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 written, size_t count)
 300 {
 301         handle_t *handle;
 302         bool truncate = false;
 303         u8 blkbits = inode->i_blkbits;
 304         ext4_lblk_t written_blk, end_blk;
 305         int ret;
 306
 307         /*
 308          * Note that EXT4_I(inode)->i_disksize can get extended up to
 309          * inode->i_size while the I/O was running due to writeback of delalloc
 310          * blocks. But, the code in ext4_iomap_alloc() is careful to use
 311          * zeroed/unwritten extents if this is possible; thus we won't leave
 312          * uninitialized blocks in a file even if we didn't succeed in writing
 313          * as much as we intended.
 314          */
 315         WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize);
 316         if (offset + count <= EXT4_I(inode)->i_disksize) {
 317                 /*
 318                  * We need to ensure that the inode is removed from the orphan
 319                  * list if it has been added prematurely, due to writeback of
 320                  * delalloc blocks.
 321                  */
 322                 if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
 323                         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 324
 325                         if (IS_ERR(handle)) {
 326                                 ext4_orphan_del(NULL, inode);
 327                                 return PTR_ERR(handle);
 328                         }
 329
 330                         ext4_orphan_del(handle, inode);
 331                         ext4_journal_stop(handle);
 332                 }
 333
 334                 return written;
 335         }
 336
 337         if (written < 0)
 338                 goto truncate;
 339
 340         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 341         if (IS_ERR(handle)) {
 342                 written = PTR_ERR(handle);
 343                 goto truncate;
 344         }
 345
 346         if (ext4_update_inode_size(inode, offset + written)) {
 347                 ret = ext4_mark_inode_dirty(handle, inode);
 348                 if (unlikely(ret)) {
 349                         written = ret;
 350                         ext4_journal_stop(handle);
 351                         goto truncate;
 352                 }
 353         }
 354
 355         /*
 356          * We may need to truncate allocated but not written blocks beyond EOF.
 357          */
 358         written_blk = ALIGN(offset + written, 1 << blkbits);
 359         end_blk = ALIGN(offset + count, 1 << blkbits);
 360         if (written_blk < end_blk && ext4_can_truncate(inode))
 361                 truncate = true;
 362
 363         /*
 364          * Remove the inode from the orphan list if it has been extended and
 365          * everything went OK.
 366          */
 367         if (!truncate && inode->i_nlink)
 368                 ext4_orphan_del(handle, inode);
 369         ext4_journal_stop(handle);
 370
 371         if (truncate) {
 372 truncate:
 373                 ext4_truncate_failed_write(inode);
 374                 /*
 375                  * If the truncate operation failed early, then the inode may
 376                  * still be on the orphan list. In that case, we need to try
 377                  * remove the inode from the in-memory linked list.
 378                  */
 379                 if (inode->i_nlink)
 380                         ext4_orphan_del(NULL, inode);
 381         }
 382
 383         return written;
 384 }
 385
 386 static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
 387                                  int error, unsigned int flags)
 388 {
 389         loff_t pos = iocb->ki_pos;
 390         struct inode *inode = file_inode(iocb->ki_filp);
 391
 392         if (error)
 393                 return error;
 394
 395         if (size && flags & IOMAP_DIO_UNWRITTEN) {
 396                 error = ext4_convert_unwritten_extents(NULL, inode, pos, size);
 397                 if (error < 0)
 398                         return error;
 399         }
 400         /*
 401          * If we are extending the file, we have to update i_size here before
 402          * page cache gets invalidated in iomap_dio_rw(). Otherwise racing
 403          * buffered reads could zero out too much from page cache pages. Update
 404          * of on-disk size will happen later in ext4_dio_write_iter() where
 405          * we have enough information to also perform orphan list handling etc.
 406          * Note that we perform all extending writes synchronously under
 407          * i_rwsem held exclusively so i_size update is safe here in that case.
 408          * If the write was not extending, we cannot see pos > i_size here
 409          * because operations reducing i_size like truncate wait for all
 410          * outstanding DIO before updating i_size.
 411          */
 412         pos += size;
 413         if (pos > i_size_read(inode))
 414                 i_size_write(inode, pos);
 415
 416         return 0;
 417 }
 418
 419 static const struct iomap_dio_ops ext4_dio_write_ops = {
 420         .end_io = ext4_dio_write_end_io,
 421 };
 422
 423 /*
 424  * The intention here is to start with shared lock acquired then see if any
 425  * condition requires an exclusive inode lock. If yes, then we restart the
 426  * whole operation by releasing the shared lock and acquiring exclusive lock.
