Merge lp:~serge-hallyn/ubuntu/lucid/initramfs-tools/udevsettle into lp:ubuntu/lucid/initramfs-tools

[Serge Hallyn]

[Serge Hallyn (serge-hallyn)]

Sorry - changelog snafu. This merge should be against Natty of course,
and SRU'd back to maverick, lucid, and karmic, at least.

[lp:~serge-hallyn/ubuntu/lucid/initramfs-tools/udevsettle]

195. By Serge Hallyn on 2010-12-08

fix target release in changelog

[Evan Broder (broder)]

How exactly does multipath interact with devices that have already been mounted?

If I manage to mount /dev/disk/by-uuid/whatever *before* the multipath udev rule triggers, does that mean that the non-coalesced device stays mounted, or can multipath magically swap the devices out?

If it's the former, then it seems like there's still a problem if mountroot() outright wins the race against the udev rule. It seems like the better solution would be to add a local-premount script to multipath-tools-boot that does a udevadm settle, although it's worth noting that that will potentially impact boot time.

If it's the latter, then I'm not sure I understand the point of the multipath-tools-boot package.

review: Needs Information

[Serge Hallyn (serge-hallyn)]

That sounds like a good alternative, though if the race
you're worried about is real (I'm not certain if anything
prevents it, though I"ve never seen it) then I don't think
it would prevent it by itself.

I like the alternative for keeping the multipath fixes
closer to multipath itself. Thanks for the suggestion.

[Serge Hallyn (serge-hallyn)]

@Evan:

I don't want to 'delete' this proposal because that will
delete the comments. But there is no 'withdraw' option.
Could you hit 'reject' to close this please?

(I have the proposed alternate patch to multipath-tools,
and am proposing it to debian for starters)

thanks,
-serge

Unmerged revisions

195. By Serge Hallyn on 2010-12-08

fix target release in changelog

194. By Serge Hallyn on 2010-12-08

Clean up changelog for merge, and add a new non-private bug
that this closes.

193. By Serge Hallyn on 2010-12-08

version bump for maverick ppa.

192. By Serge Hallyn on 2010-11-20

bump ubuntu version

191. By Serge Hallyn on 2010-11-20

oops, it's udevadm settle, not udevsettle

190. By Serge Hallyn on 2010-11-19

fix version number

189. By Serge Hallyn on 2010-11-19

When using multipath, it is possible that mountroot() will race
with udev's renaming of /dev/disk/by-uuid/{rootfs-uuid} from
/dev/sd?? to /dev/mapper/something. After multipath has grabbed
the /dev/sd?? and until udev completes the rename, mounting
/dev/disk/by-uuid/{rootfs-uuid} will fail with -EBUSY. In that
case, call 'udevsettle' to wait until udev has finished all its
related actions.

(I wonder whether we should only do udevsettle if we got
-EBUSY, and fail as usual otherwise)

=== modified file 'debian/changelog'
--- debian/changelog	2010-04-26 15:17:47 +0000
+++ debian/changelog	2010-12-08 21:47:46 +0000
@@ -1,3 +1,15 @@
+initramfs-tools (0.92bubuntu79) natty; urgency=low
+
+  * When using multipath, it is possible that mountroot() will race
+    with udev's renaming of /dev/disk/by-uuid/{rootfs-uuid} from
+    /dev/sd?? to /dev/mapper/something.  After multipath has grabbed
+    the /dev/sd?? and until udev completes the rename, mounting
+    /dev/disk/by-uuid/{rootfs-uuid} will fail with -EBUSY.  In that
+    case, call 'udevsettle' to wait until udev has finished all its
+    related actions. (Closes LP: #686832)
+
+ -- Serge Hallyn <[e-mail]>  Fri, 19 Nov 2010 12:19:43 -0600
+
 initramfs-tools (0.92bubuntu78) lucid; urgency=low
 
   * hooks/compcache: Escape $-expansions inside <<EOF (thanks, Eugene San;

=== modified file 'scripts/local'
--- scripts/local	2009-12-21 23:06:53 +0000
+++ scripts/local	2010-12-08 21:47:46 +0000
@@ -69,10 +69,19 @@
 	# FIXME This has no error checking
 	[ -n "${FSTYPE}" ] && modprobe ${FSTYPE}
 
-	# FIXME This has no error checking
 	# Mount root
-	mount ${roflag} ${FSTYPE:+-t ${FSTYPE} }${ROOTFLAGS} ${ROOT} ${rootmnt}
-	mountroot_status="$?"
+	tries=0
+	ret=1
+	while [ $tries -lt 2 -a $ret -ne 0 ]; do
+		mount ${roflag} ${FSTYPE:+-t ${FSTYPE} }${ROOTFLAGS} ${ROOT} ${rootmnt}
+		ret=$?
+		if [ $ret -ne 0 ]; then
+			echo "failed attempt $tries to mount $ROOT as root"
+			udevadm settle
+			tries=$((tries+1))
+		fi
+	done
+	mountroot_status=$ret
 	if [ "$LOOP" ]; then
 		if [ "$mountroot_status" != 0 ]; then
 			if [ ${FSTYPE} = ntfs ] || [ ${FSTYPE} = vfat ]; then