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 1.4 2008/06/01 01:33:25 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                         int *realign_cre, int *realign_del);
  49 static int realign_prune(struct hammer_ioc_prune *prune, hammer_cursor_t cursor,
  50                         int realign_cre, int realign_del);
  51
  52 int
  53 hammer_ioc_prune(hammer_transaction_t trans, hammer_inode_t ip,
  54                  struct hammer_ioc_prune *prune)
  55 {
  56         struct hammer_cursor cursor;
  57         hammer_btree_elm_t elm;
  58         struct hammer_ioc_prune_elm *copy_elms;
  59         struct hammer_ioc_prune_elm *user_elms;
  60         int error;
  61         int isdir;
  62         int realign_cre;
  63         int realign_del;
  64         int elm_array_size;
  65
  66         if (prune->nelms < 0 || prune->nelms > HAMMER_MAX_PRUNE_ELMS)
  67                 return(EINVAL);
  68         if (prune->beg_localization > prune->end_localization)
  69                 return(EINVAL);
  70         if (prune->beg_localization == prune->end_localization) {
  71                 if (prune->beg_obj_id > prune->end_obj_id)
  72                         return(EINVAL);
  73                 /* key-space limitations - no check needed */
  74         }
  75         if ((prune->head.flags & HAMMER_IOC_PRUNE_ALL) && prune->nelms)
  76                 return(EINVAL);
  77
  78         prune->cur_localization = prune->end_localization;
  79         prune->cur_obj_id = prune->end_obj_id;
  80         prune->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->beg_localization;
 102         cursor.key_beg.obj_id = prune->beg_obj_id;
 103         cursor.key_beg.key = HAMMER_MIN_KEY;
 104         cursor.key_beg.create_tid = 1;
 105         cursor.key_beg.delete_tid = 0;
 106         cursor.key_beg.rec_type = HAMMER_MIN_RECTYPE;
 107         cursor.key_beg.obj_type = 0;
 108
 109         cursor.key_end.localization = prune->cur_localization;
 110         cursor.key_end.obj_id = prune->cur_obj_id;
 111         cursor.key_end.key = prune->cur_key;
 112         cursor.key_end.create_tid = HAMMER_MAX_TID - 1;
 113         cursor.key_end.delete_tid = 0;
 114         cursor.key_end.rec_type = HAMMER_MAX_RECTYPE;
 115         cursor.key_end.obj_type = 0;
 116
 117         cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE;
 118         cursor.flags |= HAMMER_CURSOR_BACKEND;
 119
 120         /*
 121          * This flag allows the B-Tree code to clean up loose ends.
 122          */
 123         cursor.flags |= HAMMER_CURSOR_PRUNING;
 124
 125         hammer_sync_lock_sh(trans);
 126         error = hammer_btree_last(&cursor);
 127         while (error == 0) {
 128                 /*
 129                  * Yield to more important tasks
 130                  */
 131                 if (trans->hmp->sync_lock.wanted) {
 132                         hammer_sync_unlock(trans);
 133                         tsleep(trans, 0, "hmrslo", hz / 10);
 134                         hammer_sync_lock_sh(trans);
 135                 }
 136
 137                 /*
 138                  * Check for work
 139                  */
 140                 elm = &cursor.node->ondisk->elms[cursor.index];
 141                 prune->cur_localization = elm->base.localization;
 142                 prune->cur_obj_id = elm->base.obj_id;
 143                 prune->cur_key = elm->base.key;
 144
 145                 if (prune->stat_oldest_tid > elm->leaf.base.create_tid)
 146                         prune->stat_oldest_tid = elm->leaf.base.create_tid;
 147
 148                 if (hammer_debug_general & 0x0200) {
 149                         kprintf("check %016llx %016llx cre=%016llx del=%016llx\n",
 150                                         elm->base.obj_id,
 151                                         elm->base.key,
 152                                         elm->base.create_tid,
 153                                         elm->base.delete_tid);
 154                 }
 155
 156                 if (check_prune(prune, elm, &realign_cre, &realign_del) == 0) {
 157                         if (hammer_debug_general & 0x0200) {
 158                                 kprintf("check %016llx %016llx: DELETE\n",
 159                                         elm->base.obj_id, elm->base.key);
 160                         }
 161
 162                         /*
 163                          * NOTE: This can return EDEADLK
 164                          *
 165                          * Acquiring the sync lock guarantees that the
 166                          * operation will not cross a synchronization
 167                          * boundary (see the flusher).
