1/* Copyright (c) 2013 Coraid, Inc.  See COPYING for GPL terms. */
2/*
3 * aoedev.c
4 * AoE device utility functions; maintains device list.
5 */
6
7#include <linux/hdreg.h>
8#include <linux/blk-mq.h>
9#include <linux/netdevice.h>
10#include <linux/delay.h>
11#include <linux/slab.h>
12#include <linux/bitmap.h>
13#include <linux/kdev_t.h>
14#include <linux/moduleparam.h>
15#include <linux/string.h>
16#include "aoe.h"
17
18static void freetgt(struct aoedev *d, struct aoetgt *t);
19static void skbpoolfree(struct aoedev *d);
20
21static int aoe_dyndevs = 1;
22module_param(aoe_dyndevs, int, 0644);
23MODULE_PARM_DESC(aoe_dyndevs, "Use dynamic minor numbers for devices.");
24
25static struct aoedev *devlist;
26static DEFINE_SPINLOCK(devlist_lock);
27
28/* Because some systems will have one, many, or no
29 *   - partitions,
30 *   - slots per shelf,
31 *   - or shelves,
32 * we need some flexibility in the way the minor numbers
33 * are allocated.  So they are dynamic.
34 */
35#define N_DEVS ((1U<<MINORBITS)/AOE_PARTITIONS)
36
37static DEFINE_SPINLOCK(used_minors_lock);
38static DECLARE_BITMAP(used_minors, N_DEVS);
39
40static int
41minor_get_dyn(ulong *sysminor)
42{
43	ulong flags;
44	ulong n;
45	int error = 0;
46
47	spin_lock_irqsave(&used_minors_lock, flags);
48	n = find_first_zero_bit(used_minors, N_DEVS);
49	if (n < N_DEVS)
50		set_bit(n, used_minors);
51	else
52		error = -1;
53	spin_unlock_irqrestore(&used_minors_lock, flags);
54
55	*sysminor = n * AOE_PARTITIONS;
56	return error;
57}
58
59static int
60minor_get_static(ulong *sysminor, ulong aoemaj, int aoemin)
61{
62	ulong flags;
63	ulong n;
64	int error = 0;
65	enum {
66		/* for backwards compatibility when !aoe_dyndevs,
67		 * a static number of supported slots per shelf */
68		NPERSHELF = 16,
69	};
70
71	if (aoemin >= NPERSHELF) {
72		pr_err("aoe: %s %d slots per shelf\n",
73			"static minor device numbers support only",
74			NPERSHELF);
75		error = -1;
76		goto out;
77	}
78
79	n = aoemaj * NPERSHELF + aoemin;
80	if (n >= N_DEVS) {
81		pr_err("aoe: %s with e%ld.%d\n",
82			"cannot use static minor device numbers",
83			aoemaj, aoemin);
84		error = -1;
85		goto out;
86	}
87
88	spin_lock_irqsave(&used_minors_lock, flags);
89	if (test_bit(n, used_minors)) {
90		pr_err("aoe: %s %lu\n",
91			"existing device already has static minor number",
92			n);
93		error = -1;
94	} else
95		set_bit(n, used_minors);
96	spin_unlock_irqrestore(&used_minors_lock, flags);
97	*sysminor = n * AOE_PARTITIONS;
98out:
99	return error;
100}
101
102static int
103minor_get(ulong *sysminor, ulong aoemaj, int aoemin)
104{
105	if (aoe_dyndevs)
106		return minor_get_dyn(sysminor);
107	else
108		return minor_get_static(sysminor, aoemaj, aoemin);
109}
110
111static void
112minor_free(ulong minor)
113{
114	ulong flags;
115
116	minor /= AOE_PARTITIONS;
117	BUG_ON(minor >= N_DEVS);
118
119	spin_lock_irqsave(&used_minors_lock, flags);
120	BUG_ON(!test_bit(minor, used_minors));
121	clear_bit(minor, used_minors);
122	spin_unlock_irqrestore(&used_minors_lock, flags);
123}
124
125/*
126 * Users who grab a pointer to the device with aoedev_by_aoeaddr
127 * automatically get a reference count and must be responsible
128 * for performing a aoedev_put.  With the addition of async
129 * kthread processing I'm no longer confident that we can
130 * guarantee consistency in the face of device flushes.
