[mirror_qemu.git] / block / io_uring.c

/*
 * Linux io_uring support.
 *
 * Copyright (C) 2009 IBM, Corp.
 * Copyright (C) 2009 Red Hat, Inc.
 * Copyright (C) 2019 Aarushi Mehta
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 */
#include "qemu/osdep.h"
#include <liburing.h>
#include "block/aio.h"
#include "qemu/queue.h"
#include "block/block.h"
#include "block/raw-aio.h"
#include "qemu/coroutine.h"
#include "qapi/error.h"
#include "sysemu/block-backend.h"
#include "trace.h"

/* Only used for assertions.  */
#include "qemu/coroutine_int.h"

/* io_uring ring size */
#define MAX_ENTRIES 128

typedef struct LuringAIOCB {
    Coroutine *co;
    struct io_uring_sqe sqeq;
    ssize_t ret;
    QEMUIOVector *qiov;
    bool is_read;
    QSIMPLEQ_ENTRY(LuringAIOCB) next;

    /*
     * Buffered reads may require resubmission, see
     * luring_resubmit_short_read().
     */
    int total_read;
    QEMUIOVector resubmit_qiov;
} LuringAIOCB;

typedef struct LuringQueue {
    unsigned int in_queue;
    unsigned int in_flight;
    bool blocked;
    QSIMPLEQ_HEAD(, LuringAIOCB) submit_queue;
} LuringQueue;

typedef struct LuringState {
    AioContext *aio_context;

    struct io_uring ring;

    /* No locking required, only accessed from AioContext home thread */
    LuringQueue io_q;

    QEMUBH *completion_bh;
} LuringState;

/**
 * luring_resubmit:
 *
 * Resubmit a request by appending it to submit_queue.  The caller must ensure
 * that ioq_submit() is called later so that submit_queue requests are started.
 */
static void luring_resubmit(LuringState *s, LuringAIOCB *luringcb)
{
    QSIMPLEQ_INSERT_TAIL(&s->io_q.submit_queue, luringcb, next);
    s->io_q.in_queue++;
}

/**
 * luring_resubmit_short_read:
 *
 * Short reads are rare but may occur. The remaining read request needs to be
 * resubmitted.
 */
static void luring_resubmit_short_read(LuringState *s, LuringAIOCB *luringcb,
                                       int nread)
{
    QEMUIOVector *resubmit_qiov;
    size_t remaining;

    trace_luring_resubmit_short_read(s, luringcb, nread);

    /* Update read position */
    luringcb->total_read += nread;
    remaining = luringcb->qiov->size - luringcb->total_read;

    /* Shorten qiov */
    resubmit_qiov = &luringcb->resubmit_qiov;
    if (resubmit_qiov->iov == NULL) {
        qemu_iovec_init(resubmit_qiov, luringcb->qiov->niov);
    } else {
        qemu_iovec_reset(resubmit_qiov);
    }
    qemu_iovec_concat(resubmit_qiov, luringcb->qiov, luringcb->total_read,
                      remaining);

    /* Update sqe */
    luringcb->sqeq.off += nread;
    luringcb->sqeq.addr = (__u64)(uintptr_t)luringcb->resubmit_qiov.iov;
    luringcb->sqeq.len = luringcb->resubmit_qiov.niov;

    luring_resubmit(s, luringcb);
}

/**
 * luring_process_completions:
 * @s: AIO state
 *
 * Fetches completed I/O requests, consumes cqes and invokes their callbacks
 * The function is somewhat tricky because it supports nested event loops, for
 * example when a request callback invokes aio_poll().
 *
 * Function schedules BH completion so it  can be called again in a nested
 * event loop.  When there are no events left  to complete the BH is being
 * canceled.
 *
 */
static void luring_process_completions(LuringState *s)
{
    struct io_uring_cqe *cqes;
    int total_bytes;
    /*
     * Request completion callbacks can run the nested event loop.
     * Schedule ourselves so the nested event loop will "see" remaining
     * completed requests and process them.  Without this, completion
     * callbacks that wait for other requests using a nested event loop
     * would hang forever.
     *
     * This workaround is needed because io_uring uses poll_wait, which
     * is woken up when new events are added to the uring, thus polling on
     * the same uring fd will block unless more events are received.
     *
     * Other leaf block drivers (drivers that access the data themselves)
     * are networking based, so they poll sockets for data and run the
     * correct coroutine.
     */
    qemu_bh_schedule(s->completion_bh);

