update source to Ceph Pacific 16.2.2

[ceph.git] / ceph / src / spdk / include / spdk / bdev_module.h

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/** \file
 * Block Device Module Interface
 *
 * For information on how to write a bdev module, see @ref bdev_module.
 */

#ifndef SPDK_BDEV_MODULE_H
#define SPDK_BDEV_MODULE_H

#include "spdk/stdinc.h"

#include "spdk/bdev.h"
#include "spdk/bdev_zone.h"
#include "spdk/queue.h"
#include "spdk/scsi_spec.h"
#include "spdk/thread.h"
#include "spdk/util.h"
#include "spdk/uuid.h"

/** Block device module */
struct spdk_bdev_module {
        /**
         * Initialization function for the module.  Called by the spdk
         * application during startup.
         *
         * Modules are required to define this function.
         */
        int (*module_init)(void);

        /**
         * Optional callback for modules that require notification of when
         * the bdev subsystem has completed initialization.
         *
         * Modules are not required to define this function.
         */
        void (*init_complete)(void);

        /**
         * Optional callback for modules that require notification of when
         * the bdev subsystem is starting the fini process.
         *
         * Modules are not required to define this function.
         */
        void (*fini_start)(void);

        /**
         * Finish function for the module.  Called by the spdk application
         * after all bdevs for all modules have been unregistered.  This allows
         * the module to do any final cleanup before the SPDK application exits.
         *
         * Modules are not required to define this function.
         */
        void (*module_fini)(void);

        /**
         * Function called to return a text string representing the
         * module's configuration options for inclusion in a configuration file.
         */
        void (*config_text)(FILE *fp);

        /**
         * Function called to return a text string representing the module-level
         * JSON RPCs required to regenerate the current configuration.  This will
         * include module-level configuration options, or methods to construct
         * bdevs when one RPC may generate multiple bdevs (for example, an NVMe
         * controller with multiple namespaces).
         *
         * Per-bdev JSON RPCs (where one "construct" RPC always creates one bdev)
         * may be implemented here, or by the bdev's write_config_json function -
         * but not both.  Bdev module implementers may choose which mechanism to
         * use based on the module's design.
         *
         * \return 0 on success or Bdev specific negative error code.
         */
        int (*config_json)(struct spdk_json_write_ctx *w);

        /** Name for the modules being defined. */
        const char *name;

        /**
         * Returns the allocation size required for the backend for uses such as local
         * command structs, local SGL, iovecs, or other user context.
         */
        int (*get_ctx_size)(void);

        /**
         * First notification that a bdev should be examined by a virtual bdev module.
         * Virtual bdev modules may use this to examine newly-added bdevs and automatically
         * create their own vbdevs, but no I/O to device can be send to bdev at this point.
         * Only vbdevs based on config files can be created here. This callback must make
         * its decision to claim the module synchronously.
         * It must also call spdk_bdev_module_examine_done() before returning. If the module
         * needs to perform asynchronous operations such as I/O after claiming the bdev,
         * it may define an examine_disk callback.  The examine_disk callback will then
         * be called immediately after the examine_config callback returns.
         */
        void (*examine_config)(struct spdk_bdev *bdev);

        /**
         * Second notification that a bdev should be examined by a virtual bdev module.
         * Virtual bdev modules may use this to examine newly-added bdevs and automatically
         * create their own vbdevs. This callback may use I/O operations end finish asynchronously.
         */
        void (*examine_disk)(struct spdk_bdev *bdev);

        /**
         * Denotes if the module_init function may complete asynchronously. If set to true,
         * the module initialization has to be explicitly completed by calling
         * spdk_bdev_module_init_done().
         */
        bool async_init;

        /**
         * Denotes if the module_fini function may complete asynchronously.
         * If set to true finishing has to be explicitly completed by calling
         * spdk_bdev_module_fini_done().
         */
        bool async_fini;

        /**
         * Fields that are used by the internal bdev subsystem. Bdev modules
         *  must not read or write to these fields.
         */
        struct __bdev_module_internal_fields {
                /**
                 * Count of bdev inits/examinations in progress. Used by generic bdev
                 * layer and must not be modified by bdev modules.
                 *
                 * \note Used internally by bdev subsystem, don't change this value in bdev module.
                 */
                uint32_t action_in_progress;

                TAILQ_ENTRY(spdk_bdev_module) tailq;
        } internal;
};

typedef void (*spdk_bdev_unregister_cb)(void *cb_arg, int rc);

/**
 * 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)(void *ctx);

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

        /** Check if the block device supports a specific I/O type. */
        bool (*io_type_supported)(void *ctx, 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)(void *ctx);