 168                          */
 169                         isdir = (elm->base.rec_type == HAMMER_RECTYPE_DIRENTRY);
 170
 171                         error = hammer_delete_at_cursor(&cursor,
 172                                                         &prune->stat_bytes);
 173                         if (error)
 174                                 break;
 175
 176                         if (isdir)
 177                                 ++prune->stat_dirrecords;
 178                         else
 179                                 ++prune->stat_rawrecords;
 180
 181                         /*
 182                          * The current record might now be the one after
 183                          * the one we deleted, set ATEDISK to force us
 184                          * to skip it (since we are iterating backwards).
 185                          */
 186                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 187                 } else if (realign_cre >= 0 || realign_del >= 0) {
 188                         error = realign_prune(prune, &cursor,
 189                                               realign_cre, realign_del);
 190                         if (error == 0) {
 191                                 cursor.flags |= HAMMER_CURSOR_ATEDISK;
 192                                 if (hammer_debug_general & 0x0200) {
 193                                         kprintf("check %016llx %016llx: "
 194                                                 "REALIGN\n",
 195                                                 elm->base.obj_id,
 196                                                 elm->base.key);
 197                                 }
 198                         }
 199                 } else {
 200                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 201                         if (hammer_debug_general & 0x0100) {
 202                                 kprintf("check %016llx %016llx: SKIP\n",
 203                                         elm->base.obj_id, elm->base.key);
 204                         }
 205                 }
 206                 ++prune->stat_scanrecords;
 207
 208                 /*
 209                  * Bad hack for now, don't blow out the kernel's buffer
 210                  * cache.  NOTE: We still hold locks on the cursor, we
 211                  * cannot call the flusher synchronously.
 212                  */
 213                 if (trans->hmp->locked_dirty_count +
 214                     trans->hmp->io_running_count > hammer_limit_dirtybufs) {
 215                         hammer_flusher_async(trans->hmp);
 216                         tsleep(trans, 0, "hmrslo", hz / 10);
 217                 }
 218                 error = hammer_signal_check(trans->hmp);
 219                 if (error == 0)
 220                         error = hammer_btree_iterate_reverse(&cursor);
 221         }
 222         hammer_sync_unlock(trans);
 223         if (error == ENOENT)
 224                 error = 0;
 225         hammer_done_cursor(&cursor);
 226         if (error == EDEADLK)
 227                 goto retry;
 228         if (error == EINTR) {
 229                 prune->head.flags |= HAMMER_IOC_HEAD_INTR;
 230                 error = 0;
 231         }
 232 failed:
 233         prune->elms = user_elms;
 234         kfree(copy_elms, M_TEMP);
 235         return(error);
 236 }
 237
 238 /*
 239  * Check pruning list.  The list must be sorted in descending order.
 240  */
 241 static int
 242 check_prune(struct hammer_ioc_prune *prune, hammer_btree_elm_t elm,
 243             int *realign_cre, int *realign_del)
 244 {
 245         struct hammer_ioc_prune_elm *scan;
 246         int i;
 247
 248         *realign_cre = -1;
 249         *realign_del = -1;
 250
 251         /*
 252          * If pruning everything remove all records with a non-zero
 253          * delete_tid.
 254          */
 255         if (prune->head.flags & HAMMER_IOC_PRUNE_ALL) {
 256                 if (elm->base.delete_tid != 0)
 257                         return(0);
 258                 return(-1);
 259         }
 260
 261         for (i = 0; i < prune->nelms; ++i) {
 262                 scan = &prune->elms[i];
 263
 264                 /*
 265                  * Locate the scan index covering the create and delete TIDs.
 266                  */
 267                 if (*realign_cre < 0 &&
 268                     elm->base.create_tid >= scan->beg_tid &&
 269                     elm->base.create_tid < scan->end_tid) {
 270                         *realign_cre = i;
 271                 }
 272                 if (*realign_del < 0 && elm->base.delete_tid &&
 273                     elm->base.delete_tid > scan->beg_tid &&
 274                     elm->base.delete_tid <= scan->end_tid) {
 275                         *realign_del = i;
 276                 }
 277
 278                 /*
 279                  * Now check for loop termination.
 280                  */
 281                 if (elm->base.create_tid >= scan->end_tid ||
 282                     elm->base.delete_tid > scan->end_tid) {
 283                         break;
 284                 }
 285
 286                 /*
 287                  * Now determine if we can delete the record.
