The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/dev/scsipi/st.c

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    1 /*      $NetBSD: st.c,v 1.194.2.1 2007/11/25 09:34:38 xtraeme Exp $ */
    2 
    3 /*-
    4  * Copyright (c) 1998, 2004 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by Charles M. Hannum.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *        This product includes software developed by the NetBSD
   21  *        Foundation, Inc. and its contributors.
   22  * 4. Neither the name of The NetBSD Foundation nor the names of its
   23  *    contributors may be used to endorse or promote products derived
   24  *    from this software without specific prior written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   36  * POSSIBILITY OF SUCH DAMAGE.
   37  */
   38 
   39 /*
   40  * Originally written by Julian Elischer (julian@tfs.com)
   41  * for TRW Financial Systems for use under the MACH(2.5) operating system.
   42  *
   43  * TRW Financial Systems, in accordance with their agreement with Carnegie
   44  * Mellon University, makes this software available to CMU to distribute
   45  * or use in any manner that they see fit as long as this message is kept with
   46  * the software. For this reason TFS also grants any other persons or
   47  * organisations permission to use or modify this software.
   48  *
   49  * TFS supplies this software to be publicly redistributed
   50  * on the understanding that TFS is not responsible for the correct
   51  * functioning of this software in any circumstances.
   52  *
   53  * Ported to run under 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
   54  * major changes by Julian Elischer (julian@jules.dialix.oz.au) May 1993
   55  *
   56  * A lot of rewhacking done by mjacob (mjacob@nas.nasa.gov).
   57  */
   58 
   59 #include <sys/cdefs.h>
   60 __KERNEL_RCSID(0, "$NetBSD: st.c,v 1.194.2.1 2007/11/25 09:34:38 xtraeme Exp $");
   61 
   62 #include "opt_scsi.h"
   63 
   64 #include <sys/param.h>
   65 #include <sys/systm.h>
   66 #include <sys/fcntl.h>
   67 #include <sys/errno.h>
   68 #include <sys/ioctl.h>
   69 #include <sys/malloc.h>
   70 #include <sys/buf.h>
   71 #include <sys/bufq.h>
   72 #include <sys/proc.h>
   73 #include <sys/user.h>
   74 #include <sys/mtio.h>
   75 #include <sys/device.h>
   76 #include <sys/conf.h>
   77 #include <sys/kernel.h>
   78 #include <sys/vnode.h>
   79 #include <sys/iostat.h>
   80 #include <sys/sysctl.h>
   81 
   82 #include <dev/scsipi/scsi_spc.h>
   83 #include <dev/scsipi/scsipi_all.h>
   84 #include <dev/scsipi/scsi_all.h>
   85 #include <dev/scsipi/scsi_tape.h>
   86 #include <dev/scsipi/scsipiconf.h>
   87 #include <dev/scsipi/scsipi_base.h>
   88 #include <dev/scsipi/stvar.h>
   89 
   90 /* Defines for device specific stuff */
   91 #define DEF_FIXED_BSIZE  512
   92 
   93 #define STMODE(z)       ( minor(z)       & 0x03)
   94 #define STDSTY(z)       ((minor(z) >> 2) & 0x03)
   95 #define STUNIT(z)       ((minor(z) >> 4)       )
   96 #define STNMINOR        16
   97 
   98 #define NORMAL_MODE     0
   99 #define NOREW_MODE      1
  100 #define EJECT_MODE      2
  101 #define CTRL_MODE       3
  102 
  103 #define FALSE           0
  104 #define TRUE            1
  105 
  106 #ifndef         ST_MOUNT_DELAY
  107 #define         ST_MOUNT_DELAY          0
  108 #endif
  109 
  110 static dev_type_open(stopen);
  111 static dev_type_close(stclose);
  112 static dev_type_read(stread);
  113 static dev_type_write(stwrite);
  114 static dev_type_ioctl(stioctl);
  115 static dev_type_strategy(ststrategy);
  116 static dev_type_dump(stdump);
  117 
  118 const struct bdevsw st_bdevsw = {
  119         stopen, stclose, ststrategy, stioctl, stdump, nosize, D_TAPE
  120 };
  121 
  122 const struct cdevsw st_cdevsw = {
  123         stopen, stclose, stread, stwrite, stioctl,
  124         nostop, notty, nopoll, nommap, nokqfilter, D_TAPE
  125 };
  126 
  127 /*
  128  * Define various devices that we know mis-behave in some way,
  129  * and note how they are bad, so we can correct for them
  130  */
  131 
  132 static const struct st_quirk_inquiry_pattern st_quirk_patterns[] = {
  133         {{T_SEQUENTIAL, T_REMOV,
  134          "        ", "                ", "    "}, {0, 0, {
  135                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 0-3 */
  136                 {ST_Q_FORCE_BLKSIZE, 512, QIC_24},      /* minor 4-7 */
  137                 {ST_Q_FORCE_BLKSIZE, 0, HALFINCH_1600}, /* minor 8-11 */
  138                 {ST_Q_FORCE_BLKSIZE, 0, HALFINCH_6250}  /* minor 12-15 */
  139         }}},
  140         {{T_SEQUENTIAL, T_REMOV,
  141          "TANDBERG", " TDC 3600       ", ""},     {0, 12, {
  142                 {0, 0, 0},                              /* minor 0-3 */
  143                 {ST_Q_FORCE_BLKSIZE, 0, QIC_525},       /* minor 4-7 */
  144                 {0, 0, QIC_150},                        /* minor 8-11 */
  145                 {0, 0, QIC_120}                         /* minor 12-15 */
  146         }}},
  147         {{T_SEQUENTIAL, T_REMOV,
  148          "TANDBERG", " TDC 3800       ", ""},     {0, 0, {
  149                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 0-3 */
  150                 {0, 0, QIC_525},                        /* minor 4-7 */
  151                 {0, 0, QIC_150},                        /* minor 8-11 */
  152                 {0, 0, QIC_120}                         /* minor 12-15 */
  153         }}},
  154         {{T_SEQUENTIAL, T_REMOV,
  155           "TANDBERG", " SLR5 4/8GB     ", ""},     {0, 0, {
  156                 {ST_Q_FORCE_BLKSIZE, 1024, 0},          /* minor 0-3 */
  157                 {0, 0, 0},                              /* minor 4-7 */
  158                 {0, 0, 0},                              /* minor 8-11 */
  159                 {0, 0, 0}                               /* minor 12-15 */
  160         }}},
  161         /*
  162          * lacking a manual for the 4200, it's not clear what the
  163          * specific density codes should be- the device is a 2.5GB
  164          * capable QIC drive, those density codes aren't readily
  165          * availabel. The 'default' will just have to do.
  166          */
  167         {{T_SEQUENTIAL, T_REMOV,
  168          "TANDBERG", " TDC 4200       ", ""},     {0, 0, {
  169                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 0-3 */
  170                 {0, 0, QIC_525},                        /* minor 4-7 */
  171                 {0, 0, QIC_150},                        /* minor 8-11 */
  172                 {0, 0, QIC_120}                         /* minor 12-15 */
  173         }}},
  174         /*
  175          * At least -005 and -007 need this.  I'll assume they all do unless I
  176          * hear otherwise.  - mycroft, 31MAR1994
  177          */
  178         {{T_SEQUENTIAL, T_REMOV,
  179          "ARCHIVE ", "VIPER 2525 25462", ""},     {0, 0, {
  180                 {ST_Q_SENSE_HELP, 0, 0},                /* minor 0-3 */
  181                 {ST_Q_SENSE_HELP, 0, QIC_525},          /* minor 4-7 */
  182                 {0, 0, QIC_150},                        /* minor 8-11 */
  183                 {0, 0, QIC_120}                         /* minor 12-15 */
  184         }}},
  185         /*
  186          * One user reports that this works for his tape drive.  It probably
  187          * needs more work.  - mycroft, 09APR1994
  188          */
  189         {{T_SEQUENTIAL, T_REMOV,
  190          "SANKYO  ", "CP525           ", ""},    {0, 0, {
  191                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 0-3 */
  192                 {ST_Q_FORCE_BLKSIZE, 512, QIC_525},     /* minor 4-7 */
  193                 {0, 0, QIC_150},                        /* minor 8-11 */
  194                 {0, 0, QIC_120}                         /* minor 12-15 */
  195         }}},
  196         {{T_SEQUENTIAL, T_REMOV,
  197          "ANRITSU ", "DMT780          ", ""},     {0, 0, {
  198                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 0-3 */
  199                 {ST_Q_FORCE_BLKSIZE, 512, QIC_525},     /* minor 4-7 */
  200                 {0, 0, QIC_150},                        /* minor 8-11 */
  201                 {0, 0, QIC_120}                         /* minor 12-15 */
  202         }}},
  203         {{T_SEQUENTIAL, T_REMOV,
  204          "ARCHIVE ", "VIPER 150  21247", ""},     {ST_Q_ERASE_NOIMM, 12, {
  205                 {ST_Q_SENSE_HELP, 0, 0},                /* minor 0-3 */
  206                 {0, 0, QIC_150},                        /* minor 4-7 */
  207                 {0, 0, QIC_120},                        /* minor 8-11 */
  208                 {0, 0, QIC_24}                          /* minor 12-15 */
  209         }}},
  210         {{T_SEQUENTIAL, T_REMOV,
  211          "ARCHIVE ", "VIPER 150  21531", ""},     {ST_Q_ERASE_NOIMM, 12, {
  212                 {ST_Q_SENSE_HELP, 0, 0},                /* minor 0-3 */
  213                 {0, 0, QIC_150},                        /* minor 4-7 */
  214                 {0, 0, QIC_120},                        /* minor 8-11 */
  215                 {0, 0, QIC_24}                          /* minor 12-15 */
  216         }}},
  217         {{T_SEQUENTIAL, T_REMOV,
  218          "WANGTEK ", "5099ES SCSI", ""},          {0, 0, {
  219                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 0-3 */
  220                 {0, 0, QIC_11},                         /* minor 4-7 */
  221                 {0, 0, QIC_24},                         /* minor 8-11 */
  222                 {0, 0, QIC_24}                          /* minor 12-15 */
  223         }}},
  224         {{T_SEQUENTIAL, T_REMOV,
  225          "WANGTEK ", "5150ES SCSI", ""},          {0, 0, {
  226                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 0-3 */
  227                 {0, 0, QIC_24},                         /* minor 4-7 */
  228                 {0, 0, QIC_120},                        /* minor 8-11 */
  229                 {0, 0, QIC_150}                         /* minor 12-15 */
  230         }}},
  231         {{T_SEQUENTIAL, T_REMOV,
  232          "WANGTEK ", "5525ES SCSI REV7", ""},     {0, 0, {
  233                 {0, 0, 0},                              /* minor 0-3 */
  234                 {ST_Q_BLKSIZE, 0, QIC_525},             /* minor 4-7 */
  235                 {0, 0, QIC_150},                        /* minor 8-11 */
  236                 {0, 0, QIC_120}                         /* minor 12-15 */
  237         }}},
  238         {{T_SEQUENTIAL, T_REMOV,
  239          "WangDAT ", "Model 1300      ", ""},     {0, 0, {
  240                 {0, 0, 0},                              /* minor 0-3 */
  241                 {ST_Q_FORCE_BLKSIZE, 512, DDS},         /* minor 4-7 */
  242                 {ST_Q_FORCE_BLKSIZE, 1024, DDS},        /* minor 8-11 */
  243                 {ST_Q_FORCE_BLKSIZE, 0, DDS}            /* minor 12-15 */
  244         }}},
  245         {{T_SEQUENTIAL, T_REMOV,
  246          "EXABYTE ", "EXB-8200        ", "263H"}, {0, 5, {
  247                 {0, 0, 0},                              /* minor 0-3 */
  248                 {0, 0, 0},                              /* minor 4-7 */
  249                 {0, 0, 0},                              /* minor 8-11 */
  250                 {0, 0, 0}                               /* minor 12-15 */
  251         }}},
  252         {{T_SEQUENTIAL, T_REMOV,
  253          "STK",      "9490",             ""},
  254                                 {ST_Q_FORCE_BLKSIZE, 0, {
  255                 {0, 0, 0},                              /* minor 0-3 */
  256                 {0, 0, 0},                              /* minor 4-7 */
  257                 {0, 0, 0},                              /* minor 8-11 */
