include/sys/zio_impl.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 https://opensource.org/licenses/CDDL-1.0.
  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  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 /*
  27  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
  28  */
  29
  30 #ifndef _ZIO_IMPL_H
  31 #define _ZIO_IMPL_H
  32
  33 #ifdef  __cplusplus
  34 extern "C" {
  35 #endif
  36
  37 /*
  38  * XXX -- Describe ZFS I/O pipeline here. Fill in as needed.
  39  *
  40  * The ZFS I/O pipeline is comprised of various stages which are defined
  41  * in the zio_stage enum below. The individual stages are used to construct
  42  * these basic I/O operations: Read, Write, Free, Claim, and Ioctl.
  43  *
  44  * I/O operations: (XXX - provide detail for each of the operations)
  45  *
  46  * Read:
  47  * Write:
  48  * Free:
  49  * Claim:
  50  * Ioctl:
  51  *
  52  * Although the most common pipeline are used by the basic I/O operations
  53  * above, there are some helper pipelines (one could consider them
  54  * sub-pipelines) which are used internally by the ZIO module and are
  55  * explained below:
  56  *
  57  * Interlock Pipeline:
  58  * The interlock pipeline is the most basic pipeline and is used by all
  59  * of the I/O operations. The interlock pipeline does not perform any I/O
  60  * and is used to coordinate the dependencies between I/Os that are being
  61  * issued (i.e. the parent/child relationship).
  62  *
  63  * Vdev child Pipeline:
  64  * The vdev child pipeline is responsible for performing the physical I/O.
  65  * It is in this pipeline where the I/O are queued and possibly cached.
  66  *
  67  * In addition to performing I/O, the pipeline is also responsible for
  68  * data transformations. The transformations performed are based on the
  69  * specific properties that user may have selected and modify the
  70  * behavior of the pipeline. Examples of supported transformations are
  71  * compression, dedup, and nop writes. Transformations will either modify
  72  * the data or the pipeline. This list below further describes each of
  73  * the supported transformations:
  74  *
  75  * Compression:
  76  * ZFS supports five different flavors of compression -- gzip, lzjb, lz4, zle,
  77  * and zstd. Compression occurs as part of the write pipeline and is
  78  * performed in the ZIO_STAGE_WRITE_BP_INIT stage.
  79  *
  80  * Block cloning:
  81  * The block cloning functionality introduces ZIO_STAGE_BRT_FREE stage which
  82  * is called during a free pipeline. If the block is referenced in the
  83  * Block Cloning Table (BRT) we will just decrease its reference counter
  84  * instead of actually freeing the block.
  85  *
  86  * Dedup:
  87  * Dedup reads are handled by the ZIO_STAGE_DDT_READ_START and
  88  * ZIO_STAGE_DDT_READ_DONE stages. These stages are added to an existing
  89  * read pipeline if the dedup bit is set on the block pointer.
  90  * Writing a dedup block is performed by the ZIO_STAGE_DDT_WRITE stage
  91  * and added to a write pipeline if a user has enabled dedup on that
  92  * particular dataset.
  93  *
  94  * NOP Write:
  95  * The NOP write feature is performed by the ZIO_STAGE_NOP_WRITE stage
  96  * and is added to an existing write pipeline if a cryptographically
  97  * secure checksum (i.e. SHA256) is enabled and compression is turned on.
  98  * The NOP write stage will compare the checksums of the current data
  99  * on-disk (level-0 blocks only) and the data that is currently being written.
 100  * If the checksum values are identical then the pipeline is converted to
 101  * an interlock pipeline skipping block allocation and bypassing the
 102  * physical I/O.  The nop write feature can handle writes in either
 103  * syncing or open context (i.e. zil writes) and as a result is mutually
 104  * exclusive with dedup.
 105  *
 106  * Encryption:
 107  * Encryption and authentication is handled by the ZIO_STAGE_ENCRYPT stage.
 108  * This stage determines how the encryption metadata is stored in the bp.
 109  * Decryption and MAC verification is performed during zio_decrypt() as a
 110  * transform callback. Encryption is mutually exclusive with nopwrite, because
 111  * blocks with the same plaintext will be encrypted with different salts and
 112  * IV's (if dedup is off), and therefore have different ciphertexts. For dedup
 113  * blocks we deterministically generate the IV and salt by performing an HMAC
 114  * of the plaintext, which is computationally expensive, but allows us to keep
 115  * support for encrypted dedup. See the block comment in zio_crypt.c for
 116  * details.
