2 * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
3 * Copyright (c) 2008-2009, Lawrence Stewart <lstewart@freebsd.org>
4 * Copyright (c) 2009-2010, The FreeBSD Foundation
7 * Portions of this software were developed at the Centre for Advanced
8 * Internet Architectures, Swinburne University of Technology, Melbourne,
9 * Australia by Lawrence Stewart under sponsorship from the FreeBSD Foundation.
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
14 * 1. Redistributions of source code must retain the above copyright
15 * notice unmodified, this list of conditions, and the following
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/kernel.h>
41 #include <sys/kthread.h>
43 #include <sys/mount.h>
44 #include <sys/mutex.h>
45 #include <sys/namei.h>
47 #include <sys/vnode.h>
49 #include <sys/malloc.h>
50 #include <sys/unistd.h>
51 #include <sys/fcntl.h>
52 #include <sys/eventhandler.h>
54 #include <security/mac/mac_framework.h>
56 /* Async. Logging Queue */
58 char *aq_entbuf; /* Buffer for stored entries */
59 int aq_entmax; /* Max entries */
60 int aq_entlen; /* Entry length */
61 int aq_freebytes; /* Bytes available in buffer */
62 int aq_buflen; /* Total length of our buffer */
63 int aq_writehead; /* Location for next write */
64 int aq_writetail; /* Flush starts at this location */
65 int aq_wrapearly; /* # bytes left blank at end of buf */
66 int aq_flags; /* Queue flags */
67 int aq_waiters; /* Num threads waiting for resources
68 * NB: Used as a wait channel so must
69 * not be first field in the alq struct
71 struct ale aq_getpost; /* ALE for use by get/post */
72 struct mtx aq_mtx; /* Queue lock */
73 struct vnode *aq_vp; /* Open vnode handle */
74 struct ucred *aq_cred; /* Credentials of the opening thread */
75 LIST_ENTRY(alq) aq_act; /* List of active queues */
76 LIST_ENTRY(alq) aq_link; /* List of all queues */
79 #define AQ_WANTED 0x0001 /* Wakeup sleeper when io is done */
80 #define AQ_ACTIVE 0x0002 /* on the active list */
81 #define AQ_FLUSHING 0x0004 /* doing IO */
82 #define AQ_SHUTDOWN 0x0008 /* Queue no longer valid */
83 #define AQ_ORDERED 0x0010 /* Queue enforces ordered writes */
84 #define AQ_LEGACY 0x0020 /* Legacy queue (fixed length writes) */
86 #define ALQ_LOCK(alq) mtx_lock_spin(&(alq)->aq_mtx)
87 #define ALQ_UNLOCK(alq) mtx_unlock_spin(&(alq)->aq_mtx)
89 #define HAS_PENDING_DATA(alq) ((alq)->aq_freebytes != (alq)->aq_buflen)
91 static MALLOC_DEFINE(M_ALD, "ALD", "ALD");
94 * The ald_mtx protects the ald_queues list and the ald_active list.
96 static struct mtx ald_mtx;
97 static LIST_HEAD(, alq) ald_queues;
98 static LIST_HEAD(, alq) ald_active;
99 static int ald_shutingdown = 0;
100 struct thread *ald_thread;
101 static struct proc *ald_proc;
103 #define ALD_LOCK() mtx_lock(&ald_mtx)
104 #define ALD_UNLOCK() mtx_unlock(&ald_mtx)
106 /* Daemon functions */
107 static int ald_add(struct alq *);
108 static int ald_rem(struct alq *);
109 static void ald_startup(void *);
110 static void ald_daemon(void);
111 static void ald_shutdown(void *, int);
112 static void ald_activate(struct alq *);
113 static void ald_deactivate(struct alq *);
115 /* Internal queue functions */
116 static void alq_shutdown(struct alq *);
117 static void alq_destroy(struct alq *);
118 static int alq_doio(struct alq *);
122 * Add a new queue to the global list. Fail if we're shutting down.
125 ald_add(struct alq *alq)
132 if (ald_shutingdown) {
136 LIST_INSERT_HEAD(&ald_queues, alq, aq_link);
143 * Remove a queue from the global list unless we're shutting down. If so,
144 * the ald will take care of cleaning up it's resources.
