sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_history.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 /*
  23  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include <sys/spa_impl.h>
  30 #include <sys/zap.h>
  31 #include <sys/dsl_synctask.h>
  32
  33 /*
  34  * Routines to manage the on-disk history log.
  35  *
  36  * The history log is stored as a dmu object containing
  37  * <packed record length, record nvlist> tuples.
  38  *
  39  * Where "record nvlist" is a nvlist containing uint64_ts and strings, and
  40  * "packed record length" is the packed length of the "record nvlist" stored
  41  * as a little endian uint64_t.
  42  *
  43  * The log is implemented as a ring buffer, though the original creation
  44  * of the pool ('zpool create') is never overwritten.
  45  *
  46  * The history log is tracked as object 'spa_t::spa_history'.  The bonus buffer
  47  * of 'spa_history' stores the offsets for logging/retrieving history as
  48  * 'spa_history_phys_t'.  'sh_pool_create_len' is the ending offset in bytes of
  49  * where the 'zpool create' record is stored.  This allows us to never
  50  * overwrite the original creation of the pool.  'sh_phys_max_off' is the
  51  * physical ending offset in bytes of the log.  This tells you the length of
  52  * the buffer. 'sh_eof' is the logical EOF (in bytes).  Whenever a record
  53  * is added, 'sh_eof' is incremented by the the size of the record.
  54  * 'sh_eof' is never decremented.  'sh_bof' is the logical BOF (in bytes).
  55  * This is where the consumer should start reading from after reading in
  56  * the 'zpool create' portion of the log.
  57  *
  58  * 'sh_records_lost' keeps track of how many records have been overwritten
  59  * and permanently lost.
  60  */
  61
  62 typedef enum history_log_type {
  63         LOG_CMD_CREATE,
  64         LOG_CMD_NO_CREATE
  65 } history_log_type_t;
  66
  67 typedef struct history_arg {
  68         const char *ha_history_str;
  69         history_log_type_t ha_log_type;
  70 } history_arg_t;
  71
  72 /* convert a logical offset to physical */
  73 static uint64_t
  74 spa_history_log_to_phys(uint64_t log_off, spa_history_phys_t *shpp)
  75 {
  76         uint64_t phys_len;
  77
  78         phys_len = shpp->sh_phys_max_off - shpp->sh_pool_create_len;
  79         return ((log_off - shpp->sh_pool_create_len) % phys_len
  80             + shpp->sh_pool_create_len);
  81 }
  82
  83 void
  84 spa_history_create_obj(spa_t *spa, dmu_tx_t *tx)
  85 {
  86         dmu_buf_t *dbp;
  87         spa_history_phys_t *shpp;
  88         objset_t *mos = spa->spa_meta_objset;
  89
  90         ASSERT(spa->spa_history == 0);
  91         spa->spa_history = dmu_object_alloc(mos, DMU_OT_SPA_HISTORY,
  92             SPA_MAXBLOCKSIZE, DMU_OT_SPA_HISTORY_OFFSETS,
  93             sizeof (spa_history_phys_t), tx);
  94
  95         VERIFY(zap_add(mos, DMU_POOL_DIRECTORY_OBJECT,
  96             DMU_POOL_HISTORY, sizeof (uint64_t), 1,
  97             &spa->spa_history, tx) == 0);
  98
  99         VERIFY(0 == dmu_bonus_hold(mos, spa->spa_history, FTAG, &dbp));
 100         ASSERT(dbp->db_size >= sizeof (spa_history_phys_t));
 101
 102         shpp = dbp->db_data;
 103         dmu_buf_will_dirty(dbp, tx);
 104
 105         /*
 106          * Figure out maximum size of history log.  We set it at
 107          * 1% of pool size, with a max of 32MB and min of 128KB.
 108          */
 109         shpp->sh_phys_max_off = spa_get_dspace(spa) / 100;
 110         shpp->sh_phys_max_off = MIN(shpp->sh_phys_max_off, 32<<20);
 111         shpp->sh_phys_max_off = MAX(shpp->sh_phys_max_off, 128<<10);
 112
 113         dmu_buf_rele(dbp, FTAG);
 114 }
 115
 116 /*
 117  * Change 'sh_bof' to the beginning of the next record.