    while (io_uring_peek_cqe(&s->ring, &cqes) == 0) {
        LuringAIOCB *luringcb;
        int ret;

        if (!cqes) {
            break;
        }

        luringcb = io_uring_cqe_get_data(cqes);
        ret = cqes->res;
        io_uring_cqe_seen(&s->ring, cqes);
        cqes = NULL;

        /* Change counters one-by-one because we can be nested. */
        s->io_q.in_flight--;
        trace_luring_process_completion(s, luringcb, ret);

        /* total_read is non-zero only for resubmitted read requests */
        total_bytes = ret + luringcb->total_read;

        if (ret < 0) {
            /*
             * Only writev/readv/fsync requests on regular files or host block
             * devices are submitted. Therefore -EAGAIN is not expected but it's
             * known to happen sometimes with Linux SCSI. Submit again and hope
             * the request completes successfully.
             *
             * For more information, see:
             * https://lore.kernel.org/io-uring/20210727165811.284510-3-axboe@kernel.dk/T/#u
             *
             * If the code is changed to submit other types of requests in the
             * future, then this workaround may need to be extended to deal with
             * genuine -EAGAIN results that should not be resubmitted
             * immediately.
             */
            if (ret == -EINTR || ret == -EAGAIN) {
                luring_resubmit(s, luringcb);
                continue;
            }
        } else if (!luringcb->qiov) {
            goto end;
        } else if (total_bytes == luringcb->qiov->size) {
            ret = 0;
        /* Only read/write */
        } else {
            /* Short Read/Write */
            if (luringcb->is_read) {
                if (ret > 0) {
                    luring_resubmit_short_read(s, luringcb, ret);
                    continue;
                } else {
                    /* Pad with zeroes */
                    qemu_iovec_memset(luringcb->qiov, total_bytes, 0,
                                      luringcb->qiov->size - total_bytes);
                    ret = 0;
                }
            } else {
                ret = -ENOSPC;
            }
        }
end:
        luringcb->ret = ret;
        qemu_iovec_destroy(&luringcb->resubmit_qiov);

        /*
         * If the coroutine is already entered it must be in ioq_submit()
         * and will notice luringcb->ret has been filled in when it
         * eventually runs later. Coroutines cannot be entered recursively
         * so avoid doing that!
         */
        assert(luringcb->co->ctx == s->aio_context);
        if (!qemu_coroutine_entered(luringcb->co)) {
            aio_co_wake(luringcb->co);
        }
    }
    qemu_bh_cancel(s->completion_bh);
}

static int ioq_submit(LuringState *s)
{
    int ret = 0;
    LuringAIOCB *luringcb, *luringcb_next;

    while (s->io_q.in_queue > 0) {
        /*
         * Try to fetch sqes from the ring for requests waiting in
         * the overflow queue
         */
        QSIMPLEQ_FOREACH_SAFE(luringcb, &s->io_q.submit_queue, next,
                              luringcb_next) {
            struct io_uring_sqe *sqes = io_uring_get_sqe(&s->ring);
            if (!sqes) {
                break;
            }
            /* Prep sqe for submission */
            *sqes = luringcb->sqeq;
            QSIMPLEQ_REMOVE_HEAD(&s->io_q.submit_queue, next);
        }
        ret = io_uring_submit(&s->ring);
        trace_luring_io_uring_submit(s, ret);
        /* Prevent infinite loop if submission is refused */
        if (ret <= 0) {
            if (ret == -EAGAIN || ret == -EINTR) {
                continue;
            }
            break;
        }
        s->io_q.in_flight += ret;
        s->io_q.in_queue  -= ret;
    }
    s->io_q.blocked = (s->io_q.in_queue > 0);

