29f88f470e
civilized way which doesn't cause grief. The problem is that it is not generally safe to cast a "struct bio *" to a "struct buf *". Things like ccd, vinum, ata-raid and GEOM constructs bio's which are not entrails of a struct buf. Also, curthread may or may not have anything to do with the I/O request at hand. The correct solution can either be to tag struct bio's with a priority derived from the requesting threads nice and have disksort act on this field, this wouldn't address the "silly-seek syndrome" where two equal processes bang the diskheads from one edge to the other of the disk repeatedly. Alternatively, and probably better: a sleep should be introduced either at the time the I/O is requested or at the time it is completed where we can be sure to sleep in the right thread. The sleep also needs to be in constant timeunits, 1/hz can be practicaly any sub-second size, at high HZ the current code practically doesn't do anything.
426 lines
12 KiB
C
426 lines
12 KiB
C
/*
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* Copyright (c) 1982, 1986, 1988, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)ufs_disksubr.c 8.5 (Berkeley) 1/21/94
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bio.h>
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#include <sys/buf.h>
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#include <sys/conf.h>
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#include <sys/kernel.h>
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#include <sys/disklabel.h>
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#include <sys/diskslice.h>
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#include <sys/syslog.h>
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#include <machine/atomic.h>
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#ifdef notquite
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/*
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* Mutex to use when delaying niced I/O bound processes in bioqdisksort().
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*/
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static struct mtx dksort_mtx;
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static void
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dksort_init(void)
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{
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mtx_init(&dksort_mtx, "dksort", NULL, MTX_DEF);
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}
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SYSINIT(dksort, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, dksort_init, NULL)
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#endif
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/*
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* Seek sort for disks.
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*
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* The buf_queue keep two queues, sorted in ascending block order. The first
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* queue holds those requests which are positioned after the current block
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* (in the first request); the second, which starts at queue->switch_point,
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* holds requests which came in after their block number was passed. Thus
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* we implement a one way scan, retracting after reaching the end of the drive
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* to the first request on the second queue, at which time it becomes the
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* first queue.
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*
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* A one-way scan is natural because of the way UNIX read-ahead blocks are
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* allocated.
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*/
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void
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bioqdisksort(bioq, bp)
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struct bio_queue_head *bioq;
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struct bio *bp;
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{
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struct bio *bq;
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struct bio *bn;
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struct bio *be;
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#ifdef notquite
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struct thread *td = curthread;
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if (td && td->td_ksegrp->kg_nice > 0) {
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TAILQ_FOREACH(bn, &bioq->queue, bio_queue)
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if (BIOTOBUF(bp)->b_vp != BIOTOBUF(bn)->b_vp)
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break;
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if (bn != NULL) {
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mtx_lock(&dksort_mtx);
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msleep((caddr_t)&dksort_mtx, &dksort_mtx,
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PPAUSE | PCATCH | PDROP, "ioslow",
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td->td_ksegrp->kg_nice);
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}
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}
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#endif
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if (!atomic_cmpset_int(&bioq->busy, 0, 1))
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panic("Recursing in bioqdisksort()");
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be = TAILQ_LAST(&bioq->queue, bio_queue);
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/*
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* If the queue is empty or we are an
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* ordered transaction, then it's easy.
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*/
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if ((bq = bioq_first(bioq)) == NULL) {
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bioq_insert_tail(bioq, bp);
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bioq->busy = 0;
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return;
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} else if (bioq->insert_point != NULL) {
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/*
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* A certain portion of the list is
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* "locked" to preserve ordering, so
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* we can only insert after the insert
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* point.
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*/
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bq = bioq->insert_point;
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} else {
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/*
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* If we lie before the last removed (currently active)
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* request, and are not inserting ourselves into the
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* "locked" portion of the list, then we must add ourselves
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* to the second request list.
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*/
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if (bp->bio_pblkno < bioq->last_pblkno) {
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bq = bioq->switch_point;
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/*
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* If we are starting a new secondary list,
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* then it's easy.
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*/
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if (bq == NULL) {
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bioq->switch_point = bp;
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bioq_insert_tail(bioq, bp);
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bioq->busy = 0;
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return;
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}
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/*
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* If we lie ahead of the current switch point,
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* insert us before the switch point and move
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* the switch point.
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*/
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if (bp->bio_pblkno < bq->bio_pblkno) {
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bioq->switch_point = bp;
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TAILQ_INSERT_BEFORE(bq, bp, bio_queue);
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bioq->busy = 0;
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return;
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}
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} else {
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if (bioq->switch_point != NULL)
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be = TAILQ_PREV(bioq->switch_point,
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bio_queue, bio_queue);
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/*
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* If we lie between last_pblkno and bq,
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* insert before bq.
