Exemplo n.º 1
0
static void
alq_shutdown(struct alq *alq)
{
    ALQ_LOCK(alq);

    /* Stop any new writers. */
    alq->aq_flags |= AQ_SHUTDOWN;

    /*
     * If the ALQ isn't active but has unwritten data (possible if
     * the ALQ_NOACTIVATE flag has been used), explicitly activate the
     * ALQ here so that the pending data gets flushed by the ald_daemon.
     */
    if (!(alq->aq_flags & AQ_ACTIVE) && HAS_PENDING_DATA(alq)) {
        alq->aq_flags |= AQ_ACTIVE;
        ALQ_UNLOCK(alq);
        ALD_LOCK();
        ald_activate(alq);
        ALD_UNLOCK();
        ALQ_LOCK(alq);
    }

    /* Drain IO */
    while (alq->aq_flags & AQ_ACTIVE) {
        alq->aq_flags |= AQ_WANTED;
        msleep_spin(alq, &alq->aq_mtx, "aldclose", 0);
    }
    ALQ_UNLOCK(alq);

    vn_close(alq->aq_vp, FWRITE, alq->aq_cred,
             curthread);
    crfree(alq->aq_cred);
}
Exemplo n.º 2
0
void
alq_flush(struct alq *alq)
{
    int needwakeup = 0;

    ALD_LOCK();
    ALQ_LOCK(alq);

    /*
     * Pull the lever iff there is data to flush and we're
     * not already in the middle of a flush operation.
     */
    if (HAS_PENDING_DATA(alq) && !(alq->aq_flags & AQ_FLUSHING)) {
        if (alq->aq_flags & AQ_ACTIVE)
            ald_deactivate(alq);

        ALD_UNLOCK();
        needwakeup = alq_doio(alq);
    } else
        ALD_UNLOCK();

    ALQ_UNLOCK(alq);

    if (needwakeup)
        wakeup_one(alq);
}
Exemplo n.º 3
0
struct ale *
alq_get(struct alq *alq, int waitok)
{
	struct ale *ale;
	struct ale *aln;

	ale = NULL;

	ALQ_LOCK(alq);

	/* Loop until we get an entry or we're shutting down */
	while ((alq->aq_flags & AQ_SHUTDOWN) == 0 && 
	    (ale = alq->aq_entfree) == NULL &&
	    (waitok & ALQ_WAITOK)) {
		alq->aq_flags |= AQ_WANTED;
		msleep_spin(alq, &alq->aq_mtx, "alqget", 0);
	}

	if (ale != NULL) {
		aln = ale->ae_next;
		if ((aln->ae_flags & AE_VALID) == 0)
			alq->aq_entfree = aln;
		else
			alq->aq_entfree = NULL;
	} else
		ALQ_UNLOCK(alq);


	return (ale);
}
Exemplo n.º 4
0
static void
ald_daemon(void)
{
	int needwakeup;
	struct alq *alq;

	ald_thread = FIRST_THREAD_IN_PROC(ald_proc);

	EVENTHANDLER_REGISTER(shutdown_pre_sync, ald_shutdown, NULL,
	    SHUTDOWN_PRI_FIRST);

	ALD_LOCK();

	for (;;) {
		while ((alq = LIST_FIRST(&ald_active)) == NULL)
			msleep(&ald_active, &ald_mtx, PWAIT, "aldslp", 0);

		ALQ_LOCK(alq);
		ald_deactivate(alq);
		ALD_UNLOCK();
		needwakeup = alq_doio(alq);
		ALQ_UNLOCK(alq);
		if (needwakeup)
			wakeup(alq);
		ALD_LOCK();
	}
}
Exemplo n.º 5
0
void
alq_flush(struct alq *alq)
{
	int needwakeup = 0;

