xref: /openbmc/linux/fs/orangefs/orangefs-bufmap.c (revision ba61bb17)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * (C) 2001 Clemson University and The University of Chicago
4  *
5  * See COPYING in top-level directory.
6  */
7 #include "protocol.h"
8 #include "orangefs-kernel.h"
9 #include "orangefs-bufmap.h"
10 
11 struct slot_map {
12 	int c;
13 	wait_queue_head_t q;
14 	int count;
15 	unsigned long *map;
16 };
17 
18 static struct slot_map rw_map = {
19 	.c = -1,
20 	.q = __WAIT_QUEUE_HEAD_INITIALIZER(rw_map.q)
21 };
22 static struct slot_map readdir_map = {
23 	.c = -1,
24 	.q = __WAIT_QUEUE_HEAD_INITIALIZER(readdir_map.q)
25 };
26 
27 
28 static void install(struct slot_map *m, int count, unsigned long *map)
29 {
30 	spin_lock(&m->q.lock);
31 	m->c = m->count = count;
32 	m->map = map;
33 	wake_up_all_locked(&m->q);
34 	spin_unlock(&m->q.lock);
35 }
36 
37 static void mark_killed(struct slot_map *m)
38 {
39 	spin_lock(&m->q.lock);
40 	m->c -= m->count + 1;
41 	spin_unlock(&m->q.lock);
42 }
43 
44 static void run_down(struct slot_map *m)
45 {
46 	DEFINE_WAIT(wait);
47 	spin_lock(&m->q.lock);
48 	if (m->c != -1) {
49 		for (;;) {
50 			if (likely(list_empty(&wait.entry)))
51 				__add_wait_queue_entry_tail(&m->q, &wait);
52 			set_current_state(TASK_UNINTERRUPTIBLE);
53 
54 			if (m->c == -1)
55 				break;
56 
57 			spin_unlock(&m->q.lock);
58 			schedule();
59 			spin_lock(&m->q.lock);
60 		}
61 		__remove_wait_queue(&m->q, &wait);
62 		__set_current_state(TASK_RUNNING);
63 	}
64 	m->map = NULL;
65 	spin_unlock(&m->q.lock);
66 }
67 
68 static void put(struct slot_map *m, int slot)
69 {
70 	int v;
71 	spin_lock(&m->q.lock);
72 	__clear_bit(slot, m->map);
73 	v = ++m->c;
74 	if (v > 0)
75 		wake_up_locked(&m->q);
76 	if (unlikely(v == -1))     /* finished dying */
77 		wake_up_all_locked(&m->q);
78 	spin_unlock(&m->q.lock);
79 }
80 
81 static int wait_for_free(struct slot_map *m)
82 {
83 	long left = slot_timeout_secs * HZ;
84 	DEFINE_WAIT(wait);
85 
86 	do {
87 		long n = left, t;
88 		if (likely(list_empty(&wait.entry)))
89 			__add_wait_queue_entry_tail_exclusive(&m->q, &wait);
90 		set_current_state(TASK_INTERRUPTIBLE);
91 
92 		if (m->c > 0)
93 			break;
94 
95 		if (m->c < 0) {
96 			/* we are waiting for map to be installed */
97 			/* it would better be there soon, or we go away */
98 			if (n > ORANGEFS_BUFMAP_WAIT_TIMEOUT_SECS * HZ)
99 				n = ORANGEFS_BUFMAP_WAIT_TIMEOUT_SECS * HZ;
100 		}
101 		spin_unlock(&m->q.lock);
102 		t = schedule_timeout(n);
103 		spin_lock(&m->q.lock);
104 		if (unlikely(!t) && n != left && m->c < 0)
105 			left = t;
