Re: ubi_wl_get_peb: Unable to get a free PEB from user WL pool

[Richard Weinberger <richard@nod.at>]

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Jörg,

Am 06.08.2015 um 00:17 schrieb Jörg Krause:
>>>> Then just disable it. :)
>>>
>>> I did :) I thought fastmap is used automatically by the UBI driver?
>>
>> It will *use* fastmap automatically but not convert non-fastmap UBI 
>> images
>> to fastmap.
>> You can enable ubi.fm_autoconvert to do so.
> 
> Sorry for asking, but how do I create an UBI image with fastmap
> support? I've never read something about this.

You have to use the ubi.fm_autoconvert parameter. The UBI will automatically
write down a fastmap if needed.

Currently it is not possible to create a fastmap-enabled UBI image
using ubinize.
The reason is that fastmap stores the LEB->PEB mappings to allow
a fast attach. ubinize cannot know which PEBs are bad.
So, we'd need a tool which creates the fastmap while flashing to the nand.

>>>> Meanwhile I'll find out what exactly is going on.
>>>
>>> Many thanks!
>>
>> Can you please apply the attached debug patch?
>> I wonder why exactly the auto resize function is failing.
> 
> autoresize: cannot auto-resize volume 0: -28

I have good and bad news.
The good news is that I know what is going on, the bad one
is that I don't have an good solution for it.

UBI is requesting a new PEB but your system is still busy with
erasing them. With fastmap disabled UBI can use produce_free_peb()
and wait for a new erased PEB.
But fastmap cannot use this helper as it releases ->wl_lock
and would lead to a inconsistent fastmap state.
Kernels < 4.1 did so and faced interesting fastmap corruptions.
I hoped using the current retry logic the issue you're facing cannot
happen. But as it seems I was wrong.

Can you please give the attached patch a try?

Thanks,
//richard

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diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c
index b2a6653..e47974d 100644
--- a/drivers/mtd/ubi/fastmap-wl.c
+++ b/drivers/mtd/ubi/fastmap-wl.c
@@ -206,12 +206,12 @@ again:
 
 	if (pool->used == pool->size) {
 		spin_unlock(&ubi->wl_lock);
-		if (retried) {
+		if (retried > 5) {
 			ubi_err(ubi, "Unable to get a free PEB from user WL pool");
 			ret = -ENOSPC;
 			goto out;
 		}
-		retried = 1;
+		retried++;
 		up_read(&ubi->fm_eba_sem);
 		goto again;
 	}