sys/vfs/hammer/hammer_prune.c

   1 /*
   2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/vfs/hammer/hammer_prune.c,v 1.8 2008/06/26 04:06:23 dillon Exp $
  35  */
  36
  37 #include "hammer.h"
  38
  39 /*
  40  * Iterate through the specified range of object ids and remove any
  41  * deleted records that fall entirely within a prune modulo.
  42  *
  43  * A reverse iteration is used to prevent overlapping records from being
  44  * created during the iteration due to alignments.  This also allows us
  45  * to adjust alignments without blowing up the B-Tree.
  46  */
  47 static int check_prune(struct hammer_ioc_prune *prune, hammer_btree_elm_t elm);
  48
  49 int
  50 hammer_ioc_prune(hammer_transaction_t trans, hammer_inode_t ip,
  51                  struct hammer_ioc_prune *prune)
  52 {
  53         struct hammer_cursor cursor;
  54         hammer_btree_elm_t elm;
  55         struct hammer_ioc_prune_elm *copy_elms;
  56         struct hammer_ioc_prune_elm *user_elms;
  57         int error;
  58         int isdir;
  59         int elm_array_size;
  60
  61         if (prune->nelms < 0 || prune->nelms > HAMMER_MAX_PRUNE_ELMS)
  62                 return(EINVAL);
  63         if ((prune->key_beg.localization | prune->key_end.localization) &
  64             HAMMER_LOCALIZE_PSEUDOFS_MASK) {
  65                 return(EINVAL);
  66         }
  67         if (prune->key_beg.localization > prune->key_end.localization)
  68                 return(EINVAL);
  69         if (prune->key_beg.localization == prune->key_end.localization) {
  70                 if (prune->key_beg.obj_id > prune->key_end.obj_id)
  71                         return(EINVAL);
  72                 /* key-space limitations - no check needed */
  73         }
  74         if ((prune->head.flags & HAMMER_IOC_PRUNE_ALL) && prune->nelms)
  75                 return(EINVAL);
  76
  77         prune->key_cur.localization = prune->key_end.localization +
  78                                       ip->obj_localization;
  79         prune->key_cur.obj_id = prune->key_end.obj_id;
  80         prune->key_cur.key = HAMMER_MAX_KEY;
  81
  82         /*
  83          * Copy element array from userland
  84          */
  85         elm_array_size = sizeof(*copy_elms) * prune->nelms;
  86         user_elms = prune->elms;
  87         copy_elms = kmalloc(elm_array_size, M_TEMP, M_WAITOK);
  88         if ((error = copyin(user_elms, copy_elms, elm_array_size)) != 0)
  89                 goto failed;
  90         prune->elms = copy_elms;
  91
  92         /*
  93          * Scan backwards.  Retries typically occur if a deadlock is detected.
  94          */
  95 retry:
  96         error = hammer_init_cursor(trans, &cursor, NULL, NULL);
  97         if (error) {
  98                 hammer_done_cursor(&cursor);
  99                 goto failed;
 100         }
 101         cursor.key_beg.localization = prune->key_beg.localization +
 102                                       ip->obj_localization;
 103         cursor.key_beg.obj_id = prune->key_beg.obj_id;
 104         cursor.key_beg.key = HAMMER_MIN_KEY;
 105         cursor.key_beg.create_tid = 1;
 106         cursor.key_beg.delete_tid = 0;
 107         cursor.key_beg.rec_type = HAMMER_MIN_RECTYPE;
 108         cursor.key_beg.obj_type = 0;
 109
 110         cursor.key_end.localization = prune->key_cur.localization;
 111         cursor.key_end.obj_id = prune->key_cur.obj_id;
 112         cursor.key_end.key = prune->key_cur.key;
 113         cursor.key_end.create_tid = HAMMER_MAX_TID - 1;
 114         cursor.key_end.delete_tid = 0;
 115         cursor.key_end.rec_type = HAMMER_MAX_RECTYPE;
 116         cursor.key_end.obj_type = 0;
 117
 118         cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE;
 119         cursor.flags |= HAMMER_CURSOR_BACKEND;
 120
 121         /*
 122          * This flag allows the B-Tree code to clean up loose ends.
