ftl: vss null buffer workaround

Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Kozlowski Mateusz <mateusz.kozlowski@intel.com>
Change-Id: I94ea399ed30fae29f92b4216eaa9209c02b3478b
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/13310
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

include/spdk/ftl.h

@@ -64,6 +64,18 @@ struct spdk_ftl_attrs {
 typedef void (*spdk_ftl_fn)(void *cb_arg, int status);
 typedef void (*spdk_ftl_init_fn)(struct spdk_ftl_dev *dev, void *cb_arg, int status);
 
+/**
+ * Initializes the FTL library.
+ *
+ * @return 0 on success, negative errno otherwise.
+ */
+int spdk_ftl_init(void);
+
+/**
+ * Deinitializes the FTL library.
+ */
+void spdk_ftl_fini(void);
+
 /**
  * Initialize the FTL on the given pair of bdevs - base and cache bdev.
  * Upon receiving a successful completion callback user is free to use I/O calls.

lib/ftl/ftl_core.c

@@ -136,6 +136,35 @@ ftl_core_poller(void *ctx)
 	return SPDK_POLLER_IDLE;
 }
 
+void *g_ftl_write_buf;
+void *g_ftl_read_buf;
+
+int
+spdk_ftl_init(void)
+{
+	g_ftl_write_buf = spdk_zmalloc(FTL_ZERO_BUFFER_SIZE, FTL_ZERO_BUFFER_SIZE, NULL,
+				       SPDK_ENV_LCORE_ID_ANY, SPDK_MALLOC_DMA);
+	if (!g_ftl_write_buf) {
+		return -ENOMEM;
+	}
+
+	g_ftl_read_buf = spdk_zmalloc(FTL_ZERO_BUFFER_SIZE, FTL_ZERO_BUFFER_SIZE, NULL,
+				      SPDK_ENV_LCORE_ID_ANY, SPDK_MALLOC_DMA);
+	if (!g_ftl_read_buf) {
+		spdk_free(g_ftl_write_buf);
+		g_ftl_write_buf = NULL;
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void
+spdk_ftl_fini(void)
+{
+	spdk_free(g_ftl_write_buf);
+	spdk_free(g_ftl_read_buf);
+}
+
 struct spdk_io_channel *
 spdk_ftl_get_io_channel(struct spdk_ftl_dev *dev)
 {

lib/ftl/ftl_core.h

@@ -21,6 +21,13 @@
 #include "ftl_layout.h"
 #include "utils/ftl_log.h"
 
+/* When using VSS on nvcache, FTL sometimes doesn't require the contents of metadata.
+ * Some devices have bugs when sending a NULL pointer as part of metadata when namespace
+ * is formatted with VSS. This buffer is passed to such calls to avoid the bug. */
+#define FTL_ZERO_BUFFER_SIZE 0x100000
+extern void *g_ftl_write_buf;
+extern void *g_ftl_read_buf;
+
 struct spdk_ftl_dev {
 	/* Configuration */
 	struct spdk_ftl_conf		conf;

lib/ftl/ftl_nv_cache_io.h

@@ -43,7 +43,7 @@ ftl_nv_cache_bdev_read_blocks_with_md(struct spdk_ftl_dev *dev,
 				      uint64_t offset_blocks, uint64_t num_blocks,
 				      spdk_bdev_io_completion_cb cb, void *cb_arg)
 {
-	return spdk_bdev_read_blocks_with_md(desc, ch, buf, md,
+	return spdk_bdev_read_blocks_with_md(desc, ch, buf, md ? : g_ftl_read_buf,
 					     offset_blocks, num_blocks,
 					     cb, cb_arg);
 }
@@ -56,7 +56,7 @@ ftl_nv_cache_bdev_write_blocks_with_md(struct spdk_ftl_dev *dev,
 				       uint64_t offset_blocks, uint64_t num_blocks,
 				       spdk_bdev_io_completion_cb cb, void *cb_arg)
 {
-	return spdk_bdev_write_blocks_with_md(desc, ch, buf, md,
+	return spdk_bdev_write_blocks_with_md(desc, ch, buf, md ? : g_ftl_write_buf,
 					      offset_blocks, num_blocks,
 					      cb, cb_arg);
 }

lib/ftl/mngt/ftl_mngt_bdev.c

@@ -228,6 +228,12 @@ ftl_mngt_open_cache_bdev(struct spdk_ftl_dev *dev, struct ftl_mngt_process *mngt
 		goto error;
 	}
 
+	if (ftl_md_xfer_blocks(dev) * dev->cache_md_size > FTL_ZERO_BUFFER_SIZE) {
+		FTL_ERRLOG(dev, "Zero buffer too small for bdev %s metadata transfer\n",
+			   spdk_bdev_get_name(bdev));
+		goto error;
+	}
+
 	ftl_mngt_next_step(mngt);
 	return;
 error:

lib/ftl/spdk_ftl.map

@@ -2,6 +2,8 @@
 	global:
 
 	# public functions
+	spdk_ftl_init;
+	spdk_ftl_fini;
 	spdk_ftl_dev_init;
 	spdk_ftl_dev_free;
 	spdk_ftl_get_default_conf;

module/bdev/ftl/bdev_ftl.c

@@ -36,6 +36,7 @@ struct ftl_deferred_init {
 static LIST_HEAD(, ftl_deferred_init)	g_deferred_init = LIST_HEAD_INITIALIZER(g_deferred_init);
 
 static int bdev_ftl_initialize(void);
+static void bdev_ftl_finish(void);
 static void bdev_ftl_examine(struct spdk_bdev *bdev);
 
 static int
@@ -47,6 +48,7 @@ bdev_ftl_get_ctx_size(void)
 static struct spdk_bdev_module g_ftl_if = {
 	.name		= "ftl",
 	.module_init	= bdev_ftl_initialize,
+	.module_fini	= bdev_ftl_finish,
 	.examine_disk	= bdev_ftl_examine,
 	.get_ctx_size	= bdev_ftl_get_ctx_size,
 };
@@ -370,7 +372,7 @@ error:
 static int
 bdev_ftl_initialize(void)
 {
-	return 0;
+	return spdk_ftl_init();
 }
 
 void
@@ -384,6 +386,12 @@ bdev_ftl_delete_bdev(const char *name, spdk_bdev_unregister_cb cb_fn, void *cb_a
 	}
 }
 
+static void
+bdev_ftl_finish(void)
+{
+	spdk_ftl_fini();
+}
+
 static void
 bdev_ftl_create_defered_cb(const struct ftl_bdev_info *info, void *ctx, int status)
 {