fs: rename AT_* to VATTR_*

[unleashed/lotheac.git] / kernel / fs / fifofs / fifovnops.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All rights reserved.          */


/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright 2015, Joyent, Inc.
 * Copyright (c) 2017 by Delphix. All rights reserved.
 */

/*
 * FIFOFS file system vnode operations.  This file system
 * type supports STREAMS-based pipes and FIFOs.
 */
#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/cred.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/file.h>
#include <sys/fcntl.h>
#include <sys/kmem.h>
#include <sys/uio.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/pathname.h>
#include <sys/signal.h>
#include <sys/user.h>
#include <sys/strsubr.h>
#include <sys/stream.h>
#include <sys/strsun.h>
#include <sys/strredir.h>
#include <sys/fs/fifonode.h>
#include <sys/fs/namenode.h>
#include <sys/stropts.h>
#include <sys/proc.h>
#include <sys/unistd.h>
#include <sys/debug.h>
#include <sys/fs_subr.h>
#include <sys/filio.h>
#include <sys/termio.h>
#include <sys/ddi.h>
#include <sys/vtrace.h>
#include <sys/policy.h>

/*
 * Define the routines/data structures used in this file.
 */
static int fifo_read(vnode_t *, uio_t *, int, cred_t *, caller_context_t *);
static int fifo_write(vnode_t *, uio_t *, int, cred_t *, caller_context_t *);
static int fifo_getattr(vnode_t *, vattr_t *, int, cred_t *,
        caller_context_t *);
static int fifo_setattr(vnode_t *, vattr_t *, int, cred_t *,
        caller_context_t *);
static int fifo_realvp(vnode_t *, vnode_t **, caller_context_t *);
static int fifo_access(vnode_t *, int, int, cred_t *, caller_context_t *);
static int fifo_create(struct vnode *, char *, vattr_t *, enum vcexcl,
    int, struct vnode **, struct cred *, int, caller_context_t *,
    vsecattr_t *);
static int fifo_fid(vnode_t *, fid_t *, caller_context_t *);
static int fifo_fsync(vnode_t *, int, cred_t *, caller_context_t *);
static int fifo_seek(vnode_t *, offset_t, offset_t *, caller_context_t *);
static int fifo_ioctl(vnode_t *, int, intptr_t, int, cred_t *, int *,
        caller_context_t *);
static int fifo_fastioctl(vnode_t *, int, intptr_t, int, cred_t *, int *);
static int fifo_strioctl(vnode_t *, int, intptr_t, int, cred_t *, int *);
static int fifo_poll(vnode_t *, short, int, short *, pollhead_t **,
        caller_context_t *);
static int fifo_pathconf(vnode_t *, int, ulong_t *, cred_t *,
        caller_context_t *);
static void fifo_inactive(vnode_t *, cred_t *, caller_context_t *);
static int fifo_rwlock(vnode_t *, int, caller_context_t *);
static void fifo_rwunlock(vnode_t *, int, caller_context_t *);
static int fifo_setsecattr(struct vnode *, vsecattr_t *, int, struct cred *,
        caller_context_t *);
static int fifo_getsecattr(struct vnode *, vsecattr_t *, int, struct cred *,
        caller_context_t *);

/* functions local to this file */
static boolean_t fifo_stayfast_enter(fifonode_t *);
static void fifo_stayfast_exit(fifonode_t *);

/*
 * Define the data structures external to this file.
 */
extern  dev_t   fifodev;
extern struct qinit fifo_stwdata;
extern struct qinit fifo_strdata;
extern kmutex_t ftable_lock;

struct  streamtab fifoinfo = { &fifo_strdata, &fifo_stwdata, NULL, NULL };

const struct vnodeops fifo_vnodeops = {
        .vnop_name = "fifofs",
        .vop_open = fifo_open,
        .vop_close = fifo_close,
        .vop_read = fifo_read,
        .vop_write = fifo_write,
        .vop_ioctl = fifo_ioctl,
        .vop_getattr = fifo_getattr,
        .vop_setattr = fifo_setattr,
        .vop_access = fifo_access,
        .vop_create = fifo_create,
        .vop_fsync = fifo_fsync,
        .vop_inactive = fifo_inactive,
        .vop_fid = fifo_fid,
        .vop_rwlock = fifo_rwlock,
        .vop_rwunlock = fifo_rwunlock,
        .vop_seek = fifo_seek,
        .vop_realvp = fifo_realvp,
        .vop_poll = fifo_poll,
        .vop_pathconf = fifo_pathconf,
        .vop_dispose = fs_nodispose,
        .vop_setsecattr = fifo_setsecattr,
        .vop_getsecattr = fifo_getsecattr,
};

/*
 * Return the fifoinfo structure.
 */
struct streamtab *
fifo_getinfo()
{
        return (&fifoinfo);
}

/*
 * Open and stream a FIFO.
 * If this is the first open of the file (FIFO is not streaming),
 * initialize the fifonode and attach a stream to the vnode.
 *
 * Each end of a fifo must be synchronized with the other end.
 * If not, the mated end may complete an open, I/O, close sequence
 * before the end waiting in open ever wakes up.
 * Note: namefs pipes come through this routine too.
 */
int
fifo_open(vnode_t **vpp, int flag, cred_t *crp, caller_context_t *ct)
{
        vnode_t         *vp             = *vpp;
        fifonode_t      *fnp            = VTOF(vp);
        fifolock_t      *fn_lock        = fnp->fn_lock;
        int             error;

        ASSERT(vp->v_type == VFIFO);
        ASSERT(vn_matchops(vp, &fifo_vnodeops));

        mutex_enter(&fn_lock->flk_lock);
        /*
         * If we are the first reader, wake up any writers that
         * may be waiting around.  wait for all of them to
         * wake up before proceeding (i.e. fn_wsynccnt == 0)
         */
        if (flag & FREAD) {
                fnp->fn_rcnt++;         /* record reader present */
                if (! (fnp->fn_flag & ISPIPE))
                        fnp->fn_rsynccnt++;     /* record reader in open */
        }

        /*
         * If we are the first writer, wake up any readers that
         * may be waiting around.  wait for all of them to
         * wake up before proceeding (i.e. fn_rsynccnt == 0)
         */
        if (flag & FWRITE) {
                fnp->fn_wcnt++;         /* record writer present */
                if (! (fnp->fn_flag & ISPIPE))
                        fnp->fn_wsynccnt++;     /* record writer in open */
        }
        /*
         * fifo_stropen will take care of twisting the queues on the first
         * open.  The 1 being passed in means twist the queues on the first
         * open.
         */
        error = fifo_stropen(vpp, flag, crp, 1, 1);
        /*
         * fifo_stropen() could have replaced vpp
         * since fifo's are the only thing we need to sync up,
         * everything else just returns;
         * Note: don't need to hold lock since ISPIPE can't change
         * and both old and new vp need to be pipes
         */
        ASSERT(MUTEX_HELD(&VTOF(*vpp)->fn_lock->flk_lock));
        if (fnp->fn_flag & ISPIPE) {
                ASSERT(VTOF(*vpp)->fn_flag & ISPIPE);
                ASSERT(VTOF(*vpp)->fn_rsynccnt == 0);
                ASSERT(VTOF(*vpp)->fn_rsynccnt == 0);
                /*
                 * XXX note: should probably hold locks, but
                 * These values should not be changing
                 */
                ASSERT(fnp->fn_rsynccnt == 0);
                ASSERT(fnp->fn_wsynccnt == 0);
                mutex_exit(&VTOF(*vpp)->fn_lock->flk_lock);
                return (error);
        }
        /*
         * vp can't change for FIFOS
         */
        ASSERT(vp == *vpp);
        /*
         * If we are opening for read (or writer)
         *   indicate that the reader (or writer) is done with open
         *   if there is a writer (or reader) waiting for us, wake them up
         *      and indicate that at least 1 read (or write) open has occurred
         *      this is need in the event the read (or write) side closes
         *      before the writer (or reader) has a chance to wake up
         *      i.e. it sees that a reader (or writer) was once there
         */
        if (flag & FREAD) {
                fnp->fn_rsynccnt--;     /* reader done with open */
                if (fnp->fn_flag & FIFOSYNC) {
                        /*
                         * This indicates that a read open has occurred
                         * Only need to set if writer is actually asleep
                         * Flag will be consumed by writer.
                         */
                        fnp->fn_flag |= FIFOROCR;
                        cv_broadcast(&fnp->fn_wait_cv);
                }
        }
        if (flag & FWRITE) {
                fnp->fn_wsynccnt--;     /* writer done with open */
                if (fnp->fn_flag & FIFOSYNC) {
                        /*
                         * This indicates that a write open has occurred
                         * Only need to set if reader is actually asleep
                         * Flag will be consumed by reader.
                         */
                        fnp->fn_flag |= FIFOWOCR;
                        cv_broadcast(&fnp->fn_wait_cv);
                }
        }

        fnp->fn_flag &= ~FIFOSYNC;