 123          */
 124         cursor.flags |= HAMMER_CURSOR_PRUNING;
 125
 126         hammer_sync_lock_sh(trans);
 127         error = hammer_btree_last(&cursor);
 128
 129         while (error == 0) {
 130                 /*
 131                  * Yield to more important tasks
 132                  */
 133                 if ((error = hammer_signal_check(trans->hmp)) != 0)
 134                         break;
 135                 if (trans->hmp->sync_lock.wanted) {
 136                         hammer_sync_unlock(trans);
 137                         tsleep(trans, 0, "hmrslo", hz / 10);
 138                         hammer_sync_lock_sh(trans);
 139                 }
 140                 if (trans->hmp->locked_dirty_count +
 141                     trans->hmp->io_running_count > hammer_limit_dirtybufs) {
 142                         hammer_sync_unlock(trans);
 143                         hammer_flusher_async(trans->hmp);
 144                         tsleep(trans, 0, "hmrslo", hz / 10);
 145                         hammer_sync_lock_sh(trans);
 146                 }
 147
 148                 /*
 149                  * Check for work
 150                  */
 151                 elm = &cursor.node->ondisk->elms[cursor.index];
 152                 prune->key_cur = elm->base;
 153
 154                 if (prune->stat_oldest_tid > elm->leaf.base.create_tid)
 155                         prune->stat_oldest_tid = elm->leaf.base.create_tid;
 156
 157                 if (hammer_debug_general & 0x0200) {
 158                         kprintf("check %016llx %016llx cre=%016llx del=%016llx\n",
 159                                         elm->base.obj_id,
 160                                         elm->base.key,
 161                                         elm->base.create_tid,
 162                                         elm->base.delete_tid);
 163                 }
 164
 165                 if (check_prune(prune, elm) == 0) {
 166                         if (hammer_debug_general & 0x0200) {
 167                                 kprintf("check %016llx %016llx: DELETE\n",
 168                                         elm->base.obj_id, elm->base.key);
 169                         }
 170
 171                         /*
 172                          * NOTE: This can return EDEADLK
 173                          *
 174                          * Acquiring the sync lock guarantees that the
 175                          * operation will not cross a synchronization
 176                          * boundary (see the flusher).
 177                          */
 178                         isdir = (elm->base.rec_type == HAMMER_RECTYPE_DIRENTRY);
 179
 180                         error = hammer_delete_at_cursor(&cursor,
 181                                                         &prune->stat_bytes);
 182                         if (error)
 183                                 break;
 184
 185                         if (isdir)
 186                                 ++prune->stat_dirrecords;
 187                         else
 188                                 ++prune->stat_rawrecords;
 189
 190                         /*
 191                          * The current record might now be the one after
 192                          * the one we deleted, set ATEDISK to force us
 193                          * to skip it (since we are iterating backwards).
 194                          */
 195                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 196                 } else {
 197                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 198                         if (hammer_debug_general & 0x0100) {
 199                                 kprintf("check %016llx %016llx: SKIP\n",
 200                                         elm->base.obj_id, elm->base.key);
 201                         }
 202                 }
 203                 ++prune->stat_scanrecords;
 204                 error = hammer_btree_iterate_reverse(&cursor);
 205         }
 206         hammer_sync_unlock(trans);
 207         if (error == ENOENT)
 208                 error = 0;
 209         hammer_done_cursor(&cursor);
 210         if (error == EDEADLK)
 211                 goto retry;
 212         if (error == EINTR) {
 213                 prune->head.flags |= HAMMER_IOC_HEAD_INTR;
 214                 error = 0;
 215         }
 216 failed:
 217         prune->key_cur.localization &= HAMMER_LOCALIZE_MASK;
 218         prune->elms = user_elms;
 219         kfree(copy_elms, M_TEMP);
 220         return(error);
 221 }
 222
 223 /*
 224  * Check pruning list.  The list must be sorted in descending order.
 225  */
 226 static int
 227 check_prune(struct hammer_ioc_prune *prune, hammer_btree_elm_t elm)
 228 {
 229         struct hammer_ioc_prune_elm *scan;
 230         int i;
 231
 232         /*
 233          * If pruning everything remove all records with a non-zero
 234          * delete_tid.
 235          */
 236         if (prune->head.flags & HAMMER_IOC_PRUNE_ALL) {
 237                 if (elm->base.delete_tid != 0)
 238                         return(0);
 239                 return(-1);
 240         }
 241
 242         for (i = 0; i < prune->nelms; ++i) {
 243                 scan = &prune->elms[i];
 244
 245 #if 0
 246                 /*
 247                  * Locate the scan index covering the create and delete TIDs.
 248                  */
 249                 if (*realign_cre < 0 &&
 250                     elm->base.create_tid >= scan->beg_tid &&
 251                     elm->base.create_tid < scan->end_tid) {
 252                         *realign_cre = i;
 253                 }
 254                 if (*realign_del < 0 && elm->base.delete_tid &&
 255                     elm->base.delete_tid > scan->beg_tid &&
 256                     elm->base.delete_tid <= scan->end_tid) {
 257                         *realign_del = i;
 258                 }
 259 #endif
 260
 261                 /*
 262                  * Now check for loop termination.
 263                  */
 264                 if (elm->base.create_tid >= scan->end_tid ||
 265                     elm->base.delete_tid > scan->end_tid) {
 266                         break;
 267                 }
 268
 269                 /*
 270                  * Now determine if we can delete the record.
