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@xxxxxxxxxx>
Reviewed-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
---
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@xxxxxxxxxxx> (maintainer:MEMORY TECHNOLOGY DEVICES (MTD))
Richard Weinberger <richard@xxxxxx> (maintainer:MEMORY TECHNOLOGY DEVICES (MTD))
Vignesh Raghavendra <vigneshr@xxxxxx> (maintainer:MEMORY TECHNOLOGY DEVICES (MTD))
linux-mtd@xxxxxxxxxxxxxxxxxxx (open list:MEMORY TECHNOLOGY DEVICES (MTD))
linux-kernel@xxxxxxxxxxxxxxx (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@xxxxxxxxxxxxxxx and emailed you,
At v4, Cc: stable@xxxxxxxxxxxxxxx was deleted, but forgot to remove you
from the recipient list
I'm very sorry to bother you
Thanks
Xiaoming Ni
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