        /*
         * errors don't wait around.. just return
         * Note: XXX other end will wake up and continue despite error.
         * There is no defined semantic on the correct course of option
         * so we do what we've done in the past
         */
        if (error != 0) {
                mutex_exit(&fnp->fn_lock->flk_lock);
                goto done;
        }
        ASSERT(fnp->fn_rsynccnt <= fnp->fn_rcnt);
        ASSERT(fnp->fn_wsynccnt <= fnp->fn_wcnt);
        /*
         * FIFOWOCR (or FIFOROCR) indicates that the writer (or reader)
         * has woken us up and is done with open (this way, if the other
         * end has made it to close, we don't block forever in open)
         * fn_wnct == fn_wsynccnt (or fn_rcnt == fn_rsynccnt) indicates
         * that no writer (or reader) has yet made it through open
         * This has the side benefit of that the first
         * reader (or writer) will wait until the other end finishes open
         */
        if (flag & FREAD) {
                while ((fnp->fn_flag & FIFOWOCR) == 0 &&
                    fnp->fn_wcnt == fnp->fn_wsynccnt) {
                        if (flag & (FNDELAY|FNONBLOCK)) {
                                mutex_exit(&fnp->fn_lock->flk_lock);
                                goto done;
                        }
                        fnp->fn_insync++;
                        fnp->fn_flag |= FIFOSYNC;
                        if (!cv_wait_sig_swap(&fnp->fn_wait_cv,
                            &fnp->fn_lock->flk_lock)) {
                                /*
                                 * Last reader to wakeup clear writer
                                 * Clear both writer and reader open
                                 * occurred flag incase other end is O_RDWR
                                 */
                                if (--fnp->fn_insync == 0 &&
                                    fnp->fn_flag & FIFOWOCR) {
                                        fnp->fn_flag &= ~(FIFOWOCR|FIFOROCR);
                                }
                                mutex_exit(&fnp->fn_lock->flk_lock);
                                (void) fifo_close(*vpp, flag, 1, 0, crp, ct);
                                error = EINTR;
                                goto done;
                        }
                        /*
                         * Last reader to wakeup clear writer open occurred flag
                         * Clear both writer and reader open occurred flag
                         * incase other end is O_RDWR
                         */
                        if (--fnp->fn_insync == 0 &&
                            fnp->fn_flag & FIFOWOCR) {
                                fnp->fn_flag &= ~(FIFOWOCR|FIFOROCR);
                                break;
                        }
                }
        } else if (flag & FWRITE) {
                while ((fnp->fn_flag & FIFOROCR) == 0 &&
                    fnp->fn_rcnt == fnp->fn_rsynccnt) {
                        if ((flag & (FNDELAY|FNONBLOCK)) && fnp->fn_rcnt == 0) {
                                mutex_exit(&fnp->fn_lock->flk_lock);
                                (void) fifo_close(*vpp, flag, 1, 0, crp, ct);
                                error = ENXIO;
                                goto done;
                        }
                        fnp->fn_flag |= FIFOSYNC;
                        fnp->fn_insync++;
                        if (!cv_wait_sig_swap(&fnp->fn_wait_cv,
                            &fnp->fn_lock->flk_lock)) {
                                /*
                                 * Last writer to wakeup clear
                                 * Clear both writer and reader open
                                 * occurred flag in case other end is O_RDWR
                                 */
                                if (--fnp->fn_insync == 0 &&
                                    (fnp->fn_flag & FIFOROCR) != 0) {
                                        fnp->fn_flag &= ~(FIFOWOCR|FIFOROCR);
                                }
                                mutex_exit(&fnp->fn_lock->flk_lock);
                                (void) fifo_close(*vpp, flag, 1, 0, crp, ct);
                                error = EINTR;
                                goto done;
                        }
                        /*
                         * Last writer to wakeup clear reader open occurred flag
                         * Clear both writer and reader open
                         * occurred flag in case other end is O_RDWR
                         */
                        if (--fnp->fn_insync == 0 &&
                            (fnp->fn_flag & FIFOROCR) != 0) {
                                fnp->fn_flag &= ~(FIFOWOCR|FIFOROCR);
                                break;
                        }
                }
        }
        mutex_exit(&fn_lock->flk_lock);
done:
        return (error);
}

/*
 * Close down a stream.
 * Call cleanlocks() and strclean() on every close.
 * For last close send hangup message and force
 * the other end of a named pipe to be unmounted.
 * Mount guarantees that the mounted end will only call fifo_close()
 * with a count of 1 when the unmount occurs.
 * This routine will close down one end of a pipe or FIFO
 * and free the stream head via strclose()
 */
/*ARGSUSED*/
int
fifo_close(vnode_t *vp, int flag, int count, offset_t offset, cred_t *crp,
    caller_context_t *ct)
{
        fifonode_t      *fnp            = VTOF(vp);
        fifonode_t      *fn_dest        = fnp->fn_dest;
        int             error           = 0;
        fifolock_t      *fn_lock        = fnp->fn_lock;
        queue_t         *sd_wrq;
        vnode_t         *fn_dest_vp;
        int             senthang = 0;

        ASSERT(vp->v_stream != NULL);
        /*
         * clean locks and clear events.
         */
        (void) cleanlocks(vp, ttoproc(curthread)->p_pid, 0);
        cleanshares(vp, ttoproc(curthread)->p_pid);
        strclean(vp);

        /*
         * If a file still has the pipe/FIFO open, return.
         */
        if (count > 1)
                return (0);


        sd_wrq = strvp2wq(vp);
        mutex_enter(&fn_lock->flk_lock);

        /*
         * wait for pending opens to finish up
         * note: this also has the side effect of single threading closes
         */
        while (fn_lock->flk_ocsync)
                cv_wait(&fn_lock->flk_wait_cv, &fn_lock->flk_lock);

        fn_lock->flk_ocsync = 1;

        if (flag & FREAD) {
                fnp->fn_rcnt--;
        }
        /*
         * If we are last writer wake up sleeping readers
         * (They'll figure out that there are no more writers
         * and do the right thing)
         * send hangup down stream so that stream head will do the
         * right thing.
         */
        if (flag & FWRITE) {
                if (--fnp->fn_wcnt == 0 && fn_dest->fn_rcnt > 0) {
                        if ((fn_dest->fn_flag & (FIFOFAST | FIFOWANTR)) ==
                            (FIFOFAST | FIFOWANTR)) {
                                /*
                                 * While we're at it, clear FIFOWANTW too
                                 * Wake up any sleeping readers or
                                 * writers.
                                 */
                                fn_dest->fn_flag &= ~(FIFOWANTR | FIFOWANTW);
                                cv_broadcast(&fn_dest->fn_wait_cv);
                        }
                        /*
                         * This is needed incase the other side
                         * was opened non-blocking.  It is the
                         * only way we can tell that wcnt is 0 because
                         * of close instead of never having a writer
                         */
                        if (!(fnp->fn_flag & ISPIPE))
                                fnp->fn_flag |= FIFOCLOSE;
                        /*
                         * Note: sending hangup effectively shuts down
                         * both reader and writer at other end.
                         */
                        (void) putnextctl_wait(sd_wrq, M_HANGUP);
                        senthang = 1;
                }
        }

        /*
         * For FIFOs we need to indicate to stream head that last reader
         * has gone away so that an error is generated
         * Pipes just need to wake up the other end so that it can
         * notice this end has gone away.
         */

        if (fnp->fn_rcnt == 0 && fn_dest->fn_wcnt > 0) {
                if ((fn_dest->fn_flag & (FIFOFAST | FIFOWANTW)) ==
                    (FIFOFAST | FIFOWANTW)) {
                        /*
                         * wake up any sleeping writers
                         */
                        fn_dest->fn_flag &= ~FIFOWANTW;
                        cv_broadcast(&fn_dest->fn_wait_cv);
                }
        }

