xref: /dragonfly/sys/vfs/hammer2/hammer2_vfsops.c (revision 820c5b08)
1 /*
2  * Copyright (c) 2011-2015 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  * by Daniel Flores (GSOC 2013 - mentored by Matthew Dillon, compression)
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  *
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in
16  *    the documentation and/or other materials provided with the
17  *    distribution.
18  * 3. Neither the name of The DragonFly Project nor the names of its
19  *    contributors may be used to endorse or promote products derived
20  *    from this software without specific, prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
23  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
24  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
25  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
26  * COPYRIGHT HOLDERS OR CONTRIBUTORS 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 OUT
32  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/kernel.h>
38 #include <sys/nlookup.h>
39 #include <sys/vnode.h>
40 #include <sys/mount.h>
41 #include <sys/fcntl.h>
42 #include <sys/buf.h>
43 #include <sys/uuid.h>
44 #include <sys/vfsops.h>
45 #include <sys/sysctl.h>
46 #include <sys/socket.h>
47 #include <sys/objcache.h>
48 
49 #include <sys/proc.h>
50 #include <sys/namei.h>
51 #include <sys/mountctl.h>
52 #include <sys/dirent.h>
53 #include <sys/uio.h>
54 
55 #include <sys/mutex.h>
56 #include <sys/mutex2.h>
57 
58 #include "hammer2.h"
59 #include "hammer2_disk.h"
60 #include "hammer2_mount.h"
61 #include "hammer2_lz4.h"
62 
63 #include "zlib/hammer2_zlib.h"
64 
65 #define REPORT_REFS_ERRORS 1	/* XXX remove me */
66 
67 MALLOC_DEFINE(M_OBJCACHE, "objcache", "Object Cache");
68 
69 struct hammer2_sync_info {
70 	int error;
71 	int waitfor;
72 };
73 
74 TAILQ_HEAD(hammer2_mntlist, hammer2_dev);
75 TAILQ_HEAD(hammer2_pfslist, hammer2_pfs);
76 static struct hammer2_mntlist hammer2_mntlist;
77 static struct hammer2_pfslist hammer2_pfslist;
78 static struct lock hammer2_mntlk;
79 
80 int hammer2_debug;
81 int hammer2_cluster_enable = 1;
82 int hammer2_hardlink_enable = 1;
83 int hammer2_flush_pipe = 100;
84 int hammer2_synchronous_flush = 1;
85 int hammer2_dio_count;
86 long hammer2_limit_dirty_chains;
87 long hammer2_count_modified_chains;
88 long hammer2_iod_file_read;
89 long hammer2_iod_meta_read;
90 long hammer2_iod_indr_read;
91 long hammer2_iod_fmap_read;
92 long hammer2_iod_volu_read;
93 long hammer2_iod_file_write;
94 long hammer2_iod_file_wembed;
95 long hammer2_iod_file_wzero;
96 long hammer2_iod_file_wdedup;
97 long hammer2_iod_meta_write;
98 long hammer2_iod_indr_write;
99 long hammer2_iod_fmap_write;
100 long hammer2_iod_volu_write;
101 long hammer2_ioa_file_read;
102 long hammer2_ioa_meta_read;
103 long hammer2_ioa_indr_read;
104 long hammer2_ioa_fmap_read;
105 long hammer2_ioa_volu_read;
106 long hammer2_ioa_fmap_write;
107 long hammer2_ioa_file_write;
108 long hammer2_ioa_meta_write;
109 long hammer2_ioa_indr_write;
110 long hammer2_ioa_volu_write;
111 
112 MALLOC_DECLARE(M_HAMMER2_CBUFFER);
113 MALLOC_DEFINE(M_HAMMER2_CBUFFER, "HAMMER2-compbuffer",
114 		"Buffer used for compression.");
115 
116 MALLOC_DECLARE(M_HAMMER2_DEBUFFER);
117 MALLOC_DEFINE(M_HAMMER2_DEBUFFER, "HAMMER2-decompbuffer",
118 		"Buffer used for decompression.");
119 
120 SYSCTL_NODE(_vfs, OID_AUTO, hammer2, CTLFLAG_RW, 0, "HAMMER2 filesystem");
121 
122 SYSCTL_INT(_vfs_hammer2, OID_AUTO, debug, CTLFLAG_RW,
123 	   &hammer2_debug, 0, "");
124 SYSCTL_INT(_vfs_hammer2, OID_AUTO, cluster_enable, CTLFLAG_RW,
125 	   &hammer2_cluster_enable, 0, "");
126 SYSCTL_INT(_vfs_hammer2, OID_AUTO, hardlink_enable, CTLFLAG_RW,
127 	   &hammer2_hardlink_enable, 0, "");
128 SYSCTL_INT(_vfs_hammer2, OID_AUTO, flush_pipe, CTLFLAG_RW,
129 	   &hammer2_flush_pipe, 0, "");
130 SYSCTL_INT(_vfs_hammer2, OID_AUTO, synchronous_flush, CTLFLAG_RW,
131 	   &hammer2_synchronous_flush, 0, "");
132 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, limit_dirty_chains, CTLFLAG_RW,
133 	   &hammer2_limit_dirty_chains, 0, "");
134 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, count_modified_chains, CTLFLAG_RW,
135 	   &hammer2_count_modified_chains, 0, "");
136 SYSCTL_INT(_vfs_hammer2, OID_AUTO, dio_count, CTLFLAG_RD,
137 	   &hammer2_dio_count, 0, "");
138 
139 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_file_read, CTLFLAG_RW,
140 	   &hammer2_iod_file_read, 0, "");
141 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_meta_read, CTLFLAG_RW,
142 	   &hammer2_iod_meta_read, 0, "");
143 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_indr_read, CTLFLAG_RW,
144 	   &hammer2_iod_indr_read, 0, "");
145 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_fmap_read, CTLFLAG_RW,
146 	   &hammer2_iod_fmap_read, 0, "");
147 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_volu_read, CTLFLAG_RW,
148 	   &hammer2_iod_volu_read, 0, "");
149 
150 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_file_write, CTLFLAG_RW,
151 	   &hammer2_iod_file_write, 0, "");
152 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_file_wembed, CTLFLAG_RW,
153 	   &hammer2_iod_file_wembed, 0, "");
154 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_file_wzero, CTLFLAG_RW,
155 	   &hammer2_iod_file_wzero, 0, "");
156 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_file_wdedup, CTLFLAG_RW,
157 	   &hammer2_iod_file_wdedup, 0, "");
158 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_meta_write, CTLFLAG_RW,
159 	   &hammer2_iod_meta_write, 0, "");
160 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_indr_write, CTLFLAG_RW,
161 	   &hammer2_iod_indr_write, 0, "");
162 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_fmap_write, CTLFLAG_RW,
163 	   &hammer2_iod_fmap_write, 0, "");
164 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, iod_volu_write, CTLFLAG_RW,
165 	   &hammer2_iod_volu_write, 0, "");
166 
167 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, ioa_file_read, CTLFLAG_RW,
168 	   &hammer2_ioa_file_read, 0, "");
169 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, ioa_meta_read, CTLFLAG_RW,
170 	   &hammer2_ioa_meta_read, 0, "");
171 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, ioa_indr_read, CTLFLAG_RW,
172 	   &hammer2_ioa_indr_read, 0, "");
173 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, ioa_fmap_read, CTLFLAG_RW,
174 	   &hammer2_ioa_fmap_read, 0, "");
175 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, ioa_volu_read, CTLFLAG_RW,
176 	   &hammer2_ioa_volu_read, 0, "");
177 
178 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, ioa_file_write, CTLFLAG_RW,
179 	   &hammer2_ioa_file_write, 0, "");
180 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, ioa_meta_write, CTLFLAG_RW,
181 	   &hammer2_ioa_meta_write, 0, "");
182 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, ioa_indr_write, CTLFLAG_RW,
183 	   &hammer2_ioa_indr_write, 0, "");
184 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, ioa_fmap_write, CTLFLAG_RW,
185 	   &hammer2_ioa_fmap_write, 0, "");
186 SYSCTL_LONG(_vfs_hammer2, OID_AUTO, ioa_volu_write, CTLFLAG_RW,
187 	   &hammer2_ioa_volu_write, 0, "");
188 
189 static int hammer2_vfs_init(struct vfsconf *conf);
190 static int hammer2_vfs_uninit(struct vfsconf *vfsp);
191 static int hammer2_vfs_mount(struct mount *mp, char *path, caddr_t data,
192 				struct ucred *cred);
193 static int hammer2_remount(hammer2_dev_t *, struct mount *, char *,
194 				struct vnode *, struct ucred *);
195 static int hammer2_recovery(hammer2_dev_t *hmp);
196 static int hammer2_vfs_unmount(struct mount *mp, int mntflags);
197 static int hammer2_vfs_root(struct mount *mp, struct vnode **vpp);
198 static int hammer2_vfs_statfs(struct mount *mp, struct statfs *sbp,
199 				struct ucred *cred);
200 static int hammer2_vfs_statvfs(struct mount *mp, struct statvfs *sbp,
201 				struct ucred *cred);
202 static int hammer2_vfs_vget(struct mount *mp, struct vnode *dvp,
203 				ino_t ino, struct vnode **vpp);
204 static int hammer2_vfs_fhtovp(struct mount *mp, struct vnode *rootvp,
205 				struct fid *fhp, struct vnode **vpp);
206 static int hammer2_vfs_vptofh(struct vnode *vp, struct fid *fhp);
207 static int hammer2_vfs_checkexp(struct mount *mp, struct sockaddr *nam,
208 				int *exflagsp, struct ucred **credanonp);
209 
210 static int hammer2_install_volume_header(hammer2_dev_t *hmp);
211 static int hammer2_sync_scan2(struct mount *mp, struct vnode *vp, void *data);
212 
213 static void hammer2_update_pmps(hammer2_dev_t *hmp);
214 
215 static void hammer2_mount_helper(struct mount *mp, hammer2_pfs_t *pmp);
216 static void hammer2_unmount_helper(struct mount *mp, hammer2_pfs_t *pmp,
217 				hammer2_dev_t *hmp);
218 
219 /*
220  * HAMMER2 vfs operations.
221  */
222 static struct vfsops hammer2_vfsops = {
223 	.vfs_init	= hammer2_vfs_init,
224 	.vfs_uninit	= hammer2_vfs_uninit,
225 	.vfs_sync	= hammer2_vfs_sync,
226 	.vfs_mount	= hammer2_vfs_mount,
227 	.vfs_unmount	= hammer2_vfs_unmount,
228 	.vfs_root 	= hammer2_vfs_root,
229 	.vfs_statfs	= hammer2_vfs_statfs,
230 	.vfs_statvfs	= hammer2_vfs_statvfs,
231 	.vfs_vget	= hammer2_vfs_vget,
232 	.vfs_vptofh	= hammer2_vfs_vptofh,
233 	.vfs_fhtovp	= hammer2_vfs_fhtovp,
234 	.vfs_checkexp	= hammer2_vfs_checkexp
235 };
236 
237 MALLOC_DEFINE(M_HAMMER2, "HAMMER2-mount", "");
238 
239 VFS_SET(hammer2_vfsops, hammer2, 0);
240 MODULE_VERSION(hammer2, 1);
241 
242 static
243 int
244 hammer2_vfs_init(struct vfsconf *conf)
245 {
246 	static struct objcache_malloc_args margs_read;
247 	static struct objcache_malloc_args margs_write;
248 	static struct objcache_malloc_args margs_vop;
249 
250 	int error;
251 
252 	error = 0;
253 
254 	if (HAMMER2_BLOCKREF_BYTES != sizeof(struct hammer2_blockref))
255 		error = EINVAL;
256 	if (HAMMER2_INODE_BYTES != sizeof(struct hammer2_inode_data))
257 		error = EINVAL;
258 	if (HAMMER2_VOLUME_BYTES != sizeof(struct hammer2_volume_data))
259 		error = EINVAL;
260 
261 	if (error)
262 		kprintf("HAMMER2 structure size mismatch; cannot continue.\n");
263 
264 	margs_read.objsize = 65536;
265 	margs_read.mtype = M_HAMMER2_DEBUFFER;
266 
267 	margs_write.objsize = 32768;
268 	margs_write.mtype = M_HAMMER2_CBUFFER;
269 
270 	margs_vop.objsize = sizeof(hammer2_xop_t);
271 	margs_vop.mtype = M_HAMMER2;
272 
273 	/*
274 	 * Note thaht for the XOPS cache we want backing store allocations
275 	 * to use M_ZERO.  This is not allowed in objcache_get() (to avoid
276 	 * confusion), so use the backing store function that does it.  This
277 	 * means that initial XOPS objects are zerod but REUSED objects are
278 	 * not.  So we are responsible for cleaning the object up sufficiently
279 	 * for our needs before objcache_put()ing it back (typically just the
280 	 * FIFO indices).
