Illumos #3035 LZ4 compression support in ZFS and GRUB

3035 LZ4 compression support in ZFS and GRUB

Reviewed by: Matthew Ahrens <[email protected]>
Reviewed by: Christopher Siden <[email protected]>
Reviewed by: George Wilson <[email protected]>
Approved by: Christopher Siden <[email protected]>

References:
  illumos/illumos-gate@a6f561b4aee75d0d028e7b36b151c8ed8a86bc76
  https://www.illumos.org/issues/3035
  http://wiki.illumos.org/display/illumos/LZ4+Compression+In+ZFS

This patch has been slightly modified from the upstream Illumos
version to be compatible with Linux.  Due to the very limited
stack space in the kernel a lz4 workspace kmem cache is used.
Since we are using gcc we are also able to take advantage of the
gcc optimized __builtin_ctz functions.

Support for GRUB has been dropped from this patch.  That code
is available but those changes will need to made to the upstream
GRUB package.

Lastly, several hunks of dead code were dropped for clarity.  They
include the functions real_LZ4_uncompress(), LZ4_compressBound()
and the Visual Studio specific hunks wrapped in _MSC_VER.

Ported-by: Eric Dillmann <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #1217

1 files changed, 109 insertions, 0 deletions

diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index 98b1dd794..e804cce08 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -27,6 +27,7 @@
  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2012 by Delphix. All rights reserved.
  * Copyright (c) 2012, Joyent, Inc. All rights reserved.
+ * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  */
 
 #include <sys/types.h>
@@ -75,6 +76,8 @@
 #include <sys/dmu_objset.h>
 #include <sys/fm/util.h>
 
+#include <sys/zfeature.h>
+
 #include <linux/miscdevice.h>
 
 #include "zfs_namecheck.h"
@@ -128,6 +131,12 @@ static int zfs_fill_zplprops_root(uint64_t, nvlist_t *, nvlist_t *,
     boolean_t *);
 int zfs_set_prop_nvlist(const char *, zprop_source_t, nvlist_t *, nvlist_t **);
 
+static int zfs_prop_activate_feature(dsl_pool_t *dp, zfeature_info_t *feature);
+static int zfs_prop_activate_feature_check(void *arg1, void *arg2,
+    dmu_tx_t *tx);
+static void zfs_prop_activate_feature_sync(void *arg1, void *arg2,
+    dmu_tx_t *tx);
+
 static void
 history_str_free(char *buf)
 {
@@ -2196,6 +2205,40 @@ zfs_prop_set_special(const char *dsname, zprop_source_t source,
 		}
 		break;
 	}
+	case ZFS_PROP_COMPRESSION:
+	{
+		if (intval == ZIO_COMPRESS_LZ4) {
+			zfeature_info_t *feature =
+			    &spa_feature_table[SPA_FEATURE_LZ4_COMPRESS];
+			spa_t *spa;
+			dsl_pool_t *dp;
+
+			if ((err = spa_open(dsname, &spa, FTAG)) != 0)
+				return (err);
+
+			dp = spa->spa_dsl_pool;
+
+			/*
+			 * Setting the LZ4 compression algorithm activates
+			 * the feature.
+			 */
+			if (!spa_feature_is_active(spa, feature)) {
+				if ((err = zfs_prop_activate_feature(dp,
+				    feature)) != 0) {
+					spa_close(spa, FTAG);
+					return (err);
+				}
+			}
+
+			spa_close(spa, FTAG);
+		}
+		/*
+		 * We still want the default set action to be performed in the
+		 * caller, we only performed zfeature settings here.
+		 */
+		err = -1;
+		break;
+	}
 
 	default:
 		err = -1;
@@ -3416,6 +3459,22 @@ zfs_check_settable(const char *dsname, nvpair_t *pair, cred_t *cr)
 			    SPA_VERSION_ZLE_COMPRESSION))
 				return (ENOTSUP);
 
+			if (intval == ZIO_COMPRESS_LZ4) {
+				zfeature_info_t *feature =
+				    &spa_feature_table[
+				    SPA_FEATURE_LZ4_COMPRESS];
+				spa_t *spa;
+
+				if ((err = spa_open(dsname, &spa, FTAG)) != 0)
+					return (err);
+
+				if (!spa_feature_is_enabled(spa, feature)) {
+					spa_close(spa, FTAG);
+					return (ENOTSUP);
+				}
+				spa_close(spa, FTAG);
+			}
+
 			/*
 			 * If this is a bootable dataset then
 			 * verify that the compression algorithm
@@ -3462,6 +3521,56 @@ zfs_check_settable(const char *dsname, nvpair_t *pair, cred_t *cr)
 }
 
 /*
+ * Activates a feature on a pool in response to a property setting. This
+ * creates a new sync task which modifies the pool to reflect the feature
+ * as being active.
+ */
+static int
+zfs_prop_activate_feature(dsl_pool_t *dp, zfeature_info_t *feature)
+{
+	int err;
+
+	/* EBUSY here indicates that the feature is already active */
+	err = dsl_sync_task_do(dp, zfs_prop_activate_feature_check,
+	    zfs_prop_activate_feature_sync, dp->dp_spa, feature, 2);
+
+	if (err != 0 && err != EBUSY)
+		return (err);
+	else
+		return (0);
+}
+
+/*
+ * Checks for a race condition to make sure we don't increment a feature flag
+ * multiple times.
+ */
+/*ARGSUSED*/
+static int
+zfs_prop_activate_feature_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+	spa_t *spa = arg1;
+	zfeature_info_t *feature = arg2;
+
+	if (!spa_feature_is_active(spa, feature))
+		return (0);
+	else
+		return (EBUSY);
+}
+
+/*
+ * The callback invoked on feature activation in the sync task caused by
+ * zfs_prop_activate_feature.
+ */
+static void
+zfs_prop_activate_feature_sync(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+	spa_t *spa = arg1;
+	zfeature_info_t *feature = arg2;
+
+	spa_feature_incr(spa, feature, tx);
+}
+
+/*
  * Removes properties from the given props list that fail permission checks
  * needed to clear them and to restore them in case of a receive error. For each
  * property, make sure we have both set and inherit permissions.