131 *
132 * For the time being, we only bother to add extra references for
133 * frames sitting on the iocq.  When the kthreads finish processing
134 * these frames, they will aoedev_put the device.
135 */
136
137void
138aoedev_put(struct aoedev *d)
139{
140	ulong flags;
141
142	spin_lock_irqsave(&devlist_lock, flags);
143	d->ref--;
144	spin_unlock_irqrestore(&devlist_lock, flags);
145}
146
147static void
148dummy_timer(struct timer_list *t)
149{
150	struct aoedev *d;
151
152	d = from_timer(d, t, timer);
153	if (d->flags & DEVFL_TKILL)
154		return;
155	d->timer.expires = jiffies + HZ;
156	add_timer(&d->timer);
157}
158
159static void
160aoe_failip(struct aoedev *d)
161{
162	struct request *rq;
163	struct aoe_req *req;
164	struct bio *bio;
165
166	aoe_failbuf(d, d->ip.buf);
167	rq = d->ip.rq;
168	if (rq == NULL)
169		return;
170
171	req = blk_mq_rq_to_pdu(rq);
172	while ((bio = d->ip.nxbio)) {
173		bio->bi_status = BLK_STS_IOERR;
174		d->ip.nxbio = bio->bi_next;
175		req->nr_bios--;
176	}
177
178	if (!req->nr_bios)
179		aoe_end_request(d, rq, 0);
180}
181
182static void
183downdev_frame(struct list_head *pos)
184{
185	struct frame *f;
186
187	f = list_entry(pos, struct frame, head);
188	list_del(pos);
189	if (f->buf) {
190		f->buf->nframesout--;
191		aoe_failbuf(f->t->d, f->buf);
192	}
193	aoe_freetframe(f);
194}
195
196void
197aoedev_downdev(struct aoedev *d)
198{
199	struct aoetgt *t, **tt, **te;
200	struct list_head *head, *pos, *nx;
201	int i;
202
203	d->flags &= ~DEVFL_UP;
204
205	/* clean out active and to-be-retransmitted buffers */
206	for (i = 0; i < NFACTIVE; i++) {
207		head = &d->factive[i];
208		list_for_each_safe(pos, nx, head)
209			downdev_frame(pos);
210	}
211	head = &d->rexmitq;
212	list_for_each_safe(pos, nx, head)
213		downdev_frame(pos);
214
215	/* reset window dressings */
216	tt = d->targets;
217	te = tt + d->ntargets;
218	for (; tt < te && (t = *tt); tt++) {
219		aoecmd_wreset(t);
220		t->nout = 0;
221	}
222
223	/* clean out the in-process request (if any) */
224	aoe_failip(d);
225
226	/* fast fail all pending I/O */
227	if (d->blkq) {
228		/* UP is cleared, freeze+quiesce to insure all are errored */
229		blk_mq_freeze_queue(d->blkq);
230		blk_mq_quiesce_queue(d->blkq);
231		blk_mq_unquiesce_queue(d->blkq);
232		blk_mq_unfreeze_queue(d->blkq);
233	}
234
235	if (d->gd)
236		set_capacity(d->gd, 0);
237}
238
239/* return whether the user asked for this particular
240 * device to be flushed
241 */
242static int
243user_req(char *s, size_t slen, struct aoedev *d)
244{
245	const char *p;
246	size_t lim;
247
248	if (!d->gd)
249		return 0;
250	p = kbasename(d->gd->disk_name);
251	lim = sizeof(d->gd->disk_name);
252	lim -= p - d->gd->disk_name;
253	if (slen < lim)
254		lim = slen;
255
256	return !strncmp(s, p, lim);
257}
258
259static void
260freedev(struct aoedev *d)
261{
262	struct aoetgt **t, **e;
263	int freeing = 0;
264	unsigned long flags;
265
266	spin_lock_irqsave(&d->lock, flags);
267	if (d->flags & DEVFL_TKILL
268	&& !(d->flags & DEVFL_FREEING)) {
269		d->flags |= DEVFL_FREEING;
270		freeing = 1;
271	}
272	spin_unlock_irqrestore(&d->lock, flags);
273	if (!freeing)
274		return;
275
