Add feature-commit-cb branch

.topdeps

@@ -0,0 +1 @@
+master

.topmsg

@@ -0,0 +1,12 @@
+From: Brian Behlendorf <behlendorf1@llnl.gov>
+Subject: [PATCH] feature commit cb
+
+ZFS commit callbacks (v3) some version of this support is expected
+to appear in an official release from the core ZFS team.
+
+NOTE: The ztest test case was dropped because it assumed userspace
+pthreads support.  We should certainly keep the test case but the
+user space modification should be properly written to handle and
+kernel space build as well.
+
+Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

zfs/lib/libzcommon/include/sys/dmu.h

@@ -66,6 +66,7 @@ struct objset_impl;
 typedef struct objset objset_t;
 typedef struct dmu_tx dmu_tx_t;
 typedef struct dsl_dir dsl_dir_t;
+typedef void dmu_callback_func_t(void *dcb_data, int error);
 
 typedef enum dmu_object_type {
 	DMU_OT_NONE,
@@ -416,6 +417,32 @@ int dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how);
 void dmu_tx_wait(dmu_tx_t *tx);
 void dmu_tx_commit(dmu_tx_t *tx);
 
+/*
+ * To add a commit callback, you must first call dmu_tx_callback_data_create().
+ * This will return a pointer to a memory area of size "bytes" (which can be 0,
+ * or just the size of a pointer if there is a large or existing external data
+ * struct to be referenced) that the caller and the callback can use to exchange
+ * data.
+ *
+ * The callback can then be registered by calling dmu_tx_callback_commit_add()
+ * with the pointer returned by dmu_tx_callback_data_create() passed in the
+ * dcb_data argument. The transaction must be already created, but it cannot
+ * be committed or aborted. It can be assigned to a txg or not.
+ *
+ * The callback will be called after the transaction has been safely written
+ * to stable storage and will also be called if the dmu_tx is aborted.
+ * If there is any error which prevents the transaction from being committed
+ * to disk, the callback will be called with a value of error != 0.
+ *
+ * When the callback data is no longer needed, it must be destroyed by the
+ * caller's code with dmu_tx_callback_data_destroy(). This is typically done at
+ * the end of the callback function.
+ */
+void *dmu_tx_callback_data_create(size_t bytes);
+int dmu_tx_callback_commit_add(dmu_tx_t *tx, dmu_callback_func_t *dcb_func,
+    void *dcb_data);
+int dmu_tx_callback_data_destroy(void *dcb_data);
+
 /*
  * Free up the data blocks for a defined range of a file.  If size is
  * zero, the range from offset to end-of-file is freed.

zfs/lib/libzcommon/include/sys/dmu_impl.h

@@ -230,6 +230,19 @@ extern "C" {
 struct objset;
 struct dmu_pool;
 
+#define DMU_CALLBACK_MAGIC 0xca11bac0ca11bacfull
+
+#define container_of(ptr, type, member) \
+    ((type *)((char *)(ptr) - offsetof(type, member)))
+
+typedef struct dmu_callback {
+	list_node_t         dcb_node;    /* linked to tx_callbacks list */
+	uint64_t            dcb_magic;   /* magic number to verify header */
+	dmu_callback_func_t *dcb_func;   /* caller function pointer */
+	size_t              dcb_bytes;   /* caller private data size */
+	char                dcb_data[0]; /* caller private data */
+} dmu_callback_t;
+
 #ifdef	__cplusplus
 }
 #endif

zfs/lib/libzcommon/include/sys/dmu_tx.h

@@ -59,6 +59,7 @@ struct dmu_tx {
 	txg_handle_t tx_txgh;
 	void *tx_tempreserve_cookie;
 	struct dmu_tx_hold *tx_needassign_txh;
+	list_t tx_callbacks; /* list of dmu_callback_t on this dmu_tx */
 	uint8_t tx_anyobj;
 	int tx_err;
 #ifdef ZFS_DEBUG
@@ -107,6 +108,11 @@ void dmu_tx_abort(dmu_tx_t *tx);
 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
 void dmu_tx_wait(dmu_tx_t *tx);
 
