include/linux/blkdev_compat.h

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright (C) 2011 Lawrence Livermore National Security, LLC.
  24  * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
  25  * Written by Brian Behlendorf <behlendorf1@llnl.gov>.
  26  * LLNL-CODE-403049.
  27  */
  28
  29 #ifndef _ZFS_BLKDEV_H
  30 #define _ZFS_BLKDEV_H
  31
  32 #include <linux/blkdev.h>
  33 #include <linux/elevator.h>
  34 #include <linux/backing-dev.h>
  35 #include <linux/hdreg.h>
  36
  37 #ifndef HAVE_FMODE_T
  38 typedef unsigned __bitwise__ fmode_t;
  39 #endif /* HAVE_FMODE_T */
  40
  41 #ifndef HAVE_BLK_QUEUE_FLAG_SET
  42 static inline void
  43 blk_queue_flag_set(unsigned int flag, struct request_queue *q)
  44 {
  45         queue_flag_set(flag, q);
  46 }
  47 #endif
  48
  49 #ifndef HAVE_BLK_QUEUE_FLAG_CLEAR
  50 static inline void
  51 blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
  52 {
  53         queue_flag_clear(flag, q);
  54 }
  55 #endif
  56
  57 /*
  58  * 4.7 - 4.x API,
  59  * The blk_queue_write_cache() interface has replaced blk_queue_flush()
  60  * interface.  However, the new interface is GPL-only thus we implement
  61  * our own trivial wrapper when the GPL-only version is detected.
  62  *
  63  * 2.6.36 - 4.6 API,
  64  * The blk_queue_flush() interface has replaced blk_queue_ordered()
  65  * interface.  However, while the old interface was available to all the
  66  * new one is GPL-only.   Thus if the GPL-only version is detected we
  67  * implement our own trivial helper.
  68  *
  69  * 2.6.x - 2.6.35
  70  * Legacy blk_queue_ordered() interface.
  71  */
  72 static inline void
  73 blk_queue_set_write_cache(struct request_queue *q, bool wc, bool fua)
  74 {
  75 #if defined(HAVE_BLK_QUEUE_WRITE_CACHE_GPL_ONLY)
  76         if (wc)
  77                 blk_queue_flag_set(QUEUE_FLAG_WC, q);
  78         else
  79                 blk_queue_flag_clear(QUEUE_FLAG_WC, q);
  80         if (fua)
  81                 blk_queue_flag_set(QUEUE_FLAG_FUA, q);
  82         else
  83                 blk_queue_flag_clear(QUEUE_FLAG_FUA, q);
  84 #elif defined(HAVE_BLK_QUEUE_WRITE_CACHE)
  85         blk_queue_write_cache(q, wc, fua);
  86 #elif defined(HAVE_BLK_QUEUE_FLUSH_GPL_ONLY)
  87         if (wc)
  88                 q->flush_flags |= REQ_FLUSH;
  89         if (fua)
  90                 q->flush_flags |= REQ_FUA;
  91 #elif defined(HAVE_BLK_QUEUE_FLUSH)
  92         blk_queue_flush(q, (wc ? REQ_FLUSH : 0) | (fua ? REQ_FUA : 0));
  93 #else
  94         blk_queue_ordered(q, QUEUE_ORDERED_DRAIN, NULL);
  95 #endif
  96 }
  97
  98 /*
  99  * Most of the blk_* macros were removed in 2.6.36.  Ostensibly this was
 100  * done to improve readability and allow easier grepping.  However, from
 101  * a portability stand point the macros are helpful.  Therefore the needed
 102  * macros are redefined here if they are missing from the kernel.
 103  */
 104 #ifndef blk_fs_request
 105 #define blk_fs_request(rq)      ((rq)->cmd_type == REQ_TYPE_FS)
 106 #endif
 107
 108 /*
 109  * 2.6.27 API change,
 110  * The blk_queue_stackable() queue flag was added in 2.6.27 to handle dm
 111  * stacking drivers.  Prior to this request stacking drivers were detected
 112  * by checking (q->request_fn == NULL), for earlier kernels we revert to
 113  * this legacy behavior.