        /*
         * if there are still processes with this FIFO open
         *      clear open/close sync flag
         *      and just return;
         */
        if (--fnp->fn_open > 0) {
                ASSERT((fnp->fn_rcnt + fnp->fn_wcnt) != 0);
                fn_lock->flk_ocsync = 0;
                cv_broadcast(&fn_lock->flk_wait_cv);
                mutex_exit(&fn_lock->flk_lock);
                return (0);
        }

        /*
         * Need to send HANGUP if other side is still open
         * (fnp->fn_rcnt or fnp->fn_wcnt may not be zero (some thread
         * on this end of the pipe may still be in fifo_open())
         *
         * Note: we can get here with fn_rcnt and fn_wcnt != 0 if some
         * thread is blocked somewhere in the fifo_open() path prior to
         * fifo_stropen() incrementing fn_open.  This can occur for
         * normal FIFOs as well as named pipes.  fn_rcnt and
         * fn_wcnt only indicate attempts to open. fn_open indicates
         * successful opens. Partially opened FIFOs should proceed
         * normally; i.e. they will appear to be new opens.  Partially
         * opened pipes will probably fail.
         */

        if (fn_dest->fn_open && senthang == 0)
                (void) putnextctl_wait(sd_wrq, M_HANGUP);


        /*
         * If this a pipe and this is the first end to close,
         * then we have a bit of cleanup work to do.
         *      Mark both ends of pipe as closed.
         *      Wake up anybody blocked at the other end and for named pipes,
         *      Close down this end of the stream
         *      Allow other opens/closes to continue
         *      force an unmount of other end.
         * Otherwise if this is last close,
         *      flush messages,
         *      close down the stream
         *      allow other opens/closes to continue
         */
        fnp->fn_flag &= ~FIFOISOPEN;
        if ((fnp->fn_flag & ISPIPE) && !(fnp->fn_flag & FIFOCLOSE)) {
                fnp->fn_flag |= FIFOCLOSE;
                fn_dest->fn_flag |= FIFOCLOSE;
                if (fnp->fn_flag & FIFOFAST)
                        fifo_fastflush(fnp);
                if (vp->v_stream != NULL) {
                        mutex_exit(&fn_lock->flk_lock);
                        (void) strclose(vp, flag, crp);
                        mutex_enter(&fn_lock->flk_lock);
                }
                cv_broadcast(&fn_dest->fn_wait_cv);
                /*
                 * allow opens and closes to proceed
                 * Since this end is now closed down, any attempt
                 * to do anything with this end will fail
                 */
                fn_lock->flk_ocsync = 0;
                cv_broadcast(&fn_lock->flk_wait_cv);
                fn_dest_vp = FTOV(fn_dest);
                /*
                 * if other end of pipe has been opened and it's
                 * a named pipe, unmount it
                 */
                if (fn_dest_vp->v_stream &&
                    (fn_dest_vp->v_stream->sd_flag & STRMOUNT)) {
                        /*
                         * We must hold the destination vnode because
                         * nm_unmountall() causes close to be called
                         * for the other end of named pipe.  This
                         * could free the vnode before we are ready.
                         */
                        VN_HOLD(fn_dest_vp);
                        mutex_exit(&fn_lock->flk_lock);
                        error = nm_unmountall(fn_dest_vp, crp);
                        ASSERT(error == 0);
                        VN_RELE(fn_dest_vp);
                } else {
                        ASSERT(vp->v_count >= 1);
                        mutex_exit(&fn_lock->flk_lock);
                }
        } else {
                if (fnp->fn_flag & FIFOFAST)
                        fifo_fastflush(fnp);
#if DEBUG
                fn_dest_vp = FTOV(fn_dest);
                if (fn_dest_vp->v_stream)
                        ASSERT((fn_dest_vp->v_stream->sd_flag & STRMOUNT) == 0);
#endif
                if (vp->v_stream != NULL) {
                        mutex_exit(&fn_lock->flk_lock);
                        (void) strclose(vp, flag, crp);
                        mutex_enter(&fn_lock->flk_lock);
                }
                fn_lock->flk_ocsync = 0;
                cv_broadcast(&fn_lock->flk_wait_cv);
                cv_broadcast(&fn_dest->fn_wait_cv);
                mutex_exit(&fn_lock->flk_lock);
        }
        return (error);
}

/*
 * Read from a pipe or FIFO.
 * return 0 if....
 *    (1) user read request is 0 or no stream
 *    (2) broken pipe with no data
 *    (3) write-only FIFO with no data
 *    (4) no data and FNDELAY flag is set.
 * Otherwise return
 *      EAGAIN if FNONBLOCK is set and no data to read
 *      EINTR if signal received while waiting for data
 *
 * While there is no data to read....
 *   -  if the NDELAY/NONBLOCK flag is set, return 0/EAGAIN.
 *   -  wait for a write.
 *
 */
/*ARGSUSED*/

static int
fifo_read(struct vnode *vp, struct uio *uiop, int ioflag, struct cred *crp,
    caller_context_t *ct)
{
        fifonode_t      *fnp            = VTOF(vp);
        fifonode_t      *fn_dest;
        fifolock_t      *fn_lock        = fnp->fn_lock;
        int             error           = 0;
        mblk_t          *bp;

        ASSERT(vp->v_stream != NULL);
        if (uiop->uio_resid == 0)
                return (0);

        mutex_enter(&fn_lock->flk_lock);

        TRACE_2(TR_FAC_FIFO, TR_FIFOREAD_IN, "fifo_read in:%p fnp %p", vp, fnp);

        if (! (fnp->fn_flag & FIFOFAST))
                goto stream_mode;

        fn_dest = fnp->fn_dest;
        /*
         * Check for data on our input queue
         */

        while (fnp->fn_count == 0) {
                /*
                 * No data on first attempt and no writer, then EOF
                 */
                if (fn_dest->fn_wcnt == 0 || fn_dest->fn_rcnt == 0) {
                        mutex_exit(&fn_lock->flk_lock);
                        return (0);
                }
                /*
                 * no data found.. if non-blocking, return EAGAIN
                 * otherwise 0.
                 */
                if (uiop->uio_fmode & (FNDELAY|FNONBLOCK)) {
                        mutex_exit(&fn_lock->flk_lock);
                        if (uiop->uio_fmode & FNONBLOCK)
                                return (EAGAIN);
                        return (0);
                }

                /*
                 * Note: FIFOs can get here with FIFOCLOSE set if
                 * write side is in the middle of opeining after
                 * it once closed. Pipes better not have FIFOCLOSE set
                 */
                ASSERT((fnp->fn_flag & (ISPIPE|FIFOCLOSE)) !=
                    (ISPIPE|FIFOCLOSE));
                /*
                 * wait for data
                 */
                fnp->fn_flag |= FIFOWANTR;

                TRACE_1(TR_FAC_FIFO, TR_FIFOREAD_WAIT, "fiforead wait: %p", vp);

                if (!cv_wait_sig_swap(&fnp->fn_wait_cv,
                    &fn_lock->flk_lock)) {
                        error = EINTR;
                        goto done;
                }

                TRACE_1(TR_FAC_FIFO, TR_FIFOREAD_WAKE,
                    "fiforead awake: %p", vp);

                /*
                 * check to make sure we are still in fast mode
                 */
                if (!(fnp->fn_flag & FIFOFAST))
                        goto stream_mode;
        }

        ASSERT(fnp->fn_mp != NULL);

        /* For pipes copy should not bypass cache */
        uiop->uio_extflg |= UIO_COPY_CACHED;

        do {
                int bpsize = MBLKL(fnp->fn_mp);
                int uiosize = MIN(bpsize, uiop->uio_resid);

                error = uiomove(fnp->fn_mp->b_rptr, uiosize, UIO_READ, uiop);
                if (error != 0)
                        break;

                fnp->fn_count -= uiosize;

                if (bpsize <= uiosize) {
                        bp = fnp->fn_mp;
                        fnp->fn_mp = fnp->fn_mp->b_cont;
                        freeb(bp);

                        if (uiop->uio_resid == 0)
                                break;