 427  *
 428  * - For unaligned_io we never take shared lock as it may cause data corruption
 429  *   when two unaligned IO tries to modify the same block e.g. while zeroing.
 430  *
 431  * - For extending writes case we don't take the shared lock, since it requires
 432  *   updating inode i_disksize and/or orphan handling with exclusive lock.
 433  *
 434  * - shared locking will only be true mostly with overwrites. Otherwise we will
 435  *   switch to exclusive i_rwsem lock.
 436  */
 437 static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
 438                                      bool *ilock_shared, bool *extend)
 439 {
 440         struct file *file = iocb->ki_filp;
 441         struct inode *inode = file_inode(file);
 442         loff_t offset;
 443         size_t count;
 444         ssize_t ret;
 445
 446 restart:
 447         ret = ext4_generic_write_checks(iocb, from);
 448         if (ret <= 0)
 449                 goto out;
 450
 451         offset = iocb->ki_pos;
 452         count = ret;
 453         if (ext4_extending_io(inode, offset, count))
 454                 *extend = true;
 455         /*
 456          * Determine whether the IO operation will overwrite allocated
 457          * and initialized blocks.
 458          * We need exclusive i_rwsem for changing security info
 459          * in file_modified().
 460          */
 461         if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
 462              !ext4_overwrite_io(inode, offset, count))) {
 463                 if (iocb->ki_flags & IOCB_NOWAIT) {
 464                         ret = -EAGAIN;
 465                         goto out;
 466                 }
 467                 inode_unlock_shared(inode);
 468                 *ilock_shared = false;
 469                 inode_lock(inode);
 470                 goto restart;
 471         }
 472
 473         ret = file_modified(file);
 474         if (ret < 0)
 475                 goto out;
 476
 477         return count;
 478 out:
 479         if (*ilock_shared)
 480                 inode_unlock_shared(inode);
 481         else
 482                 inode_unlock(inode);
 483         return ret;
 484 }
 485
 486 static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 487 {
 488         ssize_t ret;
 489         handle_t *handle;
 490         struct inode *inode = file_inode(iocb->ki_filp);
 491         loff_t offset = iocb->ki_pos;
 492         size_t count = iov_iter_count(from);
 493         const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
 494         bool extend = false, unaligned_io = false;
 495         bool ilock_shared = true;
 496
 497         /*
 498          * We initially start with shared inode lock unless it is
 499          * unaligned IO which needs exclusive lock anyways.
 500          */
 501         if (ext4_unaligned_io(inode, from, offset)) {
 502                 unaligned_io = true;
 503                 ilock_shared = false;
 504         }
 505         /*
 506          * Quick check here without any i_rwsem lock to see if it is extending
 507          * IO. A more reliable check is done in ext4_dio_write_checks() with
 508          * proper locking in place.
 509          */
 510         if (offset + count > i_size_read(inode))
 511                 ilock_shared = false;
 512
 513         if (iocb->ki_flags & IOCB_NOWAIT) {
 514                 if (ilock_shared) {
 515                         if (!inode_trylock_shared(inode))
 516                                 return -EAGAIN;
 517                 } else {
 518                         if (!inode_trylock(inode))
 519                                 return -EAGAIN;
 520                 }
 521         } else {
 522                 if (ilock_shared)
 523                         inode_lock_shared(inode);
 524                 else
 525                         inode_lock(inode);
 526         }
 527
 528         /* Fallback to buffered I/O if the inode does not support direct I/O. */
 529         if (!ext4_should_use_dio(iocb, from)) {
 530                 if (ilock_shared)
 531                         inode_unlock_shared(inode);
 532                 else
 533                         inode_unlock(inode);
 534                 return ext4_buffered_write_iter(iocb, from);
 535         }
 536
 537         ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend);
 538         if (ret <= 0)
 539                 return ret;
 540
 541         /* if we're going to block and IOCB_NOWAIT is set, return -EAGAIN */
 542         if ((iocb->ki_flags & IOCB_NOWAIT) && (unaligned_io || extend)) {
 543                 ret = -EAGAIN;
 544                 goto out;
 545         }
 546         /*
 547          * Make sure inline data cannot be created anymore since we are going
 548          * to allocate blocks for DIO. We know the inode does not have any
 549          * inline data now because ext4_dio_supported() checked for that.
 550          */
 551         ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
 552
 553         offset = iocb->ki_pos;
 554         count = ret;
 555
 556         /*
 557          * Unaligned direct IO must be serialized among each other as zeroing
 558          * of partial blocks of two competing unaligned IOs can result in data
 559          * corruption.