    if (s->io_q.in_flight) {
        /*
         * We can try to complete something just right away if there are
         * still requests in-flight.
         */
        luring_process_completions(s);
    }
    return ret;
}

static void luring_process_completions_and_submit(LuringState *s)
{
    luring_process_completions(s);

    if (s->io_q.in_queue > 0) {
        ioq_submit(s);
    }
}

static void qemu_luring_completion_bh(void *opaque)
{
    LuringState *s = opaque;
    luring_process_completions_and_submit(s);
}

static void qemu_luring_completion_cb(void *opaque)
{
    LuringState *s = opaque;
    luring_process_completions_and_submit(s);
}

static bool qemu_luring_poll_cb(void *opaque)
{
    LuringState *s = opaque;

    return io_uring_cq_ready(&s->ring);
}

static void qemu_luring_poll_ready(void *opaque)
{
    LuringState *s = opaque;

    luring_process_completions_and_submit(s);
}

static void ioq_init(LuringQueue *io_q)
{
    QSIMPLEQ_INIT(&io_q->submit_queue);
    io_q->in_queue = 0;
    io_q->in_flight = 0;
    io_q->blocked = false;
}

static void luring_unplug_fn(void *opaque)
{
    LuringState *s = opaque;
    trace_luring_unplug_fn(s, s->io_q.blocked, s->io_q.in_queue,
                           s->io_q.in_flight);
    if (!s->io_q.blocked && s->io_q.in_queue > 0) {
        ioq_submit(s);
    }
}

/**
 * luring_do_submit:
 * @fd: file descriptor for I/O
 * @luringcb: AIO control block
 * @s: AIO state
 * @offset: offset for request
 * @type: type of request
 *
 * Fetches sqes from ring, adds to pending queue and preps them
 *
 */
static int luring_do_submit(int fd, LuringAIOCB *luringcb, LuringState *s,
                            uint64_t offset, int type)
{
    int ret;
    struct io_uring_sqe *sqes = &luringcb->sqeq;

    switch (type) {
    case QEMU_AIO_WRITE:
        io_uring_prep_writev(sqes, fd, luringcb->qiov->iov,
                             luringcb->qiov->niov, offset);
        break;
    case QEMU_AIO_ZONE_APPEND:
        io_uring_prep_writev(sqes, fd, luringcb->qiov->iov,
                             luringcb->qiov->niov, offset);
        break;
    case QEMU_AIO_READ:
        io_uring_prep_readv(sqes, fd, luringcb->qiov->iov,
                            luringcb->qiov->niov, offset);
        break;
    case QEMU_AIO_FLUSH:
        io_uring_prep_fsync(sqes, fd, IORING_FSYNC_DATASYNC);
        break;
    default:
        fprintf(stderr, "%s: invalid AIO request type, aborting 0x%x.\n",
                        __func__, type);
        abort();
    }
    io_uring_sqe_set_data(sqes, luringcb);

    QSIMPLEQ_INSERT_TAIL(&s->io_q.submit_queue, luringcb, next);
    s->io_q.in_queue++;
    trace_luring_do_submit(s, s->io_q.blocked, s->io_q.in_queue,
                           s->io_q.in_flight);
    if (!s->io_q.blocked) {
        if (s->io_q.in_flight + s->io_q.in_queue >= MAX_ENTRIES) {
            ret = ioq_submit(s);
            trace_luring_do_submit_done(s, ret);
            return ret;
        }

        blk_io_plug_call(luring_unplug_fn, s);
    }
    return 0;
}

int coroutine_fn luring_co_submit(BlockDriverState *bs, int fd, uint64_t offset,
                                  QEMUIOVector *qiov, int type)
{
    int ret;
    AioContext *ctx = qemu_get_current_aio_context();
    LuringState *s = aio_get_linux_io_uring(ctx);
    LuringAIOCB luringcb = {
        .co         = qemu_coroutine_self(),
        .ret        = -EINPROGRESS,
        .qiov       = qiov,
        .is_read    = (type == QEMU_AIO_READ),
    };
    trace_luring_co_submit(bs, s, &luringcb, fd, offset, qiov ? qiov->size : 0,
                           type);
    ret = luring_do_submit(fd, &luringcb, s, offset, type);

