NeilBrown: mdmon: improve switchroot handling.
Martin F. Krafft
madduck at alioth.debian.org
Mon May 24 09:20:50 UTC 2010
Module: mdadm
Branch: upstream
Commit: e98ef2250905e8525bbdc0aab83e07a3de5a70ed
URL: http://git.debian.org/?p=pkg-mdadm/mdadm.git;a=commit;h=e98ef2250905e8525bbdc0aab83e07a3de5a70ed
Author: NeilBrown <neilb at suse.de>
Date: Fri Jan 29 12:14:17 2010 +1100
mdmon: improve switchroot handling.
The change to get mdmon to re-exec itself from the switchroot
filesystem broken switchroot in various ways. This fixes it.
If the switchroot path is not '/', mdmon will find the pid and
socket for the monitor, chroot to the new root, and exec mdmon
passing the pid in argv[2] and the socket in stdin.
If the switchroot path is actually a number, mdmon will not chroot,
but will kill that pid before taking over the array.
Signed-off-by: NeilBrown <neilb at suse.de>
---
mdmon.c | 61 +++++++++++++++++++++++++++++++++++++++++--------------------
1 files changed, 41 insertions(+), 20 deletions(-)
diff --git a/mdmon.c b/mdmon.c
index c66b06b..c5fcc4b 100644
--- a/mdmon.c
+++ b/mdmon.c
@@ -368,15 +368,35 @@ static int mdmon(char *devname, int devnum, int must_fork, char *switchroot)
dprintf("starting mdmon for %s in %s\n",
devname, switchroot ? : "/");
+ /* switchroot is either a path name starting with '/', or a
+ * pid of the original mdmon (we have already done the chroot).
+ * In the latter case, stdin is a socket connected to the original
+ * mdmon.
+ */
+
/* try to spawn mdmon instances from the target file system */
- if (switchroot && strcmp(switchroot, "/") != 0) {
- char path[1024];
+ if (switchroot && switchroot[0] == '/' &&
+ strcmp(switchroot, "/") != 0) {
pid_t pid;
+ char buf[20];
- sprintf(path, "%s/sbin/mdmon", switchroot);
switch (fork()) {
case 0:
- execl(path, "mdmon", devname, NULL);
+ victim = devname2mdmon(devname);
+ victim_sock = connect_monitor(devname);
+ if (chroot(switchroot) != 0) {
+ fprintf(stderr, "mdmon: failed to chroot to '%s': %s\n",
+ switchroot, strerror(errno));
+ exit(4);
+ }
+ ignore = chdir("/");
+ sprintf(buf, "%d", victim);
+ if (victim_sock) {
+ close(0);
+ dup(victim_sock);
+ close(victim_sock);
+ }
+ execl("/sbin/mdmon", "mdmon", devname, buf, NULL);
exit(1);
case -1:
return 1;
@@ -499,12 +519,12 @@ static int mdmon(char *devname, int devnum, int must_fork, char *switchroot)
/* we assume we assume that /sys /proc /dev are available in
* the new root
*/
- victim = devname2mdmon(container->devname);
- victim_sock = connect_monitor(container->devname);
- if (chroot(switchroot) != 0) {
- fprintf(stderr, "mdmon: failed to chroot to '%s': %s\n",
- switchroot, strerror(errno));
- exit(4);
+ if (switchroot[0] == '/') {
+ victim = devname2mdmon(container->devname);
+ victim_sock = connect_monitor(container->devname);
+ } else {
+ victim = atoi(switchroot);
+ victim_sock = 0;
}
}
@@ -532,16 +552,6 @@ static int mdmon(char *devname, int devnum, int must_fork, char *switchroot)
getppid());
close(pfd[1]);
- setsid();
- close(0);
- open("/dev/null", O_RDWR);
- close(1);
- ignore = dup(0);
-#ifndef DEBUG
- close(2);
- ignore = dup(0);
-#endif
-
mlockall(MCL_CURRENT | MCL_FUTURE);
if (clone_monitor(container) < 0) {
@@ -554,6 +564,17 @@ static int mdmon(char *devname, int devnum, int must_fork, char *switchroot)
try_kill_monitor(victim, container->devname, victim_sock);
close(victim_sock);
}
+
+ setsid();
+ close(0);
+ open("/dev/null", O_RDWR);
+ close(1);
+ ignore = dup(0);
+#ifndef DEBUG
+ close(2);
+ ignore = dup(0);
+#endif
+
do_manager(container);
exit(0);
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