 560          *
 561          * So we make sure we don't allow any unaligned IO in flight.
 562          * For IOs where we need not wait (like unaligned non-AIO DIO),
 563          * below inode_dio_wait() may anyway become a no-op, since we start
 564          * with exclusive lock.
 565          */
 566         if (unaligned_io)
 567                 inode_dio_wait(inode);
 568
 569         if (extend) {
 570                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 571                 if (IS_ERR(handle)) {
 572                         ret = PTR_ERR(handle);
 573                         goto out;
 574                 }
 575
 576                 ret = ext4_orphan_add(handle, inode);
 577                 if (ret) {
 578                         ext4_journal_stop(handle);
 579                         goto out;
 580                 }
 581
 582                 ext4_journal_stop(handle);
 583         }
 584
 585         if (ilock_shared)
 586                 iomap_ops = &ext4_iomap_overwrite_ops;
 587         ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
 588                            (unaligned_io || extend) ? IOMAP_DIO_FORCE_WAIT : 0,
 589                            NULL, 0);
 590         if (ret == -ENOTBLK)
 591                 ret = 0;
 592
 593         if (extend)
 594                 ret = ext4_handle_inode_extension(inode, offset, ret, count);
 595
 596 out:
 597         if (ilock_shared)
 598                 inode_unlock_shared(inode);
 599         else
 600                 inode_unlock(inode);
 601
 602         if (ret >= 0 && iov_iter_count(from)) {
 603                 ssize_t err;
 604                 loff_t endbyte;
 605
 606                 offset = iocb->ki_pos;
 607                 err = ext4_buffered_write_iter(iocb, from);
 608                 if (err < 0)
 609                         return err;
 610
 611                 /*
 612                  * We need to ensure that the pages within the page cache for
 613                  * the range covered by this I/O are written to disk and
 614                  * invalidated. This is in attempt to preserve the expected
 615                  * direct I/O semantics in the case we fallback to buffered I/O
 616                  * to complete off the I/O request.
 617                  */
 618                 ret += err;
 619                 endbyte = offset + err - 1;
 620                 err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping,
 621                                                    offset, endbyte);
 622                 if (!err)
 623                         invalidate_mapping_pages(iocb->ki_filp->f_mapping,
 624                                                  offset >> PAGE_SHIFT,
 625                                                  endbyte >> PAGE_SHIFT);
 626         }
 627
 628         return ret;
 629 }
 630
 631 #ifdef CONFIG_FS_DAX
 632 static ssize_t
 633 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
 634 {
 635         ssize_t ret;
 636         size_t count;
 637         loff_t offset;
 638         handle_t *handle;
 639         bool extend = false;
 640         struct inode *inode = file_inode(iocb->ki_filp);
 641
 642         if (iocb->ki_flags & IOCB_NOWAIT) {
 643                 if (!inode_trylock(inode))
 644                         return -EAGAIN;
 645         } else {
 646                 inode_lock(inode);
 647         }
 648
 649         ret = ext4_write_checks(iocb, from);
 650         if (ret <= 0)
 651                 goto out;
 652
 653         offset = iocb->ki_pos;
 654         count = iov_iter_count(from);
 655
 656         if (offset + count > EXT4_I(inode)->i_disksize) {
 657                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 658                 if (IS_ERR(handle)) {
 659                         ret = PTR_ERR(handle);
 660                         goto out;
 661                 }
 662
 663                 ret = ext4_orphan_add(handle, inode);
 664                 if (ret) {
 665                         ext4_journal_stop(handle);
 666                         goto out;
 667                 }
 668
 669                 extend = true;
 670                 ext4_journal_stop(handle);
 671         }
 672
 673         ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
 674
 675         if (extend)
 676                 ret = ext4_handle_inode_extension(inode, offset, ret, count);
 677 out:
 678         inode_unlock(inode);
 679         if (ret > 0)
 680                 ret = generic_write_sync(iocb, ret);
 681         return ret;
 682 }
 683 #endif
 684
 685 static ssize_t
 686 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 687 {
 688         struct inode *inode = file_inode(iocb->ki_filp);
 689
 690         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 691                 return -EIO;
 692
 693 #ifdef CONFIG_FS_DAX
 694         if (IS_DAX(inode))
 695                 return ext4_dax_write_iter(iocb, from);
 696 #endif
 697         if (iocb->ki_flags & IOCB_DIRECT)
 698                 return ext4_dio_write_iter(iocb, from);
 699         else
 700                 return ext4_buffered_write_iter(iocb, from);
 701 }
 702
 703 #ifdef CONFIG_FS_DAX
 704 static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
 705                 enum page_entry_size pe_size)
 706 {
 707         int error = 0;
 708         vm_fault_t result;
 709         int retries = 0;
 710         handle_t *handle = NULL;
 711         struct inode *inode = file_inode(vmf->vma->vm_file);
 712         struct super_block *sb = inode->i_sb;
 713
 714         /*
 715          * We have to distinguish real writes from writes which will result in a
 716          * COW page; COW writes should *not* poke the journal (the file will not
 717          * be changed). Doing so would cause unintended failures when mounted
 718          * read-only.