  258                 {0, 0, 0}                               /* minor 12-15 */
  259         }}},
  260         {{T_SEQUENTIAL, T_REMOV,
  261          "STK",      "SD-3",             ""},
  262                                 {ST_Q_FORCE_BLKSIZE, 0, {
  263                 {0, 0, 0},                              /* minor 0-3 */
  264                 {0, 0, 0},                              /* minor 4-7 */
  265                 {0, 0, 0},                              /* minor 8-11 */
  266                 {0, 0, 0}                               /* minor 12-15 */
  267         }}},
  268         {{T_SEQUENTIAL, T_REMOV,
  269          "IBM",      "03590",            ""},     {ST_Q_IGNORE_LOADS, 0, {
  270                 {0, 0, 0},                              /* minor 0-3 */
  271                 {0, 0, 0},                              /* minor 4-7 */
  272                 {0, 0, 0},                              /* minor 8-11 */
  273                 {0, 0, 0}                               /* minor 12-15 */
  274         }}},
  275         {{T_SEQUENTIAL, T_REMOV,
  276          "HP      ", "T4000s          ", ""},     {ST_Q_UNIMODAL, 0, {
  277                 {0, 0, QIC_3095},                       /* minor 0-3 */
  278                 {0, 0, QIC_3095},                       /* minor 4-7 */
  279                 {0, 0, QIC_3095},                       /* minor 8-11 */
  280                 {0, 0, QIC_3095},                       /* minor 12-15 */
  281         }}},
  282 #if 0
  283         {{T_SEQUENTIAL, T_REMOV,
  284          "EXABYTE ", "EXB-8200        ", ""},     {0, 12, {
  285                 {0, 0, 0},                              /* minor 0-3 */
  286                 {0, 0, 0},                              /* minor 4-7 */
  287                 {0, 0, 0},                              /* minor 8-11 */
  288                 {0, 0, 0}                               /* minor 12-15 */
  289         }}},
  290 #endif
  291         {{T_SEQUENTIAL, T_REMOV,
  292          "TEAC    ", "MT-2ST/N50      ", ""},     {ST_Q_IGNORE_LOADS, 0, {
  293                 {0, 0, 0},                              /* minor 0-3 */
  294                 {0, 0, 0},                              /* minor 4-7 */
  295                 {0, 0, 0},                              /* minor 8-11 */
  296                 {0, 0, 0}                               /* minor 12-15 */
  297         }}},
  298         {{T_SEQUENTIAL, T_REMOV,
  299          "OnStream", "ADR50 Drive", ""},          {ST_Q_UNIMODAL, 0, {
  300                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 0-3 */
  301                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 4-7 */
  302                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 8-11 */
  303                 {ST_Q_FORCE_BLKSIZE, 512, 0},           /* minor 12-15 */
  304         }}},
  305         {{T_SEQUENTIAL, T_REMOV,
  306          "OnStream DI-30",      "",   "1.0"},  {ST_Q_NOFILEMARKS, 0, {
  307                 {0, 0, 0},                              /* minor 0-3 */
  308                 {0, 0, 0},                              /* minor 4-7 */
  309                 {0, 0, 0},                              /* minor 8-11 */
  310                 {0, 0, 0}                               /* minor 12-15 */
  311         }}},
  312         {{T_SEQUENTIAL, T_REMOV,
  313          "NCR H621", "0-STD-03-46F880 ", ""},     {ST_Q_NOPREVENT, 0, {
  314                 {0, 0, 0},                             /* minor 0-3 */
  315                 {0, 0, 0},                             /* minor 4-7 */
  316                 {0, 0, 0},                             /* minor 8-11 */
  317                 {0, 0, 0}                              /* minor 12-15 */
  318         }}},
  319 };
  320 
  321 #define NOEJECT 0
  322 #define EJECT 1
  323 
  324 static void     st_identify_drive(struct st_softc *,
  325                     struct scsipi_inquiry_pattern *);
  326 static void     st_loadquirks(struct st_softc *);
  327 static int      st_mount_tape(dev_t, int);
  328 static void     st_unmount(struct st_softc *, boolean);
  329 static int      st_decide_mode(struct st_softc *, boolean);
  330 static void     ststart(struct scsipi_periph *);
  331 static void     strestart(void *);
  332 static void     stdone(struct scsipi_xfer *, int);
  333 static int      st_read(struct st_softc *, char *, int, int);
  334 static int      st_space(struct st_softc *, int, u_int, int);
  335 static int      st_write_filemarks(struct st_softc *, int, int);
  336 static int      st_check_eod(struct st_softc *, boolean, int *, int);
  337 static int      st_load(struct st_softc *, u_int, int);
  338 static int      st_rewind(struct st_softc *, u_int, int);
  339 static int      st_interpret_sense(struct scsipi_xfer *);
  340 static int      st_touch_tape(struct st_softc *);
  341 static int      st_erase(struct st_softc *, int full, int flags);
  342 static int      st_rdpos(struct st_softc *, int, u_int32_t *);
  343 static int      st_setpos(struct st_softc *, int, u_int32_t *);
  344 
  345 static const struct scsipi_periphsw st_switch = {
  346         st_interpret_sense,
  347         ststart,
  348         NULL,
  349         stdone
  350 };
  351 
  352 #if     defined(ST_ENABLE_EARLYWARN)
  353 #define ST_INIT_FLAGS   ST_EARLYWARN
  354 #else
  355 #define ST_INIT_FLAGS   0
  356 #endif
  357 
  358 /*
  359  * The routine called by the low level scsi routine when it discovers
  360  * A device suitable for this driver
  361  */
  362 void
  363 stattach(struct device *parent, struct st_softc *st, void *aux)
  364 {
  365         struct scsipibus_attach_args *sa = aux;
  366         struct scsipi_periph *periph = sa->sa_periph;
  367 
  368         SC_DEBUG(periph, SCSIPI_DB2, ("stattach: "));
  369 
  370         /*
  371          * Store information needed to contact our base driver
  372          */
  373         st->sc_periph = periph;
  374         periph->periph_dev = &st->sc_dev;
  375         periph->periph_switch = &st_switch;
  376 
  377         /*
  378          * Set initial flags
  379          */
  380 
  381         st->flags = ST_INIT_FLAGS;
  382 
  383         /*
  384          * Set up the buf queue for this device
  385          */
  386         bufq_alloc(&st->buf_queue, "fcfs", 0);
  387 
  388         callout_init(&st->sc_callout);
  389 
  390         /*
  391          * Check if the drive is a known criminal and take
  392          * Any steps needed to bring it into line
  393          */
  394         st_identify_drive(st, &sa->sa_inqbuf);
  395         /*
  396          * Use the subdriver to request information regarding the drive.
  397          */
  398         printf("\n");
  399         printf("%s: %s", st->sc_dev.dv_xname, st->quirkdata ? "quirks apply, " : "");
  400         if (scsipi_test_unit_ready(periph,
  401             XS_CTL_DISCOVERY | XS_CTL_SILENT | XS_CTL_IGNORE_MEDIA_CHANGE) ||
  402             st->ops(st, ST_OPS_MODESENSE,
  403             XS_CTL_DISCOVERY | XS_CTL_SILENT | XS_CTL_IGNORE_MEDIA_CHANGE))
  404                 printf("drive empty\n");
  405         else {
  406                 printf("density code %d, ", st->media_density);
  407                 if (st->media_blksize > 0)
  408                         printf("%d-byte", st->media_blksize);
  409                 else
  410                         printf("variable");
  411                 printf(" blocks, write-%s\n",
  412                     (st->flags & ST_READONLY) ? "protected" : "enabled");
  413         }
  414 
  415         st->stats = iostat_alloc(IOSTAT_TAPE, parent, st->sc_dev.dv_xname);
  416 
  417 #if NRND > 0
  418         rnd_attach_source(&st->rnd_source, st->sc_dev.dv_xname,
  419                           RND_TYPE_TAPE, 0);
  420 #endif
  421 }
  422 
  423 int
  424 stactivate(struct device *self, enum devact act)
  425 {
  426         int rv = 0;
  427 
  428         switch (act) {
  429         case DVACT_ACTIVATE:
  430                 rv = EOPNOTSUPP;
  431                 break;
  432 
  433         case DVACT_DEACTIVATE:
  434                 /*
  435                  * Nothing to do; we key off the device's DVF_ACTIVE.
  436                  */
  437                 break;
  438         }
  439         return (rv);
  440 }
  441 
  442 int
  443 stdetach(struct device *self, int flags)
  444 {
  445         struct st_softc *st = device_private(self);
  446         int s, bmaj, cmaj, mn;
  447 
  448         /* locate the major number */
  449         bmaj = bdevsw_lookup_major(&st_bdevsw);
  450         cmaj = cdevsw_lookup_major(&st_cdevsw);
  451 
  452         /* kill any pending restart */
  453         callout_stop(&st->sc_callout);
  454 
  455         s = splbio();
  456 
  457         /* Kill off any queued buffers. */
  458         bufq_drain(st->buf_queue);
  459 
  460         bufq_free(st->buf_queue);
  461 
  462         /* Kill off any pending commands. */
  463         scsipi_kill_pending(st->sc_periph);
  464 
  465         splx(s);
  466 
  467         /* Nuke the vnodes for any open instances */
  468         mn = STUNIT(device_unit(self));
  469         vdevgone(bmaj, mn, mn+STNMINOR-1, VBLK);
  470         vdevgone(cmaj, mn, mn+STNMINOR-1, VCHR);
  471 
  472         iostat_free(st->stats);
  473 
  474 #if NRND > 0
  475         /* Unhook the entropy source. */
  476         rnd_detach_source(&st->rnd_source);
  477 #endif
  478 
  479         return (0);
  480 }
  481 
  482 /*
  483  * Use the inquiry routine in 'scsi_base' to get drive info so we can
  484  * Further tailor our behaviour.
  485  */
  486 static void
  487 st_identify_drive(struct st_softc *st, struct scsipi_inquiry_pattern *inqbuf)
  488 {
  489         const struct st_quirk_inquiry_pattern *finger;
  490         int priority;
  491 
  492         finger = scsipi_inqmatch(inqbuf,
  493             st_quirk_patterns,
  494             sizeof(st_quirk_patterns) / sizeof(st_quirk_patterns[0]),
  495             sizeof(st_quirk_patterns[0]), &priority);
  496         if (priority != 0) {
  497                 st->quirkdata = &finger->quirkdata;
  498                 st->drive_quirks = finger->quirkdata.quirks;
  499                 st->quirks = finger->quirkdata.quirks;  /* start value */
  500                 st->page_0_size = finger->quirkdata.page_0_size;
  501                 st_loadquirks(st);
  502         }
  503 }
  504 
  505 /*
  506  * initialise the subdevices to the default (QUIRK) state.
  507  * this will remove any setting made by the system operator or previous
  508  * operations.
  509  */
  510 static void
  511 st_loadquirks(struct st_softc *st)
  512 {
  513         int i;
  514         const struct    modes *mode;
  515         struct  modes *mode2;
  516 
  517         mode = st->quirkdata->modes;
  518         mode2 = st->modes;
  519         for (i = 0; i < 4; i++) {
  520                 memset(mode2, 0, sizeof(struct modes));
  521                 st->modeflags[i] &= ~(BLKSIZE_SET_BY_QUIRK |
  522                     DENSITY_SET_BY_QUIRK | BLKSIZE_SET_BY_USER |
  523                     DENSITY_SET_BY_USER);
  524                 if ((mode->quirks | st->drive_quirks) & ST_Q_FORCE_BLKSIZE) {
  525                         mode2->blksize = mode->blksize;
  526                         st->modeflags[i] |= BLKSIZE_SET_BY_QUIRK;
  527                 }
  528                 if (mode->density) {
  529                         mode2->density = mode->density;
  530                         st->modeflags[i] |= DENSITY_SET_BY_QUIRK;
  531                 }
  532                 mode2->quirks |= mode->quirks;
  533                 mode++;
  534                 mode2++;
  535         }
  536 }
  537 
  538 /*
  539  * open the device.
