From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Wilck Subject: [PATCH v5 20/22] multipath -u: test if path is busy Date: Sat, 14 Apr 2018 00:00:13 +0200 Message-ID: <20180413220015.7032-21-mwilck@suse.com> References: <20180413220015.7032-1-mwilck@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180413220015.7032-1-mwilck@suse.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Christophe Varoqui , Benjamin Marzinski Cc: dm-devel@redhat.com, Martin Wilck List-Id: dm-devel.ids 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 --- multipath/main.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/multipath/main.c b/multipath/main.c index 573d94f9..c69e996e 100644 --- a/multipath/main.c +++ b/multipath/main.c @@ -675,6 +675,9 @@ 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, and the path is not in WWIDs * file, not currently multipathed, and has @@ -682,11 +685,45 @@ configure (struct config *conf, enum mpath_cmds cmd, * 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. + * + * The O_EXCL check is potentially dangerous, because it may + * race with other tasks trying to access the device. Therefore + * this code is only executed if the path hasn't been released + * to systemd earlier (see above). + * + * 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)); + /* + * Check if we raced with multipathd + */ + r = !sysfs_is_multipathed(VECTOR_SLOT(pathvec, 0)); + } goto print_valid; } -- 2.16.1