 114  */
 115 #ifndef blk_queue_stackable
 116 #define blk_queue_stackable(q)  ((q)->request_fn == NULL)
 117 #endif
 118
 119 /*
 120  * 2.6.34 API change,
 121  * The blk_queue_max_hw_sectors() function replaces blk_queue_max_sectors().
 122  */
 123 #ifndef HAVE_BLK_QUEUE_MAX_HW_SECTORS
 124 #define blk_queue_max_hw_sectors __blk_queue_max_hw_sectors
 125 static inline void
 126 __blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
 127 {
 128         blk_queue_max_sectors(q, max_hw_sectors);
 129 }
 130 #endif
 131
 132 /*
 133  * 2.6.34 API change,
 134  * The blk_queue_max_segments() function consolidates
 135  * blk_queue_max_hw_segments() and blk_queue_max_phys_segments().
 136  */
 137 #ifndef HAVE_BLK_QUEUE_MAX_SEGMENTS
 138 #define blk_queue_max_segments __blk_queue_max_segments
 139 static inline void
 140 __blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
 141 {
 142         blk_queue_max_phys_segments(q, max_segments);
 143         blk_queue_max_hw_segments(q, max_segments);
 144 }
 145 #endif
 146
 147 static inline void
 148 blk_queue_set_read_ahead(struct request_queue *q, unsigned long ra_pages)
 149 {
 150 #ifdef HAVE_BLK_QUEUE_BDI_DYNAMIC
 151         q->backing_dev_info->ra_pages = ra_pages;
 152 #else
 153         q->backing_dev_info.ra_pages = ra_pages;
 154 #endif
 155 }
 156
 157 #ifndef HAVE_GET_DISK_AND_MODULE
 158 static inline struct kobject *
 159 get_disk_and_module(struct gendisk *disk)
 160 {
 161         return (get_disk(disk));
 162 }
 163 #endif
 164
 165 #ifndef HAVE_GET_DISK_RO
 166 static inline int
 167 get_disk_ro(struct gendisk *disk)
 168 {
 169         int policy = 0;
 170
 171         if (disk->part[0])
 172                 policy = disk->part[0]->policy;
 173
 174         return (policy);
 175 }
 176 #endif /* HAVE_GET_DISK_RO */
 177
 178 #ifdef HAVE_BIO_BVEC_ITER
 179 #define BIO_BI_SECTOR(bio)      (bio)->bi_iter.bi_sector
 180 #define BIO_BI_SIZE(bio)        (bio)->bi_iter.bi_size
 181 #define BIO_BI_IDX(bio)         (bio)->bi_iter.bi_idx
 182 #define BIO_BI_SKIP(bio)        (bio)->bi_iter.bi_bvec_done
 183 #define bio_for_each_segment4(bv, bvp, b, i)    \
 184         bio_for_each_segment((bv), (b), (i))
 185 typedef struct bvec_iter bvec_iterator_t;
 186 #else
 187 #define BIO_BI_SECTOR(bio)      (bio)->bi_sector
 188 #define BIO_BI_SIZE(bio)        (bio)->bi_size
 189 #define BIO_BI_IDX(bio)         (bio)->bi_idx
 190 #define BIO_BI_SKIP(bio)        (0)
 191 #define bio_for_each_segment4(bv, bvp, b, i)    \
 192         bio_for_each_segment((bvp), (b), (i))
 193 typedef int bvec_iterator_t;
 194 #endif
 195
 196 /*
 197  * Portable helper for correctly setting the FAILFAST flags.  The
 198  * correct usage has changed 3 times from 2.6.12 to 2.6.38.
 199  */
 200 static inline void
 201 bio_set_flags_failfast(struct block_device *bdev, int *flags)
 202 {
 203 #ifdef CONFIG_BUG
 204         /*
 205          * Disable FAILFAST for loopback devices because of the
 206          * following incorrect BUG_ON() in loop_make_request().
 207          * This support is also disabled for md devices because the
 208          * test suite layers md devices on top of loopback devices.
