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rumpuser_bio.c revision 1.2 
      1 /*	$NetBSD: rumpuser_bio.c,v 1.2 2013/04/29 13:53:46 pooka Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2013 Antti Kantee.  All Rights Reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
     16  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     18  * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     21  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     25  * SUCH DAMAGE.
     26  */
     27 
     28 #include "rumpuser_port.h"
     29 
     30 #include <sys/types.h>
     31 
     32 #include <assert.h>
     33 #include <errno.h>
     34 #include <pthread.h>
     35 #include <stdio.h>
     36 #include <string.h>
     37 #include <unistd.h>
     38 
     39 #include <rump/rumpuser.h>
     40 
     41 #include "rumpuser_int.h"
     42 
     43 struct rumpuser_bio {
     44 	int bio_fd;
     45 	int bio_op;
     46 	void *bio_data;
     47 	size_t bio_dlen;
     48 	off_t bio_off;
     49 
     50 	rump_biodone_fn bio_done;
     51 	void *bio_donearg;
     52 };
     53 
     54 #define N_BIOS 128
     55 static pthread_mutex_t biomtx = PTHREAD_MUTEX_INITIALIZER;
     56 static pthread_cond_t biocv = PTHREAD_COND_INITIALIZER;
     57 static int bio_head, bio_tail;
     58 static struct rumpuser_bio bios[N_BIOS];
     59 
     60 static void
     61 dobio(struct rumpuser_bio *biop)
     62 {
     63 	ssize_t rv;
     64 	int error, dummy;
     65 
     66 	assert(biop->bio_donearg != NULL);
     67 	if (biop->bio_op & RUMPUSER_BIO_READ) {
     68 		error = 0;
     69 		rv = pread(biop->bio_fd, biop->bio_data,
     70 		    biop->bio_dlen, biop->bio_off);
     71 		if (rv < 0) {
     72 			rv = 0;
     73 			error = errno;
     74 		}
     75 	} else {
     76 		error = 0;
     77 		rv = pwrite(biop->bio_fd, biop->bio_data,
     78 		    biop->bio_dlen, biop->bio_off);
     79 		if (rv < 0) {
     80 			rv = 0;
     81 			error = errno;
     82 		} else if (biop->bio_op & RUMPUSER_BIO_SYNC) {
     83 #ifdef __NetBSD__
     84 			fsync_range(biop->bio_fd, FDATASYNC,
     85 			    biop->bio_off, biop->bio_dlen);
     86 #else
     87 			fsync(biop->bio_fd);
     88 #endif
     89 		}
     90 	}
     91 	rumpuser__reschedule(0, NULL);
     92 	biop->bio_done(biop->bio_donearg, (size_t)rv, error);
     93 	rumpuser__unschedule(0, &dummy, NULL);
     94 
     95 	/* paranoia */
     96 	biop->bio_donearg = NULL;
     97 }
     98 
     99 static void *
    100 biothread(void *arg)
    101 {
    102 	struct rumpuser_bio *biop;
    103 
    104 	NOFAIL_ERRNO(pthread_mutex_lock(&biomtx));
    105 	for (;;) {
    106 		while (bio_head == bio_tail)
    107 			NOFAIL_ERRNO(pthread_cond_wait(&biocv, &biomtx));
    108 
    109 		biop = &bios[bio_tail];
    110 		pthread_mutex_unlock(&biomtx);
    111 
    112 		dobio(biop);
    113 
    114 		NOFAIL_ERRNO(pthread_mutex_lock(&biomtx));
    115 		bio_tail = (bio_tail+1) % N_BIOS;
    116 		pthread_cond_signal(&biocv);
    117 	}
    118 
    119 	/* unreachable */
    120 	abort();
    121 }
    122 
    123 void
    124 rumpuser_bio(int fd, int op, void *data, size_t dlen, off_t doff,
    125 	rump_biodone_fn biodone, void *bioarg)
    126 {
    127 	struct rumpuser_bio bio;
    128 	static int inited = 0;
    129 	static int usethread = 0;
    130 	int nlocks;
    131 
    132 	rumpuser__unschedule(0, &nlocks, NULL);
    133 
    134 	if (!inited) {
    135 		pthread_mutex_lock(&biomtx);
    136 		if (!inited) {
    137 			char buf[16];
    138 			pthread_t pt;
    139 
    140 			/*
    141 			 * duplicates policy of rump kernel.  maybe a bit
    142 			 * questionable, but since the setting is not
    143 			 * used in normal circumstances, let's not care
    144 			 */
    145 			if (getenv_r("RUMP_THREADS", buf, sizeof(buf)) == 0)
    146 				usethread = *buf != '0';
    147 
    148 			pthread_create(&pt, NULL, biothread, NULL);
    149 			inited = 1;
    150 		}
    151 		pthread_mutex_unlock(&biomtx);
    152 		assert(inited);
    153 	}
    154 
    155 	bio.bio_fd = fd;
    156 	bio.bio_op = op;
    157 	bio.bio_data = data;
    158 	bio.bio_dlen = dlen;
    159 	bio.bio_off = doff;
    160 	bio.bio_done = biodone;
    161 	bio.bio_donearg = bioarg;
    162 
    163 	if (!usethread) {
    164 		dobio(&bio);
    165 	} else {
    166 		pthread_mutex_lock(&biomtx);
    167 		while ((bio_head+1) % N_BIOS == bio_tail)
    168 			pthread_cond_wait(&biocv, &biomtx);
    169 
    170 		bios[bio_head] = bio;
    171 		bio_head = (bio_head+1) % N_BIOS;
    172 
    173 		pthread_cond_signal(&biocv);
    174 		pthread_mutex_unlock(&biomtx);
    175 	}
    176 
    177 	rumpuser__reschedule(nlocks, NULL);
    178 }
    179