# Btrfs filesystems with subvolumes need a special handling. # This script layout/prepare/GNU/Linux/136_include_btrfs_subvolumes_SLES_code.sh # contains the function btrfs_subvolumes_setup_SLES for SLES 12 (and later) special btrfs subvolumes setup. # The script layout/prepare/GNU/Linux/135_include_btrfs_subvolumes_generic_code.sh # contains the function btrfs_subvolumes_setup_generic for generic btrfs subvolumes setup (e.g. for Ubuntu 18.04). # All btrfs subvolume handling for SLES 12 (and later) special btrfs subvolumes setup # happens in the btrfs_subvolumes_setup_SLES function in this script. # For a plain btrfs filesystem without subvolumes the btrfs_subvolumes_setup_SLES function does nothing. btrfs_subvolumes_setup_SLES() { Log "Begin btrfs_subvolumes_setup_SLES( $@ )" # Local variables are visible only in this btrfs_subvolumes_setup_SLES function and its children: local dummy junk keyword info_message local device mountpoint mountopts target_system_mountpoint local subvolume_path subvolume_directory_path subvolume_mountpoint subvolume_mount_options local snapshot_subvolumes_devices_and_paths snapshot_subvolume_device_and_path snapshot_subvolume_device snapshot_subvolume_path local default_subvolume_path # Assign function arguments to meaningful variable names: # This function is called in 133_include_mount_filesystem_code.sh as follows: # btrfs_subvolumes_setup_SLES $device $mountpoint $mountopts # where $device is the device node where the filesystem was already created by 131_include_filesystem_code.sh # (usually a harddisk partition like e.g. /dev/sda1): device=$1 mountpoint=$2 # mountopts are of the form "-o foo,bar,baz" (see 133_include_mount_filesystem_code.sh) # which means $3 is '-o' and 'foo,bar,baz' is $4: mountopts="$3 $4" # Empty device or mountpoint may indicate an error. In this case be verbose and inform the user: if test -z "$device" -o -z "$mountpoint" ; then LogPrintError "Empty device='$device' or mountpoint='$mountpoint' may indicate an error, skipping btrfs_subvolumes_setup_SLES( $@ )." Log "Return 0 from btrfs_subvolumes_setup_SLES( $@ )" return 0 fi ########################################### # SLES 12 SP1 (and later) special btrfs subvolumes setup detection: SLES12SP1_btrfs_detection_string="@/.snapshots/" if grep -q "^btrfsdefaultsubvol $device $mountpoint [0-9]* $SLES12SP1_btrfs_detection_string" "$LAYOUT_FILE" ; then info_message="SLES12-SP1 (and later) btrfs subvolumes setup needed for $device (default subvolume path contains '$SLES12SP1_btrfs_detection_string')" LogPrint $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 230_filesystem_layout.sh # are deactivated (as '#btrfssnapshotsubvol ...') in the LAYOUT_FILE (disklayout.conf). # When there are active btrfs snapshot subvolumes entries, the user has manually # activated them (as 'btrfssnapshotsubvol ...') in the LAYOUT_FILE (disklayout.conf). # Because any btrfssnapshotsubvol entries are needed to exclude all btrfs snapshot subvolumes # 'grep "btrfssnapshotsubvol ..." ... | sed ...' is used. while read keyword dummy dummy dummy subvolume_path junk ; do if test -z "$subvolume_path" ; then continue fi # When there is a non-empty subvolume_path, btrfs snapshot subvolume handling is needed: Log "Handling snapshot subvolume $subvolume_path for $device at $mountpoint" # Remember btrfs snapshot subvolumes to exclude them when mounting all btrfs normal subvolumes below: snapshot_subvolumes_devices_and_paths="$snapshot_subvolumes_devices_and_paths $device,$subvolume_path" # Be verbose if there are active btrfs snapshot subvolumes entries (snapshot subvolumes cannot be recreated). # In this case inform the user that nothing can be done for activated snapshot subvolumes entries: if test "btrfssnapshotsubvol" = "$keyword" ; then info_message="It is not possible to recreate btrfs snapshot subvolumes, skipping $subvolume_path on $device at $mountpoint" LogPrint $info_message echo "# $info_message" >> "$LAYOUT_CODE" fi done < <( grep "btrfssnapshotsubvol $device $mountpoint " "$LAYOUT_FILE" | sed -e 's/.*#.