147 ald_rem(struct alq *alq)
154 if (ald_shutingdown) {
158 LIST_REMOVE(alq, aq_link);
165 * Put a queue on the active list. This will schedule it for writing.
168 ald_activate(struct alq *alq)
170 LIST_INSERT_HEAD(&ald_active, alq, aq_act);
175 ald_deactivate(struct alq *alq)
177 LIST_REMOVE(alq, aq_act);
178 alq->aq_flags &= ~AQ_ACTIVE;
182 ald_startup(void *unused)
184 mtx_init(&ald_mtx, "ALDmtx", NULL, MTX_DEF|MTX_QUIET);
185 LIST_INIT(&ald_queues);
186 LIST_INIT(&ald_active);
195 ald_thread = FIRST_THREAD_IN_PROC(ald_proc);
197 EVENTHANDLER_REGISTER(shutdown_pre_sync, ald_shutdown, NULL,
203 while ((alq = LIST_FIRST(&ald_active)) == NULL &&
205 mtx_sleep(&ald_active, &ald_mtx, PWAIT, "aldslp", 0);
207 /* Don't shutdown until all active ALQs are flushed. */
208 if (ald_shutingdown && alq == NULL) {
216 needwakeup = alq_doio(alq);
227 ald_shutdown(void *arg, int howto)
233 /* Ensure no new queues can be created. */
236 /* Shutdown all ALQs prior to terminating the ald_daemon. */
237 while ((alq = LIST_FIRST(&ald_queues)) != NULL) {
238 LIST_REMOVE(alq, aq_link);
244 /* At this point, all ALQs are flushed and shutdown. */
247 * Wake ald_daemon so that it exits. It won't be able to do
248 * anything until we mtx_sleep because we hold the ald_mtx.
252 /* Wait for ald_daemon to exit. */
253 mtx_sleep(ald_proc, &ald_mtx, PWAIT, "aldslp", 0);
259 alq_shutdown(struct alq *alq)
263 /* Stop any new writers. */
264 alq->aq_flags |= AQ_SHUTDOWN;
267 * If the ALQ isn't active but has unwritten data (possible if
268 * the ALQ_NOACTIVATE flag has been used), explicitly activate the
269 * ALQ here so that the pending data gets flushed by the ald_daemon.
271 if (!(alq->aq_flags & AQ_ACTIVE) && HAS_PENDING_DATA(alq)) {
272 alq->aq_flags |= AQ_ACTIVE;
281 while (alq->aq_flags & AQ_ACTIVE) {
282 alq->aq_flags |= AQ_WANTED;
283 msleep_spin(alq, &alq->aq_mtx, "aldclose", 0);
287 vn_close(alq->aq_vp, FWRITE, alq->aq_cred,
289 crfree(alq->aq_cred);
293 alq_destroy(struct alq *alq)
295 /* Drain all pending IO. */
298 mtx_destroy(&alq->aq_mtx);
299 free(alq->aq_entbuf, M_ALD);
304 * Flush all pending data to disk. This operation will block.
307 alq_doio(struct alq *alq)
313 struct iovec aiov[2];
319 KASSERT((HAS_PENDING_DATA(alq)), ("%s: queue empty!", __func__));
325 wrapearly = alq->aq_wrapearly;
327 bzero(&aiov, sizeof(aiov));
328 bzero(&auio, sizeof(auio));
330 /* Start the write from the location of our buffer tail pointer. */
331 aiov[0].iov_base = alq->aq_entbuf + alq->aq_writetail;
333 if (alq->aq_writetail < alq->aq_writehead) {
334 /* Buffer not wrapped. */
335 totlen = aiov[0].iov_len = alq->aq_writehead - alq->aq_writetail;
336 } else if (alq->aq_writehead == 0) {
337 /* Buffer not wrapped (special case to avoid an empty iov). */
338 totlen = aiov[0].iov_len = alq->aq_buflen - alq->aq_writetail -
342 * Buffer wrapped, requires 2 aiov entries:
343 * - first is from writetail to end of buffer
344 * - second is from start of buffer to writehead
346 aiov[0].iov_len = alq->aq_buflen - alq->aq_writetail -
349 aiov[1].iov_base = alq->aq_entbuf;
350 aiov[1].iov_len = alq->aq_writehead;
351 totlen = aiov[0].iov_len + aiov[1].iov_len;
354 alq->aq_flags |= AQ_FLUSHING;
357 auio.uio_iov = &aiov[0];
359 auio.uio_segflg = UIO_SYSSPACE;
360 auio.uio_rw = UIO_WRITE;
361 auio.uio_iovcnt = iov;
362 auio.uio_resid = totlen;
366 * Do all of the junk required to write now.
