backup/remountrocp

   1 #!/bin/bash
   2 # invoked by backup scripts as
   3 #    remountrocp snap $vardir $device $mountpoint
   4 #               remounts $mountpoint readonly
   5 #               copies data to $vardir/snap-mount
   6 #               remounts $mountpoint readwrite
   7 #    remountrocp drop $vardir
   8 #               deletes $vardir/snap-mount
   9
  10 set -e
  11 snapkind=remountrocp
  12 : ${lvm_vg:=}
  13 remountrocp_fs=ext2
  14 . ${CHIARK_BACKUP_SHAREDIR:-/usr/share/chiark-backup}/snap-common
  15
  16 #---------- clean up anything
  17
  18 vgroup=$lvm_vg
  19 lvmdropcore
  20
  21 lastsettings="$vardir/remountrocp-settings"
  22 test ! -f $lastsettings || . $lastsettings
  23
  24 if test "$opmode" = drop; then
  25         test -z "$last_mountpoint" || mount -o remount,rw $last_mountpoint
  26         rm -f $lastsettings
  27         echo 'remountrocp snap dropped'
  28         exit 0
  29 fi
  30
  31 #---------- create snapshot
  32
  33 if [ -z "$lvm_lvsize_opts" ]; then
  34         lvmextentscore1
  35
  36         df_out="$(really df -P --block-size=$extsize $mountpoint)"
  37         extents2="$(printf "%s" "$df_out" | awk '/^\// {print $3}')"
  38         extents2=$(( ($extents2*150+102399)/102400 + 4 ))
  39
  40         lvmextentscore2
  41 fi
  42
  43 lvmcreatecore1
  44
  45 cat >$lastsettings.new <<END
  46 last_mountpoint=$mountpoint
  47 END
  48 mv -f $lastsettings.new $lastsettings
  49
  50 lvcreate \
  51         $lvm_lvtools_opts \
  52         $lvm_lvsize_opts \
  53         -n $lvm_lv \
  54         $lvm_lvcreate_opts \
  55         $vgroup \
  56         $lvm_lvcreate_args
  57
  58 mkfs -t $remountrocp_fs -q "$lvpath"
  59
  60 mkdir -- "$snmnt"
  61 mount -t $remountrocp_fs $lvm_mount_opts "$lvpath" "$snmnt"
  62 echo ' copy filesystem created and mounted'
  63
  64 attempts=10
  65 while true; do
  66         if mount -o remount,ro "$mountpoint"; then break; fi
  67         attempts=$(( $attempts - 1 ))
  68         if [ $attempts = 0 ]; then
  69                 echo >&2 'cannot remount readonly'
  70                 exit 1
  71         fi
  72         sleep 1
  73 done
  74 trap "set +e; mount -o remount,rw $mountpoint; exit 12" 0
  75 echo ' source remounted readonly, copying...'
  76 cp -ax -- "$mountpoint/." "$snmnt/."
  77 echo ' finalising...'
  78 mount -o remount,rw "$mountpoint"
  79 trap '' 0
  80 mount -o remount,ro "$lvpath"
  81
  82 echo 'remountrocp snap activated'