  540  */
  541 static int
  542 stopen(dev_t dev, int flags, int mode, struct lwp *l)
  543 {
  544         u_int stmode, dsty;
  545         int error, sflags, unit, tries, ntries;
  546         struct st_softc *st;
  547         struct scsipi_periph *periph;
  548         struct scsipi_adapter *adapt;
  549 
  550         unit = STUNIT(dev);
  551         if (unit >= st_cd.cd_ndevs)
  552                 return (ENXIO);
  553         st = st_cd.cd_devs[unit];
  554         if (st == NULL)
  555                 return (ENXIO);
  556 
  557         stmode = STMODE(dev);
  558         dsty = STDSTY(dev);
  559 
  560         periph = st->sc_periph;
  561         adapt = periph->periph_channel->chan_adapter;
  562 
  563         SC_DEBUG(periph, SCSIPI_DB1, ("open: dev=0x%x (unit %d (of %d))\n", dev,
  564             unit, st_cd.cd_ndevs));
  565 
  566 
  567         /*
  568          * Only allow one at a time
  569          */
  570         if (periph->periph_flags & PERIPH_OPEN) {
  571                 printf("%s: already open\n", st->sc_dev.dv_xname);
  572                 return (EBUSY);
  573         }
  574 
  575         if ((error = scsipi_adapter_addref(adapt)) != 0)
  576                 return (error);
  577 
  578         /*
  579          * clear any latched errors.
  580          */
  581         st->mt_resid = 0;
  582         st->mt_erreg = 0;
  583         st->asc = 0;
  584         st->ascq = 0;
  585 
  586         /*
  587          * Catch any unit attention errors. Be silent about this
  588          * unless we're already mounted. We ignore media change
  589          * if we're in control mode or not mounted yet.
  590          */
  591         if ((st->flags & ST_MOUNTED) == 0 || stmode == CTRL_MODE) {
  592 #ifdef SCSIDEBUG
  593                 sflags = XS_CTL_IGNORE_MEDIA_CHANGE;
  594 #else
  595                 sflags = XS_CTL_SILENT|XS_CTL_IGNORE_MEDIA_CHANGE;
  596 #endif
  597         } else
  598                 sflags = 0;
  599 
  600         /*
  601          * If we're already mounted or we aren't configured for
  602          * a mount delay, only try a test unit ready once. Otherwise,
  603          * try up to ST_MOUNT_DELAY times with a rest interval of
  604          * one second between each try.
  605          */
  606 
  607         if ((st->flags & ST_MOUNTED) || ST_MOUNT_DELAY == 0) {
  608                 ntries = 1;
  609         } else {
  610                 ntries = ST_MOUNT_DELAY;
  611         }
  612 
  613         for (error = tries = 0; tries < ntries; tries++) {
  614                 int slpintr, oflags;
  615 
  616                 /*
  617                  * If we had no error, or we're opening the control mode
  618                  * device, we jump out right away.
  619                  */
  620 
  621                 error = scsipi_test_unit_ready(periph, sflags);
  622                 if (error == 0 || stmode == CTRL_MODE) {
  623                         break;
  624                 }
  625 
  626                 /*
  627                  * We had an error.
  628                  *
  629                  * If we're already mounted or we aren't configured for
  630                  * a mount delay, or the error isn't a NOT READY error,
  631                  * skip to the error exit now.
  632                  */
  633                 if ((st->flags & ST_MOUNTED) || ST_MOUNT_DELAY == 0 ||
  634                     (st->mt_key != SKEY_NOT_READY)) {
  635                         goto bad;
  636                 }
  637 
  638                 /*
  639                  * clear any latched errors.
  640                  */
  641                 st->mt_resid = 0;
  642                 st->mt_erreg = 0;
  643                 st->asc = 0;
  644                 st->ascq = 0;
  645 
  646                 /*
  647                  * Fake that we have the device open so
  648                  * we block other apps from getting in.
  649                  */
  650 
  651                 oflags = periph->periph_flags;
  652                 periph->periph_flags |= PERIPH_OPEN;
  653 
  654                 slpintr = tsleep(&lbolt, PUSER|PCATCH, "stload", 0);
  655 
  656                 periph->periph_flags = oflags;  /* restore flags */
  657                 if (slpintr) {
  658                         goto bad;
  659                 }
  660         }
  661 
  662 
  663         /*
  664          * If the mode is 3 (e.g. minor = 3,7,11,15) then the device has
  665          * been opened to set defaults and perform other, usually non-I/O
  666          * related, operations. In this case, do a quick check to see
  667          * whether the unit actually had a tape loaded (this will be known
  668          * as to whether or not we got a NOT READY for the above
  669          * unit attention). If a tape is there, go do a mount sequence.
  670          */
  671         if (stmode == CTRL_MODE && st->mt_key == SKEY_NOT_READY) {
  672                 periph->periph_flags |= PERIPH_OPEN;
  673                 return (0);
  674         }
  675 
  676         /*
  677          * If we get this far and had an error set, that means we failed
  678          * to pass the 'test unit ready' test for the non-controlmode device,
  679          * so we bounce the open.
  680          */
  681 
  682         if (error)
  683                 return (error);
  684 
  685         /*
  686          * Else, we're now committed to saying we're open.
  687          */
  688 
  689         periph->periph_flags |= PERIPH_OPEN; /* unit attn are now errors */
  690 
  691         /*
  692          * If it's a different mode, or if the media has been
  693          * invalidated, unmount the tape from the previous
  694          * session but continue with open processing
  695          */
  696         if (st->last_dsty != dsty ||
  697             (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0)
  698                 st_unmount(st, NOEJECT);
  699 
  700         /*
  701          * If we are not mounted, then we should start a new
  702          * mount session.
  703          */
  704         if (!(st->flags & ST_MOUNTED)) {
  705                 if ((error = st_mount_tape(dev, flags)) != 0)
  706                         goto bad;
  707                 st->last_dsty = dsty;
  708         }
  709         if (!(st->quirks & ST_Q_NOPREVENT)) {
  710                 scsipi_prevent(periph, SPAMR_PREVENT_DT,
  711                     XS_CTL_IGNORE_ILLEGAL_REQUEST | XS_CTL_IGNORE_NOT_READY);
  712         }
  713 
  714         SC_DEBUG(periph, SCSIPI_DB2, ("open complete\n"));
  715         return (0);
  716 
  717 bad:
  718         st_unmount(st, NOEJECT);
  719         scsipi_adapter_delref(adapt);
  720         periph->periph_flags &= ~PERIPH_OPEN;
  721         return (error);
  722 }
  723 
  724 /*
  725  * close the device.. only called if we are the LAST
  726  * occurence of an open device
  727  */
  728 static int
  729 stclose(dev_t dev, int flags, int mode, struct lwp *l)
  730 {
  731         int stxx, error = 0;
  732         struct st_softc *st = st_cd.cd_devs[STUNIT(dev)];
  733         struct scsipi_periph *periph = st->sc_periph;
  734         struct scsipi_adapter *adapt = periph->periph_channel->chan_adapter;
  735 
  736         SC_DEBUG(st->sc_periph, SCSIPI_DB1, ("closing\n"));
  737 
  738         /*
  739          * Make sure that a tape opened in write-only mode will have
  740          * file marks written on it when closed, even if not written to.
  741          *
  742          * This is for SUN compatibility. Actually, the Sun way of
  743          * things is to:
  744          *
  745          *      only write filemarks if there are fmks to be written and
  746          *              - open for write (possibly read/write)
  747          *              - the last operation was a write
  748          *      or:
  749          *              - opened for wronly
  750          *              - no data was written (including filemarks)
  751          */
  752 
  753         stxx = st->flags & (ST_WRITTEN | ST_FM_WRITTEN);
  754         if (((flags & FWRITE) && stxx == ST_WRITTEN) ||
  755             ((flags & O_ACCMODE) == FWRITE && stxx == 0)) {
  756                 int nm;
  757                 error = st_check_eod(st, FALSE, &nm, 0);
  758         }
  759 
  760         /*
  761          * Allow robots to eject tape if needed.
  762          */
  763         scsipi_prevent(periph, SPAMR_ALLOW,
  764             XS_CTL_IGNORE_ILLEGAL_REQUEST | XS_CTL_IGNORE_NOT_READY);
  765 
  766         switch (STMODE(dev)) {
  767         case NORMAL_MODE:
  768                 st_unmount(st, NOEJECT);
  769                 break;
  770         case NOREW_MODE:
  771         case CTRL_MODE:
  772                 /*
  773                  * Leave mounted unless media seems to have been removed.
  774                  *
  775                  * Otherwise, if we're to terminate a tape with more than one
  776                  * filemark [ and because we're not rewinding here ], backspace
  777                  * one filemark so that later appends will see an unbroken
  778                  * sequence of:
  779                  *
  780                  *      file - FMK - file - FMK ... file - FMK FMK (EOM)
  781                  */
  782                 if ((periph->periph_flags & PERIPH_MEDIA_LOADED) == 0) {
  783                         st_unmount(st, NOEJECT);
  784                 } else if (error == 0) {
  785                         /*
  786                          * ST_WRITTEN was preserved from above.
  787                          *
  788                          * All we need to know here is:
  789                          *
  790                          *      Were we writing this tape and was the last
  791                          *      operation a write?
  792                          *
  793                          *      Are there supposed to be 2FM at EOD?
  794                          *
  795                          * If both statements are true, then we backspace
  796                          * one filemark.
  797                          */
  798                         stxx |= (st->flags & ST_2FM_AT_EOD);
  799                         if ((flags & FWRITE) != 0 &&
  800                             (stxx == (ST_2FM_AT_EOD|ST_WRITTEN))) {
  801                                 error = st_space(st, -1, SP_FILEMARKS, 0);
  802                         }
  803                 }
  804                 break;
  805         case EJECT_MODE:
  806                 st_unmount(st, EJECT);
  807                 break;
  808         }
  809 
  810         scsipi_wait_drain(periph);
  811 
  812         scsipi_adapter_delref(adapt);
  813         periph->periph_flags &= ~PERIPH_OPEN;
  814 
  815         return (error);
  816 }
  817 
  818 /*
  819  * Start a new mount session.
  820  * Copy in all the default parameters from the selected device mode.
  821  * and try guess any that seem to be defaulted.
  822  */
  823 static int
  824 st_mount_tape(dev_t dev, int flags)
  825 {
  826         int unit;
  827         u_int dsty;
  828         struct st_softc *st;
  829         struct scsipi_periph *periph;
  830         int error = 0;
  831 
  832         unit = STUNIT(dev);
  833         dsty = STDSTY(dev);
  834         st = st_cd.cd_devs[unit];
  835         periph = st->sc_periph;
  836 
  837         if (st->flags & ST_MOUNTED)
  838                 return (0);
  839 
  840         SC_DEBUG(periph, SCSIPI_DB1, ("mounting\n "));
  841         st->flags |= ST_NEW_MOUNT;
  842         st->quirks = st->drive_quirks | st->modes[dsty].quirks;
  843         /*
  844          * If the media is new, then make sure we give it a chance to
  845          * to do a 'load' instruction.  (We assume it is new.)
  846          */
  847         if ((error = st_load(st, LD_LOAD, XS_CTL_SILENT)) != 0)
  848                 return (error);
  849         /*
  850          * Throw another dummy instruction to catch
  851          * 'Unit attention' errors. Many drives give
  852          * these after doing a Load instruction (with
  853          * the MEDIUM MAY HAVE CHANGED asc/ascq).
  854          */
  855         scsipi_test_unit_ready(periph, XS_CTL_SILENT);  /* XXX */
  856 
  857         /*
  858          * Some devices can't tell you much until they have been
  859          * asked to look at the media. This quirk does this.
  860          */
  861         if (st->quirks & ST_Q_SENSE_HELP)
  862                 if ((error = st_touch_tape(st)) != 0)
  863                         return (error);
  864         /*
  865          * Load the physical device parameters
  866          * loads: blkmin, blkmax
  867          */
  868         if ((error = st->ops(st, ST_OPS_RBL, 0)) != 0)
  869                 return (error);
  870         /*
  871          * Load the media dependent parameters
  872          * includes: media_blksize,media_density,numblks
  873          * As we have a tape in, it should be reflected here.
  874          * If not you may need the "quirk" above.
  875          */
  876         if ((error = st->ops(st, ST_OPS_MODESENSE, 0)) != 0)
  877                 return (error);
  878         /*
  879          * If we have gained a permanent density from somewhere,
  880          * then use it in preference to the one supplied by
  881          * default by the driver.
  882          */
  883         if (st->modeflags[dsty] & (DENSITY_SET_BY_QUIRK | DENSITY_SET_BY_USER))
  884                 st->density = st->modes[dsty].density;
  885         else
  886                 st->density = st->media_density;
  887         /*
  888          * If we have gained a permanent blocksize
  889          * then use it in preference to the one supplied by
  890          * default by the driver.
