OpenZFS 8600 - ZFS channel programs - snapshot

Authored by: Chris Williamson <[email protected]>
Reviewed by: Matthew Ahrens <[email protected]>
Reviewed by: John Kennedy <[email protected]>
Reviewed by: Brad Lewis <[email protected]>
Approved by: Robert Mustacchi <[email protected]>
Ported-by: Don Brady <[email protected]>

ZFS channel programs should be able to create snapshots.
In addition to the base snapshot functionality, this entails extra
logic to handle edge cases which were formerly not possible, such as
creating then destroying a snapshot in the same transaction sync.

OpenZFS-issue: https://www.illumos.org/issues/8600
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/68089b8b

1 files changed, 62 insertions, 9 deletions

diff --git a/module/zfs/zcp_synctask.c b/module/zfs/zcp_synctask.c
index 93797e9f3..ad9bffacb 100644
--- a/module/zfs/zcp_synctask.c
+++ b/module/zfs/zcp_synctask.c
@@ -39,10 +39,10 @@ typedef int (zcp_synctask_func_t)(lua_State *, boolean_t, nvlist_t *);
 typedef struct zcp_synctask_info {
 	const char *name;
 	zcp_synctask_func_t *func;
-	zfs_space_check_t space_check;
-	int blocks_modified;
 	const zcp_arg_t pargs[4];
 	const zcp_arg_t kwargs[2];
+	zfs_space_check_t space_check;
+	int blocks_modified;
 } zcp_synctask_info_t;
 
 /*
@@ -91,8 +91,6 @@ static int zcp_synctask_destroy(lua_State *, boolean_t, nvlist_t *);
 static zcp_synctask_info_t zcp_synctask_destroy_info = {
 	.name = "destroy",
 	.func = zcp_synctask_destroy,
-	.space_check = ZFS_SPACE_CHECK_NONE,
-	.blocks_modified = 0,
 	.pargs = {
 	    {.za_name = "filesystem | snapshot", .za_lua_type = LUA_TSTRING},
 	    {NULL, 0}
@@ -100,7 +98,9 @@ static zcp_synctask_info_t zcp_synctask_destroy_info = {
 	.kwargs = {
 	    {.za_name = "defer", .za_lua_type = LUA_TBOOLEAN},
 	    {NULL, 0}
-	}
+	},
+	.space_check = ZFS_SPACE_CHECK_NONE,
+	.blocks_modified = 0
 };
 
 /* ARGSUSED */
@@ -140,19 +140,19 @@ zcp_synctask_destroy(lua_State *state, boolean_t sync, nvlist_t *err_details)
 	return (err);
 }
 
-static int zcp_synctask_promote(lua_State *, boolean_t, nvlist_t *err_details);
+static int zcp_synctask_promote(lua_State *, boolean_t, nvlist_t *);
 static zcp_synctask_info_t zcp_synctask_promote_info = {
 	.name = "promote",
 	.func = zcp_synctask_promote,
-	.space_check = ZFS_SPACE_CHECK_RESERVED,
-	.blocks_modified = 3,
 	.pargs = {
 	    {.za_name = "clone", .za_lua_type = LUA_TSTRING},
 	    {NULL, 0}
 	},
 	.kwargs = {
 	    {NULL, 0}
-	}
+	},
+	.space_check = ZFS_SPACE_CHECK_RESERVED,
+	.blocks_modified = 3
 };
 
 static int
@@ -208,6 +208,58 @@ zcp_synctask_rollback(lua_State *state, boolean_t sync, nvlist_t *err_details)
 	return (err);
 }
 
+static int zcp_synctask_snapshot(lua_State *, boolean_t, nvlist_t *);
+static zcp_synctask_info_t zcp_synctask_snapshot_info = {
+	.name = "snapshot",
+	.func = zcp_synctask_snapshot,
+	.pargs = {
+	    {.za_name = "filesystem@snapname | volume@snapname",
+	    .za_lua_type = LUA_TSTRING},
+	    {NULL, 0}
+	},
+	.kwargs = {
+	    {NULL, 0}
+	},
+	.space_check = ZFS_SPACE_CHECK_NORMAL,
+	.blocks_modified = 3
+};
+
+/* ARGSUSED */
+static int
+zcp_synctask_snapshot(lua_State *state, boolean_t sync, nvlist_t *err_details)
+{
+	int err;
+	dsl_dataset_snapshot_arg_t ddsa = { 0 };
+	const char *dsname = lua_tostring(state, 1);
+	zcp_run_info_t *ri = zcp_run_info(state);
+
+	/*
+	 * We only allow for a single snapshot rather than a list, so the
+	 * error list output is unnecessary.
+	 */
+	ddsa.ddsa_errors = NULL;
+	ddsa.ddsa_props = NULL;
+	ddsa.ddsa_cr = ri->zri_cred;
+	ddsa.ddsa_snaps = fnvlist_alloc();
+	fnvlist_add_boolean(ddsa.ddsa_snaps, dsname);
+
+	/*
+	 * On old pools, the ZIL must not be active when a snapshot is created,
+	 * but we can't suspend the ZIL because we're already in syncing
+	 * context.
+	 */
+	if (spa_version(ri->zri_pool->dp_spa) < SPA_VERSION_FAST_SNAP) {
+		return (ENOTSUP);
+	}
+
+	err = zcp_sync_task(state, dsl_dataset_snapshot_check,
+	    dsl_dataset_snapshot_sync, &ddsa, sync, dsname);
+
+	fnvlist_free(ddsa.ddsa_snaps);
+
+	return (err);
+}
+
 void
 zcp_synctask_wrapper_cleanup(void *arg)
 {
@@ -279,6 +331,7 @@ zcp_load_synctask_lib(lua_State *state, boolean_t sync)
 		&zcp_synctask_destroy_info,
 		&zcp_synctask_promote_info,
 		&zcp_synctask_rollback_info,
+		&zcp_synctask_snapshot_info,
 		NULL
 	};