On Thu, Sep 10, 2015 at 07:44:02AM +0000, Atsushi Kumagai wrote:
> >Hello Kumagai,
> >
> >On Wed, Sep 09, 2015 at 07:51:50AM +0000, Atsushi Kumagai wrote:
> >> Hello Cliff,
> >>
> >> >From: Cliff Wickman <cpw at sgi.com>
> >> >
> >> >This patch enhances the --work-dir feature to make it easier to use.
> >> >
> >> >Kumagai, I plan to require the --work-dir for the -e feature, as you suggested. I did find --work-dir
> >> >hard to implement because of the differences between the way the various distros mount the root device
> >> >in the crashkernel. Hence this patch.
> >> >
> >> >Currently the --work-dir=<PATH> must be specified in a form that is valid in the crashkernel's environment.
> >> >In other words, the boot kernel's /var, for example, must be specified as:
> >> > RHEL6: /mnt/var/
> >> > RHEL7: /sysroot/var/
> >> > SLES11: /kdump/0/var/
> >> > SLES12: (with root=kdump) /kdump/mnt0/var/
> >> >And the administrator must remember to create that directory.
> >> >
> >> >If these conditions are not met makedumpfile fails, with little explanation as to why.
> >> >
> >> >This patch:
> >> >
> >> >- Allow the path to be one that is valid in the crashkernel's environment, or allow
> >> > it to be valid in the boot kernel's environment. In the second case, adjust the path to
> >> > how the root device is mounted in the crashkernel.
> >> > Limitation: The adjustment is only made if a dump file is being written, and the dump is
> >> > being written to /var/crash/. Otherwise you must (as currently) use a path that is known
> >> > to be valid in the crashkernel's environment.
> >> >
> >> >- Make the directory if it does not already exist. All components of the path are
> >> > made if necessary, similar to mkdir -p.
> >>
> >> I think such adjusting should be done in kdump feature side (e.g. kexec-tools) since
> >> it constructs the crash kernel's environment. Each distro's kdump feature can
> >> take care of each own environment.
> >
> >> Just checking by is_dir() and creating a directory are enough in makedumpfile side.
> >>
> >> Thanks,
> >> Atsushi Kumagai
> >
> >I have been looking at how this could be done.
> >As each distro may mount the root filesystem differently, it would seem to me that
> >the name must be passed to makedumpfile somehow. I don't see kexec having a role but
> >the scripts that make the kdump initrd could.
> >Am I missing your point in concluding that?
>
> Let's say about RHEL, if *path* parameter in kdump.conf is /var/crash,
> mkdumprd can pass it to --work-dir. Since that path can store vmcore,
> it must store also bitmaps and makedumpfilepfns.
>
> >One could add another option to makedumpfile (maybe --root=<path>). And then the distro's
> >scripts could add that option to the makedumpfile command line. But that turns out to be
> >difficult to do in SLES, as it has its own binary named 'kdumptool' that invokes
> >makedumpfile and it does not have a way to pass an option to makedumpfile
> >that is derived at mkdumprd time. It only passes along options that have been stored
> >in /etc/sysconfig/kdump.
> >
> >Deriving the root path from the dump name is not very reliable if it depends on a
> >convention that could change.
> >What is configured in the kdump or kdump.conf file is the "/var/crash" or similar dump
> >file directory.
> >I propose to add a --dump-dir option to makedumpfile. The distro script can easily
> >add --dump-dir=/var/crash to the command line, and then the path to root can be
> >accurately derived. If --dump-dir is not specified then --work-dir would have to
> >be pre-adjusted, as it is currently.
>
> Why don't you think --work-dir=/var/crash, it's simple.
In RHEL6 makedumpfile would have to adjust that to /mnt/var/crash.
In RHEL7, /sysroot/var/crash
Yes, passing it as --work-dir=/var/crash is sufficient, as long as
makedumpfile prepends everything in the dump file name before '/var/crash'
to the work-dir. And assuming we are always satisfied to use the dump
file directory as the work-dir (and that works for me).
So can we do that? i.e. take --work-dir to be a complete path in the
crashkernel environment. And if it does not exist, adjust it using
the path in the dump name?