106 		else
107 			left = t + (left - n);
108 		if (unlikely(signal_pending(current)))
109 			left = -EINTR;
110 	} while (left > 0);
111 
112 	if (!list_empty(&wait.entry))
113 		list_del(&wait.entry);
114 	else if (left <= 0 && waitqueue_active(&m->q))
115 		__wake_up_locked_key(&m->q, TASK_INTERRUPTIBLE, NULL);
116 	__set_current_state(TASK_RUNNING);
117 
118 	if (likely(left > 0))
119 		return 0;
120 
121 	return left < 0 ? -EINTR : -ETIMEDOUT;
122 }
123 
124 static int get(struct slot_map *m)
125 {
126 	int res = 0;
127 	spin_lock(&m->q.lock);
128 	if (unlikely(m->c <= 0))
129 		res = wait_for_free(m);
130 	if (likely(!res)) {
131 		m->c--;
132 		res = find_first_zero_bit(m->map, m->count);
133 		__set_bit(res, m->map);
134 	}
135 	spin_unlock(&m->q.lock);
136 	return res;
137 }
138 
139 /* used to describe mapped buffers */
140 struct orangefs_bufmap_desc {
141 	void __user *uaddr;		/* user space address pointer */
142 	struct page **page_array;	/* array of mapped pages */
143 	int array_count;		/* size of above arrays */
144 	struct list_head list_link;
145 };
146 
147 static struct orangefs_bufmap {
148 	int desc_size;
149 	int desc_shift;
150 	int desc_count;
151 	int total_size;
152 	int page_count;
153 
154 	struct page **page_array;
155 	struct orangefs_bufmap_desc *desc_array;
156 
157 	/* array to track usage of buffer descriptors */
158 	unsigned long *buffer_index_array;
159 
160 	/* array to track usage of buffer descriptors for readdir */
161 #define N DIV_ROUND_UP(ORANGEFS_READDIR_DEFAULT_DESC_COUNT, BITS_PER_LONG)
162 	unsigned long readdir_index_array[N];
163 #undef N
164 } *__orangefs_bufmap;
165 
166 static DEFINE_SPINLOCK(orangefs_bufmap_lock);
167 
168 static void
169 orangefs_bufmap_unmap(struct orangefs_bufmap *bufmap)
170 {
171 	int i;
172 
173 	for (i = 0; i < bufmap->page_count; i++)
174 		put_page(bufmap->page_array[i]);
175 }
176 
177 static void
178 orangefs_bufmap_free(struct orangefs_bufmap *bufmap)
179 {
180 	kfree(bufmap->page_array);
181 	kfree(bufmap->desc_array);
182 	kfree(bufmap->buffer_index_array);
183 	kfree(bufmap);
184 }
185 
186 /*
187  * XXX: Can the size and shift change while the caller gives up the
188  * XXX: lock between calling this and doing something useful?
189  */
190 
191 int orangefs_bufmap_size_query(void)
192 {
193 	struct orangefs_bufmap *bufmap;
194 	int size = 0;
195 	spin_lock(&orangefs_bufmap_lock);
196 	bufmap = __orangefs_bufmap;
197 	if (bufmap)
198 		size = bufmap->desc_size;
199 	spin_unlock(&orangefs_bufmap_lock);
200 	return size;
201 }
202 
203 int orangefs_bufmap_shift_query(void)
204 {