    if (ret < 0) {
        return ret;
    }

    if (luringcb.ret == -EINPROGRESS) {
        qemu_coroutine_yield();
    }
    return luringcb.ret;
}

void luring_detach_aio_context(LuringState *s, AioContext *old_context)
{
    aio_set_fd_handler(old_context, s->ring.ring_fd,
                       NULL, NULL, NULL, NULL, s);
    qemu_bh_delete(s->completion_bh);
    s->aio_context = NULL;
}

void luring_attach_aio_context(LuringState *s, AioContext *new_context)
{
    s->aio_context = new_context;
    s->completion_bh = aio_bh_new(new_context, qemu_luring_completion_bh, s);
    aio_set_fd_handler(s->aio_context, s->ring.ring_fd,
                       qemu_luring_completion_cb, NULL,
                       qemu_luring_poll_cb, qemu_luring_poll_ready, s);
}

LuringState *luring_init(Error **errp)
{
    int rc;
    LuringState *s = g_new0(LuringState, 1);
    struct io_uring *ring = &s->ring;

    trace_luring_init_state(s, sizeof(*s));

    rc = io_uring_queue_init(MAX_ENTRIES, ring, 0);
    if (rc < 0) {
        error_setg_errno(errp, errno, "failed to init linux io_uring ring");
        g_free(s);
        return NULL;
    }

    ioq_init(&s->io_q);
    return s;