+void *dmu_tx_callback_data_create(size_t bytes);
+int dmu_tx_callback_commit_add(dmu_tx_t *tx, dmu_callback_func_t *dcb_func,
+    void *dcb_data);
+int dmu_tx_callback_data_destroy(void *dcb_data);
+
 /*
  * These routines are defined in dmu_spa.h, and are called by the SPA.
  */

zfs/lib/libzcommon/include/sys/txg.h

@@ -71,6 +71,7 @@ extern void txg_sync_stop(struct dsl_pool *dp);
 extern uint64_t txg_hold_open(struct dsl_pool *dp, txg_handle_t *txghp);
 extern void txg_rele_to_quiesce(txg_handle_t *txghp);
 extern void txg_rele_to_sync(txg_handle_t *txghp);
+extern void txg_rele_commit_cb(txg_handle_t *txghp, list_t *tx_callbacks);
 extern void txg_suspend(struct dsl_pool *dp);
 extern void txg_resume(struct dsl_pool *dp);
 

zfs/lib/libzcommon/include/sys/txg_impl.h

@@ -39,6 +39,7 @@ struct tx_cpu {
 	kmutex_t	tc_lock;
 	kcondvar_t	tc_cv[TXG_SIZE];
 	uint64_t	tc_count[TXG_SIZE];
+	list_t		tc_callbacks[TXG_SIZE]; /* post-commit callbacks */
 	char		tc_pad[16];
 };
 

zfs/lib/libzpool/dmu_tx.c

@@ -50,6 +50,8 @@ dmu_tx_create_dd(dsl_dir_t *dd)
 		tx->tx_pool = dd->dd_pool;
 	list_create(&tx->tx_holds, sizeof (dmu_tx_hold_t),
 	    offsetof(dmu_tx_hold_t, txh_node));
+	list_create(&tx->tx_callbacks, sizeof (dmu_callback_t),
+	    offsetof(dmu_callback_t, dcb_node));
 #ifdef ZFS_DEBUG
 	refcount_create(&tx->tx_space_written);
 	refcount_create(&tx->tx_space_freed);
@@ -986,6 +988,9 @@ dmu_tx_commit(dmu_tx_t *tx)
 	if (tx->tx_tempreserve_cookie)
 		dsl_dir_tempreserve_clear(tx->tx_tempreserve_cookie, tx);
 
+	if (!list_is_empty(&tx->tx_callbacks))
+		txg_rele_commit_cb(&tx->tx_txgh, &tx->tx_callbacks);
+
 	if (tx->tx_anyobj == FALSE)
 		txg_rele_to_sync(&tx->tx_txgh);
 	list_destroy(&tx->tx_holds);
@@ -998,6 +1003,8 @@ dmu_tx_commit(dmu_tx_t *tx)
 	refcount_destroy_many(&tx->tx_space_freed,
 	    refcount_count(&tx->tx_space_freed));
 #endif
+	ASSERT(list_is_empty(&tx->tx_callbacks));
+	list_destroy(&tx->tx_callbacks);
 	kmem_free(tx, sizeof (dmu_tx_t));
 }
 
@@ -1005,6 +1012,7 @@ void
 dmu_tx_abort(dmu_tx_t *tx)
 {
 	dmu_tx_hold_t *txh;
+	dmu_callback_t *dcb;
 
 	ASSERT(tx->tx_txg == 0);
 
@@ -1016,6 +1024,16 @@ dmu_tx_abort(dmu_tx_t *tx)
 		if (dn != NULL)
 			dnode_rele(dn, tx);
 	}
+
+	while (dcb = list_head(&tx->tx_callbacks)) {
+		list_remove(&tx->tx_callbacks, dcb);
+
+		/*
+		 * Call the callback with an error code. The callback will
+		 * call dmu_tx_callback_data_destroy to free the memory.
+		 */
+		dcb->dcb_func(dcb->dcb_data, ECANCELED);
+	}
 	list_destroy(&tx->tx_holds);
 #ifdef ZFS_DEBUG
 	refcount_destroy_many(&tx->tx_space_written,
@@ -1023,6 +1041,7 @@ dmu_tx_abort(dmu_tx_t *tx)
 	refcount_destroy_many(&tx->tx_space_freed,
 	    refcount_count(&tx->tx_space_freed));
 #endif
+	list_destroy(&tx->tx_callbacks);
 	kmem_free(tx, sizeof (dmu_tx_t));
 }
 
