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 u_int32_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 * Yield to more important tasks 158 */ 159 if ((error = hammer_signal_check(trans->hmp)) != 0) 160 break; 161 162 if (prune->stat_oldest_tid > elm->base.create_tid) 163 prune->stat_oldest_tid = elm->base.create_tid; 164 165 if (hammer_debug_general & 0x0200) { 166 hdkprintf("check %016llx %016llx cre=%016llx del=%016llx\n", 167 (long long)elm->base.obj_id, 168 (long long)elm->base.key, 169 (long long)elm->base.create_tid, 170 (long long)elm->base.delete_tid); 171 } 172 173 if (prune_should_delete(prune, elm)) { 174 if (hammer_debug_general & 0x0200) { 175 hdkprintf("check %016llx %016llx: DELETE\n", 176 (long long)elm->base.obj_id, 177 (long long)elm->base.key); 178 } 179 180 /* 181 * NOTE: This can return EDEADLK 182 * 183 * Acquiring the sync lock guarantees that the 184 * operation will not cross a synchronization 185 * boundary (see the flusher). 186 * 187 * We dont need to track inodes or next_tid when 188 * we are destroying deleted records. 189 */ 190 isdir = (elm->base.rec_type == HAMMER_RECTYPE_DIRENTRY); 191 192 hammer_sync_lock_sh(trans); 193 error = hammer_delete_at_cursor(&cursor, 194 HAMMER_DELETE_DESTROY, 195 cursor.trans->tid, 196 cursor.trans->time32, 197 0, &bytes); 198 hammer_sync_unlock(trans); 199 if (error) 200 break; 201 202 if (isdir) 203 ++prune->stat_dirrecords; 204 else 205 ++prune->stat_rawrecords; 206 prune->stat_bytes += bytes; 207 208 /* 209 * The current record might now be the one after 210 * the one we deleted, set ATEDISK to force us 211 * to skip it (since we are iterating backwards). 212 */ 213 cursor.flags |= HAMMER_CURSOR_ATEDISK; 214 } else { 215 /* 216 * Nothing to delete, but we may have to check other 217 * things. 218 */ 219 prune_check_nlinks(&cursor, elm); 220 cursor.flags |= HAMMER_CURSOR_ATEDISK; 221 if (hammer_debug_general & 0x0100) { 222 hdkprintf("check %016llx %016llx: SKIP\n", 223 (long long)elm->base.obj_id, 224 (long long)elm->base.key); 225 } 226 } 227 ++prune->stat_scanrecords; 228 229 /* 230 * WARNING: See warnings in hammer_unlock_cursor() function. 231 */ 232 while (hammer_flusher_meta_halflimit(trans->hmp) || 233 hammer_flusher_undo_exhausted(trans, 2)) { 234 hammer_unlock_cursor(&cursor); 235 hammer_flusher_wait(trans->hmp, seq); 236 hammer_lock_cursor(&cursor); 237 seq = hammer_flusher_async_one(trans->hmp); 238 } 239 hammer_sync_lock_sh(trans); 240 error = hammer_btree_iterate_reverse(&cursor); 241 hammer_sync_unlock(trans); 242 } 243 if (error == ENOENT) 244 error = 0; 245 hammer_done_cursor(&cursor); 246 if (error == EDEADLK) 247 goto retry; 248 if (error == EINTR) { 249 prune->head.flags |= HAMMER_IOC_HEAD_INTR; 250 error = 0; 251 } 252 failed: 253 prune->key_cur.localization &= HAMMER_LOCALIZE_MASK; 254 prune->elms = user_elms; 255 kfree(copy_elms, M_TEMP); 256 return(error); 257 } 258 259 /* 260 * Check pruning list. The list must be sorted in descending order. 261 * 262 * Return non-zero if the record should be deleted. 263 */ 264 static int 265 prune_should_delete(struct hammer_ioc_prune *prune, hammer_btree_leaf_elm_t elm) 266 { 267 struct hammer_ioc_prune_elm *scan; 268 int i; 269 270 /* 271 * If pruning everything remove all records with a non-zero 272 * delete_tid. 273 */ 274 if (prune->head.flags & HAMMER_IOC_PRUNE_ALL) { 275 if (elm->base.delete_tid != 0) 276 return(1); 277 return(0); 278 } 279 280 for (i = 0; i < prune->nelms; ++i) { 281 scan = &prune->elms[i]; 282 283 /* 284 * Check for loop termination. 285 */ 286 if (elm->base.create_tid >= scan->end_tid || 287 elm->base.delete_tid > scan->end_tid) { 288 break; 289 } 290 291 /* 292 * Determine if we can delete the record. 293 */ 294 if (elm->base.delete_tid && 295 elm->base.create_tid >= scan->beg_tid && 296 elm->base.delete_tid <= scan->end_tid && 297 (elm->base.create_tid - scan->beg_tid) / scan->mod_tid == 298 (elm->base.delete_tid - scan->beg_tid) / scan->mod_tid) { 299 return(1); 300 } 301 } 302 return(0); 303 } 304 305 /* 306 * Dangling inodes can occur if processes are holding open descriptors on 307 * deleted files as-of when a machine crashes. When we find one simply 308 * acquire the inode and release it. The inode handling code will then 309 * do the right thing. 