FDS - missing swap page

Hi,

One of our devices is bricked due to the fds_init returning FDS_ERR_NO_PAGES. After flash analysis, I have discovered that all pages are marked as FDS_PAGE_DATA (no FDS_PAGE_SWAP). One of these pages is erased (just FDS_PAGE_TAG_MAGIC and FDS_PAGE_DATA header).

In our application, FDS is heavily used. During testing, we perform many power cycles. I do not have any clear reproduction path due to the fact that we found it just once (more than 200 devices online for a few months).

We are using SDK 14.2.0 with nRF52832 (custom board designs).

FDS flash dump can be found here: https://drive.google.com/drive/folders/1y_KOyIhVw9d-ZAAIc8SSa8k9vUOobDVz?usp=sharing

0 user12126 over 5 years ago in reply to user77348

I have also experienced this issue with SDK 17.0.2. On one device calls to fds_init during boot returned the NO_SWAP error. Looking at the memory contents all the FDS pages were tagged as DATA.
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0 user26071 over 5 years ago in reply to user12126

Is there a reliable way of reproducing this?

BR,

Edvin
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0 user99063 over 5 years ago in reply to user26071

I am having the same issue. I have not been able to reliably reproduce it, however, in my case at least one of the DATA pages is empty. This is a recoverable state as a blank data page can be erased and tagged as a SWAP page.

I suggest adding a new enum value of PAGE_DATA_EMPTY

enum
{
    PAGE_ERASED     = 0x1,  // One or more erased pages found.
    PAGE_DATA       = 0x2,  // One or more data pages found.
    PAGE_SWAP_CLEAN = 0x4,  // A clean (empty) swap page was found.
    PAGE_SWAP_DIRTY = 0x8,  // A dirty (non-empty) swap page was found.
    PAGE_DATA_EMPTY = 0x10, // One or more empty data pages found.
};

and a new enum to fds_init_opts_t

    // The filesystem only contains data pages, but at least one data page is empty.
    // It is likely that the device powered off during GC. It is safe to discard (erase)
    // a empty data page, since there is nothing stored there.    
    DISCARD_EMPTY_DATA             = (PAGE_DATA | PAGE_DATA_EMPTY),

Handling this in a similar manner as DISCARD_SWAP (erase empty data page then init that page as a swap), will produce the same result.