bdev.c: encapsulate members of spdk_bdev_part.

Change-Id: Ia3d04905d319c075a12726ca85c3aa1d3135db44
Signed-off-by: Seth Howell <seth.howell@intel.com>
Reviewed-on: https://review.gerrithub.io/417176
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>

CHANGELOG.md

@@ -35,6 +35,11 @@ on each call. This allows multiple callers to query I/O statistics without confl
 with each other. Existing users will need to adjust their code to record the previous
 I/O statistics to calculate the delta between calls.
 
+A new public header file bdev_module.h has been introduced to facilitate the development
+of new bdev modules. This header includes an interface for the spdk_bdev_part and
+spdk_bdev_part_base objects to enable the creation of multiple virtual bdevs on top of a
+single base bdev.
+
 ### Env
 
 The spdk_mem_map_translate() function now takes a size parameter to indicate the size of

include/spdk/bdev_module.h

@@ -736,10 +736,24 @@ uint32_t spdk_bdev_part_base_get_ref(struct spdk_bdev_part_base *part_base);
 typedef void (*spdk_bdev_part_base_free_fn)(void *ctx);
 
 struct spdk_bdev_part {
-	struct spdk_bdev		bdev;
-	struct spdk_bdev_part_base	*base;
-	uint64_t			offset_blocks;
+	/* Entry into the module's global list of bdev parts */
 	TAILQ_ENTRY(spdk_bdev_part)	tailq;
+
+	/**
+	 * Fields that are used internally by part.c These fields should only
+	 * be accessed from a module using any pertinent get and set methods.
+	 */
+	struct bdev_part_internal_fields {
+
+		/* This part's corresponding bdev object. Not to be confused with the base bdev */
+		struct spdk_bdev		bdev;
+
+		/* The base to which this part belongs */
+		struct spdk_bdev_part_base	*base;
+
+		/* number of blocks from the start of the base bdev to the start of this part */
+		uint64_t			offset_blocks;
+	} internal;
 };
 
 struct spdk_bdev_part_channel {
@@ -830,6 +844,47 @@ int spdk_bdev_part_construct(struct spdk_bdev_part *part, struct spdk_bdev_part_
  */
 void spdk_bdev_part_submit_request(struct spdk_bdev_part_channel *ch, struct spdk_bdev_io *bdev_io);
 
+/**
+ * Return a pointer to this part's spdk_bdev.
+ *
+ * \param part An spdk_bdev_part object.
+ *
+ * \return A pointer to this part's spdk_bdev object.
+ */
+struct spdk_bdev *spdk_bdev_part_get_bdev(struct spdk_bdev_part *part);
+
+/**
+ * Return a pointer to this part's base.
+ *
+ * \param part An spdk_bdev_part object.
+ *
+ * \return A pointer to this part's spdk_bdev_part_base object.
+ */
+struct spdk_bdev_part_base *spdk_bdev_part_get_base(struct spdk_bdev_part *part);
+
+/**
+ * Return a pointer to this part's base bdev.
+ *
+ * The return value of this function is equivalent to calling
+ * spdk_bdev_part_base_get_bdev on this part's base.
+ *
+ * \param part An spdk_bdev_part object.
+ *
+ * \return A pointer to the bdev belonging to this part's base.
+ */
+struct spdk_bdev *spdk_bdev_part_get_base_bdev(struct spdk_bdev_part *part);
+
+/**
+ * Return this part's offset from the beginning of the base bdev.
+ *
+ * This function should not be called in the I/O path. Any block
+ * translations to I/O will be handled in spdk_bdev_part_submit_request.
+ *
+ * \param part An spdk_bdev_part object.
+ *
+ * \return the block offset of this part from it's underlying bdev.
+ */
+uint64_t spdk_bdev_part_get_offset_blocks(struct spdk_bdev_part *part);
 
 /*
  * Macro used to register module for later initialization.

lib/bdev/error/vbdev_error.c

@@ -113,7 +113,7 @@ spdk_vbdev_inject_error(char *name, uint32_t io_type, uint32_t error_type, uint3
 	}
 