                        while (fnp->fn_mp == NULL && fn_dest->fn_wwaitcnt > 0) {
                                ASSERT(fnp->fn_count == 0);

                                if (uiop->uio_fmode & (FNDELAY|FNONBLOCK))
                                        goto trywake;

                                /*
                                 * We've consumed all available data but there
                                 * are threads waiting to write more, let them
                                 * proceed before bailing.
                                 */

                                fnp->fn_flag |= FIFOWANTR;
                                fifo_wakewriter(fn_dest, fn_lock);

                                if (!cv_wait_sig(&fnp->fn_wait_cv,
                                    &fn_lock->flk_lock))
                                        goto trywake;

                                if (!(fnp->fn_flag & FIFOFAST))
                                        goto stream_mode;
                        }
                } else {
                        fnp->fn_mp->b_rptr += uiosize;
                        ASSERT(uiop->uio_resid == 0);
                }
        } while (uiop->uio_resid != 0 && fnp->fn_mp != NULL);

trywake:
        ASSERT(msgdsize(fnp->fn_mp) == fnp->fn_count);

        /*
         * wake up any blocked writers, processes
         * sleeping on POLLWRNORM, or processes waiting for SIGPOLL
         * Note: checking for fn_count < Fifohiwat emulates
         * STREAMS functionality when low water mark is 0
         */
        if (fn_dest->fn_flag & (FIFOWANTW | FIFOHIWATW) &&
            fnp->fn_count < Fifohiwat) {
                fifo_wakewriter(fn_dest, fn_lock);
        }
        goto done;

        /*
         * FIFO is in streams mode.. let the stream head handle it
         */
stream_mode:

        mutex_exit(&fn_lock->flk_lock);
        TRACE_1(TR_FAC_FIFO,
            TR_FIFOREAD_STREAM, "fifo_read stream_mode:%p", vp);

        error = strread(vp, uiop, crp);

        mutex_enter(&fn_lock->flk_lock);

done:
        /*
         * vnode update access time
         */
        if (error == 0) {
                time_t now = gethrestime_sec();

                if (fnp->fn_flag & ISPIPE)
                        fnp->fn_dest->fn_atime = now;
                fnp->fn_atime = now;
        }
        TRACE_2(TR_FAC_FIFO, TR_FIFOREAD_OUT,
            "fifo_read out:%p error %d", vp, error);
        mutex_exit(&fn_lock->flk_lock);
        return (error);
}

/*
 * send SIGPIPE and return EPIPE if ...
 *   (1) broken pipe (essentially, reader is gone)
 *   (2) FIFO is not open for reading
 * return 0 if...
 *   (1) no stream
 *   (2) user write request is for 0 bytes and SW_SNDZERO is not set
 *      Note: SW_SNDZERO can't be set in fast mode
 * While the stream is flow controlled....
 *   -  if the NDELAY/NONBLOCK flag is set, return 0/EAGAIN.
 *   -  unlock the fifonode and sleep waiting for a reader.
 *   -  if a pipe and it has a mate, sleep waiting for its mate
 *      to read.
 */
/*ARGSUSED*/
static int
fifo_write(vnode_t *vp, uio_t *uiop, int ioflag, cred_t *crp,
    caller_context_t *ct)
{
        struct fifonode *fnp, *fn_dest;
        fifolock_t      *fn_lock;
        struct stdata   *stp;
        int             error   = 0;
        int             write_size;
        int             size;
        int             fmode;
        mblk_t          *bp;
        boolean_t       hotread;

        ASSERT(vp->v_stream);
        uiop->uio_loffset = 0;
        stp     = vp->v_stream;

        /*
         * remember original number of bytes requested. Used to determine if
         * we actually have written anything at all
         */
        write_size = uiop->uio_resid;

        /*
         * only send zero-length messages if SW_SNDZERO is set
         * Note: we will be in streams mode if SW_SNDZERO is set
         * XXX this streams interface should not be exposed
         */
        if ((write_size == 0) && !(stp->sd_wput_opt & SW_SNDZERO))
                return (0);

        fnp = VTOF(vp);
        fn_lock = fnp->fn_lock;
        fn_dest = fnp->fn_dest;

        mutex_enter(&fn_lock->flk_lock);

        TRACE_3(TR_FAC_FIFO, TR_FIFOWRITE_IN,
            "fifo_write in:%p fnp %p size %d", vp, fnp, write_size);

        /*
         * oops, no readers, error
         */
        if (fn_dest->fn_rcnt == 0 || fn_dest->fn_wcnt == 0) {
                goto epipe;
        }

        /*
         * if we are not in fast mode, let streams handle it
         */
        if (!(fnp->fn_flag & FIFOFAST))
                goto stream_mode;

        fmode = uiop->uio_fmode & (FNDELAY|FNONBLOCK);

        /* For pipes copy should not bypass cache */
        uiop->uio_extflg |= UIO_COPY_CACHED;

        do  {
                /*
                 * check to make sure we are not over high water mark
                 */
                while (fn_dest->fn_count >= Fifohiwat) {
                        /*
                         * Indicate that we have gone over high
                         * water mark
                         */
                        /*
                         * if non-blocking, return
                         * only happens first time through loop
                         */
                        if (fmode) {
                                fnp->fn_flag |= FIFOHIWATW;
                                if (uiop->uio_resid == write_size) {
                                        mutex_exit(&fn_lock->flk_lock);
                                        if (fmode & FNDELAY)
                                                return (0);
                                        else
                                                return (EAGAIN);
                                }
                                goto done;
                        }

                        /*
                         * wait for things to drain
                         */
                        fnp->fn_flag |= FIFOWANTW;
                        fnp->fn_wwaitcnt++;
                        TRACE_1(TR_FAC_FIFO, TR_FIFOWRITE_WAIT,
                            "fifo_write wait: %p", vp);
                        if (!cv_wait_sig_swap(&fnp->fn_wait_cv,
                            &fn_lock->flk_lock)) {
                                error = EINTR;
                                fnp->fn_wwaitcnt--;
                                fifo_wakereader(fn_dest, fn_lock);
                                goto done;
                        }
                        fnp->fn_wwaitcnt--;

                        TRACE_1(TR_FAC_FIFO, TR_FIFOWRITE_WAKE,
                            "fifo_write wake: %p", vp);

                        /*
                         * check to make sure we're still in fast mode
                         */
                        if (!(fnp->fn_flag & FIFOFAST))
                                goto stream_mode;

                        /*
                         * make sure readers didn't go away
                         */
                        if (fn_dest->fn_rcnt == 0 || fn_dest->fn_wcnt == 0) {
                                goto epipe;
                        }
                }
                /*
                 * If the write will put us over the high water mark,
                 * then we must break the message up into PIPE_BUF
                 * chunks to stay compliant with STREAMS
                 */
                if (uiop->uio_resid + fn_dest->fn_count > Fifohiwat)
                        size = MIN(uiop->uio_resid, PIPE_BUF);
                else
                        size = uiop->uio_resid;

                /*
                 * We don't need to hold flk_lock across the allocb() and
                 * uiomove().  However, on a multiprocessor machine where both
                 * the reader and writer thread are on cpu's, we must be
                 * careful to only drop the lock if there's data to be read.
                 * This forces threads entering fifo_read() to spin or block
                 * on flk_lock, rather than acquiring flk_lock only to
                 * discover there's no data to read and being forced to go
                 * back to sleep, only to be woken up microseconds later by
                 * this writer thread.
                 */
                hotread = fn_dest->fn_count > 0;
                if (hotread) {
                        if (!fifo_stayfast_enter(fnp))
                                goto stream_mode;
                        mutex_exit(&fn_lock->flk_lock);
                }

                ASSERT(size != 0);
                /*
                 * Align the mblk with the user data so that
                 * copying in the data can take advantage of
                 * the double word alignment
                 */
                if ((bp = allocb(size + 8, BPRI_MED)) == NULL) {
                        if (!hotread)
                                mutex_exit(&fn_lock->flk_lock);

                        error = strwaitbuf(size, BPRI_MED);

                        mutex_enter(&fn_lock->flk_lock);

                        if (hotread) {
                                /*
                                 * As we dropped the mutex for a moment, we
                                 * need to wake up any thread waiting to be
                                 * allowed to go from fast mode to stream mode.
                                 */
                                fifo_stayfast_exit(fnp);
                        }
                        if (error != 0) {
                                goto done;
                        }
                        /*
                         * check to make sure we're still in fast mode
                         */
                        if (!(fnp->fn_flag & FIFOFAST))
                                goto stream_mode;

