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 1.13 2008/07/11 01:22:29 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
  64         if (prune->nelms < 0 || prune->nelms > HAMMER_MAX_PRUNE_ELMS)
  65                 return(EINVAL);
  66         if ((prune->key_beg.localization | prune->key_end.localization) &
  67             HAMMER_LOCALIZE_PSEUDOFS_MASK) {
  68                 return(EINVAL);
  69         }
  70         if (prune->key_beg.localization > prune->key_end.localization)
  71                 return(EINVAL);
  72         if (prune->key_beg.localization == prune->key_end.localization) {
  73                 if (prune->key_beg.obj_id > prune->key_end.obj_id)
  74                         return(EINVAL);
  75                 /* key-space limitations - no check needed */
  76         }
  77         if ((prune->head.flags & HAMMER_IOC_PRUNE_ALL) && prune->nelms)
  78                 return(EINVAL);
  79
  80         prune->key_cur.localization = prune->key_end.localization +
  81                                       ip->obj_localization;
  82         prune->key_cur.obj_id = prune->key_end.obj_id;
  83         prune->key_cur.key = HAMMER_MAX_KEY;
  84
  85         /*
  86          * Copy element array from userland
  87          */
  88         elm_array_size = sizeof(*copy_elms) * prune->nelms;
  89         user_elms = prune->elms;
  90         copy_elms = kmalloc(elm_array_size, M_TEMP, M_WAITOK);
  91         if ((error = copyin(user_elms, copy_elms, elm_array_size)) != 0)
  92                 goto failed;
  93         prune->elms = copy_elms;
  94
  95         /*
  96          * Scan backwards.  Retries typically occur if a deadlock is detected.
  97          */
  98 retry:
  99         error = hammer_init_cursor(trans, &cursor, NULL, NULL);
 100         if (error) {
 101                 hammer_done_cursor(&cursor);
 102                 goto failed;
 103         }
 104         cursor.key_beg.localization = prune->key_beg.localization +
 105                                       ip->obj_localization;
 106         cursor.key_beg.obj_id = prune->key_beg.obj_id;
 107         cursor.key_beg.key = HAMMER_MIN_KEY;
 108         cursor.key_beg.create_tid = 1;
 109         cursor.key_beg.delete_tid = 0;
 110         cursor.key_beg.rec_type = HAMMER_MIN_RECTYPE;
 111         cursor.key_beg.obj_type = 0;
 112
 113         cursor.key_end.localization = prune->key_cur.localization;
 114         cursor.key_end.obj_id = prune->key_cur.obj_id;
 115         cursor.key_end.key = prune->key_cur.key;
 116         cursor.key_end.create_tid = HAMMER_MAX_TID - 1;
 117         cursor.key_end.delete_tid = 0;
 118         cursor.key_end.rec_type = HAMMER_MAX_RECTYPE;
 119         cursor.key_end.obj_type = 0;
 120
 121         cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE;
 122         cursor.flags |= HAMMER_CURSOR_BACKEND;
 123
 124         /*
 125          * This flag allows the B-Tree code to clean up loose ends.
 126          */
 127         cursor.flags |= HAMMER_CURSOR_PRUNING;
 128
 129         error = hammer_btree_last(&cursor);
 130
 131         while (error == 0) {
 132                 /*
 133                  * Check for work
 134                  */
 135                 elm = &cursor.node->ondisk->elms[cursor.index].leaf;
 136                 prune->key_cur = elm->base;
 137
 138                 /*
 139                  * Yield to more important tasks
 140                  */
 141                 if ((error = hammer_signal_check(trans->hmp)) != 0)
 142                         break;
 143                 if (hammer_flusher_meta_limit(trans->hmp) ||
 144                     hammer_flusher_undo_exhausted(trans, 2)) {
 145                         error = EWOULDBLOCK;
 146                         break;
 147                 }
 148
 149                 if (prune->stat_oldest_tid > elm->base.create_tid)
 150                         prune->stat_oldest_tid = elm->base.create_tid;
 151
 152                 if (hammer_debug_general & 0x0200) {
 153                         kprintf("check %016llx %016llx cre=%016llx del=%016llx\n",
 154                                         elm->base.obj_id,
 155                                         elm->base.key,
 156                                         elm->base.create_tid,
 157                                         elm->base.delete_tid);
 158                 }
 159
 160                 if (prune_should_delete(prune, elm)) {
 161                         if (hammer_debug_general & 0x0200) {
 162                                 kprintf("check %016llx %016llx: DELETE\n",
 163                                         elm->base.obj_id, elm->base.key);
 164                         }
 165
 166                         /*
 167                          * NOTE: This can return EDEADLK
 168                          *
 169                          * Acquiring the sync lock guarantees that the
 170                          * operation will not cross a synchronization
 171                          * boundary (see the flusher).