	ALD_LOCK();
	ALQ_LOCK(alq);
	if (alq->aq_flags & AQ_ACTIVE) {
		ald_deactivate(alq);
		ALD_UNLOCK();
		needwakeup = alq_doio(alq);
	} else
		ALD_UNLOCK();
	ALQ_UNLOCK(alq);

	if (needwakeup)
		wakeup(alq);
}
Exemplo n.º 6
0
static void
alq_shutdown(struct alq *alq)
{
	ALQ_LOCK(alq);

	/* Stop any new writers. */
	alq->aq_flags |= AQ_SHUTDOWN;

	/* Drain IO */
	while (alq->aq_flags & (AQ_FLUSHING|AQ_ACTIVE)) {
		alq->aq_flags |= AQ_WANTED;
		msleep_spin(alq, &alq->aq_mtx, "aldclose", 0);
	}
	ALQ_UNLOCK(alq);

	vn_close(alq->aq_vp, FWRITE, alq->aq_cred,
	    curthread);
	crfree(alq->aq_cred);
}
Exemplo n.º 7
0
static void
ald_daemon(void)
{
    int needwakeup;
    struct alq *alq;

    ald_thread = FIRST_THREAD_IN_PROC(ald_proc);

    alq_eventhandler_tag = EVENTHANDLER_REGISTER(shutdown_pre_sync,
                           ald_shutdown, NULL, SHUTDOWN_PRI_FIRST);

    ALD_LOCK();

    for (;;) {
        while ((alq = BSD_LIST_FIRST(&ald_active)) == NULL &&
                !ald_shutingdown)
            mtx_sleep(&ald_active, &ald_mtx, PWAIT, "aldslp", 0);

        /* Don't shutdown until all active ALQs are flushed. */
        if (ald_shutingdown && alq == NULL) {
            ALD_UNLOCK();
            break;
        }

        ALQ_LOCK(alq);
        ald_deactivate(alq);
        ALD_UNLOCK();
        needwakeup = alq_doio(alq);
        ALQ_UNLOCK(alq);
        if (needwakeup)
            wakeup_one(alq);
        ALD_LOCK();
    }

    kproc_exit(0);
}
Exemplo n.º 8
0
/*
 * Retrieve a pointer for the ALQ to write directly into, avoiding bcopy.
 */
struct ale *
alq_getn(struct alq *alq, int len, int flags)
{
    int contigbytes;
    void *waitchan;

    KASSERT((len > 0 && len <= alq->aq_buflen),
            ("%s: len <= 0 || len > alq->aq_buflen", __func__));

    waitchan = NULL;

    ALQ_LOCK(alq);

    /*
     * Determine the number of free contiguous bytes.
     * We ensure elsewhere that if aq_writehead == aq_writetail because
     * the buffer is empty, they will both be set to 0 and therefore
     * aq_freebytes == aq_buflen and is fully contiguous.
     * If they are equal and the buffer is not empty, aq_freebytes will
     * be 0 indicating the buffer is full.
     */
    if (alq->aq_writehead <= alq->aq_writetail)
        contigbytes = alq->aq_freebytes;
    else {
        contigbytes = alq->aq_buflen - alq->aq_writehead;

        if (contigbytes < len) {
            /*
             * Insufficient space at end of buffer to handle a
             * contiguous write. Wrap early if there's space at
             * the beginning. This will leave a hole at the end
             * of the buffer which we will have to skip over when
             * flushing the buffer to disk.
             */
            if (alq->aq_writetail >= len || flags & ALQ_WAITOK) {
                /* Keep track of # bytes left blank. */
                alq->aq_wrapearly = contigbytes;
                /* Do the wrap and adjust counters. */
                contigbytes = alq->aq_freebytes =
                                  alq->aq_writetail;
                alq->aq_writehead = 0;
            }
        }
    }

