From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Wed, 6 Mar 2019 17:17:53 +0000 (-0800)
Subject: Fix race in vdev_initialize_thread
X-Git-Tag: zfs-0.8.0-rc4~88
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=96ebc5a1a4cc57806882e4e9b38c49ba8a5bdfda;p=zfs

Fix race in vdev_initialize_thread

Before allowing new allocations to the metaslab we need to ensure
that any issued initializing writes have been synced.  Otherwise,
it's possible for metaslab_block_alloc() to allocate a range which
is about to be overwritten by an initializing IO.

Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Reviewed-by: Tim Chase <tim@chase2k.com>
Reviewed-by: George Wilson <george.wilson@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #8461
---

diff --git a/module/zfs/vdev_initialize.c b/module/zfs/vdev_initialize.c
index a69eca354..bec89a28e 100644
--- a/module/zfs/vdev_initialize.c
+++ b/module/zfs/vdev_initialize.c
@@ -628,6 +628,13 @@ vdev_initialize_thread(void *arg)
 
 		spa_config_exit(spa, SCL_CONFIG, FTAG);
 		error = vdev_initialize_ranges(vd, deadbeef);
+
+		/*
+		 * Wait for the outstanding IO to be synced to prevent
+		 * newly allocated blocks from being overwritten.
+		 */
+		txg_wait_synced(spa_get_dsl(spa), 0);
+
 		vdev_initialize_ms_unmark(msp);
 		spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);