205 	struct orangefs_bufmap *bufmap;
206 	int shift = 0;
207 	spin_lock(&orangefs_bufmap_lock);
208 	bufmap = __orangefs_bufmap;
209 	if (bufmap)
210 		shift = bufmap->desc_shift;
211 	spin_unlock(&orangefs_bufmap_lock);
212 	return shift;
213 }
214 
215 static DECLARE_WAIT_QUEUE_HEAD(bufmap_waitq);
216 static DECLARE_WAIT_QUEUE_HEAD(readdir_waitq);
217 
218 static struct orangefs_bufmap *
219 orangefs_bufmap_alloc(struct ORANGEFS_dev_map_desc *user_desc)
220 {
221 	struct orangefs_bufmap *bufmap;
222 
223 	bufmap = kzalloc(sizeof(*bufmap), GFP_KERNEL);
224 	if (!bufmap)
225 		goto out;
226 
227 	bufmap->total_size = user_desc->total_size;
228 	bufmap->desc_count = user_desc->count;
229 	bufmap->desc_size = user_desc->size;
230 	bufmap->desc_shift = ilog2(bufmap->desc_size);
231 
232 	bufmap->buffer_index_array =
233 		kzalloc(DIV_ROUND_UP(bufmap->desc_count, BITS_PER_LONG), GFP_KERNEL);
234 	if (!bufmap->buffer_index_array)
235 		goto out_free_bufmap;
236 
237 	bufmap->desc_array =
238 		kcalloc(bufmap->desc_count, sizeof(struct orangefs_bufmap_desc),
239 			GFP_KERNEL);
240 	if (!bufmap->desc_array)
241 		goto out_free_index_array;
242 
243 	bufmap->page_count = bufmap->total_size / PAGE_SIZE;
244 
245 	/* allocate storage to track our page mappings */
246 	bufmap->page_array =
247 		kcalloc(bufmap->page_count, sizeof(struct page *), GFP_KERNEL);
248 	if (!bufmap->page_array)
249 		goto out_free_desc_array;
250 
251 	return bufmap;
252 
253 out_free_desc_array:
254 	kfree(bufmap->desc_array);
255 out_free_index_array:
256 	kfree(bufmap->buffer_index_array);
257 out_free_bufmap:
258 	kfree(bufmap);
259 out:
260 	return NULL;
261 }
262 
263 static int
264 orangefs_bufmap_map(struct orangefs_bufmap *bufmap,
265 		struct ORANGEFS_dev_map_desc *user_desc)
266 {
267 	int pages_per_desc = bufmap->desc_size / PAGE_SIZE;
268 	int offset = 0, ret, i;
269 
270 	/* map the pages */
271 	ret = get_user_pages_fast((unsigned long)user_desc->ptr,
272 			     bufmap->page_count, 1, bufmap->page_array);
273 
274 	if (ret < 0)
275 		return ret;
276 
277 	if (ret != bufmap->page_count) {
278 		gossip_err("orangefs error: asked for %d pages, only got %d.\n",
279 				bufmap->page_count, ret);
280 
281 		for (i = 0; i < ret; i++) {
282 			SetPageError(bufmap->page_array[i]);
283 			put_page(bufmap->page_array[i]);
284 		}
285 		return -ENOMEM;
286 	}
287 
288 	/*
289 	 * ideally we want to get kernel space pointers for each page, but
290 	 * we can't kmap that many pages at once if highmem is being used.
291 	 * so instead, we just kmap/kunmap the page address each time the
292 	 * kaddr is needed.