 	TAILQ_FOREACH(part, &g_error_disks, tailq) {
-		if (bdev == &part->bdev) {
+		if (bdev == spdk_bdev_part_get_bdev(part)) {
 			error_disk = (struct error_disk *)part;
 			break;
 		}
@@ -206,7 +206,7 @@ static int
 vbdev_error_destruct(void *ctx)
 {
 	struct error_disk *error_disk = ctx;
-	struct spdk_bdev *base_bdev = spdk_bdev_part_base_get_bdev(error_disk->part.base);
+	struct spdk_bdev *base_bdev = spdk_bdev_part_get_base_bdev(&error_disk->part);
 	int rc;
 
 	rc = vbdev_error_config_remove(base_bdev->name);
@@ -221,7 +221,7 @@ static int
 vbdev_error_dump_info_json(void *ctx, struct spdk_json_write_ctx *w)
 {
 	struct error_disk *error_disk = ctx;
-	struct spdk_bdev *base_bdev = spdk_bdev_part_base_get_bdev(error_disk->part.base);
+	struct spdk_bdev *base_bdev = spdk_bdev_part_get_base_bdev(&error_disk->part);
 
 	spdk_json_write_name(w, "error_disk");
 	spdk_json_write_object_begin(w);

lib/bdev/gpt/vbdev_gpt.c

@@ -193,10 +193,12 @@ static int
 vbdev_gpt_dump_info_json(void *ctx, struct spdk_json_write_ctx *w)
 {
 	struct gpt_disk *gpt_disk = SPDK_CONTAINEROF(ctx, struct gpt_disk, part);
-	struct gpt_base *gpt_base = spdk_bdev_part_base_get_ctx(gpt_disk->part.base);
-	struct spdk_bdev *part_base_bdev = spdk_bdev_part_base_get_bdev(gpt_disk->part.base);
+	struct spdk_bdev_part_base *base_bdev = spdk_bdev_part_get_base(&gpt_disk->part);
+	struct gpt_base *gpt_base = spdk_bdev_part_base_get_ctx(base_bdev);
+	struct spdk_bdev *part_base_bdev = spdk_bdev_part_base_get_bdev(base_bdev);
 	struct spdk_gpt *gpt = &gpt_base->gpt;
 	struct spdk_gpt_partition_entry *gpt_entry = &gpt->partitions[gpt_disk->partition_index];
+	uint64_t offset_blocks = spdk_bdev_part_get_offset_blocks(&gpt_disk->part);
 
 	spdk_json_write_name(w, "gpt");
 	spdk_json_write_object_begin(w);
@@ -205,7 +207,7 @@ vbdev_gpt_dump_info_json(void *ctx, struct spdk_json_write_ctx *w)
 	spdk_json_write_string(w, spdk_bdev_get_name(part_base_bdev));
 
 	spdk_json_write_name(w, "offset_blocks");
-	spdk_json_write_uint64(w, gpt_disk->part.offset_blocks);
+	spdk_json_write_uint64(w, offset_blocks);
 
 	spdk_json_write_name(w, "partition_type_guid");
 	write_guid(w, &gpt_entry->part_type_guid);

lib/bdev/part.c

@@ -107,9 +107,9 @@ spdk_bdev_part_free_cb(void *io_device)
 	struct spdk_bdev_part_base *base;
 
 	assert(part);
-	assert(part->base);
+	assert(part->internal.base);
 
-	base = part->base;
+	base = part->internal.base;
 
 	TAILQ_REMOVE(base->tailq, part, tailq);
 
@@ -118,8 +118,8 @@ spdk_bdev_part_free_cb(void *io_device)
 		spdk_bdev_part_base_free(base);
 	}
 
-	spdk_bdev_destruct_done(&part->bdev, 0);
-	free(part->bdev.name);
+	spdk_bdev_destruct_done(&part->internal.bdev, 0);
+	free(part->internal.bdev.name);
 	free(part);
 }
 
@@ -139,8 +139,8 @@ spdk_bdev_part_base_hotremove(struct spdk_bdev *base_bdev, struct bdev_part_tail
 	struct spdk_bdev_part *part, *tmp;
 
 	TAILQ_FOREACH_SAFE(part, tailq, tailq, tmp) {
-		if (part->base->bdev == base_bdev) {
-			spdk_bdev_unregister(&part->bdev, NULL, NULL);
+		if (part->internal.base->bdev == base_bdev) {
+			spdk_bdev_unregister(&part->internal.bdev, NULL, NULL);
 		}
 	}
 }
@@ -150,7 +150,7 @@ spdk_bdev_part_io_type_supported(void *_part, enum spdk_bdev_io_type io_type)
 {
 	struct spdk_bdev_part *part = _part;
 
-	return part->base->bdev->fn_table->io_type_supported(part->base->bdev, io_type);
+	return part->internal.base->bdev->fn_table->io_type_supported(part->internal.base->bdev, io_type);
 }
 
 static struct spdk_io_channel *
@@ -161,6 +161,30 @@ spdk_bdev_part_get_io_channel(void *_part)
 	return spdk_get_io_channel(part);
 }
 