 288                  */
 289                 if (elm->base.delete_tid &&
 290                     elm->base.create_tid >= scan->beg_tid &&
 291                     elm->base.delete_tid <= scan->end_tid &&
 292                     (elm->base.create_tid - scan->beg_tid) / scan->mod_tid ==
 293                     (elm->base.delete_tid - scan->beg_tid) / scan->mod_tid) {
 294                         return(0);
 295                 }
 296         }
 297         return(-1);
 298 }
 299
 300 /*
 301  * Align the record to cover any gaps created through the deletion of
 302  * records within the pruning space.  If we were to just delete the records
 303  * there would be gaps which in turn would cause a snapshot that is NOT on
 304  * a pruning boundary to appear corrupt to the user.  Forcing alignment
 305  * of the create_tid and delete_tid for retained records 'reconnects'
 306  * the previously contiguous space, making it contiguous again after the
 307  * deletions.
 308  *
 309  * The use of a reverse iteration allows us to safely align the records and
 310  * related elements without creating temporary overlaps.  XXX we should
 311  * add ordering dependancies for record buffers to guarantee consistency
 312  * during recovery.
 313  */
 314 static int
 315 realign_prune(struct hammer_ioc_prune *prune,
 316               hammer_cursor_t cursor, int realign_cre, int realign_del)
 317 {
 318         struct hammer_ioc_prune_elm *scan;
 319         hammer_btree_elm_t elm;
 320         hammer_tid_t delta;
 321         hammer_tid_t tid;
 322         int error;
 323
 324         hammer_cursor_downgrade(cursor);
 325
 326         elm = &cursor->node->ondisk->elms[cursor->index];
 327         ++prune->stat_realignments;
 328
 329         /*
 330          * Align the create_tid.  By doing a reverse iteration we guarantee
 331          * that all records after our current record have already been
 332          * aligned, allowing us to safely correct the right-hand-boundary
 333          * (because no record to our right is otherwise exactly matching
 334          * will have a create_tid to the left of our aligned create_tid).
 335          */
 336         error = 0;
 337         if (realign_cre >= 0) {
 338                 scan = &prune->elms[realign_cre];
 339
 340                 delta = (elm->leaf.base.create_tid - scan->beg_tid) %
 341                         scan->mod_tid;
 342                 if (delta) {
 343                         tid = elm->leaf.base.create_tid - delta + scan->mod_tid;
 344
 345                         /* can EDEADLK */
 346                         error = hammer_btree_correct_rhb(cursor, tid + 1);
 347                         if (error == 0) {
 348                                 error = hammer_btree_extract(cursor,
 349                                                      HAMMER_CURSOR_GET_LEAF);
 350                         }
 351                         if (error == 0) {
 352                                 /* can EDEADLK */
 353                                 error = hammer_cursor_upgrade(cursor);
 354                         }
 355                         if (error == 0) {
 356                                 hammer_modify_node(cursor->trans, cursor->node,
 357                                             &elm->leaf.base.create_tid,
 358                                             sizeof(elm->leaf.base.create_tid));
 359                                 elm->leaf.base.create_tid = tid;
 360                                 hammer_modify_node_done(cursor->node);
 361                         }
 362                 }
 363         }
 364
 365         /*
 366          * Align the delete_tid.  This only occurs if the record is historical
 367          * was deleted at some point.  Realigning the delete_tid does not
 368          * move the record within the B-Tree but may cause it to temporarily
 369          * overlap a record that has not yet been pruned.
 370          */
 371         if (error == 0 && realign_del >= 0) {
 372                 scan = &prune->elms[realign_del];
 373
 374                 delta = (elm->leaf.base.delete_tid - scan->beg_tid) %
 375                         scan->mod_tid;
 376                 if (delta) {
 377                         error = hammer_btree_extract(cursor,
 378                                                      HAMMER_CURSOR_GET_LEAF);
 379                         if (error == 0) {
 380                                 hammer_modify_node(cursor->trans, cursor->node,
 381                                             &elm->leaf.base.delete_tid,
 382                                             sizeof(elm->leaf.base.delete_tid));
 383                                 elm->leaf.base.delete_tid =
 384                                             elm->leaf.base.delete_tid -
 385                                             delta + scan->mod_tid;
 386                                 hammer_modify_node_done(cursor->node);
 387                         }
 388                 }
 389         }
 390         return (error);
 391 }
 392