293 	 */
294 	for (i = 0; i < bufmap->page_count; i++)
295 		flush_dcache_page(bufmap->page_array[i]);
296 
297 	/* build a list of available descriptors */
298 	for (offset = 0, i = 0; i < bufmap->desc_count; i++) {
299 		bufmap->desc_array[i].page_array = &bufmap->page_array[offset];
300 		bufmap->desc_array[i].array_count = pages_per_desc;
301 		bufmap->desc_array[i].uaddr =
302 		    (user_desc->ptr + (i * pages_per_desc * PAGE_SIZE));
303 		offset += pages_per_desc;
304 	}
305 
306 	return 0;
307 }
308 
309 /*
310  * orangefs_bufmap_initialize()
311  *
312  * initializes the mapped buffer interface
313  *
314  * returns 0 on success, -errno on failure
315  */
316 int orangefs_bufmap_initialize(struct ORANGEFS_dev_map_desc *user_desc)
317 {
318 	struct orangefs_bufmap *bufmap;
319 	int ret = -EINVAL;
320 
321 	gossip_debug(GOSSIP_BUFMAP_DEBUG,
322 		     "orangefs_bufmap_initialize: called (ptr ("
323 		     "%p) sz (%d) cnt(%d).\n",
324 		     user_desc->ptr,
325 		     user_desc->size,
326 		     user_desc->count);
327 
328 	if (user_desc->total_size < 0 ||
329 	    user_desc->size < 0 ||
330 	    user_desc->count < 0)
331 		goto out;
332 
333 	/*
334 	 * sanity check alignment and size of buffer that caller wants to
335 	 * work with
336 	 */
337 	if (PAGE_ALIGN((unsigned long)user_desc->ptr) !=
338 	    (unsigned long)user_desc->ptr) {
339 		gossip_err("orangefs error: memory alignment (front). %p\n",
340 			   user_desc->ptr);
341 		goto out;
342 	}
343 
344 	if (PAGE_ALIGN(((unsigned long)user_desc->ptr + user_desc->total_size))
345 	    != (unsigned long)(user_desc->ptr + user_desc->total_size)) {
346 		gossip_err("orangefs error: memory alignment (back).(%p + %d)\n",
347 			   user_desc->ptr,
348 			   user_desc->total_size);
349 		goto out;
350 	}
351 
352 	if (user_desc->total_size != (user_desc->size * user_desc->count)) {
353 		gossip_err("orangefs error: user provided an oddly sized buffer: (%d, %d, %d)\n",
354 			   user_desc->total_size,
355 			   user_desc->size,
356 			   user_desc->count);
357 		goto out;
358 	}
359 
360 	if ((user_desc->size % PAGE_SIZE) != 0) {
361 		gossip_err("orangefs error: bufmap size not page size divisible (%d).\n",
362 			   user_desc->size);
363 		goto out;
364 	}
365 
366 	ret = -ENOMEM;
367 	bufmap = orangefs_bufmap_alloc(user_desc);
368 	if (!bufmap)
369 		goto out;
370 
371 	ret = orangefs_bufmap_map(bufmap, user_desc);
372 	if (ret)
373 		goto out_free_bufmap;
374 
375 
376 	spin_lock(&orangefs_bufmap_lock);
377 	if (__orangefs_bufmap) {
378 		spin_unlock(&orangefs_bufmap_lock);
379 		gossip_err("orangefs: error: bufmap already initialized.\n");
380 		ret = -EINVAL;
381 		goto out_unmap_bufmap;
382 	}
383 	__orangefs_bufmap = bufmap;
384 	install(&rw_map,
385 		bufmap->desc_count,
386 		bufmap->buffer_index_array);
387 	install(&readdir_map,
388 		ORANGEFS_READDIR_DEFAULT_DESC_COUNT,
389 		bufmap->readdir_index_array);
390 	spin_unlock(&orangefs_bufmap_lock);
391 
392 	gossip_debug(GOSSIP_BUFMAP_DEBUG,
393 		     "orangefs_bufmap_initialize: exiting normally\n");
394 	return 0;
395 
396 out_unmap_bufmap:
397 	orangefs_bufmap_unmap(bufmap);
398 out_free_bufmap:
399 	orangefs_bufmap_free(bufmap);
400 out:
401 	return ret;
402 }
403 
404 /*
405  * orangefs_bufmap_finalize()
406  *
407  * shuts down the mapped buffer interface and releases any resources
408  * associated with it
409  *
410  * no return value
