Implemented zpool sync command

This addition will enable us to sync an open TXG to the main pool
on demand. The functionality is similar to 'sync(2)' but 'zpool sync'
will return when data has hit the main storage instead of potentially
just the ZIL as is the case with the 'sync(2)' cmd.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed by: Matthew Ahrens <[email protected]>
Signed-off-by: Alek Pinchuk <[email protected]>
Closes #6122 

1 files changed, 44 insertions, 0 deletions

diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index 268e79714..c6a532123 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -34,6 +34,7 @@
  * Copyright 2016 Toomas Soome <[email protected]>
  * Copyright (c) 2016 Actifio, Inc. All rights reserved.
  * Copyright (c) 2017, loli10K <[email protected]>. All rights reserved.
+ * Copyright (c) 2017 Datto Inc.
  */
 
 /*
@@ -5466,6 +5467,7 @@ zfs_ioc_hold(const char *pool, nvlist_t *args, nvlist_t *errlist)
 static int
 zfs_ioc_get_holds(const char *snapname, nvlist_t *args, nvlist_t *outnvl)
 {
+	ASSERT3P(args, ==, NULL);
 	return (dsl_dataset_get_holds(snapname, outnvl));
 }
 
@@ -5823,6 +5825,44 @@ out:
 	return (error);
 }
 
+/*
+ * Sync the currently open TXG to disk for the specified pool.
+ * This is somewhat similar to 'zfs_sync()'.
+ * For cases that do not result in error this ioctl will wait for
+ * the currently open TXG to commit before returning back to the caller.
+ *
+ * innvl: {
+ *  "force" -> when true, force uberblock update even if there is no dirty data.
+ *             In addition this will cause the vdev configuration to be written
+ *             out including updating the zpool cache file. (boolean_t)
+ * }
+ *
+ * onvl is unused
+ */
+/* ARGSUSED */
+static int
+zfs_ioc_pool_sync(const char *pool, nvlist_t *innvl, nvlist_t *onvl)
+{
+	int err;
+	boolean_t force;
+	spa_t *spa;
+
+	if ((err = spa_open(pool, &spa, FTAG)) != 0)
+		return (err);
+
+	force = fnvlist_lookup_boolean_value(innvl, "force");
+	if (force) {
+		spa_config_enter(spa, SCL_CONFIG, FTAG, RW_WRITER);
+		vdev_config_dirty(spa->spa_root_vdev);
+		spa_config_exit(spa, SCL_CONFIG, FTAG);
+	}
+	txg_wait_synced(spa_get_dsl(spa), 0);
+
+	spa_close(spa, FTAG);
+
+	return (err);
+}
+
 static zfs_ioc_vec_t zfs_ioc_vec[ZFS_IOC_LAST - ZFS_IOC_FIRST];
 
 static void
@@ -5995,6 +6035,10 @@ zfs_ioctl_init(void)
 	    zfs_ioc_recv_new, zfs_secpolicy_recv_new, DATASET_NAME,
 	    POOL_CHECK_SUSPENDED | POOL_CHECK_READONLY, B_TRUE, B_TRUE);
 
+	zfs_ioctl_register("sync", ZFS_IOC_POOL_SYNC,
+	    zfs_ioc_pool_sync, zfs_secpolicy_none, POOL_NAME,
+	    POOL_CHECK_SUSPENDED | POOL_CHECK_READONLY, B_FALSE, B_FALSE);
+
 	/* IOCTLS that use the legacy function signature */
 
 	zfs_ioctl_register_legacy(ZFS_IOC_POOL_FREEZE, zfs_ioc_pool_freeze,