Messages in this thread | | | Date | Tue, 11 Jan 2022 12:57:05 +0100 (CET) | From | Richard Weinberger <> | Subject | Re: [PATCH v6 12/15] ubi: fastmap: Add all fastmap pebs into 'ai->fastmap' when fm->used_blocks>=2 |
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----- Ursprüngliche Mail ----- > Von: "chengzhihao1" <chengzhihao1@huawei.com> > An: "richard" <richard@nod.at> > CC: "Miquel Raynal" <miquel.raynal@bootlin.com>, "Vignesh Raghavendra" <vigneshr@ti.com>, "mcoquelin stm32" > <mcoquelin.stm32@gmail.com>, "kirill shutemov" <kirill.shutemov@linux.intel.com>, "Sascha Hauer" > <s.hauer@pengutronix.de>, "linux-mtd" <linux-mtd@lists.infradead.org>, "linux-kernel" <linux-kernel@vger.kernel.org> > Gesendet: Dienstag, 11. Januar 2022 12:44:49 > Betreff: Re: [PATCH v6 12/15] ubi: fastmap: Add all fastmap pebs into 'ai->fastmap' when fm->used_blocks>=2
> 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 * find any outdated fastmap anchors, hence we erase the 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 * outdated fastmap anchor PEBs synchronously here.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 outdated fastmap PEBs cannot be erased.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'
I fear, I'm unable to follow your thoughts. ubi_wl_init() is called in both cases, with and without fastmap. And ai->fastmap contains all anchor PEBs that scan_fast() found. This can be the most recent but also outdated anchor PEBs.
Thanks, //richard
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