  891          */
  892         st->flags &= ~ST_FIXEDBLOCKS;
  893         if (st->modeflags[dsty] &
  894             (BLKSIZE_SET_BY_QUIRK | BLKSIZE_SET_BY_USER)) {
  895                 st->blksize = st->modes[dsty].blksize;
  896                 if (st->blksize)
  897                         st->flags |= ST_FIXEDBLOCKS;
  898         } else {
  899                 if ((error = st_decide_mode(st, FALSE)) != 0)
  900                         return (error);
  901         }
  902         if ((error = st->ops(st, ST_OPS_MODESELECT, 0)) != 0) {
  903                 /* ATAPI will return ENODEV for this, and this may be OK */
  904                 if (error != ENODEV) {
  905                         printf("%s: cannot set selected mode\n",
  906                             st->sc_dev.dv_xname);
  907                         return (error);
  908                 }
  909         }
  910         st->flags &= ~ST_NEW_MOUNT;
  911         st->flags |= ST_MOUNTED;
  912         periph->periph_flags |= PERIPH_MEDIA_LOADED;    /* move earlier? */
  913         st->blkno = st->fileno = (daddr_t) 0;
  914         return (0);
  915 }
  916 
  917 /*
  918  * End the present mount session.
  919  * Rewind, and optionally eject the tape.
  920  * Reset various flags to indicate that all new
  921  * operations require another mount operation
  922  */
  923 static void
  924 st_unmount(struct st_softc *st, boolean eject)
  925 {
  926         struct scsipi_periph *periph = st->sc_periph;
  927         int nmarks;
  928 
  929         if ((st->flags & ST_MOUNTED) == 0)
  930                 return;
  931         SC_DEBUG(periph, SCSIPI_DB1, ("unmounting\n"));
  932         st_check_eod(st, FALSE, &nmarks, XS_CTL_IGNORE_NOT_READY);
  933         st_rewind(st, 0, XS_CTL_IGNORE_NOT_READY);
  934 
  935         /*
  936          * Section 9.3.3 of the SCSI specs states that a device shall return
  937          * the density value specified in the last succesfull MODE SELECT
  938          * after an unload operation, in case it is not able to
  939          * automatically determine the density of the new medium.
  940          *
  941          * So we instruct the device to use the default density, which will
  942          * prevent the use of stale density values (in particular,
  943          * in st_touch_tape().
  944          */
  945         st->density = 0;
  946         if (st->ops(st, ST_OPS_MODESELECT, 0) != 0) {
  947                 printf("%s: WARNING: cannot revert to default density\n",
  948                         st->sc_dev.dv_xname);
  949         }
  950 
  951         if (eject) {
  952                 if (!(st->quirks & ST_Q_NOPREVENT)) {
  953                         scsipi_prevent(periph, SPAMR_ALLOW,
  954                             XS_CTL_IGNORE_ILLEGAL_REQUEST |
  955                             XS_CTL_IGNORE_NOT_READY);
  956                 }
  957                 st_load(st, LD_UNLOAD, XS_CTL_IGNORE_NOT_READY);
  958                 st->blkno = st->fileno = (daddr_t) -1;
  959         } else {
  960                 st->blkno = st->fileno = (daddr_t) 0;
  961         }
  962         st->flags &= ~(ST_MOUNTED | ST_NEW_MOUNT);
  963         periph->periph_flags &= ~PERIPH_MEDIA_LOADED;
  964 }
  965 
  966 /*
  967  * Given all we know about the device, media, mode, 'quirks' and
  968  * initial operation, make a decision as to how we should be set
  969  * to run (regarding blocking and EOD marks)
  970  */
  971 int
  972 st_decide_mode(struct st_softc *st, boolean first_read)
  973 {
  974 
  975         SC_DEBUG(st->sc_periph, SCSIPI_DB2, ("starting block mode decision\n"));
  976 
  977         /*
  978          * If the drive can only handle fixed-length blocks and only at
  979          * one size, perhaps we should just do that.
  980          */
  981         if (st->blkmin && (st->blkmin == st->blkmax)) {
  982                 st->flags |= ST_FIXEDBLOCKS;
  983                 st->blksize = st->blkmin;
  984                 SC_DEBUG(st->sc_periph, SCSIPI_DB3,
  985                     ("blkmin == blkmax of %d\n", st->blkmin));
  986                 goto done;
  987         }
  988         /*
  989          * If the tape density mandates (or even suggests) use of fixed
  990          * or variable-length blocks, comply.
  991          */
  992         switch (st->density) {
  993         case HALFINCH_800:
  994         case HALFINCH_1600:
  995         case HALFINCH_6250:
  996         case DDS:
  997                 st->flags &= ~ST_FIXEDBLOCKS;
  998                 st->blksize = 0;
  999                 SC_DEBUG(st->sc_periph, SCSIPI_DB3,
 1000                     ("density specified variable\n"));
 1001                 goto done;
 1002         case QIC_11:
 1003         case QIC_24:
 1004         case QIC_120:
 1005         case QIC_150:
 1006         case QIC_525:
 1007         case QIC_1320:
 1008         case QIC_3095:
 1009         case QIC_3220:
 1010                 st->flags |= ST_FIXEDBLOCKS;
 1011                 if (st->media_blksize > 0)
 1012                         st->blksize = st->media_blksize;
 1013                 else
 1014                         st->blksize = DEF_FIXED_BSIZE;
 1015                 SC_DEBUG(st->sc_periph, SCSIPI_DB3,
 1016                     ("density specified fixed\n"));
 1017                 goto done;
 1018         }
 1019         /*
 1020          * If we're about to read the tape, perhaps we should choose
 1021          * fixed or variable-length blocks and block size according to
 1022          * what the drive found on the tape.
 1023          */
 1024         if (first_read &&
 1025             (!(st->quirks & ST_Q_BLKSIZE) || (st->media_blksize == 0) ||
 1026             (st->media_blksize == DEF_FIXED_BSIZE) ||
 1027             (st->media_blksize == 1024))) {
 1028                 if (st->media_blksize > 0)
 1029                         st->flags |= ST_FIXEDBLOCKS;
 1030                 else
 1031                         st->flags &= ~ST_FIXEDBLOCKS;
 1032                 st->blksize = st->media_blksize;
 1033                 SC_DEBUG(st->sc_periph, SCSIPI_DB3,
 1034                     ("Used media_blksize of %d\n", st->media_blksize));
 1035                 goto done;
 1036         }
 1037         /*
 1038          * We're getting no hints from any direction.  Choose variable-
 1039          * length blocks arbitrarily.
 1040          */
 1041         st->flags &= ~ST_FIXEDBLOCKS;
 1042         st->blksize = 0;
 1043         SC_DEBUG(st->sc_periph, SCSIPI_DB3,
 1044             ("Give up and default to variable mode\n"));
 1045 
 1046 done:
 1047         /*
 1048          * Decide whether or not to write two file marks to signify end-
 1049          * of-data.  Make the decision as a function of density.  If
 1050          * the decision is not to use a second file mark, the SCSI BLANK
 1051          * CHECK condition code will be recognized as end-of-data when
 1052          * first read.
 1053          * (I think this should be a by-product of fixed/variable..julian)
 1054          */
 1055         switch (st->density) {
 1056 /*      case 8 mm:   What is the SCSI density code for 8 mm, anyway? */
 1057         case QIC_11:
 1058         case QIC_24:
 1059         case QIC_120:
 1060         case QIC_150:
 1061         case QIC_525:
 1062         case QIC_1320:
 1063         case QIC_3095:
 1064         case QIC_3220:
 1065                 st->flags &= ~ST_2FM_AT_EOD;
 1066                 break;
 1067         default:
 1068                 st->flags |= ST_2FM_AT_EOD;
 1069         }
 1070         return (0);
 1071 }
 1072 
 1073 /*
 1074  * Actually translate the requested transfer into
 1075  * one the physical driver can understand
 1076  * The transfer is described by a buf and will include
 1077  * only one physical transfer.
 1078  */
 1079 static void
 1080 ststrategy(struct buf *bp)
 1081 {
 1082         struct st_softc *st = st_cd.cd_devs[STUNIT(bp->b_dev)];
 1083         int s;
 1084 
 1085         SC_DEBUG(st->sc_periph, SCSIPI_DB1,
 1086             ("ststrategy %d bytes @ blk %" PRId64 "\n", bp->b_bcount, bp->b_blkno));
 1087         /*
 1088          * If it's a null transfer, return immediatly
 1089          */
 1090         if (bp->b_bcount == 0)
 1091                 goto done;
 1092 
 1093         /* If offset is negative, error */
 1094         if (bp->b_blkno < 0) {
 1095                 bp->b_error = EINVAL;
 1096                 goto bad;
 1097         }
 1098 
 1099         /*
 1100          * Odd sized request on fixed drives are verboten
 1101          */
 1102         if (st->flags & ST_FIXEDBLOCKS) {
 1103                 if (bp->b_bcount % st->blksize) {
 1104                         printf("%s: bad request, must be multiple of %d\n",
 1105                             st->sc_dev.dv_xname, st->blksize);
 1106                         bp->b_error = EIO;
 1107                         goto bad;
 1108                 }
 1109         }
 1110         /*
 1111          * as are out-of-range requests on variable drives.
 1112          */
 1113         else if (bp->b_bcount < st->blkmin ||
 1114             (st->blkmax && bp->b_bcount > st->blkmax)) {
 1115                 printf("%s: bad request, must be between %d and %d\n",
 1116                     st->sc_dev.dv_xname, st->blkmin, st->blkmax);
 1117                 bp->b_error = EIO;
 1118                 goto bad;
 1119         }
 1120         s = splbio();
 1121 
 1122         /*
 1123          * Place it in the queue of activities for this tape
 1124          * at the end (a bit silly because we only have on user..
 1125          * (but it could fork()))
 1126          */
 1127         BUFQ_PUT(st->buf_queue, bp);
 1128 
 1129         /*
 1130          * Tell the device to get going on the transfer if it's
 1131          * not doing anything, otherwise just wait for completion
 1132          * (All a bit silly if we're only allowing 1 open but..)
 1133          */
 1134         ststart(st->sc_periph);
 1135 
 1136         splx(s);
 1137         return;
 1138 bad:
 1139         bp->b_flags |= B_ERROR;
 1140 done:
 1141         /*
 1142          * Correctly set the buf to indicate a completed xfer
 1143          */
 1144         bp->b_resid = bp->b_bcount;
 1145         biodone(bp);
 1146         return;
 1147 }
 1148 
 1149 /*
 1150  * ststart looks to see if there is a buf waiting for the device
 1151  * and that the device is not already busy. If both are true,
 1152  * It dequeues the buf and creates a scsi command to perform the
 1153  * transfer required. The transfer request will call scsipi_done
 1154  * on completion, which will in turn call this routine again
 1155  * so that the next queued transfer is performed.
 1156  * The bufs are queued by the strategy routine (ststrategy)
 1157  *
 1158  * This routine is also called after other non-queued requests
 1159  * have been made of the scsi driver, to ensure that the queue
 1160  * continues to be drained.
 1161  * ststart() is called at splbio
 1162  */
 1163 static void
 1164 ststart(struct scsipi_periph *periph)
 1165 {
 1166         struct st_softc *st = (void *)periph->periph_dev;
 1167         struct buf *bp;
 1168         struct scsi_rw_tape cmd;
 1169         struct scsipi_xfer *xs;
 1170         int flags, error;
 1171 
 1172         SC_DEBUG(periph, SCSIPI_DB2, ("ststart "));
 1173         /*
 1174          * See if there is a buf to do and we are not already
 1175          * doing one
 1176          */
 1177         while (periph->periph_active < periph->periph_openings) {
 1178                 /* if a special awaits, let it proceed first */
 1179                 if (periph->periph_flags & PERIPH_WAITING) {
 1180                         periph->periph_flags &= ~PERIPH_WAITING;
 1181                         wakeup((caddr_t)periph);
 1182                         return;
 1183                 }
 1184 
 1185                 /*
 1186                  * If the device has been unmounted by the user
 1187                  * then throw away all requests until done.
