2 * Copyright (c) 2008 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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
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18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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34 * $DragonFly: src/sys/vfs/hammer/hammer_prune.c,v 1.11 2008/07/01 17:30:42 dillon Exp $
40 * Iterate through the specified range of object ids and remove any
41 * deleted records that fall entirely within a prune modulo.
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.
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);
53 hammer_ioc_prune(hammer_transaction_t trans, hammer_inode_t ip,
54 struct hammer_ioc_prune *prune)
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;
64 if (prune->nelms < 0 || prune->nelms > HAMMER_MAX_PRUNE_ELMS)
66 if ((prune->key_beg.localization | prune->key_end.localization) &
67 HAMMER_LOCALIZE_PSEUDOFS_MASK) {
70 if (prune->key_beg.localization > prune->key_end.localization)
72 if (prune->key_beg.localization == prune->key_end.localization) {
73 if (prune->key_beg.obj_id > prune->key_end.obj_id)
75 /* key-space limitations - no check needed */
77 if ((prune->head.flags & HAMMER_IOC_PRUNE_ALL) && prune->nelms)
80 prune->key_cur.localization = prune->key_end.localization +
82 prune->key_cur.obj_id = prune->key_end.obj_id;
83 prune->key_cur.key = HAMMER_MAX_KEY;
86 * Copy element array from userland
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)
93 prune->elms = copy_elms;
96 * Scan backwards. Retries typically occur if a deadlock is detected.
99 error = hammer_init_cursor(trans, &cursor, NULL, NULL);
101 hammer_done_cursor(&cursor);
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;
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;
121 cursor.flags |= HAMMER_CURSOR_END_INCLUSIVE;
122 cursor.flags |= HAMMER_CURSOR_BACKEND;
125 * This flag allows the B-Tree code to clean up loose ends.
127 cursor.flags |= HAMMER_CURSOR_PRUNING;
129 hammer_sync_lock_sh(trans);
130 error = hammer_btree_last(&cursor);
136 elm = &cursor.node->ondisk->elms[cursor.index].leaf;
137 prune->key_cur = elm->base;
140 * Yield to more important tasks
142 if ((error = hammer_signal_check(trans->hmp)) != 0)
144 if (trans->hmp->sync_lock.wanted) {
145 hammer_sync_unlock(trans);
146 tsleep(trans, 0, "hmrslo", hz / 10);
147 hammer_sync_lock_sh(trans);
149 if (hammer_flusher_meta_limit(trans->hmp) ||
150 hammer_flusher_undo_exhausted(trans, 2)) {
155 if (prune->stat_oldest_tid > elm->base.create_tid)
156 prune->stat_oldest_tid = elm->base.create_tid;
158 if (hammer_debug_general & 0x0200) {
159 kprintf("check %016llx %016llx cre=%016llx del=%016llx\n",
162 elm->base.create_tid,
163 elm->base.delete_tid);
166 if (prune_should_delete(prune, elm)) {
167 if (hammer_debug_general & 0x0200) {
168 kprintf("check %016llx %016llx: DELETE\n",
169 elm->base.obj_id, elm->base.key);
173 * NOTE: This can return EDEADLK
175 * Acquiring the sync lock guarantees that the
176 * operation will not cross a synchronization
177 * boundary (see the flusher).
179 isdir = (elm->base.rec_type == HAMMER_RECTYPE_DIRENTRY);
181 error = hammer_delete_at_cursor(&cursor,
187 ++prune->stat_dirrecords;
189 ++prune->stat_rawrecords;
192 * The current record might now be the one after
193 * the one we deleted, set ATEDISK to force us
194 * to skip it (since we are iterating backwards).
196 cursor.flags |= HAMMER_CURSOR_ATEDISK;
199 * Nothing to delete, but we may have to check other
202 prune_check_nlinks(&cursor, elm);
203 cursor.flags |= HAMMER_CURSOR_ATEDISK;
204 if (hammer_debug_general & 0x0100) {
205 kprintf("check %016llx %016llx: SKIP\n",
206 elm->base.obj_id, elm->base.key);
209 ++prune->stat_scanrecords;
210 error = hammer_btree_iterate_reverse(&cursor);
212 hammer_sync_unlock(trans);
215 hammer_done_cursor(&cursor);
216 if (error == EWOULDBLOCK) {
217 hammer_flusher_sync(trans->hmp);
220 if (error == EDEADLK)
222 if (error == EINTR) {
223 prune->head.flags |= HAMMER_IOC_HEAD_INTR;
227 prune->key_cur.localization &= HAMMER_LOCALIZE_MASK;
228 prune->elms = user_elms;
229 kfree(copy_elms, M_TEMP);
234 * Check pruning list. The list must be sorted in descending order.
236 * Return non-zero if the record should be deleted.
239 prune_should_delete(struct hammer_ioc_prune *prune, hammer_btree_leaf_elm_t elm)
241 struct hammer_ioc_prune_elm *scan;
245 * If pruning everything remove all records with a non-zero
248 if (prune->head.flags & HAMMER_IOC_PRUNE_ALL) {
249 if (elm->base.delete_tid != 0)
254 for (i = 0; i < prune->nelms; ++i) {
255 scan = &prune->elms[i];
258 * Check for loop termination.