281 	 */
282 	cache_buffer_read = objcache_create(margs_read.mtype->ks_shortdesc,
283 				0, 1, NULL, NULL, NULL,
284 				objcache_malloc_alloc,
285 				objcache_malloc_free,
286 				&margs_read);
287 	cache_buffer_write = objcache_create(margs_write.mtype->ks_shortdesc,
288 				0, 1, NULL, NULL, NULL,
289 				objcache_malloc_alloc,
290 				objcache_malloc_free,
291 				&margs_write);
292 	cache_xops = objcache_create(margs_vop.mtype->ks_shortdesc,
293 				0, 1, NULL, NULL, NULL,
294 				objcache_malloc_alloc_zero,
295 				objcache_malloc_free,
296 				&margs_vop);
297 
298 
299 	lockinit(&hammer2_mntlk, "mntlk", 0, 0);
300 	TAILQ_INIT(&hammer2_mntlist);
301 	TAILQ_INIT(&hammer2_pfslist);
302 
303 	hammer2_limit_dirty_chains = desiredvnodes / 10;
304 
305 	return (error);
306 }
307 
308 static
309 int
310 hammer2_vfs_uninit(struct vfsconf *vfsp __unused)
311 {
312 	objcache_destroy(cache_buffer_read);
313 	objcache_destroy(cache_buffer_write);
314 	objcache_destroy(cache_xops);
315 	return 0;
316 }
317 
318 /*
319  * Core PFS allocator.  Used to allocate the pmp structure for PFS cluster
320  * mounts and the spmp structure for media (hmp) structures.
321  *
322  * pmp->modify_tid tracks new modify_tid transaction ids for front-end
323  * transactions.  Note that synchronization does not use this field.
324  * (typically frontend operations and synchronization cannot run on the
325  * same PFS node at the same time).
326  *
327  * XXX check locking
328  */
329 hammer2_pfs_t *
330 hammer2_pfsalloc(hammer2_chain_t *chain, const hammer2_inode_data_t *ripdata,
331 		 hammer2_tid_t modify_tid, hammer2_dev_t *force_local)
332 {
333 	hammer2_inode_t *iroot;
334 	hammer2_pfs_t *pmp;
335 	int count;
336 	int i;
337 	int j;
338 
339 	/*
340 	 * Locate or create the PFS based on the cluster id.  If ripdata
341 	 * is NULL this is a spmp which is unique and is always allocated.
342 	 *
343 	 * If the device is mounted in local mode all PFSs are considered
344 	 * independent and not part of any cluster (for debugging only).
345 	 */
346 	if (ripdata) {
347 		TAILQ_FOREACH(pmp, &hammer2_pfslist, mntentry) {
348 			if (force_local != pmp->force_local)
349 				continue;
350 			if (force_local == NULL &&
351 			    bcmp(&pmp->pfs_clid, &ripdata->meta.pfs_clid,
352 				 sizeof(pmp->pfs_clid)) == 0) {
353 					break;
354 			} else if (force_local && pmp->pfs_names[0] &&
355 			    strcmp(pmp->pfs_names[0], ripdata->filename) == 0) {
356 					break;
357 			}
358 		}
359 	} else {
360 		pmp = NULL;
361 	}
362 
363 	if (pmp == NULL) {
364 		pmp = kmalloc(sizeof(*pmp), M_HAMMER2, M_WAITOK | M_ZERO);
365 		pmp->force_local = force_local;
366 		hammer2_trans_manage_init(pmp);
367 		kmalloc_create(&pmp->minode, "HAMMER2-inodes");
368 		kmalloc_create(&pmp->mmsg, "HAMMER2-pfsmsg");
369 		lockinit(&pmp->lock, "pfslk", 0, 0);
370 		lockinit(&pmp->lock_nlink, "h2nlink", 0, 0);
371 		spin_init(&pmp->inum_spin, "hm2pfsalloc_inum");
372 		spin_init(&pmp->xop_spin, "h2xop");
373 		RB_INIT(&pmp->inum_tree);
374 		TAILQ_INIT(&pmp->sideq);
375 		spin_init(&pmp->list_spin, "hm2pfsalloc_list");
376 
377 		/*
378 		 * Distribute backend operations to threads
379 		 */
380 		for (j = 0; j < HAMMER2_MAXCLUSTER; ++j)
381 			TAILQ_INIT(&pmp->xopq[j]);
382 		for (j = 0; j < HAMMER2_XOPGROUPS; ++j)
383 			hammer2_xop_group_init(pmp, &pmp->xop_groups[j]);
384 
385 		/*
386 		 * Save the last media transaction id for the flusher.  Set
387 		 * initial
388 		 */
389 		if (ripdata)
390 			pmp->pfs_clid = ripdata->meta.pfs_clid;
391 		TAILQ_INSERT_TAIL(&hammer2_pfslist, pmp, mntentry);
392 
393 		/*
394 		 * The synchronization thread may start too early, make
395 		 * sure it stays frozen until we are ready to let it go.
396 		 * XXX
397 		 */
398 		/*
399 		pmp->primary_thr.flags = HAMMER2_THREAD_FROZEN |
400 					 HAMMER2_THREAD_REMASTER;
401 		*/
402 	}
403 
404 	/*
405 	 * Create the PFS's root inode.
406 	 */
407 	if ((iroot = pmp->iroot) == NULL) {
408 		iroot = hammer2_inode_get(pmp, NULL, NULL, -1);
409 		pmp->iroot = iroot;
410 		hammer2_inode_ref(iroot);
411 		hammer2_inode_unlock(iroot);
412 	}
413 
414 	/*
415 	 * Stop here if no chain is passed in.
416 	 */
417 	if (chain == NULL)
418 		goto done;
419 
420 	/*
421 	 * When a chain is passed in we must add it to the PFS's root
422 	 * inode, update pmp->pfs_types[], and update the syncronization
423 	 * threads.
424 	 *
425 	 * When forcing local mode, mark the PFS as a MASTER regardless.
426 	 *
427 	 * At the moment empty spots can develop due to removals or failures.
428 	 * Ultimately we want to re-fill these spots but doing so might
429 	 * confused running code. XXX
430 	 */
431 	hammer2_inode_ref(iroot);
432 	hammer2_mtx_ex(&iroot->lock);
433 	j = iroot->cluster.nchains;
434 
435 	kprintf("add PFS to pmp %p[%d]\n", pmp, j);
436 
437 	if (j == HAMMER2_MAXCLUSTER) {
438 		kprintf("hammer2_mount: cluster full!\n");
439 		/* XXX fatal error? */
440 	} else {
441 		KKASSERT(chain->pmp == NULL);
442 		chain->pmp = pmp;
443 		hammer2_chain_ref(chain);
444 		iroot->cluster.array[j].chain = chain;
445 		if (force_local)
446 			pmp->pfs_types[j] = HAMMER2_PFSTYPE_MASTER;
447 		else
448 			pmp->pfs_types[j] = ripdata->meta.pfs_type;
449 		pmp->pfs_names[j] = kstrdup(ripdata->filename, M_HAMMER2);
450 		pmp->pfs_hmps[j] = chain->hmp;
451 
452 		/*
453 		 * If the PFS is already mounted we must account
454 		 * for the mount_count here.
455 		 */
456 		if (pmp->mp)
457 			++chain->hmp->mount_count;
458 
459 		/*
460 		 * May have to fixup dirty chain tracking.  Previous
461 		 * pmp was NULL so nothing to undo.
462 		 */
463 		if (chain->flags & HAMMER2_CHAIN_MODIFIED)
464 			hammer2_pfs_memory_inc(pmp);
465 		++j;
466 	}
467 	iroot->cluster.nchains = j;
468 
469 	/*
470 	 * Update nmasters from any PFS inode which is part of the cluster.
471 	 * It is possible that this will result in a value which is too
472 	 * high.  MASTER PFSs are authoritative for pfs_nmasters and will
473 	 * override this value later on.
474 	 *
475 	 * (This informs us of masters that might not currently be
476 	 *  discoverable by this mount).
477 	 */
478 	if (ripdata && pmp->pfs_nmasters < ripdata->meta.pfs_nmasters) {
479 		pmp->pfs_nmasters = ripdata->meta.pfs_nmasters;
480 	}
481 
482 	/*
483 	 * Count visible masters.  Masters are usually added with
484 	 * ripdata->meta.pfs_nmasters set to 1.  This detects when there
485 	 * are more (XXX and must update the master inodes).
486 	 */
487 	count = 0;
488 	for (i = 0; i < iroot->cluster.nchains; ++i) {
489 		if (pmp->pfs_types[i] == HAMMER2_PFSTYPE_MASTER)
490 			++count;
491 	}
492 	if (pmp->pfs_nmasters < count)
493 		pmp->pfs_nmasters = count;
494 
495 	/*
496 	 * Create missing synchronization and support threads.
497 	 *
498 	 * Single-node masters (including snapshots) have nothing to
499 	 * synchronize and do not require this thread.
500 	 *
501 	 * Multi-node masters or any number of soft masters, slaves, copy,
502 	 * or other PFS types need the thread.
503 	 *
504 	 * Each thread is responsible for its particular cluster index.
505 	 * We use independent threads so stalls or mismatches related to
506 	 * any given target do not affect other targets.
507 	 */
508 	for (i = 0; i < iroot->cluster.nchains; ++i) {
509 		/*
510 		 * Single-node masters (including snapshots) have nothing
511 		 * to synchronize and will make direct xops support calls,
512 		 * thus they do not require this thread.
513 		 *
514 		 * Note that there can be thousands of snapshots.  We do not
515 		 * want to create thousands of threads.
516 		 */
517 		if (pmp->pfs_nmasters <= 1 &&
518 		    pmp->pfs_types[i] == HAMMER2_PFSTYPE_MASTER) {
519 			continue;
520 		}
521 
522 		/*
523 		 * Sync support thread
524 		 */
525 		if (pmp->sync_thrs[i].td == NULL) {
526 			hammer2_thr_create(&pmp->sync_thrs[i], pmp,
527 					   "h2nod", i, -1,
528 					   hammer2_primary_sync_thread);
529 		}
530 	}
531 
532 	/*
533 	 * Create missing Xop threads
534 	 */
535 	if (pmp->mp)
536 		hammer2_xop_helper_create(pmp);
537 
538 	hammer2_mtx_unlock(&iroot->lock);
539 	hammer2_inode_drop(iroot);
540 done:
541 	return pmp;
542 }
543 
544 /*
545  * Destroy a PFS, typically only occurs after the last mount on a device
546  * has gone away.
547  */
548 static void
549 hammer2_pfsfree(hammer2_pfs_t *pmp)
550 {
551 	hammer2_inode_t *iroot;
552 	int i;
553 	int j;
554 
555 	/*
556 	 * Cleanup our reference on iroot.  iroot is (should) not be needed
557 	 * by the flush code.
558 	 */
559 	TAILQ_REMOVE(&hammer2_pfslist, pmp, mntentry);
560 
561 	iroot = pmp->iroot;
562 	if (iroot) {
563 		for (i = 0; i < iroot->cluster.nchains; ++i) {
564 			hammer2_thr_delete(&pmp->sync_thrs[i]);
565 			for (j = 0; j < HAMMER2_XOPGROUPS; ++j)
566 				hammer2_thr_delete(&pmp->xop_groups[j].thrs[i]);
567 		}
568 #if REPORT_REFS_ERRORS
569 		if (pmp->iroot->refs != 1)
570 			kprintf("PMP->IROOT %p REFS WRONG %d\n",
571 				pmp->iroot, pmp->iroot->refs);
572 #else
573 		KKASSERT(pmp->iroot->refs == 1);
574 #endif
575 		/* ref for pmp->iroot */
576 		hammer2_inode_drop(pmp->iroot);
577 		pmp->iroot = NULL;
578 	}
579 
580 	kmalloc_destroy(&pmp->mmsg);
581 	kmalloc_destroy(&pmp->minode);
582 
583 	kfree(pmp, M_HAMMER2);
584 }
585 
586 /*
587  * Remove all references to hmp from the pfs list.  Any PFS which becomes
588  * empty is terminated and freed.
589  *
590  * XXX inefficient.
