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Make it work specifically for the default btrfs structure
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in SLE12-SP1, see #556
Basically this means:
Recovery of btrfs snapshot subvolumes is still not possible.
Only recovery of "normal" btrfs subvolumes is possible.
On SLE12-SP1 the only exception is the btrfs snapshot subvolume
that is mounted at '/' but that one is not recreated but instead
it is created anew from scratch during the recovery installation with the
default first btrfs snapper snapshot subvolume path "@/.snapshots/1/snapshot"
by the SUSE tool "installation-helper --step 1".
Other snapshots like "@/.snapshots/234/snapshot" are not recreated.
Additionally for mounted btrfs subvolumes that have the 'no copy on write'
attribute set those btrfs subvolumes are recreated with that attribute set.
Some details:
On SLE12-SP1 with default btrfs subvolumes what is mounted at '/'
is a btrfs snapshot subvolume that is controlled by snapper
so that snapper is needed in the recovery system. Snapper setup
by the recovery system uses /usr/lib/snapper/installation-helper
via "installation-helper --step 1" that creates a snapper config
based on /etc/snapper/config-templates/default
In SLE12-SP1 some btrfs subvolume directories (/var/lib/pgsql
/var/lib/libvirt/images /var/lib/mariadb) have the
"no copy on write (C)" file attribute set so that chattr is required
in the recovery system and accordingly also lsattr is useful to have
in the recovery system (but not strictly required).
Therefore in /etc/rear/local.conf the following is needed:
REQUIRED_PROGS=( "${REQUIRED_PROGS[@]}" snapper chattr lsattr )
COPY_AS_IS=( "${COPY_AS_IS[@]}" /usr/lib/snapper/installation-helper /etc/snapper/config-templates/default )
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@jsmeix
jsmeix committed Nov 2, 2015
1 parent 829925c commit 307b98c
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Showing 3 changed files with 163 additions and 17 deletions.
23 changes: 20 additions & 3 deletions usr/share/rear/layout/prepare/GNU/Linux/13_include_mount_filesystem_code.sh
View file
Expand Up @@ -14,14 +14,31 @@ mount_fs() {

# Extract mount options.
local option mountopts
# An input line could look like this (an example from SLES12-SP1):
# fs /dev/sda2 / btrfs uuid=a2b2c3 label= options=rw,relatime,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot
# which means by the above 'read' the variable (that is unfortunately) named 'options' gets the
# value 'options=rw,relatime,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot'
# i.e. options='options=rw,relatime,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot'
for option in $options ; do
name=${option%%=*} # options can contain more '=' signs
value=${option#*=}
name=${option%%=*} # an option can contain more '=' signs (see the above example value)
value=${option#*=} # therefore split the name from the actual value at the leftmost '='

case $name in
(options)
### Do not mount nodev, as chrooting later on would fail.
mountopts=${value//nodev/dev}
value=${value//nodev/dev}
# btrfs mount options like subvolid=259 or subvol=/@/.snapshots/1/snapshot
# from the old system cannot work here for recovery because btrfs subvolumes
# are not yet created (and when created their subvolid is likely different)
# so that those mount options are removed here. All btrfs subvolume handling
# happens in the btrfs_subvolumes_setup function in 13_include_mount_subvolumes_code.sh
# First add a comma at the end so that it is easier to remove a mount option at the end:
value=${value/%/,}
# Remove all subvolid= and subvol= mount options (the extglob shell option is enabled in rear):
value=${value//subvolid=*([^,]),/}
value=${value//subvol=*([^,]),/}
# Remove all commas at the end:
mountopts=${value/%,/}
;;
esac
done
Expand Down
131 changes: 117 additions & 14 deletions usr/share/rear/layout/prepare/GNU/Linux/13_include_mount_subvolumes_code.sh
View file
Expand Up @@ -33,6 +33,35 @@ btrfs_subvolumes_setup() {
# The root of the filesysten tree of the to-be-recovered-system in the recovery system should be in a global variable:
recovery_system_root=/mnt/local
###########################################
# SLES 12 SP1 special btrfs subvolumes setup detection:
SLES12SP1_btrfs_detection_string="@/.snapshots/"
if grep "^btrfsdefaultsubvol $device $mountpoint [0-9]* $SLES12SP1_btrfs_detection_string" "$LAYOUT_FILE" ; then
info_message="Detected SLES 12 SP1 special btrfs subvolumes setup because the default subvolume path contains '$SLES12SP1_btrfs_detection_string'"
Log $info_message
echo "# $info_message" >> "$LAYOUT_CODE"