        /**
         * Output driver-specific information to a JSON stream. Optional - may be NULL.
         *
         * The JSON write context will be initialized with an open object, so the bdev
         * driver should write a name (based on the driver name) followed by a JSON value
         * (most likely another nested object).
         */
        int (*dump_info_json)(void *ctx, struct spdk_json_write_ctx *w);

        /**
         * Output bdev-specific RPC configuration to a JSON stream. Optional - may be NULL.
         *
         * This function should only be implemented for bdevs which can be configured
         * independently of other bdevs.  For example, RPCs to create a bdev for an NVMe
         * namespace may not be generated by this function, since enumerating an NVMe
         * namespace requires attaching to an NVMe controller, and that controller may
         * contain multiple namespaces.  The spdk_bdev_module's config_json function should
         * be used instead for these cases.
         *
         * The JSON write context will be initialized with an open object, so the bdev
         * driver should write all data necessary to recreate this bdev by invoking
         * constructor method. No other data should be written.
         */
        void (*write_config_json)(struct spdk_bdev *bdev, struct spdk_json_write_ctx *w);

        /** Get spin-time per I/O channel in microseconds.
         *  Optional - may be NULL.
         */
        uint64_t (*get_spin_time)(struct spdk_io_channel *ch);
};

/** bdev I/O completion status */
enum spdk_bdev_io_status {
        SPDK_BDEV_IO_STATUS_ABORTED = -7,
        SPDK_BDEV_IO_STATUS_FIRST_FUSED_FAILED = -6,
        SPDK_BDEV_IO_STATUS_MISCOMPARE = -5,
        /*
         * NOMEM should be returned when a bdev module cannot start an I/O because of
         *  some lack of resources.  It may not be returned for RESET I/O.  I/O completed
         *  with NOMEM status will be retried after some I/O from the same channel have
         *  completed.
         */
        SPDK_BDEV_IO_STATUS_NOMEM = -4,
        SPDK_BDEV_IO_STATUS_SCSI_ERROR = -3,
        SPDK_BDEV_IO_STATUS_NVME_ERROR = -2,
        SPDK_BDEV_IO_STATUS_FAILED = -1,
        SPDK_BDEV_IO_STATUS_PENDING = 0,
        SPDK_BDEV_IO_STATUS_SUCCESS = 1,
};

struct spdk_bdev_alias {
        char *alias;
        TAILQ_ENTRY(spdk_bdev_alias) tailq;
};

typedef TAILQ_HEAD(, spdk_bdev_io) bdev_io_tailq_t;
typedef STAILQ_HEAD(, spdk_bdev_io) bdev_io_stailq_t;
typedef TAILQ_HEAD(, lba_range) lba_range_tailq_t;

struct spdk_bdev {
        /** User context passed in by the backend */
        void *ctxt;

        /** Unique name for this block device. */
        char *name;

        /** Unique aliases for this block device. */
        TAILQ_HEAD(spdk_bdev_aliases_list, spdk_bdev_alias) aliases;

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

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

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

        /** Number of blocks */
        uint64_t blockcnt;

        /** Number of blocks required for write */
        uint32_t write_unit_size;

        /** Atomic compare & write unit */
        uint16_t acwu;

        /**
         * Specifies an alignment requirement for data buffers associated with an spdk_bdev_io.
         * 0 = no alignment requirement
         * >0 = alignment requirement is 2 ^ required_alignment.
         * bdev layer will automatically double buffer any spdk_bdev_io that violates this
         * alignment, before the spdk_bdev_io is submitted to the bdev module.
         */
        uint8_t required_alignment;

        /**
         * Specifies whether the optimal_io_boundary is mandatory or
         * only advisory.  If set to true, the bdev layer will split
         * READ and WRITE I/O that span the optimal_io_boundary before
         * submitting them to the bdev module.
         *
         * Note that this field cannot be used to force splitting of
         * UNMAP, WRITE_ZEROES or FLUSH I/O.
         */
        bool split_on_optimal_io_boundary;

        /**
         * Optimal I/O boundary in blocks, or 0 for no value reported.
         */
        uint32_t optimal_io_boundary;

        /**
         * UUID for this bdev.
         *
         * Fill with zeroes if no uuid is available. The bdev layer
         * will automatically populate this if necessary.
         */
        struct spdk_uuid uuid;

        /** Size in bytes of a metadata for the backend */
        uint32_t md_len;

        /**
         * Specify metadata location and set to true if metadata is interleaved
         * with block data or false if metadata is separated with block data.
         *
         * Note that this field is valid only if there is metadata.
         */
        bool md_interleave;

        /**
         * DIF type for this bdev.
         *
         * Note that this field is valid only if there is metadata.
         */
        enum spdk_dif_type dif_type;