 117  */
 118
 119 /*
 120  * zio pipeline stage definitions
 121  */
 122 enum zio_stage {
 123         ZIO_STAGE_OPEN                  = 1 << 0,       /* RWFCI */
 124
 125         ZIO_STAGE_READ_BP_INIT          = 1 << 1,       /* R---- */
 126         ZIO_STAGE_WRITE_BP_INIT         = 1 << 2,       /* -W--- */
 127         ZIO_STAGE_FREE_BP_INIT          = 1 << 3,       /* --F-- */
 128         ZIO_STAGE_ISSUE_ASYNC           = 1 << 4,       /* RWF-- */
 129         ZIO_STAGE_WRITE_COMPRESS        = 1 << 5,       /* -W--- */
 130
 131         ZIO_STAGE_ENCRYPT               = 1 << 6,       /* -W--- */
 132         ZIO_STAGE_CHECKSUM_GENERATE     = 1 << 7,       /* -W--- */
 133
 134         ZIO_STAGE_NOP_WRITE             = 1 << 8,       /* -W--- */
 135
 136         ZIO_STAGE_BRT_FREE              = 1 << 9,       /* --F-- */
 137
 138         ZIO_STAGE_DDT_READ_START        = 1 << 10,      /* R---- */
 139         ZIO_STAGE_DDT_READ_DONE         = 1 << 11,      /* R---- */
 140         ZIO_STAGE_DDT_WRITE             = 1 << 12,      /* -W--- */
 141         ZIO_STAGE_DDT_FREE              = 1 << 13,      /* --F-- */
 142
 143         ZIO_STAGE_GANG_ASSEMBLE         = 1 << 14,      /* RWFC- */
 144         ZIO_STAGE_GANG_ISSUE            = 1 << 15,      /* RWFC- */
 145
 146         ZIO_STAGE_DVA_THROTTLE          = 1 << 16,      /* -W--- */
 147         ZIO_STAGE_DVA_ALLOCATE          = 1 << 17,      /* -W--- */
 148         ZIO_STAGE_DVA_FREE              = 1 << 18,      /* --F-- */
 149         ZIO_STAGE_DVA_CLAIM             = 1 << 19,      /* ---C- */
 150
 151         ZIO_STAGE_READY                 = 1 << 20,      /* RWFCI */
 152
 153         ZIO_STAGE_VDEV_IO_START         = 1 << 21,      /* RW--I */
 154         ZIO_STAGE_VDEV_IO_DONE          = 1 << 22,      /* RW--I */
 155         ZIO_STAGE_VDEV_IO_ASSESS        = 1 << 23,      /* RW--I */
 156
 157         ZIO_STAGE_CHECKSUM_VERIFY       = 1 << 24,      /* R---- */
 158
 159         ZIO_STAGE_DONE                  = 1 << 25       /* RWFCI */
 160 };
 161
 162 #define ZIO_INTERLOCK_STAGES                    \
 163         (ZIO_STAGE_READY |                      \
 164         ZIO_STAGE_DONE)
 165
 166 #define ZIO_INTERLOCK_PIPELINE                  \
 167         ZIO_INTERLOCK_STAGES
 168
 169 #define ZIO_VDEV_IO_STAGES                      \
 170         (ZIO_STAGE_VDEV_IO_START |              \
 171         ZIO_STAGE_VDEV_IO_DONE |                \
 172         ZIO_STAGE_VDEV_IO_ASSESS)
 173
 174 #define ZIO_VDEV_CHILD_PIPELINE                 \
 175         (ZIO_VDEV_IO_STAGES |                   \
 176         ZIO_STAGE_DONE)
 177
 178 #define ZIO_READ_COMMON_STAGES                  \
 179         (ZIO_INTERLOCK_STAGES |                 \
 180         ZIO_VDEV_IO_STAGES |                    \
 181         ZIO_STAGE_CHECKSUM_VERIFY)
 182
 183 #define ZIO_READ_PHYS_PIPELINE                  \
 184         ZIO_READ_COMMON_STAGES
 185
 186 #define ZIO_READ_PIPELINE                       \
 187         (ZIO_READ_COMMON_STAGES |               \
 188         ZIO_STAGE_READ_BP_INIT)
 189
 190 #define ZIO_DDT_CHILD_READ_PIPELINE             \
 191         ZIO_READ_COMMON_STAGES
 192
 193 #define ZIO_DDT_READ_PIPELINE                   \
 194         (ZIO_INTERLOCK_STAGES |                 \
 195         ZIO_STAGE_READ_BP_INIT |                \