-Cliff
>
>
> Thanks,
> Atsushi Kumagai
>
> >-Cliff
> >>
> >> >---
> >> > makedumpfile.c | 144 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >> > makedumpfile.h | 3 -
> >> > print_info.c | 15 ++++-
> >> > 3 files changed, 158 insertions(+), 4 deletions(-)
> >> >
> >> >Index: code/makedumpfile.c
> >> >===================================================================
> >> >--- code.orig/makedumpfile.c
> >> >+++ code/makedumpfile.c
> >> >@@ -25,6 +25,7 @@
> >> > #include <sys/time.h>
> >> > #include <limits.h>
> >> > #include <assert.h>
> >> >+#include <sys/stat.h>
> >> >
> >> > struct symbol_table symbol_table;
> >> > struct size_table size_table;
> >> >@@ -10364,6 +10365,146 @@ int show_mem_usage(void)
> >> > return TRUE;
> >> > }
> >> >
> >> >+/*
> >> >+ * return 1 if path is a directory
> >> >+ * else return 0
> >> >+ */
> >> >+int
> >> >+isdir(char *path)
> >> >+{
> >> >+ struct stat buf;
> >> >+
> >> >+ if (path) {
> >> >+ if (stat(path, &buf) || !S_ISDIR(buf.st_mode)) {
> >> >+ return 0;
> >> >+ }
> >> >+ return 1;
> >> >+ } else {
> >> >+ return 0;
> >> >+ }
> >> >+}
> >> >+
> >> >+/*
> >> >+ * Set info->root_dir to the crashkernel's path to the bootkernel's root
> >> >+ * or set it to null if that path cannot be determined.
> >> >+ * We must assume that the dump file is in the bootkernel's /var/crash/
> >> >+ */
> >> >+void
> >> >+set_rootdir()
> >> >+{
> >> >+ int len;
> >> >+ char *cp1, *cp2;
> >> >+
> >> >+ /* allow this function to be called multiple times */
> >> >+ if (info->root_dir)
> >> >+ return;
> >> >+
> >> >+ if (!info->name_dumpfile) {
> >> >+ info->root_dir = NULL;
> >> >+ return;
> >> >+ }
> >> >+
> >> >+ len = (int)strlen(info->name_dumpfile);
> >> >+ if (len == 0) {
> >> >+ info->root_dir = NULL;
> >> >+ return;
> >> >+ }
> >> >+ info->root_dir = malloc(len);
> >> >+ cp1 = info->name_dumpfile;
> >> >+ cp2 = cp1;
> >> >+ while (*cp2 != '\0') {
> >> >+ if (!strncmp(cp2, "/var/crash/", 11)) {
> >> >+ len = cp2 - cp1;
> >> >+ strncpy(info->root_dir, cp1, len);
> >> >+ if (!isdir(info->root_dir)) {
> >> >+ fprintf(stderr, "Error: root directory %s does not exist\n",
> >> >+ info->root_dir);
> >> >+ exit(1);
> >> >+ }
> >> >+ return;
> >> >+ }
> >> >+ cp2++;
> >> >+ }
> >> >+ info->root_dir = NULL;
> >> >+ return;
> >> >+}
> >> >+
> >> >+/*
> >> >+ * The --work-dir directory should be validated and created if necessary.
> >> >+ */
> >> >+void
> >> >+adjust_working_dir()
> >> >+{
> >> >+ int ret, finished=0;
> >> >+ char *hold, *inter_dir = NULL, *cp1, *cp2;
> >> >+
> >> >+ /* if a crashkernel root environment was specified, no adjust is necessary */
> >> >+ if (isdir(info->working_dir))
> >> >+ return;
> >> >+
> >> >+ set_rootdir();
> >> >+
> >> >+ if (!strncmp(info->working_dir, "/", 1)) {
> >> >+ /* an absolute path should either exist in the crashkernel's
> >> >+ root, or should be adjusted to be relative to it */
> >> >+ if (info->root_dir) {
> >> >+ hold = malloc(strlen(info->working_dir)+1);
> >> >+ strcpy(hold, info->working_dir);
> >> >+ info->working_dir = malloc(strlen(info->root_dir) + strlen(info->working_dir));
> >> >+ inter_dir = malloc(strlen(info->root_dir) + strlen(info->working_dir));
> >> >+ strcpy(info->working_dir, info->root_dir);
> >> >+ strcat(info->working_dir, hold);
> >> >+ free (hold);
> >> >+ fprintf(stderr, "--workdir set to %s\n", info->working_dir);
> >> >+ } else {
> >> >+ inter_dir = malloc(strlen(info->working_dir));
> >> >+ }
> >> >+ } else {
> >> >+ /* a relative path that does not already exist should be made absolute; it is taken to
> >> >+ be relative to the crash kernel's root */
> >> >+ if (info->root_dir) {
> >> >+ hold = malloc(strlen(info->working_dir)+1);
> >> >+ strcpy(hold, info->working_dir);
> >> >+ info->working_dir = malloc(strlen(info->root_dir) + strlen(info->working_dir) + 1);
> >> >+ inter_dir = malloc(strlen(info->root_dir) + strlen(info->working_dir) + 1);
> >> >+ strcpy(info->working_dir, info->root_dir);
> >> >+ strcat(info->working_dir, "/");
> >> >+ strcat(info->working_dir, hold);
> >> >+ free (hold);