 1188                  */
 1189                 if (__predict_false((st->flags & ST_MOUNTED) == 0 ||
 1190                     (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0)) {
 1191                         if ((bp = BUFQ_GET(st->buf_queue)) != NULL) {
 1192                                 /* make sure that one implies the other.. */
 1193                                 periph->periph_flags &= ~PERIPH_MEDIA_LOADED;
 1194                                 bp->b_flags |= B_ERROR;
 1195                                 bp->b_error = EIO;
 1196                                 bp->b_resid = bp->b_bcount;
 1197                                 biodone(bp);
 1198                                 continue;
 1199                         } else {
 1200                                 return;
 1201                         }
 1202                 }
 1203 
 1204                 if ((bp = BUFQ_PEEK(st->buf_queue)) == NULL)
 1205                         return;
 1206 
 1207                 iostat_busy(st->stats);
 1208 
 1209                 /*
 1210                  * only FIXEDBLOCK devices have pending I/O or space operations.
 1211                  */
 1212                 if (st->flags & ST_FIXEDBLOCKS) {
 1213                         /*
 1214                          * If we are at a filemark but have not reported it yet
 1215                          * then we should report it now
 1216                          */
 1217                         if (st->flags & ST_AT_FILEMARK) {
 1218                                 if ((bp->b_flags & B_READ) == B_WRITE) {
 1219                                         /*
 1220                                          * Handling of ST_AT_FILEMARK in
 1221                                          * st_space will fill in the right file
 1222                                          * mark count.
 1223                                          * Back up over filemark
 1224                                          */
 1225                                         if (st_space(st, 0, SP_FILEMARKS, 0)) {
 1226                                                 BUFQ_GET(st->buf_queue);
 1227                                                 bp->b_flags |= B_ERROR;
 1228                                                 bp->b_error = EIO;
 1229                                                 bp->b_resid = bp->b_bcount;
 1230                                                 biodone(bp);
 1231                                                 continue;
 1232                                         }
 1233                                 } else {
 1234                                         BUFQ_GET(st->buf_queue);
 1235                                         bp->b_resid = bp->b_bcount;
 1236                                         bp->b_error = 0;
 1237                                         bp->b_flags &= ~B_ERROR;
 1238                                         st->flags &= ~ST_AT_FILEMARK;
 1239                                         biodone(bp);
 1240                                         continue;       /* seek more work */
 1241                                 }
 1242                         }
 1243                 }
 1244                 /*
 1245                  * If we are at EOM but have not reported it
 1246                  * yet then we should report it now.
 1247                  */
 1248                 if (st->flags & (ST_EOM_PENDING|ST_EIO_PENDING)) {
 1249                         BUFQ_GET(st->buf_queue);
 1250                         bp->b_resid = bp->b_bcount;
 1251                         if (st->flags & ST_EIO_PENDING) {
 1252                                 bp->b_error = EIO;
 1253                                 bp->b_flags |= B_ERROR;
 1254                         }
 1255                         st->flags &= ~(ST_EOM_PENDING|ST_EIO_PENDING);
 1256                         biodone(bp);
 1257                         continue;       /* seek more work */
 1258                 }
 1259 
 1260                 /*
 1261                  * Fill out the scsi command
 1262                  */
 1263                 memset(&cmd, 0, sizeof(cmd));
 1264                 flags = XS_CTL_NOSLEEP | XS_CTL_ASYNC;
 1265                 if ((bp->b_flags & B_READ) == B_WRITE) {
 1266                         cmd.opcode = WRITE;
 1267                         st->flags &= ~ST_FM_WRITTEN;
 1268                         flags |= XS_CTL_DATA_OUT;
 1269                 } else {
 1270                         cmd.opcode = READ;
 1271                         flags |= XS_CTL_DATA_IN;
 1272                 }
 1273 
 1274                 /*
 1275                  * Handle "fixed-block-mode" tape drives by using the
 1276                  * block count instead of the length.
 1277                  */
 1278                 if (st->flags & ST_FIXEDBLOCKS) {
 1279                         cmd.byte2 |= SRW_FIXED;
 1280                         _lto3b(bp->b_bcount / st->blksize, cmd.len);
 1281                 } else
 1282                         _lto3b(bp->b_bcount, cmd.len);
 1283 
 1284                 /*
 1285                  * Clear 'position updated' indicator
 1286                  */
 1287                 st->flags &= ~ST_POSUPDATED;
 1288 
 1289                 /*
 1290                  * go ask the adapter to do all this for us
 1291                  */
 1292                 xs = scsipi_make_xs(periph,
 1293                     (struct scsipi_generic *)&cmd, sizeof(cmd),
 1294                     (u_char *)bp->b_data, bp->b_bcount,
 1295                     0, ST_IO_TIME, bp, flags);
 1296                 if (__predict_false(xs == NULL)) {
 1297                         /*
 1298                          * out of memory. Keep this buffer in the queue, and
 1299                          * retry later.
 1300                          */
 1301                         callout_reset(&st->sc_callout, hz / 2, strestart,
 1302                             periph);
 1303                         return;
 1304                 }
 1305                 /*
 1306                  * need to dequeue the buffer before queuing the command,
 1307                  * because cdstart may be called recursively from the
 1308                  * HBA driver
 1309                  */
 1310 #ifdef DIAGNOSTIC
 1311                 if (BUFQ_GET(st->buf_queue) != bp)
 1312                         panic("ststart(): dequeued wrong buf");
 1313 #else
 1314                 BUFQ_GET(st->buf_queue);
 1315 #endif
 1316                 error = scsipi_execute_xs(xs);
 1317                 /* with a scsipi_xfer preallocated, scsipi_command can't fail */
 1318                 KASSERT(error == 0);
 1319         } /* go back and see if we can cram more work in.. */
 1320 }
 1321 
 1322 static void
 1323 strestart(void *v)
 1324 {
 1325         int s = splbio();
 1326         ststart((struct scsipi_periph *)v);
 1327         splx(s);
 1328 }
 1329 
 1330 
 1331 static void
 1332 stdone(struct scsipi_xfer *xs, int error)
 1333 {
 1334         struct st_softc *st = (void *)xs->xs_periph->periph_dev;
 1335         struct buf *bp = xs->bp;
 1336 
 1337         if (bp) {
 1338                 bp->b_error = error;
 1339                 bp->b_resid = xs->resid;
 1340                 if (error)
 1341                         bp->b_flags |= B_ERROR;
 1342                 /*
 1343                  * buggy device ? A SDLT320 can report an info
 1344                  * field of 0x3de8000 on a Media Error/Write Error
 1345                  * for this CBD: 0x0a 00 00 80 00 00
 1346                  */
 1347                 if (bp->b_resid > bp->b_bcount || bp->b_resid < 0)
 1348                         bp->b_resid = bp->b_bcount;
 1349 
 1350                 if ((bp->b_flags & B_READ) == B_WRITE)
 1351                         st->flags |= ST_WRITTEN;
 1352                 else
 1353                         st->flags &= ~ST_WRITTEN;
 1354 
 1355                 iostat_unbusy(st->stats, bp->b_bcount,
 1356                              ((bp->b_flags & B_READ) == B_READ));
 1357 
 1358 #if NRND > 0
 1359                 rnd_add_uint32(&st->rnd_source, bp->b_blkno);
 1360 #endif
 1361 
 1362                 if ((st->flags & ST_POSUPDATED) == 0) {
 1363                         if (error) {
 1364                                 st->fileno = st->blkno = -1;
 1365                         } else if (st->blkno != -1) {
 1366                                 if (st->flags & ST_FIXEDBLOCKS)
 1367                                         st->blkno +=
 1368                                             (bp->b_bcount / st->blksize);
 1369                                 else
 1370                                         st->blkno++;
 1371                         }
 1372                 }
 1373 
 1374                 biodone(bp);
 1375         }
 1376 }
 1377 
 1378 static int
 1379 stread(dev_t dev, struct uio *uio, int iomode)
 1380 {
 1381         struct st_softc *st = st_cd.cd_devs[STUNIT(dev)];
 1382 
 1383         return (physio(ststrategy, NULL, dev, B_READ,
 1384             st->sc_periph->periph_channel->chan_adapter->adapt_minphys, uio));
 1385 }
 1386 
 1387 static int
 1388 stwrite(dev_t dev, struct uio *uio, int iomode)
 1389 {
 1390         struct st_softc *st = st_cd.cd_devs[STUNIT(dev)];
 1391 
 1392         return (physio(ststrategy, NULL, dev, B_WRITE,
 1393             st->sc_periph->periph_channel->chan_adapter->adapt_minphys, uio));
 1394 }
 1395 
 1396 /*
 1397  * Perform special action on behalf of the user;
 1398  * knows about the internals of this device
 1399  */
 1400 static int
 1401 stioctl(dev_t dev, u_long cmd, caddr_t arg, int flag, struct lwp *l)
 1402 {
 1403         int error = 0;
 1404         int unit;
 1405         int number, nmarks, dsty;
 1406         int flags;
 1407         struct st_softc *st;
 1408         int hold_blksize;
 1409         u_int8_t hold_density;
 1410         struct mtop *mt = (struct mtop *) arg;
 1411 
 1412         /*
 1413          * Find the device that the user is talking about
 1414          */
 1415         flags = 0;              /* give error messages, act on errors etc. */
 1416         unit = STUNIT(dev);
 1417         dsty = STDSTY(dev);
 1418         st = st_cd.cd_devs[unit];
 1419         hold_blksize = st->blksize;
 1420         hold_density = st->density;
 1421 
 1422         switch ((u_int) cmd) {
 1423 
 1424         case MTIOCGET: {
 1425                 struct mtget *g = (struct mtget *) arg;
 1426                 /*
 1427                  * (to get the current state of READONLY)
 1428                  */
 1429                 error = st->ops(st, ST_OPS_MODESENSE, XS_CTL_SILENT);
 1430                 if (error) {
 1431                         /*
 1432                          * Ignore the error if in control mode;
 1433                          * this is mandated by st(4).
 1434                          */
 1435                         if (STMODE(dev) != CTRL_MODE)
 1436                                 break;
 1437                         error = 0;
 1438                 }
 1439                 SC_DEBUG(st->sc_periph, SCSIPI_DB1, ("[ioctl: get status]\n"));
 1440                 memset(g, 0, sizeof(struct mtget));
 1441                 g->mt_type = 0x7;       /* Ultrix compat *//*? */
 1442                 g->mt_blksiz = st->blksize;
 1443                 g->mt_density = st->density;
 1444                 g->mt_mblksiz[0] = st->modes[0].blksize;
 1445                 g->mt_mblksiz[1] = st->modes[1].blksize;
 1446                 g->mt_mblksiz[2] = st->modes[2].blksize;
 1447                 g->mt_mblksiz[3] = st->modes[3].blksize;
 1448                 g->mt_mdensity[0] = st->modes[0].density;
 1449                 g->mt_mdensity[1] = st->modes[1].density;
 1450                 g->mt_mdensity[2] = st->modes[2].density;
 1451                 g->mt_mdensity[3] = st->modes[3].density;
 1452                 g->mt_fileno = st->fileno;
 1453                 g->mt_blkno = st->blkno;
 1454                 if (st->flags & ST_READONLY)
 1455                         g->mt_dsreg |= MT_DS_RDONLY;
 1456                 if (st->flags & ST_MOUNTED)
 1457                         g->mt_dsreg |= MT_DS_MOUNTED;
 1458                 g->mt_resid = st->mt_resid;
 1459                 g->mt_erreg = st->mt_erreg;
 1460                 /*
 1461                  * clear latched errors.
