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Date:      Mon, 10 Apr 2017 17:15:59 +0000 (UTC)
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r316681 - head/sys/geom/mirror
Message-ID:  <201704101715.v3AHFxlq046835@repo.freebsd.org>
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Author: markj
Date: Mon Apr 10 17:15:59 2017
New Revision: 316681
URL: https://svnweb.freebsd.org/changeset/base/316681

Log:
  Handle NULL entries in gmirror disk ds_bios arrays.
  
  Entries may be removed and freed if an I/O error occurs during mirror
  synchronization, so we cannot assume that all entries of ds_bios are
  valid.
  
  Also ensure that a synchronization BIO's array index is preserved after
  a successful write.
  
  Reported and tested by:	pho
  MFC after:	2 weeks
  Sponsored by:	Dell EMC Isilon

Modified:
  head/sys/geom/mirror/g_mirror.c

Modified: head/sys/geom/mirror/g_mirror.c
==============================================================================
--- head/sys/geom/mirror/g_mirror.c	Mon Apr 10 16:09:19 2017	(r316680)
+++ head/sys/geom/mirror/g_mirror.c	Mon Apr 10 17:15:59 2017	(r316681)
@@ -1304,11 +1304,13 @@ g_mirror_sync_release(struct g_mirror_so
 static void
 g_mirror_sync_request_free(struct g_mirror_disk *disk, struct bio *bp)
 {
-	int i;
+	int idx;
 
 	if (disk != NULL && disk->d_sync.ds_bios != NULL) {
-		i = (int)(uintptr_t)bp->bio_caller1;
-		disk->d_sync.ds_bios[i] = NULL;
+		idx = (int)(uintptr_t)bp->bio_caller1;
+		KASSERT(disk->d_sync.ds_bios[idx] == bp,
+		    ("unexpected sync BIO at %p:%d", disk, idx));
+		disk->d_sync.ds_bios[idx] = NULL;
 	}
 	free(bp->bio_data, M_MIRROR);
 	g_destroy_bio(bp);
@@ -1375,7 +1377,7 @@ g_mirror_sync_request(struct bio *bp)
 	    {
 		off_t offset;
 		void *data;
-		int i;
+		int i, idx;
 
 		KFAIL_POINT_ERROR(DEBUG_FP, g_mirror_sync_request_write,
 		    bp->bio_error);
@@ -1413,6 +1415,7 @@ g_mirror_sync_request(struct bio *bp)
 
 		/* Send next synchronization request. */
 		data = bp->bio_data;
+		idx = (int)(uintptr_t)bp->bio_caller1;
 		g_reset_bio(bp);
 		bp->bio_cmd = BIO_READ;
 		bp->bio_offset = sync->ds_offset;
@@ -1422,6 +1425,7 @@ g_mirror_sync_request(struct bio *bp)
 		bp->bio_data = data;
 		bp->bio_from = sync->ds_consumer;
 		bp->bio_to = sc->sc_provider;
+		bp->bio_caller1 = (void *)(uintptr_t)idx;
 		G_MIRROR_LOGREQ(3, bp, "Sending synchronization request.");
 		sync->ds_consumer->index++;
 		/*
@@ -1439,7 +1443,7 @@ g_mirror_sync_request(struct bio *bp)
 		offset = sc->sc_mediasize;
 		for (i = 0; i < g_mirror_syncreqs; i++) {
 			bp = sync->ds_bios[i];
-			if (bp->bio_offset < offset)
+			if (bp != NULL && bp->bio_offset < offset)
 				offset = bp->bio_offset;
 		}
 		if (sync->ds_offset_done + (MAXPHYS * 100) < offset) {

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