*btrfssnapshotsubvol/#btrfssnapshotsubvol/' ) ########################################### # Btrfs normal subvolumes setup: # Create the normal btrfs subvolumes before the btrfs default subvolume setup # because currently the whole btrfs filesystem (i.e. its top-level/root subvolume) is mounted at the mountpoint # so that currently normal btrfs subvolumes can be created using the subvolume path relative to the btrfs toplevel/root subvolume # and that subvolume path relative to the btrfs toplevel/root subvolume is stored in the LAYOUT_FILE. # 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 # 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 LogPrintError "btrfsnormalsubvol entry with empty subvolume_path for $device at $mountpoint may indicate an error, skipping subvolume setup for it." continue fi # In case of SLES 12 SP1 (and later) special btrfs subvolumes setup skip setup of '@/.snapshots' normal btrfs subvolumes: if test "$SLES12SP1_btrfs_subvolumes_setup" ; then # In case of SLES 12 SP1 (and later) 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 "$subvolume_path" = "@/.snapshots" ; then info_message="No 'btrfs subvolume create' for '$subvolume_path' because it will be created by 'snapper/installation-helper --step 1' (which fails if that already exists)." LogPrint $info_message echo "# $info_message" >> "$LAYOUT_CODE" continue fi # Any normal btrfs subvolume under snapper's base subvolume is wrong # (see https://github.com/rear/rear/issues/944#issuecomment-238239926 # and https://github.com/rear/rear/issues/963 # and layout/save/GNU/Linux/230_filesystem_layout.sh). # Because any btrfs subvolume under '@/.snapshots/' lets "snapper/installation-helper --step 1" fail # any btrfs subvolume under '@/.snapshots/' is excluded here from being recreated # to not let "rear recover" fail because of such kind of wrong btrfs subvolumes # and inform the user about that via 'LogPrint': if [[ "$subvolume_path" == "@/.snapshots/"* ]] ; then info_message="Skipping subvolume setup for '$subvolume_path' because any btrfs subvolume under '.snapshots' would let 'snapper/installation-helper --step 1' fail." LogPrint $info_message echo "# $info_message" >> "$LAYOUT_CODE" continue fi fi # When there is a non-empty subvolume_path, btrfs normal subvolume setup is needed: Log "Setup normal subvolume $subvolume_path for $device at $mountpoint" # E.g. for 'btrfs subvolume create /foo/bar/subvol' the directory path /foo/bar/ must already exist # but 'subvol' must not exist because 'btrfs subvolume create' creates the subvolume 'subvol' itself. # When 'subvol' already exists (e.g. as normal directory), it fails with ERROR: '/foo/bar/subvol' exists. subvolume_directory_path=${subvolume_path%/*} if test "$subvolume_directory_path" = "$subvolume_path" ; then # When subvolume_path is only plain 'mysubvol' then also subvolume_directory_path becomes 'mysubvol' # but 'mysubvol' must not be made as a normal directory by 'mkdir' below: subvolume_directory_path="" fi target_system_mountpoint=$TARGET_FS_ROOT$mountpoint info_message="Creating normal btrfs subvolume $subvolume_path on $device at $mountpoint" Log $info_message ( echo "# $info_message" if test "$subvolume_directory_path" ; then # Test in the recovery system if the directory path already exists to avoid that # useless 'mkdir -p' commands are run which look confusing in the "rear recover" log # regardless that 'mkdir -p' does nothing when its argument already exists: echo "if ! test -d $target_system_mountpoint/$subvolume_directory_path ; then" echo " mkdir -p $target_system_mountpoint/$subvolume_directory_path" echo "fi" fi echo "btrfs subvolume create $target_system_mountpoint/$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 $target_system_mountpoint/$subvolume_path" ) >> "$LAYOUT_CODE" fi done < <( grep "^btrfsnormalsubvol $device $mountpoint " "$LAYOUT_FILE" ) ########################################### # Btrfs default subvolume setup: # 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'): for dummy in "once" ; do # Empty subvolume_path may indicate an error. In this case be verbose and inform the user: if test -z "$subvolume_path" ; then LogPrintError "btrfsdefaultsubvol entry with empty subvolume_path for $device at $mountpoint may indicate an error, skipping default subvolume setup for it." continue fi # When there is a non-empty subvolume_path, btrfs default subvolume setup is needed: Log "Setup default subvolume $subvolume_path for $device at $mountpoint" # Remember the btrfs default subvolume on that specific device which is needed when mounting all btrfs normal subvolumes below # (also needed when the default subvolume path is "/" to avoid that it gets remounted when mounting normal subvolumes below): default_subvolume_path="$subvolume_path" # When subvolume_path is "/", the default for the btrfs default subvolume is used # (i.e. the btrfs default subvolume is the toplevel/root subvolume): if test "/" = "$subvolume_path" ; then info_message="No special btrfs default subvolume is used on $device at $mountpoint, no default subvolume setup needed" Log $info_message echo "# $info_message" >> "$LAYOUT_CODE" continue