 719          *
 720          * We check for VM_SHARED rather than vmf->cow_page since the latter is
 721          * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
 722          * other sizes, dax_iomap_fault will handle splitting / fallback so that
 723          * we eventually come back with a COW page.
 724          */
 725         bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
 726                 (vmf->vma->vm_flags & VM_SHARED);
 727         struct address_space *mapping = vmf->vma->vm_file->f_mapping;
 728         pfn_t pfn;
 729
 730         if (write) {
 731                 sb_start_pagefault(sb);
 732                 file_update_time(vmf->vma->vm_file);
 733                 filemap_invalidate_lock_shared(mapping);
 734 retry:
 735                 handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
 736                                                EXT4_DATA_TRANS_BLOCKS(sb));
 737                 if (IS_ERR(handle)) {
 738                         filemap_invalidate_unlock_shared(mapping);
 739                         sb_end_pagefault(sb);
 740                         return VM_FAULT_SIGBUS;
 741                 }
 742         } else {
 743                 filemap_invalidate_lock_shared(mapping);
 744         }
 745         result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
 746         if (write) {
 747                 ext4_journal_stop(handle);
 748
 749                 if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
 750                     ext4_should_retry_alloc(sb, &retries))
 751                         goto retry;
 752                 /* Handling synchronous page fault? */
 753                 if (result & VM_FAULT_NEEDDSYNC)
 754                         result = dax_finish_sync_fault(vmf, pe_size, pfn);
 755                 filemap_invalidate_unlock_shared(mapping);
 756                 sb_end_pagefault(sb);
 757         } else {
 758                 filemap_invalidate_unlock_shared(mapping);
 759         }
 760
 761         return result;
 762 }
 763
 764 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
 765 {
 766         return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
 767 }
 768
 769 static const struct vm_operations_struct ext4_dax_vm_ops = {
 770         .fault          = ext4_dax_fault,
 771         .huge_fault     = ext4_dax_huge_fault,
 772         .page_mkwrite   = ext4_dax_fault,
 773         .pfn_mkwrite    = ext4_dax_fault,
 774 };
 775 #else
 776 #define ext4_dax_vm_ops ext4_file_vm_ops
 777 #endif
 778
 779 static const struct vm_operations_struct ext4_file_vm_ops = {
 780         .fault          = filemap_fault,
 781         .map_pages      = filemap_map_pages,
 782         .page_mkwrite   = ext4_page_mkwrite,
 783 };
 784
 785 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 786 {
 787         struct inode *inode = file->f_mapping->host;
 788         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 789         struct dax_device *dax_dev = sbi->s_daxdev;
 790
 791         if (unlikely(ext4_forced_shutdown(sbi)))
 792                 return -EIO;
 793
 794         /*
 795          * We don't support synchronous mappings for non-DAX files and
 796          * for DAX files if underneath dax_device is not synchronous.
 797          */
 798         if (!daxdev_mapping_supported(vma, dax_dev))
 799                 return -EOPNOTSUPP;
 800
 801         file_accessed(file);
 802         if (IS_DAX(file_inode(file))) {
 803                 vma->vm_ops = &ext4_dax_vm_ops;
 804                 vma->vm_flags |= VM_HUGEPAGE;
 805         } else {
 806                 vma->vm_ops = &ext4_file_vm_ops;
 807         }
 808         return 0;
 809 }
 810
 811 static int ext4_sample_last_mounted(struct super_block *sb,
 812                                     struct vfsmount *mnt)
 813 {
 814         struct ext4_sb_info *sbi = EXT4_SB(sb);
 815         struct path path;
 816         char buf[64], *cp;
 817         handle_t *handle;
 818         int err;
 819
 820         if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED)))
 821                 return 0;
 822
 823         if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
 824                 return 0;
 825
 826         ext4_set_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED);
 827         /*
 828          * Sample where the filesystem has been mounted and
 829          * store it in the superblock for sysadmin convenience
 830          * when trying to sort through large numbers of block
 831          * devices or filesystem images.
