rescan-scsi-bus.sh: harden code

git-svn-id: svn://localhost/trunk@681 6180dd3e-e324-4e3e-922d-17de1ae2f315

Author: doug-gilbert

CREDITS

@@ -6,6 +6,9 @@ Andries Brouwer <aebr at win dot tue dot nl> rewrite of isosize (original
         written by Joerg Schilling). isosize is now found in the util-linux
         package and in the archive directory of this package.
 
+Bart Van Assche <bart dot vanassche at sandisk dot com>
+        harden (improve) code in rescan-scsi-bus.sh [20160224]
+
 Brian Bunker <Brian dot Bunker at netapp dot com> contributed
         sg_read_block_limits and the target reset addition to sg_reset
         [20090615]
@@ -135,4 +138,4 @@ Trent Piepho <xyzzy at speakeasy dot org> print out some "sense key specific"
 
 
 Douglas Gilbert
-17th February 2015
+28th February 2016

ChangeLog

@@ -2,13 +2,14 @@ Each utility has its own version number, date of last change and
 some description at the top of its ".c" file. All utilities in the main
 directory have their own "man" pages. There is also a sg3_utils man page.
 
-Changelog for sg3_utils-1.43 [20160226] [svn: r680]
+Changelog for sg3_utils-1.43 [20160228] [svn: r681]
   - sg_senddiag: add --timeout=SEC option
   - sg_sanitize: add --timeout=SEC option
   - sg_format: add --timeout=SEC option
   - sg_reassign+sg_write_same: fix ULONG_MAX problem
   - sg_turs+sg_requests: make both accept '--num=NUM'
     and '--number=NUM' for mutual compatibility
+  - rescan-scsi-bus.sh: harden code
   - shellcheck cleanup on scripts
 
 Changelog for sg3_utils-1.42 [20160217] [svn: r663]

doc/sg3_utils.8

@@ -4,8 +4,8 @@ sg3_utils \- a package of utilities for sending SCSI commands
 .SH SYNOPSIS
 .B sg_*
 [\fI\-\-enumerate\fR] [\fI\-\-help\fR] [\fI\-\-hex\fR] [\fI\-\-in=FN\fR]
-[\fI\-\-maxlen=LEN\fR] [\fI\-\-raw\fR] [\fI\-\-verbose\fR] [\fI\-\-version\fR]
-[\fIOTHER_OPTIONS\fR]
+[\fI\-\-maxlen=LEN\fR] [\fI\-\-raw\fR] [\fI\-\-timeout=SEC\fR]
+[\fI\-\-verbose\fR] [\fI\-\-version\fR] [\fIOTHER_OPTIONS\fR]
 \fIDEVICE\fR
 .SH DESCRIPTION
 .\" Add any additional description here
@@ -425,6 +425,28 @@ SCSI command, use this option. Alernatively the \fI\-\-in=FN\fR option causes
 from a file named \fIFN\fR. In these cases this option may indicate that
 binary data can be read from stdin or from a nominated file (e.g. \fIFN\fR).
 .TP
+\fB\-t\fR, \fB\-\-timeout\fR=\fISEC\fR
+utilities that issue potentially long\-running SCSI commands often have a
+\fI\-\-timeout=SEC\fR option. This typically instructs the operating system
+to abort the SCSI command in question once the timeout expires. Aborting
+SCSI commands is typically a messy business and in the case of format like
+commands may leave the device in a "format corrupt" state requiring another
+long\-running re\-initialization command to be sent. The argument, \fISEC\fR,
+is usually in seconds and the short form of the option may be something
+other than \fI\-t\fR since the timeout option was typically added later as
+storage devices grew in size and initialization commands took longer. Since
+many utilities had relatively long internal command timeouts before this
+option was introduced, the actual command timeout given to the operating
+systems is the higher of the internal timeout and \fISEC\fR.
+.br
+Many long running SCSI commands have an IMMED bit which causes the command
+to finish relatively quickly but the initialization process to continue. In
+such cases the REQUEST SENSE command can be used to monitor progress with
+its progress indication field (see the sg_requests and sg_turs utilities).
+Utilities that send such SCSI command either have an \fI\-\-immed\fR option
+or a \fI\-\-wait\fR option which is the logical inverse of the "immediate"
+action.
+.TP
 \fB\-v\fR, \fB\-\-verbose\fR
 increase the level of verbosity, (i.e. debug output). Can be used multiple
 times to further increase verbosity. The additional output is usually sent

scripts/rescan-scsi-bus.sh

@@ -1,11 +1,10 @@
 #!/bin/bash
-# Skript to rescan SCSI bus, using the 
-# scsi add-single-device mechanism
+# Script to rescan SCSI bus, using the scsi add-single-device mechanism.
 # (c) 1998--2010 Kurt Garloff <[email protected]>, GNU GPL v2 or v3
 # (c) 2006--2015 Hannes Reinecke, GNU GPL v2 or later
 # $Id: rescan-scsi-bus.sh,v 1.57 2012/03/31 14:08:48 garloff Exp $
 
