1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 28 #include <sys/types.h> 29 #include <sys/stat.h> 30 #include <fcntl.h> 31 #include <pthread.h> 32 #include <string.h> 33 #include <stdio.h> 34 #include <unistd.h> 35 #include <stdlib.h> 36 #include <errno.h> 37 38 /* 39 * The size of the output file, "go.out", should be 80*8192*2 = 1310720 40 * 41 * $ cd /tmp; go; ls -l go.out 42 * done. 43 * -rwxr-xr-x 1 jdm staff 1310720 Apr 13 19:45 go.out 44 * $ cd /zfs; go; ls -l go.out 45 * done. 46 * -rwxr-xr-x 1 jdm staff 663552 Apr 13 19:45 go.out 47 * 48 * The file on zfs is short as it does not appear that zfs is making the 49 * implicit seek to EOF and the actual write atomic. From the SUSv3 50 * interface spec, behavior is undefined if concurrent writes are performed 51 * from multi-processes to a single file. So I don't know if this is a 52 * standards violation, but I cannot find any such disclaimers in our 53 * man pages. This issue came up at a customer site in another context, and 54 * the suggestion was to open the file with O_APPEND, but that wouldn't 55 * help with zfs(see 4977529). Also see bug# 5031301. 56 */ 57 58 static int outfd = 0; 59 60 static void * 61 go(void *data) 62 { 63 int i = 0, n = *(int *)data; 64 ssize_t ret = 0; 65 char buf[8192] = {0}; 66 (void) memset(buf, n, sizeof (buf)); 67 68 for (i = 0; i < 80; i++) { 69 ret = write(outfd, buf, sizeof (buf)); 70 } 71 return (NULL); 72 } 73 74 static void 75 usage() 76 { 77 (void) fprintf(stderr, 78 "usage: zfs_threadsappend <file name>\n"); 79 exit(1); 80 } 81 82 int 83 main(int argc, char **argv) 84 { 85 pthread_t threads[2]; 86 int ret = 0; 87 long ncpus = 0; 88 int i; 89 90 if (argc != 2) { 91 usage(); 92 } 93 94 ncpus = sysconf(_SC_NPROCESSORS_ONLN); 95 if (ncpus < 0) { 96 (void) fprintf(stderr, 97 "Invalid return from sysconf(_SC_NPROCESSORS_ONLN)" 98 " : errno (decimal)=%d\n", errno); 99 exit(1); 100 } 101 if (ncpus < 2) { 102 (void) fprintf(stderr, 103 "Must execute this binary on a multi-processor system\n"); 104 exit(1); 105 } 106 107 outfd = open(argv[optind++], O_RDWR|O_CREAT|O_APPEND|O_TRUNC, 0777); 108 if (outfd == -1) { 109 (void) fprintf(stderr, 110 "zfs_threadsappend: " 111 "open(%s, O_RDWR|O_CREAT|O_APPEND|O_TRUNC, 0777)" 112 " failed\n", argv[optind]); 113 perror("open"); 114 exit(1); 115 } 116 117 for (i = 0; i < 2; i++) { 118 ret = pthread_create(&threads[i], NULL, go, (void *)&i); 119 if (ret != 0) { 120 (void) fprintf(stderr, 121 "zfs_threadsappend: thr_create(#%d) " 122 "failed error=%d\n", i+1, ret); 123 exit(1); 124 } 125 } 126 127 for (i = 0; i < 2; i++) { 128 if (pthread_join(threads[i], NULL) != 0) 129 break; 130 } 131 132 return (0); 133 } 134