 832          */
 833         memset(buf, 0, sizeof(buf));
 834         path.mnt = mnt;
 835         path.dentry = mnt->mnt_root;
 836         cp = d_path(&path, buf, sizeof(buf));
 837         err = 0;
 838         if (IS_ERR(cp))
 839                 goto out;
 840
 841         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
 842         err = PTR_ERR(handle);
 843         if (IS_ERR(handle))
 844                 goto out;
 845         BUFFER_TRACE(sbi->s_sbh, "get_write_access");
 846         err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh,
 847                                             EXT4_JTR_NONE);
 848         if (err)
 849                 goto out_journal;
 850         lock_buffer(sbi->s_sbh);
 851         strncpy(sbi->s_es->s_last_mounted, cp,
 852                 sizeof(sbi->s_es->s_last_mounted));
 853         ext4_superblock_csum_set(sb);
 854         unlock_buffer(sbi->s_sbh);
 855         ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
 856 out_journal:
 857         ext4_journal_stop(handle);
 858 out:
 859         sb_end_intwrite(sb);
 860         return err;
 861 }
 862
 863 static int ext4_file_open(struct inode *inode, struct file *filp)
 864 {
 865         int ret;
 866
 867         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
 868                 return -EIO;
 869
 870         ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
 871         if (ret)
 872                 return ret;
 873
 874         ret = fscrypt_file_open(inode, filp);
 875         if (ret)
 876                 return ret;
 877
 878         ret = fsverity_file_open(inode, filp);
 879         if (ret)
 880                 return ret;
 881
 882         /*
 883          * Set up the jbd2_inode if we are opening the inode for
 884          * writing and the journal is present
 885          */
 886         if (filp->f_mode & FMODE_WRITE) {
 887                 ret = ext4_inode_attach_jinode(inode);
 888                 if (ret < 0)
 889                         return ret;
 890         }
 891
 892         filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
 893         return dquot_file_open(inode, filp);
 894 }
 895
 896 /*
 897  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
 898  * by calling generic_file_llseek_size() with the appropriate maxbytes
 899  * value for each.
 900  */
 901 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 902 {
 903         struct inode *inode = file->f_mapping->host;
 904         loff_t maxbytes;
 905
 906         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 907                 maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
 908         else
 909                 maxbytes = inode->i_sb->s_maxbytes;
 910
 911         switch (whence) {
 912         default:
 913                 return generic_file_llseek_size(file, offset, whence,
 914                                                 maxbytes, i_size_read(inode));
 915         case SEEK_HOLE:
 916                 inode_lock_shared(inode);
 917                 offset = iomap_seek_hole(inode, offset,
 918                                          &ext4_iomap_report_ops);
 919                 inode_unlock_shared(inode);
 920                 break;
 921         case SEEK_DATA:
 922                 inode_lock_shared(inode);
 923                 offset = iomap_seek_data(inode, offset,
 924                                          &ext4_iomap_report_ops);
 925                 inode_unlock_shared(inode);
 926                 break;
 927         }
 928
 929         if (offset < 0)
 930                 return offset;
 931         return vfs_setpos(file, offset, maxbytes);
 932 }
 933
 934 const struct file_operations ext4_file_operations = {
 935         .llseek         = ext4_llseek,
 936         .read_iter      = ext4_file_read_iter,
 937         .write_iter     = ext4_file_write_iter,
 938         .iopoll         = iocb_bio_iopoll,
 939         .unlocked_ioctl = ext4_ioctl,
 940 #ifdef CONFIG_COMPAT
 941         .compat_ioctl   = ext4_compat_ioctl,
 942 #endif
 943         .mmap           = ext4_file_mmap,
 944         .mmap_supported_flags = MAP_SYNC,
 945         .open           = ext4_file_open,
 946         .release        = ext4_release_file,
 947         .fsync          = ext4_sync_file,
 948         .get_unmapped_area = thp_get_unmapped_area,
 949         .splice_read    = generic_file_splice_read,
 950         .splice_write   = iter_file_splice_write,
 951         .fallocate      = ext4_fallocate,
 952 };
 953
 954 const struct inode_operations ext4_file_inode_operations = {
 955         .setattr        = ext4_setattr,
 956         .getattr        = ext4_file_getattr,
 957         .listxattr      = ext4_listxattr,
 958         .get_acl        = ext4_get_acl,
 959         .set_acl        = ext4_set_acl,
 960         .fiemap         = ext4_fiemap,
 961         .fileattr_get   = ext4_fileattr_get,
 962         .fileattr_set   = ext4_fileattr_set,
 963 };
 964