        /*
         * DIF location.
         *
         * Set to true if DIF is set in the first 8 bytes of metadata or false
         * if DIF is set in the last 8 bytes of metadata.
         *
         * Note that this field is valid only if DIF is enabled.
         */
        bool dif_is_head_of_md;

        /**
         * Specify whether each DIF check type is enabled.
         */
        uint32_t dif_check_flags;

        /**
         * Specify whether bdev is zoned device.
         */
        bool zoned;

        /**
         * Default size of each zone (in blocks).
         */
        uint64_t zone_size;

        /**
         * Maximum number of open zones.
         */
        uint32_t max_open_zones;

        /**
         * Optimal number of open zones.
         */
        uint32_t optimal_open_zones;

        /**
         * Specifies whether bdev supports media management events.
         */
        bool media_events;

        /**
         * Pointer to the bdev module that registered this bdev.
         */
        struct spdk_bdev_module *module;

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

        /** Fields that are used internally by the bdev subsystem.  Bdev modules
         *  must not read or write to these fields.
         */
        struct __bdev_internal_fields {
                /** Quality of service parameters */
                struct spdk_bdev_qos *qos;

                /** True if the state of the QoS is being modified */
                bool qos_mod_in_progress;

                /** Mutex protecting claimed */
                pthread_mutex_t mutex;

                /** The bdev status */
                enum spdk_bdev_status status;

                /**
                 * Pointer to the module that has claimed this bdev for purposes of creating virtual
                 *  bdevs on top of it.  Set to NULL if the bdev has not been claimed.
                 */
                struct spdk_bdev_module *claim_module;

                /** Callback function that will be called after bdev destruct is completed. */
                spdk_bdev_unregister_cb unregister_cb;

                /** Unregister call context */
                void *unregister_ctx;

                /** List of open descriptors for this block device. */
                TAILQ_HEAD(, spdk_bdev_desc) open_descs;

                TAILQ_ENTRY(spdk_bdev) link;

                /** points to a reset bdev_io if one is in progress. */
                struct spdk_bdev_io *reset_in_progress;

                /** poller for tracking the queue_depth of a device, NULL if not tracking */
                struct spdk_poller *qd_poller;

                /** period at which we poll for queue depth information */
                uint64_t period;

                /** used to aggregate queue depth while iterating across the bdev's open channels */
                uint64_t temporary_queue_depth;

                /** queue depth as calculated the last time the telemetry poller checked. */
                uint64_t measured_queue_depth;

                /** most recent value of ticks spent performing I/O. Used to calculate the weighted time doing I/O */
                uint64_t io_time;

                /** weighted time performing I/O. Equal to measured_queue_depth * period */
                uint64_t weighted_io_time;

                /** accumulated I/O statistics for previously deleted channels of this bdev */
                struct spdk_bdev_io_stat stat;

                /** histogram enabled on this bdev */
                bool    histogram_enabled;
                bool    histogram_in_progress;

                /** Currently locked ranges for this bdev.  Used to populate new channels. */
                lba_range_tailq_t locked_ranges;

                /** Pending locked ranges for this bdev.  These ranges are not currently
                 *  locked due to overlapping with another locked range.
                 */
                lba_range_tailq_t pending_locked_ranges;
        } internal;
};

/**
 * Callback when buffer is allocated for the bdev I/O.
 *
 * \param ch The I/O channel the bdev I/O was handled on.
 * \param bdev_io The bdev I/O
 * \param success True if buffer is allocated successfully or the bdev I/O has an SGL
 * assigned already, or false if it failed. The possible reason of failure is the size
 * of the buffer to allocate is greater than the permitted maximum.
 */
typedef void (*spdk_bdev_io_get_buf_cb)(struct spdk_io_channel *ch, struct spdk_bdev_io *bdev_io,
                                        bool success);

/**
 * Callback when an auxiliary buffer is allocated for the bdev I/O.
 *
 * \param ch The I/O channel the bdev I/O was handled on.
 * \param bdev_io The bdev I/O
 * \param aux_buf Pointer to the allocated buffer.  NULL if there was a failuer such as
 * the size of the buffer to allocate is greater than the permitted maximum.
 */
typedef void (*spdk_bdev_io_get_aux_buf_cb)(struct spdk_io_channel *ch,
                struct spdk_bdev_io *bdev_io, void *aux_buf);

#define BDEV_IO_NUM_CHILD_IOV 32

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

        /** Enumerated value representing the I/O type. */
        uint8_t type;

        /** Number of IO submission retries */
        uint16_t num_retries;

        /** A single iovec element for use by this bdev_io. */
        struct iovec iov;

