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[src/trunk]: src/sys/dev/scsipi Fix PR kern/53949:



details:   https://anonhg.NetBSD.org/src/rev/0b437a909fa2
branches:  trunk
changeset: 448873:0b437a909fa2
user:      kardel <kardel%NetBSD.org@localhost>
date:      Tue Feb 12 13:43:40 2019 +0000

description:
Fix PR kern/53949:

Fix inconsistent/incomplete file mark handling to conform again
to mtio(4) at close(2) time. This was necessary as the PREVENT/ALLOW
bracket was reduced from a whole mount session to cover only the
open(2)/close(2) time on ~2002-03-22. The rationale was to allow
robots and humans to change the media during a mount session.

Unfortunately this lead to file marks being written to potentially other
media at the beginning on drives that used the two file marks as EOM
pattern. In order for that to happen the media had to be removed after
data and at most one file mark had been written before removal.

The mount error message has been clarified and a warning about
potential data/file mark lossage on UNIT ATTENTION
during an active mount session with unfinished file marks has been
added.

While there, fix, but disable the commented SUN compatibility to write
final file marks by opening and immediately closing the device
in O_WRONLY mode. That code has not been working since around 1998.
It can now be enabled with options ST_SUNCOMPAT.

Additionally debug output coverage has been extended.

diffstat:

 sys/dev/scsipi/st.c |  94 ++++++++++++++++++++++++++++++++++++++++++++--------
 1 files changed, 79 insertions(+), 15 deletions(-)

diffs (190 lines):

diff -r 9326cd62e4cc -r 0b437a909fa2 sys/dev/scsipi/st.c
--- a/sys/dev/scsipi/st.c       Tue Feb 12 12:52:49 2019 +0000
+++ b/sys/dev/scsipi/st.c       Tue Feb 12 13:43:40 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: st.c,v 1.235 2019/02/03 03:19:28 mrg Exp $ */
+/*     $NetBSD: st.c,v 1.236 2019/02/12 13:43:40 kardel Exp $ */
 
 /*-
  * Copyright (c) 1998, 2004 The NetBSD Foundation, Inc.
@@ -50,7 +50,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: st.c,v 1.235 2019/02/03 03:19:28 mrg Exp $");
+__KERNEL_RCSID(0, "$NetBSD: st.c,v 1.236 2019/02/12 13:43:40 kardel Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_scsi.h"
@@ -615,8 +615,30 @@
                 */
                if ((st->flags & ST_MOUNTED) || ST_MOUNT_DELAY == 0 ||
                    (st->mt_key != SKEY_NOT_READY)) {
-                       device_printf(st->sc_dev, "mount error (key=%d)\n",
-                               st->mt_key);
+                       device_printf(st->sc_dev,
+                                     "mount error (sense key=%d) - "
+                                     "terminating mount session\n",
+                                     st->mt_key);
+                       /*
+                        * the following should not trigger unless
+                        * something serious happened while the device
+                        * was open (PREVENT MEDIUM REMOVAL in effect)
+                        */
+                       if (st->flags & ST_WRITTEN &&
+                           st->mt_key == SKEY_UNIT_ATTENTION) {
+                               /*
+                                * device / media state may have changed
+                                * refrain from writing missing file marks
+                                * onto potentially newly inserted/formatted
+                                * media (e. g. emergency EJECT/RESET/etc.)
+                                */
+                               st->flags &= ~(ST_WRITTEN|ST_FM_WRITTEN);
+
+                               device_printf(st->sc_dev,
+                                    "CAUTION: file marks/data may be missing"
+                                    " - ASC = 0x%02x, ASCQ = 0x%02x\n",
+                                             st->asc, st->ascq);
+                       }
                        goto bad;
                }
 
@@ -727,15 +749,30 @@
         */
 
        stxx = st->flags & (ST_WRITTEN | ST_FM_WRITTEN);
-       if (((flags & FWRITE) && stxx == ST_WRITTEN) ||
-           ((flags & O_ACCMODE) == FWRITE && stxx == 0)) {
-               int nm;
+       if ((flags & FWRITE) != 0) {
+               int nm = 0;
+#ifdef ST_SUNCOMPAT
+               /*
+                * on request only
+                * original compat code has not been working
+                * since ~1998
+                */
+               if ((flags & O_ACCMODE) == FWRITE && (stxx == 0)) {
+                       st->flags |= ST_WRITTEN;
+                       SC_DEBUG(st->sc_periph, SCSIPI_DB3,
+                                ("SUN compatibility: write FM(s) at close\n"));
+               }
+#endif
                error = st_check_eod(st, FALSE, &nm, 0);
+               SC_DEBUG(st->sc_periph, SCSIPI_DB3,
+                        ("wrote %d FM(s) at close error=%d\n", nm, error));
        }
 