                        /*
                         * make sure readers didn't go away
                         */
                        if (fn_dest->fn_rcnt == 0 || fn_dest->fn_wcnt == 0) {
                                goto epipe;
                        }
                        /*
                         * some other thread could have gotten in
                         * need to go back and check hi water mark
                         */
                        continue;
                }
                bp->b_rptr += ((uintptr_t)uiop->uio_iov->iov_base & 0x7);
                bp->b_wptr = bp->b_rptr + size;
                error = uiomove((caddr_t)bp->b_rptr, size, UIO_WRITE, uiop);
                if (hotread) {
                        mutex_enter(&fn_lock->flk_lock);
                        /*
                         * As we dropped the mutex for a moment, we need to:
                         * - wake up any thread waiting to be allowed to go
                         *   from fast mode to stream mode,
                         * - make sure readers didn't go away.
                         */
                        fifo_stayfast_exit(fnp);
                        if (fn_dest->fn_rcnt == 0 || fn_dest->fn_wcnt == 0) {
                                freeb(bp);
                                goto epipe;
                        }
                }

                if (error != 0) {
                        freeb(bp);
                        goto done;
                }

                fn_dest->fn_count += size;
                if (fn_dest->fn_mp != NULL) {
                        fn_dest->fn_tail->b_cont = bp;
                        fn_dest->fn_tail = bp;
                } else {
                        fn_dest->fn_mp = fn_dest->fn_tail = bp;
                        /*
                         * This is the first bit of data; wake up any sleeping
                         * readers, processes blocked in poll, and those
                         * expecting a SIGPOLL.
                         */
                        fifo_wakereader(fn_dest, fn_lock);
                }
        } while (uiop->uio_resid != 0);

        goto done;

stream_mode:
        /*
         * streams mode
         *  let the stream head handle the write
         */
        ASSERT(MUTEX_HELD(&fn_lock->flk_lock));

        mutex_exit(&fn_lock->flk_lock);
        TRACE_1(TR_FAC_FIFO,
            TR_FIFOWRITE_STREAM, "fifo_write stream_mode:%p", vp);

        error = strwrite(vp, uiop, crp);

        mutex_enter(&fn_lock->flk_lock);

done:
        /*
         * update vnode modification and change times
         * make sure there were no errors and some data was transferred
         */
        if (error == 0 && write_size != uiop->uio_resid) {
                time_t now = gethrestime_sec();

                if (fnp->fn_flag & ISPIPE) {
                        fn_dest->fn_mtime = fn_dest->fn_ctime = now;
                }
                fnp->fn_mtime = fnp->fn_ctime = now;
        } else if (fn_dest->fn_rcnt == 0 || fn_dest->fn_wcnt == 0) {
                goto epipe;
        }
        TRACE_3(TR_FAC_FIFO, TR_FIFOWRITE_OUT,
            "fifo_write out: vp %p error %d fnp %p", vp, error, fnp);
        mutex_exit(&fn_lock->flk_lock);
        return (error);
epipe:
        error = EPIPE;
        TRACE_3(TR_FAC_FIFO, TR_FIFOWRITE_OUT,
            "fifo_write out: vp %p error %d fnp %p", vp, error, fnp);
        mutex_exit(&fn_lock->flk_lock);
        tsignal(curthread, SIGPIPE);
        return (error);
}

/*ARGSUSED6*/
static int
fifo_ioctl(vnode_t *vp, int cmd, intptr_t arg, int mode, cred_t *cr,
    int *rvalp, caller_context_t *ct)
{
        /*
         * Just a quick check
         * Once we go to streams mode we don't ever revert back
         * So we do this quick check so as not to incur the overhead
         * associated with acquiring the lock
         */
        return ((VTOF(vp)->fn_flag & FIFOFAST) ?
            fifo_fastioctl(vp, cmd, arg, mode, cr, rvalp) :
            fifo_strioctl(vp, cmd, arg, mode, cr, rvalp));
}

static inline int
fifo_ioctl_getpeercred(fifonode_t *fnp, intptr_t arg, int mode)
{
        k_peercred_t *kp = (k_peercred_t *)arg;

        if (mode == FKIOCTL && fnp->fn_pcredp != NULL) {
                crhold(fnp->fn_pcredp);
                kp->pc_cr = fnp->fn_pcredp;
                kp->pc_cpid = fnp->fn_cpid;
                return (0);
        } else {
                return (ENOTSUP);
        }
}

static int
fifo_fastioctl(vnode_t *vp, int cmd, intptr_t arg, int mode, cred_t *cr,
    int *rvalp)
{
        fifonode_t      *fnp            = VTOF(vp);
        fifonode_t      *fn_dest;
        int             error           = 0;
        fifolock_t      *fn_lock        = fnp->fn_lock;
        int             cnt;

        /*
         * tty operations not allowed
         */
        if (((cmd & IOCTYPE) == LDIOC) ||
            ((cmd & IOCTYPE) == tIOC) ||
            ((cmd & IOCTYPE) == TIOC)) {
                return (EINVAL);
        }

        mutex_enter(&fn_lock->flk_lock);

        if (!(fnp->fn_flag & FIFOFAST)) {
                goto stream_mode;
        }

        switch (cmd) {

        /*
         * Things we can't handle
         * These will switch us to streams mode.
         */
        default:
        case I_STR:
        case I_SRDOPT:
        case I_PUSH:
        case I_FDINSERT:
        case I_SENDFD:
        case I_RECVFD:
        case I_E_RECVFD:
        case I_ATMARK:
        case I_CKBAND:
        case I_GETBAND:
        case I_SWROPT:
                goto turn_fastoff;

        /*
         * Things that don't do damage
         * These things don't adjust the state of the
         * stream head (i_setcltime does, but we don't care)
         */
        case I_FIND:
        case I_GETSIG:
        case FIONBIO:
        case FIOASYNC:
        case I_GRDOPT:  /* probably should not get this, but no harm */
        case I_GWROPT:
        case I_LIST:
        case I_SETCLTIME:
        case I_GETCLTIME:
                mutex_exit(&fn_lock->flk_lock);
                return (strioctl(vp, cmd, arg, mode, U_TO_K, cr, rvalp));

        case I_CANPUT:
                /*
                 * We can only handle normal band canputs.
                 * XXX : We could just always go to stream mode; after all
                 * canput is a streams semantics type thing
                 */
                if (arg != 0) {
                        goto turn_fastoff;
                }
                *rvalp = (fnp->fn_dest->fn_count < Fifohiwat) ? 1 : 0;
                mutex_exit(&fn_lock->flk_lock);
                return (0);

        case I_NREAD:
                /*
                 * This may seem a bit silly for non-streams semantics,
                 * (After all, if they really want a message, they'll
                 * probably use getmsg() anyway). but it doesn't hurt
                 */
                error = copyout((caddr_t)&fnp->fn_count, (caddr_t)arg,
                    sizeof (cnt));
                if (error == 0) {
                        *rvalp = (fnp->fn_count == 0) ? 0 : 1;
                }
                break;

        case FIORDCHK:
                *rvalp = fnp->fn_count;
                break;

        case I_PEEK:
        {
                STRUCT_DECL(strpeek, strpeek);
                struct uio      uio;
                struct iovec    iov;
                int             count;
                mblk_t          *bp;
                int             len;

                STRUCT_INIT(strpeek, mode);

                if (fnp->fn_count == 0) {
                        *rvalp = 0;
                        break;
                }

                error = copyin((caddr_t)arg, STRUCT_BUF(strpeek),
                    STRUCT_SIZE(strpeek));
                if (error)
                        break;