 118  */
 119 static int
 120 spa_history_advance_bof(spa_t *spa, spa_history_phys_t *shpp)
 121 {
 122         objset_t *mos = spa->spa_meta_objset;
 123         uint64_t firstread, reclen, phys_bof;
 124         char buf[sizeof (reclen)];
 125         int err;
 126
 127         phys_bof = spa_history_log_to_phys(shpp->sh_bof, shpp);
 128         firstread = MIN(sizeof (reclen), shpp->sh_phys_max_off - phys_bof);
 129
 130         if ((err = dmu_read(mos, spa->spa_history, phys_bof, firstread,
 131             buf)) != 0)
 132                 return (err);
 133         if (firstread != sizeof (reclen)) {
 134                 if ((err = dmu_read(mos, spa->spa_history,
 135                     shpp->sh_pool_create_len, sizeof (reclen) - firstread,
 136                     buf + firstread)) != 0)
 137                         return (err);
 138         }
 139
 140         reclen = LE_64(*((uint64_t *)buf));
 141         shpp->sh_bof += reclen + sizeof (reclen);
 142         shpp->sh_records_lost++;
 143         return (0);
 144 }
 145
 146 static int
 147 spa_history_write(spa_t *spa, void *buf, uint64_t len, spa_history_phys_t *shpp,
 148     dmu_tx_t *tx)
 149 {
 150         uint64_t firstwrite, phys_eof;
 151         objset_t *mos = spa->spa_meta_objset;
 152         int err;
 153
 154         ASSERT(MUTEX_HELD(&spa->spa_history_lock));
 155
 156         /* see if we need to reset logical BOF */
 157         while (shpp->sh_phys_max_off - shpp->sh_pool_create_len -
 158             (shpp->sh_eof - shpp->sh_bof) <= len) {
 159                 if ((err = spa_history_advance_bof(spa, shpp)) != 0)
 160                         return (err);
 161         }
 162
 163         phys_eof = spa_history_log_to_phys(shpp->sh_eof, shpp);
 164         firstwrite = MIN(len, shpp->sh_phys_max_off - phys_eof);
 165         shpp->sh_eof += len;
 166         dmu_write(mos, spa->spa_history, phys_eof, firstwrite, buf, tx);
 167
 168         len -= firstwrite;
 169         if (len > 0) {
 170                 /* write out the rest at the beginning of physical file */
 171                 dmu_write(mos, spa->spa_history, shpp->sh_pool_create_len,
 172                     len, (char *)buf + firstwrite, tx);
 173         }
 174
 175         return (0);
 176 }
 177
 178 /*
 179  * Write out a history event.
 180  */
 181 void
 182 spa_history_log_sync(void *arg1, void *arg2, dmu_tx_t *tx)
 183 {
 184         spa_t           *spa = arg1;
 185         history_arg_t   *hap = arg2;
 186         const char      *history_str = hap->ha_history_str;
 187         objset_t        *mos = spa->spa_meta_objset;
 188         dmu_buf_t       *dbp;
 189         spa_history_phys_t *shpp;
 190         size_t          reclen;
 191         uint64_t        le_len;
 192         nvlist_t        *nvrecord;
 193         char            *record_packed = NULL;
 194         int             ret;
 195
 196         if (history_str == NULL)
 197                 return;
 198
 199         /*
 200          * If we have an older pool that doesn't have a command
 201          * history object, create it now.
 202          */
 203         mutex_enter(&spa->spa_history_lock);
 204         if (!spa->spa_history)
 205                 spa_history_create_obj(spa, tx);
 206         mutex_exit(&spa->spa_history_lock);
 207
 208         /*
 209          * Get the offset of where we need to write via the bonus buffer.
 210          * Update the offset when the write completes.
 211          */
 212         VERIFY(0 == dmu_bonus_hold(mos, spa->spa_history, FTAG, &dbp));
 213         shpp = dbp->db_data;
 214
 215         dmu_buf_will_dirty(dbp, tx);
 216
 217 #ifdef ZFS_DEBUG
 218         {
 219                 dmu_object_info_t doi;
 220                 dmu_object_info_from_db(dbp, &doi);
 221                 ASSERT3U(doi.doi_bonus_type, ==, DMU_OT_SPA_HISTORY_OFFSETS);
 222         }
 223 #endif
 224
 225         /* construct a nvlist of the current time and cmd string */
 226         VERIFY(nvlist_alloc(&nvrecord, NV_UNIQUE_NAME, KM_SLEEP) == 0);
 227         VERIFY(nvlist_add_uint64(nvrecord, ZPOOL_HIST_TIME,
 228             gethrestime_sec()) == 0);
 229         VERIFY(nvlist_add_string(nvrecord, ZPOOL_HIST_CMD, history_str) == 0);
 230         VERIFY(nvlist_pack(nvrecord, &record_packed, &reclen,
 231             NV_ENCODE_XDR, KM_SLEEP) == 0);
 232
 233         mutex_enter(&spa->spa_history_lock);
 234         if (hap->ha_log_type == LOG_CMD_CREATE)
 235                 VERIFY(shpp->sh_eof == shpp->sh_pool_create_len);
 236
 237         /* write out the packed length as little endian */
 238         le_len = LE_64((uint64_t)reclen);
 239         ret = spa_history_write(spa, &le_len, sizeof (le_len), shpp, tx);
 240         if (!ret)
 241                 ret = spa_history_write(spa, record_packed, reclen, shpp, tx);
 242
 243         if (!ret && hap->ha_log_type == LOG_CMD_CREATE) {
 244                 shpp->sh_pool_create_len += sizeof (le_len) + reclen;
 245                 shpp->sh_bof = shpp->sh_pool_create_len;
 246         }
 247
 248         mutex_exit(&spa->spa_history_lock);
 249         nvlist_free(nvrecord);
 250         kmem_free(record_packed, reclen);
 251         dmu_buf_rele(dbp, FTAG);
 252 }
 253
 254 /*
 255  * Write out a history event.
