zfs/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 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  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 /*
  27  * Copyright (c) 2013 by Delphix. All rights reserved.
  28  */
  29
  30 #ifndef _ZIO_IMPL_H
  31 #define _ZIO_IMPL_H
  32
  33 #include <sys/zfs_context.h>
  34 #include <sys/zio.h>
  35
  36 #ifdef  __cplusplus
  37 extern "C" {
  38 #endif
  39
  40 /*
  41  * XXX -- Describe ZFS I/O pipeline here. Fill in as needed.
  42  *
  43  * The ZFS I/O pipeline is comprised of various stages which are defined
  44  * in the zio_stage enum below. The individual stages are used to construct
  45  * these basic I/O operations: Read, Write, Free, Claim, and Ioctl.
  46  *
  47  * I/O operations: (XXX - provide detail for each of the operations)
  48  *
  49  * Read:
  50  * Write:
  51  * Free:
  52  * Claim:
  53  * Ioctl:
  54  *
  55  * Although the most common pipeline are used by the basic I/O operations
  56  * above, there are some helper pipelines (one could consider them
  57  * sub-pipelines) which are used internally by the ZIO module and are
  58  * explained below:
  59  *
  60  * Interlock Pipeline:
  61  * The interlock pipeline is the most basic pipeline and is used by all
  62  * of the I/O operations. The interlock pipeline does not perform any I/O
  63  * and is used to coordinate the dependencies between I/Os that are being
  64  * issued (i.e. the parent/child relationship).
  65  *
  66  * Vdev child Pipeline:
  67  * The vdev child pipeline is responsible for performing the physical I/O.
  68  * It is in this pipeline where the I/O are queued and possibly cached.
  69  *
  70  * In addition to performing I/O, the pipeline is also responsible for
  71  * data transformations. The transformations performed are based on the
  72  * specific properties that user may have selected and modify the
  73  * behavior of the pipeline. Examples of supported transformations are
  74  * compression, dedup, and nop writes. Transformations will either modify
  75  * the data or the pipeline. This list below further describes each of
  76  * the supported transformations:
  77  *
  78  * Compression:
  79  * ZFS supports three different flavors of compression -- gzip, lzjb, and
  80  * zle. Compression occurs as part of the write pipeline and is performed
  81  * in the ZIO_STAGE_WRITE_BP_INIT stage.
  82  *
  83  * Dedup:
  84  * Dedup reads are handled by the ZIO_STAGE_DDT_READ_START and
  85  * ZIO_STAGE_DDT_READ_DONE stages. These stages are added to an existing
  86  * read pipeline if the dedup bit is set on the block pointer.
  87  * Writing a dedup block is performed by the ZIO_STAGE_DDT_WRITE stage
  88  * and added to a write pipeline if a user has enabled dedup on that
  89  * particular dataset.
  90  *
  91  * NOP Write:
  92  * The NOP write feature is performed by the ZIO_STAGE_NOP_WRITE stage
  93  * and is added to an existing write pipeline if a crypographically
  94  * secure checksum (i.e. SHA256) is enabled and compression is turned on.
  95  * The NOP write stage will compare the checksums of the current data
  96  * on-disk (level-0 blocks only) and the data that is currently being written.
  97  * If the checksum values are identical then the pipeline is converted to
  98  * an interlock pipeline skipping block allocation and bypassing the
  99  * physical I/O.  The nop write feature can handle writes in either
 100  * syncing or open context (i.e. zil writes) and as a result is mutually
 101  * exclusive with dedup.
 102  */
 103
 104 /*
 105  * zio pipeline stage definitions
 106  */
 107 enum zio_stage {
 108         ZIO_STAGE_OPEN                  = 1 << 0,       /* RWFCI */
 109
 110         ZIO_STAGE_READ_BP_INIT          = 1 << 1,       /* R---- */
 111         ZIO_STAGE_FREE_BP_INIT          = 1 << 2,       /* --F-- */
 112         ZIO_STAGE_ISSUE_ASYNC           = 1 << 3,       /* RWF-- */
 113         ZIO_STAGE_WRITE_BP_INIT         = 1 << 4,       /* -W--- */
 114
 115         ZIO_STAGE_CHECKSUM_GENERATE     = 1 << 5,       /* -W--- */
 116
 117         ZIO_STAGE_NOP_WRITE             = 1 << 6,       /* -W--- */
 118
 119         ZIO_STAGE_DDT_READ_START        = 1 << 7,       /* R---- */
 120         ZIO_STAGE_DDT_READ_DONE         = 1 << 8,       /* R---- */
 121         ZIO_STAGE_DDT_WRITE             = 1 << 9,       /* -W--- */
 122         ZIO_STAGE_DDT_FREE              = 1 << 10,      /* --F-- */
 123
 124         ZIO_STAGE_GANG_ASSEMBLE         = 1 << 11,      /* RWFC- */
 125         ZIO_STAGE_GANG_ISSUE            = 1 << 12,      /* RWFC- */
 126