# For SLES 12 SP1 a btrfsdefaultsubvol entry in disklayout.conf looks like
# btrfsdefaultsubvol /dev/sda2 / 259 @/.snapshots/1/snapshot
# where "@/.snapshots/" should be fixed but "1/snapshot" may vary.
# This requires special setup because the btrfs default subvolume on SLES 12 SP1
# is not a normal btrfs subvolume (as it was on SLES 12 (without SP1))
# but on SLES 12 SP1 it is a snapper controlled btrfs snapshot subvolume, see
# https://github.com/rear/rear/issues/556
# https://fate.suse.com/318701 (SUSE internal feature request)
# https://bugzilla.suse.com/show_bug.cgi?id=946006 (SUSE internal issue)
SLES12SP1_btrfs_subvolumes_setup="yes"
# Because that very special btrfs default subvolume on SLES 12 SP1
# has to be controlled by snapper it must be set up by snapper
# which means that snapper is needed in the rear recovery system.
# For this special setup during installation a special SUSE tool
# /usr/lib/snapper/installation-helper is used:
SLES12SP1_installation_helper_executable="/usr/lib/snapper/installation-helper"
# What "snapper/installation-helper --step 1" basically does is
# creating a snapshot of the first root filesystem
# where the first root filesystem must have the btrfs subvolume '@' mounted at '/'
# which means the btrfs subvolume '@' must be the initial btrfs default subvolume:
SLES12SP1_initial_default_subvolume_path="@"
fi
###########################################
# Btrfs snapshot subvolumes handling:
# Remember all btrfs snapshot subvolumes to exclude them when mounting all btrfs normal subvolumes below.
# The btrfs snapshot subvolumes entries that are created by 23_filesystem_layout.sh
Expand Down Expand Up @@ -66,13 +95,21 @@ btrfs_subvolumes_setup() {
# In contrast after the btrfs default subvolume setup only the btrfs filesystem default subvolume is mounted at the mountpoint and
# then it would be no longer possible to create btrfs subvolumes with the subvolume path that is stored in the LAYOUT_FILE.
# In particular a special btrfs default subvolume (i.e. when the btrfs default subvolume is not the toplevel/root subvolume)
# is also listed as a normal subvolume so that also the subvolume that is later used as default subvolume is hereby created.
# is also listed as a normal subvolume so that also the subvolume that is later used as default subvolume is hereby created
# provided the btrfs default subvolume is not a btrfs snapshot subvolume as in SLES 12 SP1 - but not in SLES 12 (without SP1):
while read dummy dummy dummy dummy subvolume_path junk ; do
# Empty subvolume_path may indicate an error. In this case be verbose and inform the user:
if test -z "$subvolume_path" ; then
LogPrint "btrfsnormalsubvol entry with empty subvolume_path for $device at $mountpoint may indicate an error, skipping subvolume setup for it."