> >> >+ fprintf(stderr, "--workdir set to %s\n", info->working_dir);
> >> >+ } else {
> >> >+ inter_dir = malloc(strlen(info->working_dir));
> >> >+ }
> >> >+ }
> >> >+
> >> >+ /* path is complete, now make sure it exists */
> >> >+ if (!isdir(info->working_dir)) {
> >> >+ strcpy(inter_dir, info->working_dir);
> >> >+ if (info->root_dir)
> >> >+ cp1 = inter_dir + strlen(info->root_dir) + 1;
> >> >+ else
> >> >+ cp1 = inter_dir + 1;
> >> >+ while (finished == 0) {
> >> >+ strcpy(inter_dir, info->working_dir);
> >> >+ cp2 = strchr(cp1, '/');
> >> >+ if (cp2) {
> >> >+ *cp2 = '\0';
> >> >+ cp1 = cp2 + 1;
> >> >+ } else {
> >> >+ finished = 1;
> >> >+ }
> >> >+ if (!isdir(inter_dir)) {
> >> >+ ret = mkdir(inter_dir, 0755);
> >> >+ if (ret) {
> >> >+ fprintf(stderr, "Error: mkdir(%s, 0755) returned %d\n",
> >> >+ inter_dir, ret);
> >> >+ exit(1);
> >> >+ }
> >> >+ }
> >> >+ }
> >> >+ }
> >> >+ return;
> >> >+}
> >> >
> >> > static struct option longopts[] = {
> >> > {"split", no_argument, NULL, OPT_SPLIT},
> >> >@@ -10549,6 +10690,9 @@ main(int argc, char *argv[])
> >> > return COMPLETED;
> >> > }
> >> >
> >> >+ if (info->working_dir)
> >> >+ adjust_working_dir();
> >> >+
> >> > if (elf_version(EV_CURRENT) == EV_NONE ) {
> >> > /*
> >> > * library out of date
> >> >Index: code/makedumpfile.h
> >> >===================================================================
> >> >--- code.orig/makedumpfile.h
> >> >+++ code/makedumpfile.h
> >> >@@ -1258,7 +1258,8 @@ struct DumpInfo {
> >> > /*
> >> > * for cyclic processing
> >> > */
> >> >- char *working_dir; /* working directory for bitmap */
> >> >+ char *working_dir; /* working directory for bitmap */
> >> >+ char *root_dir; /* crashkernel path to boot kernel's root */
> >> > mdf_pfn_t num_dumpable;
> >> > unsigned long bufsize_cyclic;
> >> > unsigned long pfn_cyclic;
> >> >Index: code/print_info.c
> >> >===================================================================
> >> >--- code.orig/print_info.c
> >> >+++ code/print_info.c
> >> >@@ -221,11 +221,20 @@ print_usage(void)
> >> > MSG(" size is at most N kilo bytes.\n");
> >> > MSG("\n");
> >> > MSG(" [--work-dir]:\n");
> >> >- MSG(" Specify the working directory for the temporary bitmap file.\n");
> >> >- MSG(" If this option isn't specified, the bitmap will be saved on memory.\n");
> >> >+ MSG(" Specify the working directory for temporary files such as the bitmap.\n");
> >> >+ MSG(" If this option isn't specified, the bitmap will be saved in memory.\n");
> >> > MSG(" Filtering processing has to do 2 pass scanning to fix the memory consumption,\n");
> >> >- MSG(" but it can be avoided by using working directory on file system.\n");
> >> >+ MSG(" but it can be avoided by using this working directory on the file system.\n");
> >> > MSG(" So if you specify this option, the filtering speed may be bit faster.\n");
> >> >+ MSG(" The directory path may be absolute or relative.\n");
> >> >+ MSG(" If relative, it is taken to be based at the root filesystem.\n");
> >> >+ MSG(" It may be an existing directory expressed with the path to the root filesystem as\n");
> >> >+ MSG(" it is mounted in the crashkernel.\n");
> >> >+ MSG(" Or it may expressed with '/' as the path to the root filesystem. In that case it will\n");
> >> >+ MSG(" be automatically adjusted to be relative to the root of the crashkernel.\n");
> >> >+ MSG(" The root of the crashkernel is determined from the dump name, if present. An assumption\n");
> >> >+ MSG(" is made that the dump file is to be written to /var/crash/.\n");
> >> >+ MSG(" If the directory does not exist it will be created, including multiple components.\n");
> >> > MSG("\n");
> >> > MSG(" [--non-mmap]:\n");
> >> > MSG(" Never use mmap(2) to read VMCORE even if it supports mmap(2).\n");
> >
> >--
> >Cliff Wickman
> >SGI
> >cpw at sgi.com
> >(651)683-7524 vnet 207524
> >(651)482-9347 home
> >
> >_______________________________________________
> >kexec mailing list
> >kexec at lists.infradead.org
> >http://lists.infradead.org/mailman/listinfo/kexec
--
Cliff Wickman
SGI
cpw at sgi.com
(651)683-7524 vnet 207524
(651)482-9347 home
