numam-spdk/include/spdk/bdev.h

/*-
 *   BSD LICENSE
 *
 *   Copyright (C) 2008-2012 Daisuke Aoyama <aoyama@peach.ne.jp>.
 *   Copyright (c) Intel Corporation.
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** \file
 * Block device abstraction layer
 */

#ifndef SPDK_BDEV_H_
#define SPDK_BDEV_H_

#include <inttypes.h>
#include <stddef.h>  /* for offsetof */
#include <sys/uio.h> /* for struct iovec */
#include <stdbool.h>

#include "spdk/event.h"
#include "spdk/queue.h"
#include "spdk/scsi_spec.h"

#define SPDK_BDEV_SMALL_RBUF_MAX_SIZE 8192
#define SPDK_BDEV_LARGE_RBUF_MAX_SIZE (64 * 1024)

#define SPDK_BDEV_MAX_NAME_LENGTH		16
#define SPDK_BDEV_MAX_PRODUCT_NAME_LENGTH	50

struct spdk_bdev_io;

/**
 * \brief SPDK block device.
 *
 * This is a virtual representation of a block device that is exported by the backend.
 */
struct spdk_bdev {
	/** User context passed in by the backend */
	void *ctxt;

	/** Unique name for this block device. */
	char name[SPDK_BDEV_MAX_NAME_LENGTH];

	/** Unique product name for this kind of block device. */
	char product_name[SPDK_BDEV_MAX_PRODUCT_NAME_LENGTH];

	/** Size in bytes of a logical block for the backend */
	uint32_t blocklen;

	/** Number of blocks */
	uint64_t blockcnt;

	/** write cache enabled, not used at the moment */
	int write_cache;

	/**
	 * This is used to make sure buffers are sector aligned.
	 * This causes double buffering on writes.
	 */
	int need_aligned_buffer;

	/** thin provisioning, not used at the moment */
	int thin_provisioning;

	/** function table for all LUN ops */
	const struct spdk_bdev_fn_table *fn_table;

	/** Represents maximum unmap block descriptor count */
	uint32_t max_unmap_bdesc_count;

	/** generation value used by block device reset */
	uint32_t gencnt;

	/** Whether the poller is registered with the reactor */
	bool is_running;

	/** Which lcore the poller is running on */
	uint32_t lcore;

	/** Poller to submit IO and check completion */
	struct spdk_poller *poller;

	/** True if another blockdev or a LUN is using this device */
	bool claimed;

	TAILQ_ENTRY(spdk_bdev) link;
};

/** Blockdev I/O type */
enum spdk_bdev_io_type {
	SPDK_BDEV_IO_TYPE_INVALID,
	SPDK_BDEV_IO_TYPE_READ,
	SPDK_BDEV_IO_TYPE_WRITE,
	SPDK_BDEV_IO_TYPE_UNMAP,
	SPDK_BDEV_IO_TYPE_FLUSH,
	SPDK_BDEV_IO_TYPE_RESET,
};

/**
 * Function table for a block device backend.
 *
 * The backend block device function table provides a set of APIs to allow
 * communication with a backend. The main commands are read/write API
 * calls for I/O via submit_request.
 */
struct spdk_bdev_fn_table {
	/** Destroy the backend block device object */
	int (*destruct)(struct spdk_bdev *bdev);

	/**
	 * Poll the backend for I/O waiting to be completed.
	 *
	 * Optional; if the bdev does not have any periodic work to do, this pointer can be NULL.
	 */
	int (*check_io)(struct spdk_bdev *bdev);

	/** Process the IO. */
	void (*submit_request)(struct spdk_bdev_io *);

	/** Check if the block device supports a specific I/O type. */
	bool (*io_type_supported)(struct spdk_bdev *bdev, enum spdk_bdev_io_type);

	/** Get an I/O channel for the specific bdev for the calling thread. */
	struct spdk_io_channel *(*get_io_channel)(struct spdk_bdev *bdev, uint32_t priority);
};

/** Blockdev I/O completion status */
enum spdk_bdev_io_status {
	SPDK_BDEV_IO_STATUS_FAILED = -1,
	SPDK_BDEV_IO_STATUS_PENDING = 0,
	SPDK_BDEV_IO_STATUS_SUCCESS = 1,
};

/** Blockdev reset operation type */
enum spdk_bdev_reset_type {
	/**
	 * A hard reset indicates that the blockdev layer should not
	 *  invoke the completion callback for I/Os issued before the
	 *  reset is issued but completed after the reset is complete.
	 */
	SPDK_BDEV_RESET_HARD,

	/**
	 * A soft reset indicates that the blockdev layer should still
	 *  invoke the completion callback for I/Os issued before the
	 *  reset is issued but completed after the reset is complete.
	 */
	SPDK_BDEV_RESET_SOFT,
};

typedef spdk_event_fn spdk_bdev_io_completion_cb;
typedef void (*spdk_bdev_io_get_rbuf_cb)(struct spdk_bdev_io *bdev_io);