411  */
412 void orangefs_bufmap_finalize(void)
413 {
414 	struct orangefs_bufmap *bufmap = __orangefs_bufmap;
415 	if (!bufmap)
416 		return;
417 	gossip_debug(GOSSIP_BUFMAP_DEBUG, "orangefs_bufmap_finalize: called\n");
418 	mark_killed(&rw_map);
419 	mark_killed(&readdir_map);
420 	gossip_debug(GOSSIP_BUFMAP_DEBUG,
421 		     "orangefs_bufmap_finalize: exiting normally\n");
422 }
423 
424 void orangefs_bufmap_run_down(void)
425 {
426 	struct orangefs_bufmap *bufmap = __orangefs_bufmap;
427 	if (!bufmap)
428 		return;
429 	run_down(&rw_map);
430 	run_down(&readdir_map);
431 	spin_lock(&orangefs_bufmap_lock);
432 	__orangefs_bufmap = NULL;
433 	spin_unlock(&orangefs_bufmap_lock);
434 	orangefs_bufmap_unmap(bufmap);
435 	orangefs_bufmap_free(bufmap);
436 }
437 
438 /*
439  * orangefs_bufmap_get()
440  *
441  * gets a free mapped buffer descriptor, will sleep until one becomes
442  * available if necessary
443  *
444  * returns slot on success, -errno on failure
445  */
446 int orangefs_bufmap_get(void)
447 {
448 	return get(&rw_map);
449 }
450 
451 /*
452  * orangefs_bufmap_put()
453  *
454  * returns a mapped buffer descriptor to the collection
455  *
456  * no return value
457  */
458 void orangefs_bufmap_put(int buffer_index)
459 {
460 	put(&rw_map, buffer_index);
461 }
462 
463 /*
464  * orangefs_readdir_index_get()
465  *
466  * gets a free descriptor, will sleep until one becomes
467  * available if necessary.
468  * Although the readdir buffers are not mapped into kernel space
469  * we could do that at a later point of time. Regardless, these
470  * indices are used by the client-core.
471  *
472  * returns slot on success, -errno on failure
473  */
474 int orangefs_readdir_index_get(void)
475 {
476 	return get(&readdir_map);
477 }
478 
479 void orangefs_readdir_index_put(int buffer_index)
480 {
481 	put(&readdir_map, buffer_index);
482 }
483 
484 /*
485  * we've been handed an iovec, we need to copy it to
486  * the shared memory descriptor at "buffer_index".
487  */
488 int orangefs_bufmap_copy_from_iovec(struct iov_iter *iter,
489 				int buffer_index,
490 				size_t size)
491 {
492 	struct orangefs_bufmap_desc *to;
493 	int i;
494 
495 	gossip_debug(GOSSIP_BUFMAP_DEBUG,
496 		     "%s: buffer_index:%d: size:%zu:\n",
497 		     __func__, buffer_index, size);
498 
499 	to = &__orangefs_bufmap->desc_array[buffer_index];
500 	for (i = 0; size; i++) {
501 		struct page *page = to->page_array[i];
502 		size_t n = size;
503 		if (n > PAGE_SIZE)
504 			n = PAGE_SIZE;
505 		if (copy_page_from_iter(page, 0, n, iter) != n)
506 			return -EFAULT;
507 		size -= n;
508 	}
509 	return 0;
510 }
511 
512 /*
513  * we've been handed an iovec, we need to fill it from
514  * the shared memory descriptor at "buffer_index".
515  */
516 int orangefs_bufmap_copy_to_iovec(struct iov_iter *iter,
517 				    int buffer_index,
518 				    size_t size)
519 {
520 	struct orangefs_bufmap_desc *from;
521 	int i;
522 
523 	from = &__orangefs_bufmap->desc_array[buffer_index];
524 	gossip_debug(GOSSIP_BUFMAP_DEBUG,
525 		     "%s: buffer_index:%d: size:%zu:\n",
526 		     __func__, buffer_index, size);
527 
528 
529 	for (i = 0; size; i++) {
530 		struct page *page = from->page_array[i];
531 		size_t n = size;
532 		if (n > PAGE_SIZE)
533 			n = PAGE_SIZE;
534 		n = copy_page_to_iter(page, 0, n, iter);
535 		if (!n)
536 			return -EFAULT;
537 		size -= n;
538 	}
539 	return 0;
540 }
541