 256  */
 257 int
 258 spa_history_log(spa_t *spa, const char *history_str, uint64_t pool_create)
 259 {
 260         history_arg_t ha;
 261
 262         ha.ha_history_str = history_str;
 263         ha.ha_log_type = pool_create ? LOG_CMD_CREATE : LOG_CMD_NO_CREATE;
 264         return (dsl_sync_task_do(spa_get_dsl(spa), NULL, spa_history_log_sync,
 265             spa, &ha, 0));
 266 }
 267
 268 /*
 269  * Read out the command history.
 270  */
 271 int
 272 spa_history_get(spa_t *spa, uint64_t *offp, uint64_t *len, char *buf)
 273 {
 274         objset_t *mos = spa->spa_meta_objset;
 275         dmu_buf_t *dbp;
 276         uint64_t read_len, phys_read_off, phys_eof;
 277         uint64_t leftover = 0;
 278         spa_history_phys_t *shpp;
 279         int err;
 280
 281         /*
 282          * If the command history  doesn't exist (older pool),
 283          * that's ok, just return ENOENT.
 284          */
 285         if (!spa->spa_history)
 286                 return (ENOENT);
 287
 288         if ((err = dmu_bonus_hold(mos, spa->spa_history, FTAG, &dbp)) != 0)
 289                 return (err);
 290         shpp = dbp->db_data;
 291
 292 #ifdef ZFS_DEBUG
 293         {
 294                 dmu_object_info_t doi;
 295                 dmu_object_info_from_db(dbp, &doi);
 296                 ASSERT3U(doi.doi_bonus_type, ==, DMU_OT_SPA_HISTORY_OFFSETS);
 297         }
 298 #endif
 299
 300         mutex_enter(&spa->spa_history_lock);
 301         phys_eof = spa_history_log_to_phys(shpp->sh_eof, shpp);
 302
 303         if (*offp < shpp->sh_pool_create_len) {
 304                 /* read in just the zpool create history */
 305                 phys_read_off = *offp;
 306                 read_len = MIN(*len, shpp->sh_pool_create_len -
 307                     phys_read_off);
 308         } else {
 309                 /*
 310                  * Need to reset passed in offset to BOF if the passed in
 311                  * offset has since been overwritten.
 312                  */
 313                 *offp = MAX(*offp, shpp->sh_bof);
 314                 phys_read_off = spa_history_log_to_phys(*offp, shpp);
 315
 316                 /*
 317                  * Read up to the minimum of what the user passed down or
 318                  * the EOF (physical or logical).  If we hit physical EOF,
 319                  * use 'leftover' to read from the physical BOF.
 320                  */
 321                 if (phys_read_off <= phys_eof) {
 322                         read_len = MIN(*len, phys_eof - phys_read_off);
 323                 } else {
 324                         read_len = MIN(*len,
 325                             shpp->sh_phys_max_off - phys_read_off);
 326                         if (phys_read_off + *len > shpp->sh_phys_max_off) {
 327                                 leftover = MIN(*len - read_len,
 328                                     phys_eof - shpp->sh_pool_create_len);
 329                         }
 330                 }
 331         }
 332
 333         /* offset for consumer to use next */
 334         *offp += read_len + leftover;
 335
 336         /* tell the consumer how much you actually read */
 337         *len = read_len + leftover;
 338
 339         if (read_len == 0) {
 340                 mutex_exit(&spa->spa_history_lock);
 341                 dmu_buf_rele(dbp, FTAG);
 342                 return (0);
 343         }
 344
 345         err = dmu_read(mos, spa->spa_history, phys_read_off, read_len, buf);
 346         if (leftover && err == 0) {
 347                 err = dmu_read(mos, spa->spa_history, shpp->sh_pool_create_len,
 348                     leftover, buf + read_len);
 349         }
 350         mutex_exit(&spa->spa_history_lock);
 351
 352         dmu_buf_rele(dbp, FTAG);
 353         return (err);
 354 }