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Seperate dracut and dracut-squash compressor for zstd

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Upstream: fedora
Resolves: bz2045949
Resolves: bz2044804
Conflict: none

commit fc1c79ffd2
Author: Tao Liu <ltao@redhat.com>
Date:   Sat Oct 8 12:09:08 2022 +0800

    Seperate dracut and dracut-squash compressor for zstd

    Previously kexec-tools will pass "--compress zstd" to dracut. It
    will make dracut to decide whether: a) call mksquashfs to make a
    zstd format squash-root.img, b) call cmd zstd to make a initramfs.

    Since dracut(>= 057) has decoupled the compressor for dracut and
    dracut-squash, So in this patch, we will pass the compressor seperately.

    Note:

    The is_squash_available && !dracut_has_option --squash-compressor
    && !is_zsdt_command_available case is left unprocessed on purpose.

    Actually, the situation when we want to call zstd compression is:
    1) If squash function OK, we want dracut to invoke mksquashfs to make
    a zstd format squash-root.img within initramfs.
    2) If squash function is not OK, and cmd zstd presents, we want dracut
    to invoke cmd zstd to make a zstd format initramfs.

    is_zstd_command_available check can handle case 2 completely.

    However, for the is_squash_available check, it cannot handle case 1
    completely. It only checks if the kernel supports squashfs, it doesn't
    check whether the squash module has been added by dracut when making
    initramfs. In fact, in kexec-tools we are unable to do the check,
    there are multiple ways to forbit dracut to load a module, such as
    "dracut -o module" and "omit_dracutmodules in dracut.conf".

    When squash dracut module is omitted, is_squash_available check will
    still pass, so "--compress zstd" will be appended to dracut cmdline,
    and it will call cmd zstd to do the compression. However cmd zstd may
    not exist, so it fails.

    The previous "--compress zstd" is ambiguous, after the intro of
    "--squash-compressor", "--squash-compressor" only effect for
    mksquashfs and "--compress" only effect for specific cmd.

    So for the is_squash_available && !dracut_has_option
    --squash-compressor && !is_zsdt_command_available case, we just leave
    it to be handled the default way.

    Reviewed-by: Philipp Rudo <prudo@redhat.com>
    Signed-off-by: Tao Liu <ltao@redhat.com>

Signed-off-by: Tao Liu <ltao@redhat.com>
This commit is contained in:
Tao Liu 2022-10-26 10:16:16 +08:00
parent 8b72bcfbab
commit b5a9e54629
4 changed files with 13 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
kdump-lib.sh
View File

@ -34,6 +34,12 @@ is_zstd_command_available()
[[ -x "$(command -v zstd)" ]]
}
dracut_have_option()
{
local _option=$1
! dracut "$_option" 2>&1 | grep -q "unrecognized option"
}
perror_exit()
{
derror "$@"
@ -448,8 +454,7 @@ is_wdt_active()
have_compression_in_dracut_args()
{
[[ "$(kdump_get_conf_val dracut_args)" =~ \
(^|[[:space:]])--(gzip|bzip2|lzma|xz|lzo|lz4|zstd|no-compress|compress)([[:space:]]|$) ]]
[[ "$(kdump_get_conf_val dracut_args)" =~ (^|[[:space:]])--(gzip|bzip2|lzma|xz|lzo|lz4|zstd|no-compress|compress|squash-compressor)([[:space:]]|$) ]]
}
# If "dracut_args" contains "--mount" information, use it

1
kexec-tools.spec
View File

@ -71,7 +71,6 @@ Requires: dracut >= 050
Requires: dracut-network >= 050
Requires: dracut-squash >= 050
Requires: ethtool
Recommends: zstd
Recommends: grubby
Recommends: hostname
BuildRequires: make

7
mkdumprd
View File

@ -432,10 +432,9 @@ done <<< "$(kdump_read_conf)"
handle_default_dump_target
if ! have_compression_in_dracut_args; then
# Here zstd is set as the default compression method. If squash module
# is available for dracut, libzstd will be used by mksquashfs. If
# squash module is unavailable, command zstd will be used instead.
if is_squash_available || is_zstd_command_available; then
if is_squash_available && dracut_have_option "--squash-compressor"; then
add_dracut_arg "--squash-compressor" "zstd"
elif is_zstd_command_available; then
add_dracut_arg "--compress" "zstd"
fi
fi

4
mkfadumprd
View File

@ -64,7 +64,9 @@ fi
# Same as setting zstd in mkdumprd
if ! have_compression_in_dracut_args; then
if is_squash_available || is_zstd_command_available; then
if is_squash_available && dracut_have_option "--squash-compressor"; then
_dracut_isolate_args+=(--squash-compressor zstd)
elif is_zstd_command_available; then
_dracut_isolate_args+=(--compress zstd)
fi
fi