linux-kernel - [PATCH 2/4] dm-writecache: count the number of blocks read, not the number of read bios

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.LRH.2.02.2207111630310.5249@file01.intranet.prod.int.rdu2.redhat.com>
Date:   Mon, 11 Jul 2022 16:30:52 -0400 (EDT)
From:   Mikulas Patocka <mpatocka@...hat.com>
To:     Yu Kuai <yukuai1@...weicloud.com>,
        Mike Snitzer <msnitzer@...hat.com>
cc:     agk@...hat.com, dm-devel@...hat.com, linux-kernel@...r.kernel.org,
        yukuai3@...wei.com, yi.zhang@...wei.com
Subject: [PATCH 2/4] dm-writecache: count the number of blocks read, not the
 number of read bios

Change dm-writecache, so that it counts the number of blocks read instead
of the number of read bios. Bios can be split and requeued using the
dm_accept_partial_bio function, so counting of bios provided inaccurate
results.

Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
Reported-by: Yu Kuai <yukuai1@...weicloud.com>

Index: linux-2.6/drivers/md/dm-writecache.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-writecache.c
+++ linux-2.6/drivers/md/dm-writecache.c
@@ -1365,6 +1365,7 @@ read_next_block:
 		}
 	} else {
 		writecache_map_remap_origin(wc, bio, e);
+		wc->stats.reads += (bio->bi_iter.bi_size - wc->block_size) >> wc->block_size_bits;
 		map_op = WC_MAP_REMAP_ORIGIN;
 	}
 
Index: linux-2.6/Documentation/admin-guide/device-mapper/writecache.rst
===================================================================
--- linux-2.6.orig/Documentation/admin-guide/device-mapper/writecache.rst
+++ linux-2.6/Documentation/admin-guide/device-mapper/writecache.rst
@@ -78,8 +78,8 @@ Status:
 2. the number of blocks
 3. the number of free blocks
 4. the number of blocks under writeback
-5. the number of read requests
-6. the number of read requests that hit the cache
+5. the number of read blocks
+6. the number of read blocks that hit the cache
 7. the number of write requests
 8. the number of write requests that hit uncommitted block
 9. the number of write requests that hit committed block