module/zfs/zfs_debug.c

   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  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
  23  * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
  24  */
  25
  26 #include <sys/zfs_context.h>
  27
  28 typedef struct zfs_dbgmsg {
  29         procfs_list_node_t      zdm_node;
  30         time_t                  zdm_timestamp;
  31         int                     zdm_size;
  32         char                    zdm_msg[1]; /* variable length allocation */
  33 } zfs_dbgmsg_t;
  34
  35 procfs_list_t zfs_dbgmsgs;
  36 int zfs_dbgmsg_size = 0;
  37 int zfs_dbgmsg_maxsize = 4<<20; /* 4MB */
  38
  39 /*
  40  * Internal ZFS debug messages are enabled by default.
  41  *
  42  * # Print debug messages
  43  * cat /proc/spl/kstat/zfs/dbgmsg
  44  *
  45  * # Disable the kernel debug message log.
  46  * echo 0 > /sys/module/zfs/parameters/zfs_dbgmsg_enable
  47  *
  48  * # Clear the kernel debug message log.
  49  * echo 0 >/proc/spl/kstat/zfs/dbgmsg
  50  */
  51 int zfs_dbgmsg_enable = 1;
  52
  53 static int
  54 zfs_dbgmsg_show_header(struct seq_file *f)
  55 {
  56         seq_printf(f, "%-12s %-8s\n", "timestamp", "message");
  57         return (0);
  58 }
  59
  60 static int
  61 zfs_dbgmsg_show(struct seq_file *f, void *p)
  62 {
  63         zfs_dbgmsg_t *zdm = (zfs_dbgmsg_t *)p;
  64         seq_printf(f, "%-12llu %-s\n",
  65             (u_longlong_t)zdm->zdm_timestamp, zdm->zdm_msg);
  66         return (0);
  67 }
  68
  69 static void
  70 zfs_dbgmsg_purge(int max_size)
  71 {
  72         while (zfs_dbgmsg_size > max_size) {
  73                 zfs_dbgmsg_t *zdm = list_remove_head(&zfs_dbgmsgs.pl_list);
  74                 if (zdm == NULL)
  75                         return;
  76
  77                 int size = zdm->zdm_size;
  78                 kmem_free(zdm, size);
  79                 zfs_dbgmsg_size -= size;
  80         }
  81 }
  82
  83 static int
  84 zfs_dbgmsg_clear(procfs_list_t *procfs_list)
  85 {
  86         mutex_enter(&zfs_dbgmsgs.pl_lock);
  87         zfs_dbgmsg_purge(0);
  88         mutex_exit(&zfs_dbgmsgs.pl_lock);
  89         return (0);
  90 }
  91
  92 void
  93 zfs_dbgmsg_init(void)
  94 {
  95         procfs_list_install("zfs",
  96             "dbgmsg",
  97             0600,
  98             &zfs_dbgmsgs,
  99             zfs_dbgmsg_show,
 100             zfs_dbgmsg_show_header,
 101             zfs_dbgmsg_clear,
 102             offsetof(zfs_dbgmsg_t, zdm_node));
 103 }
 104
 105 void
 106 zfs_dbgmsg_fini(void)
 107 {
 108         procfs_list_uninstall(&zfs_dbgmsgs);
 109         zfs_dbgmsg_purge(0);
 110
 111         /*
 112          * TODO - decide how to make this permanent
 113          */
 114 #ifdef _KERNEL
 115         procfs_list_destroy(&zfs_dbgmsgs);
 116 #endif
 117 }
 118
 119 void
 120 __set_error(const char *file, const char *func, int line, int err)
 121 {
 122         /*
 123          * To enable this:
 124          *
 125          * $ echo 512 >/sys/module/zfs/parameters/zfs_flags
 126          */
 127         if (zfs_flags & ZFS_DEBUG_SET_ERROR)
 128                 __dprintf(B_FALSE, file, func, line, "error %lu", err);
 129 }
 130
 131 void
 132 __zfs_dbgmsg(char *buf)
 133 {
 134         int size = sizeof (zfs_dbgmsg_t) + strlen(buf);
 135         zfs_dbgmsg_t *zdm = kmem_zalloc(size, KM_SLEEP);
 136         zdm->zdm_size = size;
 137         zdm->zdm_timestamp = gethrestime_sec();
 138         strcpy(zdm->zdm_msg, buf);
 139
 140         mutex_enter(&zfs_dbgmsgs.pl_lock);
 141         procfs_list_add(&zfs_dbgmsgs, zdm);
 142         zfs_dbgmsg_size += size;
 143         zfs_dbgmsg_purge(MAX(zfs_dbgmsg_maxsize, 0));
 144         mutex_exit(&zfs_dbgmsgs.pl_lock);
 145 }
 146
 147 #ifdef _KERNEL
 148
 149 void
 150 __dprintf(boolean_t dprint, const char *file, const char *func,
 151     int line, const char *fmt, ...)
