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11#include "qemu/osdep.h"
12#include <liburing.h>
13#include "qemu-common.h"
14#include "block/aio.h"
15#include "qemu/queue.h"
16#include "block/block.h"
17#include "block/raw-aio.h"
18#include "qemu/coroutine.h"
19#include "qapi/error.h"
20#include "trace.h"
21
22
23#define MAX_ENTRIES 128
24
25typedef struct LuringAIOCB {
26 Coroutine *co;
27 struct io_uring_sqe sqeq;
28 ssize_t ret;
29 QEMUIOVector *qiov;
30 bool is_read;
31 QSIMPLEQ_ENTRY(LuringAIOCB) next;
32
33
34
35
36
37 int total_read;
38 QEMUIOVector resubmit_qiov;
39} LuringAIOCB;
40
41typedef struct LuringQueue {
42 int plugged;
43 unsigned int in_queue;
44 unsigned int in_flight;
45 bool blocked;
46 QSIMPLEQ_HEAD(, LuringAIOCB) submit_queue;
47} LuringQueue;
48
49typedef struct LuringState {
50 AioContext *aio_context;
51
52 struct io_uring ring;
53
54
55 LuringQueue io_q;
56
57
58 QEMUBH *completion_bh;
59} LuringState;
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66
67static void luring_resubmit(LuringState *s, LuringAIOCB *luringcb)
68{
69 QSIMPLEQ_INSERT_TAIL(&s->io_q.submit_queue, luringcb, next);
70 s->io_q.in_queue++;
71}
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82
83static void luring_resubmit_short_read(LuringState *s, LuringAIOCB *luringcb,
84 int nread)
85{
86 QEMUIOVector *resubmit_qiov;
87 size_t remaining;
88
89 trace_luring_resubmit_short_read(s, luringcb, nread);
90
91
92 luringcb->total_read = nread;
93 remaining = luringcb->qiov->size - luringcb->total_read;
94
95
96 resubmit_qiov = &luringcb->resubmit_qiov;
97 if (resubmit_qiov->iov == NULL) {
98 qemu_iovec_init(resubmit_qiov, luringcb->qiov->niov);
99 } else {
100 qemu_iovec_reset(resubmit_qiov);
101 }
102 qemu_iovec_concat(resubmit_qiov, luringcb->qiov, luringcb->total_read,
103 remaining);
104
105
106 luringcb->sqeq.off = nread;
107 luringcb->sqeq.addr = (__u64)(uintptr_t)luringcb->resubmit_qiov.iov;
108 luringcb->sqeq.len = luringcb->resubmit_qiov.niov;
109
110 luring_resubmit(s, luringcb);
111}
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125
126static void luring_process_completions(LuringState *s)
127{
128 struct io_uring_cqe *cqes;
129 int total_bytes;
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145 qemu_bh_schedule(s->completion_bh);
146
147 while (io_uring_peek_cqe(&s->ring, &cqes) == 0) {
148 LuringAIOCB *luringcb;
149 int ret;
150
151 if (!cqes) {
152 break;
153 }
154
155 luringcb = io_uring_cqe_get_data(cqes);
156 ret = cqes->res;
157 io_uring_cqe_seen(&s->ring, cqes);
158 cqes = NULL;
159
160
161 s->io_q.in_flight--;
162 trace_luring_process_completion(s, luringcb, ret);
163
164
165 total_bytes = ret + luringcb->total_read;
166
167 if (ret < 0) {
168 if (ret == -EINTR) {
169 luring_resubmit(s, luringcb);
170 continue;
171 }
172 } else if (!luringcb->qiov) {
173 goto end;
174 } else if (total_bytes == luringcb->qiov->size) {
175 ret = 0;
176
177 } else {
178
179 if (luringcb->is_read) {
180 if (ret > 0) {
181 luring_resubmit_short_read(s, luringcb, ret);
182 continue;
183 } else {
184
185 qemu_iovec_memset(luringcb->qiov, total_bytes, 0,
186 luringcb->qiov->size - total_bytes);
187 ret = 0;
188 }
189 } else {
190 ret = -ENOSPC;
191 }
192 }
193end:
194 luringcb->ret = ret;
195 qemu_iovec_destroy(&luringcb->resubmit_qiov);
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203 if (!qemu_coroutine_entered(luringcb->co)) {
204 aio_co_wake(luringcb->co);
205 }
206 }
207 qemu_bh_cancel(s->completion_bh);
208}
209
210static int ioq_submit(LuringState *s)
211{
212 int ret = 0;
213 LuringAIOCB *luringcb, *luringcb_next;
214
215 while (s->io_q.in_queue > 0) {
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220 QSIMPLEQ_FOREACH_SAFE(luringcb, &s->io_q.submit_queue, next,
221 luringcb_next) {
222 struct io_uring_sqe *sqes = io_uring_get_sqe(&s->ring);
223 if (!sqes) {
224 break;
225 }
226
227 *sqes = luringcb->sqeq;
228 QSIMPLEQ_REMOVE_HEAD(&s->io_q.submit_queue, next);
229 }
230 ret = io_uring_submit(&s->ring);
231 trace_luring_io_uring_submit(s, ret);
232
233 if (ret <= 0) {
234 if (ret == -EAGAIN || ret == -EINTR) {
235 continue;
236 }
237 break;
238 }
239 s->io_q.in_flight += ret;
240 s->io_q.in_queue -= ret;
241 }
242 s->io_q.blocked = (s->io_q.in_queue > 0);
243
244 if (s->io_q.in_flight) {
245
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249 luring_process_completions(s);
