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authorXiaoming Ni <nixiaoming@huawei.com>2020-03-31 09:31:59 +0800
committerRichard Weinberger <richard@nod.at>2020-06-05 10:16:14 +0200
commit5788ccf3c84f5587418a80128a3653aa35abf00b (patch)
tree105543ba94960667a75ade8fdcbbdc5d09e40b65 /drivers/mtd
parenteb13fa0227417e84aecc3bd9c029d376e33474d3 (diff)
mtd: clear cache_state to avoid writing to bad blocks repeatedly
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> Signed-off-by: Richard Weinberger <richard@nod.at>
Diffstat (limited to 'drivers/mtd')
-rw-r--r--drivers/mtd/mtdblock.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/mtd/mtdblock.c b/drivers/mtd/mtdblock.c
index 078e0f67377d..32e52d83b961 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;
}