1 /*        $NetBSD: chfs_nodeops.c,v 1.5 2021/12/07 21:37:37 andvar Exp $        */
2 
3 /*-
4  * Copyright (c) 2010 Department of Software Engineering,
5  *                        University of Szeged, Hungary
6  * Copyright (C) 2010 David Tengeri <dtengeri@inf.u-szeged.hu>
7  * Copyright (C) 2010 Tamas Toth <ttoth@inf.u-szeged.hu>
8  * Copyright (C) 2010 Adam Hoka <ahoka@NetBSD.org>
9  * All rights reserved.
10  *
11  * This code is derived from software contributed to The NetBSD Foundation
12  * by the Department of Software Engineering, University of Szeged, Hungary
13  *
14  * Redistribution and use in source and binary forms, with or without
15  * modification, are permitted provided that the following conditions
16  * are met:
17  * 1. Redistributions of source code must retain the above copyright
18  *    notice, this list of conditions and the following disclaimer.
19  * 2. Redistributions in binary form must reproduce the above copyright
20  *    notice, this list of conditions and the following disclaimer in the
21  *    documentation and/or other materials provided with the distribution.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
26  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
28  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
29  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
30  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
31  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include "chfs.h"
37 
38 /*
39  * chfs_update_eb_dirty - updates dirty and free space, first and
40  *                                  last node references
41  * Returns zero in case of success, 1 in case of fail.
42  */
43 int
chfs_update_eb_dirty(struct chfs_mount * chmp,struct chfs_eraseblock * cheb,uint32_t size)44 chfs_update_eb_dirty(struct chfs_mount *chmp,
45     struct chfs_eraseblock *cheb, uint32_t size)
46 {
47           KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
48           KASSERT(!mutex_owned(&chmp->chm_lock_sizes));
49 
50           if (!size)
51                     return 0;
52 
53           if (size > cheb->free_size) {
54                     chfs_err("free_size (%d) is less than dirty space (%d) "
55                         "on block (%d)\n", cheb->free_size, size, cheb->lnr);
56                     return 1;
57           }
58           mutex_enter(&chmp->chm_lock_sizes);
59           chfs_change_size_free(chmp, cheb, -size);
60           chfs_change_size_dirty(chmp, cheb, size);
61           mutex_exit(&chmp->chm_lock_sizes);
62           return 0;
63 }
64 
65 /*
66  * chfs_add_node_to_list - adds a data node ref to vnode cache's dnode list
67  * This function inserts a data node ref to the list of vnode cache.
68  * The list is sorted by data node's lnr and offset.
69  */
70 void
chfs_add_node_to_list(struct chfs_mount * chmp,struct chfs_vnode_cache * vc,struct chfs_node_ref * new,struct chfs_node_ref ** list)71 chfs_add_node_to_list(struct chfs_mount *chmp,
72     struct chfs_vnode_cache *vc,
73     struct chfs_node_ref *new, struct chfs_node_ref **list)
74 {
75           KASSERT(mutex_owned(&chmp->chm_lock_vnocache));
76 
77           struct chfs_node_ref *nextref = *list;
78           struct chfs_node_ref *prevref = NULL;
79 
80           while (nextref && nextref != (struct chfs_node_ref *)vc &&
81               (nextref->nref_lnr <= new->nref_lnr)) {
82                     if (nextref->nref_lnr == new->nref_lnr) {
83                               while (nextref && nextref !=
84                                   (struct chfs_node_ref *)vc &&
85                                   (CHFS_GET_OFS(nextref->nref_offset) <
86                                         CHFS_GET_OFS(new->nref_offset))) {
87                                         prevref = nextref;
88                                         nextref = nextref->nref_next;
89                               }
90                               break;
91                     }
92                     prevref = nextref;
93                     nextref = nextref->nref_next;
94           }
95 
96           if (nextref && nextref != (struct chfs_node_ref *)vc &&
97               nextref->nref_lnr == new->nref_lnr &&
98               CHFS_GET_OFS(nextref->nref_offset) ==
99               CHFS_GET_OFS(new->nref_offset)) {
100                     new->nref_next = nextref->nref_next;
101                     chfs_mark_node_obsolete(chmp, nextref);
102           } else {
103                     new->nref_next = nextref;
104           }
105 
106           KASSERT(new->nref_next != NULL);
107 
108           if (prevref) {
109                     prevref->nref_next = new;
110           } else {
111                     *list = new;
112           }
113 }
114 
115 /*
116  * chfs_remove_node_from_list - removes a node from a list
117  * Usually used for removing data nodes.
