This is a note to let you know that I've just added the patch titled
dm writecache: write at least 4k when committing
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-writecache-write-at-least-4k-when-committing.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 867de40c4c23e6d7f89f9ce4272a5d1b1484c122 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Date: Mon, 21 Jun 2021 14:48:29 -0400
Subject: dm writecache: write at least 4k when committing
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
commit 867de40c4c23e6d7f89f9ce4272a5d1b1484c122 upstream.
SSDs perform badly with sub-4k writes (because they perfrorm
read-modify-write internally), so make sure writecache writes at least
4k when committing.
Fixes: 991bd8d7bc78 ("dm writecache: commit just one block, not a full page")
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-writecache.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -532,7 +532,11 @@ static void ssd_commit_superblock(struct
region.bdev = wc->ssd_dev->bdev;
region.sector = 0;
- region.count = wc->block_size >> SECTOR_SHIFT;
+ region.count = max(4096U, wc->block_size) >> SECTOR_SHIFT;
+
+ if (unlikely(region.sector + region.count > wc->metadata_sectors))
+ region.count = wc->metadata_sectors - region.sector;
+
region.sector += wc->start_sector;
req.bi_op = REQ_OP_WRITE;
Patches currently in stable-queue which might be from mpatocka@xxxxxxxxxx are
queue-5.10/dm-writecache-don-t-split-bios-when-overwriting-cont.patch
queue-5.10/dm-writecache-write-at-least-4k-when-committing.patch
queue-5.10/dm-writecache-commit-just-one-block-not-a-full-page.patch
queue-5.10/dm-writecache-flush-origin-device-when-writing-and-cache-is-full.patch