 1462                  */
 1463                 st->mt_resid = 0;
 1464                 st->mt_erreg = 0;
 1465                 st->asc = 0;
 1466                 st->ascq = 0;
 1467                 break;
 1468         }
 1469         case MTIOCTOP: {
 1470 
 1471                 SC_DEBUG(st->sc_periph, SCSIPI_DB1,
 1472                     ("[ioctl: op=0x%x count=0x%x]\n", mt->mt_op,
 1473                         mt->mt_count));
 1474 
 1475                 /* compat: in U*x it is a short */
 1476                 number = mt->mt_count;
 1477                 switch ((short) (mt->mt_op)) {
 1478                 case MTWEOF:    /* write an end-of-file record */
 1479                         error = st_write_filemarks(st, number, flags);
 1480                         break;
 1481                 case MTBSF:     /* backward space file */
 1482                         number = -number;
 1483                 case MTFSF:     /* forward space file */
 1484                         error = st_check_eod(st, FALSE, &nmarks, flags);
 1485                         if (!error)
 1486                                 error = st_space(st, number - nmarks,
 1487                                     SP_FILEMARKS, flags);
 1488                         break;
 1489                 case MTBSR:     /* backward space record */
 1490                         number = -number;
 1491                 case MTFSR:     /* forward space record */
 1492                         error = st_check_eod(st, TRUE, &nmarks, flags);
 1493                         if (!error)
 1494                                 error = st_space(st, number, SP_BLKS, flags);
 1495                         break;
 1496                 case MTREW:     /* rewind */
 1497                         error = st_rewind(st, 0, flags);
 1498                         break;
 1499                 case MTOFFL:    /* rewind and put the drive offline */
 1500                         st_unmount(st, EJECT);
 1501                         break;
 1502                 case MTNOP:     /* no operation, sets status only */
 1503                         break;
 1504                 case MTRETEN:   /* retension the tape */
 1505                         error = st_load(st, LD_RETENSION, flags);
 1506                         if (!error)
 1507                                 error = st_load(st, LD_LOAD, flags);
 1508                         break;
 1509                 case MTEOM:     /* forward space to end of media */
 1510                         error = st_check_eod(st, FALSE, &nmarks, flags);
 1511                         if (!error)
 1512                                 error = st_space(st, 1, SP_EOM, flags);
 1513                         break;
 1514                 case MTCACHE:   /* enable controller cache */
 1515                         st->flags &= ~ST_DONTBUFFER;
 1516                         goto try_new_value;
 1517                 case MTNOCACHE: /* disable controller cache */
 1518                         st->flags |= ST_DONTBUFFER;
 1519                         goto try_new_value;
 1520                 case MTERASE:   /* erase volume */
 1521                         error = st_erase(st, number, flags);
 1522                         break;
 1523                 case MTSETBSIZ: /* Set block size for device */
 1524 #ifdef  NOTYET
 1525                         if (!(st->flags & ST_NEW_MOUNT)) {
 1526                                 uprintf("re-mount tape before changing blocksize");
 1527                                 error = EINVAL;
 1528                                 break;
 1529                         }
 1530 #endif
 1531                         if (number == 0)
 1532                                 st->flags &= ~ST_FIXEDBLOCKS;
 1533                         else {
 1534                                 if ((st->blkmin || st->blkmax) &&
 1535                                     (number < st->blkmin ||
 1536                                     number > st->blkmax)) {
 1537                                         error = EINVAL;
 1538                                         break;
 1539                                 }
 1540                                 st->flags |= ST_FIXEDBLOCKS;
 1541                         }
 1542                         st->blksize = number;
 1543                         st->flags |= ST_BLOCK_SET;      /*XXX */
 1544                         goto try_new_value;
 1545 
 1546                 case MTSETDNSTY:        /* Set density for device and mode */
 1547                         /*
 1548                          * Any number >= 0 and <= 0xff is legal. Numbers
 1549                          * above 0x80 are 'vendor unique'.
 1550                          */
 1551                         if (number < 0 || number > 255) {
 1552                                 error = EINVAL;
 1553                                 break;
 1554                         } else
 1555                                 st->density = number;
 1556                         goto try_new_value;
 1557 
 1558                 case MTCMPRESS:
 1559                         error = st->ops(st, (number == 0) ?
 1560                             ST_OPS_CMPRSS_OFF : ST_OPS_CMPRSS_ON,
 1561                             XS_CTL_SILENT);
 1562                         break;
 1563 
 1564                 case MTEWARN:
 1565                         if (number)
 1566                                 st->flags |= ST_EARLYWARN;
 1567                         else
 1568                                 st->flags &= ~ST_EARLYWARN;
 1569                         break;
 1570 
 1571                 default:
 1572                         error = EINVAL;
 1573                 }
 1574                 break;
 1575         }
 1576         case MTIOCIEOT:
 1577         case MTIOCEEOT:
 1578                 break;
 1579 
 1580         case MTIOCRDSPOS:
 1581                 error = st_rdpos(st, 0, (u_int32_t *) arg);
 1582                 break;
 1583 
 1584         case MTIOCRDHPOS:
 1585                 error = st_rdpos(st, 1, (u_int32_t *) arg);
 1586                 break;
 1587 
 1588         case MTIOCSLOCATE:
 1589                 error = st_setpos(st, 0, (u_int32_t *) arg);
 1590                 break;
 1591 
 1592         case MTIOCHLOCATE:
 1593                 error = st_setpos(st, 1, (u_int32_t *) arg);
 1594                 break;
 1595 
 1596 
 1597         default:
 1598                 error = scsipi_do_ioctl(st->sc_periph, dev, cmd, arg,
 1599                                         flag, l);
 1600                 break;
 1601         }
 1602         return (error);
 1603 /*-----------------------------*/
 1604 try_new_value:
 1605         /*
 1606          * Check that the mode being asked for is aggreeable to the
 1607          * drive. If not, put it back the way it was.
 1608          *
 1609          * If in control mode, we can make (persistent) mode changes
 1610          * even if no medium is loaded (see st(4)).
 1611          */
 1612         if ((STMODE(dev) != CTRL_MODE || (st->flags & ST_MOUNTED) != 0) &&
 1613             (error = st->ops(st, ST_OPS_MODESELECT, 0)) != 0) {
 1614                 /* put it back as it was */
 1615                 printf("%s: cannot set selected mode\n", st->sc_dev.dv_xname);
 1616                 st->density = hold_density;
 1617                 st->blksize = hold_blksize;
 1618                 if (st->blksize)
 1619                         st->flags |= ST_FIXEDBLOCKS;
 1620                 else
 1621                         st->flags &= ~ST_FIXEDBLOCKS;
 1622                 return (error);
 1623         }
 1624         /*
 1625          * As the drive liked it, if we are setting a new default,
 1626          * set it into the structures as such.
 1627          *
 1628          * The means for deciding this are not finalised yet- but
 1629          * if the device was opened in Control Mode, the values
 1630          * are persistent now across mounts.
 1631          */
 1632         if (STMODE(dev) == CTRL_MODE) {
 1633                 switch ((short) (mt->mt_op)) {
 1634                 case MTSETBSIZ:
 1635                         st->modes[dsty].blksize = st->blksize;
 1636                         st->modeflags[dsty] |= BLKSIZE_SET_BY_USER;
 1637                         break;
 1638                 case MTSETDNSTY:
 1639                         st->modes[dsty].density = st->density;
 1640                         st->modeflags[dsty] |= DENSITY_SET_BY_USER;
 1641                         break;
 1642                 }
 1643         }
 1644         return (0);
 1645 }
 1646 
 1647 /*
 1648  * Do a synchronous read.
 1649  */
 1650 static int
 1651 st_read(struct st_softc *st, char *bf, int size, int flags)
 1652 {
 1653         struct scsi_rw_tape cmd;
 1654 
 1655         /*
 1656          * If it's a null transfer, return immediatly
 1657          */
 1658         if (size == 0)
 1659                 return (0);
 1660         memset(&cmd, 0, sizeof(cmd));
 1661         cmd.opcode = READ;
 1662         if (st->flags & ST_FIXEDBLOCKS) {
 1663                 cmd.byte2 |= SRW_FIXED;
 1664                 _lto3b(size / (st->blksize ? st->blksize : DEF_FIXED_BSIZE),
 1665                     cmd.len);
 1666         } else
 1667                 _lto3b(size, cmd.len);
 1668         return (scsipi_command(st->sc_periph,
 1669             (void *)&cmd, sizeof(cmd), (void *)bf, size, 0, ST_IO_TIME, NULL,
 1670             flags | XS_CTL_DATA_IN));
 1671 }
 1672 
 1673 /*
 1674  * issue an erase command
 1675  */
 1676 static int
 1677 st_erase(struct st_softc *st, int full, int flags)
 1678 {
 1679         int tmo;
 1680         struct scsi_erase cmd;
 1681 
 1682         /*
 1683          * Full erase means set LONG bit in erase command, which asks
 1684          * the drive to erase the entire unit.  Without this bit, we're
 1685          * asking the drive to write an erase gap.
 1686          */
 1687         memset(&cmd, 0, sizeof(cmd));
 1688         cmd.opcode = ERASE;
 1689         if (full) {
 1690                 cmd.byte2 = SE_LONG;
 1691                 tmo = ST_SPC_TIME;
 1692         } else {
 1693                 tmo = ST_IO_TIME;
 1694         }
 1695 
 1696         /*
 1697          * XXX We always do this asynchronously, for now, unless the device
 1698          * has the ST_Q_ERASE_NOIMM quirk.  How long should we wait if we
 1699          * want to (eventually) to it synchronously?
 1700          */
 1701         if ((st->quirks & ST_Q_ERASE_NOIMM) == 0)
 1702                 cmd.byte2 |= SE_IMMED;
 1703 
 1704         return (scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
 1705             ST_RETRIES, tmo, NULL, flags));
 1706 }
 1707 
 1708 /*
 1709  * skip N blocks/filemarks/seq filemarks/eom
 1710  */
 1711 static int
 1712 st_space(struct st_softc *st, int number, u_int what, int flags)
 1713 {
 1714         struct scsi_space cmd;
 1715         int error;
 1716 
 1717         switch (what) {
 1718         case SP_BLKS:
 1719                 if (st->flags & ST_PER_ACTION) {
 1720                         if (number > 0) {
 1721                                 st->flags &= ~ST_PER_ACTION;
 1722                                 return (EIO);
 1723                         } else if (number < 0) {
 1724                                 if (st->flags & ST_AT_FILEMARK) {
 1725                                         /*
 1726                                          * Handling of ST_AT_FILEMARK
 1727                                          * in st_space will fill in the
 1728                                          * right file mark count.
 1729                                          */
 1730                                         error = st_space(st, 0, SP_FILEMARKS,
 1731                                             flags);
 1732                                         if (error)
 1733                                                 return (error);
 1734                                 }
 1735                                 if (st->flags & ST_BLANK_READ) {
 1736                                         st->flags &= ~ST_BLANK_READ;
 1737                                         return (EIO);
 1738                                 }
 1739                                 st->flags &= ~(ST_EIO_PENDING|ST_EOM_PENDING);
 1740                         }
 1741                 }
 1742                 break;
 1743         case SP_FILEMARKS:
 1744                 if (st->flags & ST_EIO_PENDING) {
 1745                         if (number > 0) {
 1746                                 /* pretend we just discovered the error */
 1747                                 st->flags &= ~ST_EIO_PENDING;
 1748                                 return (EIO);
 1749                         } else if (number < 0) {
 1750                                 /* back away from the error */
 1751                                 st->flags &= ~ST_EIO_PENDING;
 1752                         }
 1753                 }
 1754                 if (st->flags & ST_AT_FILEMARK) {
 1755                         st->flags &= ~ST_AT_FILEMARK;
 1756                         number--;
 1757                 }
 1758                 if ((st->flags & ST_BLANK_READ) && (number < 0)) {
 1759                         /* back away from unwritten tape */
 1760                         st->flags &= ~ST_BLANK_READ;
 1761                         number++;       /* XXX dubious */
 1762                 }
 1763                 break;
 1764         case SP_EOM:
 1765                 if (st->flags & ST_EOM_PENDING) {
 1766                         /* we're already there */
 1767                         st->flags &= ~ST_EOM_PENDING;
 1768                         return (0);
 1769                 }
 1770                 if (st->flags & ST_EIO_PENDING) {
 1771                         /* pretend we just discovered the error */
 1772                         st->flags &= ~ST_EIO_PENDING;
 1773                         return (EIO);
 1774                 }
 1775                 if (st->flags & ST_AT_FILEMARK)
 1776                         st->flags &= ~ST_AT_FILEMARK;
 1777                 break;
 1778         }
 1779         if (number == 0)
 1780                 return (0);
 1781 
 1782         memset(&cmd, 0, sizeof(cmd));
 1783         cmd.opcode = SPACE;
 1784         cmd.byte2 = what;
 1785         _lto3b(number, cmd.number);
 1786 
 1787         st->flags &= ~ST_POSUPDATED;
 1788         st->last_ctl_resid = 0;
 1789         error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
 1790             0, ST_SPC_TIME, NULL, flags);
 1791 
 1792         if (error == 0 && (st->flags & ST_POSUPDATED) == 0) {
 1793                 number = number - st->last_ctl_resid;
 1794                 if (what == SP_BLKS) {
 1795                         if (st->blkno != -1) {
 1796                                 st->blkno += number;
 1797                         }
 1798                 } else if (what == SP_FILEMARKS) {
 1799                         if (st->fileno != -1) {
 1800                                 st->fileno += number;
 1801                                 if (number > 0) {
 1802                                         st->blkno = 0;
 1803                                 } else if (number < 0) {
 1804                                         st->blkno = -1;
 1805                                 }
 1806                         }
 1807                 } else if (what == SP_EOM) {
 1808                         /*
 1809                          * This loses us relative position.
