31932fae1e
In physio, check if device can handle unmapped IO and pass an appropriately mapped buffer to the driver strategy routine. The only driver in the tree that can handle unmapped buffers is one exposed by GEOM, so mark it as such with the new flag in the driver cdevsw structure. This fixes insta-panics on hosts, running dconschat, as /dev/fwmem is an example of the driver that makes use of physio routine, but bypasses the g_down thread, where the buffer gets mapped normally. Discussed with: kib (earlier version)
137 lines
3.5 KiB
C
137 lines
3.5 KiB
C
/*-
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* Copyright (c) 1994 John S. Dyson
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* All rights reserved.
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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 immediately at the beginning of the file, without modification,
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* 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. Absolutely no warranty of function or purpose is made by the author
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* John S. Dyson.
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* 4. Modifications may be freely made to this file if the above conditions
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* are met.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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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/proc.h>
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#include <sys/uio.h>
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#include <vm/vm.h>
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#include <vm/vm_extern.h>
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int
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physio(struct cdev *dev, struct uio *uio, int ioflag)
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{
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int i;
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int error;
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caddr_t sa;
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u_int iolen;
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struct buf *bp;
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/* Keep the process UPAGES from being swapped. XXX: why ? */
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PHOLD(curproc);
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bp = getpbuf(NULL);
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sa = bp->b_data;
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error = 0;
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/* XXX: sanity check */
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if(dev->si_iosize_max < PAGE_SIZE) {
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printf("WARNING: %s si_iosize_max=%d, using DFLTPHYS.\n",
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devtoname(dev), dev->si_iosize_max);
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dev->si_iosize_max = DFLTPHYS;
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}
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for (i = 0; i < uio->uio_iovcnt; i++) {
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while (uio->uio_iov[i].iov_len) {
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bp->b_flags = 0;
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if (uio->uio_rw == UIO_READ) {
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bp->b_iocmd = BIO_READ;
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curthread->td_ru.ru_inblock++;
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} else {
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bp->b_iocmd = BIO_WRITE;
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curthread->td_ru.ru_oublock++;
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}
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bp->b_iodone = bdone;
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bp->b_data = uio->uio_iov[i].iov_base;
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bp->b_bcount = uio->uio_iov[i].iov_len;
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bp->b_offset = uio->uio_offset;
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bp->b_iooffset = uio->uio_offset;
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bp->b_saveaddr = sa;
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/* Don't exceed drivers iosize limit */
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if (bp->b_bcount > dev->si_iosize_max)
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bp->b_bcount = dev->si_iosize_max;
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/*
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* Make sure the pbuf can map the request
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* XXX: The pbuf has kvasize = MAXPHYS so a request
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* XXX: larger than MAXPHYS - PAGE_SIZE must be
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* XXX: page aligned or it will be fragmented.
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*/
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iolen = ((vm_offset_t) bp->b_data) & PAGE_MASK;
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if ((bp->b_bcount + iolen) > bp->b_kvasize) {
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bp->b_bcount = bp->b_kvasize;
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if (iolen != 0)
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bp->b_bcount -= PAGE_SIZE;
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}
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bp->b_bufsize = bp->b_bcount;
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bp->b_blkno = btodb(bp->b_offset);
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if (uio->uio_segflg == UIO_USERSPACE) {
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struct cdevsw *csw;
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int mapped;
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csw = dev->si_devsw;
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if (csw != NULL &&
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(csw->d_flags & D_UNMAPPED_IO) != 0)
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mapped = 0;
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else
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mapped = 1;
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if (vmapbuf(bp, mapped) < 0) {
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error = EFAULT;
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goto doerror;
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}
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}
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dev_strategy(dev, bp);
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if (uio->uio_rw == UIO_READ)
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bwait(bp, PRIBIO, "physrd");
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else
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bwait(bp, PRIBIO, "physwr");
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if (uio->uio_segflg == UIO_USERSPACE)
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vunmapbuf(bp);
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iolen = bp->b_bcount - bp->b_resid;
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if (iolen == 0 && !(bp->b_ioflags & BIO_ERROR))
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goto doerror; /* EOF */
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uio->uio_iov[i].iov_len -= iolen;
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uio->uio_iov[i].iov_base =
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(char *)uio->uio_iov[i].iov_base + iolen;
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uio->uio_resid -= iolen;
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uio->uio_offset += iolen;
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if( bp->b_ioflags & BIO_ERROR) {
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error = bp->b_error;
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goto doerror;
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}
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}
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}
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doerror:
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relpbuf(bp, NULL);
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PRELE(curproc);
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return (error);
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}
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