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*/
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if (bp->bio_pblkno < bq->bio_pblkno) {
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TAILQ_INSERT_BEFORE(bq, bp, bio_queue);
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bioq->busy = 0;
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return;
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}
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}
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}
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/*
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* Request is at/after our current position in the list.
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* Optimize for sequential I/O by seeing if we go at the tail.
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*/
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if (bp->bio_pblkno > be->bio_pblkno) {
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TAILQ_INSERT_AFTER(&bioq->queue, be, bp, bio_queue);
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bioq->busy = 0;
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return;
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}
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/* Otherwise, insertion sort */
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while ((bn = TAILQ_NEXT(bq, bio_queue)) != NULL) {
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/*
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* We want to go after the current request if it is the end
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* of the first request list, or if the next request is a
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* larger cylinder than our request.
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*/
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if (bn == bioq->switch_point
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|| bp->bio_pblkno < bn->bio_pblkno)
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break;
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bq = bn;
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}
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TAILQ_INSERT_AFTER(&bioq->queue, bq, bp, bio_queue);
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bioq->busy = 0;
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}
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/*
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* Attempt to read a disk label from a device using the indicated strategy
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* routine. The label must be partly set up before this: secpercyl, secsize
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* and anything required in the strategy routine (e.g., dummy bounds for the
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* partition containing the label) must be filled in before calling us.
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* Returns NULL on success and an error string on failure.
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*/
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char *
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readdisklabel(dev, lp)
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dev_t dev;
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register struct disklabel *lp;
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{
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register struct buf *bp;
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struct disklabel *dlp;
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char *msg = NULL;
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bp = geteblk((int)lp->d_secsize);
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bp->b_dev = dev;
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bp->b_blkno = LABELSECTOR * ((int)lp->d_secsize/DEV_BSIZE);
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bp->b_bcount = lp->d_secsize;
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bp->b_flags &= ~B_INVAL;
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bp->b_iocmd = BIO_READ;
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DEV_STRATEGY(bp, 1);
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if (bufwait(bp))
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msg = "I/O error";
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else if (bp->b_resid != 0)
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msg = "disk too small for a label";
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else for (dlp = (struct disklabel *)bp->b_data;
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dlp <= (struct disklabel *)((char *)bp->b_data +
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lp->d_secsize - sizeof(*dlp));
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dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
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if (dlp->d_magic != DISKMAGIC || dlp->d_magic2 != DISKMAGIC) {
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if (msg == NULL)
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msg = "no disk label";
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} else if (dlp->d_npartitions > MAXPARTITIONS ||
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dkcksum(dlp) != 0)
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msg = "disk label corrupted";
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else {
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*lp = *dlp;
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msg = NULL;
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break;
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}
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}
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bp->b_flags |= B_INVAL | B_AGE;
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brelse(bp);
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return (msg);
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}
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/*
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* Check new disk label for sensibility before setting it.
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*/
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int
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setdisklabel(olp, nlp, openmask)
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register struct disklabel *olp, *nlp;
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u_long openmask;
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{
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register int i;
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register struct partition *opp, *npp;
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/*
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* Check it is actually a disklabel we are looking at.
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*/
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if (nlp->d_magic != DISKMAGIC || nlp->d_magic2 != DISKMAGIC ||
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dkcksum(nlp) != 0)
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return (EINVAL);
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/*
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* For each partition that we think is open,
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*/
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while ((i = ffs((long)openmask)) != 0) {
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i--;
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/*
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* Check it is not changing....
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*/
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openmask &= ~(1 << i);
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if (nlp->d_npartitions <= i)
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return (EBUSY);
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opp = &olp->d_partitions[i];
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npp = &nlp->d_partitions[i];
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if (npp->p_offset != opp->p_offset || npp->p_size < opp->p_size)
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return (EBUSY);
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/*
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* Copy internally-set partition information
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* if new label doesn't include it. XXX
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* (If we are using it then we had better stay the same type)
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* This is possibly dubious, as someone else noted (XXX)
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*/
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if (npp->p_fstype == FS_UNUSED && opp->p_fstype != FS_UNUSED) {
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npp->p_fstype = opp->p_fstype;
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npp->p_fsize = opp->p_fsize;
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npp->p_frag = opp->p_frag;
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npp->p_cpg = opp->p_cpg;
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}
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}
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nlp->d_checksum = 0;
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nlp->d_checksum = dkcksum(nlp);
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*olp = *nlp;
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return (0);
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}
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/*
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* Write disk label back to device after modification.