 1810                          */
 1811                         st->fileno = st->blkno = -1;
 1812                 }
 1813         }
 1814         return (error);
 1815 }
 1816 
 1817 /*
 1818  * write N filemarks
 1819  */
 1820 static int
 1821 st_write_filemarks(struct st_softc *st, int number, int flags)
 1822 {
 1823         int error;
 1824         struct scsi_write_filemarks cmd;
 1825 
 1826         /*
 1827          * It's hard to write a negative number of file marks.
 1828          * Don't try.
 1829          */
 1830         if (number < 0)
 1831                 return (EINVAL);
 1832         switch (number) {
 1833         case 0:         /* really a command to sync the drive's buffers */
 1834                 break;
 1835         case 1:
 1836                 if (st->flags & ST_FM_WRITTEN)  /* already have one down */
 1837                         st->flags &= ~ST_WRITTEN;
 1838                 else
 1839                         st->flags |= ST_FM_WRITTEN;
 1840                 st->flags &= ~ST_PER_ACTION;
 1841                 break;
 1842         default:
 1843                 st->flags &= ~(ST_PER_ACTION | ST_WRITTEN);
 1844         }
 1845 
 1846         memset(&cmd, 0, sizeof(cmd));
 1847         cmd.opcode = WRITE_FILEMARKS;
 1848         if (scsipi_periph_bustype(st->sc_periph) == SCSIPI_BUSTYPE_ATAPI)
 1849                 cmd.byte2 = SR_IMMED;
 1850         /*
 1851          * The ATAPI Onstream DI-30 doesn't support writing filemarks, but
 1852          * WRITE_FILEMARKS is still used to flush the buffer
 1853          */
 1854         if ((st->quirks & ST_Q_NOFILEMARKS) == 0)
 1855                 _lto3b(number, cmd.number);
 1856 
 1857         /* XXX WE NEED TO BE ABLE TO GET A RESIDIUAL XXX */
 1858         error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
 1859             0, ST_IO_TIME * 4, NULL, flags);
 1860         if (error == 0 && st->fileno != -1) {
 1861                 st->fileno += number;
 1862         }
 1863         return (error);
 1864 }
 1865 
 1866 /*
 1867  * Make sure the right number of file marks is on tape if the
 1868  * tape has been written.  If the position argument is true,
 1869  * leave the tape positioned where it was originally.
 1870  *
 1871  * nmarks returns the number of marks to skip (or, if position
 1872  * true, which were skipped) to get back original position.
 1873  */
 1874 static int
 1875 st_check_eod(struct st_softc *st, boolean position, int *nmarks, int flags)
 1876 {
 1877         int error;
 1878 
 1879         switch (st->flags & (ST_WRITTEN | ST_FM_WRITTEN | ST_2FM_AT_EOD)) {
 1880         default:
 1881                 *nmarks = 0;
 1882                 return (0);
 1883         case ST_WRITTEN:
 1884         case ST_WRITTEN | ST_FM_WRITTEN | ST_2FM_AT_EOD:
 1885                 *nmarks = 1;
 1886                 break;
 1887         case ST_WRITTEN | ST_2FM_AT_EOD:
 1888                 *nmarks = 2;
 1889         }
 1890         error = st_write_filemarks(st, *nmarks, flags);
 1891         if (position && !error)
 1892                 error = st_space(st, -*nmarks, SP_FILEMARKS, flags);
 1893         return (error);
 1894 }
 1895 
 1896 /*
 1897  * load/unload/retension
 1898  */
 1899 static int
 1900 st_load(struct st_softc *st, u_int type, int flags)
 1901 {
 1902         int error;
 1903         struct scsi_load cmd;
 1904 
 1905         if (type != LD_LOAD) {
 1906                 int nmarks;
 1907 
 1908                 error = st_check_eod(st, FALSE, &nmarks, flags);
 1909                 if (error) {
 1910                         printf("%s: failed to write closing filemarks at "
 1911                             "unload, errno=%d\n", st->sc_dev.dv_xname, error);
 1912                         return (error);
 1913                 }
 1914         }
 1915         if (st->quirks & ST_Q_IGNORE_LOADS) {
 1916                 if (type == LD_LOAD) {
 1917                         /*
 1918                          * If we ignore loads, at least we should try a rewind.
 1919                          */
 1920                         return st_rewind(st, 0, flags);
 1921                 }
 1922                 /* otherwise, we should do what's asked of us */
 1923         }
 1924 
 1925         memset(&cmd, 0, sizeof(cmd));
 1926         cmd.opcode = LOAD;
 1927         if (scsipi_periph_bustype(st->sc_periph) == SCSIPI_BUSTYPE_ATAPI)
 1928                 cmd.byte2 = SR_IMMED;
 1929         cmd.how = type;
 1930 
 1931         error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
 1932             ST_RETRIES, ST_SPC_TIME, NULL, flags);
 1933         if (error) {
 1934                 printf("%s: error %d in st_load (op %d)\n",
 1935                     st->sc_dev.dv_xname, error, type);
 1936         }
 1937         return (error);
 1938 }
 1939 
 1940 /*
 1941  *  Rewind the device
 1942  */
 1943 static int
 1944 st_rewind(struct st_softc *st, u_int immediate, int flags)
 1945 {
 1946         struct scsi_rewind cmd;
 1947         int error;
 1948         int nmarks;
 1949 
 1950         error = st_check_eod(st, FALSE, &nmarks, flags);
 1951         if (error) {
 1952                 printf("%s: failed to write closing filemarks at "
 1953                     "rewind, errno=%d\n", st->sc_dev.dv_xname, error);
 1954                 return (error);
 1955         }
 1956         st->flags &= ~ST_PER_ACTION;
 1957 
 1958         /*
 1959          * ATAPI tapes always need immediate to be set
 1960          */
 1961         if (scsipi_periph_bustype(st->sc_periph) == SCSIPI_BUSTYPE_ATAPI)
 1962                 immediate = SR_IMMED;
 1963 
 1964         memset(&cmd, 0, sizeof(cmd));
 1965         cmd.opcode = REWIND;
 1966         cmd.byte2 = immediate;
 1967 
 1968         error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
 1969             ST_RETRIES, immediate ? ST_CTL_TIME: ST_SPC_TIME, NULL, flags);
 1970         if (error) {
 1971                 printf("%s: error %d trying to rewind\n",
 1972                     st->sc_dev.dv_xname, error);
 1973                 /* lost position */
 1974                 st->fileno = st->blkno = -1;
 1975         } else {
 1976                 st->fileno = st->blkno = 0;
 1977         }
 1978         return (error);
 1979 }
 1980 
 1981 static int
 1982 st_rdpos(struct st_softc *st, int hard, u_int32_t *blkptr)
 1983 {
 1984         int error;
 1985         u_int8_t posdata[20];
 1986         struct scsi_tape_read_position cmd;
 1987 
 1988         /*
 1989          * We try and flush any buffered writes here if we were writing
 1990          * and we're trying to get hardware block position. It eats
 1991          * up performance substantially, but I'm wary of drive firmware.
 1992          *
 1993          * I think that *logical* block position is probably okay-
 1994          * but hardware block position might have to wait for data
 1995          * to hit media to be valid. Caveat Emptor.
 1996          */
 1997 
 1998         if (hard && (st->flags & ST_WRITTEN)) {
 1999                 /*
 2000                  * First flush any pending writes...
 2001                  */
 2002                 error = st_write_filemarks(st, 0, XS_CTL_SILENT);
 2003                 /*
 2004                  * The latter case is for 'write protected' tapes
 2005                  * which are too stupid to recognize a zero count
 2006                  * for writing filemarks as a no-op.
 2007                  */
 2008                 if (error != 0 && error != EACCES && error != EROFS)
 2009                         return (error);
 2010         }
 2011 
 2012         memset(&cmd, 0, sizeof(cmd));
 2013         memset(&posdata, 0, sizeof(posdata));
 2014         cmd.opcode = READ_POSITION;
 2015         if (hard)
 2016                 cmd.byte1 = 1;
 2017 
 2018         error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd),
 2019             (void *)&posdata, sizeof(posdata), ST_RETRIES, ST_CTL_TIME, NULL,
 2020             XS_CTL_SILENT | XS_CTL_DATA_IN | XS_CTL_DATA_ONSTACK);
 2021 
 2022         if (error == 0) {
 2023 #if     0
 2024                 printf("posdata:");
 2025                 for (hard = 0; hard < sizeof(posdata); hard++)
 2026                         printf("%02x ", posdata[hard] & 0xff);
 2027                 printf("\n");
 2028 #endif
 2029                 if (posdata[0] & 0x4)   /* Block Position Unknown */
 2030                         error = EINVAL;
 2031                 else
 2032                         *blkptr = _4btol(&posdata[4]);
 2033         }
 2034         return (error);
 2035 }
 2036 
 2037 static int
 2038 st_setpos(struct st_softc *st, int hard, u_int32_t *blkptr)
 2039 {
 2040         int error;
 2041         struct scsi_tape_locate cmd;
 2042 
 2043         /*
 2044          * We used to try and flush any buffered writes here.
 2045          * Now we push this onto user applications to either
 2046          * flush the pending writes themselves (via a zero count
 2047          * WRITE FILEMARKS command) or they can trust their tape
 2048          * drive to do this correctly for them.
 2049          *
 2050          * There are very ugly performance limitations otherwise.
 2051          */
 2052 
 2053         memset(&cmd, 0, sizeof(cmd));
 2054         cmd.opcode = LOCATE;
 2055         if (hard)
 2056                 cmd.byte2 = 1 << 2;
 2057         _lto4b(*blkptr, cmd.blkaddr);
 2058         error = scsipi_command(st->sc_periph, (void *)&cmd, sizeof(cmd), 0, 0,
 2059             ST_RETRIES, ST_SPC_TIME, NULL, 0);
 2060         /*
 2061          * Note file && block number position now unknown (if
 2062          * these things ever start being maintained in this driver)
 2063          */
 2064         st->fileno = st->blkno = -1;
 2065         return (error);
 2066 }
 2067 
 2068 
 2069 /*
 2070  * Look at the returned sense and act on the error and determine
 2071  * the unix error number to pass back..., 0 (== report no error),
 2072  * -1 = retry the operation, -2 continue error processing.
 2073  */
 2074 static int
 2075 st_interpret_sense(struct scsipi_xfer *xs)
 2076 {
 2077         struct scsipi_periph *periph = xs->xs_periph;
 2078         struct scsi_sense_data *sense = &xs->sense.scsi_sense;
 2079         struct buf *bp = xs->bp;
 2080         struct st_softc *st = (void *)periph->periph_dev;
 2081         int retval = EJUSTRETURN;
 2082         int doprint = ((xs->xs_control & XS_CTL_SILENT) == 0);
 2083         u_int8_t key;
 2084         int32_t info;
 2085 
 2086         /*
 2087          * If it isn't a extended or extended/deferred error, let
 2088          * the generic code handle it.
 2089          */
 2090         if (SSD_RCODE(sense->response_code) != SSD_RCODE_CURRENT &&
 2091             SSD_RCODE(sense->response_code) != SSD_RCODE_DEFERRED)
 2092                 return (retval);
 2093 
 2094         if (sense->response_code & SSD_RCODE_VALID)
 2095                 info = _4btol(sense->info);
 2096         else
 2097                 info = (st->flags & ST_FIXEDBLOCKS) ?
