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 1.19 2008/09/23 21:03:52 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 prune_should_delete(struct hammer_ioc_prune *prune,
  48                                hammer_btree_leaf_elm_t elm);
  49 static void prune_check_nlinks(hammer_cursor_t cursor,
  50                                hammer_btree_leaf_elm_t elm);
  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_leaf_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 elm_array_size;
  63         int seq;
  64
  65         if (prune->nelms < 0 || prune->nelms > HAMMER_MAX_PRUNE_ELMS)
  66                 return(EINVAL);
  67         if ((prune->key_beg.localization | prune->key_end.localization) &
  68             HAMMER_LOCALIZE_PSEUDOFS_MASK) {
  69                 return(EINVAL);
  70         }
  71         if (prune->key_beg.localization > prune->key_end.localization)
  72                 return(EINVAL);
  73         if (prune->key_beg.localization == prune->key_end.localization) {
  74                 if (prune->key_beg.obj_id > prune->key_end.obj_id)
  75                         return(EINVAL);
  76                 /* key-space limitations - no check needed */
  77         }
  78         if ((prune->head.flags & HAMMER_IOC_PRUNE_ALL) && prune->nelms)
  79                 return(EINVAL);
  80
  81         prune->key_cur.localization = (prune->key_end.localization &
  82                                         HAMMER_LOCALIZE_MASK) +
  83                                       ip->obj_localization;
  84         prune->key_cur.obj_id = prune->key_end.obj_id;
  85         prune->key_cur.key = HAMMER_MAX_KEY;
  86
  87         /*
  88          * Copy element array from userland
  89          */
  90         elm_array_size = sizeof(*copy_elms) * prune->nelms;
  91         user_elms = prune->elms;
  92         copy_elms = kmalloc(elm_array_size, M_TEMP, M_WAITOK);
  93         if ((error = copyin(user_elms, copy_elms, elm_array_size)) != 0)
  94                 goto failed;
  95         prune->elms = copy_elms;
  96
  97         seq = trans->hmp->flusher.act;
  98
  99         /*
 100          * Scan backwards.  Retries typically occur if a deadlock is detected.
 101          */
 102 retry:
 103         error = hammer_init_cursor(trans, &cursor, NULL, NULL);
 104         if (error) {
 105                 hammer_done_cursor(&cursor);
 106                 goto failed;
 107         }
 108         cursor.key_beg.localization = (prune->key_beg.localization &
 109                                         HAMMER_LOCALIZE_MASK) +
 110                                       ip->obj_localization;
 111         cursor.key_beg.obj_id = prune->key_beg.obj_id;
 112         cursor.key_beg.key = HAMMER_MIN_KEY;
 113         cursor.key_beg.create_tid = 1;
 114         cursor.key_beg.delete_tid = 0;
 115         cursor.key_beg.rec_type = HAMMER_MIN_RECTYPE;
 116         cursor.key_beg.obj_type = 0;
 117
 118         cursor.key_end.localization = prune->key_cur.localization;
 119         cursor.key_end.obj_id = prune->key_cur.obj_id;
 120         cursor.key_end.key = prune->key_cur.key;
 121         cursor.key_end.create_tid = HAMMER_MAX_TID - 1;
 122         cursor.key_end.delete_tid = 0;
 123         cursor.key_end.rec_type = HAMMER_MAX_RECTYPE;
 124         cursor.key_end.obj_type = 0;
 125
 126         cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE;
 127         cursor.flags |= HAMMER_CURSOR_BACKEND;
 128
 129         /*
 130          * This flag allows the B-Tree code to clean up loose ends.  At
 131          * the moment (XXX) it also means we have to hold the sync lock
 132          * through the iteration.
