[RFC V2] init: support device of major:minor:offset format

[Chen Yu]

Distribution like Ubuntu uses klibc rather than uswsusp to resume
system from hibernation, which will treat 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 restoring.
However in current implementation, 8:3:0 will be treated as an invalid
device format, and it is found that manual resumming from hibernation
will fail on lastest kernel.

This patch adds support for device with major:minor:offset format
when resumming from hibernation.

Reported-by: Prigent Christophe <christophe.prigent@xxxxxxxxx>
Reported-by: Martin Steigerwald <martin@xxxxxxxxxxxx>
Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
---
 init/do_mounts.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/init/do_mounts.c b/init/do_mounts.c
index 8369ffa..e2e3538 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -225,10 +225,12 @@ 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;
-- 
1.9.1

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