 2098                     xs->datalen / st->blksize : xs->datalen;
 2099         key = SSD_SENSE_KEY(sense->flags);
 2100         st->mt_erreg = key;
 2101         st->asc = sense->asc;
 2102         st->ascq = sense->ascq;
 2103         st->mt_resid = (short) info;
 2104 
 2105         if (key == SKEY_NOT_READY && st->asc == 0x4 && st->ascq == 0x1) {
 2106                 /* Not Ready, Logical Unit Is in Process Of Becoming Ready */
 2107                 if (!callout_pending(&periph->periph_callout))
 2108                         scsipi_periph_freeze(periph, 1);
 2109                 callout_reset(&periph->periph_callout,
 2110                     hz, scsipi_periph_timed_thaw, periph);
 2111                 return (ERESTART);
 2112         }
 2113 
 2114         /*
 2115          * If the device is not open yet, let generic handle
 2116          */
 2117         if ((periph->periph_flags & PERIPH_OPEN) == 0) {
 2118                 return (retval);
 2119         }
 2120 
 2121         xs->resid = info;
 2122         if (st->flags & ST_FIXEDBLOCKS) {
 2123                 if (bp) {
 2124                         xs->resid *= st->blksize;
 2125                         st->last_io_resid = xs->resid;
 2126                 } else {
 2127                         st->last_ctl_resid = xs->resid;
 2128                 }
 2129                 if (key == SKEY_VOLUME_OVERFLOW) {
 2130                         st->flags |= ST_EIO_PENDING;
 2131                         if (bp)
 2132                                 bp->b_resid = xs->resid;
 2133                 } else if (sense->flags & SSD_EOM) {
 2134                         if ((st->flags & ST_EARLYWARN) == 0)
 2135                                 st->flags |= ST_EIO_PENDING;
 2136                         st->flags |= ST_EOM_PENDING;
 2137                         if (bp) {
 2138 #if 0
 2139                                 bp->b_resid = xs->resid;
 2140 #else
 2141                                 /*
 2142                                  * Grotesque as it seems, the few times
 2143                                  * I've actually seen a non-zero resid,
 2144                                  * the tape drive actually lied and had
 2145                                  * written all the data!
 2146                                  */
 2147                                 bp->b_resid = 0;
 2148 #endif
 2149                         }
 2150                 }
 2151                 if (sense->flags & SSD_FILEMARK) {
 2152                         st->flags |= ST_AT_FILEMARK;
 2153                         if (bp)
 2154                                 bp->b_resid = xs->resid;
 2155                         if (st->fileno != (daddr_t) -1) {
 2156                                 st->fileno++;
 2157                                 st->blkno = 0;
 2158                                 st->flags |= ST_POSUPDATED;
 2159                         }
 2160                 }
 2161                 if (sense->flags & SSD_ILI) {
 2162                         st->flags |= ST_EIO_PENDING;
 2163                         if (bp)
 2164                                 bp->b_resid = xs->resid;
 2165                         if (sense->response_code & SSD_RCODE_VALID &&
 2166                             (xs->xs_control & XS_CTL_SILENT) == 0)
 2167                                 printf("%s: block wrong size, %d blocks "
 2168                                     "residual\n", st->sc_dev.dv_xname, info);
 2169 
 2170                         /*
 2171                          * This quirk code helps the drive read
 2172                          * the first tape block, regardless of
 2173                          * format.  That is required for these
 2174                          * drives to return proper MODE SENSE
 2175                          * information.
 2176                          */
 2177                         if ((st->quirks & ST_Q_SENSE_HELP) &&
 2178                             (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0)
 2179                                 st->blksize -= 512;
 2180                         else if ((st->flags & ST_POSUPDATED) == 0) {
 2181                                 if (st->blkno != (daddr_t) -1) {
 2182                                         st->blkno +=
 2183                                             (xs->datalen / st->blksize);
 2184                                         st->flags |= ST_POSUPDATED;
 2185                                 }
 2186                         }
 2187                 }
 2188                 /*
 2189                  * If data wanted and no data was transferred, do it immediately
 2190                  */
 2191                 if (xs->datalen && xs->resid >= xs->datalen) {
 2192                         if (st->flags & ST_EIO_PENDING)
 2193                                 return (EIO);
 2194                         if (st->flags & ST_AT_FILEMARK) {
 2195                                 if (bp)
 2196                                         bp->b_resid = xs->resid;
 2197                                 return (0);
 2198                         }
 2199                 }
 2200         } else {                /* must be variable mode */
 2201                 if (bp) {
 2202                         st->last_io_resid = xs->resid;
 2203                 } else {
 2204                         st->last_ctl_resid = xs->resid;
 2205                 }
 2206                 if (sense->flags & SSD_EOM) {
 2207                         /*
 2208                          * The current semantics of this
 2209                          * driver requires EOM detection
 2210                          * to return EIO unless early
 2211                          * warning detection is enabled
 2212                          * for variable mode (this is always
 2213                          * on for fixed block mode).
 2214                          */
 2215                         if (st->flags & ST_EARLYWARN) {
 2216                                 st->flags |= ST_EOM_PENDING;
 2217                                 retval = 0;
 2218                         } else {
 2219                                 retval = EIO;
 2220                         }
 2221 
 2222                         /*
 2223                          * If it's an unadorned EOM detection,
 2224                          * suppress printing an error.
 2225                          */
 2226                         if (key == SKEY_NO_SENSE) {
 2227                                 doprint = 0;
 2228                         }
 2229                 } else if (sense->flags & SSD_FILEMARK) {
 2230                         retval = 0;
 2231                         if (st->fileno != (daddr_t) -1) {
 2232                                 st->fileno++;
 2233                                 st->blkno = 0;
 2234                                 st->flags |= ST_POSUPDATED;
 2235                         }
 2236                 } else if (sense->flags & SSD_ILI) {
 2237                         if (info < 0) {
 2238                                 /*
 2239                                  * The tape record was bigger than the read
 2240                                  * we issued.
 2241                                  */
 2242                                 if ((xs->xs_control & XS_CTL_SILENT) == 0) {
 2243                                         printf("%s: %d-byte tape record too big"
 2244                                             " for %d-byte user buffer\n",
 2245                                             st->sc_dev.dv_xname,
 2246                                             xs->datalen - info, xs->datalen);
 2247                                 }
 2248                                 retval = EIO;
 2249                         } else {
 2250                                 retval = 0;
 2251                                 if (st->blkno != (daddr_t) -1) {
 2252                                         st->blkno++;
 2253                                         st->flags |= ST_POSUPDATED;
 2254                                 }
 2255                         }
 2256                 }
 2257                 if (bp)
 2258                         bp->b_resid = info;
 2259         }
 2260 
 2261 #ifndef SCSIPI_DEBUG
 2262         if (retval == 0 && key == SKEY_NO_SENSE)
 2263                 doprint = 0;
 2264 #endif
 2265         if (key == SKEY_BLANK_CHECK) {
 2266                 /*
 2267                  * This quirk code helps the drive read the
 2268                  * first tape block, regardless of format.  That
 2269                  * is required for these drives to return proper
 2270                  * MODE SENSE information.
 2271                  */
 2272                 if ((st->quirks & ST_Q_SENSE_HELP) &&
 2273                     (periph->periph_flags & PERIPH_MEDIA_LOADED) == 0) {
 2274                         /* still starting */
 2275                         st->blksize -= 512;
 2276                 } else if (!(st->flags & (ST_2FM_AT_EOD | ST_BLANK_READ))) {
 2277                         st->flags |= ST_BLANK_READ;
 2278                         xs->resid = xs->datalen;
 2279                         if (bp) {
 2280                                 bp->b_resid = xs->resid;
 2281                                 /* return an EOF */
 2282                         }
 2283                         retval = 0;
 2284                         /* lost position */
 2285                         st->fileno = st->blkno = -1;
 2286                 }
 2287         }
 2288 
 2289         /*
 2290          * If generic sense processing will continue, we should not
 2291          * print sense info here.
 2292          */
 2293         if (retval == EJUSTRETURN)
 2294                 doprint = 0;
 2295 
 2296         if (doprint) {
 2297 #ifdef  SCSIVERBOSE
 2298                 scsipi_print_sense(xs, 0);
 2299 #else
 2300                 scsipi_printaddr(periph);
 2301                 printf("Sense Key 0x%02x", key);
 2302                 if ((sense->response_code & SSD_RCODE_VALID) != 0) {
 2303                         switch (key) {
 2304                         case SKEY_NOT_READY:
 2305                         case SKEY_ILLEGAL_REQUEST:
 2306                         case SKEY_UNIT_ATTENTION:
 2307                         case SKEY_DATA_PROTECT:
 2308                                 break;
 2309                         case SKEY_VOLUME_OVERFLOW:
 2310                         case SKEY_BLANK_CHECK:
 2311                                 printf(", requested size: %d (decimal)", info);
 2312                                 break;
 2313                         case SKEY_ABORTED_COMMAND:
 2314                                 if (xs->xs_retries)
 2315                                         printf(", retrying");
 2316                                 printf(", cmd 0x%x, info 0x%x",
 2317                                     xs->cmd->opcode, info);
 2318                                 break;
 2319                         default:
 2320                                 printf(", info = %d (decimal)", info);
 2321                         }
 2322                 }
 2323                 if (sense->extra_len != 0) {
 2324                         int n;
 2325                         printf(", data =");
 2326                         for (n = 0; n < sense->extra_len; n++)
 2327                                 printf(" %02x", sense->csi[n]);
 2328                 }
 2329                 printf("\n");
 2330 #endif
 2331         }
 2332         return (retval);
 2333 }
 2334 
 2335 /*
 2336  * The quirk here is that the drive returns some value to st_mode_sense
 2337  * incorrectly until the tape has actually passed by the head.
 2338  *
 2339  * The method is to set the drive to large fixed-block state (user-specified
 2340  * density and 1024-byte blocks), then read and rewind to get it to sense the
 2341  * tape.  If that doesn't work, try 512-byte fixed blocks.  If that doesn't
 2342  * work, as a last resort, try variable- length blocks.  The result will be
 2343  * the ability to do an accurate st_mode_sense.
 2344  *
 2345  * We know we can do a rewind because we just did a load, which implies rewind.
 2346  * Rewind seems preferable to space backward if we have a virgin tape.
 2347  *
 2348  * The rest of the code for this quirk is in ILI processing and BLANK CHECK
 2349  * error processing, both part of st_interpret_sense.
 2350  */
 2351 static int
 2352 st_touch_tape(struct st_softc *st)
 2353 {
 2354         char *bf;
 2355         int readsize;
 2356         int error;
 2357 
 2358         bf = malloc(1024, M_TEMP, M_NOWAIT);
 2359         if (bf == NULL)
 2360                 return (ENOMEM);
 2361 
 2362         if ((error = st->ops(st, ST_OPS_MODESENSE, 0)) != 0)
 2363                 goto bad;
 2364 
 2365         /*
 2366          * If the block size is already known from the
 2367          * sense data, use it. Else start probing at 1024.
 2368          */
 2369         if (st->media_blksize > 0)
 2370                 st->blksize = st->media_blksize;
 2371         else
 2372                 st->blksize = 1024;
 2373 
 2374         do {
 2375                 switch (st->blksize) {
 2376                 case 512:
 2377                 case 1024:
 2378                         readsize = st->blksize;
 2379                         st->flags |= ST_FIXEDBLOCKS;
 2380                         break;
 2381                 default:
 2382                         readsize = 1;
 2383                         st->flags &= ~ST_FIXEDBLOCKS;
 2384                 }
 2385                 if ((error = st->ops(st, ST_OPS_MODESELECT, XS_CTL_SILENT))
 2386                     != 0) {
 2387                         /*
 2388                          * The device did not agree with the proposed
 2389                          * block size. If we exhausted our options,
 2390                          * return failure, else try another.
 2391                          */
 2392                         if (readsize == 1)
 2393                                 goto bad;
 2394                         st->blksize -= 512;
 2395                         continue;
 2396                 }
 2397                 st_read(st, bf, readsize, XS_CTL_SILENT);       /* XXX */
 2398                 if ((error = st_rewind(st, 0, 0)) != 0) {
 2399 bad:                    free(bf, M_TEMP);
 2400                         return (error);
 2401                 }
 2402         } while (readsize != 1 && readsize > st->blksize);
 2403 
 2404         free(bf, M_TEMP);
 2405         return (0);
 2406 }
 2407 
 2408 static int
 2409 stdump(dev_t dev, daddr_t blkno, caddr_t va,
 2410     size_t size)
 2411 {
 2412 
 2413         /* Not implemented. */
 2414         return (ENXIO);
 2415 }

Cache object: 29ccb9744ed0c2def6d6d26f30fff3ea


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