        /** Array of iovecs used for I/O splitting. */
        struct iovec child_iov[BDEV_IO_NUM_CHILD_IOV];

        union {
                struct {
                        /** 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 fused operations such as COMPARE_AND_WRITE, array of iovecs
                         *  for the second operation.
                         */
                        struct iovec *fused_iovs;

                        /** Number of iovecs in fused_iovs. */
                        int fused_iovcnt;

                        /* Metadata buffer */
                        void *md_buf;

                        /** Total size of data to be transferred. */
                        uint64_t num_blocks;

                        /** Starting offset (in blocks) of the bdev for this I/O. */
                        uint64_t offset_blocks;

                        /** stored user callback in case we split the I/O and use a temporary callback */
                        spdk_bdev_io_completion_cb stored_user_cb;

                        /** number of blocks remaining in a split i/o */
                        uint64_t split_remaining_num_blocks;

                        /** current offset of the split I/O in the bdev */
                        uint64_t split_current_offset_blocks;

                        /** count of outstanding batched split I/Os */
                        uint32_t split_outstanding;

                        struct {
                                /** Whether the buffer should be populated with the real data */
                                uint8_t populate : 1;

                                /** Whether the buffer should be committed back to disk */
                                uint8_t commit : 1;

                                /** True if this request is in the 'start' phase of zcopy. False if in 'end'. */
                                uint8_t start : 1;
                        } zcopy;

                        struct {
                                /** The callback argument for the outstanding request which this abort
                                 *  attempts to cancel.
                                 */
                                void *bio_cb_arg;
                        } abort;
                } bdev;
                struct {
                        /** Channel reference held while messages for this reset are in progress. */
                        struct spdk_io_channel *ch_ref;
                } reset;
                struct {
                        /** The outstanding request matching bio_cb_arg which this abort attempts to cancel. */
                        struct spdk_bdev_io *bio_to_abort;
                } abort;
                struct {
                        /* The NVMe command to execute */
                        struct spdk_nvme_cmd cmd;

                        /* The data buffer to transfer */
                        void *buf;

                        /* The number of bytes to transfer */
                        size_t nbytes;

                        /* The meta data buffer to transfer */
                        void *md_buf;

                        /* meta data buffer size to transfer */
                        size_t md_len;
                } nvme_passthru;
                struct {
                        /* First logical block of a zone */
                        uint64_t zone_id;

                        /* Number of zones */
                        uint32_t num_zones;

                        /* Used to change zoned device zone state */
                        enum spdk_bdev_zone_action zone_action;

                        /* The data buffer */
                        void *buf;
                } zone_mgmt;
        } u;

        /** It may be used by modules to put the bdev_io into its own list. */
        TAILQ_ENTRY(spdk_bdev_io) module_link;

        /**
         *  Fields that are used internally by the bdev subsystem.  Bdev modules
         *  must not read or write to these fields.
         */
        struct __bdev_io_internal_fields {
                /** The bdev I/O channel that this was handled on. */
                struct spdk_bdev_channel *ch;

                /** The bdev I/O channel that this was submitted on. */
                struct spdk_bdev_channel *io_submit_ch;

                /** The bdev descriptor that was used when submitting this I/O. */
                struct spdk_bdev_desc *desc;

                /** 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;

                /** Current tsc at submit time. Used to calculate latency at completion. */
                uint64_t submit_tsc;

                /** Error information from a device */
                union {
                        struct {
                                /** NVMe completion queue entry DW0 */
                                uint32_t cdw0;
                                /** NVMe status code type */
                                uint8_t sct;
                                /** NVMe status code */
                                uint8_t sc;
                        } nvme;
                        /** Only valid when status is SPDK_BDEV_IO_STATUS_SCSI_ERROR */
                        struct {
                                /** SCSI status code */
                                uint8_t sc;
                                /** SCSI sense key */
                                uint8_t sk;
                                /** SCSI additional sense code */
                                uint8_t asc;
                                /** SCSI additional sense code qualifier */
                                uint8_t ascq;
                        } scsi;
                } error;

                /**
                 * Set to true while the bdev module submit_request function is in progress.
                 *
                 * This is used to decide whether spdk_bdev_io_complete() can complete the I/O directly
                 * or if completion must be deferred via an event.
                 */
                bool in_submit_request;

                /** Status for the IO */
                int8_t status;

                /** bdev allocated memory associated with this request */
                void *buf;

                /** requested size of the buffer associated with this I/O */
                uint64_t buf_len;

                /** if the request is double buffered, store original request iovs here */
                struct iovec  bounce_iov;
                struct iovec *orig_iovs;
                int           orig_iovcnt;
                void         *orig_md_buf;

