svn commit: r320452 - in head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs: . sys

[Andriy Gapon]

Author: avg
Date: Wed Jun 28 13:59:20 2017
New Revision: 320452
URL: https://svnweb.freebsd.org/changeset/base/320452

Log:
  fix an architectural problem introduced in r320156, ZFS ABD import
  
  The implementation of ZFS refcount_t uses the emulated illumos mutex
  (the sx lock) and the waiting memory allocation when ZFS_DEBUG is
  enabled.  This makes refcount_t unsuitable for use in GEOM g_up
  thread where sleeping is prohibited.
  
  When importing the ABD change I modified vdev_geom using illumos
  vdev_disk as an example.  As a result, I added a call to abd_return_buf
  in vdev_geom_io_intr.  The latter is called on g_up thread while the
  former uses refcount_t.
  
  This change fixes the problem by deferring the abd_return_buf call to
  the previously unused vdev_geom_io_done that is called on a ZFS zio
  taskqueue thread where sleeping is allowed.
  
  A side bonus of this change is that now a vdev zio has a pointer
  to its corresponding bio while the zio is active.
  
  Reported by:	Shawn Webb <shawn.webb at hardenedbsd.org>
  Tested by:	Shawn Webb <shawn.webb at hardenedbsd.org>
  MFC after:	1 week
  X-MFC with:	r320156

Modified:
  head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h
  head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c

Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h	Wed Jun 28 13:56:15 2017	(r320451)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio.h	Wed Jun 28 13:59:20 2017	(r320452)
@@ -453,6 +453,10 @@ struct zio {
 	avl_node_t	io_alloc_node;
 	zio_alloc_list_t 	io_alloc_list;
 
+#ifdef __FreeBSD__
+	struct bio	*io_bio;
+#endif
+
 	/* Internal pipeline state */
 	enum zio_flag	io_flags;
 	enum zio_stage	io_stage;

Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c	Wed Jun 28 13:56:15 2017	(r320451)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c	Wed Jun 28 13:59:20 2017	(r320452)
@@ -989,13 +989,6 @@ vdev_geom_io_intr(struct bio *bp)
 		break;
 	}
 
-	if (zio->io_type == ZIO_TYPE_READ) {
-		abd_return_buf_copy(zio->io_abd, bp->bio_data, zio->io_size);
-	} else if (zio->io_type == ZIO_TYPE_WRITE) {
-		abd_return_buf(zio->io_abd, bp->bio_data, zio->io_size);
-	}
-
-	g_destroy_bio(bp);
 	zio_delay_interrupt(zio);
 }
 
@@ -1087,6 +1080,7 @@ sendreq:
 		break;
 	}
 	bp->bio_done = vdev_geom_io_intr;
+	zio->io_bio = bp;
 
 	g_io_request(bp, cp);
 }
@@ -1094,6 +1088,15 @@ sendreq:
 static void
 vdev_geom_io_done(zio_t *zio)
 {
+	struct bio *bp = zio->io_bio;
+
+	if (zio->io_type == ZIO_TYPE_READ) {
+		abd_return_buf_copy(zio->io_abd, bp->bio_data, zio->io_size);
+	} else if (zio->io_type == ZIO_TYPE_WRITE) {
+		abd_return_buf(zio->io_abd, bp->bio_data, zio->io_size);
+	}
+
+	g_destroy_bio(bp);
 }
 
 static void