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         int64_t bytes;
  65         uint32_t key_beg_localization;
  66
  67         if (prune->nelms < 0 || prune->nelms > HAMMER_MAX_PRUNE_ELMS)
  68                 return(EINVAL);
  69         if ((prune->key_beg.localization | prune->key_end.localization) &
  70             HAMMER_LOCALIZE_PSEUDOFS_MASK) {
  71                 return(EINVAL);
  72         }
  73         if (prune->key_beg.localization > prune->key_end.localization)
  74                 return(EINVAL);
  75         if (prune->key_beg.localization == prune->key_end.localization) {
  76                 if (prune->key_beg.obj_id > prune->key_end.obj_id)
  77                         return(EINVAL);
  78                 /* key-space limitations - no check needed */
  79         }
  80         if ((prune->head.flags & HAMMER_IOC_PRUNE_ALL) && prune->nelms)
  81                 return(EINVAL);
  82
  83         /*
  84          * Ioctl caller has only set localization type to prune.
  85          * Initialize cursor key localization with ip localization.
  86          */
  87         key_beg_localization = prune->key_beg.localization;
  88         key_beg_localization &= HAMMER_LOCALIZE_MASK;
  89         key_beg_localization |= ip->obj_localization;
  90
  91         prune->key_cur.localization = prune->key_end.localization;
  92         prune->key_cur.localization &= HAMMER_LOCALIZE_MASK;
  93         prune->key_cur.localization |= ip->obj_localization;
  94
  95         prune->key_cur.obj_id = prune->key_end.obj_id;
  96         prune->key_cur.key = HAMMER_MAX_KEY;
  97
  98         /*
  99          * Copy element array from userland
 100          */
 101         elm_array_size = sizeof(*copy_elms) * prune->nelms;
 102         user_elms = prune->elms;
 103         copy_elms = kmalloc(elm_array_size, M_TEMP, M_WAITOK);
 104         if ((error = copyin(user_elms, copy_elms, elm_array_size)) != 0)
 105                 goto failed;
 106         prune->elms = copy_elms;
 107
 108         seq = trans->hmp->flusher.done;
 109
 110         /*
 111          * Scan backwards.  Retries typically occur if a deadlock is detected.
 112          */
 113 retry:
 114         error = hammer_init_cursor(trans, &cursor, NULL, NULL);
 115         if (error) {
 116                 hammer_done_cursor(&cursor);
 117                 goto failed;
 118         }
 119         cursor.key_beg.localization = key_beg_localization;
 120         cursor.key_beg.obj_id = prune->key_beg.obj_id;
 121         cursor.key_beg.key = HAMMER_MIN_KEY;
 122         cursor.key_beg.create_tid = 1;
 123         cursor.key_beg.delete_tid = 0;
 124         cursor.key_beg.rec_type = HAMMER_MIN_RECTYPE;
 125         cursor.key_beg.obj_type = 0;
 126
 127         cursor.key_end.localization = prune->key_cur.localization;
 128         cursor.key_end.obj_id = prune->key_cur.obj_id;
 129         cursor.key_end.key = prune->key_cur.key;
 130         cursor.key_end.create_tid = HAMMER_MAX_TID - 1;
 131         cursor.key_end.delete_tid = 0;
 132         cursor.key_end.rec_type = HAMMER_MAX_RECTYPE;
 133         cursor.key_end.obj_type = 0;
 134
 135         cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE;
 136         cursor.flags |= HAMMER_CURSOR_BACKEND;
 137
 138         /*
 139          * This flag allows the B-Tree code to clean up loose ends.  At
 140          * the moment (XXX) it also means we have to hold the sync lock
 141          * through the iteration.