 127         ZIO_STAGE_DVA_ALLOCATE          = 1 << 13,      /* -W--- */
 128         ZIO_STAGE_DVA_FREE              = 1 << 14,      /* --F-- */
 129         ZIO_STAGE_DVA_CLAIM             = 1 << 15,      /* ---C- */
 130
 131         ZIO_STAGE_READY                 = 1 << 16,      /* RWFCI */
 132
 133         ZIO_STAGE_VDEV_IO_START         = 1 << 17,      /* RW--I */
 134         ZIO_STAGE_VDEV_IO_DONE          = 1 << 18,      /* RW--I */
 135         ZIO_STAGE_VDEV_IO_ASSESS        = 1 << 19,      /* RW--I */
 136
 137         ZIO_STAGE_CHECKSUM_VERIFY       = 1 << 20,      /* R---- */
 138
 139         ZIO_STAGE_DONE                  = 1 << 21       /* RWFCI */
 140 };
 141
 142 #define ZIO_INTERLOCK_STAGES                    \
 143         (ZIO_STAGE_READY |                      \
 144         ZIO_STAGE_DONE)
 145
 146 #define ZIO_INTERLOCK_PIPELINE                  \
 147         ZIO_INTERLOCK_STAGES
 148
 149 #define ZIO_VDEV_IO_STAGES                      \
 150         (ZIO_STAGE_VDEV_IO_START |              \
 151         ZIO_STAGE_VDEV_IO_DONE |                \
 152         ZIO_STAGE_VDEV_IO_ASSESS)
 153
 154 #define ZIO_VDEV_CHILD_PIPELINE                 \
 155         (ZIO_VDEV_IO_STAGES |                   \
 156         ZIO_STAGE_DONE)
 157
 158 #define ZIO_READ_COMMON_STAGES                  \
 159         (ZIO_INTERLOCK_STAGES |                 \
 160         ZIO_VDEV_IO_STAGES |                    \
 161         ZIO_STAGE_CHECKSUM_VERIFY)
 162
 163 #define ZIO_READ_PHYS_PIPELINE                  \
 164         ZIO_READ_COMMON_STAGES
 165
 166 #define ZIO_READ_PIPELINE                       \
 167         (ZIO_READ_COMMON_STAGES |               \
 168         ZIO_STAGE_READ_BP_INIT)
 169
 170 #define ZIO_DDT_CHILD_READ_PIPELINE             \
 171         ZIO_READ_COMMON_STAGES
 172
 173 #define ZIO_DDT_READ_PIPELINE                   \
 174         (ZIO_INTERLOCK_STAGES |                 \
 175         ZIO_STAGE_READ_BP_INIT |                \
 176         ZIO_STAGE_DDT_READ_START |              \
 177         ZIO_STAGE_DDT_READ_DONE)
 178
 179 #define ZIO_WRITE_COMMON_STAGES                 \
 180         (ZIO_INTERLOCK_STAGES |                 \
 181         ZIO_VDEV_IO_STAGES |                    \
 182         ZIO_STAGE_ISSUE_ASYNC |                 \
 183         ZIO_STAGE_CHECKSUM_GENERATE)
 184
 185 #define ZIO_WRITE_PHYS_PIPELINE                 \
 186         ZIO_WRITE_COMMON_STAGES
 187
 188 #define ZIO_REWRITE_PIPELINE                    \
 189         (ZIO_WRITE_COMMON_STAGES |              \
 190         ZIO_STAGE_WRITE_BP_INIT)
 191
 192 #define ZIO_WRITE_PIPELINE                      \
 193         (ZIO_WRITE_COMMON_STAGES |              \
 194         ZIO_STAGE_WRITE_BP_INIT |               \
 195         ZIO_STAGE_DVA_ALLOCATE)
 196
 197 #define ZIO_DDT_CHILD_WRITE_PIPELINE            \
 198         (ZIO_INTERLOCK_STAGES |                 \
 199         ZIO_VDEV_IO_STAGES |                    \
 200         ZIO_STAGE_DVA_ALLOCATE)
 201
 202 #define ZIO_DDT_WRITE_PIPELINE                  \
 203         (ZIO_INTERLOCK_STAGES |                 \
 204         ZIO_STAGE_ISSUE_ASYNC |                 \
 205         ZIO_STAGE_WRITE_BP_INIT |               \
 206         ZIO_STAGE_CHECKSUM_GENERATE |           \
 207         ZIO_STAGE_DDT_WRITE)
 208
 209 #define ZIO_GANG_STAGES                         \
 210         (ZIO_STAGE_GANG_ASSEMBLE |              \
 211         ZIO_STAGE_GANG_ISSUE)
 212
 213 #define ZIO_FREE_PIPELINE                       \
 214         (ZIO_INTERLOCK_STAGES |                 \
 215         ZIO_STAGE_FREE_BP_INIT |                \
 216         ZIO_STAGE_DVA_FREE)
 217
 218 #define ZIO_DDT_FREE_PIPELINE                   \
 219         (ZIO_INTERLOCK_STAGES |                 \
 220         ZIO_STAGE_FREE_BP_INIT |                \
 221         ZIO_STAGE_ISSUE_ASYNC |                 \
 222         ZIO_STAGE_DDT_FREE)
 223
 224 #define ZIO_CLAIM_PIPELINE                      \
 225         (ZIO_INTERLOCK_STAGES |                 \
 226         ZIO_STAGE_DVA_CLAIM)
 227
 228 #define ZIO_IOCTL_PIPELINE                      \
 229         (ZIO_INTERLOCK_STAGES |                 \
 230         ZIO_STAGE_VDEV_IO_START |               \
 231         ZIO_STAGE_VDEV_IO_ASSESS)
 232
 233 #define ZIO_BLOCKING_STAGES                     \
 234         (ZIO_STAGE_DVA_ALLOCATE |               \
 235         ZIO_STAGE_DVA_CLAIM |                   \
 236         ZIO_STAGE_VDEV_IO_START)
 237
 238 extern void zio_inject_init(void);
 239 extern void zio_inject_fini(void);
 240
 241 #ifdef  __cplusplus
 242 }
 243 #endif
 244
 245 #endif  /* _ZIO_IMPL_H */