module/zfs/zio_inject.c

   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 2008 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 /*
  27  * ZFS fault injection
  28  *
  29  * To handle fault injection, we keep track of a series of zinject_record_t
  30  * structures which describe which logical block(s) should be injected with a
  31  * fault.  These are kept in a global list.  Each record corresponds to a given
  32  * spa_t and maintains a special hold on the spa_t so that it cannot be deleted
  33  * or exported while the injection record exists.
  34  *
  35  * Device level injection is done using the 'zi_guid' field.  If this is set, it
  36  * means that the error is destined for a particular device, not a piece of
  37  * data.
  38  *
  39  * This is a rather poor data structure and algorithm, but we don't expect more
  40  * than a few faults at any one time, so it should be sufficient for our needs.
  41  */
  42
  43 #include <sys/arc.h>
  44 #include <sys/zio_impl.h>
  45 #include <sys/zfs_ioctl.h>
  46 #include <sys/spa_impl.h>
  47 #include <sys/vdev_impl.h>
  48 #include <sys/fs/zfs.h>
  49
  50 uint32_t zio_injection_enabled;
  51
  52 typedef struct inject_handler {
  53         int                     zi_id;
  54         spa_t                   *zi_spa;
  55         zinject_record_t        zi_record;
  56         list_node_t             zi_link;
  57 } inject_handler_t;
  58
  59 static list_t inject_handlers;
  60 static krwlock_t inject_lock;
  61 static int inject_next_id = 1;
  62
  63 /*
  64  * Returns true if the given record matches the I/O in progress.
  65  */
  66 static boolean_t
  67 zio_match_handler(zbookmark_t *zb, uint64_t type,
  68     zinject_record_t *record, int error)
  69 {
  70         /*
  71          * Check for a match against the MOS, which is based on type
  72          */
  73         if (zb->zb_objset == 0 && record->zi_objset == 0 &&
  74             record->zi_object == 0) {
  75                 if (record->zi_type == DMU_OT_NONE ||
  76                     type == record->zi_type)
  77                         return (record->zi_freq == 0 ||
  78                             spa_get_random(100) < record->zi_freq);
  79                 else
  80                         return (B_FALSE);
  81         }
  82
  83         /*
  84          * Check for an exact match.
  85          */
  86         if (zb->zb_objset == record->zi_objset &&
  87             zb->zb_object == record->zi_object &&
  88             zb->zb_level == record->zi_level &&
  89             zb->zb_blkid >= record->zi_start &&
  90             zb->zb_blkid <= record->zi_end &&
  91             error == record->zi_error)
  92                 return (record->zi_freq == 0 ||
  93                     spa_get_random(100) < record->zi_freq);
  94
  95         return (B_FALSE);
  96 }
  97
  98 /*
  99  * Determine if the I/O in question should return failure.  Returns the errno
 100  * to be returned to the caller.
 101  */
 102 int
 103 zio_handle_fault_injection(zio_t *zio, int error)
 104 {
 105         int ret = 0;
 106         inject_handler_t *handler;
 107
 108         /*
 109          * Ignore I/O not associated with any logical data.
 110          */
 111         if (zio->io_logical == NULL)
 112                 return (0);
 113
 114         /*
 115          * Currently, we only support fault injection on reads.
 116          */
 117         if (zio->io_type != ZIO_TYPE_READ)
 118                 return (0);
 119
 120         rw_enter(&inject_lock, RW_READER);
 121
 122         for (handler = list_head(&inject_handlers); handler != NULL;
 123             handler = list_next(&inject_handlers, handler)) {
 124
 125                 /* Ignore errors not destined for this pool */
 126                 if (zio->io_spa != handler->zi_spa)
 127                         continue;
 128
 129                 /* Ignore device errors */
 130                 if (handler->zi_record.zi_guid != 0)
 131                         continue;
 132
 133                 /* If this handler matches, return EIO */
 134                 if (zio_match_handler(&zio->io_logical->io_bookmark,
 135                     zio->io_bp ? BP_GET_TYPE(zio->io_bp) : DMU_OT_NONE,
 136                     &handler->zi_record, error)) {
 137                         ret = error;
 138                         break;
 139                 }
 140         }
 141
 142         rw_exit(&inject_lock);
 143
 144         return (ret);
 145 }
 146
 147 /*
 148  * Determine if the zio is part of a label update and has an injection
 149  * handler associated with that portion of the label. Currently, we
 150  * allow error injection in either the nvlist or the uberblock region of
 151  * of the vdev label.