    /*
     * Return a NULL ALE if:
     * - The message is larger than our underlying buffer.
     * - The ALQ is being shutdown.
     * - There is insufficient free space in our underlying buffer
     *   to accept the message and the user can't wait for space.
     * - There is insufficient free space in our underlying buffer
     *   to accept the message and the alq is inactive due to prior
     *   use of the ALQ_NOACTIVATE flag (which would lead to deadlock).
     */
    if (len > alq->aq_buflen ||
            alq->aq_flags & AQ_SHUTDOWN ||
            (((flags & ALQ_NOWAIT) || (!(alq->aq_flags & AQ_ACTIVE) &&
                                       HAS_PENDING_DATA(alq))) && contigbytes < len)) {
        ALQ_UNLOCK(alq);
        return (NULL);
    }

    /*
     * If we want ordered writes and there is already at least one thread
     * waiting for resources to become available, sleep until we're woken.
     */
    if (alq->aq_flags & AQ_ORDERED && alq->aq_waiters > 0) {
        KASSERT(!(flags & ALQ_NOWAIT),
                ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__));
        alq->aq_waiters++;
        msleep_spin(&alq->aq_waiters, &alq->aq_mtx, "alqgnord", 0);
        alq->aq_waiters--;
    }

    /*
     * (ALQ_WAITOK && contigbytes < len) or contigbytes >= len, either enter
     * while loop and sleep until we have enough contiguous free bytes
     * (former) or skip (latter). If AQ_ORDERED is set, only 1 thread at a
     * time will be in this loop. Otherwise, multiple threads may be
     * sleeping here competing for ALQ resources.
     */
    while (contigbytes < len && !(alq->aq_flags & AQ_SHUTDOWN)) {
        KASSERT(!(flags & ALQ_NOWAIT),
                ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__));
        alq->aq_flags |= AQ_WANTED;
        alq->aq_waiters++;
        if (waitchan)
            wakeup(waitchan);
        msleep_spin(alq, &alq->aq_mtx, "alqgnres", 0);
        alq->aq_waiters--;

        if (alq->aq_writehead <= alq->aq_writetail)
            contigbytes = alq->aq_freebytes;
        else
            contigbytes = alq->aq_buflen - alq->aq_writehead;

        /*
         * If we're the first thread to wake after an AQ_WANTED wakeup
         * but there isn't enough free space for us, we're going to loop
         * and sleep again. If there are other threads waiting in this
         * loop, schedule a wakeup so that they can see if the space
         * they require is available.
         */
        if (alq->aq_waiters > 0 && !(alq->aq_flags & AQ_ORDERED) &&
                contigbytes < len && !(alq->aq_flags & AQ_WANTED))
            waitchan = alq;
        else
            waitchan = NULL;
    }

    /*
     * If there are waiters, we need to signal the waiting threads after we
     * complete our work. The alq ptr is used as a wait channel for threads
     * requiring resources to be freed up. In the AQ_ORDERED case, threads
     * are not allowed to concurrently compete for resources in the above
     * while loop, so we use a different wait channel in this case.
     */
    if (alq->aq_waiters > 0) {
        if (alq->aq_flags & AQ_ORDERED)
            waitchan = &alq->aq_waiters;
        else
            waitchan = alq;
    } else
        waitchan = NULL;

    /* Bail if we're shutting down. */
    if (alq->aq_flags & AQ_SHUTDOWN) {
        ALQ_UNLOCK(alq);
        if (waitchan != NULL)
            wakeup_one(waitchan);
        return (NULL);
    }

    /*
     * If we are here, we have a contiguous number of bytes >= len
     * available in our buffer starting at aq_writehead.
     */
    alq->aq_getpost.ae_data = alq->aq_entbuf + alq->aq_writehead;
    alq->aq_getpost.ae_bytesused = len;

    return (&alq->aq_getpost);
}
Exemplo n.º 9
0
/*
 * Copy a new entry into the queue.  If the operation would block either
 * wait or return an error depending on the value of waitok.
 */
int
alq_writen(struct alq *alq, void *data, int len, int flags)
{
    int activate, copy, ret;
    void *waitchan;

    KASSERT((len > 0 && len <= alq->aq_buflen),
            ("%s: len <= 0 || len > aq_buflen", __func__));

    activate = ret = 0;
    copy = len;
    waitchan = NULL;