}

void luring_cleanup(LuringState *s)
{
    io_uring_queue_exit(&s->ring);
    trace_luring_cleanup_state(s);
    g_free(s);
}
Commit	Line	Data
6663a0a3 AM	1	/*
	2	* Linux io_uring support.
	3	*
	4	* Copyright (C) 2009 IBM, Corp.
	5	* Copyright (C) 2009 Red Hat, Inc.
	6	* Copyright (C) 2019 Aarushi Mehta
	7	*
	8	* This work is licensed under the terms of the GNU GPL, version 2 or later.
	9	* See the COPYING file in the top-level directory.
	10	*/
	11	#include "qemu/osdep.h"
	12	#include <liburing.h>
6663a0a3 AM	13	#include "block/aio.h"
	14	#include "qemu/queue.h"
	15	#include "block/block.h"
	16	#include "block/raw-aio.h"
	17	#include "qemu/coroutine.h"
	18	#include "qapi/error.h"
6a6da231	19	#include "sysemu/block-backend.h"
d803f590	20	#include "trace.h"
6663a0a3	21
a75e4e43 EGE	22	/* Only used for assertions. */
	23	#include "qemu/coroutine_int.h"
	24
6663a0a3 AM	25	/* io_uring ring size */
	26	#define MAX_ENTRIES 128
	27
	28	typedef struct LuringAIOCB {
	29	Coroutine *co;
	30	struct io_uring_sqe sqeq;
	31	ssize_t ret;
	32	QEMUIOVector *qiov;
	33	bool is_read;
	34	QSIMPLEQ_ENTRY(LuringAIOCB) next;
	35
	36	/*
	37	* Buffered reads may require resubmission, see
	38	* luring_resubmit_short_read().
	39	*/
	40	int total_read;
	41	QEMUIOVector resubmit_qiov;
	42	} LuringAIOCB;
	43
	44	typedef struct LuringQueue {
6663a0a3 AM	45	unsigned int in_queue;
	46	unsigned int in_flight;
	47	bool blocked;
	48	QSIMPLEQ_HEAD(, LuringAIOCB) submit_queue;
	49	} LuringQueue;
	50
	51	typedef struct LuringState {
	52	AioContext *aio_context;
	53
	54	struct io_uring ring;
	55
a75e4e43	56	/* No locking required, only accessed from AioContext home thread */
6663a0a3 AM	57	LuringQueue io_q;
6663a0a3 AM	58
6663a0a3 AM	59	QEMUBH *completion_bh;
	60	} LuringState;
	61
	62	/**
	63	* luring_resubmit:
	64	*
	65	* Resubmit a request by appending it to submit_queue. The caller must ensure
	66	* that ioq_submit() is called later so that submit_queue requests are started.
	67	*/
	68	static void luring_resubmit(LuringState s, LuringAIOCB luringcb)
	69	{
	70	QSIMPLEQ_INSERT_TAIL(&s->io_q.submit_queue, luringcb, next);
	71	s->io_q.in_queue++;
	72	}
	73
	74	/**
	75	* luring_resubmit_short_read:
	76	*
be6a166f SH	77	* Short reads are rare but may occur. The remaining read request needs to be
be6a166f SH	78	* resubmitted.
6663a0a3 AM	79	*/
	80	static void luring_resubmit_short_read(LuringState s, LuringAIOCB luringcb,
	81	int nread)
	82	{
	83	QEMUIOVector *resubmit_qiov;
	84	size_t remaining;
	85
d803f590 AM	86	trace_luring_resubmit_short_read(s, luringcb, nread);
d803f590 AM	87
6663a0a3	88	/* Update read position */
c06fc7ce	89	luringcb->total_read += nread;
6663a0a3 AM	90	remaining = luringcb->qiov->size - luringcb->total_read;
	91
	92	/* Shorten qiov */
	93	resubmit_qiov = &luringcb->resubmit_qiov;
	94	if (resubmit_qiov->iov == NULL) {
	95	qemu_iovec_init(resubmit_qiov, luringcb->qiov->niov);
	96	} else {
	97	qemu_iovec_reset(resubmit_qiov);
	98	}
	99	qemu_iovec_concat(resubmit_qiov, luringcb->qiov, luringcb->total_read,
	100	remaining);
	101
	102	/* Update sqe */
c06fc7ce	103	luringcb->sqeq.off += nread;
6663a0a3 AM	104	luringcb->sqeq.addr = (__u64)(uintptr_t)luringcb->resubmit_qiov.iov;
	105	luringcb->sqeq.len = luringcb->resubmit_qiov.niov;
	106
	107	luring_resubmit(s, luringcb);
	108	}
	109
	110	/**
	111	* luring_process_completions:
	112	* @s: AIO state
	113	*