/**
 * Block device I/O
 *
 * This is an I/O that is passed to an spdk_bdev.
 */
struct spdk_bdev_io {
	/** Pointer to scratch area reserved for use by the driver consuming this spdk_bdev_io. */
	void *ctx;

	/** Generation value for each I/O. */
	uint32_t gencnt;

	/** The block device that this I/O belongs to. */
	struct spdk_bdev *bdev;

	/** Enumerated value representing the I/O type. */
	enum spdk_bdev_io_type type;

	union {
		struct {

			/** The unaligned rbuf originally allocated. */
			void *buf_unaligned;

			/** For single buffer cases, pointer to the aligned data buffer.  */
			void *buf;

			/** For single buffer cases, size of the data buffer. */
			uint64_t nbytes;

			/** Starting offset (in bytes) of the blockdev for this I/O. */
			uint64_t offset;

			/** Indicate whether the blockdev layer to put rbuf or not. */
			bool put_rbuf;
		} read;
		struct {
			/** For basic write case, use our own iovec element */
			struct iovec iov;

			/** For SG buffer cases, array of iovecs to transfer. */
			struct iovec *iovs;

			/** For SG buffer cases, number of iovecs in iovec array. */
			int iovcnt;

			/** For SG buffer cases, total size of data to be transferred. */
			size_t len;

			/** Starting offset (in bytes) of the blockdev for this I/O. */
			uint64_t offset;
		} write;
		struct {
			/** Represents the unmap block descriptors. */
			struct spdk_scsi_unmap_bdesc *unmap_bdesc;

			/** Count of unmap block descriptors. */
			uint16_t bdesc_count;
		} unmap;
		struct {
			/** Represents starting offset in bytes of the range to be flushed. */
			uint64_t offset;

			/** Represents the number of bytes to be flushed, starting at offset. */
			uint64_t length;
		} flush;
		struct {
			enum spdk_bdev_reset_type type;
		} reset;
	} u;

	/** User function that will be called when this completes */
	spdk_bdev_io_completion_cb cb;

	/** Context that will be passed to the completion callback */
	void *caller_ctx;

	struct spdk_event *cb_event;

	/** Callback for when rbuf is allocated */
	spdk_bdev_io_get_rbuf_cb get_rbuf_cb;

	/** Status for the IO */
	enum spdk_bdev_io_status status;

	/** Used in virtual device (e.g., RAID), indicates its parent spdk_bdev_io **/
	struct spdk_bdev_io *parent;

	/** Used in virtual device (e.g., RAID) for storing multiple child device I/Os **/
	TAILQ_HEAD(child_io, spdk_bdev_io) child_io;

	/** Member used for linking child I/Os together. */
	TAILQ_ENTRY(spdk_bdev_io) link;

	/** Entry to the list need_buf of struct spdk_bdev. */
	TAILQ_ENTRY(spdk_bdev_io) rbuf_link;

	/** Per I/O context for use by the blockdev module */
	uint8_t driver_ctx[0];

	/* No members may be added after driver_ctx! */
};

struct spdk_bdev *spdk_bdev_get_by_name(const char *bdev_name);
void spdk_bdev_unregister(struct spdk_bdev *bdev);

struct spdk_bdev *spdk_bdev_first(void);
struct spdk_bdev *spdk_bdev_next(struct spdk_bdev *prev);

bool spdk_bdev_io_type_supported(struct spdk_bdev *bdev, enum spdk_bdev_io_type io_type);

struct spdk_bdev_io *spdk_bdev_read(struct spdk_bdev *bdev,
				    void *buf, uint64_t offset, uint64_t nbytes,
				    spdk_bdev_io_completion_cb cb, void *cb_arg);
struct spdk_bdev_io *spdk_bdev_write(struct spdk_bdev *bdev,
				     void *buf, uint64_t offset, uint64_t nbytes,
				     spdk_bdev_io_completion_cb cb, void *cb_arg);
struct spdk_bdev_io *spdk_bdev_writev(struct spdk_bdev *bdev,
				      struct iovec *iov, int iovcnt,
				      uint64_t offset, uint64_t len,
				      spdk_bdev_io_completion_cb cb, void *cb_arg);
struct spdk_bdev_io *spdk_bdev_unmap(struct spdk_bdev *bdev,
				     struct spdk_scsi_unmap_bdesc *unmap_d,
				     uint16_t bdesc_count,
				     spdk_bdev_io_completion_cb cb, void *cb_arg);
struct spdk_bdev_io *spdk_bdev_flush(struct spdk_bdev *bdev,
				     uint64_t offset, uint64_t length,
				     spdk_bdev_io_completion_cb cb, void *cb_arg);
int spdk_bdev_io_submit(struct spdk_bdev_io *bdev_io);
void spdk_bdev_do_work(void *ctx);
int spdk_bdev_free_io(struct spdk_bdev_io *bdev_io);
int spdk_bdev_reset(struct spdk_bdev *bdev, enum spdk_bdev_reset_type,
		    spdk_bdev_io_completion_cb cb, void *cb_arg);
struct spdk_io_channel *spdk_bdev_get_io_channel(struct spdk_bdev *bdev, uint32_t priority);
#endif /* SPDK_BDEV_H_ */