[dm-devel] [PATCH v3 17/20] multipath -u: test if path is busy
Martin Wilck
mwilck at suse.com
Mon Apr 2 19:50:48 UTC 2018
For "find_multipaths smart", check if a path is already in use
before setting DM_MULTIPATH_DEVICE_PATH to 1 or 2 (and thus,
SYSTEMD_READY=0). If we don't do this, a device which has already been
mounted (e.g. during initrd processing) may be unmounted by systemd, causing
havoc to the boot process.
Signed-off-by: Martin Wilck <mwilck at suse.com>
---
multipath/main.c | 31 ++++++++++++++++++++++++++++++-
1 file changed, 30 insertions(+), 1 deletion(-)
diff --git a/multipath/main.c b/multipath/main.c
index d09f117..392d5f0 100644
--- a/multipath/main.c
+++ b/multipath/main.c
@@ -629,16 +629,45 @@ configure (struct config *conf, enum mpath_cmds cmd,
if (cmd == CMD_VALID_PATH) {
+ struct path *pp;
+ int fd;
+
/* This only happens if find_multipaths and
* ignore_wwids is set.
* If there is currently a multipath device matching
* the refwwid, or there is more than one path matching
* the refwwid, then the path is valid */
- if (VECTOR_SIZE(curmp) != 0 || VECTOR_SIZE(pathvec) > 1)
+ if (VECTOR_SIZE(curmp) != 0) {
+ r = 0;
+ goto print_valid;
+ } else if (VECTOR_SIZE(pathvec) > 1)
r = 0;
else
/* Use r=2 as an indication for "maybe" */
r = 2;
+
+ /*
+ * If opening the path with O_EXCL fails, the path
+ * is in use (e.g. mounted during initramfs processing).
+ * We know that it's not used by dm-multipath.
+ * We may not set SYSTEMD_READY=0 on such devices, it
+ * might cause systemd to umount the device.
+ * Use O_RDONLY, because udevd would trigger another
+ * uevent for close-after-write.
+ *
+ * get_refwwid() above stores the path we examine in slot 0.
+ */
+ pp = VECTOR_SLOT(pathvec, 0);
+ fd = open(udev_device_get_devnode(pp->udev),
+ O_RDONLY|O_EXCL);
+ if (fd >= 0)
+ close(fd);
+ else {
+ condlog(3, "%s: path %s is in use: %s",
+ __func__, pp->dev,
+ strerror(errno));
+ r = 1;
+ }
goto print_valid;
}
--
2.16.1
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