 172                          */
 173                         isdir = (elm->base.rec_type == HAMMER_RECTYPE_DIRENTRY);
 174
 175                         hammer_sync_lock_sh(trans);
 176                         error = hammer_delete_at_cursor(&cursor,
 177                                                         HAMMER_DELETE_DESTROY,
 178                                                         &prune->stat_bytes);
 179                         hammer_sync_unlock(trans);
 180                         if (error)
 181                                 break;
 182
 183                         if (isdir)
 184                                 ++prune->stat_dirrecords;
 185                         else
 186                                 ++prune->stat_rawrecords;
 187
 188                         /*
 189                          * The current record might now be the one after
 190                          * the one we deleted, set ATEDISK to force us
 191                          * to skip it (since we are iterating backwards).
 192                          */
 193                         cursor.flags |= HAMMER_CURSOR_ATEDISK;
 194                 } else {
 195                         /*
 196                          * Nothing to delete, but we may have to check other
 197                          * things.
 198                          */
 199                         prune_check_nlinks(&cursor, elm);
 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                 error = hammer_btree_iterate_reverse(&cursor);
 208         }
 209         if (error == ENOENT)
 210                 error = 0;
 211         hammer_done_cursor(&cursor);
 212         if (error == EWOULDBLOCK) {
 213                 hammer_flusher_sync(trans->hmp);
 214                 goto retry;
 215         }
 216         if (error == EDEADLK)
 217                 goto retry;
 218         if (error == EINTR) {
 219                 prune->head.flags |= HAMMER_IOC_HEAD_INTR;
 220                 error = 0;
 221         }
 222 failed:
 223         prune->key_cur.localization &= HAMMER_LOCALIZE_MASK;
 224         prune->elms = user_elms;
 225         kfree(copy_elms, M_TEMP);
 226         return(error);
 227 }
 228
 229 /*
 230  * Check pruning list.  The list must be sorted in descending order.
 231  *
 232  * Return non-zero if the record should be deleted.
 233  */
 234 static int
 235 prune_should_delete(struct hammer_ioc_prune *prune, hammer_btree_leaf_elm_t elm)
 236 {
 237         struct hammer_ioc_prune_elm *scan;
 238         int i;
 239
 240         /*
 241          * If pruning everything remove all records with a non-zero
 242          * delete_tid.
 243          */
 244         if (prune->head.flags & HAMMER_IOC_PRUNE_ALL) {
 245                 if (elm->base.delete_tid != 0)
 246                         return(1);
 247                 return(0);
 248         }
 249
 250         for (i = 0; i < prune->nelms; ++i) {
 251                 scan = &prune->elms[i];
 252
 253                 /*
 254                  * Check for loop termination.
 255                  */
 256                 if (elm->base.create_tid >= scan->end_tid ||
 257                     elm->base.delete_tid > scan->end_tid) {
 258                         break;
 259                 }
 260
 261                 /*
 262                  * Determine if we can delete the record.
 263                  */
 264                 if (elm->base.delete_tid &&
 265                     elm->base.create_tid >= scan->beg_tid &&
 266                     elm->base.delete_tid <= scan->end_tid &&
 267                     (elm->base.create_tid - scan->beg_tid) / scan->mod_tid ==
 268                     (elm->base.delete_tid - scan->beg_tid) / scan->mod_tid) {
 269                         return(1);
 270                 }
 271         }
 272         return(0);
 273 }
 274
 275 /*
 276  * Dangling inodes can occur if processes are holding open descriptors on
 277  * deleted files as-of when a machine crashes.  When we find one simply
 278  * acquire the inode and release it.  The inode handling code will then
 279  * do the right thing.
 280  */
 281 static
 282 void
 283 prune_check_nlinks(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm)
 284 {
 285         hammer_inode_t ip;
 286         int error;
 287
 288         if (elm->base.rec_type != HAMMER_RECTYPE_INODE)
 289                 return;
 290         if (elm->base.delete_tid != 0)
 291                 return;
 292         if (hammer_btree_extract(cursor, HAMMER_CURSOR_GET_DATA))
 293                 return;
 294         if (cursor->data->inode.nlinks)
 295                 return;
 296         hammer_cursor_downgrade(cursor);
 297         ip = hammer_get_inode(cursor->trans, NULL, elm->base.obj_id,
 298                       HAMMER_MAX_TID,
 299                       elm->base.localization & HAMMER_LOCALIZE_PSEUDOFS_MASK,
 300                       0, &error);
 301         if (ip) {
 302                 kprintf("pruning disconnected inode %016llx\n",
 303                         elm->base.obj_id);
 304                 hammer_rel_inode(ip, 0);
 305         } else {
 306                 kprintf("unable to prune disconnected inode %016llx\n",
 307                         elm->base.obj_id);
 308         }
 309 }
 310
 311 #if 0
 312
 313 /*
 314  * NOTE: THIS CODE HAS BEEN REMOVED!  Pruning no longer attempts to realign
 315  *       adjacent records because it seriously interferes with every
 316  *       mirroring algorithm I could come up with.
