diff options
| -rw-r--r-- | drivers/mtd/ubi/build.c | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c index 5ebe280225d..f49e49dc592 100644 --- a/drivers/mtd/ubi/build.c +++ b/drivers/mtd/ubi/build.c @@ -672,7 +672,33 @@ static int io_init(struct ubi_device *ubi) ubi->nor_flash = 1; } - ubi->min_io_size = ubi->mtd->writesize; + /* + * Set UBI min. I/O size (@ubi->min_io_size). We use @mtd->writebufsize + * for these purposes, not @mtd->writesize. At the moment this does not + * matter for NAND, because currently @mtd->writebufsize is equivalent to + * @mtd->writesize for all NANDs. However, some CFI NOR flashes may + * have @mtd->writebufsize which is multiple of @mtd->writesize. + * + * The reason we use @mtd->writebufsize for @ubi->min_io_size is that + * UBI and UBIFS recovery algorithms rely on the fact that if there was + * an unclean power cut, then we can find offset of the last corrupted + * node, align the offset to @ubi->min_io_size, read the rest of the + * eraseblock starting from this offset, and check whether there are + * only 0xFF bytes. If yes, then we are probably dealing with a + * corruption caused by a power cut, if not, then this is probably some + * severe corruption. + * + * Thus, we have to use the maximum write unit size of the flash, which + * is @mtd->writebufsize, because @mtd->writesize is the minimum write + * size, not the maximum. + */ + if (ubi->mtd->type == MTD_NANDFLASH) + ubi_assert(ubi->mtd->writebufsize == ubi->mtd->writesize); + else if (ubi->mtd->type == MTD_NORFLASH) + ubi_assert(ubi->mtd->writebufsize % ubi->mtd->writesize == 0); + + ubi->min_io_size = ubi->mtd->writebufsize; + ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft; /* |