journal_stop(handle);
 348
 349         if (truncate) {
 350 truncate:
 351                 ext4_truncate_failed_write(inode);
 352                 /*
 353                  * If the truncate operation failed early, then the inode may
 354                  * still be on the orphan list. In that case, we need to try
 355                  * remove the inode from the in-memory linked list.
 356                  */
 357                 if (inode->i_nlink)
 358                         ext4_orphan_del(NULL, inode);
 359         }
 360
 361         return written;
 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 offset = iocb->ki_pos;
 368         struct inode *inode = file_inode(iocb->ki_filp);
 369
 370         if (error)
 371                 return error;
 372
 373         if (size && flags & IOMAP_DIO_UNWRITTEN)
 374                 return ext4_convert_unwritten_extents(NULL, inode,
 375                                                       offset, size);
 376
 377         return 0;
 378 }
 379
 380 static const struct iomap_dio_ops ext4_dio_write_ops = {
 381         .end_io = ext4_dio_write_end_io,
 382 };
 383
 384 /*
 385  * The intention here is to start with shared lock acquired then see if any
 386  * condition requires an exclusive inode lock. If yes, then we restart the
 387  * whole operation by releasing the shared lock and acquiring exclusive lock.
 388  *
 389  * - For unaligned_io we never take shared lock as it may cause data corruption
 390  *   when two unaligned IO tries to modify the same block e.g. while zeroing.
 391  *
 392  * - For extending writes case we don't take the shared lock, since it requires
 393  *   updating inode i_disksize and/or orphan handling with exclusive lock.
 394  *
 395  * - shared locking will only be true mostly with overwrites. Otherwise we will
 396  *   switch to exclusive i_rwsem lock.
 397  */
 398 static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
 399                                      bool *ilock_shared, bool *extend)
 400 {
 401         struct file *file = iocb->ki_filp;
 402         struct inode *inode = file_inode(file);
 403         loff_t offset;
 404         size_t count;
 405         ssize_t ret;
 406
 407 restart:
 408         ret = ext4_generic_write_checks(iocb, from);
 409         if (ret <= 0)
 410                 goto out;
 411
 412         offset = iocb->ki_pos;
 413         count = ret;
 414         if (ext4_extending_io(inode, offset, count))
 415                 *extend = true;
 416         /*
 417          * Determine whether the IO operation will overwrite allocated
 418          * and initialized blocks.
 419          * We need exclusive i_rwsem for changing security info
 420          * in file_modified().
 421          */
 422         if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
 423              !ext4_overwrite_io(inode, offset, count))) {
 424                 inode_unlock_shared(inode);
 425                 *ilock_shared = false;
 426                 inode_lock(inode);
 427                 goto restart;
 428         }
 429
 430         ret = file_modified(file);
 431         if (ret < 0)
 432                 goto out;
 433
 434         return count;
 435 out:
 436         if (*ilock_shared)
 437                 inode_unlock_shared(inode);
 438         else
 439                 inode_unlock(inode);
 440         return ret;
 441 }
 442
 443 static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 444 {
 445         ssize_t ret;
 446         handle_t *handle;
 447         struct inode *inode = file_inode(iocb->ki_filp);
 448         loff_t offset = iocb->ki_pos;
 449         size_t count = iov_iter_count(from);
 450         const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
 451         bool extend = false, unaligned_io = false;
 452         bool ilock_shared = true;
 453
 454         /*
 455          * We initially start with shared inode lock unless it is
 456          * unaligned IO which needs exclusive lock anyways.
 457          */
 458         if (ext4_unaligned_io(inode, from, offset)) {
 459                 unaligned_io = true;
 460                 ilock_shared = false;
 461         }
 462         /*
 463          * Quick check here without any i_rwsem lock to see if it is extending
 464          * IO. A more reliable check is done in ext4_dio_write_checks() with
 465          * proper locking in place.
 466          */
 467         if (offset + count > i_size_read(inode))
 468                 ilock_shared = false;
 469
 470         if (iocb->ki_flags & IOCB_NOWAIT) {
 471                 if (ilock_shared) {
 472                         if (!inode_trylock_shared(inode))
 473                                 return -EAGAIN;
 474                 } else {
 475                         if (!inode_trylock(inode))
 476                                 return -EAGAIN;
 477                 }
 478         } else {
 479                 if (ilock_shared)
 480                         inode_lock_shared(inode);
 481                 else
 482                         inode_lock(inode);
 483         }
 484
 485         /* Fallback to buffered I/O if the inode does not support direct I/O. */
 486         if (!ext4_dio_supported(inode)) {
 487                 if (ilock_shared)
 488                         inode_unlock_shared(inode);
 489                 else
 490                         inode_unlock(inode);
 491                 return ext4_buffered_write_iter(iocb, from);
 492         }
 493
 494         ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend);
 495         if (ret <= 0)
 496                 return ret;
 497
 498         offset = iocb->ki_pos;
 499         count = ret;
 500
 501         /*
 502          * Unaligned direct IO must be serialized among each other as zeroing
 503          * of partial blocks of two competing unaligned IOs can result in data
 504          * corruption.