 152 {
 153         const char *newfile;
 154         va_list adx;
 155         size_t size;
 156         char *buf;
 157         char *nl;
 158         int i;
 159         char *prefix = (dprint) ? "dprintf: " : "";
 160
 161         size = 1024;
 162         buf = kmem_alloc(size, KM_SLEEP);
 163
 164         /*
 165          * Get rid of annoying prefix to filename.
 166          */
 167         newfile = strrchr(file, '/');
 168         if (newfile != NULL) {
 169                 newfile = newfile + 1; /* Get rid of leading / */
 170         } else {
 171                 newfile = file;
 172         }
 173
 174         i = snprintf(buf, size, "%s%s:%d:%s(): ", prefix, newfile, line, func);
 175
 176         if (i < size) {
 177                 va_start(adx, fmt);
 178                 (void) vsnprintf(buf + i, size - i, fmt, adx);
 179                 va_end(adx);
 180         }
 181
 182         /*
 183          * Get rid of trailing newline for dprintf logs.
 184          */
 185         if (dprint && buf[0] != '\0') {
 186                 nl = &buf[strlen(buf) - 1];
 187                 if (*nl == '\n')
 188                         *nl = '\0';
 189         }
 190
 191         /*
 192          * To get this data enable the zfs__dprintf trace point as shown:
 193          *
 194          * # Enable zfs__dprintf tracepoint, clear the tracepoint ring buffer
 195          * $ echo 1 > /sys/kernel/debug/tracing/events/zfs/enable
 196          * $ echo 0 > /sys/kernel/debug/tracing/trace
 197          *
 198          * # Dump the ring buffer.
 199          * $ cat /sys/kernel/debug/tracing/trace
 200          */
 201         DTRACE_PROBE1(zfs__dprintf, char *, buf);
 202
 203         /*
 204          * To get this data:
 205          *
 206          * $ cat /proc/spl/kstat/zfs/dbgmsg
 207          *
 208          * To clear the buffer:
 209          * $ echo 0 > /proc/spl/kstat/zfs/dbgmsg
 210          */
 211         __zfs_dbgmsg(buf);
 212
 213         kmem_free(buf, size);
 214 }
 215
 216 #else
 217
 218 void
 219 zfs_dbgmsg_print(const char *tag)
 220 {
 221         ssize_t ret __attribute__((unused));
 222
 223         /*
 224          * We use write() in this function instead of printf()
 225          * so it is safe to call from a signal handler.
 226          */
 227         ret = write(STDOUT_FILENO, "ZFS_DBGMSG(", 11);
 228         ret = write(STDOUT_FILENO, tag, strlen(tag));
 229         ret = write(STDOUT_FILENO, ") START:\n", 9);
 230
 231         mutex_enter(&zfs_dbgmsgs.pl_lock);
 232         for (zfs_dbgmsg_t *zdm = list_head(&zfs_dbgmsgs.pl_list); zdm != NULL;
 233             zdm = list_next(&zfs_dbgmsgs.pl_list, zdm)) {
 234                 ret = write(STDOUT_FILENO, zdm->zdm_msg,
 235                     strlen(zdm->zdm_msg));
 236                 ret = write(STDOUT_FILENO, "\n", 1);
 237         }
 238
 239         ret = write(STDOUT_FILENO, "ZFS_DBGMSG(", 11);
 240         ret = write(STDOUT_FILENO, tag, strlen(tag));
 241         ret = write(STDOUT_FILENO, ") END\n", 6);
 242
 243         mutex_exit(&zfs_dbgmsgs.pl_lock);
 244 }
 245 #endif /* _KERNEL */
 246
 247 #ifdef _KERNEL
 248 module_param(zfs_dbgmsg_enable, int, 0644);
 249 MODULE_PARM_DESC(zfs_dbgmsg_enable, "Enable ZFS debug message log");
 250
 251 module_param(zfs_dbgmsg_maxsize, int, 0644);
 252 MODULE_PARM_DESC(zfs_dbgmsg_maxsize, "Maximum ZFS debug log size");
 253 #endif