continue
fi
# In case of SLES 12 SP1 special btrfs subvolumes setup
# skip setup of the normal btrfs subvolume '@/.snapshots' because
# that one will be created by "snapper/installation-helper --step 1"
# which fails if it already exists:
if test -n "$SLES12SP1_btrfs_subvolumes_setup" ; then
test "$subvolume_path" = "@/.snapshots" && continue
fi
# When there is a non-empty subvolume_path, btrfs normal subvolume setup is needed:
Log "Setup normal subvolume $subvolume_path for $device at $mountpoint"
# E.g. for 'btrfs subvolume create /foo/bar/subvol' the directory path /foo/bar/ must already exist
Expand All @@ -99,10 +136,20 @@ btrfs_subvolumes_setup() {
fi
echo "btrfs subvolume create $recovery_system_mountpoint/$subvolume_path"
) >> "$LAYOUT_CODE"
# Btrfs subvolumes 'no copy on write' attribute setup:
if grep -q "^btrfsnocopyonwrite $subvolume_path\$" "$LAYOUT_FILE" ; then
info_message="Setting 'no copy on write' attribute for subvolume $subvolume_path"
Log $info_message
(
echo "# $info_message"
echo "chattr +C $recovery_system_mountpoint/$subvolume_path"
) >> "$LAYOUT_CODE"
fi
done < <( grep "^btrfsnormalsubvol $device $mountpoint " "$LAYOUT_FILE" )
###########################################
# Btrfs default subvolume setup:
# There is exactly one default subvolume for one btrfs filesystem on one specific device (usually a harddisk partition like e.g. /dev/sda1):
# No outer 'while read ...' loop because there is exactly one default subvolume for one btrfs filesystem
# on one specific device (usually a harddisk partition like e.g. /dev/sda1):
read dummy dummy dummy dummy subvolume_path junk < <( grep "^btrfsdefaultsubvol $device $mountpoint " "$LAYOUT_FILE" )
# Artificial 'for' clause that is run only once to be able to 'continue' in the same syntactical way as in the 'while' loops
# (because the 'for' loop is run only once 'continue' is the same as 'break'):
Expand All @@ -125,18 +172,46 @@ btrfs_subvolumes_setup() {
echo "# $info_message" >> "$LAYOUT_CODE"
continue
fi
# When in the original system the btrfs filesystem had a special different default subvolume,
# When in the original system the btrfs filesystem had a special different default subvolume
# (i.e. when the btrfs default subvolume is not the toplevel/root subvolume), then
# that different subvolume needs to be set to be the default subvolume:
recovery_system_mountpoint=$recovery_system_root$mountpoint
Log "Setting $subvolume_path as btrfs default subvolume for $device at $mountpoint"
(
echo "# Begin btrfs default subvolume setup on $device at $mountpoint"
echo "# Making the $subvolume_path subvolume the default subvolume"
echo "# Get the ID of the $subvolume_path subvolume"
echo "subvolumeID=\$( btrfs subvolume list -a $recovery_system_mountpoint | sed -e 's/<FS_TREE>\///' | grep ' $subvolume_path\$' | tr -s '[:blank:]' ' ' | cut -d ' ' -f 2 )"
echo "# Set the $subvolume_path subvolume as default subvolume using its subvolume ID"
echo "btrfs subvolume set-default \$subvolumeID $recovery_system_mountpoint"
) >> "$LAYOUT_CODE"
if test -n "$SLES12SP1_btrfs_subvolumes_setup" ; then
(
echo "# Begin btrfs default subvolume setup on $device at $mountpoint"
echo "# Doing special SLES 12 SP1 btrfs default snapper snapshot subvolume setup"
echo "# because the default subvolume path '$subvolume_path' contains '@/.snapshots/'"
echo "# Making the $SLES12SP1_initial_default_subvolume_path subvolume the initial default subvolume"