591  */
592 static void
593 hammer2_pfsfree_scan(hammer2_dev_t *hmp)
594 {
595 	hammer2_pfs_t *pmp;
596 	hammer2_inode_t *iroot;
597 	hammer2_chain_t *rchain;
598 	int didfreeze;
599 	int i;
600 	int j;
601 
602 again:
603 	TAILQ_FOREACH(pmp, &hammer2_pfslist, mntentry) {
604 		if ((iroot = pmp->iroot) == NULL)
605 			continue;
606 		if (hmp->spmp == pmp) {
607 			kprintf("unmount hmp %p remove spmp %p\n",
608 				hmp, pmp);
609 			hmp->spmp = NULL;
610 		}
611 
612 		/*
613 		 * Determine if this PFS is affected.  If it is we must
614 		 * freeze all management threads and lock its iroot.
615 		 *
616 		 * Freezing a management thread forces it idle, operations
617 		 * in-progress will be aborted and it will have to start
618 		 * over again when unfrozen, or exit if told to exit.
619 		 */
620 		for (i = 0; i < HAMMER2_MAXCLUSTER; ++i) {
621 			if (pmp->pfs_hmps[i] == hmp)
622 				break;
623 		}
624 		if (i != HAMMER2_MAXCLUSTER) {
625 			/*
626 			 * Make sure all synchronization threads are locked
627 			 * down.
628 			 */
629 			for (i = 0; i < HAMMER2_MAXCLUSTER; ++i) {
630 				if (pmp->pfs_hmps[i] == NULL)
631 					continue;
632 				hammer2_thr_freeze_async(&pmp->sync_thrs[i]);
633 				for (j = 0; j < HAMMER2_XOPGROUPS; ++j) {
634 					hammer2_thr_freeze_async(
635 						&pmp->xop_groups[j].thrs[i]);
636 				}
637 			}
638 			for (i = 0; i < HAMMER2_MAXCLUSTER; ++i) {
639 				if (pmp->pfs_hmps[i] == NULL)
640 					continue;
641 				hammer2_thr_freeze(&pmp->sync_thrs[i]);
642 				for (j = 0; j < HAMMER2_XOPGROUPS; ++j) {
643 					hammer2_thr_freeze(
644 						&pmp->xop_groups[j].thrs[i]);
645 				}
646 			}
647 
648 			/*
649 			 * Lock the inode and clean out matching chains.
650 			 * Note that we cannot use hammer2_inode_lock_*()
651 			 * here because that would attempt to validate the
652 			 * cluster that we are in the middle of ripping
653 			 * apart.
654 			 *
655 			 * WARNING! We are working directly on the inodes
656 			 *	    embedded cluster.
657 			 */
658 			hammer2_mtx_ex(&iroot->lock);
659 
660 			/*
661 			 * Remove the chain from matching elements of the PFS.
662 			 */
663 			for (i = 0; i < HAMMER2_MAXCLUSTER; ++i) {
664 				if (pmp->pfs_hmps[i] != hmp)
665 					continue;
666 				hammer2_thr_delete(&pmp->sync_thrs[i]);
667 				for (j = 0; j < HAMMER2_XOPGROUPS; ++j) {
668 					hammer2_thr_delete(
669 						&pmp->xop_groups[j].thrs[i]);
670 				}
671 				rchain = iroot->cluster.array[i].chain;
672 				iroot->cluster.array[i].chain = NULL;
673 				pmp->pfs_types[i] = 0;
674 				if (pmp->pfs_names[i]) {
675 					kfree(pmp->pfs_names[i], M_HAMMER2);
676 					pmp->pfs_names[i] = NULL;
677 				}
678 				if (rchain) {
679 					hammer2_chain_drop(rchain);
680 					/* focus hint */
681 					if (iroot->cluster.focus == rchain)
682 						iroot->cluster.focus = NULL;
683 				}
684 				pmp->pfs_hmps[i] = NULL;
685 			}
686 			hammer2_mtx_unlock(&iroot->lock);
687 			didfreeze = 1;	/* remaster, unfreeze down below */
688 		} else {
689 			didfreeze = 0;
690 		}
691 
692 		/*
693 		 * Cleanup trailing chains.  Gaps may remain.
694 		 */
695 		for (i = HAMMER2_MAXCLUSTER - 1; i >= 0; --i) {
696 			if (pmp->pfs_hmps[i])
697 				break;
698 		}
699 		iroot->cluster.nchains = i + 1;
700 
701 		/*
702 		 * If the PMP has no elements remaining we can destroy it.
703 		 * (this will transition management threads from frozen->exit).
704 		 */
705 		if (iroot->cluster.nchains == 0) {
706 			kprintf("unmount hmp %p last ref to PMP=%p\n",
707 				hmp, pmp);
708 			hammer2_pfsfree(pmp);
709 			goto again;
710 		}
711 
712 		/*
713 		 * If elements still remain we need to set the REMASTER
714 		 * flag and unfreeze it.
715 		 */
716 		if (didfreeze) {
717 			for (i = 0; i < HAMMER2_MAXCLUSTER; ++i) {
718 				if (pmp->pfs_hmps[i] == NULL)
719 					continue;
720 				hammer2_thr_remaster(&pmp->sync_thrs[i]);
721 				hammer2_thr_unfreeze(&pmp->sync_thrs[i]);
722 				for (j = 0; j < HAMMER2_XOPGROUPS; ++j) {
723 					hammer2_thr_remaster(
724 						&pmp->xop_groups[j].thrs[i]);
725 					hammer2_thr_unfreeze(
726 						&pmp->xop_groups[j].thrs[i]);
727 				}
728 			}
729 		}
730 	}
731 }
732 
733 /*
734  * Mount or remount HAMMER2 fileystem from physical media
735  *
736  *	mountroot
737  *		mp		mount point structure
738  *		path		NULL
739  *		data		<unused>
740  *		cred		<unused>
741  *
742  *	mount
743  *		mp		mount point structure
744  *		path		path to mount point
745  *		data		pointer to argument structure in user space
746  *			volume	volume path (device@LABEL form)
747  *			hflags	user mount flags
748  *		cred		user credentials
749  *
750  * RETURNS:	0	Success
751  *		!0	error number
752  */
753 static
754 int
755 hammer2_vfs_mount(struct mount *mp, char *path, caddr_t data,
756 		  struct ucred *cred)
757 {
758 	struct hammer2_mount_info info;
759 	hammer2_pfs_t *pmp;
760 	hammer2_pfs_t *spmp;
761 	hammer2_dev_t *hmp;
762 	hammer2_dev_t *force_local;
763 	hammer2_key_t key_next;
764 	hammer2_key_t key_dummy;
765 	hammer2_key_t lhc;
766 	struct vnode *devvp;
767 	struct nlookupdata nd;
768 	hammer2_chain_t *parent;
769 	hammer2_chain_t *chain;
770 	hammer2_cluster_t *cluster;
771 	const hammer2_inode_data_t *ripdata;
772 	hammer2_blockref_t bref;
773 	struct file *fp;
774 	char devstr[MNAMELEN];
775 	size_t size;
776 	size_t done;
777 	char *dev;
778 	char *label;
779 	int ronly = 1;
780 	int error;
781 	int cache_index;
782 	int i;
783 
784 	hmp = NULL;
785 	pmp = NULL;
786 	dev = NULL;
787 	label = NULL;
788 	devvp = NULL;
789 	cache_index = -1;
790 
791 	kprintf("hammer2_mount\n");
792 
793 	if (path == NULL) {
794 		/*
795 		 * Root mount
796 		 */
797 		bzero(&info, sizeof(info));
798 		info.cluster_fd = -1;
799 		ksnprintf(devstr, sizeof(devstr), "%s",
800 			  mp->mnt_stat.f_mntfromname);
801 		kprintf("hammer2_mount: root '%s'\n", devstr);
802 	} else {
803 		/*
804 		 * Non-root mount or updating a mount
805 		 */
806 		error = copyin(data, &info, sizeof(info));
807 		if (error)
808 			return (error);
809 
810 		error = copyinstr(info.volume, devstr, MNAMELEN - 1, &done);
811 		if (error)
812 			return (error);
813 	}
814 
815 	/* Extract device and label */
816 	dev = devstr;
817 	label = strchr(devstr, '@');
818 	if (label == NULL ||
819 	    ((label + 1) - dev) > done) {
820 		return (EINVAL);
821 	}
822 	*label = '\0';
823 	label++;
824 	if (*label == '\0')
825 		return (EINVAL);
826 
827 	if (mp->mnt_flag & MNT_UPDATE) {
828 		/*
829 		 * Update mount.  Note that pmp->iroot->cluster is
830 		 * an inode-embedded cluster and thus cannot be
831 		 * directly locked.
832 		 *
833 		 * XXX HAMMER2 needs to implement NFS export via
834 		 *     mountctl.
835 		 */
836 		pmp = MPTOPMP(mp);
837 		pmp->hflags = info.hflags;
838 		cluster = &pmp->iroot->cluster;
839 		for (i = 0; i < cluster->nchains; ++i) {
840 			if (cluster->array[i].chain == NULL)
841 				continue;
842 			hmp = cluster->array[i].chain->hmp;
843 			devvp = hmp->devvp;
844 			error = hammer2_remount(hmp, mp, path,
845 						devvp, cred);
846 			if (error)
847 				break;
848 		}
849 
850 		return error;
851 	}
852 
853 	/*
854 	 * HMP device mount
855 	 *
856 	 * Lookup name and verify it refers to a block device.
857 	 */
858 	if (path) {
859 		error = nlookup_init(&nd, dev, UIO_SYSSPACE, NLC_FOLLOW);
860 		if (error == 0)
861 			error = nlookup(&nd);
862 		if (error == 0)
863 			error = cache_vref(&nd.nl_nch, nd.nl_cred, &devvp);
864 		nlookup_done(&nd);
865 	} else {
866 		/* root mount */
867 		cdev_t cdev = kgetdiskbyname(dev);
868 		error = bdevvp(cdev, &devvp);
869 		if (error)
870 			kprintf("hammer2: cannot find '%s'\n", dev);
871 	}
872 
873 	if (error == 0) {
874 		if (vn_isdisk(devvp, &error))
875 			error = vfs_mountedon(devvp);
876 	}
877 
878 	/*
879 	 * Determine if the device has already been mounted.  After this
880 	 * check hmp will be non-NULL if we are doing the second or more
881 	 * hammer2 mounts from the same device.
882 	 */
883 	lockmgr(&hammer2_mntlk, LK_EXCLUSIVE);
884 	TAILQ_FOREACH(hmp, &hammer2_mntlist, mntentry) {
885 		if (hmp->devvp == devvp)
886 			break;
887 	}
888 
889 	/*
890 	 * Open the device if this isn't a secondary mount and construct
891 	 * the H2 device mount (hmp).
892 	 */
893 	if (hmp == NULL) {
894 		hammer2_chain_t *schain;
895 		hammer2_xid_t xid;
896 
897 		if (error == 0 && vcount(devvp) > 0)
898 			error = EBUSY;
899 
900 		/*
901 		 * Now open the device
902 		 */
903 		if (error == 0) {
904 			ronly = ((mp->mnt_flag & MNT_RDONLY) != 0);
905 			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
906 			error = vinvalbuf(devvp, V_SAVE, 0, 0);
907 			if (error == 0) {
908 				error = VOP_OPEN(devvp,
909 						 ronly ? FREAD : FREAD | FWRITE,
910 						 FSCRED, NULL);
911 			}
912 			vn_unlock(devvp);
913 		}
914 		if (error && devvp) {
915 			vrele(devvp);
916 			devvp = NULL;
917 		}
918 		if (error) {
919 			lockmgr(&hammer2_mntlk, LK_RELEASE);
920 			return error;
921 		}
922 		hmp = kmalloc(sizeof(*hmp), M_HAMMER2, M_WAITOK | M_ZERO);
923 		ksnprintf(hmp->devrepname, sizeof(hmp->devrepname), "%s", dev);
924 		hmp->ronly = ronly;
925 		hmp->devvp = devvp;
926 		hmp->hflags = info.hflags & HMNT2_DEVFLAGS;
927 		kmalloc_create(&hmp->mchain, "HAMMER2-chains");
928 		TAILQ_INSERT_TAIL(&hammer2_mntlist, hmp, mntentry);
929 		RB_INIT(&hmp->iotree);
930 		spin_init(&hmp->io_spin, "hm2mount_io");
931 		spin_init(&hmp->list_spin, "hm2mount_list");
932 		TAILQ_INIT(&hmp->flushq);
933 
934 		lockinit(&hmp->vollk, "h2vol", 0, 0);
935 		lockinit(&hmp->bulklk, "h2bulk", 0, 0);
936 
937 		/*
938 		 * vchain setup. vchain.data is embedded.
939 		 * vchain.refs is initialized and will never drop to 0.