 271                  */
 272                 if (elm->base.delete_tid &&
 273                     elm->base.create_tid >= scan->beg_tid &&
 274                     elm->base.delete_tid <= scan->end_tid &&
 275                     (elm->base.create_tid - scan->beg_tid) / scan->mod_tid ==
 276                     (elm->base.delete_tid - scan->beg_tid) / scan->mod_tid) {
 277                         return(0);
 278                 }
 279         }
 280         return(-1);
 281 }
 282
 283 #if 0
 284
 285 /*
 286  * NOTE: THIS CODE HAS BEEN REMOVED!  Pruning no longer attempts to realign
 287  *       adjacent records because it seriously interferes with every
 288  *       mirroring algorithm I could come up with.
 289  *
 290  *       This means that historical accesses beyond the first snapshot
 291  *       softlink should be on snapshot boundaries only.  Historical
 292  *       accesses from "now" to the first snapshot softlink continue to
 293  *       be fine-grained.
 294  *
 295  * Align the record to cover any gaps created through the deletion of
 296  * records within the pruning space.  If we were to just delete the records
 297  * there would be gaps which in turn would cause a snapshot that is NOT on
 298  * a pruning boundary to appear corrupt to the user.  Forcing alignment
 299  * of the create_tid and delete_tid for retained records 'reconnects'
 300  * the previously contiguous space, making it contiguous again after the
 301  * deletions.
 302  *
 303  * The use of a reverse iteration allows us to safely align the records and
 304  * related elements without creating temporary overlaps.  XXX we should
 305  * add ordering dependancies for record buffers to guarantee consistency
 306  * during recovery.
 307  */
 308 static int
 309 realign_prune(struct hammer_ioc_prune *prune,
 310               hammer_cursor_t cursor, int realign_cre, int realign_del)
 311 {
 312         struct hammer_ioc_prune_elm *scan;
 313         hammer_btree_elm_t elm;
 314         hammer_tid_t delta;
 315         hammer_tid_t tid;
 316         int error;
 317
 318         hammer_cursor_downgrade(cursor);
 319
 320         elm = &cursor->node->ondisk->elms[cursor->index];
 321         ++prune->stat_realignments;
 322
 323         /*
 324          * Align the create_tid.  By doing a reverse iteration we guarantee
 325          * that all records after our current record have already been
 326          * aligned, allowing us to safely correct the right-hand-boundary
 327          * (because no record to our right is otherwise exactly matching
 328          * will have a create_tid to the left of our aligned create_tid).
 329          */
 330         error = 0;
 331         if (realign_cre >= 0) {
 332                 scan = &prune->elms[realign_cre];
 333
 334                 delta = (elm->leaf.base.create_tid - scan->beg_tid) %
 335                         scan->mod_tid;
 336                 if (delta) {
 337                         tid = elm->leaf.base.create_tid - delta + scan->mod_tid;
 338
 339                         /* can EDEADLK */
 340                         error = hammer_btree_correct_rhb(cursor, tid + 1);
 341                         if (error == 0) {
 342                                 error = hammer_btree_extract(cursor,
 343                                                      HAMMER_CURSOR_GET_LEAF);
 344                         }
 345                         if (error == 0) {
 346                                 /* can EDEADLK */
 347                                 error = hammer_cursor_upgrade(cursor);
 348                         }
 349                         if (error == 0) {
 350                                 hammer_modify_node(cursor->trans, cursor->node,
 351                                             &elm->leaf.base.create_tid,
 352                                             sizeof(elm->leaf.base.create_tid));
 353                                 elm->leaf.base.create_tid = tid;
 354                                 hammer_modify_node_done(cursor->node);
 355                         }
 356                 }
 357         }
 358
 359         /*
 360          * Align the delete_tid.  This only occurs if the record is historical
 361          * was deleted at some point.  Realigning the delete_tid does not
 362          * move the record within the B-Tree but may cause it to temporarily
 363          * overlap a record that has not yet been pruned.
 364          */
 365         if (error == 0 && realign_del >= 0) {
 366                 scan = &prune->elms[realign_del];
 367
 368                 delta = (elm->leaf.base.delete_tid - scan->beg_tid) %
 369                         scan->mod_tid;
 370                 if (delta) {
 371                         error = hammer_btree_extract(cursor,
 372                                                      HAMMER_CURSOR_GET_LEAF);
 373                         if (error == 0) {
 374                                 hammer_modify_node(cursor->trans, cursor->node,
 375                                             &elm->leaf.base.delete_tid,
 376                                             sizeof(elm->leaf.base.delete_tid));
 377                                 elm->leaf.base.delete_tid =
 378                                             elm->leaf.base.delete_tid -
 379                                             delta + scan->mod_tid;
 380                                 hammer_modify_node_done(cursor->node);
 381                         }
 382                 }
 383         }
 384         return (error);
 385 }
 386
 387 #endif