Re: git: 4a30d7bb373c - main - growfs script: add swap partition as well as growing root
Date: Sun, 11 Dec 2022 10:09:25 UTC
Hi Mike,
thanks for implementation. After the MFC and the new -STABLE snapshots
I am really looking forward to try this out an my RPi4B.
--Gordon
On Sat, Dec 10, 2022 at 07:41:13PM +0000, Mike Karels wrote:
> The branch main has been updated by karels:
>
> URL: https://cgit.FreeBSD.org/src/commit/?id=4a30d7bb373c08f42f953b9cd1e793e236b4cd92
>
> commit 4a30d7bb373c08f42f953b9cd1e793e236b4cd92
> Author: Mike Karels <karels@FreeBSD.org>
> AuthorDate: 2022-12-10 19:38:36 +0000
> Commit: Mike Karels <karels@FreeBSD.org>
> CommitDate: 2022-12-10 19:38:36 +0000
>
> growfs script: add swap partition as well as growing root
>
> Add the ability to create a swap partition in the course of growing
> the root file system on first boot, enabling by default. The default
> rules are: add swap if the disk is at least 15 GB (decimal), and the
> existing root is less than 40% of the disk. The default size is 10%
> of the disk, but is limited by the memory size. The limit is twice
> memory size up to 4 GB, 8 GB up to 8 GB memory, and memory size over
> 8 GB memory. Swap size is clamped at vm.swap_maxpages/2 as well.
> The new swap partition is labeled as "growfs_swap".
>
> The default behavior can be overridden by setting growfs_swap_size in
> /etc/rc.conf or in the kernel environment, with kenv taking priority.
> A value of 0 inhibits the addition of swap, an empty value specifies
> the default, and other values indicate a swap size in bytes.
>
> By default, addition of swap is inhibited if a swap partition is found
> in the output of the sysctl kern.geom.conftxt before the current root
> partition, usually meaning that there is another disk present.
> Swap space is not added if one is already present in /etc/fstab.
>
> The root partition is read-only when growfs runs, so /etc/fstab can
> not be modified. That step is handled by a new growfs_fstab script,
> added in a separate commit. Set the value "growfs_swap_pdev" in kenv
> to indicate that this should be done, as well as for internal use.
>
> There is optional verbose output meant for debugging; it can only be
> enabled by modifying the script (in two places, for sh and awk).
> This should be removed before release, after testing on -current.
>
> Discussed with: cperciva
> Reviewed by: imp (previous version)
> Differential Revision: https://reviews.freebsd.org/D37462
> ---
> libexec/rc/rc.d/growfs | 178 +++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 172 insertions(+), 6 deletions(-)
>
> diff --git a/libexec/rc/rc.d/growfs b/libexec/rc/rc.d/growfs
> index 5402bd442279..3c48a7dca6b2 100755
> --- a/libexec/rc/rc.d/growfs
> +++ b/libexec/rc/rc.d/growfs
> @@ -1,5 +1,6 @@
> #!/bin/sh
> #
> +# Copyright 2022 Michael J. Karels
> # Copyright 2014 John-Mark Gurney
> # All rights reserved.
> #
> @@ -32,8 +33,9 @@
> # BEFORE: root
> # KEYWORD: firstboot
>
> -# This allows us to distribute an image
> -# and have it work on essentially any size drive.
> +# Grow root partition to fill available space, optionally adding a swap
> +# partition at the end. This allows us to distribute an image and
> +# have it work on essentially any size drive.
>
> # Note that this uses awk(1), and thus will not work if /usr is on a separate
> # filesystem. We need to run early, because there might be not enough free
> @@ -48,7 +50,7 @@ start_cmd="growfs_start"
> stop_cmd=":"
> rcvar="growfs_enable"
>
> -growfs_get_diskdev ()
> +growfs_get_diskdev()
> {
> local _search=${1}
> sysctl -b kern.geom.conftxt |
> @@ -61,8 +63,51 @@ growfs_get_diskdev ()
> done
> }
>
> -growfs_start ()
> +# Compute upper bound on swap partition size (if added), based on physmem
> +# and vm.swap_maxpages / 2 (the limit that elicits a warning).
> +# Rule for swap size based on memory size:
> +# up to 4 GB twice memory size
> +# 4 GB - 8 GB 8 GB
> +# over 8 GB memory size
> +growfs_swap_max()
> {
> + memsize=$(sysctl -n hw.physmem)
> + memsizeMB=$(($memsize / (1024 * 1024)))
> +
> + if [ $memsizeMB -lt 4096 ]
> + then
> + swapmax=$(($memsize * 2))
> + elif [ $memsizeMB -lt 8192 ]
> + then
> + swapmax=$((8192 * 1024 * 1024))
> + else
> + swapmax=$memsize
> + fi
> +
> + pagesize=$(sysctl -n hw.pagesize)
> + vm_swap_max=$(($(sysctl -n vm.swap_maxpages) / 2 * $pagesize))
> +
> + if [ $swapmax -gt $vm_swap_max ]
> + then
> + $swapmax=$vm_swap_max
> + fi
> + echo -n "$swapmax"
> +}
> +
> +# Find newly-added swap partition on parent device ($1).