276	del_timer_sync(&d->timer);
277	if (d->gd) {
278		aoedisk_rm_debugfs(d);
279		del_gendisk(d->gd);
280		put_disk(d->gd);
281		blk_mq_free_tag_set(&d->tag_set);
282	}
283	t = d->targets;
284	e = t + d->ntargets;
285	for (; t < e && *t; t++)
286		freetgt(d, *t);
287
288	mempool_destroy(d->bufpool);
289	skbpoolfree(d);
290	minor_free(d->sysminor);
291
292	spin_lock_irqsave(&d->lock, flags);
293	d->flags |= DEVFL_FREED;
294	spin_unlock_irqrestore(&d->lock, flags);
295}
296
297enum flush_parms {
298	NOT_EXITING = 0,
299	EXITING = 1,
300};
301
302static int
303flush(const char __user *str, size_t cnt, int exiting)
304{
305	ulong flags;
306	struct aoedev *d, **dd;
307	char buf[16];
308	int all = 0;
309	int specified = 0;	/* flush a specific device */
310	unsigned int skipflags;
311
312	skipflags = DEVFL_GDALLOC | DEVFL_NEWSIZE | DEVFL_TKILL;
313
314	if (!exiting && cnt >= 3) {
315		if (cnt > sizeof buf)
316			cnt = sizeof buf;
317		if (copy_from_user(buf, str, cnt))
318			return -EFAULT;
319		all = !strncmp(buf, "all", 3);
320		if (!all)
321			specified = 1;
322	}
323
324	flush_workqueue(aoe_wq);
325	/* pass one: do aoedev_downdev, which might sleep */
326restart1:
327	spin_lock_irqsave(&devlist_lock, flags);
328	for (d = devlist; d; d = d->next) {
329		spin_lock(&d->lock);
330		if (d->flags & DEVFL_TKILL)
331			goto cont;
332
333		if (exiting) {
334			/* unconditionally take each device down */
335		} else if (specified) {
336			if (!user_req(buf, cnt, d))
337				goto cont;
338		} else if ((!all && (d->flags & DEVFL_UP))
339		|| d->flags & skipflags
340		|| d->nopen
341		|| d->ref)
342			goto cont;
343
344		spin_unlock(&d->lock);
345		spin_unlock_irqrestore(&devlist_lock, flags);
346		aoedev_downdev(d);
347		d->flags |= DEVFL_TKILL;
348		goto restart1;
349cont:
350		spin_unlock(&d->lock);
351	}
352	spin_unlock_irqrestore(&devlist_lock, flags);
353
354	/* pass two: call freedev, which might sleep,
355	 * for aoedevs marked with DEVFL_TKILL
356	 */
357restart2:
358	spin_lock_irqsave(&devlist_lock, flags);
359	for (d = devlist; d; d = d->next) {
360		spin_lock(&d->lock);
361		if (d->flags & DEVFL_TKILL
362		&& !(d->flags & DEVFL_FREEING)) {
363			spin_unlock(&d->lock);
364			spin_unlock_irqrestore(&devlist_lock, flags);
365			freedev(d);
366			goto restart2;
367		}
368		spin_unlock(&d->lock);
369	}
370
371	/* pass three: remove aoedevs marked with DEVFL_FREED */
372	for (dd = &devlist, d = *dd; d; d = *dd) {
373		struct aoedev *doomed = NULL;
374
375		spin_lock(&d->lock);
376		if (d->flags & DEVFL_FREED) {
377			*dd = d->next;
378			doomed = d;
379		} else {
380			dd = &d->next;
381		}
382		spin_unlock(&d->lock);
383		if (doomed)
384			kfree(doomed->targets);
385		kfree(doomed);
386	}
387	spin_unlock_irqrestore(&devlist_lock, flags);
388
389	return 0;
390}
391
392int
393aoedev_flush(const char __user *str, size_t cnt)
394{
395	return flush(str, cnt, NOT_EXITING);
396}
397
398/* This has been confirmed to occur once with Tms=3*1000 due to the
399 * driver changing link and not processing its transmit ring.  The
400 * problem is hard enough to solve by returning an error that I'm
401 * still punting on "solving" this.