940 		 *
941 		 * NOTE! voldata is not yet loaded.
942 		 */
943 		hmp->vchain.hmp = hmp;
944 		hmp->vchain.refs = 1;
945 		hmp->vchain.data = (void *)&hmp->voldata;
946 		hmp->vchain.bref.type = HAMMER2_BREF_TYPE_VOLUME;
947 		hmp->vchain.bref.data_off = 0 | HAMMER2_PBUFRADIX;
948 		hmp->vchain.bref.mirror_tid = hmp->voldata.mirror_tid;
949 
950 		hammer2_chain_core_init(&hmp->vchain);
951 		/* hmp->vchain.u.xxx is left NULL */
952 
953 		/*
954 		 * fchain setup.  fchain.data is embedded.
955 		 * fchain.refs is initialized and will never drop to 0.
956 		 *
957 		 * The data is not used but needs to be initialized to
958 		 * pass assertion muster.  We use this chain primarily
959 		 * as a placeholder for the freemap's top-level RBTREE
960 		 * so it does not interfere with the volume's topology
961 		 * RBTREE.
962 		 */
963 		hmp->fchain.hmp = hmp;
964 		hmp->fchain.refs = 1;
965 		hmp->fchain.data = (void *)&hmp->voldata.freemap_blockset;
966 		hmp->fchain.bref.type = HAMMER2_BREF_TYPE_FREEMAP;
967 		hmp->fchain.bref.data_off = 0 | HAMMER2_PBUFRADIX;
968 		hmp->fchain.bref.mirror_tid = hmp->voldata.freemap_tid;
969 		hmp->fchain.bref.methods =
970 			HAMMER2_ENC_CHECK(HAMMER2_CHECK_FREEMAP) |
971 			HAMMER2_ENC_COMP(HAMMER2_COMP_NONE);
972 
973 		hammer2_chain_core_init(&hmp->fchain);
974 		/* hmp->fchain.u.xxx is left NULL */
975 
976 		/*
977 		 * Install the volume header and initialize fields from
978 		 * voldata.
979 		 */
980 		error = hammer2_install_volume_header(hmp);
981 		if (error) {
982 			hammer2_unmount_helper(mp, NULL, hmp);
983 			lockmgr(&hammer2_mntlk, LK_RELEASE);
984 			hammer2_vfs_unmount(mp, MNT_FORCE);
985 			return error;
986 		}
987 
988 		/*
989 		 * Really important to get these right or flush will get
990 		 * confused.
991 		 */
992 		hmp->spmp = hammer2_pfsalloc(NULL, NULL, 0, NULL);
993 		kprintf("alloc spmp %p tid %016jx\n",
994 			hmp->spmp, hmp->voldata.mirror_tid);
995 		spmp = hmp->spmp;
996 
997 		/*
998 		 * Dummy-up vchain and fchain's modify_tid.  mirror_tid
999 		 * is inherited from the volume header.
1000 		 */
1001 		xid = 0;
1002 		hmp->vchain.bref.mirror_tid = hmp->voldata.mirror_tid;
1003 		hmp->vchain.bref.modify_tid = hmp->vchain.bref.mirror_tid;
1004 		hmp->vchain.pmp = spmp;
1005 		hmp->fchain.bref.mirror_tid = hmp->voldata.freemap_tid;
1006 		hmp->fchain.bref.modify_tid = hmp->fchain.bref.mirror_tid;
1007 		hmp->fchain.pmp = spmp;
1008 
1009 		/*
1010 		 * First locate the super-root inode, which is key 0
1011 		 * relative to the volume header's blockset.
1012 		 *
1013 		 * Then locate the root inode by scanning the directory keyspace
1014 		 * represented by the label.
1015 		 */
1016 		parent = hammer2_chain_lookup_init(&hmp->vchain, 0);
1017 		schain = hammer2_chain_lookup(&parent, &key_dummy,
1018 				      HAMMER2_SROOT_KEY, HAMMER2_SROOT_KEY,
1019 				      &cache_index, 0);
1020 		hammer2_chain_lookup_done(parent);
1021 		if (schain == NULL) {
1022 			kprintf("hammer2_mount: invalid super-root\n");
1023 			hammer2_unmount_helper(mp, NULL, hmp);
1024 			lockmgr(&hammer2_mntlk, LK_RELEASE);
1025 			hammer2_vfs_unmount(mp, MNT_FORCE);
1026 			return EINVAL;
1027 		}
1028 		if (schain->error) {
1029 			kprintf("hammer2_mount: error %s reading super-root\n",
1030 				hammer2_error_str(schain->error));
1031 			hammer2_chain_unlock(schain);
1032 			hammer2_chain_drop(schain);
1033 			schain = NULL;
1034 			hammer2_unmount_helper(mp, NULL, hmp);
1035 			lockmgr(&hammer2_mntlk, LK_RELEASE);
1036 			hammer2_vfs_unmount(mp, MNT_FORCE);
1037 			return EINVAL;
1038 		}
1039 
1040 		/*
1041 		 * The super-root always uses an inode_tid of 1 when
1042 		 * creating PFSs.
1043 		 */
1044 		spmp->inode_tid = 1;
1045 		spmp->modify_tid = schain->bref.modify_tid + 1;
1046 
1047 		/*
1048 		 * Sanity-check schain's pmp and finish initialization.
1049 		 * Any chain belonging to the super-root topology should
1050 		 * have a NULL pmp (not even set to spmp).
1051 		 */
1052 		ripdata = &hammer2_chain_rdata(schain)->ipdata;
1053 		KKASSERT(schain->pmp == NULL);
1054 		spmp->pfs_clid = ripdata->meta.pfs_clid;
1055 
1056 		/*
1057 		 * Replace the dummy spmp->iroot with a real one.  It's
1058 		 * easier to just do a wholesale replacement than to try
1059 		 * to update the chain and fixup the iroot fields.
1060 		 *
1061 		 * The returned inode is locked with the supplied cluster.
1062 		 */
1063 		cluster = hammer2_cluster_from_chain(schain);
1064 		hammer2_inode_drop(spmp->iroot);
1065 		spmp->iroot = NULL;
1066 		spmp->iroot = hammer2_inode_get(spmp, NULL, cluster, -1);
1067 		spmp->spmp_hmp = hmp;
1068 		spmp->pfs_types[0] = ripdata->meta.pfs_type;
1069 		spmp->pfs_hmps[0] = hmp;
1070 		hammer2_inode_ref(spmp->iroot);
1071 		hammer2_inode_unlock(spmp->iroot);
1072 		hammer2_cluster_unlock(cluster);
1073 		hammer2_cluster_drop(cluster);
1074 		schain = NULL;
1075 		/* leave spmp->iroot with one ref */
1076 
1077 		if ((mp->mnt_flag & MNT_RDONLY) == 0) {
1078 			error = hammer2_recovery(hmp);
1079 			/* XXX do something with error */
1080 		}
1081 		hammer2_update_pmps(hmp);
1082 		hammer2_iocom_init(hmp);
1083 
1084 		/*
1085 		 * Ref the cluster management messaging descriptor.  The mount
1086 		 * program deals with the other end of the communications pipe.
1087 		 *
1088 		 * Root mounts typically do not supply one.
1089 		 */
1090 		if (info.cluster_fd >= 0) {
1091 			fp = holdfp(curproc->p_fd, info.cluster_fd, -1);
1092 			if (fp) {
1093 				hammer2_cluster_reconnect(hmp, fp);
1094 			} else {
1095 				kprintf("hammer2_mount: bad cluster_fd!\n");
1096 			}
1097 		}
1098 	} else {
1099 		spmp = hmp->spmp;
1100 		if (info.hflags & HMNT2_DEVFLAGS) {
1101 			kprintf("hammer2: Warning: mount flags pertaining "
1102 				"to the whole device may only be specified "
1103 				"on the first mount of the device: %08x\n",
1104 				info.hflags & HMNT2_DEVFLAGS);
1105 		}
1106 	}
1107 
1108 	/*
1109 	 * Force local mount (disassociate all PFSs from their clusters).
1110 	 * Used primarily for debugging.
1111 	 */
1112 	force_local = (hmp->hflags & HMNT2_LOCAL) ? hmp : NULL;
1113 
1114 	/*
1115 	 * Lookup the mount point under the media-localized super-root.
1116 	 * Scanning hammer2_pfslist doesn't help us because it represents
1117 	 * PFS cluster ids which can aggregate several named PFSs together.
1118 	 *
1119 	 * cluster->pmp will incorrectly point to spmp and must be fixed
1120 	 * up later on.
1121 	 */
1122 	hammer2_inode_lock(spmp->iroot, 0);
1123 	parent = hammer2_inode_chain(spmp->iroot, 0, HAMMER2_RESOLVE_ALWAYS);
1124 	lhc = hammer2_dirhash(label, strlen(label));
1125 	chain = hammer2_chain_lookup(&parent, &key_next,
1126 				     lhc, lhc + HAMMER2_DIRHASH_LOMASK,
1127 				     &cache_index, 0);
1128 	while (chain) {
1129 		if (chain->bref.type == HAMMER2_BREF_TYPE_INODE &&
1130 		    strcmp(label, chain->data->ipdata.filename) == 0) {
1131 			break;
1132 		}
1133 		chain = hammer2_chain_next(&parent, chain, &key_next,
1134 					    key_next,
1135 					    lhc + HAMMER2_DIRHASH_LOMASK,
1136 					    &cache_index, 0);
1137 	}
1138 	if (parent) {
1139 		hammer2_chain_unlock(parent);
1140 		hammer2_chain_drop(parent);
1141 	}
1142 	hammer2_inode_unlock(spmp->iroot);
1143 
1144 	/*
1145 	 * PFS could not be found?
1146 	 */
1147 	if (chain == NULL) {
1148 		kprintf("hammer2_mount: PFS label not found\n");
1149 		hammer2_unmount_helper(mp, NULL, hmp);
1150 		lockmgr(&hammer2_mntlk, LK_RELEASE);
1151 		hammer2_vfs_unmount(mp, MNT_FORCE);
1152 
1153 		return EINVAL;
1154 	}
1155 
1156 	/*
1157 	 * Acquire the pmp structure (it should have already been allocated
1158 	 * via hammer2_update_pmps() so do not pass cluster in to add to
1159 	 * available chains).
1160 	 *
1161 	 * Check if the cluster has already been mounted.  A cluster can
1162 	 * only be mounted once, use null mounts to mount additional copies.
1163 	 */
1164 	ripdata = &chain->data->ipdata;
1165 	bref = chain->bref;
1166 	pmp = hammer2_pfsalloc(NULL, ripdata, bref.modify_tid, force_local);
1167 	hammer2_chain_unlock(chain);
1168 	hammer2_chain_drop(chain);
1169 
1170 	if (pmp->mp) {
1171 		kprintf("hammer2_mount: PFS already mounted!\n");
1172 		hammer2_unmount_helper(mp, NULL, hmp);
1173 		lockmgr(&hammer2_mntlk, LK_RELEASE);
1174 		hammer2_vfs_unmount(mp, MNT_FORCE);
1175 
1176 		return EBUSY;
1177 	}
1178 
1179 	/*
1180 	 * Finish the mount
1181 	 */
1182         kprintf("hammer2_mount hmp=%p pmp=%p\n", hmp, pmp);
1183 
1184 	pmp->hflags = info.hflags;
1185         mp->mnt_flag = MNT_LOCAL;
1186         mp->mnt_kern_flag |= MNTK_ALL_MPSAFE;   /* all entry pts are SMP */
1187         mp->mnt_kern_flag |= MNTK_THR_SYNC;     /* new vsyncscan semantics */
1188 
1189         /*
1190          * required mount structure initializations
1191          */
1192         mp->mnt_stat.f_iosize = HAMMER2_PBUFSIZE;
1193         mp->mnt_stat.f_bsize = HAMMER2_PBUFSIZE;
1194 
1195         mp->mnt_vstat.f_frsize = HAMMER2_PBUFSIZE;
1196         mp->mnt_vstat.f_bsize = HAMMER2_PBUFSIZE;
1197 
1198         /*
1199          * Optional fields
1200          */
1201         mp->mnt_iosize_max = MAXPHYS;
1202 
1203 	/*
1204 	 * Connect up mount pointers.