118  */
119 void
chfs_remove_node_from_list(struct chfs_mount * chmp,struct chfs_vnode_cache * vc,struct chfs_node_ref * old_nref,struct chfs_node_ref ** list)120 chfs_remove_node_from_list(struct chfs_mount *chmp,
121           struct chfs_vnode_cache *vc,
122           struct chfs_node_ref *old_nref, struct chfs_node_ref **list)
123 {
124           KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
125           KASSERT(mutex_owned(&chmp->chm_lock_vnocache));
126 
127           struct chfs_node_ref *tmpnref;
128 
129           if (*list == (struct chfs_node_ref *)vc) {
130                     /* list is empty */
131                     return;
132           }
133 
134           KASSERT(old_nref->nref_next != NULL);
135 
136           if (*list == old_nref) {
137                     *list = old_nref->nref_next;
138           } else {
139                     tmpnref = *list;
140                     while (tmpnref->nref_next &&
141                               tmpnref->nref_next != (struct chfs_node_ref *)vc) {
142                               if (tmpnref->nref_next == old_nref) {
143                                         tmpnref->nref_next = old_nref->nref_next;
144                                         break;
145                               }
146                               tmpnref = tmpnref->nref_next;
147                     }
148           }
149 }
150 
151 /*
152  * chfs_remove_and_obsolete - removes a node from a list and obsoletes the nref
153  * We should use this function carefully on data nodes,
154  * because removing a frag will also obsolete the node ref.
155  */
156 void
chfs_remove_and_obsolete(struct chfs_mount * chmp,struct chfs_vnode_cache * vc,struct chfs_node_ref * old_nref,struct chfs_node_ref ** list)157 chfs_remove_and_obsolete(struct chfs_mount *chmp,
158           struct chfs_vnode_cache *vc,
159           struct chfs_node_ref *old_nref, struct chfs_node_ref **list)
160 {
161           KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
162           KASSERT(mutex_owned(&chmp->chm_lock_vnocache));
163 
164           chfs_remove_node_from_list(chmp, vc, old_nref, list);
165 
166           dbg("[MARK] vno: %llu lnr: %u ofs: %u\n", vc->vno, old_nref->nref_lnr,
167                     old_nref->nref_offset);
168           chfs_mark_node_obsolete(chmp, old_nref);
169 }
170 
171 /* chfs_add_fd_to_inode - adds a directory entry to an inode */
172 void
chfs_add_fd_to_inode(struct chfs_mount * chmp,struct chfs_inode * parent,struct chfs_dirent * new)173 chfs_add_fd_to_inode(struct chfs_mount *chmp,
174     struct chfs_inode *parent, struct chfs_dirent *new)
175 {
176           struct chfs_dirent *fd, *tmpfd;
177 
178           /* update highest version */
179           if (new->version > parent->chvc->highest_version) {
180                     parent->chvc->highest_version = new->version;
181           }
182 
183           TAILQ_FOREACH_SAFE(fd, &parent->dents, fds, tmpfd) {
184                     if (fd->nhash > new->nhash) {
185                               /* insert new before fd */
186                               TAILQ_INSERT_BEFORE(fd, new, fds);
187                               return;
188                     } else if (fd->nhash == new->nhash &&
189                         !strcmp(fd->name, new->name)) {
190                               if (new->version > fd->version) {
191                                         /* replace fd with new */
192                                         TAILQ_INSERT_BEFORE(fd, new, fds);
193                                         TAILQ_REMOVE(&parent->dents, fd, fds);
194                                         if (fd->nref) {
195                                                   mutex_enter(&chmp->chm_lock_vnocache);
196                                                   chfs_remove_and_obsolete(chmp, parent->chvc, fd->nref,
197                                                             &parent->chvc->dirents);
198                                                   mutex_exit(&chmp->chm_lock_vnocache);
199                                         }
200                                         chfs_free_dirent(fd);
201                               } else {
202                                         /* new is older (normally it's not an option) */
203                                         chfs_mark_node_obsolete(chmp, new->nref);
204                                         chfs_free_dirent(new);
205                               }
206                               return;
