ae34b6ff96
for limiting disk (actually filesystem) IO. Note that in some cases these limits are not quite precise. It's ok, as long as it's within some reasonable bounds. Testing - and review of the code, in particular the VFS and VM parts - is very welcome. MFC after: 1 month Relnotes: yes Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D5080
226 lines
6.1 KiB
C
226 lines
6.1 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/malloc.h>
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#include <sys/proc.h>
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#include <sys/racct.h>
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#include <sys/uio.h>
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#include <geom/geom.h>
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#include <vm/vm.h>
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#include <vm/vm_page.h>
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#include <vm/vm_extern.h>
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#include <vm/vm_map.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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struct cdevsw *csw;
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struct buf *pbuf;
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struct bio *bp;
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struct vm_page **pages;
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caddr_t sa;
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u_int iolen, poff;
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int error, i, npages, maxpages;
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vm_prot_t prot;
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csw = dev->si_devsw;
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/* check if character device is being destroyed */
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if (csw == NULL)
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return (ENXIO);
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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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/*
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* If the driver does not want I/O to be split, that means that we
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* need to reject any requests that will not fit into one buffer.
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*/
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if (dev->si_flags & SI_NOSPLIT &&
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(uio->uio_resid > dev->si_iosize_max || uio->uio_resid > MAXPHYS ||
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uio->uio_iovcnt > 1)) {
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/*
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* Tell the user why his I/O was rejected.
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*/
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if (uio->uio_resid > dev->si_iosize_max)
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uprintf("%s: request size=%zd > si_iosize_max=%d; "
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"cannot split request\n", devtoname(dev),
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uio->uio_resid, dev->si_iosize_max);
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if (uio->uio_resid > MAXPHYS)
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uprintf("%s: request size=%zd > MAXPHYS=%d; "
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"cannot split request\n", devtoname(dev),
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uio->uio_resid, MAXPHYS);
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if (uio->uio_iovcnt > 1)
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uprintf("%s: request vectors=%d > 1; "
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"cannot split request\n", devtoname(dev),
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uio->uio_iovcnt);
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return (EFBIG);
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}
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/*
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* Keep the process UPAGES from being swapped. Processes swapped
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* out while holding pbufs, used by swapper, may lead to deadlock.
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*/
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PHOLD(curproc);
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bp = g_alloc_bio();
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if (uio->uio_segflg != UIO_USERSPACE) {
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pbuf = NULL;
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pages = NULL;
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} else if ((dev->si_flags & SI_UNMAPPED) && unmapped_buf_allowed) {
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pbuf = NULL;
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maxpages = btoc(MIN(uio->uio_resid, MAXPHYS)) + 1;
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pages = malloc(sizeof(*pages) * maxpages, M_DEVBUF, M_WAITOK);
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} else {
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pbuf = getpbuf(NULL);
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sa = pbuf->b_data;
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maxpages = btoc(MAXPHYS);
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pages = pbuf->b_pages;
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}
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prot = VM_PROT_READ;
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if (uio->uio_rw == UIO_READ)
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prot |= VM_PROT_WRITE; /* Less backwards than it looks */
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error = 0;
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for (i = 0; i < uio->uio_iovcnt; i++) {
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#ifdef RACCT
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if (racct_enable) {
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PROC_LOCK(curproc);
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if (uio->uio_rw == UIO_READ) {
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racct_add_force(curproc, RACCT_READBPS,
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uio->uio_iov[i].iov_len);
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racct_add_force(curproc, RACCT_READIOPS, 1);
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} else {
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racct_add_force(curproc, RACCT_WRITEBPS,
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uio->uio_iov[i].iov_len);
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racct_add_force(curproc, RACCT_WRITEIOPS, 1);
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}
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PROC_UNLOCK(curproc);
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}
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#endif /* RACCT */
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while (uio->uio_iov[i].iov_len) {
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g_reset_bio(bp);
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if (uio->uio_rw == UIO_READ) {
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bp->bio_cmd = BIO_READ;
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curthread->td_ru.ru_inblock++;
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} else {
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bp->bio_cmd = BIO_WRITE;
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curthread->td_ru.ru_oublock++;
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}
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bp->bio_offset = uio->uio_offset;
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bp->bio_data = uio->uio_iov[i].iov_base;
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bp->bio_length = uio->uio_iov[i].iov_len;
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if (bp->bio_length > dev->si_iosize_max)
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bp->bio_length = dev->si_iosize_max;
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if (bp->bio_length > MAXPHYS)
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bp->bio_length = MAXPHYS;
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/*
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* Make sure the pbuf can map the request.
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* The pbuf has kvasize = MAXPHYS, so a request
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* larger than MAXPHYS - PAGE_SIZE must be
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* page aligned or it will be fragmented.
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*/
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poff = (vm_offset_t)bp->bio_data & PAGE_MASK;
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if (pbuf && bp->bio_length + poff > pbuf->b_kvasize) {
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if (dev->si_flags & SI_NOSPLIT) {
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uprintf("%s: request ptr %p is not "
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"on a page boundary; cannot split "
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"request\n", devtoname(dev),
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bp->bio_data);
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error = EFBIG;
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goto doerror;
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}
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bp->bio_length = pbuf->b_kvasize;
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if (poff != 0)
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bp->bio_length -= PAGE_SIZE;
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}
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bp->bio_bcount = bp->bio_length;
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bp->bio_dev = dev;
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if (pages) {
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if ((npages = vm_fault_quick_hold_pages(
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&curproc->p_vmspace->vm_map,
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(vm_offset_t)bp->bio_data, bp->bio_length,
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prot, pages, maxpages)) < 0) {
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error = EFAULT;
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goto doerror;
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}
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if (pbuf) {
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pmap_qenter((vm_offset_t)sa,
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pages, npages);
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bp->bio_data = sa + poff;
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} else {
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bp->bio_ma = pages;
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bp->bio_ma_n = npages;
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bp->bio_ma_offset = poff;
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bp->bio_data = unmapped_buf;
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bp->bio_flags |= BIO_UNMAPPED;
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}
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}
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csw->d_strategy(bp);
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if (uio->uio_rw == UIO_READ)
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biowait(bp, "physrd");
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else
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biowait(bp, "physwr");
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if (pages) {
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if (pbuf)
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pmap_qremove((vm_offset_t)sa, npages);
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vm_page_unhold_pages(pages, npages);
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}
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iolen = bp->bio_length - bp->bio_resid;
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if (iolen == 0 && !(bp->bio_flags & 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->bio_flags & BIO_ERROR) {
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error = bp->bio_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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if (pbuf)
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relpbuf(pbuf, NULL);
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else if (pages)
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free(pages, M_DEVBUF);
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g_destroy_bio(bp);
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PRELE(curproc);
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return (error);
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}
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