 152  */
 153 int
 154 zio_handle_label_injection(zio_t *zio, int error)
 155 {
 156         inject_handler_t *handler;
 157         vdev_t *vd = zio->io_vd;
 158         uint64_t offset = zio->io_offset;
 159         int label;
 160         int ret = 0;
 161
 162         if (offset + zio->io_size > VDEV_LABEL_START_SIZE &&
 163             offset < vd->vdev_psize - VDEV_LABEL_END_SIZE)
 164                 return (0);
 165
 166         rw_enter(&inject_lock, RW_READER);
 167
 168         for (handler = list_head(&inject_handlers); handler != NULL;
 169             handler = list_next(&inject_handlers, handler)) {
 170                 uint64_t start = handler->zi_record.zi_start;
 171                 uint64_t end = handler->zi_record.zi_end;
 172
 173                 /* Ignore device only faults */
 174                 if (handler->zi_record.zi_start == 0)
 175                         continue;
 176
 177                 /*
 178                  * The injection region is the relative offsets within a
 179                  * vdev label. We must determine the label which is being
 180                  * updated and adjust our region accordingly.
 181                  */
 182                 label = vdev_label_number(vd->vdev_psize, offset);
 183                 start = vdev_label_offset(vd->vdev_psize, label, start);
 184                 end = vdev_label_offset(vd->vdev_psize, label, end);
 185
 186                 if (zio->io_vd->vdev_guid == handler->zi_record.zi_guid &&
 187                     (offset >= start && offset <= end)) {
 188                         ret = error;
 189                         break;
 190                 }
 191         }
 192         rw_exit(&inject_lock);
 193         return (ret);
 194 }
 195
 196
 197 int
 198 zio_handle_device_injection(vdev_t *vd, int error)
 199 {
 200         inject_handler_t *handler;
 201         int ret = 0;
 202
 203         rw_enter(&inject_lock, RW_READER);
 204
 205         for (handler = list_head(&inject_handlers); handler != NULL;
 206             handler = list_next(&inject_handlers, handler)) {
 207
 208                 /* Ignore label specific faults */
 209                 if (handler->zi_record.zi_start != 0)
 210                         continue;
 211
 212                 if (vd->vdev_guid == handler->zi_record.zi_guid) {
 213                         if (handler->zi_record.zi_error == error) {
 214                                 /*
 215                                  * For a failed open, pretend like the device
 216                                  * has gone away.
 217                                  */
 218                                 if (error == ENXIO)
 219                                         vd->vdev_stat.vs_aux =
 220                                             VDEV_AUX_OPEN_FAILED;
 221                                 ret = error;
 222                                 break;
 223                         }
 224                         if (handler->zi_record.zi_error == ENXIO) {
 225                                 ret = EIO;
 226                                 break;
 227                         }
 228                 }
 229         }
 230
 231         rw_exit(&inject_lock);
 232
 233         return (ret);
 234 }
 235
 236 /*
 237  * Create a new handler for the given record.  We add it to the list, adding
 238  * a reference to the spa_t in the process.  We increment zio_injection_enabled,
 239  * which is the switch to trigger all fault injection.
 240  */
 241 int
 242 zio_inject_fault(char *name, int flags, int *id, zinject_record_t *record)
 243 {
 244         inject_handler_t *handler;
 245         int error;
 246         spa_t *spa;
 247
 248         /*
 249          * If this is pool-wide metadata, make sure we unload the corresponding
 250          * spa_t, so that the next attempt to load it will trigger the fault.
 251          * We call spa_reset() to unload the pool appropriately.