260 if (elm->base.create_tid >= scan->end_tid ||
261 elm->base.delete_tid > scan->end_tid) {
266 * Determine if we can delete the record.
268 if (elm->base.delete_tid &&
269 elm->base.create_tid >= scan->beg_tid &&
270 elm->base.delete_tid <= scan->end_tid &&
271 (elm->base.create_tid - scan->beg_tid) / scan->mod_tid ==
272 (elm->base.delete_tid - scan->beg_tid) / scan->mod_tid) {
280 * Dangling inodes can occur if processes are holding open descriptors on
281 * deleted files as-of when a machine crashes. When we find one simply
282 * acquire the inode and release it. The inode handling code will then
283 * do the right thing.
287 prune_check_nlinks(hammer_cursor_t cursor, hammer_btree_leaf_elm_t elm)
292 if (elm->base.rec_type != HAMMER_RECTYPE_INODE)
294 if (elm->base.delete_tid != 0)
296 if (hammer_btree_extract(cursor, HAMMER_CURSOR_GET_DATA))
298 if (cursor->data->inode.nlinks)
300 hammer_cursor_downgrade(cursor);
301 hammer_sync_unlock(cursor->trans);
302 ip = hammer_get_inode(cursor->trans, NULL, elm->base.obj_id,
304 elm->base.localization & HAMMER_LOCALIZE_PSEUDOFS_MASK,
307 kprintf("pruning disconnected inode %016llx\n",
309 hammer_rel_inode(ip, 0);
311 kprintf("unable to prune disconnected inode %016llx\n",
314 hammer_sync_lock_sh(cursor->trans);
320 * NOTE: THIS CODE HAS BEEN REMOVED! Pruning no longer attempts to realign
321 * adjacent records because it seriously interferes with every
322 * mirroring algorithm I could come up with.
324 * This means that historical accesses beyond the first snapshot
325 * softlink should be on snapshot boundaries only. Historical
326 * accesses from "now" to the first snapshot softlink continue to
329 * NOTE: It also looks like there's a bug in the removed code. It is believed
330 * that create_tid can sometimes get set to 0xffffffffffffffff. Just as
331 * well we no longer try to do this fancy shit. Probably the attempt to
332 * correct the rhb is blowing up the cursor's indexing or addressing mapping.
334 * Align the record to cover any gaps created through the deletion of
335 * records within the pruning space. If we were to just delete the records
336 * there would be gaps which in turn would cause a snapshot that is NOT on
337 * a pruning boundary to appear corrupt to the user. Forcing alignment
338 * of the create_tid and delete_tid for retained records 'reconnects'
339 * the previously contiguous space, making it contiguous again after the
342 * The use of a reverse iteration allows us to safely align the records and
343 * related elements without creating temporary overlaps. XXX we should
344 * add ordering dependancies for record buffers to guarantee consistency
348 realign_prune(struct hammer_ioc_prune *prune,
349 hammer_cursor_t cursor, int realign_cre, int realign_del)
351 struct hammer_ioc_prune_elm *scan;
352 hammer_btree_elm_t elm;
357 hammer_cursor_downgrade(cursor);
359 elm = &cursor->node->ondisk->elms[cursor->index];
360 ++prune->stat_realignments;
363 * Align the create_tid. By doing a reverse iteration we guarantee
364 * that all records after our current record have already been
365 * aligned, allowing us to safely correct the right-hand-boundary
366 * (because no record to our right is otherwise exactly matching
367 * will have a create_tid to the left of our aligned create_tid).
370 if (realign_cre >= 0) {
371 scan = &prune->elms[realign_cre];
373 delta = (elm->leaf.base.create_tid - scan->beg_tid) %
376 tid = elm->leaf.base.create_tid - delta + scan->mod_tid;
379 error = hammer_btree_correct_rhb(cursor, tid + 1);
381 error = hammer_btree_extract(cursor,
382 HAMMER_CURSOR_GET_LEAF);
386 error = hammer_cursor_upgrade(cursor);
389 hammer_modify_node(cursor->trans, cursor->node,
390 &elm->leaf.base.create_tid,
391 sizeof(elm->leaf.base.create_tid));
392 elm->leaf.base.create_tid = tid;
393 hammer_modify_node_done(cursor->node);
399 * Align the delete_tid. This only occurs if the record is historical
400 * was deleted at some point. Realigning the delete_tid does not
401 * move the record within the B-Tree but may cause it to temporarily
402 * overlap a record that has not yet been pruned.
404 if (error == 0 && realign_del >= 0) {
405 scan = &prune->elms[realign_del];
407 delta = (elm->leaf.base.delete_tid - scan->beg_tid) %
410 error = hammer_btree_extract(cursor,
411 HAMMER_CURSOR_GET_LEAF);
413 hammer_modify_node(cursor->trans, cursor->node,
414 &elm->leaf.base.delete_tid,
415 sizeof(elm->leaf.base.delete_tid));
416 elm->leaf.base.delete_tid =
417 elm->leaf.base.delete_tid -
418 delta + scan->mod_tid;
419 hammer_modify_node_done(cursor->node);