 133          */
 134         cursor.flags |= HAMMER_CURSOR_PRUNING;
 135
 136         hammer_sync_lock_sh(trans);
 137         error = hammer_btree_last(&cursor);
 138         hammer_sync_unlock(trans);
 139
 140         while (error == 0) {
 141                 /*
 142                  * Check for work
 143                  */
 144                 elm = &cursor.node->ondisk->elms[cursor.index].leaf;
 145                 prune->key_cur = elm->base;
 146
 147                 /*
 148                  * Yield to more important tasks
 149                  */
 150                 if ((error = hammer_signal_check(trans->hmp)) != 0)
 151                         break;
 152
 153                 if (prune->stat_oldest_tid > elm->base.create_tid)
 154                         prune->stat_oldest_tid = elm->base.create_tid;
 155
 156                 if (hammer_debug_general & 0x0200) {
 157                         kprintf("check %016llx %016llx cre=%016llx del=%016llx\n",
 158                                         (long long)elm->base.obj_id,
 159                                         (long long)elm->base.key,
 160                                         (long long)elm->base.create_tid,
 161                                         (long long)elm->base.delete_tid);
 162                 }
 163
 164                 if (prune_should_delete(prune, elm)) {
 165                         if (hammer_debug_general & 0x0200) {
 166                                 kprintf("check %016llx %016llx: DELETE\n",
 167                                         (long long)elm->base.obj_id,
 168                                         (long long)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                          * We dont need to track inodes or next_tid when
 179                          * we are destroying deleted records.
 180                          */
 181                         isdir = (elm->base.rec_type == HAMMER_RECTYPE_DIRENTRY);
 182
 183                         hammer_sync_lock_sh(trans);
 184                         error = hammer_delete_at_cursor(&cursor,
 185                                                         HAMMER_DELETE_DESTROY,
 186                                                         cursor.trans->tid,
 187                                                         cursor.trans->time32,
 188                                                         0, &prune->stat_bytes);
 189                         hammer_sync_unlock(trans);
 190                         if (error)
 191                                 break;
 192
 193                         if (isdir)
 194                                 ++prune->stat_dirrecords;
 195                         else
 196                                 ++prune->stat_rawrecords;
 197
 198                         /*
 199                          * The current record might now be the one after
 200                          * the one we deleted, set ATEDISK to force us
 201                          * to skip it (since we are iterating backwards).
 202                          */
 203                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 204                 } else {
 205                         /*
 206                          * Nothing to delete, but we may have to check other
 207                          * things.
 208                          */
 209                         prune_check_nlinks(&cursor, elm);
 210                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 211                         if (hammer_debug_general & 0x0100) {
 212                                 kprintf("check %016llx %016llx: SKIP\n",
 213                                         (long long)elm->base.obj_id,
 214                                         (long long)elm->base.key);
 215                         }
 216                 }
 217                 ++prune->stat_scanrecords;
 218
 219                 /*
 220                  * WARNING: See warnings in hammer_unlock_cursor() function.
 221                  */
 222                 while (hammer_flusher_meta_halflimit(trans->hmp) ||
 223                        hammer_flusher_undo_exhausted(trans, 2)) {
 224                         hammer_unlock_cursor(&cursor);
 225                         hammer_flusher_wait(trans->hmp, seq);
 226                         hammer_lock_cursor(&cursor);
 227                         seq = hammer_flusher_async_one(trans->hmp);
 228                 }
 229                 hammer_sync_lock_sh(trans);
 230                 error = hammer_btree_iterate_reverse(&cursor);
 231                 hammer_sync_unlock(trans);
 232         }
 233         if (error == ENOENT)
 234                 error = 0;
 235         hammer_done_cursor(&cursor);
 236         if (error == EDEADLK)
 237                 goto retry;
 238         if (error == EINTR) {
 239                 prune->head.flags |= HAMMER_IOC_HEAD_INTR;
 240                 error = 0;
 241         }
 242 failed:
 243         prune->key_cur.localization &= HAMMER_LOCALIZE_MASK;
 244         prune->elms = user_elms;
 245         kfree(copy_elms, M_TEMP);
 246         return(error);
 247 }
 248
 249 /*
 250  * Check pruning list.  The list must be sorted in descending order.