207                     }
208           }
209           /* if we couldn't fit it elsewhere, lets add to the end */
210           /* FIXME insert tail or insert head? */
211           TAILQ_INSERT_HEAD(&parent->dents, new, fds);
212 }
213 
214 
215 /* chfs_add_vnode_ref_to_vc - adds a vnode info to the vnode cache */
216 void
chfs_add_vnode_ref_to_vc(struct chfs_mount * chmp,struct chfs_vnode_cache * vc,struct chfs_node_ref * new)217 chfs_add_vnode_ref_to_vc(struct chfs_mount *chmp,
218     struct chfs_vnode_cache *vc, struct chfs_node_ref *new)
219 {
220           KASSERT(mutex_owned(&chmp->chm_lock_vnocache));
221           struct chfs_node_ref *nref;
222 
223           /* store only the last one, drop the others */
224           while (vc->v != (struct chfs_node_ref *)vc) {
225                     nref = vc->v;
226                     chfs_remove_and_obsolete(chmp, vc, nref, &vc->v);
227           }
228 
229           new->nref_next = (struct chfs_node_ref *)vc;
230           vc->v = new;
231 }
232 
233 /* chfs_nref_next - step to the next in-memory nref */
234 struct chfs_node_ref *
chfs_nref_next(struct chfs_node_ref * nref)235 chfs_nref_next(struct chfs_node_ref *nref)
236 {
237           nref++;
238           if (nref->nref_lnr == REF_LINK_TO_NEXT) {
239                     /* end of chain */
240                     if (!nref->nref_next)
241                               return NULL;
242 
243                     /* link to the next block */
244                     nref = nref->nref_next;
245           }
246           /* end of chain */
247           if (nref->nref_lnr == REF_EMPTY_NODE)
248                     return NULL;
249 
250           return nref;
251 }
252 
253 /* chfs_nref_len - calculates the length of an nref */
254 int
chfs_nref_len(struct chfs_mount * chmp,struct chfs_eraseblock * cheb,struct chfs_node_ref * nref)255 chfs_nref_len(struct chfs_mount *chmp,
256     struct chfs_eraseblock *cheb, struct chfs_node_ref *nref)
257 {
258           struct chfs_node_ref *next;
259 
260           KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
261 
262           if (!cheb)
263                     cheb = &chmp->chm_blocks[nref->nref_lnr];
264 
265           next = chfs_nref_next(nref);
266 
267           if (!next) {
268                     return chmp->chm_ebh->eb_size - cheb->free_size -
269                         CHFS_GET_OFS(nref->nref_offset);
270           }
271           return CHFS_GET_OFS(next->nref_offset) -
272               CHFS_GET_OFS(nref->nref_offset);
273 }
274 
275 /* chfs_mark_node_obsolete - marks a node as obsolete */
276 void
chfs_mark_node_obsolete(struct chfs_mount * chmp,struct chfs_node_ref * nref)277 chfs_mark_node_obsolete(struct chfs_mount *chmp,
278     struct chfs_node_ref *nref)
279 {
280           int len;
281           struct chfs_eraseblock *cheb;
282 
283           KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
284 
285           KASSERT(!CHFS_REF_OBSOLETE(nref));
286 
287           KASSERT(nref->nref_lnr <= chmp->chm_ebh->peb_nr);
288           cheb = &chmp->chm_blocks[nref->nref_lnr];
289 
290 #ifdef DIAGNOSTIC
291           if (cheb->used_size + cheb->free_size + cheb->dirty_size +
292               cheb->unchecked_size + cheb->wasted_size != chmp->chm_ebh->eb_size) {
293                     dbg("eraseblock leak detected!\nused: %u\nfree: %u\n"
294                         "dirty: %u\nunchecked: %u\nwasted: %u\ntotal: %u\nshould be: %zu\n",
295                         cheb->used_size, cheb->free_size, cheb->dirty_size,
296                         cheb->unchecked_size, cheb->wasted_size, cheb->used_size + cheb->free_size +
297                         cheb->dirty_size + cheb->unchecked_size + cheb->wasted_size,
298                         chmp->chm_ebh->eb_size);
299           }
300 #endif
301 
302           len = chfs_nref_len(chmp, cheb, nref);
303 
304           mutex_enter(&chmp->chm_lock_sizes);
305 
306           if (CHFS_REF_FLAGS(nref) == CHFS_UNCHECKED_NODE_MASK) {
307                     chfs_change_size_unchecked(chmp, cheb, -len);
308           } else {
309                     chfs_change_size_used(chmp, cheb, -len);
310 
311                     KASSERT(cheb->used_size <= chmp->chm_ebh->eb_size);
312           }
313           chfs_change_size_dirty(chmp, cheb, len);
314 
315 #ifdef DIAGNOSTIC
316           if (cheb->used_size + cheb->free_size + cheb->dirty_size +
317               cheb->unchecked_size + cheb->wasted_size != chmp->chm_ebh->eb_size) {