    ALQ_LOCK(alq);

    /*
     * Fail to perform the write and return EWOULDBLOCK if:
     * - The message is larger than our underlying buffer.
     * - The ALQ is being shutdown.
     * - There is insufficient free space in our underlying buffer
     *   to accept the message and the user can't wait for space.
     * - There is insufficient free space in our underlying buffer
     *   to accept the message and the alq is inactive due to prior
     *   use of the ALQ_NOACTIVATE flag (which would lead to deadlock).
     */
    if (len > alq->aq_buflen ||
            alq->aq_flags & AQ_SHUTDOWN ||
            (((flags & ALQ_NOWAIT) || (!(alq->aq_flags & AQ_ACTIVE) &&
                                       HAS_PENDING_DATA(alq))) && alq->aq_freebytes < len)) {
        ALQ_UNLOCK(alq);
        return (EWOULDBLOCK);
    }

    /*
     * If we want ordered writes and there is already at least one thread
     * waiting for resources to become available, sleep until we're woken.
     */
    if (alq->aq_flags & AQ_ORDERED && alq->aq_waiters > 0) {
        KASSERT(!(flags & ALQ_NOWAIT),
                ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__));
        alq->aq_waiters++;
        msleep_spin(&alq->aq_waiters, &alq->aq_mtx, "alqwnord", 0);
        alq->aq_waiters--;
    }

    /*
     * (ALQ_WAITOK && aq_freebytes < len) or aq_freebytes >= len, either
     * enter while loop and sleep until we have enough free bytes (former)
     * or skip (latter). If AQ_ORDERED is set, only 1 thread at a time will
     * be in this loop. Otherwise, multiple threads may be sleeping here
     * competing for ALQ resources.
     */
    while (alq->aq_freebytes < len && !(alq->aq_flags & AQ_SHUTDOWN)) {
        KASSERT(!(flags & ALQ_NOWAIT),
                ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__));
        alq->aq_flags |= AQ_WANTED;
        alq->aq_waiters++;
        if (waitchan)
            wakeup(waitchan);
        msleep_spin(alq, &alq->aq_mtx, "alqwnres", 0);
        alq->aq_waiters--;

        /*
         * If we're the first thread to wake after an AQ_WANTED wakeup
         * but there isn't enough free space for us, we're going to loop
         * and sleep again. If there are other threads waiting in this
         * loop, schedule a wakeup so that they can see if the space
         * they require is available.
         */
        if (alq->aq_waiters > 0 && !(alq->aq_flags & AQ_ORDERED) &&
                alq->aq_freebytes < len && !(alq->aq_flags & AQ_WANTED))
            waitchan = alq;
        else
            waitchan = NULL;
    }

    /*
     * If there are waiters, we need to signal the waiting threads after we
     * complete our work. The alq ptr is used as a wait channel for threads
     * requiring resources to be freed up. In the AQ_ORDERED case, threads
     * are not allowed to concurrently compete for resources in the above
     * while loop, so we use a different wait channel in this case.
     */
    if (alq->aq_waiters > 0) {
        if (alq->aq_flags & AQ_ORDERED)
            waitchan = &alq->aq_waiters;
        else
            waitchan = alq;
    } else
        waitchan = NULL;

    /* Bail if we're shutting down. */
    if (alq->aq_flags & AQ_SHUTDOWN) {
        ret = EWOULDBLOCK;
        goto unlock;
    }

    /*
     * If we need to wrap the buffer to accommodate the write,
     * we'll need 2 calls to bcopy.
     */
    if ((alq->aq_buflen - alq->aq_writehead) < len)
        copy = alq->aq_buflen - alq->aq_writehead;