	114	* Fetches completed I/O requests, consumes cqes and invokes their callbacks
	115	* The function is somewhat tricky because it supports nested event loops, for
	116	* example when a request callback invokes aio_poll().
	117	*
	118	* Function schedules BH completion so it can be called again in a nested
	119	* event loop. When there are no events left to complete the BH is being
	120	* canceled.
	121	*
	122	*/
	123	static void luring_process_completions(LuringState *s)
	124	{
	125	struct io_uring_cqe *cqes;
	126	int total_bytes;
	127	/*
	128	* Request completion callbacks can run the nested event loop.
	129	* Schedule ourselves so the nested event loop will "see" remaining
	130	* completed requests and process them. Without this, completion
	131	* callbacks that wait for other requests using a nested event loop
	132	* would hang forever.
	133	*
	134	* This workaround is needed because io_uring uses poll_wait, which
	135	* is woken up when new events are added to the uring, thus polling on
	136	* the same uring fd will block unless more events are received.
	137	*
	138	* Other leaf block drivers (drivers that access the data themselves)
	139	* are networking based, so they poll sockets for data and run the
	140	* correct coroutine.
	141	*/
	142	qemu_bh_schedule(s->completion_bh);
	143
	144	while (io_uring_peek_cqe(&s->ring, &cqes) == 0) {
	145	LuringAIOCB *luringcb;
	146	int ret;
	147
	148	if (!cqes) {
	149	break;
	150	}
	151
	152	luringcb = io_uring_cqe_get_data(cqes);
	153	ret = cqes->res;
	154	io_uring_cqe_seen(&s->ring, cqes);
	155	cqes = NULL;
	156
	157	/* Change counters one-by-one because we can be nested. */
	158	s->io_q.in_flight--;
d803f590	159	trace_luring_process_completion(s, luringcb, ret);
6663a0a3 AM	160
	161	/* total_read is non-zero only for resubmitted read requests */
	162	total_bytes = ret + luringcb->total_read;
	163
	164	if (ret < 0) {
54caccb3 FE	165	/*
	166	* Only writev/readv/fsync requests on regular files or host block
	167	* devices are submitted. Therefore -EAGAIN is not expected but it's
	168	* known to happen sometimes with Linux SCSI. Submit again and hope
	169	* the request completes successfully.
	170	*
	171	* For more information, see:
	172	* https://lore.kernel.org/io-uring/20210727165811.284510-3-axboe@kernel.dk/T/#u
	173	*
	174	* If the code is changed to submit other types of requests in the
	175	* future, then this workaround may need to be extended to deal with
	176	* genuine -EAGAIN results that should not be resubmitted
	177	* immediately.
	178	*/
	179	if (ret == -EINTR \|\| ret == -EAGAIN) {
6663a0a3 AM	180	luring_resubmit(s, luringcb);
	181	continue;
	182	}
	183	} else if (!luringcb->qiov) {
	184	goto end;
	185	} else if (total_bytes == luringcb->qiov->size) {
	186	ret = 0;
	187	/* Only read/write */
	188	} else {
	189	/* Short Read/Write */
	190	if (luringcb->is_read) {
	191	if (ret > 0) {
	192	luring_resubmit_short_read(s, luringcb, ret);
	193	continue;
	194	} else {
	195	/* Pad with zeroes */
	196	qemu_iovec_memset(luringcb->qiov, total_bytes, 0,
	197	luringcb->qiov->size - total_bytes);
	198	ret = 0;
	199	}
	200	} else {
74e4a8a9	201	ret = -ENOSPC;
6663a0a3 AM	202	}
	203	}
	204	end:
	205	luringcb->ret = ret;
	206	qemu_iovec_destroy(&luringcb->resubmit_qiov);
	207
	208	/*
	209	* If the coroutine is already entered it must be in ioq_submit()
	210	* and will notice luringcb->ret has been filled in when it