318                     panic("eraseblock leak detected!\nused: %u\nfree: %u\n"
319                         "dirty: %u\nunchecked: %u\nwasted: %u\ntotal: %u\nshould be: %zu\n",
320                         cheb->used_size, cheb->free_size, cheb->dirty_size,
321                         cheb->unchecked_size, cheb->wasted_size, cheb->used_size + cheb->free_size +
322                         cheb->dirty_size + cheb->unchecked_size + cheb->wasted_size,
323                         chmp->chm_ebh->eb_size);
324           }
325 #endif
326           nref->nref_offset = CHFS_GET_OFS(nref->nref_offset) |
327               CHFS_OBSOLETE_NODE_MASK;
328 
329           if (chmp->chm_flags & CHFS_MP_FLAG_SCANNING) {
330                     /*Scan is in progress, do nothing now*/
331                     mutex_exit(&chmp->chm_lock_sizes);
332                     return;
333           }
334 
335           if (cheb == chmp->chm_nextblock) {
336                     dbg("Not moving nextblock to dirty/erase_pending list\n");
337           } else if (!cheb->used_size && !cheb->unchecked_size) {
338                     if (cheb == chmp->chm_gcblock) {
339                               dbg("gcblock is completely dirtied\n");
340                               chmp->chm_gcblock = NULL;
341                     } else {
342                               /* remove from a tailq, but we don't know which tailq contains this cheb
343                                * so we remove it from the dirty list now */
344                               //TAILQ_REMOVE(&chmp->chm_dirty_queue, cheb, queue);
345                               int removed = 0;
346                               struct chfs_eraseblock *eb, *tmpeb;
347                               //XXX ugly code
348                               TAILQ_FOREACH_SAFE(eb, &chmp->chm_free_queue, queue, tmpeb) {
349                                         if (eb == cheb) {
350                                                   TAILQ_REMOVE(&chmp->chm_free_queue, cheb, queue);
351                                                   removed = 1;
352                                                   break;
353                                         }
354                               }
355                               if (removed == 0) {
356                                         TAILQ_FOREACH_SAFE(eb, &chmp->chm_dirty_queue, queue, tmpeb) {
357                                                   if (eb == cheb) {
358                                                             TAILQ_REMOVE(&chmp->chm_dirty_queue, cheb, queue);
359                                                             removed = 1;
360                                                             break;
361                                                   }
362                                         }
363                               }
364                               if (removed == 0) {
365                                         TAILQ_FOREACH_SAFE(eb, &chmp->chm_very_dirty_queue, queue, tmpeb) {
366                                                   if (eb == cheb) {
367                                                             TAILQ_REMOVE(&chmp->chm_very_dirty_queue, cheb, queue);
368                                                             removed = 1;
369                                                             break;
370                                                   }
371                                         }
372                               }
373                               if (removed == 0) {
374                                         TAILQ_FOREACH_SAFE(eb, &chmp->chm_clean_queue, queue, tmpeb) {
375                                                   if (eb == cheb) {
376                                                             TAILQ_REMOVE(&chmp->chm_clean_queue, cheb, queue);
377                                                             removed = 1;
378                                                             break;
379                                                   }
380                                         }
381                               }
382                     }
383                     if (chmp->chm_wbuf_len) {
384                               dbg("Adding block to erasable pending wbuf queue\n");
385                               TAILQ_INSERT_TAIL(&chmp->chm_erasable_pending_wbuf_queue,
386                                   cheb, queue);
387                     } else {
388                               TAILQ_INSERT_TAIL(&chmp->chm_erase_pending_queue,