> +growfs_last_swap()
> +{
> + swapdev=$(gpart list $1 | awk '
> + $2 == "Name:" { dev = $3 }
> + $1 == "type:" && $2 == "freebsd-swap" { swapdev = dev }
> + END { print swapdev }
> + ')
> + echo -n $swapdev
> +}
> +
> +growfs_start()
> +{
> + verbose=0
> echo "Growing root partition to fill device"
> FSTYPE=$(mount -p | awk '{ if ( $2 == "/") { print $3 }}')
> FSDEV=$(mount -p | awk '{ if ( $2 == "/") { print $1 }}')
> @@ -100,19 +145,126 @@ growfs_start ()
> diskdev=${rootdev}
> fi
>
> + # Check kenv for growfs_swap_size; if not present,
> + # check $growfs_swap_size from /etc/rc.conf.
> + # A value of 0 suppresses swap addition,
> + # "" (or unset) specifies the default;
> + # other values indicate the size in bytes.
> + # If default, check whether swap is already in fstab;
> + # if so, don't add another.
> + addswap=1
> + swapsize="$(kenv -q growfs_swap_size 2>/dev/null)"
> + case "$swapsize" in
> + "0") addswap=0
> + ;;
> + "") case "$growfs_swap_size" in
> + "0") addswap=0
> + ;;
> + "")
> + if ! awk '
> + /^#/ { next }
> + $3 == "swap" { exit 1 }
> + ' < /etc/fstab
> + then
> + addswap=0
> + fi
> + ;;
> + *) swapsize="$growfs_swap_size"
> + ;;
> + esac
> + ;;
> + *) ;;
> + esac
> +
> + swaplim=$(growfs_swap_max)
> +
> + [ $verbose -eq 1 ] && {
> + echo "diskdev is $diskdev"
> + echo "search is $search"
> + echo "swapsize is $swapsize"
> + echo "swaplim is $swaplim"
> + }
> +
> sysctl -b kern.geom.conftxt | awk '
> {
> + verbose = 0
> lvl=$1
> device[lvl] = $3
> type[lvl] = $2
> idx[lvl] = $7
> + offset[lvl] = $9
> parttype[lvl] = $13
> + size[lvl] = $4
> + if (verbose) print lvl, type[lvl], $3
> + if (type[lvl] == "DISK") {
> + disksize = size[lvl]
> + if (verbose)
> + print "disksize ", disksize
> + # Don't add swap on disks under 15 GB (decimal) by default.
> + if (addswap == 1 && (size[lvl] > 15000000000 || swapsize > 0))
> + doing_swap = 1
> + else
> + doing_swap = 0
> + } else if (type[lvl] == "PART" && $11 == "freebsd-swap" && \
> + int(swapsize) == 0) {
> + # This finds swap only if it precedes root, e.g. preceding disk.
> + addswap = 0
> + doing_swap = 0
> + print "swap device exists, not adding swap"
> + }
> if (dev == $3) {
> for (i = 1; i <= lvl; i++) {
> # resize
> if (type[i] == "PART") {
> pdev = device[i - 1]
> - cmd[i] = "gpart resize -i " idx[i] " " pdev
> + if (verbose)
> + print i, pdev, addswap, disksize, \
> + doing_swap
> + swapcmd = ""
> + # Allow swap if current root is < 40% of disk.
> + if (parttype[i] != "MBR" && doing_swap == 1 && \
> + (size[i] / disksize < 0.4 || \
> + swapsize > 0)) {
> + print "Adding swap partition"
> + if (int(swapsize) == 0) {
> + swapsize = int(disksize / 10)
> + if (swapsize > swaplim)
> + swapsize = swaplim
> + }
> + sector = $5
> + swapsize /= sector
> + if (verbose)
> + print "swapsize sectors",
> + swapsize
> + align = 4 * 1024 * 1024 / sector
> +
> + # Estimate offset for swap; let
> + # gpart compute actual start and size.
> + # Assume expansion all goes into this
> + # partition for MBR case.
> + if (parttype[i - 1] == "MBR") {
> + if (verbose)
> + print "sz ", size[i - 1], \
> + " off ", offset[i - 1]
> + expand = size[0] - \
> + (size[i - 1] + offset[i - 1])
> + } else {
> + if (verbose)
> + print "sz ", size[i], \
> + " off ", offset[i]
> + expand = size[0] - \
> + (size[i] + offset[i])
> + }
> + if (verbose)
> + print "expand ", expand, \
> + " sz ", size[i]
> + swapbase = (expand + size[i]) / sector
> + swapbase -= swapsize + align
> + swapcmd = "gpart add -t freebsd-swap -a " align " -b " swapbase " " pdev "; kenv growfs_swap_pdev=" pdev " >/dev/null; "
> + if (verbose)
> + swapcmd = "set -x; " swapcmd
> + }
> + cmd[i] = swapcmd "gpart resize -i " idx[i] " " pdev
> if (parttype[i] == "GPT")
> cmd[i] = "gpart recover " pdev " ; " cmd[i]
> } else if (type[i] == "LABEL") {
> @@ -128,7 +280,7 @@ growfs_start ()
> }
> exit 0
> }
> -}' dev="$search"
> +}' dev="$search" addswap="$addswap" swapsize="$swapsize" swaplim="$swaplim"
> gpart commit "$diskdev" 2> /dev/null
> case "$FSTYPE" in
> ufs)
> @@ -138,6 +290,20 @@ growfs_start ()
> zpool online -e $pool $rootdev
> ;;
> esac
> +
> + # Get parent device of swap partition if one was added;
> + # if so, find swap device and label it.
> + pdev=$(kenv -q growfs_swap_pdev)
> + if [ -n "$pdev" ]
> + then
> + dev=$(growfs_last_swap "$pdev")
> + if [ -z "$dev" ]
> + then
> + echo "Swap partition not found on $pdev"
> + exit 0
> + fi
> + glabel label -v growfs_swap $dev
> + fi
> }
>
> load_rc_config $name
>
--