fi # 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: target_system_mountpoint=$TARGET_FS_ROOT$mountpoint Log "Setting $subvolume_path as btrfs default subvolume for $device at $mountpoint" if test "$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 $target_system_mountpoint | sed -e 's/\///' | 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 $target_system_mountpoint" echo "# Begin step 1 of special SLES 12 SP1 btrfs default snapper snapshot subvolume setup" echo "umount $target_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 LogPrint 'Running snapper/installation-helper'" echo " $SLES12SP1_installation_helper_executable --step 1 --device $device --description 'first root filesystem'" echo "else LogPrintError '$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 $target_system_mountpoint" echo "# End step 1 of special SLES 12 SP1 btrfs default snapper snapshot subvolume setup" ) >> "$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 $target_system_mountpoint | sed -e 's/\///' | 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 $target_system_mountpoint" ) >> "$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 # which would result a wrong recovery because currently such an awkward setup is not supported. # Under the above assumption the btrfs filesystem needs to be umonted and mounted again so that # the special default subvolume gets mounted in the recovery system at $TARGET_FS_ROOT$mountpoint. Log "Remounting the btrfs default subvolume $subvolume_path for $device at $mountpoint" ( echo "# Remounting the $subvolume_path default subvolume at $target_system_mountpoint" echo "umount $target_system_mountpoint" echo "mount -t btrfs $mountopts $device $target_system_mountpoint" echo "# End btrfs default subvolume setup on $device at $mountpoint" ) >> "$LAYOUT_CODE" done ########################################### # Mounting all btrfs normal subvolumes: # After the btrfs default subvolume setup now the btrfs default subvolume is mounted and then it is possible # to mount the other btrfs normal subvolumes at their mountpoints in the tree of the mounted filesystems: while read dummy dummy subvolume_mountpoint subvolume_mount_options subvolume_path junk ; do # Empty subvolume_mountpoint or subvolume_mount_options or subvolume_path may indicate an error. # E.g. missing subvolume mount options result that the subvolume path is read into subvolume_mount_options and subvolume_path becomes empty. # Therefore be verbose and inform the user: if test -z "$subvolume_mountpoint" -o -z "$subvolume_mount_options" -o -z "$subvolume_path" ; then LogPrintError "btrfsmountedsubvol entry for $device where subvolume_mountpoint='$subvolume_mountpoint' or subvolume_mount_options='$subvolume_mount_options' or subvolume_path='$subvolume_path' is empty may indicate an error, skipping mounting it." continue 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 $snapshot_subvolume_device_and_path is "/dev/sdX99,my/subvolume,path" then split # at the first comma because device nodes (e.g. /dev/sdX99) do not contain a comma # but a subvolume path may contain a comma (e.g. my/subvolume,path). # If a subvolume path contains space or tab characters it will break here # because space tab and newline are standard bash internal field separators ($IFS) # so that admins who use such characters for their subvolume paths get hereby # an exercise in using fail-safe names and/or how to enhance standard bash scripts: snapshot_subvolume_device=${snapshot_subvolume_device_and_path%%,*} snapshot_subvolume_path=${snapshot_subvolume_device_and_path#*,} if test "$device" = "$snapshot_subvolume_device" -a "$subvolume_path" = "$snapshot_subvolume_path" ; then info_message="It is not possible to recreate btrfs snapshot subvolumes, skipping mounting $subvolume_path on $device at $subvolume_mountpoint" Log $info_message echo "# $info_message" >> "$LAYOUT_CODE" # If one snapshot_subvolume_device_and_path matches, # continue with the next btrfsmountedsubvol line from the LAYOUT_FILE # (i.e. continue with the while loop which is the 2th enclosing loop): continue 2 fi done target_system_mountpoint=$TARGET_FS_ROOT$subvolume_mountpoint # Remounting is needed when at the '/' mountpoint not the btrfs default subvolume is mounted: # On Fedora 21 what is mounted at the root of the filesystem tree (i.e. at the '/' mountpoint) # is not the btrfs default subvolume (the default subvolume is the toplevel/root subvolume). # 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 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 # on