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. Suggested-by: Dave Young <dyoung(a)redhat.com&gt; Signed-off-by: Xunlei Pang <xlpang(a)redhat.com&gt; --- 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..6129602 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() +{ + return $(grep ^dracut_args /etc/kdump.conf | grep -q "\-\-mount") +} + +# 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) + [ $nr -gt 1 ] && { + echo "More than one mount targets specified in \"dracut_args\"." + return 1 + } + while read config_opt config_val; do # remove inline comments after the end of a directive. config_val=$(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 -- 1.8.3.1