368 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
369 vn_start_write(vp, &mp, V_WAIT);
370 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
372 * XXX: VOP_WRITE error checks are ignored.
375 if (mac_vnode_check_write(alq->aq_cred, NOCRED, vp) == 0)
377 VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, alq->aq_cred);
379 vn_finished_write(mp);
380 VFS_UNLOCK_GIANT(vfslocked);
383 alq->aq_flags &= ~AQ_FLUSHING;
385 /* Adjust writetail as required, taking into account wrapping. */
386 alq->aq_writetail = (alq->aq_writetail + totlen + wrapearly) %
388 alq->aq_freebytes += totlen + wrapearly;
391 * If we just flushed part of the buffer which wrapped, reset the
392 * wrapearly indicator.
395 alq->aq_wrapearly = 0;
398 * If we just flushed the buffer completely, reset indexes to 0 to
399 * minimise buffer wraps.
400 * This is also required to ensure alq_getn() can't wedge itself.
402 if (!HAS_PENDING_DATA(alq))
403 alq->aq_writehead = alq->aq_writetail = 0;
405 KASSERT((alq->aq_writetail >= 0 && alq->aq_writetail < alq->aq_buflen),
406 ("%s: aq_writetail < 0 || aq_writetail >= aq_buflen", __func__));
408 if (alq->aq_flags & AQ_WANTED) {
409 alq->aq_flags &= ~AQ_WANTED;
416 static struct kproc_desc ald_kp = {
422 SYSINIT(aldthread, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, kproc_start, &ald_kp);
423 SYSINIT(ald, SI_SUB_LOCK, SI_ORDER_ANY, ald_startup, NULL);
426 /* User visible queue functions */
429 * Create the queue data structure, allocate the buffer, and open the file.
433 alq_open_flags(struct alq **alqp, const char *file, struct ucred *cred, int cmode,
443 KASSERT((size > 0), ("%s: size <= 0", __func__));
448 NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_SYSSPACE, file, td);
449 oflags = FWRITE | O_NOFOLLOW | O_CREAT;
451 error = vn_open_cred(&nd, &oflags, cmode, 0, cred, NULL);
455 vfslocked = NDHASGIANT(&nd);
456 NDFREE(&nd, NDF_ONLY_PNBUF);
457 /* We just unlock so we hold a reference */
458 VOP_UNLOCK(nd.ni_vp, 0);
459 VFS_UNLOCK_GIANT(vfslocked);
461 alq = malloc(sizeof(*alq), M_ALD, M_WAITOK|M_ZERO);
462 alq->aq_vp = nd.ni_vp;
463 alq->aq_cred = crhold(cred);
465 mtx_init(&alq->aq_mtx, "ALD Queue", NULL, MTX_SPIN|MTX_QUIET);
467 alq->aq_buflen = size;
471 alq->aq_freebytes = alq->aq_buflen;
472 alq->aq_entbuf = malloc(alq->aq_buflen, M_ALD, M_WAITOK|M_ZERO);
473 alq->aq_writehead = alq->aq_writetail = 0;
474 if (flags & ALQ_ORDERED)
475 alq->aq_flags |= AQ_ORDERED;
477 if ((error = ald_add(alq)) != 0) {
488 alq_open(struct alq **alqp, const char *file, struct ucred *cred, int cmode,
493 KASSERT((count >= 0), ("%s: count < 0", __func__));
496 ret = alq_open_flags(alqp, file, cred, cmode, size*count, 0);
497 (*alqp)->aq_flags |= AQ_LEGACY;
498 (*alqp)->aq_entmax = count;
499 (*alqp)->aq_entlen = size;
501 ret = alq_open_flags(alqp, file, cred, cmode, size, 0);
508 * Copy a new entry into the queue. If the operation would block either
509 * wait or return an error depending on the value of waitok.
