[Vivid][SRU][patch]init: fix regression by supporting devices with major:minor:offset format

[Zhang, Xiong Y]

The system will reboot after resuming from S4 on 15.04.
The following commit fixes this broken.

commit cb31ef485dd4c6a205d1064b42027f82076d00c8
Author: Chen Yu <yu.c.chen at intel.com>
Date:   Sun May 3 22:35:05 2015 +0800

    init: fix regression by supporting devices with major:minor:offset format

    Commit 283e7ad02 ("init: stricter checking of major:minor root=
    values") was so strict that it exposed the fact that a previously
    unknown device format was being used.

    Distributions like Ubuntu uses klibc (rather than uswsusp) to resume
    system from hibernation.  klibc expressed the swap partition/file in
    the form of major:minor:offset.  For example, 8:3:0 represents a swap
    partition in klibc, and klibc's resume process in initrd will finally
    echo 8:3:0 to /sys/power/resume for manually resuming.  However, due
    to commit 283e7ad02's stricter checking, 8:3:0 will be treated as an
    invalid device format, and manual resuming from hibernation will fail.

    Fix this by adding support for devices with major:minor:offset format
    when resuming from hibernation.

    Reported-by: Prigent, Christophe <christophe.prigent at intel.com>
    Signed-off-by: Chen Yu <yu.c.chen at intel.com>
    Acked-by: Rafael J. Wysocki <rjw at rjwysocki.net>
    Signed-off-by: Mike Snitzer <snitzer at redhat.com>

diff --git a/init/do_mounts.c b/init/do_mounts.c
index 8369ffa..a95bbdb 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -225,10 +225,11 @@ dev_t name_to_dev_t(const char *name)
 #endif

        if (strncmp(name, "/dev/", 5) != 0) {
-               unsigned maj, min;
+               unsigned maj, min, offset;
                char dummy;

-               if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2) {
+               if ((sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2) ||
+                   (sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3)) {
                        res = MKDEV(maj, min);
                        if (maj != MAJOR(res) || min != MINOR(res))
                                goto fail;
(END)

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