Re: [mdadm PATCH 11/12] mdmon: exec(2) when the switchroot argument is not "/"
From: Neil Brown <hidden>
Date: 2009-10-19 01:57:59
Hi Dan, thanks for all these. I have pulled them and pushed them out. However: On Tuesday October 13, dan.j.williams@intel.com wrote:
Try to execute mdmon from the target namespace. When used for initramfs handovers we need to drop all references to the initramfs filesystem for that memory to be freed.
I'm not 100% sure of this one.
Presumably an initramfs is mounted at '/', and the new root is mounted
at e.g. /newroot, and we are running:
mdmon md127 /newroot
and we want to drop all references to '/' that are held by mdmon.
Is that right?
This doesn't do that. The working directory and the root directory
are still '/' and the newly exec'ed mdmon isn't going to drop them.
Don't you want:
chdir(switchroot);
chroot(switchroot);
execl("/sbin/mdmon", "mdmon", devname, NULL);
and not bother with the sprintf??
NeilBrown
quoted hunk
Cc: Hans de Goede <redacted> Signed-off-by: Dan Williams <redacted> --- mdmon.c | 23 +++++++++++++++++++++++ 1 files changed, 23 insertions(+), 0 deletions(-)diff --git a/mdmon.c b/mdmon.c index 5f87e78..d3e8be5 100644 --- a/mdmon.c +++ b/mdmon.c@@ -369,6 +369,29 @@ int mdmon(char *devname, int devnum, int scan, char *switchroot) dprintf("starting mdmon for %s in %s\n", devname, switchroot ? : "/"); + + /* try to spawn mdmon instances from the target file system */ + if (switchroot && strcmp(switchroot, "/") != 0) { + char path[1024]; + pid_t pid; + + sprintf(path, "%s/sbin/mdmon", switchroot); + switch (fork()) { + case 0: + execl(path, "mdmon", devname, NULL); + exit(1); + case -1: + return 1; + default: + pid = wait(&status); + if (pid > -1 && WIFEXITED(status) && + WEXITSTATUS(status) == 0) + return 0; + else + return 1; + } + } + mdfd = open_dev(devnum); if (mdfd < 0) { fprintf(stderr, "mdmon: %s: %s\n", devname,