echo "# Get the ID of the $initial_default_subvolume_path subvolume"
echo "subvolumeID=\$( btrfs subvolume list -a $recovery_system_mountpoint | sed -e 's/<FS_TREE>\///' | grep ' $SLES12SP1_initial_default_subvolume_path\$' | tr -s '[:blank:]' ' ' | cut -d ' ' -f 2 )"
echo "# Set the $SLES12SP1_initial_default_subvolume_path subvolume as initial default subvolume using its subvolume ID"
echo "btrfs subvolume set-default \$subvolumeID $recovery_system_mountpoint"
echo "# Begin step 1 of special SLES 12 SP1 btrfs default snapper snapshot subvolume setup"
echo "umount $recovery_system_mountpoint"
echo "# Configuring snapper for root filesystem - step 1:"
echo "# - temporarily mounting device"
echo "# - copying/modifying config-file"
echo "# - creating filesystem config"
echo "# - creating snapshot of first root filesystem"
echo "# - setting default subvolume"
echo "if test -x $SLES12SP1_installation_helper_executable"
echo "then $SLES12SP1_installation_helper_executable --step 1 --device $device --description 'first root filesystem'"
echo "else LogPrint '$SLES12SP1_installation_helper_executable not executable may indicate an error with btrfs default subvolume setup for $subvolume_path on $device'"
echo "fi"
echo " mount -t btrfs -o subvolid=0 $mountopts $device $recovery_system_mountpoint"
echo "# End step 1 of special SLES 12 SP1 btrfs default snapper snapshot subvolume setup"
) >> "$LAYOUT_CODE"
else
(
echo "# Begin btrfs default subvolume setup on $device at $mountpoint"
echo "# Making the $subvolume_path subvolume the default subvolume"
echo "# Get the ID of the $subvolume_path subvolume"
echo "subvolumeID=\$( btrfs subvolume list -a $recovery_system_mountpoint | sed -e 's/<FS_TREE>\///' | grep ' $subvolume_path\$' | tr -s '[:blank:]' ' ' | cut -d ' ' -f 2 )"
echo "# Set the $subvolume_path subvolume as default subvolume using its subvolume ID"
echo "btrfs subvolume set-default \$subvolumeID $recovery_system_mountpoint"
) >> "$LAYOUT_CODE"
fi
# When the btrfs filesystem has a special default subvolume (one that is not the toplevel/root subvolume)
# then a reasonable assumption is that this one was mounted in the original system and not something else.
# FIXME: It is possible that the admin has actually mounted something else in his original system
Expand Down Expand Up @@ -165,6 +240,18 @@ btrfs_subvolumes_setup() {
fi
# When there are non-empty values, mounting normal subvolume is needed:
Log "Mounting normal subvolume $subvolume_path at $subvolume_mountpoint for $device"
# btrfs mount options like subvolid=259 or subvol=/@/.snapshots/1/snapshot
# from the old system cannot work here or are not needed here for recovery
# because for new created btrfs subvolumes their subvolid is likely different
# and the subvol=... value is already explicitly available via subvolume_path
# so that those mount options are removed here:
# First add a comma at the end so that it is easier to remove a mount option at the end:
subvolume_mount_options=${subvolume_mount_options/%/,}
# Remove all subvolid= and subvol= mount options (the extglob shell option is enabled in rear):
subvolume_mount_options=${subvolume_mount_options//subvolid=*([^,]),/}
subvolume_mount_options=${subvolume_mount_options//subvol=*([^,]),/}
# Remove all commas at the end:
subvolume_mount_options=${subvolume_mount_options/%,/}
# Do not mount btrfs snapshot subvolumes:
for snapshot_subvolume_device_and_path in $snapshot_subvolumes_devices_and_paths ; do