 251  *
 252  * Return non-zero if the record should be deleted.
 253  */
 254 static int
 255 prune_should_delete(struct hammer_ioc_prune *prune, hammer_btree_leaf_elm_t elm)
 256 {
 257         struct hammer_ioc_prune_elm *scan;
 258         int i;
 259
 260         /*
 261          * If pruning everything remove all records with a non-zero
 262          * delete_tid.
 263          */
 264         if (prune->head.flags & HAMMER_IOC_PRUNE_ALL) {
 265                 if (elm->base.delete_tid != 0)
 266                         return(1);
 267                 return(0);
 268         }
 269
 270         for (i = 0; i < prune->nelms; ++i) {
 271                 scan = &prune->elms[i];
 272
 273                 /*
 274                  * Check for loop termination.
 275                  */
 276                 if (elm->base.create_tid >= scan->end_tid ||
 277                     elm->base.delete_tid > scan->end_tid) {
 278                         break;
 279                 }
 280
 281                 /*
 282                  * Determine if we can delete the record.
 283                  */
 284                 if (elm->base.delete_tid &&
 285                     elm->base.create_tid >= scan->beg_tid &&
 286                     elm->base.delete_tid <= scan->end_tid &&
 287                     (elm->base.create_tid - scan->beg_tid) / scan->mod_tid ==
 288                     (elm->base.delete_tid - scan->beg_tid) / scan->mod_tid) {
 289                         return(1);
 290                 }
 291         }
 292         return(0);
 293 }
 294
 295 /*
 296  * Dangling inodes can occur if processes are holding open descriptors on
 297  * deleted files as-of when a machine crashes.  When we find one simply
 298  * acquire the inode and release it.  The inode handling code will then
 299  * do the right thing.
 300  */
 301 static
 302 void
 303 prune_check_nlinks(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm)
 304 {
 305         hammer_inode_t ip;
 306         int error;
 307
 308         if (elm->base.rec_type != HAMMER_RECTYPE_INODE)
 309                 return;
 310         if (elm->base.delete_tid != 0)
 311                 return;
 312         if (hammer_btree_extract(cursor, HAMMER_CURSOR_GET_DATA))
 313                 return;
 314         if (cursor->data->inode.nlinks)
 315                 return;
 316         hammer_cursor_downgrade(cursor);
 317         ip = hammer_get_inode(cursor->trans, NULL, elm->base.obj_id,
 318                       HAMMER_MAX_TID,
 319                       elm->base.localization & HAMMER_LOCALIZE_PSEUDOFS_MASK,
 320                       0, &error);
 321         if (ip) {
 322                 if (hammer_debug_general & 0x0001) {
 323                         kprintf("pruning disconnected inode %016llx\n",
 324                                 (long long)elm->base.obj_id);
 325                 }
 326                 hammer_rel_inode(ip, 0);
 327                 hammer_inode_waitreclaims(cursor->trans);
 328         } else {
 329                 kprintf("unable to prune disconnected inode %016llx\n",
 330                         (long long)elm->base.obj_id);
 331         }
 332 }
 333
 334 #if 0
 335
 336 /*
 337  * NOTE: THIS CODE HAS BEEN REMOVED!  Pruning no longer attempts to realign
 338  *       adjacent records because it seriously interferes with every
 339  *       mirroring algorithm I could come up with.
 340  *
 341  *       This means that historical accesses beyond the first snapshot
 342  *       softlink should be on snapshot boundaries only.  Historical
 343  *       accesses from "now" to the first snapshot softlink continue to
 344  *       be fine-grained.
 345  *
 346  * NOTE: It also looks like there's a bug in the removed code.  It is believed
 347  *       that create_tid can sometimes get set to 0xffffffffffffffff.  Just as
 348  *       well we no longer try to do this fancy shit.  Probably the attempt to
 349  *       correct the rhb is blowing up the cursor's indexing or addressing mapping.