512 alq_writen(struct alq *alq, void *data, int len, int flags)
514 int activate, copy, ret;
517 KASSERT((len > 0 && len <= alq->aq_buflen),
518 ("%s: len <= 0 || len > aq_buflen", __func__));
527 * Fail to perform the write and return EWOULDBLOCK if:
528 * - The message is larger than our underlying buffer.
529 * - The ALQ is being shutdown.
530 * - There is insufficient free space in our underlying buffer
531 * to accept the message and the user can't wait for space.
532 * - There is insufficient free space in our underlying buffer
533 * to accept the message and the alq is inactive due to prior
534 * use of the ALQ_NOACTIVATE flag (which would lead to deadlock).
536 if (len > alq->aq_buflen ||
537 alq->aq_flags & AQ_SHUTDOWN ||
538 (((flags & ALQ_NOWAIT) || (!(alq->aq_flags & AQ_ACTIVE) &&
539 HAS_PENDING_DATA(alq))) && alq->aq_freebytes < len)) {
541 return (EWOULDBLOCK);
545 * If we want ordered writes and there is already at least one thread
546 * waiting for resources to become available, sleep until we're woken.
548 if (alq->aq_flags & AQ_ORDERED && alq->aq_waiters > 0) {
549 KASSERT(!(flags & ALQ_NOWAIT),
550 ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__));
552 msleep_spin(&alq->aq_waiters, &alq->aq_mtx, "alqwnord", 0);
557 * (ALQ_WAITOK && aq_freebytes < len) or aq_freebytes >= len, either
558 * enter while loop and sleep until we have enough free bytes (former)
559 * or skip (latter). If AQ_ORDERED is set, only 1 thread at a time will
560 * be in this loop. Otherwise, multiple threads may be sleeping here
561 * competing for ALQ resources.
563 while (alq->aq_freebytes < len && !(alq->aq_flags & AQ_SHUTDOWN)) {
564 KASSERT(!(flags & ALQ_NOWAIT),
565 ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__));
566 alq->aq_flags |= AQ_WANTED;
570 msleep_spin(alq, &alq->aq_mtx, "alqwnres", 0);
574 * If we're the first thread to wake after an AQ_WANTED wakeup
575 * but there isn't enough free space for us, we're going to loop
576 * and sleep again. If there are other threads waiting in this
577 * loop, schedule a wakeup so that they can see if the space
578 * they require is available.
580 if (alq->aq_waiters > 0 && !(alq->aq_flags & AQ_ORDERED) &&
581 alq->aq_freebytes < len && !(alq->aq_flags & AQ_WANTED))
588 * If there are waiters, we need to signal the waiting threads after we
589 * complete our work. The alq ptr is used as a wait channel for threads
590 * requiring resources to be freed up. In the AQ_ORDERED case, threads
591 * are not allowed to concurrently compete for resources in the above
592 * while loop, so we use a different wait channel in this case.
594 if (alq->aq_waiters > 0) {
595 if (alq->aq_flags & AQ_ORDERED)
596 waitchan = &alq->aq_waiters;
602 /* Bail if we're shutting down. */
603 if (alq->aq_flags & AQ_SHUTDOWN) {
609 * If we need to wrap the buffer to accommodate the write,
610 * we'll need 2 calls to bcopy.
612 if ((alq->aq_buflen - alq->aq_writehead) < len)
613 copy = alq->aq_buflen - alq->aq_writehead;
615 /* Copy message (or part thereof if wrap required) to the buffer. */
616 bcopy(data, alq->aq_entbuf + alq->aq_writehead, copy);
617 alq->aq_writehead += copy;
619 if (alq->aq_writehead >= alq->aq_buflen) {
620 KASSERT((alq->aq_writehead == alq->aq_buflen),
621 ("%s: alq->aq_writehead (%d) > alq->aq_buflen (%d)",
625 alq->aq_writehead = 0;
630 * Wrap the buffer by copying the remainder of our message
631 * to the start of the buffer and resetting aq_writehead.
