[PATCH 3/3] block: enable long IO requests report by default

[Denis V. Lunev]

Latency threshold is set to 10 seconds following guest request timeout
on legacy storage controller.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Max Reitz <mreitz@redhat.com>
---
 blockdev.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/blockdev.c b/blockdev.c
index 66158d1292..733fdd36da 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -622,8 +622,13 @@ static BlockBackend *blockdev_init(const char *file, QDict 
*bs_opts,
 
         bs->detect_zeroes = detect_zeroes;
 
+        /*
+         * Set log threshold to 10 seconds. Timeout choosen by observation
+         * of the guest behavior with legacy storage controllers. Linux
+         * could remount FS read-only if journal write takes this time.
+         */
         block_acct_setup(blk_get_stats(blk), account_invalid, account_failed,
-                qemu_opt_get_number(opts, "latency-log-threshold", 0));
+                qemu_opt_get_number(opts, "latency-log-threshold", 10000));
 
         if (!parse_stats_intervals(blk_get_stats(blk), interval_list, errp)) {
             blk_unref(blk);
-- 
2.17.1