 505          *
 506          * So we make sure we don't allow any unaligned IO in flight.
 507          * For IOs where we need not wait (like unaligned non-AIO DIO),
 508          * below inode_dio_wait() may anyway become a no-op, since we start
 509          * with exclusive lock.
 510          */
 511         if (unaligned_io)
 512                 inode_dio_wait(inode);
 513
 514         if (extend) {
 515                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 516                 if (IS_ERR(handle)) {
 517                         ret = PTR_ERR(handle);
 518                         goto out;
 519                 }
 520
 521                 ret = ext4_orphan_add(handle, inode);
 522                 if (ret) {
 523                         ext4_journal_stop(handle);
 524                         goto out;
 525                 }
 526
 527                 ext4_journal_stop(handle);
 528         }
 529
 530         if (ilock_shared)
 531                 iomap_ops = &ext4_iomap_overwrite_ops;
 532         ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
 533                            is_sync_kiocb(iocb) || unaligned_io || extend);
 534
 535         if (extend)
 536                 ret = ext4_handle_inode_extension(inode, offset, ret, count);
 537
 538 out:
 539         if (ilock_shared)
 540                 inode_unlock_shared(inode);
 541         else
 542                 inode_unlock(inode);
 543
 544         if (ret >= 0 && iov_iter_count(from)) {
 545                 ssize_t err;
 546                 loff_t endbyte;
 547
 548                 offset = iocb->ki_pos;
 549                 err = ext4_buffered_write_iter(iocb, from);
 550                 if (err < 0)
 551                         return err;
 552
 553                 /*
 554                  * We need to ensure that the pages within the page cache for
 555                  * the range covered by this I/O are written to disk and
 556                  * invalidated. This is in attempt to preserve the expected
 557                  * direct I/O semantics in the case we fallback to buffered I/O
 558                  * to complete off the I/O request.
 559                  */
 560                 ret += err;
 561                 endbyte = offset + err - 1;
 562                 err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping,
 563                                                    offset, endbyte);
 564                 if (!err)
 565                         invalidate_mapping_pages(iocb->ki_filp->f_mapping,
 566                                                  offset >> PAGE_SHIFT,
 567                                                  endbyte >> PAGE_SHIFT);
 568         }
 569
 570         return ret;
 571 }
 572
 573 #ifdef CONFIG_FS_DAX
 574 static ssize_t
 575 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
 576 {
 577         ssize_t ret;
 578         size_t count;
 579         loff_t offset;
 580         handle_t *handle;
 581         bool extend = false;
 582         struct inode *inode = file_inode(iocb->ki_filp);
 583
 584         if (iocb->ki_flags & IOCB_NOWAIT) {
 585                 if (!inode_trylock(inode))
 586                         return -EAGAIN;
 587         } else {
 588                 inode_lock(inode);
 589         }
 590
 591         ret = ext4_write_checks(iocb, from);
 592         if (ret <= 0)
 593                 goto out;
 594
 595         offset = iocb->ki_pos;
 596         count = iov_iter_count(from);
 597
 598         if (offset + count > EXT4_I(inode)->i_disksize) {
 599                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 600                 if (IS_ERR(handle)) {
 601                         ret = PTR_ERR(handle);
 602                         goto out;
 603                 }
 604
 605                 ret = ext4_orphan_add(handle, inode);
 606                 if (ret) {
 607                         ext4_journal_stop(handle);
 608                         goto out;
 609                 }
 610
 611                 extend = true;
 612                 ext4_journal_stop(handle);
 613         }
 614
 615         ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
 616
 617         if (extend)
 618                 ret = ext4_handle_inode_extension(inode, offset, ret, count);
 619 out:
 620         inode_unlock(inode);
 621         if (ret > 0)
 622                 ret = generic_write_sync(iocb, ret);
 623         return ret;
 624 }
 625 #endif
 626
 627 static ssize_t
 628 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 629 {
 630         struct inode *inode = file_inode(iocb->ki_filp);
 631
 632         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 633                 return -EIO;
 634
 635 #ifdef CONFIG_FS_DAX
 636         if (IS_DAX(inode))
 637                 return ext4_dax_write_iter(iocb, from);
 638 #endif
 639         if (iocb->ki_flags & IOCB_DIRECT)
 640                 return ext4_dio_write_iter(iocb, from);
 641
 642         return ext4_buffered_write_iter(iocb, from);
 643 }
 644
 645 #ifdef CONFIG_FS_DAX
 646 static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
 647                 enum page_entry_size pe_size)
 648 {
 649         int error = 0;
 650         vm_fault_t result;
 651         int retries = 0;
 652         handle_t *handle = NULL;
 653         struct inode *inode = file_inode(vmf->vma->vm_file);
 654         struct super_block *sb = inode->i_sb;
 655
 656         /*
 657          * We have to distinguish real writes from writes which will result in a
 658          * COW page; COW writes should *not* poke the journal (the file will not
 659          * be changed). Doing so would cause unintended failures when mounted
 660          * read-only.