 209          * This may be removed when the loopback driver is fixed.
 210          *
 211          *   BUG_ON(!lo || (rw != READ && rw != WRITE));
 212          */
 213         if ((MAJOR(bdev->bd_dev) == LOOP_MAJOR) ||
 214             (MAJOR(bdev->bd_dev) == MD_MAJOR))
 215                 return;
 216
 217 #ifdef BLOCK_EXT_MAJOR
 218         if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR)
 219                 return;
 220 #endif /* BLOCK_EXT_MAJOR */
 221 #endif /* CONFIG_BUG */
 222
 223 #if defined(HAVE_BIO_RW_FAILFAST_DTD)
 224         /* BIO_RW_FAILFAST_* preferred interface from 2.6.28 - 2.6.35 */
 225         *flags |= (
 226             (1 << BIO_RW_FAILFAST_DEV) |
 227             (1 << BIO_RW_FAILFAST_TRANSPORT) |
 228             (1 << BIO_RW_FAILFAST_DRIVER));
 229 #elif defined(HAVE_REQ_FAILFAST_MASK)
 230         /*
 231          * REQ_FAILFAST_* preferred interface from 2.6.36 - 2.6.xx,
 232          * the BIO_* and REQ_* flags were unified under REQ_* flags.
 233          */
 234         *flags |= REQ_FAILFAST_MASK;
 235 #else
 236 #error "Undefined block IO FAILFAST interface."
 237 #endif
 238 }
 239
 240 /*
 241  * Maximum disk label length, it may be undefined for some kernels.
 242  */
 243 #ifndef DISK_NAME_LEN
 244 #define DISK_NAME_LEN   32
 245 #endif /* DISK_NAME_LEN */
 246
 247 #ifdef HAVE_BIO_BI_STATUS
 248 static inline int
 249 bi_status_to_errno(blk_status_t status)
 250 {
 251         switch (status) {
 252         case BLK_STS_OK:
 253                 return (0);
 254         case BLK_STS_NOTSUPP:
 255                 return (EOPNOTSUPP);
 256         case BLK_STS_TIMEOUT:
 257                 return (ETIMEDOUT);
 258         case BLK_STS_NOSPC:
 259                 return (ENOSPC);
 260         case BLK_STS_TRANSPORT:
 261                 return (ENOLINK);
 262         case BLK_STS_TARGET:
 263                 return (EREMOTEIO);
 264         case BLK_STS_NEXUS:
 265                 return (EBADE);
 266         case BLK_STS_MEDIUM:
 267                 return (ENODATA);
 268         case BLK_STS_PROTECTION:
 269                 return (EILSEQ);
 270         case BLK_STS_RESOURCE:
 271                 return (ENOMEM);
 272         case BLK_STS_AGAIN:
 273                 return (EAGAIN);
 274         case BLK_STS_IOERR:
 275                 return (EIO);
 276         default:
 277                 return (EIO);
 278         }
 279 }
 280
 281 static inline blk_status_t
 282 errno_to_bi_status(int error)
 283 {
 284         switch (error) {
 285         case 0:
 286                 return (BLK_STS_OK);
 287         case EOPNOTSUPP:
 288                 return (BLK_STS_NOTSUPP);
 289         case ETIMEDOUT:
 290                 return (BLK_STS_TIMEOUT);
 291         case ENOSPC:
 292                 return (BLK_STS_NOSPC);
 293         case ENOLINK:
 294                 return (BLK_STS_TRANSPORT);
 295         case EREMOTEIO:
 296                 return (BLK_STS_TARGET);
 297         case EBADE:
 298                 return (BLK_STS_NEXUS);
 299         case ENODATA:
 300                 return (BLK_STS_MEDIUM);
 301         case EILSEQ:
 302                 return (BLK_STS_PROTECTION);
 303         case ENOMEM:
 304                 return (BLK_STS_RESOURCE);
 305         case EAGAIN:
 306                 return (BLK_STS_AGAIN);
 307         case EIO:
 308                 return (BLK_STS_IOERR);
 309         default:
 310                 return (BLK_STS_IOERR);
 311         }
 312 }
 313 #endif /* HAVE_BIO_BI_STATUS */
 314
 315 /*
 316  * 4.3 API change
 317  * The bio_endio() prototype changed slightly.  These are helper
 318  * macro's to ensure the prototype and invocation are handled.
