[OpenWrt-Devel] fstools: factory reset on power failure during startup

[John Crispin]

On 26/11/2015 09:24, Florian Eckert wrote:
> Hi,
> 
> I am using openwrt CC and an ubifs filesystem on top of ubi.
> If I plug off the power during startup, some times my configuration
> get lost and i am back to factory reset.
> 
> In the package fstools there is the bin "mount_root" it is called
> twice during startup.
> 1. S10boot at line 10
> 2. S95done at line 6
> 
> this calles edit the ./fs_state link
> 
> S10boot/S95done:
> ---
> Because ubifs is doing filesystem handling in a background process
> "ubi_bgt0d", could it be possible,
> that (see code) ./.fs_state is not rewritten written anymore?
> So that at next boot the system thinks he is in upgrade mode?
> 
> If I add a sleep(10) between unlink and symlink function call i can
> reproduce the failure if i unplug the power.
> I think the first think what should be done is to call
> "snprintf(valstr, sizeof(valstr), "%d", state);" before "unlink(path).
> 
> Or this this a deeper Problem?

interesting bug. felix recently added this "i crashed during firstboot,
lets retry" feature recently but it seesm that this works well on
classical (spi-)nor flash but fails on nand/ubi.

i've made a note and will look at this, however i am porting a new
target today so might not happen till start of the week. (unless felix
has time to look at it beforehand)

	John

> 
> int fs_state_set(const char *dir, enum fs_state state)
> {
>     char valstr[16];
>     char *path;
> 
> ->    path = alloca(strlen(dir) + 1 + sizeof("/.fs_state"));
> ->    sprintf(path, "%s/.fs_state", dir);
> ->    unlink(path);
> ->    snprintf(valstr, sizeof(valstr), "%d", state);
> 
>     return symlink(valstr, path);
> }
> 
> Regards
> Flo
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> 
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