402 */
403static void
404skbfree(struct sk_buff *skb)
405{
406	enum { Sms = 250, Tms = 30 * 1000};
407	int i = Tms / Sms;
408
409	if (skb == NULL)
410		return;
411	while (atomic_read(&skb_shinfo(skb)->dataref) != 1 && i-- > 0)
412		msleep(Sms);
413	if (i < 0) {
414		printk(KERN_ERR
415			"aoe: %s holds ref: %s\n",
416			skb->dev ? skb->dev->name : "netif",
417			"cannot free skb -- memory leaked.");
418		return;
419	}
420	skb->truesize -= skb->data_len;
421	skb_shinfo(skb)->nr_frags = skb->data_len = 0;
422	skb_trim(skb, 0);
423	dev_kfree_skb(skb);
424}
425
426static void
427skbpoolfree(struct aoedev *d)
428{
429	struct sk_buff *skb, *tmp;
430
431	skb_queue_walk_safe(&d->skbpool, skb, tmp)
432		skbfree(skb);
433
434	__skb_queue_head_init(&d->skbpool);
435}
436
437/* find it or allocate it */
438struct aoedev *
439aoedev_by_aoeaddr(ulong maj, int min, int do_alloc)
440{
441	struct aoedev *d;
442	int i;
443	ulong flags;
444	ulong sysminor = 0;
445
446	spin_lock_irqsave(&devlist_lock, flags);
447
448	for (d=devlist; d; d=d->next)
449		if (d->aoemajor == maj && d->aoeminor == min) {
450			spin_lock(&d->lock);
451			if (d->flags & DEVFL_TKILL) {
452				spin_unlock(&d->lock);
453				d = NULL;
454				goto out;
455			}
456			d->ref++;
457			spin_unlock(&d->lock);
458			break;
459		}
460	if (d || !do_alloc || minor_get(&sysminor, maj, min) < 0)
461		goto out;
462	d = kcalloc(1, sizeof *d, GFP_ATOMIC);
463	if (!d)
464		goto out;
465	d->targets = kcalloc(NTARGETS, sizeof(*d->targets), GFP_ATOMIC);
466	if (!d->targets) {
467		kfree(d);
468		d = NULL;
469		goto out;
470	}
471	d->ntargets = NTARGETS;
472	INIT_WORK(&d->work, aoecmd_sleepwork);
473	spin_lock_init(&d->lock);
474	INIT_LIST_HEAD(&d->rq_list);
475	skb_queue_head_init(&d->skbpool);
476	timer_setup(&d->timer, dummy_timer, 0);
477	d->timer.expires = jiffies + HZ;
478	add_timer(&d->timer);
479	d->bufpool = NULL;	/* defer to aoeblk_gdalloc */
480	d->tgt = d->targets;
481	d->ref = 1;
482	for (i = 0; i < NFACTIVE; i++)
483		INIT_LIST_HEAD(&d->factive[i]);
484	INIT_LIST_HEAD(&d->rexmitq);
485	d->sysminor = sysminor;
486	d->aoemajor = maj;
487	d->aoeminor = min;
488	d->rttavg = RTTAVG_INIT;
489	d->rttdev = RTTDEV_INIT;
490	d->next = devlist;
491	devlist = d;
492 out:
493	spin_unlock_irqrestore(&devlist_lock, flags);
494	return d;
495}
496
497static void
498freetgt(struct aoedev *d, struct aoetgt *t)
499{
500	struct frame *f;
501	struct list_head *pos, *nx, *head;
502	struct aoeif *ifp;
503
504	for (ifp = t->ifs; ifp < &t->ifs[NAOEIFS]; ++ifp) {
505		if (!ifp->nd)
506			break;
507		dev_put(ifp->nd);
508	}
509
510	head = &t->ffree;
511	list_for_each_safe(pos, nx, head) {
512		list_del(pos);
513		f = list_entry(pos, struct frame, head);
514		skbfree(f->skb);
515		kfree(f);
516	}
517	kfree(t);
518}
519
520void
521aoedev_exit(void)
522{
523	flush_workqueue(aoe_wq);
524	flush(NULL, 0, EXITING);
525}
526
527int __init
528aoedev_init(void)
529{
530	return 0;
531}
532