                /*
                 * can't have any high priority message when in fast mode
                 */
                if (STRUCT_FGET(strpeek, flags) & RS_HIPRI) {
                        *rvalp = 0;
                        break;
                }

                len = STRUCT_FGET(strpeek, databuf.maxlen);
                if (len <= 0) {
                        STRUCT_FSET(strpeek, databuf.len, len);
                } else {
                        iov.iov_base = STRUCT_FGETP(strpeek, databuf.buf);
                        iov.iov_len = len;
                        uio.uio_iov = &iov;
                        uio.uio_iovcnt = 1;
                        uio.uio_loffset = 0;
                        uio.uio_segflg = UIO_USERSPACE;
                        uio.uio_fmode = 0;
                        /* For pipes copy should not bypass cache */
                        uio.uio_extflg = UIO_COPY_CACHED;
                        uio.uio_resid = iov.iov_len;
                        count = fnp->fn_count;
                        bp = fnp->fn_mp;
                        while (count > 0 && uio.uio_resid) {
                                cnt = MIN(uio.uio_resid, MBLKL(bp));
                                if ((error = uiomove((char *)bp->b_rptr, cnt,
                                    UIO_READ, &uio)) != 0) {
                                        break;
                                }
                                count -= cnt;
                                bp = bp->b_cont;
                        }
                        STRUCT_FSET(strpeek, databuf.len, len - uio.uio_resid);
                }
                STRUCT_FSET(strpeek, flags, 0);
                STRUCT_FSET(strpeek, ctlbuf.len, -1);

                error = copyout(STRUCT_BUF(strpeek), (caddr_t)arg,
                    STRUCT_SIZE(strpeek));
                if (error == 0 && len >= 0)
                        *rvalp = 1;
                break;
        }

        case FIONREAD:
                /*
                 * let user know total number of bytes in message queue
                 */
                error = copyout((caddr_t)&fnp->fn_count, (caddr_t)arg,
                    sizeof (fnp->fn_count));
                if (error == 0)
                        *rvalp = 0;
                break;

        case I_SETSIG:
                /*
                 * let streams set up the signal masking for us
                 * we just check to see if it's set
                 * XXX : this interface should not be visible
                 *  i.e. STREAM's framework is exposed.
                 */
                error = strioctl(vp, cmd, arg, mode, U_TO_K, cr, rvalp);
                if (vp->v_stream->sd_sigflags & (S_INPUT|S_RDNORM|S_WRNORM))
                        fnp->fn_flag |= FIFOSETSIG;
                else
                        fnp->fn_flag &= ~FIFOSETSIG;
                break;

        case I_FLUSH:
                /*
                 * flush them message queues
                 */
                if (arg & ~FLUSHRW) {
                        error = EINVAL;
                        break;
                }
                if (arg & FLUSHR) {
                        fifo_fastflush(fnp);
                }
                fn_dest = fnp->fn_dest;
                if ((arg & FLUSHW)) {
                        fifo_fastflush(fn_dest);
                }
                /*
                 * wake up any sleeping readers or writers
                 * (waking readers probably doesn't make sense, but it
                 *  doesn't hurt; i.e. we just got rid of all the data
                 *  what's to read ?)
                 */
                if (fn_dest->fn_flag & (FIFOWANTW | FIFOWANTR)) {
                        fn_dest->fn_flag &= ~(FIFOWANTW | FIFOWANTR);
                        cv_broadcast(&fn_dest->fn_wait_cv);
                }
                *rvalp = 0;
                break;

        /*
         * Since no band data can ever get on a fifo in fast mode
         * just return 0.
         */
        case I_FLUSHBAND:
                error = 0;
                *rvalp = 0;
                break;

        case _I_GETPEERCRED:
                error = fifo_ioctl_getpeercred(fnp, arg, mode);
                break;

        /*
         * invalid calls for stream head or fifos
         */

        case I_POP:             /* shouldn't happen */
        case I_LOOK:
        case I_LINK:
        case I_PLINK:
        case I_UNLINK:
        case I_PUNLINK:

        /*
         * more invalid tty type of ioctls
         */

        case SRIOCSREDIR:
        case SRIOCISREDIR:
                error = EINVAL;
                break;

        }
        mutex_exit(&fn_lock->flk_lock);
        return (error);

turn_fastoff:
        fifo_fastoff(fnp);

stream_mode:
        /*
         * streams mode
         */
        mutex_exit(&fn_lock->flk_lock);
        return (fifo_strioctl(vp, cmd, arg, mode, cr, rvalp));

}

/*
 * FIFO is in STREAMS mode; STREAMS framework does most of the work.
 */
static int
fifo_strioctl(vnode_t *vp, int cmd, intptr_t arg, int mode, cred_t *cr,
    int *rvalp)
{
        fifonode_t      *fnp = VTOF(vp);
        int             error;
        fifolock_t      *fn_lock;

        if (cmd == _I_GETPEERCRED)
                return (fifo_ioctl_getpeercred(fnp, arg, mode));

        error = strioctl(vp, cmd, arg, mode, U_TO_K, cr, rvalp);

        switch (cmd) {
        /*
         * The FIFOSEND flag is set to inform other processes that a file
         * descriptor is pending at the stream head of this pipe.
         * The flag is cleared and the sending process is awoken when
         * this process has completed receiving the file descriptor.
         * XXX This could become out of sync if the process does I_SENDFDs
         * and opens on connld attached to the same pipe.
         */
        case I_RECVFD:
        case I_E_RECVFD:
                if (error == 0) {
                        fn_lock = fnp->fn_lock;
                        mutex_enter(&fn_lock->flk_lock);
                        if (fnp->fn_flag & FIFOSEND) {
                                fnp->fn_flag &= ~FIFOSEND;
                                cv_broadcast(&fnp->fn_dest->fn_wait_cv);
                        }
                        mutex_exit(&fn_lock->flk_lock);
                }
                break;
        default:
                break;
        }

        return (error);
}

/*
 * If shadowing a vnode (FIFOs), apply the fop_getattr to the shadowed
 * vnode to Obtain the node information. If not shadowing (pipes), obtain
 * the node information from the credentials structure.
 */
int
fifo_getattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *crp,
    caller_context_t *ct)
{
        int             error           = 0;
        fifonode_t      *fnp            = VTOF(vp);
        queue_t         *qp;
        qband_t         *bandp;
        fifolock_t      *fn_lock        = fnp->fn_lock;

        if (fnp->fn_realvp) {
                /*
                 * for FIFOs or mounted pipes
                 */
                if (error = fop_getattr(fnp->fn_realvp, vap, flags, crp, ct))
                        return (error);
                mutex_enter(&fn_lock->flk_lock);
                /* set current times from fnode, even if older than vnode */
                vap->va_atime.tv_sec = fnp->fn_atime;
                vap->va_atime.tv_nsec = 0;
                vap->va_mtime.tv_sec = fnp->fn_mtime;
                vap->va_mtime.tv_nsec = 0;
                vap->va_ctime.tv_sec = fnp->fn_ctime;
                vap->va_ctime.tv_nsec = 0;
        } else {
                /*
                 * for non-attached/ordinary pipes
                 */
                vap->va_mode = 0;
                mutex_enter(&fn_lock->flk_lock);
                vap->va_atime.tv_sec = fnp->fn_atime;
                vap->va_atime.tv_nsec = 0;
                vap->va_mtime.tv_sec = fnp->fn_mtime;
                vap->va_mtime.tv_nsec = 0;
                vap->va_ctime.tv_sec = fnp->fn_ctime;
                vap->va_ctime.tv_nsec = 0;
                vap->va_uid = crgetuid(crp);
                vap->va_gid = crgetgid(crp);
                vap->va_nlink = 0;
                vap->va_fsid = fifodev;
                vap->va_nodeid = (ino64_t)fnp->fn_ino;
                vap->va_rdev = 0;
        }
        vap->va_type = VFIFO;
        vap->va_blksize = PIPE_BUF;
        /*
         * Size is number of un-read bytes at the stream head and
         * nblocks is the unread bytes expressed in blocks.
         */
        if (vp->v_stream && (fnp->fn_flag & FIFOISOPEN)) {
                if ((fnp->fn_flag & FIFOFAST)) {
                        vap->va_size = (uoff_t)fnp->fn_count;
                } else {
                        qp = RD((strvp2wq(vp)));
                        vap->va_size = (uoff_t)qp->q_count;
                        if (qp->q_nband != 0) {
                                mutex_enter(QLOCK(qp));
                                for (bandp = qp->q_bandp; bandp;
                                    bandp = bandp->qb_next)
                                        vap->va_size += bandp->qb_count;
                                mutex_exit(QLOCK(qp));
                        }
                }
                vap->va_nblocks = (fsblkcnt64_t)btod(vap->va_size);
        } else {
                vap->va_size = 0;
                vap->va_nblocks = (fsblkcnt64_t)0;
        }
        mutex_exit(&fn_lock->flk_lock);
        vap->va_seq = 0;
        return (0);
}

