[OpenWrt-Devel] [PATCH v2 2/3] ext4_part_match: fix bug that prevented matching names

[Ram Chandra Jangir]

Hi Josua Mayer,

Partname is nothing but respective partition name of emmc card. It reads partition name from GPT partition table.
I think fdisk may not be able to write partition name in GPT table, but you should be able to create the partition name with GPT fdisk (consisting of the gdisk, cgdisk, sgdisk, and fixparts programs).

Thanks,
Ram 

-----Original Message-----
From: Josua Mayer [mailto:josua.mayer97 at gmail.com] 
Sent: Wednesday, May 04, 2016 6:13 PM
To: Ram Chandra Jangir <rjangi at codeaurora.org>; openwrt-devel at lists.openwrt.org
Subject: Re: [OpenWrt-Devel] [PATCH v2 2/3] ext4_part_match: fix bug that prevented matching names

Hi Ram,

Thanks for your comments. Now it appears I misunderstood what the code is supposed to match.
So if there is a PARTNAME= line, it can be matched.

However on my system I dont have PARTNAME.
Here a real-life sample:
root at OpenWrt:/# cat /sys/block/mmcblk0/mmcblk0p3/uevent
MAJOR=179
MINOR=3
DEVNAME=mmcblk0p3
DEVTYPE=partition
<end>
What is partname and how can I set it? fdisk? filesystem label?

br
Josua Mayer

Am 29.04.2016 um 14:35 schrieb Ram Chandra Jangir:
> Thanks  Josua Mayer.
> 
> Devname and partname both are different. Devname is holding the device node(ex.  mmcblkXpY) and given name(or partname) is the partition name(ex. rootfs or rootfs_data).
> For below uevent  sysfs entries, it tries to populate the device node(mmcblkXpY) in devname variable and tries to match the given name with the PARTNAME(buf will have this value("PARTNAME=rootfs_data") at  n'th iteration).
> If it is found then the loop will break, and we will get the given name's device node(/dev/mmcblkXpY) which will be mounted later.
> 
> Example:
> root at OpenWrt:/# cat /sys/block/mmcblk0/mmcblk0p3/uevent
> MAJOR=179
> MINOR=3
> DEVNAME=mmcblk0p3      <--  device node: /dev/mmcblk0p3
> DEVTYPE=partition
> PARTN=3
> PARTNAME=rootfs_data
> 
> This is required, because the emmc card may have multiple partitions too. So our aim is to get the device node from the given name's uevent file.
> 
> Thanks,
> Ram
> 
> -----Original Message-----
> From: openwrt-devel [mailto:openwrt-devel-bounces at lists.openwrt.org] 
> On Behalf Of josua.mayer97 at gmail.com
> Sent: Thursday, April 28, 2016 11:50 PM
> To: openwrt-devel at lists.openwrt.org
> Cc: Josua Mayer <privacy at not.given>
> Subject: [OpenWrt-Devel] [PATCH v2 2/3] ext4_part_match: fix bug that 
> prevented matching names
> 
> From: Josua Mayer <privacy at not.given>
> 
> Actually use the populated devname variable to compare against given name, instead of the buf variable, which incidentally contains either:
> MAJOR=xyz, MINOR=x, or DEVTYPE=partition, none of which ever match a name.
> 
> Signed-off-by: Josua Mayer <josua.mayer97 at gmail.com>
> ---
>  libfstools/ext4.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libfstools/ext4.c b/libfstools/ext4.c index 
> f648aa8..b9401c3 100644
> --- a/libfstools/ext4.c
> +++ b/libfstools/ext4.c
> @@ -78,7 +78,7 @@ ext4_part_match(char *dev, char *name, char *filename)
>  			continue;
>  		}
>  		/* Match partition name */
> -		if (strstr(buf, name))  {
> +		if (strstr(devname, name))  {
>  			ret = 0;
>  			break;
>  		}
> --
> 2.6.6
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