 142          */
 143         cursor.flags |= HAMMER_CURSOR_PRUNING;
 144
 145         hammer_sync_lock_sh(trans);
 146         error = hammer_btree_last(&cursor);
 147         hammer_sync_unlock(trans);
 148
 149         while (error == 0) {
 150                 /*
 151                  * Check for work
 152                  */
 153                 elm = &cursor.node->ondisk->elms[cursor.index].leaf;
 154                 prune->key_cur = elm->base;
 155
 156                 /*
 157                  * Filesystem went read-only during rebalancing
 158                  */
 159                 if (trans->hmp->ronly) {
 160                         error = EROFS;
 161                         break;
 162                 }
 163
 164                 /*
 165                  * Yield to more important tasks
 166                  */
 167                 if ((error = hammer_signal_check(trans->hmp)) != 0)
 168                         break;
 169
 170                 if (prune->stat_oldest_tid > elm->base.create_tid)
 171                         prune->stat_oldest_tid = elm->base.create_tid;
 172
 173                 if (hammer_debug_general & 0x0200) {
 174                         hdkprintf("check %016jx %016jx cre=%016jx del=%016jx\n",
 175                                         (intmax_t)elm->base.obj_id,
 176                                         (intmax_t)elm->base.key,
 177                                         (intmax_t)elm->base.create_tid,
 178                                         (intmax_t)elm->base.delete_tid);
 179                 }
 180
 181                 if (prune_should_delete(prune, elm)) {
 182                         if (hammer_debug_general & 0x0200) {
 183                                 hdkprintf("check %016jx %016jx: DELETE\n",
 184                                         (intmax_t)elm->base.obj_id,
 185                                         (intmax_t)elm->base.key);
 186                         }
 187
 188                         /*
 189                          * NOTE: This can return EDEADLK
 190                          *
 191                          * Acquiring the sync lock guarantees that the
 192                          * operation will not cross a synchronization
 193                          * boundary (see the flusher).
 194                          *
 195                          * We dont need to track inodes or next_tid when
 196                          * we are destroying deleted records.
 197                          */
 198                         isdir = (elm->base.rec_type == HAMMER_RECTYPE_DIRENTRY);
 199
 200                         hammer_sync_lock_sh(trans);
 201                         error = hammer_delete_at_cursor(&cursor,
 202                                                         HAMMER_DELETE_DESTROY,
 203                                                         cursor.trans->tid,
 204                                                         cursor.trans->time32,
 205                                                         0, &bytes);
 206                         hammer_sync_unlock(trans);
 207                         if (error)
 208                                 break;
 209
 210                         if (isdir)
 211                                 ++prune->stat_dirrecords;
 212                         else
 213                                 ++prune->stat_rawrecords;
 214                         prune->stat_bytes += bytes;
 215
 216                         /*
 217                          * The current record might now be the one after
 218                          * the one we deleted, set ATEDISK to force us
 219                          * to skip it (since we are iterating backwards).
 220                          */
 221                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 222                 } else {
 223                         /*
 224                          * Nothing to delete, but we may have to check other
 225                          * things.
 226                          */
 227                         prune_check_nlinks(&cursor, elm);
 228                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 229                         if (hammer_debug_general & 0x0100) {
 230                                 hdkprintf("check %016jx %016jx: SKIP\n",
 231                                         (intmax_t)elm->base.obj_id,
 232                                         (intmax_t)elm->base.key);
 233                         }
 234                 }
 235                 ++prune->stat_scanrecords;
 236
 237                 /*
 238                  * WARNING: See warnings in hammer_unlock_cursor() function.
 239                  */
 240                 while (hammer_flusher_meta_halflimit(trans->hmp) ||
 241                        hammer_flusher_undo_exhausted(trans, 2)) {
 242                         hammer_unlock_cursor(&cursor);
 243                         hammer_flusher_wait(trans->hmp, seq);
 244                         hammer_lock_cursor(&cursor);
 245                         seq = hammer_flusher_async_one(trans->hmp);
 246                 }
 247                 hammer_sync_lock_sh(trans);
 248                 error = hammer_btree_iterate_reverse(&cursor);
 249                 hammer_sync_unlock(trans);
 250         }
 251         if (error == ENOENT)
 252                 error = 0;
 253         hammer_done_cursor(&cursor);
 254         if (error == EDEADLK)
 255                 goto retry;
 256         if (error == EINTR) {
 257                 prune->head.flags |= HAMMER_IOC_HEAD_INTR;
 258                 error = 0;
 259         }
 260 failed:
 261         prune->key_cur.localization &= HAMMER_LOCALIZE_MASK;
 262         prune->elms = user_elms;
 263         kfree(copy_elms, M_TEMP);
 264         return(error);
 265 }
 266
 267 /*
 268  * Check pruning list.  The list must be sorted in descending order.