/*
 * If shadowing a vnode, apply the fop_setattr to it, and to the fnode.
 * Otherwise, set the time and return 0.
 */
int
fifo_setattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *crp,
    caller_context_t *ctp)
{
        fifonode_t      *fnp    = VTOF(vp);
        int             error   = 0;
        fifolock_t      *fn_lock;

        if (fnp->fn_realvp)
                error = fop_setattr(fnp->fn_realvp, vap, flags, crp, ctp);
        if (error == 0) {
                fn_lock = fnp->fn_lock;
                mutex_enter(&fn_lock->flk_lock);
                if (vap->va_mask & VATTR_ATIME)
                        fnp->fn_atime = vap->va_atime.tv_sec;
                if (vap->va_mask & VATTR_MTIME)
                        fnp->fn_mtime = vap->va_mtime.tv_sec;
                fnp->fn_ctime = gethrestime_sec();
                mutex_exit(&fn_lock->flk_lock);
        }
        return (error);
}

/*
 * If shadowing a vnode, apply fop_access to it.
 * Otherwise, return 0 (allow all access).
 */
int
fifo_access(vnode_t *vp, int mode, int flags, cred_t *crp, caller_context_t *ct)
{
        if (VTOF(vp)->fn_realvp)
                return (fop_access(VTOF(vp)->fn_realvp, mode, flags, crp, ct));
        else
                return (0);
}

/*
 * This can be called if creat or an open with O_CREAT is done on the root
 * of a lofs mount where the mounted entity is a fifo.
 */
/*ARGSUSED*/
static int
fifo_create(struct vnode *dvp, char *name, vattr_t *vap, enum vcexcl excl,
    int mode, struct vnode **vpp, struct cred *cr, int flag,
    caller_context_t *ct, vsecattr_t *vsecp)
{
        int error;

        ASSERT(dvp && (dvp->v_flag & VROOT) && *name == '\0');
        if (excl == NONEXCL) {
                if (mode && (error = fifo_access(dvp, mode, 0, cr, ct)))
                        return (error);
                VN_HOLD(dvp);
                return (0);
        }
        return (EEXIST);
}

/*
 * If shadowing a vnode, apply the fop_fsync to it.
 * Otherwise, return 0.
 */
int
fifo_fsync(vnode_t *vp, int syncflag, cred_t *crp, caller_context_t *ct)
{
        fifonode_t      *fnp    = VTOF(vp);
        vattr_t         va;

        if (fnp->fn_realvp == NULL)
                return (0);

        bzero((caddr_t)&va, sizeof (va));
        va.va_mask = VATTR_MTIME | VATTR_ATIME;
        if (fop_getattr(fnp->fn_realvp, &va, 0, crp, ct) == 0) {
                va.va_mask = 0;
                if (fnp->fn_mtime > va.va_mtime.tv_sec) {
                        va.va_mtime.tv_sec = fnp->fn_mtime;
                        va.va_mask = VATTR_MTIME;
                }
                if (fnp->fn_atime > va.va_atime.tv_sec) {
                        va.va_atime.tv_sec = fnp->fn_atime;
                        va.va_mask |= VATTR_ATIME;
                }
                if (va.va_mask != 0)
                        (void) fop_setattr(fnp->fn_realvp, &va, 0, crp, ct);
        }
        return (fop_fsync(fnp->fn_realvp, syncflag, crp, ct));
}

/*
 * Called when the upper level no longer holds references to the
 * vnode. Sync the file system and free the fifonode.
 */
void
fifo_inactive(vnode_t *vp, cred_t *crp, caller_context_t *ct)
{
        fifonode_t      *fnp;
        fifolock_t      *fn_lock;

        mutex_enter(&ftable_lock);
        mutex_enter(&vp->v_lock);
        ASSERT(vp->v_count >= 1);
        VN_RELE_LOCKED(vp);
        if (vp->v_count != 0) {
                /*
                 * Somebody accessed the fifo before we got a chance to
                 * remove it.  They will remove it when they do a vn_rele.
                 */
                mutex_exit(&vp->v_lock);
                mutex_exit(&ftable_lock);
                return;
        }
        mutex_exit(&vp->v_lock);

        fnp = VTOF(vp);

        /*
         * remove fifo from fifo list so that no other process
         * can grab it.
         * Drop the reference count on the fifo node's
         * underlying vfs.
         */
        if (fnp->fn_realvp) {
                (void) fiforemove(fnp);
                mutex_exit(&ftable_lock);
                (void) fifo_fsync(vp, FSYNC, crp, ct);
                VN_RELE(fnp->fn_realvp);
                VFS_RELE(vp->v_vfsp);
                vp->v_vfsp = NULL;
        } else
                mutex_exit(&ftable_lock);

        fn_lock = fnp->fn_lock;

        mutex_enter(&fn_lock->flk_lock);
        ASSERT(vp->v_stream == NULL);
        ASSERT(vp->v_count == 0);
        /*
         * if this is last reference to the lock, then we can
         * free everything up.
         */
        if (--fn_lock->flk_ref == 0) {
                mutex_exit(&fn_lock->flk_lock);
                ASSERT(fnp->fn_open == 0);
                ASSERT(fnp->fn_dest->fn_open == 0);
                if (fnp->fn_mp) {
                        freemsg(fnp->fn_mp);
                        fnp->fn_mp = NULL;
                        fnp->fn_count = 0;
                }
                if (fnp->fn_pcredp != NULL) {
                        crfree(fnp->fn_pcredp);
                        fnp->fn_pcredp = NULL;
                }
                if (fnp->fn_flag & ISPIPE) {
                        fifonode_t *fn_dest = fnp->fn_dest;

                        vp = FTOV(fn_dest);
                        if (fn_dest->fn_mp) {
                                freemsg(fn_dest->fn_mp);
                                fn_dest->fn_mp = NULL;
                                fn_dest->fn_count = 0;
                        }
                        if (fn_dest->fn_pcredp != NULL) {
                                crfree(fn_dest->fn_pcredp);
                                fn_dest->fn_pcredp = NULL;
                        }
                        kmem_cache_free(pipe_cache, (fifodata_t *)fn_lock);
                } else
                        kmem_cache_free(fnode_cache, (fifodata_t *)fn_lock);
        } else {
                mutex_exit(&fn_lock->flk_lock);
        }
}

/*
 * If shadowing a vnode, apply the fop_fid to it.
 * Otherwise, return EINVAL.
 */
int
fifo_fid(vnode_t *vp, fid_t *fidfnp, caller_context_t *ct)
{
        if (VTOF(vp)->fn_realvp)
                return (fop_fid(VTOF(vp)->fn_realvp, fidfnp, ct));
        else
                return (EINVAL);
}

/*
 * Lock a fifonode.
 */
/* ARGSUSED */
int
fifo_rwlock(vnode_t *vp, int write_lock, caller_context_t *ctp)
{
        return (-1);
}

/*
 * Unlock a fifonode.
 */
/* ARGSUSED */
void
fifo_rwunlock(vnode_t *vp, int write_lock, caller_context_t *ctp)
{
}

/*
 * Return error since seeks are not allowed on pipes.
 */
/*ARGSUSED*/
int
fifo_seek(vnode_t *vp, offset_t ooff, offset_t *noffp, caller_context_t *ct)
{
        return (ESPIPE);
}

/*
 * If there is a realvp associated with vp, return it.
 */
int
fifo_realvp(vnode_t *vp, vnode_t **vpp, caller_context_t *ct)
{
        vnode_t *rvp;

        if ((rvp = VTOF(vp)->fn_realvp) != NULL) {
                vp = rvp;
                if (fop_realvp(vp, &rvp, ct) == 0)
                        vp = rvp;
        }

        *vpp = vp;
        return (0);
}

/*
 * Poll for interesting events on a stream pipe
 */
/* ARGSUSED */
int
fifo_poll(vnode_t *vp, short events, int anyyet, short *reventsp,
    pollhead_t **phpp, caller_context_t *ct)
{
        fifonode_t      *fnp, *fn_dest;
        fifolock_t      *fn_lock;
        int             retevents;
        struct stdata   *stp;

