svn commit: r316919 - vendor-sys/illumos/dist/uts/common/fs/zfs

[Andriy Gapon]

Author: avg
Date: Fri Apr 14 18:28:40 2017
New Revision: 316919
URL: https://svnweb.freebsd.org/changeset/base/316919

Log:
  7885 zpool list can report 16.0e for expandsz
  
  illumos/illumos-gate at c040c10cdd1e4eab0fc88203758367dd81e057b7
  https://github.com/illumos/illumos-gate/commit/c040c10cdd1e4eab0fc88203758367dd81e057b7
  
  https://www.illumos.org/issues/7885
    When a member of a RAIDZ has been replaced with a device smaller than the
    original, then the top level vdev can report its expand size as 16.0E.
    The reduced child asize causes the RAIDZ to have a vdev_asize lower than its
    vdev_max_asize which then results in an underflow during the calculation of the
    parents expand size.
    Also for RAIDZ vdevs the sum of their child vdev_min_asize could be smaller
    than the parents vdev_min_size.
    Fixed by: https://github.com/openzfs/openzfs/pull/296
  
  Reviewed by: Matthew Ahrens <mahrens at delphix.com>
  Reviewed by: George Wilson <george.wilson at delphix.com>
  Approved by: Gordon Ross <gordon.w.ross at gmail.com>
  Author: Steven Hartland <steven.hartland at multiplay.co.uk>

Modified:
  vendor-sys/illumos/dist/uts/common/fs/zfs/vdev.c

Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/vdev.c
==============================================================================
--- vendor-sys/illumos/dist/uts/common/fs/zfs/vdev.c	Fri Apr 14 18:27:12 2017	(r316918)
+++ vendor-sys/illumos/dist/uts/common/fs/zfs/vdev.c	Fri Apr 14 18:28:40 2017	(r316919)
@@ -135,7 +135,8 @@ vdev_get_min_asize(vdev_t *vd)
 	 * so each child must provide at least 1/Nth of its asize.
 	 */
 	if (pvd->vdev_ops == &vdev_raidz_ops)
-		return (pvd->vdev_min_asize / pvd->vdev_children);
+		return ((pvd->vdev_min_asize + pvd->vdev_children - 1) /
+		    pvd->vdev_children);
 
 	return (pvd->vdev_min_asize);
 }
@@ -1273,7 +1274,7 @@ vdev_open(vdev_t *vd)
 	vd->vdev_psize = psize;
 
 	/*
-	 * Make sure the allocatable size hasn't shrunk.
+	 * Make sure the allocatable size hasn't shrunk too much.
 	 */
 	if (asize < vd->vdev_min_asize) {
 		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
@@ -1306,12 +1307,21 @@ vdev_open(vdev_t *vd)
 	}
 
 	/*
-	 * If all children are healthy and the asize has increased,
-	 * then we've experienced dynamic LUN growth.  If automatic
-	 * expansion is enabled then use the additional space.
-	 */
-	if (vd->vdev_state == VDEV_STATE_HEALTHY && asize > vd->vdev_asize &&
-	    (vd->vdev_expanding || spa->spa_autoexpand))
+	 * If all children are healthy we update asize if either:
+	 * The asize has increased, due to a device expansion caused by dynamic
+	 * LUN growth or vdev replacement, and automatic expansion is enabled;
+	 * making the additional space available.
+	 *
+	 * The asize has decreased, due to a device shrink usually caused by a
+	 * vdev replace with a smaller device. This ensures that calculations
+	 * based of max_asize and asize e.g. esize are always valid. It's safe
+	 * to do this as we've already validated that asize is greater than
+	 * vdev_min_asize.
+	 */
+	if (vd->vdev_state == VDEV_STATE_HEALTHY &&
+	    ((asize > vd->vdev_asize &&
+	    (vd->vdev_expanding || spa->spa_autoexpand)) ||
+	    (asize < vd->vdev_asize)))
 		vd->vdev_asize = asize;
 
 	vdev_set_min_asize(vd);