 269  *
 270  * Return non-zero if the record should be deleted.
 271  */
 272 static int
 273 prune_should_delete(struct hammer_ioc_prune *prune, hammer_btree_leaf_elm_t elm)
 274 {
 275         struct hammer_ioc_prune_elm *scan;
 276         int i;
 277
 278         /*
 279          * If pruning everything remove all records with a non-zero
 280          * delete_tid.
 281          */
 282         if (prune->head.flags & HAMMER_IOC_PRUNE_ALL) {
 283                 if (elm->base.delete_tid != 0)
 284                         return(1);
 285                 return(0);
 286         }
 287
 288         for (i = 0; i < prune->nelms; ++i) {
 289                 scan = &prune->elms[i];
 290
 291                 /*
 292                  * Check for loop termination.
 293                  */
 294                 if (elm->base.create_tid >= scan->end_tid ||
 295                     elm->base.delete_tid > scan->end_tid) {
 296                         break;
 297                 }
 298
 299                 /*
 300                  * Determine if we can delete the record.
 301                  */
 302                 if (elm->base.delete_tid &&
 303                     elm->base.create_tid >= scan->beg_tid &&
 304                     elm->base.delete_tid <= scan->end_tid &&
 305                     (elm->base.create_tid - scan->beg_tid) / scan->mod_tid ==
 306                     (elm->base.delete_tid - scan->beg_tid) / scan->mod_tid) {
 307                         return(1);
 308                 }
 309         }
 310         return(0);
 311 }
 312
 313 /*
 314  * Dangling inodes can occur if processes are holding open descriptors on
 315  * deleted files as-of when a machine crashes.  When we find one simply
 316  * acquire the inode and release it.  The inode handling code will then
 317  * do the right thing.
 318  */
 319 static
 320 void
 321 prune_check_nlinks(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm)
 322 {
 323         hammer_inode_t ip;
 324         int error;
 325
 326         if (elm->base.rec_type != HAMMER_RECTYPE_INODE)
 327                 return;
 328         if (elm->base.delete_tid != 0)
 329                 return;
 330         if (hammer_btree_extract_data(cursor))
 331                 return;
 332         if (cursor->data->inode.nlinks)
 333                 return;
 334         hammer_cursor_downgrade(cursor);
 335         ip = hammer_get_inode(cursor->trans, NULL, elm->base.obj_id,
 336                       HAMMER_MAX_TID,
 337                       elm->base.localization & HAMMER_LOCALIZE_PSEUDOFS_MASK,
 338                       0, &error);
 339         if (ip) {
 340                 if (hammer_debug_general & 0x0001) {
 341                         hdkprintf("pruning disconnected inode %016jx\n",
 342                                 (intmax_t)elm->base.obj_id);
 343                 }
 344                 hammer_rel_inode(ip, 0);
 345                 hammer_inode_waitreclaims(cursor->trans);
 346         } else {
 347                 hkprintf("unable to prune disconnected inode %016jx\n",
 348                         (intmax_t)elm->base.obj_id);
 349         }
 350 }
 351
 352 #if 0
 353
 354 /*
 355  * NOTE: THIS CODE HAS BEEN REMOVED!  Pruning no longer attempts to realign
 356  *       adjacent records because it seriously interferes with every
 357  *       mirroring algorithm I could come up with.
 358  *
 359  *       This means that historical accesses beyond the first snapshot
 360  *       softlink should be on snapshot boundaries only.  Historical
 361  *       accesses from "now" to the first snapshot softlink continue to
 362  *       be fine-grained.
