From: Mikulas Patocka Date: Mon, 21 Jun 2021 18:48:29 +0000 (-0400) Subject: dm writecache: write at least 4k when committing X-Git-Tag: v5.12.18~8 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0b5187d7245af9e3f7cf48f76b9bfa5fad8cd400;p=thirdparty%2Fkernel%2Fstable.git dm writecache: write at least 4k when committing 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 Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c index d7f402d835860..9e9f1ee141652 100644 --- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -532,7 +532,11 @@ static void ssd_commit_superblock(struct dm_writecache *wc) 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;