                /** Callback for when the aux buf is allocated */
                spdk_bdev_io_get_aux_buf_cb get_aux_buf_cb;

                /** Callback for when buf is allocated */
                spdk_bdev_io_get_buf_cb get_buf_cb;

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

                /** Entry to the list need_buf of struct spdk_bdev. */
                STAILQ_ENTRY(spdk_bdev_io) buf_link;

                /** Entry to the list io_submitted of struct spdk_bdev_channel */
                TAILQ_ENTRY(spdk_bdev_io) ch_link;

                /** Enables queuing parent I/O when no bdev_ios available for split children. */
                struct spdk_bdev_io_wait_entry waitq_entry;
        } internal;

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

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

/**
 * Register a new bdev.
 *
 * \param bdev Block device to register.
 *
 * \return 0 on success.
 * \return -EINVAL if the bdev name is NULL.
 * \return -EEXIST if a bdev or bdev alias with the same name already exists.
 */
int spdk_bdev_register(struct spdk_bdev *bdev);

/**
 * Start unregistering a bdev. This will notify each currently open descriptor
 * on this bdev about the hotremoval in hopes that the upper layers will stop
 * using this bdev and manually close all the descriptors with spdk_bdev_close().
 * The actual bdev unregistration may be deferred until all descriptors are closed.
 *
 * \param bdev Block device to unregister.
 * \param cb_fn Callback function to be called when the unregister is complete.
 * \param cb_arg Argument to be supplied to cb_fn
 */
void spdk_bdev_unregister(struct spdk_bdev *bdev, spdk_bdev_unregister_cb cb_fn, void *cb_arg);

/**
 * Invokes the unregister callback of a bdev backing a virtual bdev.
 *
 * A Bdev with an asynchronous destruct path should return 1 from its
 * destruct function and call this function at the conclusion of that path.
 * Bdevs with synchronous destruct paths should return 0 from their destruct
 * path.
 *
 * \param bdev Block device that was destroyed.
 * \param bdeverrno Error code returned from bdev's destruct callback.
 */
void spdk_bdev_destruct_done(struct spdk_bdev *bdev, int bdeverrno);

/**
 * Register a virtual bdev.
 *
 * This function is deprecated.  Users should call spdk_bdev_register instead.
 * The bdev layer currently makes no use of the base_bdevs array, so switching
 * to spdk_bdev_register results in no loss of functionality.
 *
 * \param vbdev Virtual bdev to register.
 * \param base_bdevs Array of bdevs upon which this vbdev is based.
 * \param base_bdev_count Number of bdevs in base_bdevs.
 *
 * \return 0 on success
 * \return -EINVAL if the bdev name is NULL.
 * \return -EEXIST if the bdev already exists.
 * \return -ENOMEM if allocation of the base_bdevs array or the base bdevs vbdevs array fails.
 */
int spdk_vbdev_register(struct spdk_bdev *vbdev, struct spdk_bdev **base_bdevs,
                        int base_bdev_count);

/**
 * Indicate to the bdev layer that the module is done examining a bdev.
 *
 * To be called synchronously or asynchronously in response to the
 * module's examine function being called.
 *
 * \param module Pointer to the module completing the examination.
 */
void spdk_bdev_module_examine_done(struct spdk_bdev_module *module);

/**
 * Indicate to the bdev layer that the module is done initializing.
 *
 * To be called synchronously or asynchronously in response to the
 * module_init function being called.
 *
 * \param module Pointer to the module completing the initialization.
 */
void spdk_bdev_module_init_done(struct spdk_bdev_module *module);

/**
 * Indicate to the bdev layer that the module is done cleaning up.
 *
 * To be called either synchronously or asynchronously
 * in response to the module_fini function being called.
 *
 */
void spdk_bdev_module_finish_done(void);

/**
 * Called by a bdev module to lay exclusive write claim to a bdev.
 *
 * Also upgrades that bdev's descriptor to have write access.
 *
 * \param bdev Block device to be claimed.
 * \param desc Descriptor for the above block device.
 * \param module Bdev module attempting to claim bdev.
 *
 * \return 0 on success
 * \return -EPERM if the bdev is already claimed by another module.
 */
int spdk_bdev_module_claim_bdev(struct spdk_bdev *bdev, struct spdk_bdev_desc *desc,
                                struct spdk_bdev_module *module);

/**
 * Called to release a write claim on a block device.
 *
 * \param bdev Block device to be released.
 */
void spdk_bdev_module_release_bdev(struct spdk_bdev *bdev);

