There are some complaints about nfs kdump that users must mount nfs beforehand, which may cause some overhead to nfs server. For example, there're thounsands of diskless clients deployed with nfs dumping, each time the client is boot up, it will trigger kdump rebuilding so will mount nfs, thus resulting in thousands of nfs request concurrently imposed on the same nfs server.

We introduce a new way of specifying mount information via the already-existent "dracut_args" directive(so avoid adding extra directives in /etc/kdump.conf), we will skip all the filesystem mounting and checking stuff for it. So it can be used in the above-mentioned nfs scenario to avoid severe nfs server overhead.

Specifically, if there is any "--mount" information specified via "dracut_args" in /etc/kdump.conf, always use it as the final mount without any validation(mounting or checking like mount options, fs size, etc), so users are expected to ensure its correctness.

NOTE: -Only one mount target is allowed using "dracut_args" globally. -Dracut will create <mountpoint> if it doesn't exist in kdump kernel, <mountpoint> must be specified as an absolute path. -Users should do a test first and ensure it works because kdump does not prepare the mount or check all the validity.

Reviewed-by: Pratyush Anand panand@redhat.com Suggested-by: Dave Young dyoung@redhat.com Acked-by: Dave Young dyoung@redhat.com Signed-off-by: Xunlei Pang xlpang@redhat.com --- dracut-kdump.sh | 4 ++++ dracut-module-setup.sh | 5 +++++ kdump-lib.sh | 26 ++++++++++++++++++++++++-- kdumpctl | 13 ++++++++++++- 4 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/dracut-kdump.sh b/dracut-kdump.sh index 4aab205..42ba37f 100755 --- a/dracut-kdump.sh +++ b/dracut-kdump.sh @@ -146,6 +146,10 @@ read_kdump_conf() # remove inline comments after the end of a directive. config_val=$(strip_comments $config_val) case "$config_opt" in + dracut_args) + config_val=$(get_dracut_args_target "$config_val") + [[ -n "$config_val" ]] && add_dump_code "dump_fs $config_val" + ;; ext[234]|xfs|btrfs|minix|nfs) add_dump_code "dump_fs $config_val" ;; diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh index f5c0218..68e0ff8 100755 --- a/dracut-module-setup.sh +++ b/dracut-module-setup.sh @@ -450,6 +450,11 @@ kdump_install_conf() { ssh|nfs) kdump_install_net "$config_val" ;; + dracut_args) + if [[ $(get_dracut_args_fstype "$config_val") = nfs* ]] ; then + kdump_install_net "$(get_dracut_args_target "$config_val")" + fi + ;; kdump_pre|kdump_post|extra_bins) dracut_install $config_val ;; diff --git a/kdump-lib.sh b/kdump-lib.sh index 4567a05..e594496 100755 --- a/kdump-lib.sh +++ b/kdump-lib.sh @@ -23,7 +23,8 @@ is_ssh_dump_target()

is_nfs_dump_target() { - grep -q "^nfs" /etc/kdump.conf + grep -q "^nfs" /etc/kdump.conf || \ + [[ $(get_dracut_args_fstype "$(grep "^dracut_args .*--mount" /etc/kdump.conf)") = nfs* ]] }

is_raw_dump_target() @@ -45,7 +46,8 @@ is_fs_dump_target()

is_user_configured_dump_target() { - return $(is_ssh_dump_target || is_nfs_dump_target || is_raw_dump_target || is_fs_dump_target) + return $(is_mount_in_dracut_args || is_ssh_dump_target || is_nfs_dump_target || \ + is_raw_dump_target || is_fs_dump_target) }

strip_comments() @@ -406,3 +408,23 @@ is_wdt_mod_omitted() {

return $ret } + +# If "dracut_args" contains "--mount" information, use it +# directly without any check(users are expected to ensure +# its correctness). +is_mount_in_dracut_args() +{ + grep -q "^dracut_args .*--mount" /etc/kdump.conf +} + +# If $1 contains dracut_args "--mount", return <filesystem type> +get_dracut_args_fstype() +{ + echo $1 | grep "--mount" | sed "s/.*--mount .(.*)/\1/" | cut -d' ' -f3 +} + +# If $1 contains dracut_args "--mount", return <device> +get_dracut_args_target() +{ + echo $1 | grep "--mount" | sed "s/.*--mount .(.*)/\1/" | cut -d' ' -f1 +} diff --git a/kdumpctl b/kdumpctl index 0436bfc..4d83e69 100755 --- a/kdumpctl +++ b/kdumpctl @@ -236,12 +236,18 @@ check_config() { local nr

- nr=$(awk 'BEGIN{cnt=0} /^raw|^ssh[[:blank:]]|^nfs|^ext[234]|^xfs|^btrfs|^minix/{cnt++} END{print cnt}' $KDUMP_CONFIG_FILE) + nr=$(awk 'BEGIN{cnt=0} /^raw|^ssh[[:blank:]]|^nfs|^ext[234]|^xfs|^btrfs|^minix|^dracut_args .*--mount/{cnt++} END{print cnt}' $KDUMP_CONFIG_FILE) [ $nr -gt 1 ] && { echo "More than one dump targets specified." return 1 }

+ nr=$(grep "^dracut_args .*--mount" $KDUMP_CONFIG_FILE | grep -o "--mount" | wc -l) + [ $nr -gt 1 ] && { + echo "Multiple mount targets specified in one "dracut_args"." + return 1 + } + while read config_opt config_val; do # remove inline comments after the end of a directive. config_val=$(strip_comments $config_val) @@ -365,6 +371,11 @@ check_dump_fs_modified() local _new_dev _new_mntpoint _new_fstype local _target _path _dracut_args

+ # No need to check in case of mount target specified via "dracut_args". + if is_mount_in_dracut_args; then + return 0 + fi + # No need to check in case of raw target. # Currently we do not check also if ssh/nfs target is specified if is_ssh_dump_target || is_nfs_dump_target || is_raw_dump_target; then

Fedora dracut-network version >= 044-117 must be installed to work with this set of kexec-tools patches. Therefore adding dependency for them.

Acked-by: Dave Young dyoung@redhat.com Signed-off-by: Xunlei Pang xlpang@redhat.com --- kexec-tools.spec | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kexec-tools.spec b/kexec-tools.spec index d70b561..d386af1 100644 --- a/kexec-tools.spec +++ b/kexec-tools.spec @@ -45,8 +45,9 @@ Requires(post): systemd-units Requires(preun): systemd-units Requires(postun): systemd-units Requires(pre): coreutils sed zlib -Requires: dracut >= 044-75 -Requires: dracut-network, ethtool +Requires: dracut >= 044-117 +Requires: dracut-network >= 044-117 +Requires: ethtool BuildRequires: zlib-devel zlib zlib-static elfutils-devel-static glib2-devel bzip2-devel ncurses-devel bison flex lzo-devel snappy-devel BuildRequires: pkgconfig intltool gettext BuildRequires: systemd-units