1205 	 */
1206 	hammer2_mount_helper(mp, pmp);
1207 
1208         lockmgr(&hammer2_mntlk, LK_RELEASE);
1209 
1210 	/*
1211 	 * Finish setup
1212 	 */
1213 	vfs_getnewfsid(mp);
1214 	vfs_add_vnodeops(mp, &hammer2_vnode_vops, &mp->mnt_vn_norm_ops);
1215 	vfs_add_vnodeops(mp, &hammer2_spec_vops, &mp->mnt_vn_spec_ops);
1216 	vfs_add_vnodeops(mp, &hammer2_fifo_vops, &mp->mnt_vn_fifo_ops);
1217 
1218 	if (path) {
1219 		copyinstr(info.volume, mp->mnt_stat.f_mntfromname,
1220 			  MNAMELEN - 1, &size);
1221 		bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
1222 	} /* else root mount, already in there */
1223 
1224 	bzero(mp->mnt_stat.f_mntonname, sizeof(mp->mnt_stat.f_mntonname));
1225 	if (path) {
1226 		copyinstr(path, mp->mnt_stat.f_mntonname,
1227 			  sizeof(mp->mnt_stat.f_mntonname) - 1,
1228 			  &size);
1229 	} else {
1230 		/* root mount */
1231 		mp->mnt_stat.f_mntonname[0] = '/';
1232 	}
1233 
1234 	/*
1235 	 * Initial statfs to prime mnt_stat.
1236 	 */
1237 	hammer2_vfs_statfs(mp, &mp->mnt_stat, cred);
1238 
1239 	return 0;
1240 }
1241 
1242 /*
1243  * Scan PFSs under the super-root and create hammer2_pfs structures.
1244  */
1245 static
1246 void
1247 hammer2_update_pmps(hammer2_dev_t *hmp)
1248 {
1249 	const hammer2_inode_data_t *ripdata;
1250 	hammer2_chain_t *parent;
1251 	hammer2_chain_t *chain;
1252 	hammer2_blockref_t bref;
1253 	hammer2_dev_t *force_local;
1254 	hammer2_pfs_t *spmp;
1255 	hammer2_pfs_t *pmp;
1256 	hammer2_key_t key_next;
1257 	int cache_index = -1;
1258 
1259 	/*
1260 	 * Force local mount (disassociate all PFSs from their clusters).
1261 	 * Used primarily for debugging.
1262 	 */
1263 	force_local = (hmp->hflags & HMNT2_LOCAL) ? hmp : NULL;
1264 
1265 	/*
1266 	 * Lookup mount point under the media-localized super-root.
1267 	 *
1268 	 * cluster->pmp will incorrectly point to spmp and must be fixed
1269 	 * up later on.
1270 	 */
1271 	spmp = hmp->spmp;
1272 	hammer2_inode_lock(spmp->iroot, 0);
1273 	parent = hammer2_inode_chain(spmp->iroot, 0, HAMMER2_RESOLVE_ALWAYS);
1274 	chain = hammer2_chain_lookup(&parent, &key_next,
1275 					 HAMMER2_KEY_MIN, HAMMER2_KEY_MAX,
1276 					 &cache_index, 0);
1277 	while (chain) {
1278 		if (chain->bref.type != HAMMER2_BREF_TYPE_INODE)
1279 			continue;
1280 		ripdata = &chain->data->ipdata;
1281 		bref = chain->bref;
1282 		kprintf("ADD LOCAL PFS: %s\n", ripdata->filename);
1283 
1284 		pmp = hammer2_pfsalloc(chain, ripdata,
1285 				       bref.modify_tid, force_local);
1286 		chain = hammer2_chain_next(&parent, chain, &key_next,
1287 					   key_next, HAMMER2_KEY_MAX,
1288 					   &cache_index, 0);
1289 	}
1290 	if (parent) {
1291 		hammer2_chain_unlock(parent);
1292 		hammer2_chain_drop(parent);
1293 	}
1294 	hammer2_inode_unlock(spmp->iroot);
1295 }
1296 
1297 static
1298 int
1299 hammer2_remount(hammer2_dev_t *hmp, struct mount *mp, char *path __unused,
1300 		struct vnode *devvp, struct ucred *cred)
1301 {
1302 	int error;
1303 
1304 	if (hmp->ronly && (mp->mnt_kern_flag & MNTK_WANTRDWR)) {
1305 		error = hammer2_recovery(hmp);
1306 	} else {
1307 		error = 0;
1308 	}
1309 	return error;
1310 }
1311 
1312 static
1313 int
1314 hammer2_vfs_unmount(struct mount *mp, int mntflags)
1315 {
1316 	hammer2_pfs_t *pmp;
1317 	int flags;
1318 	int error = 0;
1319 
1320 	pmp = MPTOPMP(mp);
1321 
1322 	if (pmp == NULL)
1323 		return(0);
1324 
1325 	lockmgr(&hammer2_mntlk, LK_EXCLUSIVE);
1326 
1327 	/*
1328 	 * If mount initialization proceeded far enough we must flush
1329 	 * its vnodes and sync the underlying mount points.  Three syncs
1330 	 * are required to fully flush the filesystem (freemap updates lag
1331 	 * by one flush, and one extra for safety).
1332 	 */
1333 	if (mntflags & MNT_FORCE)
1334 		flags = FORCECLOSE;
1335 	else
1336 		flags = 0;
1337 	if (pmp->iroot) {
1338 		error = vflush(mp, 0, flags);
1339 		if (error)
1340 			goto failed;
1341 		hammer2_vfs_sync(mp, MNT_WAIT);
1342 		hammer2_vfs_sync(mp, MNT_WAIT);
1343 		hammer2_vfs_sync(mp, MNT_WAIT);
1344 	}
1345 
1346 	/*
1347 	 * Cleanup the frontend support XOPS threads
1348 	 */
1349 	hammer2_xop_helper_cleanup(pmp);
1350 
1351 	/*
1352 	 * Cleanup our reference on ihidden.
1353 	 */
1354 	if (pmp->ihidden) {
1355 		hammer2_inode_drop(pmp->ihidden);
1356 		pmp->ihidden = NULL;
1357 	}
1358 	if (pmp->mp)
1359 		hammer2_unmount_helper(mp, pmp, NULL);
1360 
1361 	error = 0;
1362 failed:
1363 	lockmgr(&hammer2_mntlk, LK_RELEASE);
1364 
1365 	return (error);
1366 }
1367 
1368 /*
1369  * Mount helper, hook the system mount into our PFS.
1370  * The mount lock is held.
1371  *
1372  * We must bump the mount_count on related devices for any
1373  * mounted PFSs.
1374  */
1375 static
1376 void
1377 hammer2_mount_helper(struct mount *mp, hammer2_pfs_t *pmp)
1378 {
1379 	hammer2_cluster_t *cluster;
1380 	hammer2_chain_t *rchain;
1381 	int i;
1382 
1383         mp->mnt_data = (qaddr_t)pmp;
1384 	pmp->mp = mp;
1385 
1386 	/*
1387 	 * After pmp->mp is set we have to adjust hmp->mount_count.
1388 	 */
1389 	cluster = &pmp->iroot->cluster;
1390 	for (i = 0; i < cluster->nchains; ++i) {
1391 		rchain = cluster->array[i].chain;
1392 		if (rchain == NULL)
1393 			continue;
1394 		++rchain->hmp->mount_count;
1395 		kprintf("hammer2_mount hmp=%p ++mount_count=%d\n",
1396 			rchain->hmp, rchain->hmp->mount_count);
1397 	}
1398 
1399 	/*
1400 	 * Create missing Xop threads
1401 	 */
1402 	hammer2_xop_helper_create(pmp);
1403 }
1404 
1405 /*
1406  * Mount helper, unhook the system mount from our PFS.
1407  * The mount lock is held.
1408  *
1409  * If hmp is supplied a mount responsible for being the first to open
1410  * the block device failed and the block device and all PFSs using the
1411  * block device must be cleaned up.
1412  *
1413  * If pmp is supplied multiple devices might be backing the PFS and each
1414  * must be disconnect.  This might not be the last PFS using some of the
1415  * underlying devices.  Also, we have to adjust our hmp->mount_count
1416  * accounting for the devices backing the pmp which is now undergoing an
1417  * unmount.
1418  */
1419 static
1420 void
1421 hammer2_unmount_helper(struct mount *mp, hammer2_pfs_t *pmp, hammer2_dev_t *hmp)
1422 {
1423 	hammer2_cluster_t *cluster;
1424 	hammer2_chain_t *rchain;
1425 	struct vnode *devvp;
1426 	int dumpcnt;
1427 	int ronly = 0;
1428 	int i;
1429 
1430 	/*
1431 	 * If no device supplied this is a high-level unmount and we have to
1432 	 * to disconnect the mount, adjust mount_count, and locate devices
1433 	 * that might now have no mounts.
1434 	 */
1435 	if (pmp) {
1436 		KKASSERT(hmp == NULL);
1437 		KKASSERT((void *)(intptr_t)mp->mnt_data == pmp);
1438 		pmp->mp = NULL;
1439 		mp->mnt_data = NULL;
1440 
1441 		/*
1442 		 * After pmp->mp is cleared we have to account for
1443 		 * mount_count.
1444 		 */
1445 		cluster = &pmp->iroot->cluster;
1446 		for (i = 0; i < cluster->nchains; ++i) {
1447 			rchain = cluster->array[i].chain;
1448 			if (rchain == NULL)
1449 				continue;
1450 			--rchain->hmp->mount_count;
1451 			kprintf("hammer2_unmount hmp=%p --mount_count=%d\n",
1452 				rchain->hmp, rchain->hmp->mount_count);
1453 			/* scrapping hmp now may invalidate the pmp */
1454 		}
1455 again:
1456 		TAILQ_FOREACH(hmp, &hammer2_mntlist, mntentry) {
1457 			if (hmp->mount_count == 0) {
1458 				hammer2_unmount_helper(NULL, NULL, hmp);
1459 				goto again;
1460 			}
1461 		}
1462 		return;
1463 	}
1464 
1465 	/*
1466 	 * Try to terminate the block device.  We can't terminate it if
1467 	 * there are still PFSs referencing it.
1468 	 */
1469 	kprintf("hammer2_unmount hmp=%p mount_count=%d\n",
1470 		hmp, hmp->mount_count);
1471 	if (hmp->mount_count)
1472 		return;
1473 
1474 	hammer2_pfsfree_scan(hmp);
1475 	hammer2_dev_exlock(hmp);	/* XXX order */
1476 
1477 	/*
1478 	 * Cycle the volume data lock as a safety (probably not needed any
1479 	 * more).  To ensure everything is out we need to flush at least
1480 	 * three times.  (1) The running of the sideq can dirty the
1481 	 * filesystem, (2) A normal flush can dirty the freemap, and
1482 	 * (3) ensure that the freemap is fully synchronized.
1483 	 *
1484 	 * The next mount's recovery scan can clean everything up but we want
1485 	 * to leave the filesystem in a 100% clean state on a normal unmount.
1486 	 */
1487 #if 0
1488 	hammer2_voldata_lock(hmp);
1489 	hammer2_voldata_unlock(hmp);
1490 #endif
1491 	hammer2_iocom_uninit(hmp);
1492 
1493 	if ((hmp->vchain.flags | hmp->fchain.flags) &
1494 	    HAMMER2_CHAIN_FLUSH_MASK) {
1495 		kprintf("hammer2_unmount: chains left over "
1496 			"after final sync\n");
1497 		kprintf("    vchain %08x\n", hmp->vchain.flags);
1498 		kprintf("    fchain %08x\n", hmp->fchain.flags);
1499 
1500 		if (hammer2_debug & 0x0010)
1501 			Debugger("entered debugger");
1502 	}
1503 
1504 	KKASSERT(hmp->spmp == NULL);
1505 
1506 	/*
1507 	 * Finish up with the device vnode
1508 	 */
1509 	if ((devvp = hmp->devvp) != NULL) {
1510 		vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
1511 		vinvalbuf(devvp, (ronly ? 0 : V_SAVE), 0, 0);
1512 		hmp->devvp = NULL;
1513 		VOP_CLOSE(devvp, (ronly ? FREAD : FREAD|FWRITE), NULL);
1514 		vn_unlock(devvp);
1515 		vrele(devvp);
1516 		devvp = NULL;
1517 	}
1518 
1519 	/*
1520 	 * Clear vchain/fchain flags that might prevent final cleanup
1521 	 * of these chains.
