gentoo-overlay/sys-fs/zfs-kmod/files/zfs-kmod-0.6.5-discard-on-zvol-fix.patch

From 96165264ad0afe7a5d440ef49f9712a188486266 Mon Sep 17 00:00:00 2001
From: Richard Yao <ryao@gentoo.org>
Date: Fri, 18 Sep 2015 08:32:52 -0400
Subject: [PATCH] Discard on zvols should not exceed the length of a block

37f9dac592bf5889c3efb305c48ac39b4c7dd140 replaced the end-start
calculation with a cached value, but neglected to update it on discard
operations. This can cause us to discard data not requested, causing
data loss on zvols.

Reported-by: Richard Connon <richard.connon@zynstra.com>
Signed-off-by: Richard Yao <ryao@gentoo.org>
---
 module/zfs/zvol.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
index 492f8ff..c5a8071 100644
--- a/module/zfs/zvol.c
+++ b/module/zfs/zvol.c
@@ -661,6 +661,7 @@ zvol_discard(struct bio *bio)
 	if (!(bio->bi_rw & REQ_SECURE)) {
 		start = P2ROUNDUP(start, zv->zv_volblocksize);
 		end = P2ALIGN(end, zv->zv_volblocksize);
+		size = end - start;
 	}
 #endif
 
-- 
2.4.6