Stop abusing a `struct buf' for state information. Use new `struct physio_stat'
and use kmutex and kcondvar here. Fix an error introduced with B_ERROR removal where reading at EOM returned EIO. Approved by: Andrew Doran <ad@netbsd.org>
This commit is contained in:
hannken
parent
97af1559fd
commit
d72d03c5d7
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@ -1,4 +1,4 @@
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/* $NetBSD: kern_physio.c,v 1.83 2007/07/29 12:15:45 ad Exp $ */
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/* $NetBSD: kern_physio.c,v 1.84 2007/09/18 08:34:34 hannken Exp $ */
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/*-
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* Copyright (c) 1982, 1986, 1990, 1993
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@ -71,7 +71,7 @@
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_physio.c,v 1.83 2007/07/29 12:15:45 ad Exp $");
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__KERNEL_RCSID(0, "$NetBSD: kern_physio.c,v 1.84 2007/09/18 08:34:34 hannken Exp $");
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#include <sys/param.h>
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#include <sys/systm.h>
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@ -79,6 +79,7 @@ __KERNEL_RCSID(0, "$NetBSD: kern_physio.c,v 1.83 2007/07/29 12:15:45 ad Exp $");
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#include <sys/proc.h>
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#include <sys/once.h>
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#include <sys/workqueue.h>
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#include <sys/kmem.h>
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#include <uvm/uvm_extern.h>
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@ -105,9 +106,16 @@ struct workqueue *physio_workqueue;
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#define DPRINTF(a) /* nothing */
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#endif /* defined(PHYSIO_DEBUG) */
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/* abuse these members/flags of struct buf */
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#define b_running b_freelistindex
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#define b_endoffset b_lblkno
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struct physio_stat {
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int ps_running;
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int ps_error;
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int ps_failed;
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off_t ps_endoffset;
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kmutex_t ps_lock;
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kcondvar_t ps_cv;
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};
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/* abuse these flags of struct buf */
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#define B_DONTFREE B_AGE
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/*
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@ -146,7 +154,7 @@ physio_done(struct work *wk, void *dummy)
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struct buf *bp = (void *)wk;
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size_t todo = bp->b_bufsize;
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size_t done = bp->b_bcount - bp->b_resid;
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struct buf *mbp = bp->b_private;
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struct physio_stat *ps = bp->b_private;
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KASSERT(&bp->b_work == wk);
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KASSERT(bp->b_bcount <= todo);
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@ -157,7 +165,7 @@ physio_done(struct work *wk, void *dummy)
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vunmapbuf(bp, todo);
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uvm_vsunlock(bp->b_proc->p_vmspace, bp->b_data, todo);
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simple_lock(&mbp->b_interlock);
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mutex_enter(&ps->ps_lock);
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if (__predict_false(done != todo)) {
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off_t endoffset = dbtob(bp->b_blkno) + done;
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@ -168,33 +176,30 @@ physio_done(struct work *wk, void *dummy)
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* ie. the one at the lowest offset.
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*/
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KASSERT(mbp->b_endoffset != endoffset);
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KASSERT(ps->ps_endoffset != endoffset);
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DPRINTF(("%s: error=%d at %" PRIu64 " - %" PRIu64
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", blkno=%" PRIu64 ", bcount=%d, flags=0x%x\n",
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__func__, bp->b_error, dbtob(bp->b_blkno), endoffset,
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bp->b_blkno, bp->b_bcount, bp->b_flags));
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if (mbp->b_endoffset == -1 || endoffset < mbp->b_endoffset) {
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DPRINTF(("%s: mbp=%p, error %d -> %d, endoff %" PRIu64
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if (ps->ps_endoffset == -1 || endoffset < ps->ps_endoffset) {
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DPRINTF(("%s: ps=%p, error %d -> %d, endoff %" PRIu64
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" -> %" PRIu64 "\n",
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__func__, mbp,
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mbp->b_error, bp->b_error,
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mbp->b_endoffset, endoffset));
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__func__, ps,
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ps->ps_error, bp->b_error,
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ps->ps_endoffset, endoffset));
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mbp->b_endoffset = endoffset;
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mbp->b_error = bp->b_error;
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ps->ps_endoffset = endoffset;
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ps->ps_error = bp->b_error;
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}
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mbp->b_error = EIO;
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ps->ps_failed++;
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} else {
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KASSERT(bp->b_error == 0);
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}
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mbp->b_running--;
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if ((mbp->b_flags & B_WANTED) != 0) {
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mbp->b_flags &= ~B_WANTED;
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wakeup(mbp);
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}
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simple_unlock(&mbp->b_interlock);
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ps->ps_running--;
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cv_signal(&ps->ps_cv);
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mutex_exit(&ps->ps_lock);
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putphysbuf(bp);
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}
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@ -203,10 +208,10 @@ static void
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physio_biodone(struct buf *bp)
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{
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#if defined(DIAGNOSTIC)
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struct buf *mbp = bp->b_private;
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struct physio_stat *ps = bp->b_private;
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size_t todo = bp->b_bufsize;
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KASSERT(mbp->b_running > 0);
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KASSERT(ps->ps_running > 0);
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KASSERT(bp->b_bcount <= todo);
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KASSERT(bp->b_resid <= bp->b_bcount);
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#endif /* defined(DIAGNOSTIC) */
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@ -214,22 +219,14 @@ physio_biodone(struct buf *bp)
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workqueue_enqueue(physio_workqueue, &bp->b_work, NULL);
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}
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static int
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physio_wait(struct buf *bp, int n, const char *wchan)
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static void
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physio_wait(struct physio_stat *ps, int n)
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{
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int error = 0;
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LOCK_ASSERT(simple_lock_held(&bp->b_interlock));
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KASSERT(mutex_owned(&ps->ps_lock));