1522 	 */
1523 	if (hmp->vchain.flags & HAMMER2_CHAIN_MODIFIED) {
1524 		atomic_add_long(&hammer2_count_modified_chains, -1);
1525 		atomic_clear_int(&hmp->vchain.flags, HAMMER2_CHAIN_MODIFIED);
1526 		hammer2_pfs_memory_wakeup(hmp->vchain.pmp);
1527 	}
1528 	if (hmp->vchain.flags & HAMMER2_CHAIN_UPDATE) {
1529 		atomic_clear_int(&hmp->vchain.flags, HAMMER2_CHAIN_UPDATE);
1530 	}
1531 
1532 	if (hmp->fchain.flags & HAMMER2_CHAIN_MODIFIED) {
1533 		atomic_add_long(&hammer2_count_modified_chains, -1);
1534 		atomic_clear_int(&hmp->fchain.flags, HAMMER2_CHAIN_MODIFIED);
1535 		hammer2_pfs_memory_wakeup(hmp->fchain.pmp);
1536 	}
1537 	if (hmp->fchain.flags & HAMMER2_CHAIN_UPDATE) {
1538 		atomic_clear_int(&hmp->fchain.flags, HAMMER2_CHAIN_UPDATE);
1539 	}
1540 
1541 	/*
1542 	 * Final drop of embedded freemap root chain to
1543 	 * clean up fchain.core (fchain structure is not
1544 	 * flagged ALLOCATED so it is cleaned out and then
1545 	 * left to rot).
1546 	 */
1547 	hammer2_chain_drop(&hmp->fchain);
1548 
1549 	/*
1550 	 * Final drop of embedded volume root chain to clean
1551 	 * up vchain.core (vchain structure is not flagged
1552 	 * ALLOCATED so it is cleaned out and then left to
1553 	 * rot).
1554 	 */
1555 	dumpcnt = 50;
1556 	hammer2_dump_chain(&hmp->vchain, 0, &dumpcnt, 'v');
1557 	dumpcnt = 50;
1558 	hammer2_dump_chain(&hmp->fchain, 0, &dumpcnt, 'f');
1559 	hammer2_dev_unlock(hmp);
1560 	hammer2_chain_drop(&hmp->vchain);
1561 
1562 	hammer2_io_cleanup(hmp, &hmp->iotree);
1563 	if (hmp->iofree_count) {
1564 		kprintf("io_cleanup: %d I/O's left hanging\n",
1565 			hmp->iofree_count);
1566 	}
1567 
1568 	TAILQ_REMOVE(&hammer2_mntlist, hmp, mntentry);
1569 	kmalloc_destroy(&hmp->mchain);
1570 	kfree(hmp, M_HAMMER2);
1571 }
1572 
1573 static
1574 int
1575 hammer2_vfs_vget(struct mount *mp, struct vnode *dvp,
1576 	     ino_t ino, struct vnode **vpp)
1577 {
1578 	kprintf("hammer2_vget\n");
1579 	return (EOPNOTSUPP);
1580 }
1581 
1582 static
1583 int
1584 hammer2_vfs_root(struct mount *mp, struct vnode **vpp)
1585 {
1586 	hammer2_pfs_t *pmp;
1587 	int error;
1588 	struct vnode *vp;
1589 
1590 	pmp = MPTOPMP(mp);
1591 	if (pmp->iroot == NULL) {
1592 		*vpp = NULL;
1593 		return EINVAL;
1594 	}
1595 
1596 	error = 0;
1597 	hammer2_inode_lock(pmp->iroot, HAMMER2_RESOLVE_SHARED);
1598 
1599 	while (pmp->inode_tid == 0) {
1600 		hammer2_xop_ipcluster_t *xop;
1601 		hammer2_inode_meta_t *meta;
1602 
1603 		xop = hammer2_xop_alloc(pmp->iroot, HAMMER2_XOP_MODIFYING);
1604 		hammer2_xop_start(&xop->head, hammer2_xop_ipcluster);
1605 		error = hammer2_xop_collect(&xop->head, 0);
1606 
1607 		if (error == 0) {
1608 			meta = &xop->head.cluster.focus->data->ipdata.meta;
1609 			pmp->iroot->meta = *meta;
1610 			pmp->inode_tid = meta->pfs_inum + 1;
1611 			if (pmp->inode_tid < HAMMER2_INODE_START)
1612 				pmp->inode_tid = HAMMER2_INODE_START;
1613 			pmp->modify_tid =
1614 				xop->head.cluster.focus->bref.modify_tid + 1;
1615 			kprintf("PFS: Starting inode %jd\n",
1616 				(intmax_t)pmp->inode_tid);
1617 			kprintf("PMP focus good set nextino=%ld mod=%016jx\n",
1618 				pmp->inode_tid, pmp->modify_tid);
1619 			wakeup(&pmp->iroot);
1620 
1621 			hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
1622 
1623 			/*
1624 			 * Prime the mount info.
1625 			 */
1626 			hammer2_vfs_statfs(mp, &mp->mnt_stat, NULL);
1627 
1628 			/*
1629 			 * With the cluster operational, check for and
1630 			 * install ihidden if needed.  The install_hidden
1631 			 * code needs to get a transaction so we must unlock
1632 			 * iroot around it.
1633 			 *
1634 			 * This is only applicable PFS mounts, there is no
1635 			 * hidden directory in the spmp.
1636 			 */
1637 			hammer2_inode_unlock(pmp->iroot);
1638 			hammer2_inode_install_hidden(pmp);
1639 			hammer2_inode_lock(pmp->iroot, HAMMER2_RESOLVE_SHARED);
1640 
1641 			break;
1642 		}
1643 
1644 		/*
1645 		 * Loop, try again
1646 		 */
1647 		hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
1648 		hammer2_inode_unlock(pmp->iroot);
1649 		error = tsleep(&pmp->iroot, PCATCH, "h2root", hz);
1650 		hammer2_inode_lock(pmp->iroot, HAMMER2_RESOLVE_SHARED);
1651 		if (error == EINTR)
1652 			break;
1653 	}
1654 
1655 	if (error) {
1656 		hammer2_inode_unlock(pmp->iroot);
1657 		*vpp = NULL;
1658 	} else {
1659 		vp = hammer2_igetv(pmp->iroot, &error);
1660 		hammer2_inode_unlock(pmp->iroot);
1661 		*vpp = vp;
1662 	}
1663 
1664 	return (error);
1665 }
1666 
1667 /*
1668  * Filesystem status
1669  *
1670  * XXX incorporate ipdata->meta.inode_quota and data_quota
1671  */
1672 static
1673 int
1674 hammer2_vfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
1675 {
1676 	hammer2_pfs_t *pmp;
1677 	hammer2_dev_t *hmp;
1678 	hammer2_blockref_t bref;
1679 	int i;
1680 
1681 	/*
1682 	 * NOTE: iroot might not have validated the cluster yet.
1683 	 */
1684 	pmp = MPTOPMP(mp);
1685 
1686 	mp->mnt_stat.f_files = 0;
1687 	mp->mnt_stat.f_ffree = 0;
1688 	mp->mnt_stat.f_blocks = 0;
1689 	mp->mnt_stat.f_bfree = 0;
1690 	mp->mnt_stat.f_bavail = 0;
1691 
1692 	for (i = 0; i < pmp->iroot->cluster.nchains; ++i) {
1693 		hmp = pmp->pfs_hmps[i];
1694 		if (hmp == NULL)
1695 			continue;
1696 		if (pmp->iroot->cluster.array[i].chain)
1697 			bref = pmp->iroot->cluster.array[i].chain->bref;
1698 		else
1699 			bzero(&bref, sizeof(bref));
1700 
1701 		mp->mnt_stat.f_files = bref.inode_count;
1702 		mp->mnt_stat.f_ffree = 0;
1703 		mp->mnt_stat.f_blocks = (bref.data_count +
1704 					 hmp->voldata.allocator_free) /
1705 					mp->mnt_vstat.f_bsize;
1706 		mp->mnt_stat.f_bfree =  hmp->voldata.allocator_free /
1707 					mp->mnt_vstat.f_bsize;
1708 		mp->mnt_stat.f_bavail = mp->mnt_stat.f_bfree;
1709 
1710 		*sbp = mp->mnt_stat;
1711 	}
1712 	return (0);
1713 }
1714 
1715 static
1716 int
1717 hammer2_vfs_statvfs(struct mount *mp, struct statvfs *sbp, struct ucred *cred)
1718 {
1719 	hammer2_pfs_t *pmp;
1720 	hammer2_dev_t *hmp;
1721 	hammer2_blockref_t bref;
1722 	int i;
1723 
1724 	/*
1725 	 * NOTE: iroot might not have validated the cluster yet.
1726 	 */
1727 	pmp = MPTOPMP(mp);
1728 
1729 	mp->mnt_vstat.f_bsize = 0;
1730 	mp->mnt_vstat.f_files = 0;
1731 	mp->mnt_vstat.f_ffree = 0;
1732 	mp->mnt_vstat.f_blocks = 0;
1733 	mp->mnt_vstat.f_bfree = 0;
1734 	mp->mnt_vstat.f_bavail = 0;
1735 
1736 	for (i = 0; i < pmp->iroot->cluster.nchains; ++i) {
1737 		hmp = pmp->pfs_hmps[i];
1738 		if (hmp == NULL)
1739 			continue;
1740 		if (pmp->iroot->cluster.array[i].chain)
1741 			bref = pmp->iroot->cluster.array[i].chain->bref;
1742 		else
1743 			bzero(&bref, sizeof(bref));
1744 
1745 		mp->mnt_vstat.f_bsize = HAMMER2_PBUFSIZE;
1746 		mp->mnt_vstat.f_files = bref.inode_count;
1747 		mp->mnt_vstat.f_ffree = 0;
1748 		mp->mnt_vstat.f_blocks = (bref.data_count +
1749 					 hmp->voldata.allocator_free) /
1750 					mp->mnt_vstat.f_bsize;
1751 		mp->mnt_vstat.f_bfree = hmp->voldata.allocator_free /
1752 					mp->mnt_vstat.f_bsize;
1753 		mp->mnt_vstat.f_bavail = mp->mnt_vstat.f_bfree;
1754 
1755 		*sbp = mp->mnt_vstat;
1756 	}
1757 	return (0);
1758 }
1759 
1760 /*
1761  * Mount-time recovery (RW mounts)
1762  *
1763  * Updates to the free block table are allowed to lag flushes by one
1764  * transaction.  In case of a crash, then on a fresh mount we must do an
1765  * incremental scan of the last committed transaction id and make sure that
1766  * all related blocks have been marked allocated.
1767  *
1768  * The super-root topology and each PFS has its own transaction id domain,
1769  * so we must track PFS boundary transitions.
1770  */
1771 struct hammer2_recovery_elm {
1772 	TAILQ_ENTRY(hammer2_recovery_elm) entry;
1773 	hammer2_chain_t *chain;
1774 	hammer2_tid_t sync_tid;
1775 };
1776 
1777 TAILQ_HEAD(hammer2_recovery_list, hammer2_recovery_elm);
1778 
1779 struct hammer2_recovery_info {
1780 	struct hammer2_recovery_list list;
1781 	hammer2_tid_t	mtid;
1782 	int	depth;
1783 };
1784 
1785 static int hammer2_recovery_scan(hammer2_dev_t *hmp,
1786 			hammer2_chain_t *parent,
1787 			struct hammer2_recovery_info *info,
1788 			hammer2_tid_t sync_tid);
1789 
1790 #define HAMMER2_RECOVERY_MAXDEPTH	10
1791 
1792 static
1793 int
1794 hammer2_recovery(hammer2_dev_t *hmp)
1795 {
1796 	struct hammer2_recovery_info info;
1797 	struct hammer2_recovery_elm *elm;
1798 	hammer2_chain_t *parent;
1799 	hammer2_tid_t sync_tid;
1800 	hammer2_tid_t mirror_tid;
1801 	int error;
1802 	int cumulative_error = 0;
1803 
1804 	hammer2_trans_init(hmp->spmp, 0);
1805 
1806 	sync_tid = hmp->voldata.freemap_tid;
1807 	mirror_tid = hmp->voldata.mirror_tid;
1808 
1809 	kprintf("hammer2 mount \"%s\": ", hmp->devrepname);
1810 	if (sync_tid >= mirror_tid) {
1811 		kprintf(" no recovery needed\n");
1812 	} else {
1813 		kprintf(" freemap recovery %016jx-%016jx\n",
1814 			sync_tid + 1, mirror_tid);
1815 	}
1816 
1817 	TAILQ_INIT(&info.list);
1818 	info.depth = 0;
1819 	parent = hammer2_chain_lookup_init(&hmp->vchain, 0);
1820 	cumulative_error = hammer2_recovery_scan(hmp, parent, &info, sync_tid);
1821 	hammer2_chain_lookup_done(parent);
1822 
1823 	while ((elm = TAILQ_FIRST(&info.list)) != NULL) {
1824 		TAILQ_REMOVE(&info.list, elm, entry);
1825 		parent = elm->chain;
1826 		sync_tid = elm->sync_tid;
1827 		kfree(elm, M_HAMMER2);
1828 
1829 		hammer2_chain_lock(parent, HAMMER2_RESOLVE_ALWAYS);
1830 		error = hammer2_recovery_scan(hmp, parent, &info,
1831 					      hmp->voldata.freemap_tid);
1832 		hammer2_chain_unlock(parent);
1833 		hammer2_chain_drop(parent);	/* drop elm->chain ref */
1834 		if (error)
1835 			cumulative_error = error;
1836 	}
1837 	hammer2_trans_done(hmp->spmp);
1838 
1839 	return cumulative_error;
1840 }
1841 
1842 static
1843 int
1844 hammer2_recovery_scan(hammer2_dev_t *hmp, hammer2_chain_t *parent,
1845 		      struct hammer2_recovery_info *info,
1846 		      hammer2_tid_t sync_tid)
1847 {
1848 	const hammer2_inode_data_t *ripdata;
1849 	hammer2_chain_t *chain;
1850 	hammer2_blockref_t bref;
1851 	int cache_index;
1852 	int cumulative_error = 0;
1853 	int error;
1854 	int first;
1855 
1856 	/*
1857 	 * Adjust freemap to ensure that the block(s) are marked allocated.