/**
 * Add alias to block device names list.
 * Aliases can be add only to registered bdev.
 *
 * \param bdev Block device to query.
 * \param alias Alias to be added to list.
 *
 * \return 0 on success
 * \return -EEXIST if alias already exists as name or alias on any bdev
 * \return -ENOMEM if memory cannot be allocated to store alias
 * \return -EINVAL if passed alias is empty
 */
int spdk_bdev_alias_add(struct spdk_bdev *bdev, const char *alias);

/**
 * Removes name from block device names list.
 *
 * \param bdev Block device to query.
 * \param alias Alias to be deleted from list.
 * \return 0 on success
 * \return -ENOENT if alias does not exists
 */
int spdk_bdev_alias_del(struct spdk_bdev *bdev, const char *alias);

/**
 * Removes all alias from block device alias list.
 *
 * \param bdev Block device to operate.
 */
void spdk_bdev_alias_del_all(struct spdk_bdev *bdev);

/**
 * Get pointer to block device aliases list.
 *
 * \param bdev Block device to query.
 * \return Pointer to bdev aliases list.
 */
const struct spdk_bdev_aliases_list *spdk_bdev_get_aliases(const struct spdk_bdev *bdev);

/**
 * Allocate a buffer for given bdev_io.  Allocation will happen
 * only if the bdev_io has no assigned SGL yet or SGL is not
 * aligned to \c bdev->required_alignment.  If SGL is not aligned,
 * this call will cause copy from SGL to bounce buffer on write
 * path or copy from bounce buffer to SGL before completion
 * callback on read path.  The buffer will be freed automatically
 * on \c spdk_bdev_free_io() call. This call will never fail.
 * In case of lack of memory given callback \c cb will be deferred
 * until enough memory is freed.
 *
 * \param bdev_io I/O to allocate buffer for.
 * \param cb callback to be called when the buffer is allocated
 * or the bdev_io has an SGL assigned already.
 * \param len size of the buffer to allocate. In case the bdev_io
 * doesn't have an SGL assigned this field must be no bigger than
 * \c SPDK_BDEV_LARGE_BUF_MAX_SIZE.
 */
void spdk_bdev_io_get_buf(struct spdk_bdev_io *bdev_io, spdk_bdev_io_get_buf_cb cb, uint64_t len);

/**
 * Allocate an auxillary buffer for given bdev_io. The length of the
 * buffer will be the same size as the bdev_io primary buffer. The buffer
 * must be freed using \c spdk_bdev_io_put_aux_buf() before completing
 * the associated bdev_io.  This call will never fail. In case of lack of
 * memory given callback \c cb will be deferred until enough memory is freed.
 *
 * \param bdev_io I/O to allocate buffer for.
 * \param cb callback to be called when the buffer is allocated
 */
void spdk_bdev_io_get_aux_buf(struct spdk_bdev_io *bdev_io, spdk_bdev_io_get_aux_buf_cb cb);

/**
 * Free an auxiliary buffer previously allocated by \c spdk_bdev_io_get_aux_buf().
 *
 * \param bdev_io bdev_io specified when the aux_buf was allocated.
 * \param aux_buf auxiliary buffer to free
 */
void spdk_bdev_io_put_aux_buf(struct spdk_bdev_io *bdev_io, void *aux_buf);

/**
 * Set the given buffer as the data buffer described by this bdev_io.
 *
 * The portion of the buffer used may be adjusted for memory alignement
 * purposes.
 *
 * \param bdev_io I/O to set the buffer on.
 * \param buf The buffer to set as the active data buffer.
 * \param len The length of the buffer.
 *
 */
void spdk_bdev_io_set_buf(struct spdk_bdev_io *bdev_io, void *buf, size_t len);

/**
 * Set the given buffer as metadata buffer described by this bdev_io.
 *
 * \param bdev_io I/O to set the buffer on.
 * \param md_buf The buffer to set as the active metadata buffer.
 * \param len The length of the metadata buffer.
 */
void spdk_bdev_io_set_md_buf(struct spdk_bdev_io *bdev_io, void *md_buf, size_t len);

/**
 * Complete a bdev_io
 *
 * \param bdev_io I/O to complete.
 * \param status The I/O completion status.
 */
void spdk_bdev_io_complete(struct spdk_bdev_io *bdev_io,
                           enum spdk_bdev_io_status status);

/**
 * Complete a bdev_io with an NVMe status code and DW0 completion queue entry
 *
 * \param bdev_io I/O to complete.
 * \param cdw0 NVMe Completion Queue DW0 value (set to 0 if not applicable)
 * \param sct NVMe Status Code Type.
 * \param sc NVMe Status Code.
 */
void spdk_bdev_io_complete_nvme_status(struct spdk_bdev_io *bdev_io, uint32_t cdw0, int sct,
                                       int sc);