        ASSERT(vp->v_stream != NULL);

        stp = vp->v_stream;
        retevents       = 0;
        fnp             = VTOF(vp);
        fn_dest         = fnp->fn_dest;
        fn_lock         = fnp->fn_lock;

        if (polllock(&stp->sd_pollist, &fn_lock->flk_lock) != 0) {
                *reventsp = POLLNVAL;
                return (0);
        }

        /*
         * see if FIFO/pipe open
         */
        if ((fnp->fn_flag & FIFOISOPEN) == 0) {
                if (((events & (POLLIN | POLLRDNORM | POLLPRI | POLLRDBAND)) &&
                    fnp->fn_rcnt == 0) ||
                    ((events & (POLLWRNORM | POLLWRBAND)) &&
                    fnp->fn_wcnt == 0)) {
                        mutex_exit(&fnp->fn_lock->flk_lock);
                        *reventsp = POLLERR;
                        return (0);
                }
        }

        /*
         * if not in fast mode, let the stream head take care of it
         */
        if (!(fnp->fn_flag & FIFOFAST)) {
                mutex_exit(&fnp->fn_lock->flk_lock);
                goto stream_mode;
        }

        /*
         * If this is a pipe.. check to see if the other
         * end is gone.  If we are a fifo, check to see
         * if write end is gone.
         */

        if ((fnp->fn_flag & ISPIPE) && (fn_dest->fn_open == 0)) {
                retevents = POLLHUP;
        } else if ((fnp->fn_flag & (FIFOCLOSE | ISPIPE)) == FIFOCLOSE &&
            (fn_dest->fn_wcnt == 0)) {
                /*
                 * no writer at other end.
                 * it was closed (versus yet to be opened)
                 */
                        retevents = POLLHUP;
        } else if (events & (POLLWRNORM | POLLWRBAND)) {
                if (events & POLLWRNORM) {
                        if (fn_dest->fn_count < Fifohiwat)
                                retevents = POLLWRNORM;
                        else
                                fnp->fn_flag |= FIFOHIWATW;
                }
                /*
                 * This is always true for fast pipes
                 * (Note: will go to STREAMS mode if band data is written)
                 */
                if (events & POLLWRBAND)
                        retevents |= POLLWRBAND;
        }
        if (events & (POLLIN | POLLRDNORM)) {
                if (fnp->fn_count)
                        retevents |= (events & (POLLIN | POLLRDNORM));
        }

        /*
         * if we happened to get something and we're not edge-triggered, return
         */
        if ((*reventsp = (short)retevents) != 0 && !(events & POLLET)) {
                mutex_exit(&fnp->fn_lock->flk_lock);
                return (0);
        }

        /*
         * If poll() has not found any events yet or we're edge-triggered, set
         * up event cell to wake up the poll if a requested event occurs on this
         * pipe/fifo.
         */
        if (!anyyet) {
                if (events & POLLWRNORM)
                        fnp->fn_flag |= FIFOPOLLW;
                if (events & (POLLIN | POLLRDNORM))
                        fnp->fn_flag |= FIFOPOLLR;
                if (events & POLLRDBAND)
                        fnp->fn_flag |= FIFOPOLLRBAND;
                /*
                 * XXX Don't like exposing this from streams
                 */
                *phpp = &stp->sd_pollist;
        }
        mutex_exit(&fnp->fn_lock->flk_lock);
        return (0);
stream_mode:
        return (strpoll(stp, events, anyyet, reventsp, phpp));
}

/*
 * POSIX pathconf() support.
 */
/* ARGSUSED */
int
fifo_pathconf(vnode_t *vp, int cmd, ulong_t *valp, cred_t *cr,
    caller_context_t *ct)
{
        ulong_t val;
        int error = 0;

        switch (cmd) {

        case _PC_LINK_MAX:
                val = MAXLINK;
                break;

        case _PC_MAX_CANON:
                val = MAX_CANON;
                break;

        case _PC_MAX_INPUT:
                val = MAX_INPUT;
                break;

        case _PC_NAME_MAX:
                error = EINVAL;
                break;

        case _PC_PATH_MAX:
        case _PC_SYMLINK_MAX:
                val = MAXPATHLEN;
                break;

        case _PC_PIPE_BUF:
                val = PIPE_BUF;
                break;

        case _PC_NO_TRUNC:
                if (vp->v_vfsp->vfs_flag & VFS_NOTRUNC)
                        val = 1;        /* NOTRUNC is enabled for vp */
                else
                        val = (ulong_t)-1;
                break;

        case _PC_VDISABLE:
                val = _POSIX_VDISABLE;
                break;

        case _PC_CHOWN_RESTRICTED:
                if (rstchown)
                        val = rstchown;         /* chown restricted enabled */
                else
                        val = (ulong_t)-1;
                break;

        case _PC_FILESIZEBITS:
                val = (ulong_t)-1;
                break;

        default:
                if (VTOF(vp)->fn_realvp)
                        error = fop_pathconf(VTOF(vp)->fn_realvp, cmd,
                            &val, cr, ct);
                else
                        error = EINVAL;
                break;
        }

        if (error == 0)
                *valp = val;
        return (error);
}

/*
 * If shadowing a vnode, apply fop_setsecattr to it.
 * Otherwise, return NOSYS.
 */
int
fifo_setsecattr(struct vnode *vp, vsecattr_t *vsap, int flag, struct cred *crp,
    caller_context_t *ct)
{
        int error;

        /*
         * The acl(2) system call tries to grab the write lock on the
         * file when setting an ACL, but fifofs does not implement
         * fop_rwlock or fop_rwunlock, so we do it here instead.
         */
        if (VTOF(vp)->fn_realvp) {
                (void) fop_rwlock(VTOF(vp)->fn_realvp, V_WRITELOCK_TRUE, ct);
                error = fop_setsecattr(VTOF(vp)->fn_realvp, vsap, flag,
                    crp, ct);
                fop_rwunlock(VTOF(vp)->fn_realvp, V_WRITELOCK_TRUE, ct);
                return (error);
        } else
                return (fs_nosys());
}

/*
 * If shadowing a vnode, apply fop_getsecattr to it. Otherwise, fabricate
 * an ACL from the permission bits that fifo_getattr() makes up.
 */
int
fifo_getsecattr(struct vnode *vp, vsecattr_t *vsap, int flag, struct cred *crp,
    caller_context_t *ct)
{
        if (VTOF(vp)->fn_realvp)
                return (fop_getsecattr(VTOF(vp)->fn_realvp, vsap, flag,
                    crp, ct));
        else
                return (fs_fab_acl(vp, vsap, flag, crp, ct));
}


/*
 * Set the FIFOSTAYFAST flag so nobody can turn the fifo into stream mode.
 * If the flag is already set then wait until it is removed - releasing
 * the lock.
 * If the fifo switches into stream mode while we are waiting, return failure.
 */
static boolean_t
fifo_stayfast_enter(fifonode_t *fnp)
{
        ASSERT(MUTEX_HELD(&fnp->fn_lock->flk_lock));
        while (fnp->fn_flag & FIFOSTAYFAST) {
                fnp->fn_flag |= FIFOWAITMODE;
                cv_wait(&fnp->fn_wait_cv, &fnp->fn_lock->flk_lock);
                fnp->fn_flag &= ~FIFOWAITMODE;
        }
        if (!(fnp->fn_flag & FIFOFAST))
                return (B_FALSE);

        fnp->fn_flag |= FIFOSTAYFAST;
        return (B_TRUE);
}

/*
 * Unset the FIFOSTAYFAST flag and notify anybody waiting for this flag
 * to be removed:
 *      - threads wanting to turn into stream mode waiting in fifo_fastoff(),
 *      - other writers threads waiting in fifo_stayfast_enter().
 */
static void
fifo_stayfast_exit(fifonode_t *fnp)
{
        fifonode_t *fn_dest = fnp->fn_dest;

        ASSERT(MUTEX_HELD(&fnp->fn_lock->flk_lock));

        fnp->fn_flag &= ~FIFOSTAYFAST;

        if (fnp->fn_flag & FIFOWAITMODE)
                cv_broadcast(&fnp->fn_wait_cv);

        if ((fnp->fn_flag & ISPIPE) && (fn_dest->fn_flag & FIFOWAITMODE))
                cv_broadcast(&fn_dest->fn_wait_cv);
}