633 bcopy(((uint8_t *)data)+copy, alq->aq_entbuf, len - copy);
634 alq->aq_writehead = len - copy;
637 KASSERT((alq->aq_writehead >= 0 && alq->aq_writehead < alq->aq_buflen),
638 ("%s: aq_writehead < 0 || aq_writehead >= aq_buflen", __func__));
640 alq->aq_freebytes -= len;
642 if (!(alq->aq_flags & AQ_ACTIVE) && !(flags & ALQ_NOACTIVATE)) {
643 alq->aq_flags |= AQ_ACTIVE;
647 KASSERT((HAS_PENDING_DATA(alq)), ("%s: queue empty!", __func__));
658 /* NB: We rely on wakeup_one waking threads in a FIFO manner. */
659 if (waitchan != NULL)
660 wakeup_one(waitchan);
666 alq_write(struct alq *alq, void *data, int flags)
668 /* Should only be called in fixed length message (legacy) mode. */
669 KASSERT((alq->aq_flags & AQ_LEGACY),
670 ("%s: fixed length write on variable length queue", __func__));
671 return (alq_writen(alq, data, alq->aq_entlen, flags));
675 * Retrieve a pointer for the ALQ to write directly into, avoiding bcopy.
678 alq_getn(struct alq *alq, int len, int flags)
683 KASSERT((len > 0 && len <= alq->aq_buflen),
684 ("%s: len <= 0 || len > alq->aq_buflen", __func__));
691 * Determine the number of free contiguous bytes.
692 * We ensure elsewhere that if aq_writehead == aq_writetail because
693 * the buffer is empty, they will both be set to 0 and therefore
694 * aq_freebytes == aq_buflen and is fully contiguous.
695 * If they are equal and the buffer is not empty, aq_freebytes will
696 * be 0 indicating the buffer is full.
698 if (alq->aq_writehead <= alq->aq_writetail)
699 contigbytes = alq->aq_freebytes;
701 contigbytes = alq->aq_buflen - alq->aq_writehead;
703 if (contigbytes < len) {
705 * Insufficient space at end of buffer to handle a
706 * contiguous write. Wrap early if there's space at
707 * the beginning. This will leave a hole at the end
708 * of the buffer which we will have to skip over when
709 * flushing the buffer to disk.
711 if (alq->aq_writetail >= len || flags & ALQ_WAITOK) {
712 /* Keep track of # bytes left blank. */
713 alq->aq_wrapearly = contigbytes;
714 /* Do the wrap and adjust counters. */
715 contigbytes = alq->aq_freebytes =
717 alq->aq_writehead = 0;
723 * Return a NULL ALE if:
724 * - The message is larger than our underlying buffer.
725 * - The ALQ is being shutdown.
726 * - There is insufficient free space in our underlying buffer
727 * to accept the message and the user can't wait for space.
728 * - There is insufficient free space in our underlying buffer
729 * to accept the message and the alq is inactive due to prior
730 * use of the ALQ_NOACTIVATE flag (which would lead to deadlock).
732 if (len > alq->aq_buflen ||
733 alq->aq_flags & AQ_SHUTDOWN ||
734 (((flags & ALQ_NOWAIT) || (!(alq->aq_flags & AQ_ACTIVE) &&
735 HAS_PENDING_DATA(alq))) && contigbytes < len)) {
741 * If we want ordered writes and there is already at least one thread
742 * waiting for resources to become available, sleep until we're woken.
744 if (alq->aq_flags & AQ_ORDERED && alq->aq_waiters > 0) {
745 KASSERT(!(flags & ALQ_NOWAIT),
746 ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__));
748 msleep_spin(&alq->aq_waiters, &alq->aq_mtx, "alqgnord", 0);
753 * (ALQ_WAITOK && contigbytes < len) or contigbytes >= len, either enter
754 * while loop and sleep until we have enough contiguous free bytes
755 * (former) or skip (latter). If AQ_ORDERED is set, only 1 thread at a
756 * time will be in this loop. Otherwise, multiple threads may be
757 * sleeping here competing for ALQ resources.
759 while (contigbytes < len && !(alq->aq_flags & AQ_SHUTDOWN)) {
760 KASSERT(!(flags & ALQ_NOWAIT),
761 ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__));
762 alq->aq_flags |= AQ_WANTED;
766 msleep_spin(alq, &alq->aq_mtx, "alqgnres", 0);
769 if (alq->aq_writehead <= alq->aq_writetail)
770 contigbytes = alq->aq_freebytes;
772 contigbytes = alq->aq_buflen - alq->aq_writehead;
775 * If we're the first thread to wake after an AQ_WANTED wakeup
776 * but there isn't enough free space for us, we're going to loop
777 * and sleep again. If there are other threads waiting in this
778 * loop, schedule a wakeup so that they can see if the space
779 * they require is available.
