Illumos #3145, #3212

3145 single-copy arc
3212 ztest: race condition between vdev_online() and spa_vdev_remove()

Reviewed by: Matt Ahrens <[email protected]>
Reviewed by: Adam Leventhal <[email protected]>
Reviewed by: Eric Schrock <[email protected]>
Reviewed by: Justin T. Gibbs <[email protected]>
Approved by: Eric Schrock <[email protected]>

References:
  illumos-gate/commit/9253d63df408bb48584e0b1abfcc24ef2472382e
  illumos changeset: 13840:97fd5cdf328a
  https://www.illumos.org/issues/3145
  https://www.illumos.org/issues/3212

Ported-by: Brian Behlendorf <[email protected]>
Closes #989
Closes #1137

1 files changed, 18 insertions, 1 deletions

diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c
index 99f728f4b..205abaada 100644
--- a/module/zfs/dbuf.c
+++ b/module/zfs/dbuf.c
@@ -2189,7 +2189,24 @@ dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
 			dbuf_evict(db);
 		} else {
 			VERIFY(arc_buf_remove_ref(db->db_buf, db) == 0);
-			if (!DBUF_IS_CACHEABLE(db))
+
+			/*
+			 * A dbuf will be eligible for eviction if either the
+			 * 'primarycache' property is set or a duplicate
+			 * copy of this buffer is already cached in the arc.
+			 *
+			 * In the case of the 'primarycache' a buffer
+			 * is considered for eviction if it matches the
+			 * criteria set in the property.
+			 *
+			 * To decide if our buffer is considered a
+			 * duplicate, we must call into the arc to determine
+			 * if multiple buffers are referencing the same
+			 * block on-disk. If so, then we simply evict
+			 * ourselves.
+			 */
+			if (!DBUF_IS_CACHEABLE(db) ||
+			    arc_buf_eviction_needed(db->db_buf))
 				dbuf_clear(db);
 			else
 				mutex_exit(&db->db_mtx);