 319  */
 320 #ifdef HAVE_1ARG_BIO_END_IO_T
 321 #ifdef HAVE_BIO_BI_STATUS
 322 #define BIO_END_IO_ERROR(bio)           bi_status_to_errno(bio->bi_status)
 323 #define BIO_END_IO_PROTO(fn, x, z)      static void fn(struct bio *x)
 324 #define BIO_END_IO(bio, error)          bio_set_bi_status(bio, error)
 325 static inline void
 326 bio_set_bi_status(struct bio *bio, int error)
 327 {
 328         ASSERT3S(error, <=, 0);
 329         bio->bi_status = errno_to_bi_status(-error);
 330         bio_endio(bio);
 331 }
 332 #else
 333 #define BIO_END_IO_ERROR(bio)           (-(bio->bi_error))
 334 #define BIO_END_IO_PROTO(fn, x, z)      static void fn(struct bio *x)
 335 #define BIO_END_IO(bio, error)          bio_set_bi_error(bio, error)
 336 static inline void
 337 bio_set_bi_error(struct bio *bio, int error)
 338 {
 339         ASSERT3S(error, <=, 0);
 340         bio->bi_error = error;
 341         bio_endio(bio);
 342 }
 343 #endif /* HAVE_BIO_BI_STATUS */
 344
 345 #else
 346 #define BIO_END_IO_PROTO(fn, x, z)      static void fn(struct bio *x, int z)
 347 #define BIO_END_IO(bio, error)          bio_endio(bio, error);
 348 #endif /* HAVE_1ARG_BIO_END_IO_T */
 349
 350 /*
 351  * 2.6.38 - 2.6.x API,
 352  *   blkdev_get_by_path()
 353  *   blkdev_put()
 354  *
 355  * 2.6.28 - 2.6.37 API,
 356  *   open_bdev_exclusive()
 357  *   close_bdev_exclusive()
 358  *
 359  * 2.6.12 - 2.6.27 API,
 360  *   open_bdev_excl()
 361  *   close_bdev_excl()
 362  *
 363  * Used to exclusively open a block device from within the kernel.
 364  */
 365 #if defined(HAVE_BLKDEV_GET_BY_PATH)
 366 #define vdev_bdev_open(path, md, hld)   blkdev_get_by_path(path, \
 367                                             (md) | FMODE_EXCL, hld)
 368 #define vdev_bdev_close(bdev, md)       blkdev_put(bdev, (md) | FMODE_EXCL)
 369 #elif defined(HAVE_OPEN_BDEV_EXCLUSIVE)
 370 #define vdev_bdev_open(path, md, hld)   open_bdev_exclusive(path, md, hld)
 371 #define vdev_bdev_close(bdev, md)       close_bdev_exclusive(bdev, md)
 372 #else
 373 #define vdev_bdev_open(path, md, hld)   open_bdev_excl(path, md, hld)
 374 #define vdev_bdev_close(bdev, md)       close_bdev_excl(bdev)
 375 #endif /* HAVE_BLKDEV_GET_BY_PATH | HAVE_OPEN_BDEV_EXCLUSIVE */
 376
 377 /*
 378  * 2.6.22 API change
 379  * The function invalidate_bdev() lost it's second argument because
 380  * it was unused.
 381  */
 382 #ifdef HAVE_1ARG_INVALIDATE_BDEV
 383 #define vdev_bdev_invalidate(bdev)      invalidate_bdev(bdev)
 384 #else
 385 #define vdev_bdev_invalidate(bdev)      invalidate_bdev(bdev, 1)
 386 #endif /* HAVE_1ARG_INVALIDATE_BDEV */
 387
 388 /*
 389  * 2.6.27 API change
 390  * The function was exported for use, prior to this it existed but the
 391  * symbol was not exported.
