From: Xiaoming Ni <nixiaoming@huawei.com>
To: <miquel.raynal@bootlin.com>, <richard@nod.at>, <vigneshr@ti.com>,
<gregkh@linuxfoundation.org>
Cc: <nixiaoming@huawei.com>, <linux-mtd@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <wangle6@huawei.com>,
<zhangweimin12@huawei.com>, <yebin10@huawei.com>,
<houtao1@huawei.com>, <stable@kernel.org>
Subject: [PATCH v3] mtd:fix cache_state to avoid writing to bad blocks repeatedly
Date: Mon, 30 Mar 2020 21:45:25 +0800 [thread overview]
Message-ID: <1585575925-84017-1-git-send-email-nixiaoming@huawei.com> (raw)
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>
Cc: stable@vger.kernel.org
---
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;
}
--
1.8.5.6
next reply other threads:[~2020-03-30 13:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-30 13:45 Xiaoming Ni [this message]
2020-03-30 13:52 ` [PATCH v3] mtd:fix cache_state to avoid writing to bad blocks repeatedly Miquel Raynal
2020-03-30 14:25 ` Xiaoming Ni
2020-03-30 14:55 ` Miquel Raynal
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