-VERSION="20160201"
+VERSION="20160228"
 SCAN_WILD_CARD=4294967295
 
 setcolor ()
@@ -44,11 +43,10 @@ print_and_scroll_back ()
   return $LN
 }
 
-# Overwrite a text of length $1 (fallback to $LN) with whitespace
+# Overwrite a text of length $LN with whitespace
 white_out ()
 {
   BK=""; WH=""
-  if test -n "$1"; then LN=$1; fi
   declare -i cntr=0
   while test $cntr -lt $LN; do BK="$BK\e[D"; WH="$WH "; let cntr+=1; done
   echo -en "$WH$BK"
@@ -91,8 +89,8 @@ findhosts ()
       if test $name = add_map -o $name = map -o $name = mod_parm; then continue; fi
       num=$name
       driverinfo=$driver
-      if test -r $hostdir/status; then
-        num=$(printf '%d\n' `sed -n 's/SCSI host number://p' $hostdir/status`)
+      if test -r "$hostdir/status"; then
+        num=$(printf '%d\n' "$(sed -n 's/SCSI host number://p' "$hostdir/status")")
         driverinfo="$driver:$name"
       fi
       hosts="$hosts $num"
@@ -168,17 +166,19 @@ $SCSITMP"
     fi
   else
     grepstr="scsi$host Channel: $CHANNEL Id: $ID Lun: $LUN"
-    SCSISTR=`cat /proc/scsi/scsi | grep -A$LN -e"$grepstr"`
+    SCSISTR=$(grep -A "$LN" -e "$grepstr" /proc/scsi/scsi)
   fi
   if test -z "$SCSISTR"; then return 1; else return 0; fi
 }
 
 # Find sg device with 2.6 sysfs support
 sgdevice26 ()
 {
-  if test -e /sys/class/scsi_device/$host\:$channel\:$id\:$lun/device/generic; then
-    SGDEV=`readlink /sys/class/scsi_device/$host\:$channel\:$id\:$lun/device/generic`
-    SGDEV=`basename $SGDEV`
+  local gendev
+
+  gendev=/sys/class/scsi_device/${host}:${channel}:${id}:${lun}/device/generic
+  if test -e "$gendev"; then
+    SGDEV=$(basename "$(readlink "$gendev")")
   else
     for SGDEV in /sys/class/scsi_generic/sg*; do
       DEV=`readlink $SGDEV/device`
@@ -213,7 +213,7 @@ sgdevice ()
       DRV=`grep 'Attached drivers:' /proc/scsi/scsi 2>/dev/null`
       if [ $? = 1 ]; then return; fi
     fi
-    if ! `echo $DRV | grep 'drivers: sg' >/dev/null`; then
+    if ! echo "$DRV" | grep -q 'drivers: sg'; then
       modprobe sg
     fi
     sgdevice24
@@ -223,14 +223,37 @@ sgdevice ()
   fi
 }
 
+# Whether or not the RMB (removable) bit has been set in the INQUIRY response.
+# Uses ${host}, ${channel}, ${id} and ${lun}. Assumes that sg_device() has
+# already been called. How to test this function: copy/paste this function
+# in a shell and run
+# (cd /sys/class/scsi_device && for d in *; do set ${d//:/ }; echo -n "$d $(</sys/class/scsi_device/${d}/device/block/*/removable) <> "; SGDEV=bsg/$d host=$1 channel=$2 id=$3 lun=$4 is_removable; done)
+is_removable ()
+{
+  local b p
+
+  p=/sys/class/scsi_device/${host}:${channel}:${id}:${lun}/device/inquiry
+  # Extract the second byte of the INQUIRY response and check bit 7 (mask 0x80).
+  b=$(od -tx1 -j1 -N1 "$p" 2>/dev/null |
+           { read -r offset byte rest; echo -n "$byte"; })
+  if [ -n "$b" ]; then
+    echo $(((0x$b & 0x80) != 0))
+  else
+    sg_inq /dev/$SGDEV 2>/dev/null | sed -n 's/^.*RMB=\([0-9]*\).*$/\1/p'
+  fi
+}
+
 # Test if SCSI device is still responding to commands
 # Return values:
 #   0 device is present
 #   1 device has changed
 #   2 device has been removed
 testonline ()
 {
+  local ctr RC RMB
+
   : testonline
+  ctr=0
   RC=0
   # Set default values
   IPTYPE=31
@@ -250,7 +273,7 @@ testonline ()
     RC=$?
     # Check for removable device; TEST UNIT READY obviously will
     # fail for a removable device with no medium
-    RMB=`sg_inq /dev/$SGDEV 2>/dev/null | grep 'RMB=' | sed 's/^.*RMB=\(.\).*$/\1/'`
+    RMB=$(is_removable)
     print_and_scroll_back "$host:$channel:$id:$lun $SGDEV ($RMB) "
     test $RC = 2 -a "$RMB" = "1" && break
   done
@@ -296,7 +319,7 @@ testonline ()
   return $RC
 }
 