+struct spdk_bdev *
+spdk_bdev_part_get_bdev(struct spdk_bdev_part *part)
+{
+	return &part->internal.bdev;
+}
+
+struct spdk_bdev_part_base *
+spdk_bdev_part_get_base(struct spdk_bdev_part *part)
+{
+	return part->internal.base;
+}
+
+struct spdk_bdev *
+spdk_bdev_part_get_base_bdev(struct spdk_bdev_part *part)
+{
+	return part->internal.base->bdev;
+}
+
+uint64_t
+spdk_bdev_part_get_offset_blocks(struct spdk_bdev_part *part)
+{
+	return part->internal.offset_blocks;
+}
+
 static void
 spdk_bdev_part_complete_io(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
 {
@@ -176,38 +200,38 @@ spdk_bdev_part_submit_request(struct spdk_bdev_part_channel *ch, struct spdk_bde
 {
 	struct spdk_bdev_part *part = ch->part;
 	struct spdk_io_channel *base_ch = ch->base_ch;
-	struct spdk_bdev_desc *base_desc = part->base->desc;
+	struct spdk_bdev_desc *base_desc = part->internal.base->desc;
 	uint64_t offset;
 	int rc = 0;
 
 	/* Modify the I/O to adjust for the offset within the base bdev. */
 	switch (bdev_io->type) {
 	case SPDK_BDEV_IO_TYPE_READ:
-		offset = bdev_io->u.bdev.offset_blocks + part->offset_blocks;
+		offset = bdev_io->u.bdev.offset_blocks + part->internal.offset_blocks;
 		rc = spdk_bdev_readv_blocks(base_desc, base_ch, bdev_io->u.bdev.iovs,
 					    bdev_io->u.bdev.iovcnt, offset,
 					    bdev_io->u.bdev.num_blocks, spdk_bdev_part_complete_io,
 					    bdev_io);
 		break;
 	case SPDK_BDEV_IO_TYPE_WRITE:
-		offset = bdev_io->u.bdev.offset_blocks + part->offset_blocks;
+		offset = bdev_io->u.bdev.offset_blocks + part->internal.offset_blocks;
 		rc = spdk_bdev_writev_blocks(base_desc, base_ch, bdev_io->u.bdev.iovs,
 					     bdev_io->u.bdev.iovcnt, offset,
 					     bdev_io->u.bdev.num_blocks, spdk_bdev_part_complete_io,
 					     bdev_io);
 		break;
 	case SPDK_BDEV_IO_TYPE_WRITE_ZEROES:
-		offset = bdev_io->u.bdev.offset_blocks + part->offset_blocks;
+		offset = bdev_io->u.bdev.offset_blocks + part->internal.offset_blocks;
 		rc = spdk_bdev_write_zeroes_blocks(base_desc, base_ch, offset, bdev_io->u.bdev.num_blocks,
 						   spdk_bdev_part_complete_io, bdev_io);
 		break;
 	case SPDK_BDEV_IO_TYPE_UNMAP:
-		offset = bdev_io->u.bdev.offset_blocks + part->offset_blocks;
+		offset = bdev_io->u.bdev.offset_blocks + part->internal.offset_blocks;
 		rc = spdk_bdev_unmap_blocks(base_desc, base_ch, offset, bdev_io->u.bdev.num_blocks,
 					    spdk_bdev_part_complete_io, bdev_io);
 		break;
 	case SPDK_BDEV_IO_TYPE_FLUSH:
-		offset = bdev_io->u.bdev.offset_blocks + part->offset_blocks;
+		offset = bdev_io->u.bdev.offset_blocks + part->internal.offset_blocks;
 		rc = spdk_bdev_flush_blocks(base_desc, base_ch, offset, bdev_io->u.bdev.num_blocks,
 					    spdk_bdev_part_complete_io, bdev_io);
 		break;
@@ -232,13 +256,13 @@ spdk_bdev_part_channel_create_cb(void *io_device, void *ctx_buf)
 	struct spdk_bdev_part_channel *ch = ctx_buf;
 
 	ch->part = part;
-	ch->base_ch = spdk_bdev_get_io_channel(part->base->desc);
+	ch->base_ch = spdk_bdev_get_io_channel(part->internal.base->desc);
 	if (ch->base_ch == NULL) {
 		return -1;
 	}
 
