Messages in this thread | | | Subject | ping; [PATCH v4] mtd: clear cache_state to avoid writing to bad blocks repeatedly | From | Xiaoming Ni <> | Date | Thu, 7 May 2020 15:53:32 +0800 |
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ping
On 2020/3/31 9:31, Xiaoming Ni wrote: > The function call process is as follows: > mtd_blktrans_work() > while (1) > do_blktrans_request() > mtdblock_writesect() > do_cached_write() > write_cached_data() /*if cache_state is STATE_DIRTY*/ > erase_write() > > write_cached_data() returns failure without modifying cache_state > and cache_offset. So when do_cached_write() is called again, > write_cached_data() will be called again to perform erase_write() > on the same cache_offset. > > But if this cache_offset points to a bad block, erase_write() will > always return -EIO. Writing to this mtdblk is equivalent to losing > the current data, and repeatedly writing to the bad block. > > Repeatedly writing a bad block has no real benefits, > but brings some negative effects: > 1 Lost subsequent data > 2 Loss of flash device life > 3 erase_write() bad blocks are very time-consuming. For example: > the function do_erase_oneblock() in chips/cfi_cmdset_0020.c or > chips/cfi_cmdset_0002.c may take more than 20 seconds to return > > Therefore, when erase_write() returns -EIO in write_cached_data(), > clear cache_state to avoid writing to bad blocks repeatedly. > > Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com> > Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com> > --- > drivers/mtd/mtdblock.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/drivers/mtd/mtdblock.c b/drivers/mtd/mtdblock.c > index 078e0f6..32e52d8 100644 > --- a/drivers/mtd/mtdblock.c > +++ b/drivers/mtd/mtdblock.c > @@ -89,8 +89,6 @@ static int write_cached_data (struct mtdblk_dev *mtdblk) > > ret = erase_write (mtd, mtdblk->cache_offset, > mtdblk->cache_size, mtdblk->cache_data); > - if (ret) > - return ret; > > /* > * Here we could arguably set the cache state to STATE_CLEAN. > @@ -98,9 +96,14 @@ static int write_cached_data (struct mtdblk_dev *mtdblk) > * be notified if this content is altered on the flash by other > * means. Let's declare it empty and leave buffering tasks to > * the buffer cache instead. > + * > + * If this cache_offset points to a bad block, data cannot be > + * written to the device. Clear cache_state to avoid writing to > + * bad blocks repeatedly. > */ > - mtdblk->cache_state = STATE_EMPTY; > - return 0; > + if (ret == 0 || ret == -EIO) > + mtdblk->cache_state = STATE_EMPTY; > + return ret; > } > > >
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