250 }
251 return ret;
252}
253
254static void luring_process_completions_and_submit(LuringState *s)
255{
256 aio_context_acquire(s->aio_context);
257 luring_process_completions(s);
258
259 if (!s->io_q.plugged && s->io_q.in_queue > 0) {
260 ioq_submit(s);
261 }
262 aio_context_release(s->aio_context);
263}
264
265static void qemu_luring_completion_bh(void *opaque)
266{
267 LuringState *s = opaque;
268 luring_process_completions_and_submit(s);
269}
270
271static void qemu_luring_completion_cb(void *opaque)
272{
273 LuringState *s = opaque;
274 luring_process_completions_and_submit(s);
275}
276
277static bool qemu_luring_poll_cb(void *opaque)
278{
279 LuringState *s = opaque;
280
281 if (io_uring_cq_ready(&s->ring)) {
282 luring_process_completions_and_submit(s);
283 return true;
284 }
285
286 return false;
287}
288
289static void ioq_init(LuringQueue *io_q)
290{
291 QSIMPLEQ_INIT(&io_q->submit_queue);
292 io_q->plugged = 0;
293 io_q->in_queue = 0;
294 io_q->in_flight = 0;
295 io_q->blocked = false;
296}
297
298void luring_io_plug(BlockDriverState *bs, LuringState *s)
299{
300 trace_luring_io_plug(s);
301 s->io_q.plugged++;
302}
303
304void luring_io_unplug(BlockDriverState *bs, LuringState *s)
305{
306 assert(s->io_q.plugged);
307 trace_luring_io_unplug(s, s->io_q.blocked, s->io_q.plugged,
308 s->io_q.in_queue, s->io_q.in_flight);
309 if (--s->io_q.plugged == 0 &&
310 !s->io_q.blocked && s->io_q.in_queue > 0) {
311 ioq_submit(s);
312 }
313}
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326static int luring_do_submit(int fd, LuringAIOCB *luringcb, LuringState *s,
327 uint64_t offset, int type)
328{
329 int ret;
330 struct io_uring_sqe *sqes = &luringcb->sqeq;
331
332 switch (type) {
333 case QEMU_AIO_WRITE:
334 io_uring_prep_writev(sqes, fd, luringcb->qiov->iov,
335 luringcb->qiov->niov, offset);
336 break;
337 case QEMU_AIO_READ:
338 io_uring_prep_readv(sqes, fd, luringcb->qiov->iov,
339 luringcb->qiov->niov, offset);
340 break;
341 case QEMU_AIO_FLUSH:
342 io_uring_prep_fsync(sqes, fd, IORING_FSYNC_DATASYNC);
343 break;
344 default:
345 fprintf(stderr, "%s: invalid AIO request type, aborting 0x%x.\n",
346 __func__, type);
347 abort();
348 }
349 io_uring_sqe_set_data(sqes, luringcb);
350
351 QSIMPLEQ_INSERT_TAIL(&s->io_q.submit_queue, luringcb, next);
352 s->io_q.in_queue++;
353 trace_luring_do_submit(s, s->io_q.blocked, s->io_q.plugged,
354 s->io_q.in_queue, s->io_q.in_flight);
355 if (!s->io_q.blocked &&
356 (!s->io_q.plugged ||
357 s->io_q.in_flight + s->io_q.in_queue >= MAX_ENTRIES)) {
358 ret = ioq_submit(s);
359 trace_luring_do_submit_done(s, ret);
360 return ret;
361 }
362 return 0;
363}
364
365int coroutine_fn luring_co_submit(BlockDriverState *bs, LuringState *s, int fd,
366 uint64_t offset, QEMUIOVector *qiov, int type)
367{
368 int ret;
369 LuringAIOCB luringcb = {
370 .co = qemu_coroutine_self(),
371 .ret = -EINPROGRESS,
372 .qiov = qiov,
373 .is_read = (type == QEMU_AIO_READ),
374 };
375 trace_luring_co_submit(bs, s, &luringcb, fd, offset, qiov ? qiov->size : 0,
376 type);
377 ret = luring_do_submit(fd, &luringcb, s, offset, type);
378
379 if (ret < 0) {
380 return ret;
381 }
382
383 if (luringcb.ret == -EINPROGRESS) {
384 qemu_coroutine_yield();
385 }
386 return luringcb.ret;
387}
388
389void luring_detach_aio_context(LuringState *s, AioContext *old_context)
390{
391 aio_set_fd_handler(old_context, s->ring.ring_fd, false, NULL, NULL, NULL,
392 s);
393 qemu_bh_delete(s->completion_bh);
394 s->aio_context = NULL;
395}
396
397void luring_attach_aio_context(LuringState *s, AioContext *new_context)
398{
399 s->aio_context = new_context;
400 s->completion_bh = aio_bh_new(new_context, qemu_luring_completion_bh, s);
401 aio_set_fd_handler(s->aio_context, s->ring.ring_fd, false,
402 qemu_luring_completion_cb, NULL, qemu_luring_poll_cb, s);
403}
404
405LuringState *luring_init(Error **errp)
406{
407 int rc;
408 LuringState *s = g_new0(LuringState, 1);
409 struct io_uring *ring = &s->ring;
410
411 trace_luring_init_state(s, sizeof(*s));
412
413 rc = io_uring_queue_init(MAX_ENTRIES, ring, 0);
414 if (rc < 0) {
415 error_setg_errno(errp, errno, "failed to init linux io_uring ring");
416 g_free(s);
417 return NULL;
418 }
419
420 ioq_init(&s->io_q);
421 return s;
422
423}
424
425void luring_cleanup(LuringState *s)
426{
427 io_uring_queue_exit(&s->ring);
428 trace_luring_cleanup_state(s);
429 g_free(s);
430}
431