    /* Copy message (or part thereof if wrap required) to the buffer. */
    bcopy(data, alq->aq_entbuf + alq->aq_writehead, copy);
    alq->aq_writehead += copy;

    if (alq->aq_writehead >= alq->aq_buflen) {
        KASSERT((alq->aq_writehead == alq->aq_buflen),
                ("%s: alq->aq_writehead (%d) > alq->aq_buflen (%d)",
                 __func__,
                 alq->aq_writehead,
                 alq->aq_buflen));
        alq->aq_writehead = 0;
    }

    if (copy != len) {
        /*
         * Wrap the buffer by copying the remainder of our message
         * to the start of the buffer and resetting aq_writehead.
         */
        bcopy(((uint8_t *)data)+copy, alq->aq_entbuf, len - copy);
        alq->aq_writehead = len - copy;
    }

    KASSERT((alq->aq_writehead >= 0 && alq->aq_writehead < alq->aq_buflen),
            ("%s: aq_writehead < 0 || aq_writehead >= aq_buflen", __func__));

    alq->aq_freebytes -= len;

    if (!(alq->aq_flags & AQ_ACTIVE) && !(flags & ALQ_NOACTIVATE)) {
        alq->aq_flags |= AQ_ACTIVE;
        activate = 1;
    }

    KASSERT((HAS_PENDING_DATA(alq)), ("%s: queue empty!", __func__));

unlock:
    ALQ_UNLOCK(alq);

    if (activate) {
        ALD_LOCK();
        ald_activate(alq);
        ALD_UNLOCK();
    }

    /* NB: We rely on wakeup_one waking threads in a FIFO manner. */
    if (waitchan != NULL)
        wakeup_one(waitchan);

    return (ret);
}
Exemplo n.º 10
0
/*
 * Flush all pending data to disk.  This operation will block.
 */
static int
alq_doio(struct alq *alq)
{
    struct thread *td;
    struct mount *mp;
    struct vnode *vp;
    struct uio auio;
    struct iovec aiov[2];
    int totlen;
    int iov;
    int vfslocked;
    int wrapearly;

    KASSERT((HAS_PENDING_DATA(alq)), ("%s: queue empty!", __func__));

    vp = alq->aq_vp;
    td = curthread;
    totlen = 0;
    iov = 1;
    wrapearly = alq->aq_wrapearly;

    bzero(&aiov, sizeof(aiov));
    bzero(&auio, sizeof(auio));

    /* Start the write from the location of our buffer tail pointer. */
    aiov[0].iov_base = alq->aq_entbuf + alq->aq_writetail;

    if (alq->aq_writetail < alq->aq_writehead) {
        /* Buffer not wrapped. */
        totlen = aiov[0].iov_len = alq->aq_writehead - alq->aq_writetail;
    } else if (alq->aq_writehead == 0) {
        /* Buffer not wrapped (special case to avoid an empty iov). */
        totlen = aiov[0].iov_len = alq->aq_buflen - alq->aq_writetail -
                                   wrapearly;
    } else {
        /*
         * Buffer wrapped, requires 2 aiov entries:
         * - first is from writetail to end of buffer
         * - second is from start of buffer to writehead
         */
        aiov[0].iov_len = alq->aq_buflen - alq->aq_writetail -
                          wrapearly;
        iov++;
        aiov[1].iov_base = alq->aq_entbuf;
        aiov[1].iov_len =  alq->aq_writehead;
        totlen = aiov[0].iov_len + aiov[1].iov_len;
    }

    alq->aq_flags |= AQ_FLUSHING;
    ALQ_UNLOCK(alq);

    auio.uio_iov = &aiov[0];
    auio.uio_offset = 0;
    auio.uio_segflg = UIO_SYSSPACE;
    auio.uio_rw = UIO_WRITE;
    auio.uio_iovcnt = iov;
    auio.uio_resid = totlen;
    auio.uio_td = td;

    /*
     * Do all of the junk required to write now.
     */
    vfslocked = VFS_LOCK_GIANT(vp->v_mount);
    vn_start_write(vp, &mp, V_WAIT);
    vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    /*
     * XXX: VOP_WRITE error checks are ignored.
     */
#ifdef MAC
    if (mac_vnode_check_write(alq->aq_cred, NOCRED, vp) == 0)
#endif
        VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, alq->aq_cred);
    VOP_UNLOCK(vp, 0);
    vn_finished_write(mp);
    VFS_UNLOCK_GIANT(vfslocked);