 392  *
 393  * 4.4.0-6.21 API change for Ubuntu
 394  * lookup_bdev() gained a second argument, FMODE_*, to check inode permissions.
 395  */
 396 #ifdef HAVE_1ARG_LOOKUP_BDEV
 397 #define vdev_lookup_bdev(path)  lookup_bdev(path)
 398 #else
 399 #ifdef HAVE_2ARGS_LOOKUP_BDEV
 400 #define vdev_lookup_bdev(path)  lookup_bdev(path, 0)
 401 #else
 402 #define vdev_lookup_bdev(path)  ERR_PTR(-ENOTSUP)
 403 #endif /* HAVE_2ARGS_LOOKUP_BDEV */
 404 #endif /* HAVE_1ARG_LOOKUP_BDEV */
 405
 406 /*
 407  * 2.6.30 API change
 408  * To ensure good performance preferentially use the physical block size
 409  * for proper alignment.  The physical size is supposed to be the internal
 410  * sector size used by the device.  This is often 4096 byte for AF devices,
 411  * while a smaller 512 byte logical size is supported for compatibility.
 412  *
 413  * Unfortunately, many drives still misreport their physical sector size.
 414  * For devices which are known to lie you may need to manually set this
 415  * at pool creation time with 'zpool create -o ashift=12 ...'.
 416  *
 417  * When the physical block size interface isn't available, we fall back to
 418  * the logical block size interface and then the older hard sector size.
 419  */
 420 #ifdef HAVE_BDEV_PHYSICAL_BLOCK_SIZE
 421 #define vdev_bdev_block_size(bdev)      bdev_physical_block_size(bdev)
 422 #else
 423 #ifdef HAVE_BDEV_LOGICAL_BLOCK_SIZE
 424 #define vdev_bdev_block_size(bdev)      bdev_logical_block_size(bdev)
 425 #else
 426 #define vdev_bdev_block_size(bdev)      bdev_hardsect_size(bdev)
 427 #endif /* HAVE_BDEV_LOGICAL_BLOCK_SIZE */
 428 #endif /* HAVE_BDEV_PHYSICAL_BLOCK_SIZE */
 429
 430 #ifndef HAVE_BIO_SET_OP_ATTRS
 431 /*
 432  * Kernels without bio_set_op_attrs use bi_rw for the bio flags.
 433  */
 434 static inline void
 435 bio_set_op_attrs(struct bio *bio, unsigned rw, unsigned flags)
 436 {
 437         bio->bi_rw |= rw | flags;
 438 }
 439 #endif
 440
 441 /*
 442  * bio_set_flush - Set the appropriate flags in a bio to guarantee
 443  * data are on non-volatile media on completion.
 444  *
 445  * 2.6.X - 2.6.36 API,
 446  *   WRITE_BARRIER - Tells the block layer to commit all previously submitted
 447  *   writes to stable storage before this one is started and that the current
 448  *   write is on stable storage upon completion.  Also prevents reordering
 449  *   on both sides of the current operation.
 450  *
 451  * 2.6.37 - 4.8 API,
 452  *   Introduce  WRITE_FLUSH, WRITE_FUA, and WRITE_FLUSH_FUA flags as a
 453  *   replacement for WRITE_BARRIER to allow expressing richer semantics
 454  *   to the block layer.  It's up to the block layer to implement the
 455  *   semantics correctly. Use the WRITE_FLUSH_FUA flag combination.
 456  *
 457  * 4.8 - 4.9 API,
 458  *   REQ_FLUSH was renamed to REQ_PREFLUSH.  For consistency with previous
 459  *   ZoL releases, prefer the WRITE_FLUSH_FUA flag set if it's available.
 460  *
 461  * 4.10 API,
 462  *   The read/write flags and their modifiers, including WRITE_FLUSH,
 463  *   WRITE_FUA and WRITE_FLUSH_FUA were removed from fs.h in
 464  *   torvalds/linux@70fd7614 and replaced by direct flag modification
 465  *   of the REQ_ flags in bio->bi_opf.  Use REQ_PREFLUSH.