 350  *
 351  * Align the record to cover any gaps created through the deletion of
 352  * records within the pruning space.  If we were to just delete the records
 353  * there would be gaps which in turn would cause a snapshot that is NOT on
 354  * a pruning boundary to appear corrupt to the user.  Forcing alignment
 355  * of the create_tid and delete_tid for retained records 'reconnects'
 356  * the previously contiguous space, making it contiguous again after the
 357  * deletions.
 358  *
 359  * The use of a reverse iteration allows us to safely align the records and
 360  * related elements without creating temporary overlaps.  XXX we should
 361  * add ordering dependancies for record buffers to guarantee consistency
 362  * during recovery.
 363  */
 364 static int
 365 realign_prune(struct hammer_ioc_prune *prune,
 366               hammer_cursor_t cursor, int realign_cre, int realign_del)
 367 {
 368         struct hammer_ioc_prune_elm *scan;
 369         hammer_btree_elm_t elm;
 370         hammer_tid_t delta;
 371         hammer_tid_t tid;
 372         int error;
 373
 374         hammer_cursor_downgrade(cursor);
 375
 376         elm = &cursor->node->ondisk->elms[cursor->index];
 377         ++prune->stat_realignments;
 378
 379         /*
 380          * Align the create_tid.  By doing a reverse iteration we guarantee
 381          * that all records after our current record have already been
 382          * aligned, allowing us to safely correct the right-hand-boundary
 383          * (because no record to our right is otherwise exactly matching
 384          * will have a create_tid to the left of our aligned create_tid).
 385          */
 386         error = 0;
 387         if (realign_cre >= 0) {
 388                 scan = &prune->elms[realign_cre];
 389
 390                 delta = (elm->leaf.base.create_tid - scan->beg_tid) %
 391                         scan->mod_tid;
 392                 if (delta) {
 393                         tid = elm->leaf.base.create_tid - delta + scan->mod_tid;
 394
 395                         /* can EDEADLK */
 396                         error = hammer_btree_correct_rhb(cursor, tid + 1);
 397                         if (error == 0) {
 398                                 error = hammer_btree_extract(cursor,
 399                                                      HAMMER_CURSOR_GET_LEAF);
 400                         }
 401                         if (error == 0) {
 402                                 /* can EDEADLK */
 403                                 error = hammer_cursor_upgrade(cursor);
 404                         }
 405                         if (error == 0) {
 406                                 hammer_modify_node(cursor->trans, cursor->node,
 407                                             &elm->leaf.base.create_tid,
 408                                             sizeof(elm->leaf.base.create_tid));
 409                                 elm->leaf.base.create_tid = tid;
 410                                 hammer_modify_node_done(cursor->node);
 411                         }
 412                 }
 413         }
 414
 415         /*
 416          * Align the delete_tid.  This only occurs if the record is historical
 417          * was deleted at some point.  Realigning the delete_tid does not
 418          * move the record within the B-Tree but may cause it to temporarily
 419          * overlap a record that has not yet been pruned.
 420          */
 421         if (error == 0 && realign_del >= 0) {
 422                 scan = &prune->elms[realign_del];
 423
 424                 delta = (elm->leaf.base.delete_tid - scan->beg_tid) %
 425                         scan->mod_tid;
 426                 if (delta) {
 427                         error = hammer_btree_extract(cursor,
 428                                                      HAMMER_CURSOR_GET_LEAF);
 429                         if (error == 0) {
 430                                 hammer_modify_node(cursor->trans, cursor->node,
 431                                             &elm->leaf.base.delete_tid,
 432                                             sizeof(elm->leaf.base.delete_tid));
 433                                 elm->leaf.base.delete_tid =
 434                                             elm->leaf.base.delete_tid -
 435                                             delta + scan->mod_tid;
 436                                 hammer_modify_node_done(cursor->node);
 437                         }
 438                 }
 439         }
 440         return (error);
 441 }
 442
 443 #endif