1858 	 */
1859 	if (parent->bref.type != HAMMER2_BREF_TYPE_VOLUME) {
1860 		hammer2_freemap_adjust(hmp, &parent->bref,
1861 				       HAMMER2_FREEMAP_DORECOVER);
1862 	}
1863 
1864 	/*
1865 	 * Check type for recursive scan
1866 	 */
1867 	switch(parent->bref.type) {
1868 	case HAMMER2_BREF_TYPE_VOLUME:
1869 		/* data already instantiated */
1870 		break;
1871 	case HAMMER2_BREF_TYPE_INODE:
1872 		/*
1873 		 * Must instantiate data for DIRECTDATA test and also
1874 		 * for recursion.
1875 		 */
1876 		hammer2_chain_lock(parent, HAMMER2_RESOLVE_ALWAYS);
1877 		ripdata = &hammer2_chain_rdata(parent)->ipdata;
1878 		if (ripdata->meta.op_flags & HAMMER2_OPFLAG_DIRECTDATA) {
1879 			/* not applicable to recovery scan */
1880 			hammer2_chain_unlock(parent);
1881 			return 0;
1882 		}
1883 		hammer2_chain_unlock(parent);
1884 		break;
1885 	case HAMMER2_BREF_TYPE_INDIRECT:
1886 		/*
1887 		 * Must instantiate data for recursion
1888 		 */
1889 		hammer2_chain_lock(parent, HAMMER2_RESOLVE_ALWAYS);
1890 		hammer2_chain_unlock(parent);
1891 		break;
1892 	case HAMMER2_BREF_TYPE_DATA:
1893 	case HAMMER2_BREF_TYPE_FREEMAP:
1894 	case HAMMER2_BREF_TYPE_FREEMAP_NODE:
1895 	case HAMMER2_BREF_TYPE_FREEMAP_LEAF:
1896 		/* not applicable to recovery scan */
1897 		return 0;
1898 		break;
1899 	default:
1900 		return EDOM;
1901 	}
1902 
1903 	/*
1904 	 * Defer operation if depth limit reached or if we are crossing a
1905 	 * PFS boundary.
1906 	 */
1907 	if (info->depth >= HAMMER2_RECOVERY_MAXDEPTH) {
1908 		struct hammer2_recovery_elm *elm;
1909 
1910 		elm = kmalloc(sizeof(*elm), M_HAMMER2, M_ZERO | M_WAITOK);
1911 		elm->chain = parent;
1912 		elm->sync_tid = sync_tid;
1913 		hammer2_chain_ref(parent);
1914 		TAILQ_INSERT_TAIL(&info->list, elm, entry);
1915 		/* unlocked by caller */
1916 
1917 		return(0);
1918 	}
1919 
1920 
1921 	/*
1922 	 * Recursive scan of the last flushed transaction only.  We are
1923 	 * doing this without pmp assignments so don't leave the chains
1924 	 * hanging around after we are done with them.
1925 	 */
1926 	cache_index = 0;
1927 	chain = NULL;
1928 	first = 1;
1929 
1930 	while (hammer2_chain_scan(parent, &chain, &bref,
1931 				  &first, &cache_index,
1932 				  HAMMER2_LOOKUP_NODATA) != NULL) {
1933 		/*
1934 		 * If this is a leaf
1935 		 */
1936 		if (chain == NULL) {
1937 			if (bref.mirror_tid > sync_tid) {
1938 				hammer2_freemap_adjust(hmp, &bref,
1939 						     HAMMER2_FREEMAP_DORECOVER);
1940 			}
1941 			continue;
1942 		}
1943 
1944 		/*
1945 		 * This may or may not be a recursive node.
1946 		 */
1947 		atomic_set_int(&chain->flags, HAMMER2_CHAIN_RELEASE);
1948 		if (bref.mirror_tid > sync_tid) {
1949 			++info->depth;
1950 			error = hammer2_recovery_scan(hmp, chain,
1951 						      info, sync_tid);
1952 			--info->depth;
1953 			if (error)
1954 				cumulative_error = error;
1955 		}
1956 
1957 		/*
1958 		 * Flush the recovery at the PFS boundary to stage it for
1959 		 * the final flush of the super-root topology.
1960 		 */
1961 		if ((bref.flags & HAMMER2_BREF_FLAG_PFSROOT) &&
1962 		    (chain->flags & HAMMER2_CHAIN_ONFLUSH)) {
1963 			hammer2_flush(chain, HAMMER2_FLUSH_TOP);
1964 		}
1965 	}
1966 
1967 	return cumulative_error;
1968 }
1969 
1970 /*
1971  * Sync a mount point; this is called on a per-mount basis from the
1972  * filesystem syncer process periodically and whenever a user issues
1973  * a sync.
1974  */
1975 int
1976 hammer2_vfs_sync(struct mount *mp, int waitfor)
1977 {
1978 	hammer2_xop_flush_t *xop;
1979 	struct hammer2_sync_info info;
1980 	hammer2_inode_t *iroot;
1981 	hammer2_pfs_t *pmp;
1982 	int flags;
1983 	int error;
1984 
1985 	pmp = MPTOPMP(mp);
1986 	iroot = pmp->iroot;
1987 	KKASSERT(iroot);
1988 	KKASSERT(iroot->pmp == pmp);
1989 
1990 	/*
1991 	 * We can't acquire locks on existing vnodes while in a transaction
1992 	 * without risking a deadlock.  This assumes that vfsync() can be
1993 	 * called without the vnode locked (which it can in DragonFly).
1994 	 * Otherwise we'd have to implement a multi-pass or flag the lock
1995 	 * failures and retry.
1996 	 *
1997 	 * The reclamation code interlocks with the sync list's token
1998 	 * (by removing the vnode from the scan list) before unlocking
1999 	 * the inode, giving us time to ref the inode.
2000 	 */
2001 	/*flags = VMSC_GETVP;*/
2002 	flags = 0;
2003 	if (waitfor & MNT_LAZY)
2004 		flags |= VMSC_ONEPASS;
2005 
2006 #if 0
2007 	/*
2008 	 * Preflush the vnodes using a normal transaction before interlocking
2009 	 * with a flush transaction.
2010 	 */
2011 	hammer2_trans_init(pmp, 0);
2012 	info.error = 0;
2013 	info.waitfor = MNT_NOWAIT;
2014 	vsyncscan(mp, flags | VMSC_NOWAIT, hammer2_sync_scan2, &info);
2015 	hammer2_trans_done(pmp);
2016 #endif
2017 
2018 	/*
2019 	 * Start our flush transaction.  This does not return until all
2020 	 * concurrent transactions have completed and will prevent any
2021 	 * new transactions from running concurrently, except for the
2022 	 * buffer cache transactions.
2023 	 *
2024 	 * For efficiency do an async pass before making sure with a
2025 	 * synchronous pass on all related buffer cache buffers.  It
2026 	 * should theoretically not be possible for any new file buffers
2027 	 * to be instantiated during this sequence.
2028 	 */
2029 	hammer2_trans_init(pmp, HAMMER2_TRANS_ISFLUSH |
2030 			        HAMMER2_TRANS_PREFLUSH);
2031 	hammer2_inode_run_sideq(pmp);
2032 
2033 	info.error = 0;
2034 	info.waitfor = MNT_NOWAIT;
2035 	vsyncscan(mp, flags | VMSC_NOWAIT, hammer2_sync_scan2, &info);
2036 	info.waitfor = MNT_WAIT;
2037 	vsyncscan(mp, flags, hammer2_sync_scan2, &info);
2038 
2039 	/*
2040 	 * Clear PREFLUSH.  This prevents (or asserts on) any new logical
2041 	 * buffer cache flushes which occur during the flush.  Device buffers
2042 	 * are not affected.
2043 	 */
2044 	hammer2_bioq_sync(pmp);
2045 	hammer2_trans_clear_preflush(pmp);
2046 
2047 	/*
2048 	 * Use the XOP interface to concurrently flush all nodes to
2049 	 * synchronize the PFSROOT subtopology to the media.  A standard
2050 	 * end-of-scan ENOENT error indicates cluster sufficiency.
2051 	 *
2052 	 * Note that this flush will not be visible on crash recovery until
2053 	 * we flush the super-root topology in the next loop.
2054 	 *
2055 	 * XXX For now wait for all flushes to complete.
2056 	 */
2057 	if (iroot) {
2058 		xop = hammer2_xop_alloc(iroot, HAMMER2_XOP_MODIFYING);
2059 		hammer2_xop_start(&xop->head, hammer2_inode_xop_flush);
2060 		error = hammer2_xop_collect(&xop->head,
2061 					    HAMMER2_XOP_COLLECT_WAITALL);
2062 		hammer2_xop_retire(&xop->head, HAMMER2_XOPMASK_VOP);
2063 		if (error == ENOENT)
2064 			error = 0;
2065 	} else {
2066 		error = 0;
2067 	}
2068 	hammer2_trans_done(pmp);
2069 
2070 	return (error);
2071 }
2072 
2073 /*
2074  * Sync passes.
2075  *
2076  * Note that we ignore the tranasction mtid we got above.  Instead,
2077  * each vfsync below will ultimately get its own via TRANS_BUFCACHE
2078  * transactions.
2079  */
2080 static int
2081 hammer2_sync_scan2(struct mount *mp, struct vnode *vp, void *data)
2082 {
2083 	struct hammer2_sync_info *info = data;
2084 	hammer2_inode_t *ip;
2085 	int error;
2086 
2087 	/*
2088 	 * Degenerate cases.  Note that ip == NULL typically means the
2089 	 * syncer vnode itself and we don't want to vclrisdirty() in that
2090 	 * situation.
2091 	 */
2092 	ip = VTOI(vp);
2093 	if (ip == NULL) {
2094 		return(0);
2095 	}
2096 	if (vp->v_type == VNON || vp->v_type == VBAD) {
2097 		vclrisdirty(vp);
2098 		return(0);
2099 	}
2100 
2101 	/*
2102 	 * VOP_FSYNC will start a new transaction so replicate some code
2103 	 * here to do it inline (see hammer2_vop_fsync()).
2104 	 *
2105 	 * WARNING: The vfsync interacts with the buffer cache and might
2106 	 *          block, we can't hold the inode lock at that time.
2107 	 *	    However, we MUST ref ip before blocking to ensure that
2108 	 *	    it isn't ripped out from under us (since we do not
2109 	 *	    hold a lock on the vnode).
2110 	 */
2111 	hammer2_inode_ref(ip);
2112 	if ((ip->flags & HAMMER2_INODE_MODIFIED) ||
2113 	    !RB_EMPTY(&vp->v_rbdirty_tree)) {
2114 		vfsync(vp, info->waitfor, 1, NULL, NULL);
2115 		if (ip->flags & (HAMMER2_INODE_RESIZED |
2116 				 HAMMER2_INODE_MODIFIED)) {
2117 			hammer2_inode_lock(ip, 0);
2118 			hammer2_inode_chain_sync(ip);
2119 			hammer2_inode_unlock(ip);
2120 		}
2121 	}
2122 	if ((ip->flags & HAMMER2_INODE_MODIFIED) == 0 &&
2123 	    RB_EMPTY(&vp->v_rbdirty_tree)) {
2124 		vclrisdirty(vp);
2125 	}
2126 
2127 	hammer2_inode_drop(ip);
2128 #if 1
2129 	error = 0;
2130 	if (error)
2131 		info->error = error;
2132 #endif
2133 	return(0);
2134 }
2135 
2136 static
2137 int
2138 hammer2_vfs_vptofh(struct vnode *vp, struct fid *fhp)
2139 {
2140 	return (0);
2141 }
2142 
2143 static
2144 int
2145 hammer2_vfs_fhtovp(struct mount *mp, struct vnode *rootvp,
2146 	       struct fid *fhp, struct vnode **vpp)
2147 {
2148 	return (0);
2149 }
2150 
2151 static
2152 int
2153 hammer2_vfs_checkexp(struct mount *mp, struct sockaddr *nam,
2154 		 int *exflagsp, struct ucred **credanonp)
2155 {
2156 	return (0);
2157 }
2158 
2159 /*
2160  * Support code for hammer2_vfs_mount().  Read, verify, and install the volume
2161  * header into the HMP
2162  *
2163  * XXX read four volhdrs and use the one with the highest TID whos CRC
2164  *     matches.