        /* Allow robots to eject tape if needed.  */
-       scsipi_prevent(periph, SPAMR_ALLOW,
-           XS_CTL_IGNORE_ILLEGAL_REQUEST | XS_CTL_IGNORE_NOT_READY);
+       if (!(st->quirks & ST_Q_NOPREVENT)) {
+               scsipi_prevent(periph, SPAMR_ALLOW,
+                   XS_CTL_IGNORE_ILLEGAL_REQUEST | XS_CTL_IGNORE_NOT_READY);
+       }
 
        switch (STMODE(dev)) {
        case NORMAL_MODE:
@@ -769,18 +806,28 @@
                         * If both statements are true, then we backspace
                         * one filemark.
                         */
+                       stxx &= ~ST_FM_WRITTEN;
                        stxx |= (st->flags & ST_2FM_AT_EOD);
                        if ((flags & FWRITE) != 0 &&
                            (stxx == (ST_2FM_AT_EOD|ST_WRITTEN))) {
                                error = st_space(st, -1, SP_FILEMARKS, 0);
+                               SC_DEBUG(st->sc_periph, SCSIPI_DB3, ("st_space(-1) error=%d\n", error));
+                       } else {
+                               SC_DEBUG(st->sc_periph, SCSIPI_DB3, ("no backspacing - flags = 0x%x, stxx=0x%x, st->flags=0x%x\n", flags, stxx, st->flags));
                        }
+               } else {
+                       SC_DEBUG(st->sc_periph, SCSIPI_DB3, ("error %d from st_check_eod\n", error));
                }
+       
                break;
        case EJECT_MODE:
                st_unmount(st, EJECT);
                break;
        }
 
+       KASSERTMSG((st->flags & ST_WRITTEN) == 0,
+                  "pending ST_WRITTEN flag NOT cleared (flags=0x%x)", st->flags);
+       
        scsipi_wait_drain(periph);
 
        scsipi_adapter_delref(adapt);
@@ -908,7 +955,7 @@
 
        /*
         * Section 9.3.3 of the SCSI specs states that a device shall return
-        * the density value specified in the last succesfull MODE SELECT
+        * the density value specified in the last successful MODE SELECT
         * after an unload operation, in case it is not able to
         * automatically determine the density of the new medium.
         *
@@ -1066,6 +1113,8 @@
 
        /* If offset is negative, error */
        if (bp->b_blkno < 0) {
+               SC_DEBUG(periph, SCSIPI_DB3,
+                        ("EINVAL: ststrategy negative blockcount %ld\n", bp->b_blkno));
                bp->b_error = EINVAL;
                goto abort;
        }
@@ -1363,8 +1412,12 @@
 {
        struct st_softc *st = device_lookup_private(&st_cd, STUNIT(dev));
 
-       return physio(ststrategy, NULL, dev, B_READ,
-           st->sc_periph->periph_channel->chan_adapter->adapt_minphys, uio);
+       int r = physio(ststrategy, NULL, dev, B_READ,
+                      st->sc_periph->periph_channel->chan_adapter->adapt_minphys, uio);
+
+       SC_DEBUG(st->sc_periph, SCSIPI_DB1, ("[stread: result=%d]\n", r));
+
+       return r;
 }
 
 static int
@@ -1372,8 +1425,12 @@
 {
        struct st_softc *st = device_lookup_private(&st_cd, STUNIT(dev));
 
-       return physio(ststrategy, NULL, dev, B_WRITE,
+       int r = physio(ststrategy, NULL, dev, B_WRITE,
            st->sc_periph->periph_channel->chan_adapter->adapt_minphys, uio);
+
+       SC_DEBUG(st->sc_periph, SCSIPI_DB1, ("[stwrite: result=%d]\n", r));
+
+       return r;
 }
 
 /*
@@ -1786,8 +1843,12 @@
         * It's hard to write a negative number of file marks.
         * Don't try.
         */
-       if (number < 0)
+       if (number < 0) {
+               SC_DEBUG(st->sc_periph, SCSIPI_DB3,
+                        ("EINVAL: st_write_filemarks not writing %d file marks\n", number));
                return EINVAL;
+       }
+       
        switch (number) {
        case 0:         /* really a command to sync the drive's buffers */
                break;
@@ -1982,8 +2043,11 @@
                        printf("%02x ", posdata[hard] & 0xff);
                printf("\n");
 #endif
-               if (posdata[0] & 0x4)   /* Block Position Unknown */
+               if (posdata[0] & 0x4) { /* Block Position Unknown */
+                       SC_DEBUG(st->sc_periph, SCSIPI_DB3,
+                                ("EINVAL: strdpos block position unknown\n"));
                        error = EINVAL;
+               }       
                else
                        *blkptr = _4btol(&posdata[4]);
        }



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