-# Test if SCSI device $host $channen $id $lun exists
+# Test if SCSI device $host $channel $id $lun exists
 # Outputs description from /proc/scsi/scsi (unless arg passed)
 # Returns SCSISTR (empty if no dev)
 testexist ()
@@ -382,7 +405,7 @@ getluns()
   if test $? != 0 -o -z "$LLUN"; then echo 0; return 1; fi
   for lun in $LLUN ; do
       # Swap LUN number
-      l0=$(printf '%u' 0x$lun)
+      l0=0x$lun
       l1=$(( ($l0 >> 48) & 0xffff ))
       l2=$(( ($l0 >> 32) & 0xffff )) 
       l3=$(( ($l0 >> 16) & 0xffff ))
@@ -562,8 +585,7 @@ doreportlun()
   REPLUNSTAT=$?
   lunremove=
   #echo "getluns reports " $targetluns
-  olddev=`find /sys/class/scsi_device/ -name $host:$channel:$id:* 2>/dev/null | sort -t: -k4 -n`
-  oldluns=`echo "$olddev" | awk -F'/' '{print $5}' | awk -F':' '{print $4}'`
+  olddev=`find /sys/class/scsi_device/ -name "$host:$channel:$id:*" 2>/dev/null | sort -t: -k4 -n`
   oldtargets="$targetluns"
   # OK -- if we don't have a LUN to send a REPORT_LUNS to, we could
   # fall back to wildcard scanning. Same thing if the device does not
@@ -577,7 +599,7 @@ doreportlun()
     else
       echo "scsi add-single-device $host $channel $id $SCAN_WILD_CARD" > /proc/scsi/scsi
     fi
-    targetluns=`find /sys/class/scsi_device/ -name $host:$channel:$id:* 2>/dev/null | awk -F'/' '{print $5}' | awk -F':' '{print $4}' | sort -n`
+    targetluns=`find /sys/class/scsi_device/ -name "$host:$channel:$id:*" 2>/dev/null | awk -F'/' '{print $5}' | awk -F':' '{print $4}' | sort -n`
     let found+=`echo "$targetluns" | wc -l`
     let found-=`echo "$olddev" | wc -l`
   fi
@@ -701,8 +723,6 @@ findremapped()
   local sddev=
   local id_serial=
   local id_serial_old=
-  local sysfs_devpath=
-  local mpath_uuid=
   local remapped=
   mpaths=""
   local tmpfile=$(mktemp /tmp/rescan-scsi-bus.XXXXXXXX 2> /dev/null)
@@ -862,13 +882,13 @@ findmultipath()
   local maj_min=`cat /sys/block/$dev/dev`
   for mp in $($DMSETUP ls --target=multipath | cut -f 1) ; do
     [ "$mp" = "No" ] && break;
-    if $($DMSETUP status $mp | grep -q " $maj_min ") ; then
+    if $DMSETUP status $mp | grep -q " $maj_min "; then
       # With two arguments, look up current uuid from sysfs
       # if it doesn't match what was passed, this multipath
       # device is not updated, so this is a remapped LUN
       if [ -n "$find_mismatch" ] ; then
-        mp2=`$MULTIPATH -l $mp | egrep -o dm-[0-9]+`
-        mp2=`cat /sys/block/$mp2/dm/uuid | cut -f2 -d-`
+        mp2=$($MULTIPATH -l "$mp" | egrep -o "dm-[0-9]+")
+        mp2=$(cut -f2 -d- "/sys/block/$mp2/dm/uuid")
         if [ "$find_mismatch" != "$mp2" ] ; then
           addmpathtolist $mp
           found_dup=1