openSUSE 13.2 at '/' the default subvolume which is the root subvolume (ID 5 '/') is mounted: # btrfsdefaultsubvol /dev/sda2 / 5 / # btrfsmountedsubvol /dev/sda2 / rw,relatime,space_cache / # 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 # FIXME: Currently only for the mountpoint '/' there is this special handling. # In general the subvolume_mountpoint could be anything. # For example for a second disk /dev/sdb1 the disklayout.conf file could contain those entries: # btrfsdefaultsubvol /dev/sdb1 /data 5 / # btrfsmountedsubvol /dev/sdb1 /data rw,relatime,seclabel,space_cache datasubvol # This would mean for /dev/sdb1 what is mounted at its mountpoint /data # is not its btrfs default subvolume but the btrfs subvolume "datasubvol". # Currently such a setup is not supported for mountpoints other than '/'. if test '/' = "$subvolume_mountpoint" ; then # No remounting needed when the subvolume_path is the default_subvolume_path for this device # because then the default subvolume is already mounted by the "Btrfs default subvolume setup" above: if test "$subvolume_path" = "$default_subvolume_path" ; then Log "On $device btrfs default subvolume $default_subvolume_path already mounted at $subvolume_mountpoint, no remounting needed" continue fi # Remounting is needed when the subvolume_path is not the default_subvolume_path for this device: Log "On $device btrfs subvolume $subvolume_path currently not mounted at $subvolume_mountpoint, needs remounting" ( echo "# Begin remounting btrfs subvolume $subvolume_path at $target_system_mountpoint" echo "# On $device btrfs subvolume $subvolume_path is currently not mounted at $target_system_mountpoint, needs remounting:" echo "# Get the ID of the $subvolume_path subvolume because it must be mounted with subvolid=ID" echo "# (using subvol=NAME may not work as long as it is falsely mounted so that subvolume names may not match)" echo "subvolumeID=\$( btrfs subvolume list -a $target_system_mountpoint | sed -e 's/\///' | grep ' $subvolume_path\$' | tr -s '[:blank:]' ' ' | cut -d ' ' -f 2 )" echo "if test \"\$subvolumeID\" ; then" echo " # No remounting when subvolumeID is empty because then umount would work but mount would fail" echo " # Remounting the $subvolume_path subvolume at $target_system_mountpoint" echo " umount $target_system_mountpoint" echo " mount -t btrfs -o $subvolume_mount_options -o subvolid=\$subvolumeID $device $target_system_mountpoint" echo "else" echo " # Empty subvolumeID may indicate an error. Therefore be verbose and inform the user:" echo " LogPrintError 'Empty subvolumeID for $subvolume_path on $device may indicate an error, skipping remounting it to $subvolume_mountpoint'" echo "fi" echo "# End remounting btrfs subvolume $subvolume_path at $target_system_mountpoint" ) >> "$LAYOUT_CODE" # Handling of the '/' mountpoint is done hereby: continue fi # Do not mount when something is already mounted at the mountpoint. # In particular do not mount again the already mounted btrfs default subvolume or toplevel/root subvolume at the same mountpoint. # One same subvolume can be mounted at several mountpoints but one mountpoint cannot be used several times. Log "Mounting btrfs normal subvolume $subvolume_path on $device at $subvolume_mountpoint (if not something is already mounted there)." ( echo "# Mounting btrfs normal subvolume $subvolume_path on $device at $target_system_mountpoint (if not something is already mounted there):" # If target_system_mountpoint has a trailing '/' it must be cut, otherwise it is not found as an already mounted mountpoint. # In particular a subvolume_mountpoint '/' leads to a trailing '/' in target_system_mountpoint (e.g. '/mnt/local/') # and at least the recovery filesystem root $TARGET_FS_ROOT (by default '/mnt/local') is already mounted in any case here: echo "if ! mount -t btrfs | tr -s '[:blank:]' ' ' | grep -q ' on ${target_system_mountpoint%/} ' ; then" # Test in the recovery system if the target_system_mountpoint directory already exists to avoid that # useless 'mkdir -p' commands are run which look confusing in the "rear recover" log # regardless that 'mkdir -p' does nothing when its argument already exists: echo " if ! test -d $target_system_mountpoint ; then" echo " mkdir -p $target_system_mountpoint" echo " fi" echo " mount -t btrfs -o $subvolume_mount_options -o subvol=$subvolume_path $device $target_system_mountpoint" echo "fi" ) >> "$LAYOUT_CODE" done < <( grep "^btrfsmountedsubvol $device " "$LAYOUT_FILE" ) ########################################### # Return successfully: Log "End btrfs_subvolumes_setup_SLES( $@ )" true }