/**
 * Complete a bdev_io with a SCSI status code.
 *
 * \param bdev_io I/O to complete.
 * \param sc SCSI Status Code.
 * \param sk SCSI Sense Key.
 * \param asc SCSI Additional Sense Code.
 * \param ascq SCSI Additional Sense Code Qualifier.
 */
void spdk_bdev_io_complete_scsi_status(struct spdk_bdev_io *bdev_io, enum spdk_scsi_status sc,
                                       enum spdk_scsi_sense sk, uint8_t asc, uint8_t ascq);

/**
 * Get a thread that given bdev_io was submitted on.
 *
 * \param bdev_io I/O
 * \return thread that submitted the I/O
 */
struct spdk_thread *spdk_bdev_io_get_thread(struct spdk_bdev_io *bdev_io);

/**
 * Get the bdev module's I/O channel that the given bdev_io was submitted on.
 *
 * \param bdev_io I/O
 * \return the bdev module's I/O channel that the given bdev_io was submitted on.
 */
struct spdk_io_channel *spdk_bdev_io_get_io_channel(struct spdk_bdev_io *bdev_io);

/**
 * Resize for a bdev.
 *
 * Change number of blocks for provided block device.
 * It can only be called on a registered bdev.
 *
 * \param bdev Block device to change.
 * \param size New size of bdev.
 * \return 0 on success, negated errno on failure.
 */
int spdk_bdev_notify_blockcnt_change(struct spdk_bdev *bdev, uint64_t size);

/**
 * Translates NVMe status codes to SCSI status information.
 *
 * The codes are stored in the user supplied integers.
 *
 * \param bdev_io I/O containing status codes to translate.
 * \param sc SCSI Status Code will be stored here.
 * \param sk SCSI Sense Key will be stored here.
 * \param asc SCSI Additional Sense Code will be stored here.
 * \param ascq SCSI Additional Sense Code Qualifier will be stored here.
 */
void spdk_scsi_nvme_translate(const struct spdk_bdev_io *bdev_io,
                              int *sc, int *sk, int *asc, int *ascq);

/**
 * Add the given module to the list of registered modules.
 * This function should be invoked by referencing the macro
 * SPDK_BDEV_MODULE_REGISTER in the module c file.
 *
 * \param bdev_module Module to be added.
 */
void spdk_bdev_module_list_add(struct spdk_bdev_module *bdev_module);

/**
 * Find registered module with name pointed by \c name.
 *
 * \param name name of module to be searched for.
 * \return pointer to module or NULL if no module with \c name exist
 */
struct spdk_bdev_module *spdk_bdev_module_list_find(const char *name);

static inline struct spdk_bdev_io *
spdk_bdev_io_from_ctx(void *ctx)
{
        return SPDK_CONTAINEROF(ctx, struct spdk_bdev_io, driver_ctx);
}

struct spdk_bdev_part_base;

/**
 * Returns a pointer to the spdk_bdev associated with an spdk_bdev_part_base
 *
 * \param part_base A pointer to an spdk_bdev_part_base object.
 *
 * \return A pointer to the base's spdk_bdev struct.
 */
struct spdk_bdev *spdk_bdev_part_base_get_bdev(struct spdk_bdev_part_base *part_base);

/**
 * Returns a spdk_bdev name of the corresponding spdk_bdev_part_base
 *
 * \param part_base A pointer to an spdk_bdev_part_base object.
 *
 * \return A text string representing the name of the base bdev.
 */
const char *spdk_bdev_part_base_get_bdev_name(struct spdk_bdev_part_base *part_base);

/**
 * Returns a pointer to the spdk_bdev_descriptor associated with an spdk_bdev_part_base
 *
 * \param part_base A pointer to an spdk_bdev_part_base object.
 *
 * \return A pointer to the base's spdk_bdev_desc struct.
 */
struct spdk_bdev_desc *spdk_bdev_part_base_get_desc(struct spdk_bdev_part_base *part_base);

/**
 * Returns a pointer to the tailq associated with an spdk_bdev_part_base
 *
 * \param part_base A pointer to an spdk_bdev_part_base object.
 *
 * \return The head of a tailq of spdk_bdev_part structs registered to the base's module.
 */
struct bdev_part_tailq *spdk_bdev_part_base_get_tailq(struct spdk_bdev_part_base *part_base);

/**
 * Returns a pointer to the module level context associated with an spdk_bdev_part_base
 *
 * \param part_base A pointer to an spdk_bdev_part_base object.
 *
 * \return A pointer to the module level context registered with the base in spdk_bdev_part_base_construct.
 */
void *spdk_bdev_part_base_get_ctx(struct spdk_bdev_part_base *part_base);

typedef void (*spdk_bdev_part_base_free_fn)(void *ctx);

struct spdk_bdev_part {
        /* 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 {
        struct spdk_bdev_part           *part;
        struct spdk_io_channel          *base_ch;
};

typedef TAILQ_HEAD(bdev_part_tailq, spdk_bdev_part)     SPDK_BDEV_PART_TAILQ;