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while (bp->b_running > n) {
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bp->b_flags |= B_WANTED;
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error = ltsleep(bp, PRIBIO + 1, wchan, 0, &bp->b_interlock);
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if (error) {
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break;
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}
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}
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return error;
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while (ps->ps_running > n)
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cv_wait(&ps->ps_cv, &ps->ps_lock);
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}
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static int
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@ -262,9 +259,8 @@ physio(void (*strategy)(struct buf *), struct buf *obp, dev_t dev, int flags,
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struct proc *p = l->l_proc;
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int i, s;
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int error;
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int error2;
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struct buf *bp = NULL;
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struct buf *mbp;
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struct physio_stat *ps;
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int concurrency = PHYSIO_CONCURRENCY - 1;
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error = RUN_ONCE(&physio_initialized, physio_init);
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@ -277,6 +273,15 @@ physio(void (*strategy)(struct buf *), struct buf *obp, dev_t dev, int flags,
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flags &= B_READ | B_WRITE;
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if ((ps = kmem_zalloc(sizeof(*ps), KM_SLEEP)) == NULL)
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return ENOMEM;
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/* ps->ps_running = 0; */
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/* ps->ps_error = 0; */
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/* ps->ps_failed = 0; */
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ps->ps_endoffset = -1;
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mutex_init(&ps->ps_lock, MUTEX_DEFAULT, IPL_NONE);
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cv_init(&ps->ps_cv, "physio");
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/* Make sure we have a buffer, creating one if necessary. */
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if (obp != NULL) {
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/* [raise the processor priority level to splbio;] */
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@ -301,10 +306,6 @@ physio(void (*strategy)(struct buf *), struct buf *obp, dev_t dev, int flags,
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concurrency = 0; /* see "XXXkludge" comment below */
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}
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mbp = getphysbuf();
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mbp->b_running = 0;
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mbp->b_endoffset = -1;
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uvm_lwp_hold(l);
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for (i = 0; i < uio->uio_iovcnt; i++) {
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@ -315,16 +316,12 @@ physio(void (*strategy)(struct buf *), struct buf *obp, dev_t dev, int flags,
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size_t todo;
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vaddr_t endp;
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simple_lock(&mbp->b_interlock);
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if (mbp->b_error != 0) {
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mutex_enter(&ps->ps_lock);
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if (ps->ps_failed != 0) {
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goto done_locked;
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}
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error = physio_wait(mbp, sync ? 0 : concurrency,
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"physio1");
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if (error) {
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goto done_locked;
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}
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simple_unlock(&mbp->b_interlock);
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physio_wait(ps, sync ? 0 : concurrency);
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mutex_exit(&ps->ps_lock);
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if (obp != NULL) {
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/*
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* XXXkludge
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@ -336,7 +333,7 @@ physio(void (*strategy)(struct buf *), struct buf *obp, dev_t dev, int flags,
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}
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bp->b_dev = dev;
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bp->b_proc = p;
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bp->b_private = mbp;
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bp->b_private = ps;
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bp->b_vp = NULL;
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/*
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@ -398,9 +395,9 @@ physio(void (*strategy)(struct buf *), struct buf *obp, dev_t dev, int flags,
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BIO_SETPRIO(bp, BPRIO_TIMECRITICAL);
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simple_lock(&mbp->b_interlock);
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mbp->b_running++;
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simple_unlock(&mbp->b_interlock);
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mutex_enter(&ps->ps_lock);
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ps->ps_running++;
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mutex_exit(&ps->ps_lock);
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/* [call strategy to start the transfer] */
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(*strategy)(bp);
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@ -414,31 +411,30 @@ physio(void (*strategy)(struct buf *), struct buf *obp, dev_t dev, int flags,
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}
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done:
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simple_lock(&mbp->b_interlock);
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mutex_enter(&ps->ps_lock);
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done_locked:
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error2 = physio_wait(mbp, 0, "physio2");
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if (error == 0) {
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error = error2;
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}
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simple_unlock(&mbp->b_interlock);
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physio_wait(ps, 0);
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mutex_exit(&ps->ps_lock);
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if (mbp->b_error != 0) {
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if (ps->ps_failed != 0) {
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off_t delta;
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delta = uio->uio_offset - mbp->b_endoffset;
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delta = uio->uio_offset - ps->ps_endoffset;
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KASSERT(delta > 0);
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uio->uio_resid += delta;
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/* uio->uio_offset = mbp->b_endoffset; */
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/* uio->uio_offset = ps->ps_endoffset; */
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} else {
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KASSERT(mbp->b_endoffset == -1);
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KASSERT(ps->ps_endoffset == -1);
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}
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if (bp != NULL) {
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putphysbuf(bp);
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}
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if (error == 0) {
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error = mbp->b_error;
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error = ps->ps_error;
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}
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putphysbuf(mbp);
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mutex_destroy(&ps->ps_lock);
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cv_destroy(&ps->ps_cv);
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kmem_free(ps, sizeof(*ps));
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/*
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* [clean up the state of the buffer]
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