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*/
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int
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writedisklabel(dev, lp)
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dev_t dev;
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register struct disklabel *lp;
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{
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struct buf *bp;
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struct disklabel *dlp;
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int error = 0;
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if (lp->d_partitions[RAW_PART].p_offset != 0)
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return (EXDEV); /* not quite right */
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bp = geteblk((int)lp->d_secsize);
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bp->b_dev = dkmodpart(dev, RAW_PART);
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bp->b_blkno = LABELSECTOR * ((int)lp->d_secsize/DEV_BSIZE);
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bp->b_bcount = lp->d_secsize;
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#if 1
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/*
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* We read the label first to see if it's there,
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* in which case we will put ours at the same offset into the block..
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* (I think this is stupid [Julian])
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* Note that you can't write a label out over a corrupted label!
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* (also stupid.. how do you write the first one? by raw writes?)
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*/
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bp->b_flags &= ~B_INVAL;
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bp->b_iocmd = BIO_READ;
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DEV_STRATEGY(bp, 1);
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error = bufwait(bp);
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if (error)
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goto done;
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if (bp->b_resid != 0) {
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error = ENOSPC;
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goto done;
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}
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for (dlp = (struct disklabel *)bp->b_data;
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dlp <= (struct disklabel *)
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((char *)bp->b_data + lp->d_secsize - sizeof(*dlp));
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dlp = (struct disklabel *)((char *)dlp + sizeof(long))) {
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if (dlp->d_magic == DISKMAGIC && dlp->d_magic2 == DISKMAGIC &&
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dkcksum(dlp) == 0) {
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*dlp = *lp;
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bp->b_flags &= ~B_DONE;
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bp->b_iocmd = BIO_WRITE;
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#ifdef __alpha__
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alpha_fix_srm_checksum(bp);
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#endif
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DEV_STRATEGY(bp, 1);
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error = bufwait(bp);
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goto done;
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}
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}
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error = ESRCH;
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done:
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#else
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bzero(bp->b_data, lp->d_secsize);
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dlp = (struct disklabel *)bp->b_data;
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*dlp = *lp;
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bp->b_flags &= ~B_INVAL;
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bp->b_iocmd = BIO_WRITE;
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DEV_STRATEGY(bp, 1);
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error = bufwait(bp);
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#endif
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bp->b_flags |= B_INVAL | B_AGE;
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brelse(bp);
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return (error);
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}
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/*
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* Disk error is the preface to plaintive error messages
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* about failing disk transfers. It prints messages of the form
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hp0g: hard error reading fsbn 12345 of 12344-12347 (hp0 bn %d cn %d tn %d sn %d)
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* if the offset of the error in the transfer and a disk label
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* are both available. blkdone should be -1 if the position of the error
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* is unknown; the disklabel pointer may be null from drivers that have not
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* been converted to use them. The message is printed with printf.
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* The message should be completed with at least a newline. There is no
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* trailing space.
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*/
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void
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diskerr(bp, what, blkdone, lp)
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struct bio *bp;
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char *what;
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int blkdone;
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register struct disklabel *lp;
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{
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int part = dkpart(bp->bio_dev);
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char partname[2];
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char *sname;
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daddr_t sn;
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*partname = '\0';
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sname = bp->bio_dev->si_name;
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printf("%s%s: %s %sing fsbn ", sname, partname, what,
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bp->bio_cmd == BIO_READ ? "read" : "writ");
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sn = bp->bio_blkno;
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if (bp->bio_bcount <= DEV_BSIZE)
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printf("%ld", (long)sn);
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else {
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if (blkdone >= 0) {
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sn += blkdone;
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printf("%ld of ", (long)sn);
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}
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printf("%ld-%ld", (long)bp->bio_blkno,
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(long)(bp->bio_blkno + (bp->bio_bcount - 1) / DEV_BSIZE));
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}
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if (lp && (blkdone >= 0 || bp->bio_bcount <= lp->d_secsize)) {
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sn += lp->d_partitions[part].p_offset;
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/*
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* XXX should add slice offset and not print the slice,
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* but we don't know the slice pointer.
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* XXX should print bp->b_pblkno so that this will work
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* independent of slices, labels and bad sector remapping,
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* but some drivers don't set bp->b_pblkno.
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*/
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printf(" (%s bn %ld; cn %ld", sname, (long)sn,
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(long)(sn / lp->d_secpercyl));
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sn %= (long)lp->d_secpercyl;
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printf(" tn %ld sn %ld)", (long)(sn / lp->d_nsectors),
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(long)(sn % lp->d_nsectors));
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}
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}
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