310 */ 311 static 312 void 313 prune_check_nlinks(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm) 314 { 315 hammer_inode_t ip; 316 int error; 317 318 if (elm->base.rec_type != HAMMER_RECTYPE_INODE) 319 return; 320 if (elm->base.delete_tid != 0) 321 return; 322 if (hammer_btree_extract(cursor, HAMMER_CURSOR_GET_DATA)) 323 return; 324 if (cursor->data->inode.nlinks) 325 return; 326 hammer_cursor_downgrade(cursor); 327 ip = hammer_get_inode(cursor->trans, NULL, elm->base.obj_id, 328 HAMMER_MAX_TID, 329 elm->base.localization & HAMMER_LOCALIZE_PSEUDOFS_MASK, 330 0, &error); 331 if (ip) { 332 if (hammer_debug_general & 0x0001) { 333 hdkprintf("pruning disconnected inode %016llx\n", 334 (long long)elm->base.obj_id); 335 } 336 hammer_rel_inode(ip, 0); 337 hammer_inode_waitreclaims(cursor->trans); 338 } else { 339 hkprintf("unable to prune disconnected inode %016llx\n", 340 (long long)elm->base.obj_id); 341 } 342 } 343 344 #if 0 345 346 /* 347 * NOTE: THIS CODE HAS BEEN REMOVED! Pruning no longer attempts to realign 348 * adjacent records because it seriously interferes with every 349 * mirroring algorithm I could come up with. 350 * 351 * This means that historical accesses beyond the first snapshot 352 * softlink should be on snapshot boundaries only. Historical 353 * accesses from "now" to the first snapshot softlink continue to 354 * be fine-grained. 355 * 356 * NOTE: It also looks like there's a bug in the removed code. It is believed 357 * that create_tid can sometimes get set to 0xffffffffffffffff. Just as 358 * well we no longer try to do this fancy shit. Probably the attempt to 359 * correct the rhb is blowing up the cursor's indexing or addressing mapping. 360 * 361 * Align the record to cover any gaps created through the deletion of 362 * records within the pruning space. If we were to just delete the records 363 * there would be gaps which in turn would cause a snapshot that is NOT on 364 * a pruning boundary to appear corrupt to the user. Forcing alignment 365 * of the create_tid and delete_tid for retained records 'reconnects' 366 * the previously contiguous space, making it contiguous again after the 367 * deletions. 368 * 369 * The use of a reverse iteration allows us to safely align the records and 370 * related elements without creating temporary overlaps. XXX we should 371 * add ordering dependancies for record buffers to guarantee consistency 372 * during recovery. 373 */ 374 static int 375 realign_prune(struct hammer_ioc_prune *prune, 376 hammer_cursor_t cursor, int realign_cre, int realign_del) 377 { 378 struct hammer_ioc_prune_elm *scan; 379 hammer_btree_elm_t elm; 380 hammer_tid_t delta; 381 hammer_tid_t tid; 382 int error; 383 384 hammer_cursor_downgrade(cursor); 385 386 elm = &cursor->node->ondisk->elms[cursor->index]; 387 ++prune->stat_realignments; 388 389 /* 390 * Align the create_tid. By doing a reverse iteration we guarantee 391 * that all records after our current record have already been 392 * aligned, allowing us to safely correct the right-hand-boundary 393 * (because no record to our right is otherwise exactly matching 394 * will have a create_tid to the left of our aligned create_tid). 395 */ 396 error = 0; 397 if (realign_cre >= 0) { 398 scan = &prune->elms[realign_cre]; 399 400 delta = (elm->leaf.base.create_tid - scan->beg_tid) % 401 scan->mod_tid; 402 if (delta) { 403 tid = elm->leaf.base.create_tid - delta + scan->mod_tid; 404 405 /* can EDEADLK */ 406 error = hammer_btree_correct_rhb(cursor, tid + 1); 407 if (error == 0) { 408 error = hammer_btree_extract(cursor, 409 HAMMER_CURSOR_GET_LEAF); 410 } 411 if (error == 0) { 412 /* can EDEADLK */ 413 error = hammer_cursor_upgrade(cursor); 414 } 415 if (error == 0) { 416 hammer_modify_node(cursor->trans, cursor->node, 417 &elm->leaf.base.create_tid, 418 sizeof(elm->leaf.base.create_tid)); 419 elm->leaf.base.create_tid = tid; 420 hammer_modify_node_done(cursor->node); 421 } 422 } 423 } 424 425 /* 426 * Align the delete_tid. This only occurs if the record is historical 427 * was deleted at some point. Realigning the delete_tid does not 428 * move the record within the B-Tree but may cause it to temporarily 429 * overlap a record that has not yet been pruned. 430 */ 431 if (error == 0 && realign_del >= 0) { 432 scan = &prune->elms[realign_del]; 433 434 delta = (elm->leaf.base.delete_tid - scan->beg_tid) % 435 scan->mod_tid; 436 if (delta) { 437 error = hammer_btree_extract(cursor, 438 HAMMER_CURSOR_GET_LEAF); 439 if (error == 0) { 440 hammer_modify_node(cursor->trans, cursor->node, 441 &elm->leaf.base.delete_tid, 442 sizeof(elm->leaf.base.delete_tid)); 443 elm->leaf.base.delete_tid = 444 elm->leaf.base.delete_tid - 445 delta + scan->mod_tid; 446 hammer_modify_node_done(cursor->node); 447 } 448 } 449 } 450 return (error); 451 } 452 453 #endif 454