On Fri, 15 Jan 2021, J. Bruce Fields wrote:
> Any recommendations? I spent some time with blktrace/blkparse/btt and
> can't make head or tails of them, I'm afraid.
>
> --b.
Hi
Try this patch:
From: Mikulas Patocka <[email protected]>
Fix a thinko in ssd_commit_superblock. region.count is in sectors, not
bytes. This bug doesn't corrupt data, but it causes performance
degradation.
Signed-off-by: Mikulas Patocka <[email protected]>
Fixes: dc8a01ae1dbd ("dm writecache: optimize superblock write")
Cc: [email protected] # v5.7
Reported-by: J. Bruce Fields <[email protected]>
---
drivers/md/dm-writecache.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-2.6/drivers/md/dm-writecache.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-writecache.c 2021-01-23 10:51:31.000000000
+0100
+++ linux-2.6/drivers/md/dm-writecache.c 2021-01-23 15:16:53.000000000
+0100
@@ -523,7 +523,7 @@ static void ssd_commit_superblock(struct
region.bdev = wc->ssd_dev->bdev;
region.sector = 0;
- region.count = PAGE_SIZE;
+ region.count = PAGE_SIZE >> SECTOR_SHIFT;
if (unlikely(region.sector + region.count > wc->metadata_sectors))
region.count = wc->metadata_sectors - region.sector;
--
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