 466  */
 467 static inline void
 468 bio_set_flush(struct bio *bio)
 469 {
 470 #if defined(REQ_PREFLUSH)       /* >= 4.10 */
 471         bio_set_op_attrs(bio, 0, REQ_PREFLUSH);
 472 #elif defined(WRITE_FLUSH_FUA)  /* >= 2.6.37 and <= 4.9 */
 473         bio_set_op_attrs(bio, 0, WRITE_FLUSH_FUA);
 474 #elif defined(WRITE_BARRIER)    /* < 2.6.37 */
 475         bio_set_op_attrs(bio, 0, WRITE_BARRIER);
 476 #else
 477 #error  "Allowing the build will cause bio_set_flush requests to be ignored."
 478 #endif
 479 }
 480
 481 /*
 482  * 4.8 - 4.x API,
 483  *   REQ_OP_FLUSH
 484  *
 485  * 4.8-rc0 - 4.8-rc1,
 486  *   REQ_PREFLUSH
 487  *
 488  * 2.6.36 - 4.7 API,
 489  *   REQ_FLUSH
 490  *
 491  * 2.6.x - 2.6.35 API,
 492  *   HAVE_BIO_RW_BARRIER
 493  *
 494  * Used to determine if a cache flush has been requested.  This check has
 495  * been left intentionally broad in order to cover both a legacy flush
 496  * and the new preflush behavior introduced in Linux 4.8.  This is correct
 497  * in all cases but may have a performance impact for some kernels.  It
 498  * has the advantage of minimizing kernel specific changes in the zvol code.
 499  *
 500  */
 501 static inline boolean_t
 502 bio_is_flush(struct bio *bio)
 503 {
 504 #if defined(HAVE_REQ_OP_FLUSH) && defined(HAVE_BIO_BI_OPF)
 505         return ((bio_op(bio) == REQ_OP_FLUSH) || (bio->bi_opf & REQ_PREFLUSH));
 506 #elif defined(REQ_PREFLUSH) && defined(HAVE_BIO_BI_OPF)
 507         return (bio->bi_opf & REQ_PREFLUSH);
 508 #elif defined(REQ_PREFLUSH) && !defined(HAVE_BIO_BI_OPF)
 509         return (bio->bi_rw & REQ_PREFLUSH);
 510 #elif defined(REQ_FLUSH)
 511         return (bio->bi_rw & REQ_FLUSH);
 512 #elif defined(HAVE_BIO_RW_BARRIER)
 513         return (bio->bi_rw & (1 << BIO_RW_BARRIER));
 514 #else
 515 #error  "Allowing the build will cause flush requests to be ignored."
 516 #endif
 517 }
 518
 519 /*
 520  * 4.8 - 4.x API,
 521  *   REQ_FUA flag moved to bio->bi_opf
 522  *
 523  * 2.6.x - 4.7 API,
 524  *   REQ_FUA
 525  */
 526 static inline boolean_t
 527 bio_is_fua(struct bio *bio)
 528 {
 529 #if defined(HAVE_BIO_BI_OPF)
 530         return (bio->bi_opf & REQ_FUA);
 531 #elif defined(REQ_FUA)
 532         return (bio->bi_rw & REQ_FUA);
 533 #else
 534 #error  "Allowing the build will cause fua requests to be ignored."
 535 #endif
 536 }
 537
 538 /*
 539  * 4.8 - 4.x API,
 540  *   REQ_OP_DISCARD
 541  *
 542  * 2.6.36 - 4.7 API,
 543  *   REQ_DISCARD
 544  *
 545  * 2.6.28 - 2.6.35 API,
 546  *   BIO_RW_DISCARD
 547  *
 548  * In all cases the normal I/O path is used for discards.  The only
 549  * difference is how the kernel tags individual I/Os as discards.
 550  *
 551  * Note that 2.6.32 era kernels provide both BIO_RW_DISCARD and REQ_DISCARD,
 552  * where BIO_RW_DISCARD is the correct interface.  Therefore, it is important
 553  * that the HAVE_BIO_RW_DISCARD check occur before the REQ_DISCARD check.