	211	* eventually runs later. Coroutines cannot be entered recursively
	212	* so avoid doing that!
	213	*/
a75e4e43	214	assert(luringcb->co->ctx == s->aio_context);
6663a0a3 AM	215	if (!qemu_coroutine_entered(luringcb->co)) {
	216	aio_co_wake(luringcb->co);
	217	}
	218	}
	219	qemu_bh_cancel(s->completion_bh);
	220	}
	221
	222	static int ioq_submit(LuringState *s)
	223	{
	224	int ret = 0;
	225	LuringAIOCB luringcb, luringcb_next;
	226
	227	while (s->io_q.in_queue > 0) {
	228	/*
	229	* Try to fetch sqes from the ring for requests waiting in
	230	* the overflow queue
	231	*/
	232	QSIMPLEQ_FOREACH_SAFE(luringcb, &s->io_q.submit_queue, next,
	233	luringcb_next) {
	234	struct io_uring_sqe *sqes = io_uring_get_sqe(&s->ring);
	235	if (!sqes) {
	236	break;
	237	}
	238	/* Prep sqe for submission */
	239	*sqes = luringcb->sqeq;
	240	QSIMPLEQ_REMOVE_HEAD(&s->io_q.submit_queue, next);
	241	}
	242	ret = io_uring_submit(&s->ring);
d803f590	243	trace_luring_io_uring_submit(s, ret);
6663a0a3 AM	244	/* Prevent infinite loop if submission is refused */
6663a0a3 AM	245	if (ret <= 0) {
b4e44c99	246	if (ret == -EAGAIN \|\| ret == -EINTR) {
6663a0a3 AM	247	continue;
	248	}
	249	break;
	250	}
	251	s->io_q.in_flight += ret;
	252	s->io_q.in_queue -= ret;
	253	}
	254	s->io_q.blocked = (s->io_q.in_queue > 0);
	255
	256	if (s->io_q.in_flight) {
	257	/*
	258	* We can try to complete something just right away if there are
	259	* still requests in-flight.
	260	*/
	261	luring_process_completions(s);
	262	}
	263	return ret;
	264	}
	265
	266	static void luring_process_completions_and_submit(LuringState *s)
	267	{
6663a0a3 AM	268	luring_process_completions(s);
6663a0a3 AM	269
6a6da231	270	if (s->io_q.in_queue > 0) {
6663a0a3 AM	271	ioq_submit(s);
6663a0a3 AM	272	}
6663a0a3 AM	273	}
	274
	275	static void qemu_luring_completion_bh(void *opaque)
	276	{
	277	LuringState *s = opaque;
	278	luring_process_completions_and_submit(s);
	279	}
	280
	281	static void qemu_luring_completion_cb(void *opaque)
	282	{
	283	LuringState *s = opaque;
	284	luring_process_completions_and_submit(s);
	285	}
	286
daffeb02 AM	287	static bool qemu_luring_poll_cb(void *opaque)
	288	{
	289	LuringState *s = opaque;
daffeb02	290
826cc324 SH	291	return io_uring_cq_ready(&s->ring);
	292	}
	293
	294	static void qemu_luring_poll_ready(void *opaque)
	295	{
	296	LuringState *s = opaque;
daffeb02	297
826cc324	298	luring_process_completions_and_submit(s);
daffeb02 AM	299	}
daffeb02 AM	300
6663a0a3 AM	301	static void ioq_init(LuringQueue *io_q)
	302	{
	303	QSIMPLEQ_INIT(&io_q->submit_queue);
6663a0a3 AM	304	io_q->in_queue = 0;
	305	io_q->in_flight = 0;
	306	io_q->blocked = false;
	307	}
	308
6a6da231	309	static void luring_unplug_fn(void *opaque)
6663a0a3	310	{
6a6da231 SH	311	LuringState *s = opaque;
	312	trace_luring_unplug_fn(s, s->io_q.blocked, s->io_q.in_queue,
	313	s->io_q.in_flight);
	314	if (!s->io_q.blocked && s->io_q.in_queue > 0) {
6663a0a3 AM	315	ioq_submit(s);
	316	}
	317	}
	318
	319	/**
	320	* luring_do_submit:
	321	* @fd: file descriptor for I/O
	322	* @luringcb: AIO control block
	323	* @s: AIO state
	324	* @offset: offset for request
	325	* @type: type of request
	326	*
	327	* Fetches sqes from ring, adds to pending queue and preps them
	328	*
	329	*/
	330	static int luring_do_submit(int fd, LuringAIOCB luringcb, LuringState s,
	331	uint64_t offset, int type)
	332	{
d803f590	333	int ret;
6663a0a3 AM	334	struct io_uring_sqe *sqes = &luringcb->sqeq;
