On 2020/3/30 21:52, Miquel Raynal wrote:
Hi Xiaoming,
Xiaoming Ni <nixiaoming@xxxxxxxxxx> wrote on Mon, 30 Mar 2020 21:45:25
+0800:
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>
Cc: stable@xxxxxxxxxxxxxxx
Still missing:
* Fixes: tag
* Wrong title prefix
Fixes: 1da177e4c3f41524e88 "Linux-2.6.12-rc2"
Is it described like this?
Do I need to go to
https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git
to trace back the older commit records?
Thanks
Xiaoming Ni
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