 554  */
 555 static inline boolean_t
 556 bio_is_discard(struct bio *bio)
 557 {
 558 #if defined(HAVE_REQ_OP_DISCARD)
 559         return (bio_op(bio) == REQ_OP_DISCARD);
 560 #elif defined(HAVE_BIO_RW_DISCARD)
 561         return (bio->bi_rw & (1 << BIO_RW_DISCARD));
 562 #elif defined(REQ_DISCARD)
 563         return (bio->bi_rw & REQ_DISCARD);
 564 #else
 565 /* potentially triggering the DMU_MAX_ACCESS assertion.  */
 566 #error  "Allowing the build will cause discard requests to become writes."
 567 #endif
 568 }
 569
 570 /*
 571  * 4.8 - 4.x API,
 572  *   REQ_OP_SECURE_ERASE
 573  *
 574  * 2.6.36 - 4.7 API,
 575  *   REQ_SECURE
 576  *
 577  * 2.6.x - 2.6.35 API,
 578  *   Unsupported by kernel
 579  */
 580 static inline boolean_t
 581 bio_is_secure_erase(struct bio *bio)
 582 {
 583 #if defined(HAVE_REQ_OP_SECURE_ERASE)
 584         return (bio_op(bio) == REQ_OP_SECURE_ERASE);
 585 #elif defined(REQ_SECURE)
 586         return (bio->bi_rw & REQ_SECURE);
 587 #else
 588         return (0);
 589 #endif
 590 }
 591
 592 /*
 593  * 2.6.33 API change
 594  * Discard granularity and alignment restrictions may now be set.  For
 595  * older kernels which do not support this it is safe to skip it.
 596  */
 597 #ifdef HAVE_DISCARD_GRANULARITY
 598 static inline void
 599 blk_queue_discard_granularity(struct request_queue *q, unsigned int dg)
 600 {
 601         q->limits.discard_granularity = dg;
 602 }
 603 #else
 604 #define blk_queue_discard_granularity(x, dg)    ((void)0)
 605 #endif /* HAVE_DISCARD_GRANULARITY */
 606
 607 /*
 608  * Default Linux IO Scheduler,
 609  * Setting the scheduler to noop will allow the Linux IO scheduler to
 610  * still perform front and back merging, while leaving the request
 611  * ordering and prioritization to the ZFS IO scheduler.
 612  */
 613 #define VDEV_SCHEDULER                  "noop"
 614
 615 /*
 616  * A common holder for vdev_bdev_open() is used to relax the exclusive open
 617  * semantics slightly.  Internal vdev disk callers may pass VDEV_HOLDER to
 618  * allow them to open the device multiple times.  Other kernel callers and
 619  * user space processes which don't pass this value will get EBUSY.  This is
 620  * currently required for the correct operation of hot spares.
 621  */
 622 #define VDEV_HOLDER                     ((void *)0x2401de7)
 623
 624 static inline void
 625 blk_generic_start_io_acct(struct request_queue *q, int rw,
 626     unsigned long sectors, struct hd_struct *part)
 627 {
 628 #if defined(HAVE_GENERIC_IO_ACCT_3ARG)
 629         generic_start_io_acct(rw, sectors, part);
 630 #elif defined(HAVE_GENERIC_IO_ACCT_4ARG)
 631         generic_start_io_acct(q, rw, sectors, part);
 632 #endif
 633 }
 634
 635 static inline void
 636 blk_generic_end_io_acct(struct request_queue *q, int rw,
 637     struct hd_struct *part, unsigned long start_time)
 638 {
 639 #if defined(HAVE_GENERIC_IO_ACCT_3ARG)
 640         generic_end_io_acct(rw, part, start_time);
 641 #elif defined(HAVE_GENERIC_IO_ACCT_4ARG)
 642         generic_end_io_acct(q, rw, part, start_time);
 643 #endif
 644 }
 645
 646 #endif /* _ZFS_BLKDEV_H */