389                                   cheb, queue);
390                               chmp->chm_nr_erasable_blocks++;
391                     }
392                     chfs_remap_leb(chmp);
393           } else if (cheb == chmp->chm_gcblock) {
394                     dbg("Not moving gcblock to dirty list\n");
395           } else if (cheb->dirty_size > MAX_DIRTY_TO_CLEAN &&
396               cheb->dirty_size - len <= MAX_DIRTY_TO_CLEAN) {
397                     dbg("Freshly dirtied, remove it from clean queue and "
398                         "add it to dirty\n");
399                     TAILQ_REMOVE(&chmp->chm_clean_queue, cheb, queue);
400                     TAILQ_INSERT_TAIL(&chmp->chm_dirty_queue, cheb, queue);
401           } else if (VERY_DIRTY(chmp, cheb->dirty_size) &&
402               !VERY_DIRTY(chmp, cheb->dirty_size - len)) {
403                     dbg("Becomes now very dirty, remove it from dirty "
404                         "queue and add it to very dirty\n");
405                     TAILQ_REMOVE(&chmp->chm_dirty_queue, cheb, queue);
406                     TAILQ_INSERT_TAIL(&chmp->chm_very_dirty_queue, cheb, queue);
407           } else {
408                     dbg("Leave cheb where it is\n");
409           }
410           mutex_exit(&chmp->chm_lock_sizes);
411           return;
412 }
413 
414 /*
415  * chfs_close_eraseblock - close an eraseblock
416  *
417  * This function close the physical chain of the nodes on the eraseblock,
418  * convert its free size to dirty and add it to clean, dirty or very dirty list.
419  */
420 int
chfs_close_eraseblock(struct chfs_mount * chmp,struct chfs_eraseblock * cheb)421 chfs_close_eraseblock(struct chfs_mount *chmp,
422     struct chfs_eraseblock *cheb)
423 {
424           uint32_t offset;
425           struct chfs_node_ref *nref;
426 
427           KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
428 
429           offset = chmp->chm_ebh->eb_size - cheb->free_size;
430 
431           // Close the chain
432           nref = chfs_alloc_node_ref(cheb);
433           if (!nref)
434                     return ENOMEM;
435 
436           nref->nref_next = NULL;
437           nref->nref_offset = offset;
438 
439           // Mark space as dirty
440           chfs_update_eb_dirty(chmp, cheb, cheb->free_size);
441 
442           if (cheb->dirty_size < MAX_DIRTY_TO_CLEAN) {
443                     TAILQ_INSERT_TAIL(&chmp->chm_clean_queue, cheb, queue);
444           } else if (VERY_DIRTY(chmp, cheb->dirty_size)) {
445                     TAILQ_INSERT_TAIL(&chmp->chm_very_dirty_queue, cheb, queue);
446           } else {
447                     TAILQ_INSERT_TAIL(&chmp->chm_dirty_queue, cheb, queue);
448           }
449           return 0;
450 }
451 
452 /*
453  * chfs_reserve_space_normal -
454  * checks available space and calls chfs_reserve_space
455  * used during writing
456  */
457 int
chfs_reserve_space_normal(struct chfs_mount * chmp,uint32_t size,int prio)458 chfs_reserve_space_normal(struct chfs_mount *chmp, uint32_t size, int prio)
459 {
460           int ret;
461 
462           KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
463 
464           mutex_enter(&chmp->chm_lock_sizes);
465           while (chmp->chm_nr_free_blocks + chmp->chm_nr_erasable_blocks < chmp->chm_resv_blocks_write) {
466                     dbg("free: %d, erasable: %d, resv: %d\n", chmp->chm_nr_free_blocks, chmp->chm_nr_erasable_blocks, chmp->chm_resv_blocks_write);
467                     uint32_t avail, dirty;
468                     if (prio == ALLOC_DELETION && chmp->chm_nr_free_blocks + chmp->chm_nr_erasable_blocks >= chmp->chm_resv_blocks_deletion)
469                               break;
470 
471                     dirty = chmp->chm_dirty_size - chmp->chm_nr_erasable_blocks * chmp->chm_ebh->eb_size + chmp->chm_unchecked_size;
472                     if (dirty < chmp->chm_nospc_dirty) {
473                               dbg("dirty: %u < nospc_dirty: %u\n", dirty, chmp->chm_nospc_dirty);
474                               ret = ENOSPC;
475                               mutex_exit(&chmp->chm_lock_sizes);
476                               goto out;
477                     }
478 
479                     avail = chmp->chm_free_size - (chmp->chm_resv_blocks_write * chmp->chm_ebh->eb_size);
480                     if (size > avail) {
481                               dbg("size: %u > avail: %u\n", size, avail);
482                               ret = ENOSPC;
483                               mutex_exit(&chmp->chm_lock_sizes);