@@ -1032,3 +1051,45 @@ dmu_tx_get_txg(dmu_tx_t *tx)
 	ASSERT(tx->tx_txg != 0);
 	return (tx->tx_txg);
 }
+
+void *
+dmu_tx_callback_data_create(size_t bytes)
+{
+	dmu_callback_t *dcb;
+
+	dcb = kmem_alloc(sizeof (dmu_callback_t) + bytes, KM_SLEEP);
+
+	dcb->dcb_magic = DMU_CALLBACK_MAGIC;
+	dcb->dcb_bytes = bytes;
+
+	return &dcb->dcb_data;
+}
+
+int
+dmu_tx_callback_commit_add(dmu_tx_t *tx, dmu_callback_func_t *dcb_func,
+    void *dcb_data)
+{
+	dmu_callback_t *dcb = container_of(dcb_data, dmu_callback_t, dcb_data);
+
+	if (dcb->dcb_magic != DMU_CALLBACK_MAGIC)
+		return (EINVAL);
+
+	dcb->dcb_func = dcb_func;
+
+	list_insert_tail(&tx->tx_callbacks, dcb);
+
+	return (0);
+}
+
+int
+dmu_tx_callback_data_destroy(void *dcb_data)
+{
+	dmu_callback_t *dcb = container_of(dcb_data, dmu_callback_t, dcb_data);
+
+	if (dcb->dcb_magic != DMU_CALLBACK_MAGIC)
+		return (EINVAL);
+
+	kmem_free(dcb, sizeof (dmu_callback_t) + dcb->dcb_bytes);
+
+	return (0);
+}

zfs/lib/libzpool/txg.c

@@ -28,6 +28,7 @@
 #include <sys/zfs_context.h>
 #include <sys/txg_impl.h>
 #include <sys/dmu_impl.h>
+#include <sys/dmu_tx.h>
 #include <sys/dsl_pool.h>
 #include <sys/callb.h>
 
@@ -66,6 +67,9 @@ txg_init(dsl_pool_t *dp, uint64_t txg)
 		for (i = 0; i < TXG_SIZE; i++) {
 			cv_init(&tx->tx_cpu[c].tc_cv[i], NULL, CV_DEFAULT,
 			    NULL);
+			list_create(&tx->tx_cpu[c].tc_callbacks[i],
+			    sizeof (dmu_callback_t), offsetof(dmu_callback_t,
+			    dcb_node));
 		}
 	}
 
@@ -93,8 +97,11 @@ txg_fini(dsl_pool_t *dp)
 		int i;
 
 		mutex_destroy(&tx->tx_cpu[c].tc_lock);
-		for (i = 0; i < TXG_SIZE; i++)
+		for (i = 0; i < TXG_SIZE; i++) {
 			cv_destroy(&tx->tx_cpu[c].tc_cv[i]);
+			ASSERT(list_is_empty(&tx->tx_cpu[c].tc_callbacks[i]));
+			list_destroy(&tx->tx_cpu[c].tc_callbacks[i]);
+		}
 	}
 
 	kmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t));
@@ -235,6 +242,21 @@ txg_rele_to_sync(txg_handle_t *th)
 	th->th_cpu = NULL;	/* defensive */
 }
 
+void
+txg_rele_commit_cb(txg_handle_t *th, list_t *tx_callbacks)
+{
+	dmu_callback_t *dcb;
+	tx_cpu_t *tc = th->th_cpu;
+	int g = th->th_txg & TXG_MASK;
+
+	mutex_enter(&tc->tc_lock);
+	while (dcb = list_head(tx_callbacks)) {
+		list_remove(tx_callbacks, dcb);
+		list_insert_tail(&tc->tc_callbacks[g], dcb);
+	}
+	mutex_exit(&tc->tc_lock);
+}
+
 static void
 txg_quiesce(dsl_pool_t *dp, uint64_t txg)
 {
@@ -335,6 +357,21 @@ txg_sync_thread(dsl_pool_t *dp)
 		spa_sync(dp->dp_spa, txg);
 		delta = lbolt - start;
 
+		/*
+		 * Call all the callbacks for this txg. The callbacks must
+		 * call dmu_tx_callback_data_destroy to free memory.
+		 */
+		for (int c = 0; c < max_ncpus; c++) {
+			int g = txg & TXG_MASK;
+			tx_cpu_t *tc = &tx->tx_cpu[c];
+			/* No need to lock tx_cpu_t */
+
+			while (dcb = list_head(&tc->tc_callbacks[g])) {
+				list_remove(&tc->tc_callbacks[g], dcb);
+				dcb->dcb_func(dcb->dcb_data, 0);
+			}
+		}
+
 		written = dp->dp_space_towrite[txg & TXG_MASK];
 		dp->dp_space_towrite[txg & TXG_MASK] = 0;
 		ASSERT(dp->dp_tempreserved[txg & TXG_MASK] == 0);
@@ -390,6 +427,7 @@ txg_quiesce_thread(dsl_pool_t *dp)
 {
 	tx_state_t *tx = &dp->dp_tx;
 	callb_cpr_t cpr;
+	dmu_callback_t *dcb;
 
 	txg_thread_enter(tx, &cpr);