lkml.org 
[lkml]   [2020]   [Mar]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v4] mtd: clear cache_state to avoid writing to bad blocks repeatedly
From
Date
On 2020/3/31 18:05, Greg KH wrote:
> On Tue, Mar 31, 2020 at 09:31:59AM +0800, 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(-)
>
> $ ./scripts/get_maintainer.pl --file drivers/mtd/mtdblock.c
> Miquel Raynal <miquel.raynal@bootlin.com> (maintainer:MEMORY TECHNOLOGY DEVICES (MTD))
> Richard Weinberger <richard@nod.at> (maintainer:MEMORY TECHNOLOGY DEVICES (MTD))
> Vignesh Raghavendra <vigneshr@ti.com> (maintainer:MEMORY TECHNOLOGY DEVICES (MTD))
> linux-mtd@lists.infradead.org (open list:MEMORY TECHNOLOGY DEVICES (MTD))
> linux-kernel@vger.kernel.org (open list)
>
>
> No where on there is my name/email, so why am I getting these?
>
> confused,
>
> greg k-h

At v3, I added Cc: stable@vger.kernel.org and emailed you,
At v4, Cc: stable@vger.kernel.org was deleted, but forgot to remove you
from the recipient list
I'm very sorry to bother you
Thanks
Xiaoming Ni

\
 
 \ /
  Last update: 2020-03-31 13:07    [W:0.069 / U:1.340 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site