    ALQ_LOCK(alq);
    alq->aq_flags &= ~AQ_FLUSHING;

    /* Adjust writetail as required, taking into account wrapping. */
    alq->aq_writetail = (alq->aq_writetail + totlen + wrapearly) %
                        alq->aq_buflen;
    alq->aq_freebytes += totlen + wrapearly;

    /*
     * If we just flushed part of the buffer which wrapped, reset the
     * wrapearly indicator.
     */
    if (wrapearly)
        alq->aq_wrapearly = 0;

    /*
     * If we just flushed the buffer completely, reset indexes to 0 to
     * minimise buffer wraps.
     * This is also required to ensure alq_getn() can't wedge itself.
     */
    if (!HAS_PENDING_DATA(alq))
        alq->aq_writehead = alq->aq_writetail = 0;

    KASSERT((alq->aq_writetail >= 0 && alq->aq_writetail < alq->aq_buflen),
            ("%s: aq_writetail < 0 || aq_writetail >= aq_buflen", __func__));

    if (alq->aq_flags & AQ_WANTED) {
        alq->aq_flags &= ~AQ_WANTED;
        return (1);
    }

    return(0);
}
Exemplo n.º 11
0
/*
 * Flush all pending data to disk.  This operation will block.
 */
static int
alq_doio(struct alq *alq)
{
	struct thread *td;
	struct mount *mp;
	struct vnode *vp;
	struct uio auio;
	struct iovec aiov[2];
	struct ale *ale;
	struct ale *alstart;
	int totlen;
	int iov;
	int vfslocked;

	vp = alq->aq_vp;
	td = curthread;
	totlen = 0;
	iov = 0;

	alstart = ale = alq->aq_entvalid;
	alq->aq_entvalid = NULL;

	bzero(&aiov, sizeof(aiov));
	bzero(&auio, sizeof(auio));

	do {
		if (aiov[iov].iov_base == NULL)
			aiov[iov].iov_base = ale->ae_data;
		aiov[iov].iov_len += alq->aq_entlen;
		totlen += alq->aq_entlen;
		/* Check to see if we're wrapping the buffer */
		if (ale->ae_data + alq->aq_entlen != ale->ae_next->ae_data)
			iov++;
		ale->ae_flags &= ~AE_VALID;
		ale = ale->ae_next;
	} while (ale->ae_flags & AE_VALID);

	alq->aq_flags |= AQ_FLUSHING;
	ALQ_UNLOCK(alq);

	if (iov == 2 || aiov[iov].iov_base == NULL)
		iov--;

	auio.uio_iov = &aiov[0];
	auio.uio_offset = 0;
	auio.uio_segflg = UIO_SYSSPACE;
	auio.uio_rw = UIO_WRITE;
	auio.uio_iovcnt = iov + 1;
	auio.uio_resid = totlen;
	auio.uio_td = td;

	/*
	 * Do all of the junk required to write now.
	 */
	vfslocked = VFS_LOCK_GIANT(vp->v_mount);
	vn_start_write(vp, &mp, V_WAIT);
	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
	/*
	 * XXX: VOP_WRITE error checks are ignored.
	 */
#ifdef MAC
	if (mac_vnode_check_write(alq->aq_cred, NOCRED, vp) == 0)
#endif
		VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, alq->aq_cred);
	VOP_UNLOCK(vp, 0);
	vn_finished_write(mp);
	VFS_UNLOCK_GIANT(vfslocked);

	ALQ_LOCK(alq);
	alq->aq_flags &= ~AQ_FLUSHING;

	if (alq->aq_entfree == NULL)
		alq->aq_entfree = alstart;

	if (alq->aq_flags & AQ_WANTED) {
		alq->aq_flags &= ~AQ_WANTED;
		return (1);
	}

	return(0);
}