484                               goto out;
485                     }
486 
487                     mutex_exit(&chmp->chm_lock_sizes);
488                     ret = chfs_gcollect_pass(chmp);
489                     mutex_enter(&chmp->chm_lock_sizes);
490 
491                     if (chmp->chm_nr_erasable_blocks ||
492                         !TAILQ_EMPTY(&chmp->chm_erasable_pending_wbuf_queue) ||
493                         ret == EAGAIN) {
494                               ret = chfs_remap_leb(chmp);
495                     }
496 
497                     if (ret) {
498                               mutex_exit(&chmp->chm_lock_sizes);
499                               goto out;
500                     }
501           }
502 
503           mutex_exit(&chmp->chm_lock_sizes);
504           ret = chfs_reserve_space(chmp, size);
505 out:
506           return ret;
507 }
508 
509 
510 /* chfs_reserve_space_gc - tries to reserve space for GC */
511 int
chfs_reserve_space_gc(struct chfs_mount * chmp,uint32_t size)512 chfs_reserve_space_gc(struct chfs_mount *chmp, uint32_t size)
513 {
514           int ret;
515 
516           KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
517 
518           mutex_enter(&chmp->chm_lock_sizes);
519           chfs_remap_leb(chmp);
520 
521           if (size > chmp->chm_free_size) {
522                     dbg("size: %u\n", size);
523                     mutex_exit(&chmp->chm_lock_sizes);
524                     return ENOSPC;
525           }
526 
527           mutex_exit(&chmp->chm_lock_sizes);
528           ret = chfs_reserve_space(chmp, size);
529           return ret;
530 }
531 
532 /*
533  * chfs_reserve_space - finds a block which free size is >= requested size
534  * Returns zero in case of success, error code in case of fail.
535  */
536 int
chfs_reserve_space(struct chfs_mount * chmp,uint32_t size)537 chfs_reserve_space(struct chfs_mount *chmp, uint32_t size)
538 {
539           //TODO define minimum reserved blocks, which is needed for writing
540           //TODO check we have enough free blocks to write
541           //TODO if no: need erase and GC
542 
543           int err;
544           struct chfs_eraseblock *cheb;
545 
546           KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
547           KASSERT(!mutex_owned(&chmp->chm_lock_sizes));
548 
549           cheb = chmp->chm_nextblock;
550           if (cheb && size > cheb->free_size) {
551                     dbg("size: %u > free_size: %u\n", size, cheb->free_size);
552                     /*
553                      * There isn't enough space on this eraseblock, we mark this as
554                      * dirty and close the physical chain of the node refs.
555                      */
556                     //Write out pending data if any
557                     if (chmp->chm_wbuf_len) {
558                               chfs_flush_pending_wbuf(chmp);
559                               //FIXME need goto restart here?
560                     }
561 
562                     while (chmp->chm_wbuf_ofs < chmp->chm_ebh->eb_size) {
563                               dbg("wbuf ofs: %zu - eb_size: %zu\n",
564                                   chmp->chm_wbuf_ofs, chmp->chm_ebh->eb_size);
565                               chfs_flush_pending_wbuf(chmp);
566                     }
567 
568                     if (!(chmp->chm_wbuf_ofs % chmp->chm_ebh->eb_size) && !chmp->chm_wbuf_len)
569                               chmp->chm_wbuf_ofs = 0xffffffff;
570 
571                     err = chfs_close_eraseblock(chmp, cheb);
572                     if (err)
573                               return err;
574 
575                     cheb = NULL;
576           }
577           if (!cheb) {
578                     //get a block for nextblock
579                     if (TAILQ_EMPTY(&chmp->chm_free_queue)) {
580                               // If this succeeds there will be a block on free_queue
581                               dbg("cheb remap (free: %d)\n", chmp->chm_nr_free_blocks);
582                               err = chfs_remap_leb(chmp);
583                               if (err)
584                                         return err;
585                     }
586                     cheb = TAILQ_FIRST(&chmp->chm_free_queue);
587                     TAILQ_REMOVE(&chmp->chm_free_queue, cheb, queue);
588                     chmp->chm_nextblock = cheb;
589                     chmp->chm_nr_free_blocks--;
590           }
591 
592           return 0;
593 }
594 
595