 317  *
 318  *       This means that historical accesses beyond the first snapshot
 319  *       softlink should be on snapshot boundaries only.  Historical
 320  *       accesses from "now" to the first snapshot softlink continue to
 321  *       be fine-grained.
 322  *
 323  * NOTE: It also looks like there's a bug in the removed code.  It is believed
 324  *       that create_tid can sometimes get set to 0xffffffffffffffff.  Just as
 325  *       well we no longer try to do this fancy shit.  Probably the attempt to
 326  *       correct the rhb is blowing up the cursor's indexing or addressing mapping.
 327  *
 328  * Align the record to cover any gaps created through the deletion of
 329  * records within the pruning space.  If we were to just delete the records
 330  * there would be gaps which in turn would cause a snapshot that is NOT on
 331  * a pruning boundary to appear corrupt to the user.  Forcing alignment
 332  * of the create_tid and delete_tid for retained records 'reconnects'
 333  * the previously contiguous space, making it contiguous again after the
 334  * deletions.
 335  *
 336  * The use of a reverse iteration allows us to safely align the records and
 337  * related elements without creating temporary overlaps.  XXX we should
 338  * add ordering dependancies for record buffers to guarantee consistency
 339  * during recovery.
 340  */
 341 static int
 342 realign_prune(struct hammer_ioc_prune *prune,
 343               hammer_cursor_t cursor, int realign_cre, int realign_del)
 344 {
 345         struct hammer_ioc_prune_elm *scan;
 346         hammer_btree_elm_t elm;
 347         hammer_tid_t delta;
 348         hammer_tid_t tid;
 349         int error;
 350
 351         hammer_cursor_downgrade(cursor);
 352
 353         elm = &cursor->node->ondisk->elms[cursor->index];
 354         ++prune->stat_realignments;
 355
 356         /*
 357          * Align the create_tid.  By doing a reverse iteration we guarantee
 358          * that all records after our current record have already been
 359          * aligned, allowing us to safely correct the right-hand-boundary
 360          * (because no record to our right is otherwise exactly matching
 361          * will have a create_tid to the left of our aligned create_tid).
 362          */
 363         error = 0;
 364         if (realign_cre >= 0) {
 365                 scan = &prune->elms[realign_cre];
 366
 367                 delta = (elm->leaf.base.create_tid - scan->beg_tid) %
 368                         scan->mod_tid;
 369                 if (delta) {
 370                         tid = elm->leaf.base.create_tid - delta + scan->mod_tid;
 371
 372                         /* can EDEADLK */
 373                         error = hammer_btree_correct_rhb(cursor, tid + 1);
 374                         if (error == 0) {
 375                                 error = hammer_btree_extract(cursor,
 376                                                      HAMMER_CURSOR_GET_LEAF);
 377                         }
 378                         if (error == 0) {
 379                                 /* can EDEADLK */
 380                                 error = hammer_cursor_upgrade(cursor);
 381                         }
 382                         if (error == 0) {
 383                                 hammer_modify_node(cursor->trans, cursor->node,
 384                                             &elm->leaf.base.create_tid,
 385                                             sizeof(elm->leaf.base.create_tid));
 386                                 elm->leaf.base.create_tid = tid;
 387                                 hammer_modify_node_done(cursor->node);
 388                         }
 389                 }
 390         }
 391
 392         /*
 393          * Align the delete_tid.  This only occurs if the record is historical
 394          * was deleted at some point.  Realigning the delete_tid does not
 395          * move the record within the B-Tree but may cause it to temporarily
 396          * overlap a record that has not yet been pruned.
 397          */
 398         if (error == 0 && realign_del >= 0) {
 399                 scan = &prune->elms[realign_del];
 400
 401                 delta = (elm->leaf.base.delete_tid - scan->beg_tid) %
 402                         scan->mod_tid;
 403                 if (delta) {
 404                         error = hammer_btree_extract(cursor,
 405                                                      HAMMER_CURSOR_GET_LEAF);
 406                         if (error == 0) {
 407                                 hammer_modify_node(cursor->trans, cursor->node,
 408                                             &elm->leaf.base.delete_tid,
 409                                             sizeof(elm->leaf.base.delete_tid));
 410                                 elm->leaf.base.delete_tid =
 411                                             elm->leaf.base.delete_tid -
 412                                             delta + scan->mod_tid;
 413                                 hammer_modify_node_done(cursor->node);
 414                         }
 415                 }
 416         }
 417         return (error);
 418 }
 419
 420 #endif