781 if (alq->aq_waiters > 0 && !(alq->aq_flags & AQ_ORDERED) &&
782 contigbytes < len && !(alq->aq_flags & AQ_WANTED))
789 * If there are waiters, we need to signal the waiting threads after we
790 * complete our work. The alq ptr is used as a wait channel for threads
791 * requiring resources to be freed up. In the AQ_ORDERED case, threads
792 * are not allowed to concurrently compete for resources in the above
793 * while loop, so we use a different wait channel in this case.
795 if (alq->aq_waiters > 0) {
796 if (alq->aq_flags & AQ_ORDERED)
797 waitchan = &alq->aq_waiters;
803 /* Bail if we're shutting down. */
804 if (alq->aq_flags & AQ_SHUTDOWN) {
806 if (waitchan != NULL)
807 wakeup_one(waitchan);
812 * If we are here, we have a contiguous number of bytes >= len
813 * available in our buffer starting at aq_writehead.
815 alq->aq_getpost.ae_data = alq->aq_entbuf + alq->aq_writehead;
816 alq->aq_getpost.ae_bytesused = len;
818 return (&alq->aq_getpost);
822 alq_get(struct alq *alq, int flags)
824 /* Should only be called in fixed length message (legacy) mode. */
825 KASSERT((alq->aq_flags & AQ_LEGACY),
826 ("%s: fixed length get on variable length queue", __func__));
827 return (alq_getn(alq, alq->aq_entlen, flags));
831 alq_post_flags(struct alq *alq, struct ale *ale, int flags)
838 if (ale->ae_bytesused > 0) {
839 if (!(alq->aq_flags & AQ_ACTIVE) &&
840 !(flags & ALQ_NOACTIVATE)) {
841 alq->aq_flags |= AQ_ACTIVE;
845 alq->aq_writehead += ale->ae_bytesused;
846 alq->aq_freebytes -= ale->ae_bytesused;
848 /* Wrap aq_writehead if we filled to the end of the buffer. */
849 if (alq->aq_writehead == alq->aq_buflen)
850 alq->aq_writehead = 0;
852 KASSERT((alq->aq_writehead >= 0 &&
853 alq->aq_writehead < alq->aq_buflen),
854 ("%s: aq_writehead < 0 || aq_writehead >= aq_buflen",
857 KASSERT((HAS_PENDING_DATA(alq)), ("%s: queue empty!", __func__));
861 * If there are waiters, we need to signal the waiting threads after we
862 * complete our work. The alq ptr is used as a wait channel for threads
863 * requiring resources to be freed up. In the AQ_ORDERED case, threads
864 * are not allowed to concurrently compete for resources in the
865 * alq_getn() while loop, so we use a different wait channel in this case.
867 if (alq->aq_waiters > 0) {
868 if (alq->aq_flags & AQ_ORDERED)
869 waitchan = &alq->aq_waiters;
883 /* NB: We rely on wakeup_one waking threads in a FIFO manner. */
884 if (waitchan != NULL)
885 wakeup_one(waitchan);
889 alq_flush(struct alq *alq)
897 * Pull the lever iff there is data to flush and we're
898 * not already in the middle of a flush operation.
900 if (HAS_PENDING_DATA(alq) && !(alq->aq_flags & AQ_FLUSHING)) {
901 if (alq->aq_flags & AQ_ACTIVE)
905 needwakeup = alq_doio(alq);
916 * Flush remaining data, close the file and free all resources.
919 alq_close(struct alq *alq)
921 /* Only flush and destroy alq if not already shutting down. */
922 if (ald_rem(alq) == 0)
927 alq_load_handler(module_t mod, int what, void *arg)
940 /* Only allow unload if there are no open queues. */
941 if (LIST_FIRST(&ald_queues) == NULL) {
944 ald_shutdown(NULL, 0);
945 mtx_destroy(&ald_mtx);
953 /* If MOD_QUIESCE failed we must fail here too. */
954 if (ald_shutingdown == 0)
966 static moduledata_t alq_mod =
973 DECLARE_MODULE(alq, alq_mod, SI_SUB_SMP, SI_ORDER_ANY);
974 MODULE_VERSION(alq, 1);