/**
 * Free the base corresponding to one or more spdk_bdev_part.
 *
 * \param base The base to free.
 */
void spdk_bdev_part_base_free(struct spdk_bdev_part_base *base);

/**
 * Free an spdk_bdev_part context.
 *
 * \param part The part to free.
 *
 * \return 1 always. To indicate that the operation is asynchronous.
 */
int spdk_bdev_part_free(struct spdk_bdev_part *part);

/**
 * Calls spdk_bdev_unregister on the bdev for each part associated with base_bdev.
 *
 * \param part_base The part base object built on top of an spdk_bdev
 * \param tailq The list of spdk_bdev_part bdevs associated with this base bdev.
 */
void spdk_bdev_part_base_hotremove(struct spdk_bdev_part_base *part_base,
                                   struct bdev_part_tailq *tailq);

/**
 * Construct a new spdk_bdev_part_base on top of the provided bdev.
 *
 * \param bdev The spdk_bdev upon which this base will be built.
 * \param remove_cb Function to be called upon hotremove of the bdev.
 * \param module The module to which this bdev base belongs.
 * \param fn_table Function table for communicating with the bdev backend.
 * \param tailq The head of the list of all spdk_bdev_part structures registered to this base's module.
 * \param free_fn User provided function to free base related context upon bdev removal or shutdown.
 * \param ctx Module specific context for this bdev part base.
 * \param channel_size Channel size in bytes.
 * \param ch_create_cb Called after a new channel is allocated.
 * \param ch_destroy_cb Called upon channel deletion.
 *
 * \return 0 on success
 * \return -1 if the underlying bdev cannot be opened.
 */
struct spdk_bdev_part_base *spdk_bdev_part_base_construct(struct spdk_bdev *bdev,
                spdk_bdev_remove_cb_t remove_cb,
                struct spdk_bdev_module *module,
                struct spdk_bdev_fn_table *fn_table,
                struct bdev_part_tailq *tailq,
                spdk_bdev_part_base_free_fn free_fn,
                void *ctx,
                uint32_t channel_size,
                spdk_io_channel_create_cb ch_create_cb,
                spdk_io_channel_destroy_cb ch_destroy_cb);

/**
 * Create a logical spdk_bdev_part on top of a base.
 *
 * \param part The part object allocated by the user.
 * \param base The base from which to create the part.
 * \param name The name of the new spdk_bdev_part.
 * \param offset_blocks The offset into the base bdev at which this part begins.
 * \param num_blocks The number of blocks that this part will span.
 * \param product_name Unique name for this type of block device.
 *
 * \return 0 on success.
 * \return -1 if the bases underlying bdev cannot be claimed by the current module.
 */
int spdk_bdev_part_construct(struct spdk_bdev_part *part, struct spdk_bdev_part_base *base,
                             char *name, uint64_t offset_blocks, uint64_t num_blocks,
                             char *product_name);

/**
 * Forwards I/O from an spdk_bdev_part to the underlying base bdev.
 *
 * This function will apply the offset_blocks the user provided to
 * spdk_bdev_part_construct to the I/O. The user should not manually
 * apply this offset before submitting any I/O through this function.
 *
 * \param ch The I/O channel associated with the spdk_bdev_part.
 * \param bdev_io The I/O to be submitted to the underlying bdev.
 * \return 0 on success or non-zero if submit request failed.
 */
int 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);

/**
 * Push media management events.  To send the notification that new events are
 * available, spdk_bdev_notify_media_management needs to be called.
 *
 * \param bdev Block device
 * \param events Array of media events
 * \param num_events Size of the events array
 *
 * \return number of events pushed or negative errno in case of failure
 */
int spdk_bdev_push_media_events(struct spdk_bdev *bdev, const struct spdk_bdev_media_event *events,
                                size_t num_events);

/**
 * Send SPDK_BDEV_EVENT_MEDIA_MANAGEMENT to all open descriptors that have
 * pending media events.
 *
 * \param bdev Block device
 */
void spdk_bdev_notify_media_management(struct spdk_bdev *bdev);

/*
 *  Macro used to register module for later initialization.
 */
#define SPDK_BDEV_MODULE_REGISTER(name, module) \
static void __attribute__((constructor)) _spdk_bdev_module_register_##name(void) \
{ \
        spdk_bdev_module_list_add(module); \
} \

#endif /* SPDK_BDEV_MODULE_H */