 661          *
 662          * We check for VM_SHARED rather than vmf->cow_page since the latter is
 663          * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
 664          * other sizes, dax_iomap_fault will handle splitting / fallback so that
 665          * we eventually come back with a COW page.
 666          */
 667         bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
 668                 (vmf->vma->vm_flags & VM_SHARED);
 669         pfn_t pfn;
 670
 671         if (write) {
 672                 sb_start_pagefault(sb);
 673                 file_update_time(vmf->vma->vm_file);
 674                 down_read(&EXT4_I(inode)->i_mmap_sem);
 675 retry:
 676                 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
 677                                                EXT4_DATA_TRANS_BLOCKS(sb));
 678                 if (IS_ERR(handle)) {
 679                         up_read(&EXT4_I(inode)->i_mmap_sem);
 680                         sb_end_pagefault(sb);
 681                         return VM_FAULT_SIGBUS;
 682                 }
 683         } else {
 684                 down_read(&EXT4_I(inode)->i_mmap_sem);
 685         }
 686         result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
 687         if (write) {
 688                 ext4_journal_stop(handle);
 689
 690                 if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
 691                     ext4_should_retry_alloc(sb, &retries))
 692                         goto retry;
 693                 /* Handling synchronous page fault? */
 694                 if (result & VM_FAULT_NEEDDSYNC)
 695                         result = dax_finish_sync_fault(vmf, pe_size, pfn);
 696                 up_read(&EXT4_I(inode)->i_mmap_sem);
 697                 sb_end_pagefault(sb);
 698         } else {
 699                 up_read(&EXT4_I(inode)->i_mmap_sem);
 700         }
 701
 702         return result;
 703 }
 704
 705 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
 706 {
 707         return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
 708 }
 709
 710 static const struct vm_operations_struct ext4_dax_vm_ops = {
 711         .fault          = ext4_dax_fault,
 712         .huge_fault     = ext4_dax_huge_fault,
 713         .page_mkwrite   = ext4_dax_fault,
 714         .pfn_mkwrite    = ext4_dax_fault,
 715 };
 716 #else
 717 #define ext4_dax_vm_ops ext4_file_vm_ops
 718 #endif
 719
 720 static const struct vm_operations_struct ext4_file_vm_ops = {
 721         .fault          = ext4_filemap_fault,
 722         .map_pages      = filemap_map_pages,
 723         .page_mkwrite   = ext4_page_mkwrite,
 724 };
 725
 726 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 727 {
 728         struct inode *inode = file->f_mapping->host;
 729         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 730         struct dax_device *dax_dev = sbi->s_daxdev;
 731
 732         if (unlikely(ext4_forced_shutdown(sbi)))
 733                 return -EIO;
 734
 735         /*
 736          * We don't support synchronous mappings for non-DAX files and
 737          * for DAX files if underneath dax_device is not synchronous.
 738          */
 739         if (!daxdev_mapping_supported(vma, dax_dev))
 740                 return -EOPNOTSUPP;
 741
 742         file_accessed(file);
 743         if (IS_DAX(file_inode(file))) {
 744                 vma->vm_ops = &ext4_dax_vm_ops;
 745                 vma->vm_flags |= VM_HUGEPAGE;
 746         } else {
 747                 vma->vm_ops = &ext4_file_vm_ops;
 748         }
 749         return 0;
 750 }
 751
 752 static int ext4_sample_last_mounted(struct super_block *sb,
 753                                     struct vfsmount *mnt)
 754 {
 755         struct ext4_sb_info *sbi = EXT4_SB(sb);
 756         struct path path;
 757         char buf[64], *cp;
 758         handle_t *handle;
 759         int err;
 760
 761         if (likely(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED))
 762                 return 0;
 763
 764         if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
 765                 return 0;
 766
 767         sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;
 768         /*
 769          * Sample where the filesystem has been mounted and
 770          * store it in the superblock for sysadmin convenience
 771          * when trying to sort through large numbers of block
 772          * devices or filesystem images.