# Assume $snapshot_subvolume_device_and_path is "/dev/sdX99,my/subvolume,path" then split
Expand Down Expand Up @@ -193,9 +280,20 @@ btrfs_subvolumes_setup() {
# On Fedora 21 there is a btrfs subvolume "root" which is mounted at the '/' mountpoint.
# I (jsmeix@suse.de) am not a btrfs expert but from my point of view it looks like
# a misconfiguration (a.k.a. bug) in Fedora 21 how they set up btrfs. I think Fedora
# should specify as btrfs default subvolume what is mounted at the '/' mountpoint.
# Regardless if it is really a misconfiguration or not I like to have rear working fail-safe
# because an admin could manually create such an awkward btrfs setup.
# should specify as btrfs default subvolume what is mounted by default at the '/' mountpoint.
# On the other hand I noticed an openSUSE user who presented arguments that
# the btrfs default subvolume setting only belongs to the user and
# should not be used by the system to specify what is mounted by default,
# see what Chris Murphy wrote on the "Default btrfs subvolume after a rollback"
# and "systemd, btrfs, /var/lib/machines" mail threads on opensuse-factory@opensuse.org
# http://lists.opensuse.org/opensuse-factory/2015-07/msg00517.html
# http://lists.opensuse.org/opensuse-factory/2015-07/msg00591.html
# and his GitHub snapper issue and openSUSE feature request
# "snapper improperly usurps control of the default subvolume from the user"
# https://github.com/openSUSE/snapper/issues/178
# https://features.opensuse.org/319292
# Regardless who or what is right or wrong here I like to have rear working fail-safe
# because an admin could manually create any kind of awkward btrfs setup.
# Therefore remounting is needed when the subvolume_mountpoint is '/'
# but the subvolume_path is neither '/' nor the default subvolume.
# Examples: disklayout.conf contains
Expand All @@ -205,6 +303,11 @@ btrfs_subvolumes_setup() {
# on SLES 12 at '/' the default subvolume '@' is mounted:
# btrfsdefaultsubvol /dev/sda2 / 257 @
# btrfsmountedsubvol /dev/sda2 / rw,relatime,space_cache @
# on SLES 12 SP1 at '/' the default subvolume '@/.snapshots/1/snapshot' is mounted:
# btrfsdefaultsubvol /dev/sda2 / 259 @/.snapshots/1/snapshot
# #btrfssnapshotsubvol /dev/sda2 / 259 @/.snapshots/1/snapshot
# btrfsnormalsubvol /dev/sda2 / 258 @/.snapshots
# btrfsmountedsubvol /dev/sda2 / rw,relatime,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot @/.snapshots/1/snapshot
# on Fedora 21 at '/' not the default subvolume which is the root subvolume (ID 5 '/') but the subvolume 'root' is mounted:
# btrfsdefaultsubvol /dev/sda3 / 5 /
# btrfsmountedsubvol /dev/sda3 / rw,relatime,seclabel,space_cache root
Expand Down
26 changes: 26 additions & 0 deletions usr/share/rear/layout/save/GNU/Linux/23_filesystem_layout.sh
View file
Expand Up @@ -270,6 +270,32 @@ read_filesystems_command="$read_filesystems_command | sort -t ' ' -k 1,1 -u"
echo "btrfsmountedsubvol $device $subvolume_mountpoint $mount_options $btrfs_subvolume_path"
fi
done < <( eval $read_mounted_btrfs_subvolumes_command )
########################################
# No copy on write attributes of mounted btrfs subvolumes:
echo "# Mounted btrfs subvolumes that have the 'no copy on write' attribute set."
echo "# Format: btrfsnocopyonwrite <btrfs_subvolume_path>"
lsattr_command="$( type -P lsattr )"
if test -x "$lsattr_command" -a -x "$findmnt_command" ; then
for subvolume_mountpoint in $( $findmnt_command -nrv -o TARGET -t btrfs ) ; do
# The 'no copy on write' attribute is shown as 'C' in the lsattr output (see "man chattr"):
if $lsattr_command -d $subvolume_mountpoint | cut -d ' ' -f 1 | grep -q 'C' ; then
btrfs_subvolume_path=$( $findmnt_command -nrv -o FSROOT $subvolume_mountpoint )
# Remove leading '/' from btrfs_subvolume_path (except it is only '/') to have same syntax for all entries and
# without leading '/' is more clear that it is not an absolute path in the currently mounted tree of filesystems
# instead the subvolume path is relative to the toplevel/root subvolume of the particular btrfs filesystem
# (i.e. a subvolume path is an absolute path in the particular btrfs filesystem)
# see https://btrfs.wiki.kernel.org/index.php/Mount_options
test "/" != "$btrfs_subvolume_path" && btrfs_subvolume_path=${btrfs_subvolume_path#/}
if test -n "btrfs_subvolume_path" ; then
echo "btrfsnocopyonwrite $btrfs_subvolume_path"
else
echo "# $subvolume_mountpoint has the 'no copy on write' attribute set but $findmnt_command does not show its btrfs subvolume path"
fi
fi
done
else
echo "# Attributes cannot be determined because no executable 'lsattr' and/or 'findmnt' command(s) found."
fi
fi

) >> $DISKLAYOUT_FILE
Expand Down

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