 363  *
 364  * NOTE: It also looks like there's a bug in the removed code.  It is believed
 365  *       that create_tid can sometimes get set to 0xffffffffffffffff.  Just as
 366  *       well we no longer try to do this fancy shit.  Probably the attempt to
 367  *       correct the rhb is blowing up the cursor's indexing or addressing mapping.
 368  *
 369  * Align the record to cover any gaps created through the deletion of
 370  * records within the pruning space.  If we were to just delete the records
 371  * there would be gaps which in turn would cause a snapshot that is NOT on
 372  * a pruning boundary to appear corrupt to the user.  Forcing alignment
 373  * of the create_tid and delete_tid for retained records 'reconnects'
 374  * the previously contiguous space, making it contiguous again after the
 375  * deletions.
 376  *
 377  * The use of a reverse iteration allows us to safely align the records and
 378  * related elements without creating temporary overlaps.  XXX we should
 379  * add ordering dependancies for record buffers to guarantee consistency
 380  * during recovery.
 381  */
 382 static int
 383 realign_prune(struct hammer_ioc_prune *prune,
 384               hammer_cursor_t cursor, int realign_cre, int realign_del)
 385 {
 386         struct hammer_ioc_prune_elm *scan;
 387         hammer_btree_elm_t elm;
 388         hammer_tid_t delta;
 389         hammer_tid_t tid;
 390         int error;
 391
 392         hammer_cursor_downgrade(cursor);
 393
 394         elm = &cursor->node->ondisk->elms[cursor->index];
 395         ++prune->stat_realignments;
 396
 397         /*
 398          * Align the create_tid.  By doing a reverse iteration we guarantee
 399          * that all records after our current record have already been
 400          * aligned, allowing us to safely correct the right-hand-boundary
 401          * (because no record to our right is otherwise exactly matching
 402          * will have a create_tid to the left of our aligned create_tid).
 403          */
 404         error = 0;
 405         if (realign_cre >= 0) {
 406                 scan = &prune->elms[realign_cre];
 407
 408                 delta = (elm->leaf.base.create_tid - scan->beg_tid) %
 409                         scan->mod_tid;
 410                 if (delta) {
 411                         tid = elm->leaf.base.create_tid - delta + scan->mod_tid;
 412
 413                         /* can EDEADLK */
 414                         error = hammer_btree_correct_rhb(cursor, tid + 1);
 415                         if (error == 0) {
 416                                 error = hammer_btree_extract_leaf(cursor);
 417                         }
 418                         if (error == 0) {
 419                                 /* can EDEADLK */
 420                                 error = hammer_cursor_upgrade(cursor);
 421                         }
 422                         if (error == 0) {
 423                                 hammer_modify_node(cursor->trans, cursor->node,
 424                                             &elm->leaf.base.create_tid,
 425                                             sizeof(elm->leaf.base.create_tid));
 426                                 elm->leaf.base.create_tid = tid;
 427                                 hammer_modify_node_done(cursor->node);
 428                         }
 429                 }
 430         }
 431
 432         /*
 433          * Align the delete_tid.  This only occurs if the record is historical
 434          * was deleted at some point.  Realigning the delete_tid does not
 435          * move the record within the B-Tree but may cause it to temporarily
 436          * overlap a record that has not yet been pruned.
 437          */
 438         if (error == 0 && realign_del >= 0) {
 439                 scan = &prune->elms[realign_del];
 440
 441                 delta = (elm->leaf.base.delete_tid - scan->beg_tid) %
 442                         scan->mod_tid;
 443                 if (delta) {
 444                         error = hammer_btree_extract_leaf(cursor);
 445                         if (error == 0) {
 446                                 hammer_modify_node(cursor->trans, cursor->node,
 447                                             &elm->leaf.base.delete_tid,
 448                                             sizeof(elm->leaf.base.delete_tid));
 449                                 elm->leaf.base.delete_tid =
 450                                             elm->leaf.base.delete_tid -
 451                                             delta + scan->mod_tid;
 452                                 hammer_modify_node_done(cursor->node);
 453                         }
 454                 }
 455         }
 456         return (error);
 457 }
 458
 459 #endif