	335
	336	switch (type) {
	337	case QEMU_AIO_WRITE:
	338	io_uring_prep_writev(sqes, fd, luringcb->qiov->iov,
	339	luringcb->qiov->niov, offset);
	340	break;
4751d09a SL	341	case QEMU_AIO_ZONE_APPEND:
	342	io_uring_prep_writev(sqes, fd, luringcb->qiov->iov,
	343	luringcb->qiov->niov, offset);
	344	break;
6663a0a3 AM	345	case QEMU_AIO_READ:
	346	io_uring_prep_readv(sqes, fd, luringcb->qiov->iov,
	347	luringcb->qiov->niov, offset);
	348	break;
	349	case QEMU_AIO_FLUSH:
	350	io_uring_prep_fsync(sqes, fd, IORING_FSYNC_DATASYNC);
	351	break;
	352	default:
	353	fprintf(stderr, "%s: invalid AIO request type, aborting 0x%x.\n",
	354	__func__, type);
	355	abort();
	356	}
	357	io_uring_sqe_set_data(sqes, luringcb);
	358
	359	QSIMPLEQ_INSERT_TAIL(&s->io_q.submit_queue, luringcb, next);
	360	s->io_q.in_queue++;
6a6da231 SH	361	trace_luring_do_submit(s, s->io_q.blocked, s->io_q.in_queue,
	362	s->io_q.in_flight);
	363	if (!s->io_q.blocked) {
	364	if (s->io_q.in_flight + s->io_q.in_queue >= MAX_ENTRIES) {
	365	ret = ioq_submit(s);
	366	trace_luring_do_submit_done(s, ret);
	367	return ret;
	368	}
	369
	370	blk_io_plug_call(luring_unplug_fn, s);
6663a0a3 AM	371	}
	372	return 0;
	373	}
	374
a75e4e43 EGE	375	int coroutine_fn luring_co_submit(BlockDriverState *bs, int fd, uint64_t offset,
a75e4e43 EGE	376	QEMUIOVector *qiov, int type)
6663a0a3 AM	377	{
6663a0a3 AM	378	int ret;
a75e4e43 EGE	379	AioContext *ctx = qemu_get_current_aio_context();
a75e4e43 EGE	380	LuringState *s = aio_get_linux_io_uring(ctx);
6663a0a3 AM	381	LuringAIOCB luringcb = {
	382	.co = qemu_coroutine_self(),
	383	.ret = -EINPROGRESS,
	384	.qiov = qiov,
	385	.is_read = (type == QEMU_AIO_READ),
	386	};
d803f590 AM	387	trace_luring_co_submit(bs, s, &luringcb, fd, offset, qiov ? qiov->size : 0,
d803f590 AM	388	type);
6663a0a3	389	ret = luring_do_submit(fd, &luringcb, s, offset, type);
d803f590	390
6663a0a3 AM	391	if (ret < 0) {
	392	return ret;
	393	}
	394
	395	if (luringcb.ret == -EINPROGRESS) {
	396	qemu_coroutine_yield();
	397	}
	398	return luringcb.ret;
	399	}
	400
	401	void luring_detach_aio_context(LuringState s, AioContext old_context)
	402	{
60f782b6	403	aio_set_fd_handler(old_context, s->ring.ring_fd,
826cc324	404	NULL, NULL, NULL, NULL, s);
6663a0a3 AM	405	qemu_bh_delete(s->completion_bh);
	406	s->aio_context = NULL;
	407	}
	408
	409	void luring_attach_aio_context(LuringState s, AioContext new_context)
	410	{
	411	s->aio_context = new_context;
	412	s->completion_bh = aio_bh_new(new_context, qemu_luring_completion_bh, s);
60f782b6	413	aio_set_fd_handler(s->aio_context, s->ring.ring_fd,
826cc324 SH	414	qemu_luring_completion_cb, NULL,
826cc324 SH	415	qemu_luring_poll_cb, qemu_luring_poll_ready, s);
6663a0a3 AM	416	}
	417
	418	LuringState luring_init(Error *errp)
	419	{
	420	int rc;
	421	LuringState *s = g_new0(LuringState, 1);
	422	struct io_uring *ring = &s->ring;
	423
d803f590 AM	424	trace_luring_init_state(s, sizeof(*s));
d803f590 AM	425
6663a0a3 AM	426	rc = io_uring_queue_init(MAX_ENTRIES, ring, 0);
	427	if (rc < 0) {
	428	error_setg_errno(errp, errno, "failed to init linux io_uring ring");
	429	g_free(s);
	430	return NULL;
	431	}
	432
	433	ioq_init(&s->io_q);
e2848bc5	434	return s;
7845e731	435
6663a0a3 AM	436	}
	437
	438	void luring_cleanup(LuringState *s)
	439	{
	440	io_uring_queue_exit(&s->ring);
d803f590	441	trace_luring_cleanup_state(s);
bd89f936	442	g_free(s);
6663a0a3	443	}