 252          */
 253         if (flags & ZINJECT_UNLOAD_SPA)
 254                 if ((error = spa_reset(name)) != 0)
 255                         return (error);
 256
 257         if (!(flags & ZINJECT_NULL)) {
 258                 /*
 259                  * spa_inject_ref() will add an injection reference, which will
 260                  * prevent the pool from being removed from the namespace while
 261                  * still allowing it to be unloaded.
 262                  */
 263                 if ((spa = spa_inject_addref(name)) == NULL)
 264                         return (ENOENT);
 265
 266                 handler = kmem_alloc(sizeof (inject_handler_t), KM_SLEEP);
 267
 268                 rw_enter(&inject_lock, RW_WRITER);
 269
 270                 *id = handler->zi_id = inject_next_id++;
 271                 handler->zi_spa = spa;
 272                 handler->zi_record = *record;
 273                 list_insert_tail(&inject_handlers, handler);
 274                 atomic_add_32(&zio_injection_enabled, 1);
 275
 276                 rw_exit(&inject_lock);
 277         }
 278
 279         /*
 280          * Flush the ARC, so that any attempts to read this data will end up
 281          * going to the ZIO layer.  Note that this is a little overkill, but
 282          * we don't have the necessary ARC interfaces to do anything else, and
 283          * fault injection isn't a performance critical path.
 284          */
 285         if (flags & ZINJECT_FLUSH_ARC)
 286                 arc_flush(NULL);
 287
 288         return (0);
 289 }
 290
 291 /*
 292  * Returns the next record with an ID greater than that supplied to the
 293  * function.  Used to iterate over all handlers in the system.
 294  */
 295 int
 296 zio_inject_list_next(int *id, char *name, size_t buflen,
 297     zinject_record_t *record)
 298 {
 299         inject_handler_t *handler;
 300         int ret;
 301
 302         mutex_enter(&spa_namespace_lock);
 303         rw_enter(&inject_lock, RW_READER);
 304
 305         for (handler = list_head(&inject_handlers); handler != NULL;
 306             handler = list_next(&inject_handlers, handler))
 307                 if (handler->zi_id > *id)
 308                         break;
 309
 310         if (handler) {
 311                 *record = handler->zi_record;
 312                 *id = handler->zi_id;
 313                 (void) strncpy(name, spa_name(handler->zi_spa), buflen);
 314                 ret = 0;
 315         } else {
 316                 ret = ENOENT;
 317         }
 318
 319         rw_exit(&inject_lock);
 320         mutex_exit(&spa_namespace_lock);
 321
 322         return (ret);
 323 }
 324
 325 /*
 326  * Clear the fault handler with the given identifier, or return ENOENT if none
 327  * exists.
 328  */
 329 int
 330 zio_clear_fault(int id)
 331 {
 332         inject_handler_t *handler;
 333         int ret;
 334
 335         rw_enter(&inject_lock, RW_WRITER);
 336
 337         for (handler = list_head(&inject_handlers); handler != NULL;
 338             handler = list_next(&inject_handlers, handler))
 339                 if (handler->zi_id == id)
 340                         break;
 341
 342         if (handler == NULL) {
 343                 ret = ENOENT;
 344         } else {
 345                 list_remove(&inject_handlers, handler);
 346                 spa_inject_delref(handler->zi_spa);
 347                 kmem_free(handler, sizeof (inject_handler_t));
 348                 atomic_add_32(&zio_injection_enabled, -1);
 349                 ret = 0;
 350         }
 351
 352         rw_exit(&inject_lock);
 353
 354         return (ret);
 355 }
 356
 357 void
 358 zio_inject_init(void)
 359 {
 360         rw_init(&inject_lock, NULL, RW_DEFAULT, NULL);
 361         list_create(&inject_handlers, sizeof (inject_handler_t),
 362             offsetof(inject_handler_t, zi_link));
 363 }
 364
 365 void
 366 zio_inject_fini(void)
 367 {
 368         list_destroy(&inject_handlers);
 369         rw_destroy(&inject_lock);
 370 }