 773          */
 774         memset(buf, 0, sizeof(buf));
 775         path.mnt = mnt;
 776         path.dentry = mnt->mnt_root;
 777         cp = d_path(&path, buf, sizeof(buf));
 778         err = 0;
 779         if (IS_ERR(cp))
 780                 goto out;
 781
 782         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 783         err = PTR_ERR(handle);
 784         if (IS_ERR(handle))
 785                 goto out;
 786         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 787         err = ext4_journal_get_write_access(handle, sbi->s_sbh);
 788         if (err)
 789                 goto out_journal;
 790         strlcpy(sbi->s_es->s_last_mounted, cp,
 791                 sizeof(sbi->s_es->s_last_mounted));
 792         ext4_handle_dirty_super(handle, sb);
 793 out_journal:
 794         ext4_journal_stop(handle);
 795 out:
 796         sb_end_intwrite(sb);
 797         return err;
 798 }
 799
 800 static int ext4_file_open(struct inode * inode, struct file * filp)
 801 {
 802         int ret;
 803
 804         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 805                 return -EIO;
 806
 807         ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
 808         if (ret)
 809                 return ret;
 810
 811         ret = fscrypt_file_open(inode, filp);
 812         if (ret)
 813                 return ret;
 814
 815         ret = fsverity_file_open(inode, filp);
 816         if (ret)
 817                 return ret;
 818
 819         /*
 820          * Set up the jbd2_inode if we are opening the inode for
 821          * writing and the journal is present
 822          */
 823         if (filp->f_mode & FMODE_WRITE) {
 824                 ret = ext4_inode_attach_jinode(inode);
 825                 if (ret < 0)
 826                         return ret;
 827         }
 828
 829         filp->f_mode |= FMODE_NOWAIT;
 830         return dquot_file_open(inode, filp);
 831 }
 832
 833 /*
 834  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 835  * by calling generic_file_llseek_size() with the appropriate maxbytes
 836  * value for each.
 837  */
 838 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 839 {
 840         struct inode *inode = file->f_mapping->host;
 841         loff_t maxbytes;
 842
 843         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 844                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 845         else
 846                 maxbytes = inode->i_sb->s_maxbytes;
 847
 848         switch (whence) {
 849         default:
 850                 return generic_file_llseek_size(file, offset, whence,
 851                                                 maxbytes, i_size_read(inode));
 852         case SEEK_HOLE:
 853                 inode_lock_shared(inode);
 854                 offset = iomap_seek_hole(inode, offset,
 855                                          &ext4_iomap_report_ops);
 856                 inode_unlock_shared(inode);
 857                 break;
 858         case SEEK_DATA:
 859                 inode_lock_shared(inode);
 860                 offset = iomap_seek_data(inode, offset,
 861                                          &ext4_iomap_report_ops);
 862                 inode_unlock_shared(inode);
 863                 break;
 864         }
 865
 866         if (offset < 0)
 867                 return offset;
 868         return vfs_setpos(file, offset, maxbytes);
 869 }
 870
 871 const struct file_operations ext4_file_operations = {
 872         .llseek         = ext4_llseek,
 873         .read_iter      = ext4_file_read_iter,
 874         .write_iter     = ext4_file_write_iter,
 875         .iopoll         = iomap_dio_iopoll,
 876         .unlocked_ioctl = ext4_ioctl,
 877 #ifdef CONFIG_COMPAT
 878         .compat_ioctl   = ext4_compat_ioctl,
 879 #endif
 880         .mmap           = ext4_file_mmap,
 881         .mmap_supported_flags = MAP_SYNC,
 882         .open           = ext4_file_open,
 883         .release        = ext4_release_file,
 884         .fsync          = ext4_sync_file,
 885         .get_unmapped_area = thp_get_unmapped_area,
 886         .splice_read    = generic_file_splice_read,
 887         .splice_write   = iter_file_splice_write,
 888         .fallocate      = ext4_fallocate,
 889 };
 890
 891 const struct inode_operations ext4_file_inode_operations = {
 892         .setattr        = ext4_setattr,
 893         .getattr        = ext4_file_getattr,
 894         .listxattr      = ext4_listxattr,
 895         .get_acl        = ext4_get_acl,
 896         .set_acl        = ext4_set_acl,
 897         .fiemap         = ext4_fiemap,
 898 };
 899