Messages in this thread | | | Date | Tue, 11 Jan 2022 14:56:22 +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 14:23:52 > Betreff: Re: [PATCH v6 12/15] ubi: fastmap: Add all fastmap pebs into 'ai->fastmap' when fm->used_blocks>=2
> 在 2022/1/11 19:57, Richard Weinberger 写道: >> ubi_wl_init() is called in both cases, with and without fastmap. > I agree. > >> And ai->fastmap contains all anchor PEBs that scan_fast() found. >> This can be the most recent but also outdated anchor PEBs. > Is it exists a case that outdated fastmap PEBs are neither counted into > 'fmhdr->erase_peb_count' nor scanned into 'ai->fastmap' after attaching > by fastmap. >
[...] > I think UBI attaches failed by fastmap if kernel goes here. > 1870 err = erase_aeb(ubi, aeb, sync);
Hmm, I think the paranoia check in fastmap.c is too strict these days. if (WARN_ON(count_fastmap_pebs(ai) != ubi->peb_count - ai->bad_peb_count - fm->used_blocks)) goto fail_bad;
It does not account ai->fastmap. So if ai->fastmap contains old anchor PEBs this check will trigger and force falling back to scanning mode. With this check fixed, ubi_wl_init() will erase all old PEBs from ai->fastmap.
So I agree that this code path is wonky and can be cleaned up. But please be extremely careful and give all your changes excessive testing with real workload and power-cuts.
Thanks, //richard
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