-	if (part->base->ch_create_cb) {
-		return part->base->ch_create_cb(io_device, ctx_buf);
+	if (part->internal.base->ch_create_cb) {
+		return part->internal.base->ch_create_cb(io_device, ctx_buf);
 	} else {
 		return 0;
 	}
@@ -250,8 +274,8 @@ spdk_bdev_part_channel_destroy_cb(void *io_device, void *ctx_buf)
 	struct spdk_bdev_part *part = (struct spdk_bdev_part *)io_device;
 	struct spdk_bdev_part_channel *ch = ctx_buf;
 
-	if (part->base->ch_destroy_cb) {
-		part->base->ch_destroy_cb(io_device, ctx_buf);
+	if (part->internal.base->ch_destroy_cb) {
+		part->internal.base->ch_destroy_cb(io_device, ctx_buf);
 	}
 	spdk_put_io_channel(ch->base_ch);
 }
@@ -303,20 +327,20 @@ spdk_bdev_part_construct(struct spdk_bdev_part *part, struct spdk_bdev_part_base
 			 char *name, uint64_t offset_blocks, uint64_t num_blocks,
 			 char *product_name)
 {
-	part->bdev.name = name;
-	part->bdev.blocklen = base->bdev->blocklen;
-	part->bdev.blockcnt = num_blocks;
-	part->offset_blocks = offset_blocks;
+	part->internal.bdev.name = name;
+	part->internal.bdev.blocklen = base->bdev->blocklen;
+	part->internal.bdev.blockcnt = num_blocks;
+	part->internal.offset_blocks = offset_blocks;
 
-	part->bdev.write_cache = base->bdev->write_cache;
-	part->bdev.need_aligned_buffer = base->bdev->need_aligned_buffer;
-	part->bdev.product_name = product_name;
-	part->bdev.ctxt = part;
-	part->bdev.module = base->module;
-	part->bdev.fn_table = base->fn_table;
+	part->internal.bdev.write_cache = base->bdev->write_cache;
+	part->internal.bdev.need_aligned_buffer = base->bdev->need_aligned_buffer;
+	part->internal.bdev.product_name = product_name;
+	part->internal.bdev.ctxt = part;
+	part->internal.bdev.module = base->module;
+	part->internal.bdev.fn_table = base->fn_table;
 
 	__sync_fetch_and_add(&base->ref, 1);
-	part->base = base;
+	part->internal.base = base;
 
 	if (!base->claimed) {
 		int rc;
@@ -324,7 +348,7 @@ spdk_bdev_part_construct(struct spdk_bdev_part *part, struct spdk_bdev_part_base
 		rc = spdk_bdev_module_claim_bdev(base->bdev, base->desc, base->module);
 		if (rc) {
 			SPDK_ERRLOG("could not claim bdev %s\n", spdk_bdev_get_name(base->bdev));
-			free(part->bdev.name);
+			free(part->internal.bdev.name);
 			return -1;
 		}
 		base->claimed = true;
@@ -333,7 +357,7 @@ spdk_bdev_part_construct(struct spdk_bdev_part *part, struct spdk_bdev_part_base
 	spdk_io_device_register(part, spdk_bdev_part_channel_create_cb,
 				spdk_bdev_part_channel_destroy_cb,
 				base->channel_size);
-	spdk_vbdev_register(&part->bdev, &base->bdev, 1);
+	spdk_vbdev_register(&part->internal.bdev, &base->bdev, 1);
 	TAILQ_INSERT_TAIL(base->tailq, part, tailq);
 
 	return 0;

lib/bdev/split/vbdev_split.c

@@ -121,7 +121,8 @@ static int
 vbdev_split_dump_info_json(void *ctx, struct spdk_json_write_ctx *w)
 {
 	struct spdk_bdev_part *part = ctx;
-	struct spdk_bdev *split_base_bdev = spdk_bdev_part_base_get_bdev(part->base);
+	struct spdk_bdev *split_base_bdev = spdk_bdev_part_get_base_bdev(part);
+	uint64_t offset_blocks = spdk_bdev_part_get_offset_blocks(part);
 
 	spdk_json_write_name(w, "split");
 	spdk_json_write_object_begin(w);
@@ -129,7 +130,7 @@ vbdev_split_dump_info_json(void *ctx, struct spdk_json_write_ctx *w)
 	spdk_json_write_name(w, "base_bdev");
 	spdk_json_write_string(w, spdk_bdev_get_name(split_base_bdev));
 	spdk_json_write_name(w, "offset_blocks");
-	spdk_json_write_uint64(w, part->offset_blocks);
+	spdk_json_write_uint64(w, offset_blocks);
 
 	spdk_json_write_object_end(w);