2165  *
2166  * XXX check iCRCs.
2167  *
2168  * XXX For filesystems w/ less than 4 volhdrs, make sure to not write to
2169  *     nonexistant locations.
2170  *
2171  * XXX Record selected volhdr and ring updates to each of 4 volhdrs
2172  */
2173 static
2174 int
2175 hammer2_install_volume_header(hammer2_dev_t *hmp)
2176 {
2177 	hammer2_volume_data_t *vd;
2178 	struct buf *bp;
2179 	hammer2_crc32_t crc0, crc, bcrc0, bcrc;
2180 	int error_reported;
2181 	int error;
2182 	int valid;
2183 	int i;
2184 
2185 	error_reported = 0;
2186 	error = 0;
2187 	valid = 0;
2188 	bp = NULL;
2189 
2190 	/*
2191 	 * There are up to 4 copies of the volume header (syncs iterate
2192 	 * between them so there is no single master).  We don't trust the
2193 	 * volu_size field so we don't know precisely how large the filesystem
2194 	 * is, so depend on the OS to return an error if we go beyond the
2195 	 * block device's EOF.
2196 	 */
2197 	for (i = 0; i < HAMMER2_NUM_VOLHDRS; i++) {
2198 		error = bread(hmp->devvp, i * HAMMER2_ZONE_BYTES64,
2199 			      HAMMER2_VOLUME_BYTES, &bp);
2200 		if (error) {
2201 			brelse(bp);
2202 			bp = NULL;
2203 			continue;
2204 		}
2205 
2206 		vd = (struct hammer2_volume_data *) bp->b_data;
2207 		if ((vd->magic != HAMMER2_VOLUME_ID_HBO) &&
2208 		    (vd->magic != HAMMER2_VOLUME_ID_ABO)) {
2209 			brelse(bp);
2210 			bp = NULL;
2211 			continue;
2212 		}
2213 
2214 		if (vd->magic == HAMMER2_VOLUME_ID_ABO) {
2215 			/* XXX: Reversed-endianness filesystem */
2216 			kprintf("hammer2: reverse-endian filesystem detected");
2217 			brelse(bp);
2218 			bp = NULL;
2219 			continue;
2220 		}
2221 
2222 		crc = vd->icrc_sects[HAMMER2_VOL_ICRC_SECT0];
2223 		crc0 = hammer2_icrc32(bp->b_data + HAMMER2_VOLUME_ICRC0_OFF,
2224 				      HAMMER2_VOLUME_ICRC0_SIZE);
2225 		bcrc = vd->icrc_sects[HAMMER2_VOL_ICRC_SECT1];
2226 		bcrc0 = hammer2_icrc32(bp->b_data + HAMMER2_VOLUME_ICRC1_OFF,
2227 				       HAMMER2_VOLUME_ICRC1_SIZE);
2228 		if ((crc0 != crc) || (bcrc0 != bcrc)) {
2229 			kprintf("hammer2 volume header crc "
2230 				"mismatch copy #%d %08x/%08x\n",
2231 				i, crc0, crc);
2232 			error_reported = 1;
2233 			brelse(bp);
2234 			bp = NULL;
2235 			continue;
2236 		}
2237 		if (valid == 0 || hmp->voldata.mirror_tid < vd->mirror_tid) {
2238 			valid = 1;
2239 			hmp->voldata = *vd;
2240 			hmp->volhdrno = i;
2241 		}
2242 		brelse(bp);
2243 		bp = NULL;
2244 	}
2245 	if (valid) {
2246 		hmp->volsync = hmp->voldata;
2247 		error = 0;
2248 		if (error_reported || bootverbose || 1) { /* 1/DEBUG */
2249 			kprintf("hammer2: using volume header #%d\n",
2250 				hmp->volhdrno);
2251 		}
2252 	} else {
2253 		error = EINVAL;
2254 		kprintf("hammer2: no valid volume headers found!\n");
2255 	}
2256 	return (error);
2257 }
2258 
2259 /*
2260  * This handles hysteresis on regular file flushes.  Because the BIOs are
2261  * routed to a thread it is possible for an excessive number to build up
2262  * and cause long front-end stalls long before the runningbuffspace limit
2263  * is hit, so we implement hammer2_flush_pipe to control the
2264  * hysteresis.
2265  *
2266  * This is a particular problem when compression is used.
2267  */
2268 void
2269 hammer2_lwinprog_ref(hammer2_pfs_t *pmp)
2270 {
2271 	atomic_add_int(&pmp->count_lwinprog, 1);
2272 }
2273 
2274 void
2275 hammer2_lwinprog_drop(hammer2_pfs_t *pmp)
2276 {
2277 	int lwinprog;
2278 
2279 	lwinprog = atomic_fetchadd_int(&pmp->count_lwinprog, -1);
2280 	if ((lwinprog & HAMMER2_LWINPROG_WAITING) &&
2281 	    (lwinprog & HAMMER2_LWINPROG_MASK) <= hammer2_flush_pipe * 2 / 3) {
2282 		atomic_clear_int(&pmp->count_lwinprog,
2283 				 HAMMER2_LWINPROG_WAITING);
2284 		wakeup(&pmp->count_lwinprog);
2285 	}
2286 	if ((lwinprog & HAMMER2_LWINPROG_WAITING0) &&
2287 	    (lwinprog & HAMMER2_LWINPROG_MASK) <= 0) {
2288 		atomic_clear_int(&pmp->count_lwinprog,
2289 				 HAMMER2_LWINPROG_WAITING0);
2290 		wakeup(&pmp->count_lwinprog);
2291 	}
2292 }
2293 
2294 void
2295 hammer2_lwinprog_wait(hammer2_pfs_t *pmp, int flush_pipe)
2296 {
2297 	int lwinprog;
2298 	int lwflag = (flush_pipe) ? HAMMER2_LWINPROG_WAITING :
2299 				    HAMMER2_LWINPROG_WAITING0;
2300 
2301 	for (;;) {
2302 		lwinprog = pmp->count_lwinprog;
2303 		cpu_ccfence();
2304 		if ((lwinprog & HAMMER2_LWINPROG_MASK) <= flush_pipe)
2305 			break;
2306 		tsleep_interlock(&pmp->count_lwinprog, 0);
2307 		atomic_set_int(&pmp->count_lwinprog, lwflag);
2308 		lwinprog = pmp->count_lwinprog;
2309 		if ((lwinprog & HAMMER2_LWINPROG_MASK) <= flush_pipe)
2310 			break;
2311 		tsleep(&pmp->count_lwinprog, PINTERLOCKED, "h2wpipe", hz);
2312 	}
2313 }
2314 
2315 /*
2316  * Manage excessive memory resource use for chain and related
2317  * structures.
2318  */
2319 void
2320 hammer2_pfs_memory_wait(hammer2_pfs_t *pmp)
2321 {
2322 	uint32_t waiting;
2323 	uint32_t count;
2324 	uint32_t limit;
2325 #if 0
2326 	static int zzticks;
2327 #endif
2328 
2329 	/*
2330 	 * Atomic check condition and wait.  Also do an early speedup of
2331 	 * the syncer to try to avoid hitting the wait.
2332 	 */
2333 	for (;;) {
2334 		waiting = pmp->inmem_dirty_chains;
2335 		cpu_ccfence();
2336 		count = waiting & HAMMER2_DIRTYCHAIN_MASK;
2337 
2338 		limit = pmp->mp->mnt_nvnodelistsize / 10;
2339 		if (limit < hammer2_limit_dirty_chains)
2340 			limit = hammer2_limit_dirty_chains;
2341 		if (limit < 1000)
2342 			limit = 1000;
2343 
2344 #if 0
2345 		if ((int)(ticks - zzticks) > hz) {
2346 			zzticks = ticks;
2347 			kprintf("count %ld %ld\n", count, limit);
2348 		}
2349 #endif
2350 
2351 		/*
2352 		 * Block if there are too many dirty chains present, wait
2353 		 * for the flush to clean some out.
2354 		 */
2355 		if (count > limit) {
2356 			tsleep_interlock(&pmp->inmem_dirty_chains, 0);
2357 			if (atomic_cmpset_int(&pmp->inmem_dirty_chains,
2358 					       waiting,
2359 				       waiting | HAMMER2_DIRTYCHAIN_WAITING)) {
2360 				speedup_syncer(pmp->mp);
2361 				tsleep(&pmp->inmem_dirty_chains, PINTERLOCKED,
2362 				       "chnmem", hz);
2363 			}
2364 			continue;	/* loop on success or fail */
2365 		}
2366 
2367 		/*
2368 		 * Try to start an early flush before we are forced to block.
2369 		 */
2370 		if (count > limit * 7 / 10)
2371 			speedup_syncer(pmp->mp);
2372 		break;
2373 	}
2374 }
2375 
2376 void
2377 hammer2_pfs_memory_inc(hammer2_pfs_t *pmp)
2378 {
2379 	if (pmp) {
2380 		atomic_add_int(&pmp->inmem_dirty_chains, 1);
2381 	}
2382 }
2383 
2384 void
2385 hammer2_pfs_memory_wakeup(hammer2_pfs_t *pmp)
2386 {
2387 	uint32_t waiting;
2388 
2389 	if (pmp == NULL)
2390 		return;
2391 
2392 	for (;;) {
2393 		waiting = pmp->inmem_dirty_chains;
2394 		cpu_ccfence();
2395 		if (atomic_cmpset_int(&pmp->inmem_dirty_chains,
2396 				       waiting,
2397 				       (waiting - 1) &
2398 					~HAMMER2_DIRTYCHAIN_WAITING)) {
2399 			break;
2400 		}
2401 	}
2402 
2403 	if (waiting & HAMMER2_DIRTYCHAIN_WAITING)
2404 		wakeup(&pmp->inmem_dirty_chains);
2405 }
2406 
2407 /*
2408  * Debugging
2409  */
2410 void
2411 hammer2_dump_chain(hammer2_chain_t *chain, int tab, int *countp, char pfx)
2412 {
2413 	hammer2_chain_t *scan;
2414 	hammer2_chain_t *parent;
2415 
2416 	--*countp;
2417 	if (*countp == 0) {
2418 		kprintf("%*.*s...\n", tab, tab, "");
2419 		return;
2420 	}
2421 	if (*countp < 0)
2422 		return;
2423 	kprintf("%*.*s%c-chain %p.%d %016jx/%d mir=%016jx\n",
2424 		tab, tab, "", pfx,
2425 		chain, chain->bref.type,
2426 		chain->bref.key, chain->bref.keybits,
2427 		chain->bref.mirror_tid);
2428 
2429 	kprintf("%*.*s      [%08x] (%s) refs=%d",
2430 		tab, tab, "",
2431 		chain->flags,
2432 		((chain->bref.type == HAMMER2_BREF_TYPE_INODE &&
2433 		chain->data) ?  (char *)chain->data->ipdata.filename : "?"),
2434 		chain->refs);
2435 
2436 	parent = chain->parent;
2437 	if (parent)
2438 		kprintf("\n%*.*s      p=%p [pflags %08x prefs %d",
2439 			tab, tab, "",
2440 			parent, parent->flags, parent->refs);
2441 	if (RB_EMPTY(&chain->core.rbtree)) {
2442 		kprintf("\n");
2443 	} else {
2444 		kprintf(" {\n");
2445 		RB_FOREACH(scan, hammer2_chain_tree, &chain->core.rbtree)
2446 			hammer2_dump_chain(scan, tab + 4, countp, 'a');
2447 		if (chain->bref.type == HAMMER2_BREF_TYPE_INODE && chain->data)
2448 			kprintf("%*.*s}(%s)\n", tab, tab, "",
2449 				chain->data->ipdata.filename);
2450 		else
2451 			kprintf("%*.*s}\n", tab, tab, "");
2452 	}
2453 }
2454