Illumos 5818 - zfs {ref}compressratio is incorrect with 4k sector size

5818 zfs {ref}compressratio is incorrect with 4k sector size
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Richard Elling <richard.elling@richardelling.com>
Reviewed by: Steven Hartland <killing@multiplay.co.uk>
Approved by: Albert Lee <trisk@omniti.com>

References:
  https://www.illumos.org/issues/5818
  https://github.com/illumos/illumos-gate/commit/81cd5c5

Ported-by: Don Brady <don.brady@intel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3432

module/zfs/spa.c

@@ -2245,6 +2245,8 @@ spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
 		return (error);
 
 	ASSERT(spa->spa_root_vdev == rvd);
+	ASSERT3U(spa->spa_min_ashift, >=, SPA_MINBLOCKSHIFT);
+	ASSERT3U(spa->spa_max_ashift, <=, SPA_MAXBLOCKSHIFT);
 
 	if (type != SPA_IMPORT_ASSEMBLE) {
 		ASSERT(spa_guid(spa) == pool_guid);

module/zfs/spa_misc.c

@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2014 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
  */
@@ -623,6 +623,9 @@ spa_add(const char *name, nvlist_t *config, const char *altroot)
 
 	spa->spa_debug = ((zfs_flags & ZFS_DEBUG_SPA) != 0);
 
+	spa->spa_min_ashift = INT_MAX;
+	spa->spa_max_ashift = 0;
+
 	/*
 	 * As a pool is being created, treat all features as disabled by
 	 * setting SPA_FEATURE_DISABLED for all entries in the feature

module/zfs/vdev.c

@@ -22,7 +22,7 @@
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
- * Copyright (c) 2011, 2014 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -206,8 +206,9 @@ vdev_add_child(vdev_t *pvd, vdev_t *cvd)
 	size_t oldsize, newsize;
 	uint64_t id = cvd->vdev_id;
 	vdev_t **newchild;
+	spa_t *spa = cvd->vdev_spa;
 
-	ASSERT(spa_config_held(cvd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);
+	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
 	ASSERT(cvd->vdev_parent == NULL);
 
 	cvd->vdev_parent = pvd;
@@ -1336,6 +1337,17 @@ vdev_open(vdev_t *vd)
 		return (error);
 	}
 
+	/*
+	 * Track the min and max ashift values for normal data devices.
+	 */
+	if (vd->vdev_top == vd && vd->vdev_ashift != 0 &&
+	    !vd->vdev_islog && vd->vdev_aux == NULL) {
+		if (vd->vdev_ashift > spa->spa_max_ashift)
+			spa->spa_max_ashift = vd->vdev_ashift;
+		if (vd->vdev_ashift < spa->spa_min_ashift)
+			spa->spa_min_ashift = vd->vdev_ashift;
+	}
+
 	/*
 	 * If a leaf vdev has a DTL, and seems healthy, then kick off a
 	 * resilver.  But don't do this if we are doing a reopen for a scrub,

module/zfs/zio.c

@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2014 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
  * Copyright (c) 2011 Nexenta Systems, Inc. All rights reserved.
  */
 
@@ -1195,19 +1195,26 @@ zio_write_bp_init(zio_t *zio)
 			return (ZIO_PIPELINE_CONTINUE);
 		} else {
 			/*
-			 * Round up compressed size to MINBLOCKSIZE and
-			 * zero the tail.
+			 * Round up compressed size up to the ashift
+			 * of the smallest-ashift device, and zero the tail.
+			 * This ensures that the compressed size of the BP
+			 * (and thus compressratio property) are correct,
+			 * in that we charge for the padding used to fill out
+			 * the last sector.
 			 */
-			size_t rounded =
-			    P2ROUNDUP(psize, (size_t)SPA_MINBLOCKSIZE);
-			if (rounded > psize) {
-				bzero((char *)cbuf + psize, rounded - psize);
-				psize = rounded;
-			}
-			if (psize == lsize) {
+			size_t rounded;
+
+			ASSERT3U(spa->spa_min_ashift, >=, SPA_MINBLOCKSHIFT);
+
+			rounded = (size_t)P2ROUNDUP(psize,
+			    1ULL << spa->spa_min_ashift);
+			if (rounded >= lsize) {
 				compress = ZIO_COMPRESS_OFF;
 				zio_buf_free(cbuf, lsize);
+				psize = lsize;
 			} else {
+				bzero((char *)cbuf + psize, rounded - psize);
+				psize = rounded;
 				zio_push_transform(zio, cbuf,
 				    psize, lsize, NULL);
 			}