 196         ZIO_STAGE_DDT_READ_START |              \
 197         ZIO_STAGE_DDT_READ_DONE)
 198
 199 #define ZIO_WRITE_COMMON_STAGES                 \
 200         (ZIO_INTERLOCK_STAGES |                 \
 201         ZIO_VDEV_IO_STAGES |                    \
 202         ZIO_STAGE_ISSUE_ASYNC |                 \
 203         ZIO_STAGE_CHECKSUM_GENERATE)
 204
 205 #define ZIO_WRITE_PHYS_PIPELINE                 \
 206         ZIO_WRITE_COMMON_STAGES
 207
 208 #define ZIO_REWRITE_PIPELINE                    \
 209         (ZIO_WRITE_COMMON_STAGES |              \
 210         ZIO_STAGE_WRITE_COMPRESS |              \
 211         ZIO_STAGE_ENCRYPT |                     \
 212         ZIO_STAGE_WRITE_BP_INIT)
 213
 214 #define ZIO_WRITE_PIPELINE                      \
 215         (ZIO_WRITE_COMMON_STAGES |              \
 216         ZIO_STAGE_WRITE_BP_INIT |               \
 217         ZIO_STAGE_WRITE_COMPRESS |              \
 218         ZIO_STAGE_ENCRYPT |                     \
 219         ZIO_STAGE_DVA_THROTTLE |                \
 220         ZIO_STAGE_DVA_ALLOCATE)
 221
 222 #define ZIO_DDT_CHILD_WRITE_PIPELINE            \
 223         (ZIO_INTERLOCK_STAGES |                 \
 224         ZIO_VDEV_IO_STAGES |                    \
 225         ZIO_STAGE_DVA_THROTTLE |                \
 226         ZIO_STAGE_DVA_ALLOCATE)
 227
 228 #define ZIO_DDT_WRITE_PIPELINE                  \
 229         (ZIO_INTERLOCK_STAGES |                 \
 230         ZIO_STAGE_WRITE_BP_INIT |               \
 231         ZIO_STAGE_ISSUE_ASYNC |                 \
 232         ZIO_STAGE_WRITE_COMPRESS |              \
 233         ZIO_STAGE_ENCRYPT |                     \
 234         ZIO_STAGE_CHECKSUM_GENERATE |           \
 235         ZIO_STAGE_DDT_WRITE)
 236
 237 #define ZIO_GANG_STAGES                         \
 238         (ZIO_STAGE_GANG_ASSEMBLE |              \
 239         ZIO_STAGE_GANG_ISSUE)
 240
 241 #define ZIO_FREE_PIPELINE                       \
 242         (ZIO_INTERLOCK_STAGES |                 \
 243         ZIO_STAGE_FREE_BP_INIT |                \
 244         ZIO_STAGE_BRT_FREE |                    \
 245         ZIO_STAGE_DVA_FREE)
 246
 247 #define ZIO_DDT_FREE_PIPELINE                   \
 248         (ZIO_INTERLOCK_STAGES |                 \
 249         ZIO_STAGE_FREE_BP_INIT |                \
 250         ZIO_STAGE_ISSUE_ASYNC |                 \
 251         ZIO_STAGE_DDT_FREE)
 252
 253 #define ZIO_CLAIM_PIPELINE                      \
 254         (ZIO_INTERLOCK_STAGES |                 \
 255         ZIO_STAGE_DVA_CLAIM)
 256
 257 #define ZIO_IOCTL_PIPELINE                      \
 258         (ZIO_INTERLOCK_STAGES |                 \
 259         ZIO_STAGE_VDEV_IO_START |               \
 260         ZIO_STAGE_VDEV_IO_ASSESS)
 261
 262 #define ZIO_TRIM_PIPELINE                       \
 263         (ZIO_INTERLOCK_STAGES |                 \
 264         ZIO_STAGE_ISSUE_ASYNC |                 \
 265         ZIO_VDEV_IO_STAGES)
 266
 267 #define ZIO_BLOCKING_STAGES                     \
 268         (ZIO_STAGE_DVA_ALLOCATE |               \
 269         ZIO_STAGE_DVA_CLAIM |                   \
 270         ZIO_STAGE_VDEV_IO_START)
 271
 272 extern void zio_inject_init(void);
 273 extern void zio_inject_fini(void);
 274
 275 #ifdef  __cplusplus
 276 }
 277 #endif
 278
 279 #endif  /* _ZIO_IMPL_H */