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SubjectRe: [PATCH v6 12/15] ubi: fastmap: Add all fastmap pebs into 'ai->fastmap' when fm->used_blocks>=2
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Hi Richard,
> In ubi_wl_init() there is another corner case documented:
> /*
> * The fastmap update code might not find a free PEB for
> * writing the fastmap anchor to and then reuses the
> * current fastmap anchor PEB. When this PEB gets erased
> * and a power cut happens before it is written again we
> * must make sure that the fastmap attach code doesn't
> * find any outdated fastmap anchors, hence we erase the
> * outdated fastmap anchor PEBs synchronously here.
> */
> if (aeb->vol_id == UBI_FM_SB_VOLUME_ID)
> sync = true;
>
> So ubi_wl_init() makes sure that all old fastmap anchors get erased before UBI
> starts to operate. With your change this is no longer satisfied
I seem to understand the another case. But I'm still confused that why
outdated fastmap PEBs cannot be erased. When UBI comes to this point, it
means UBI is attached by **full scanning mode**, scan_fast() returns two
values:
UBI_NO_FASTMAP: scan all pebs from pnum UBI_FM_MAX_START, ai is
assigned with scan_ai, at last, all fastmap pebs are added into
'ai->fastmap'
UBI_BAD_FASTMAP: scan all pebs from pnum 0, all fastmap pebs are
added into 'ai->fastmap'

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