/*- * BSD LICENSE * * Copyright (C) 2008-2012 Daisuke Aoyama . * 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 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /** \file * Block Device Module Interface */ #ifndef SPDK_INTERNAL_BDEV_H #define SPDK_INTERNAL_BDEV_H #include #include #include /* for offsetof */ #include /* for struct iovec */ #include #include "spdk/bdev.h" #include "spdk/event.h" #include "spdk/queue.h" #include "spdk/scsi_spec.h" /** \page block_backend_modules Block Device Backend Modules To implement a backend block device driver, a number of functions dictated by struct spdk_bdev_fn_table must be provided. The module should register itself using SPDK_BDEV_MODULE_REGISTER or SPDK_VBDEV_MODULE_REGISTER to define the parameters for the module. Use SPDK_BDEV_MODULE_REGISTER for all block backends that are real disks. Any virtual backends such as RAID, partitioning, etc. should use SPDK_VBDEV_MODULE_REGISTER.
In the module initialization code, the config file sections can be parsed to acquire custom configuration parameters. For example, if the config file has a section such as below: 
[MyBE]
  MyParam 1234
The value can be extracted as the example below: 
struct spdk_conf_section *sp = spdk_conf_find_section(NULL, "MyBe");
int my_param = spdk_conf_section_get_intval(sp, "MyParam");
The backend initialization routine also need to create "disks". A virtual representation of each LUN must be constructed. Mainly a struct spdk_bdev must be passed to the bdev database via spdk_bdev_register(). */ /** Block device module */ struct spdk_bdev_module_if { /** * Initialization function for the module. Called by the spdk * application during startup. * * Modules are required to define this function. */ int (*module_init)(void); /** * Finish function for the module. Called by the spdk application * before the spdk application exits to perform any necessary cleanup. * * 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); /** Name for the modules being defined. */ const char *module_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); TAILQ_ENTRY(spdk_bdev_module_if) tailq; }; /** * 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); /** 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); /** * Output driver-specific configuration 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_config_json)(struct spdk_bdev *bdev, struct spdk_json_write_ctx *w); }; void spdk_bdev_register(struct spdk_bdev *bdev); void spdk_bdev_io_get_rbuf(struct spdk_bdev_io *bdev_io, spdk_bdev_io_get_rbuf_cb cb); struct spdk_bdev_io *spdk_bdev_get_io(void); struct spdk_bdev_io *spdk_bdev_get_child_io(struct spdk_bdev_io *parent, struct spdk_bdev *bdev, spdk_bdev_io_completion_cb cb, void *cb_arg); void spdk_bdev_io_resubmit(struct spdk_bdev_io *bdev_io, struct spdk_bdev *new_bdev); 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. * * \param bdev_io I/O to complete. * \param sct NVMe Status Code Type. * \param sc NVMe Status Code. */ void spdk_bdev_io_complete_nvme_status(struct spdk_bdev_io *bdev_io, int sct, int sc); void spdk_bdev_module_list_add(struct spdk_bdev_module_if *bdev_module); void spdk_vbdev_module_list_add(struct spdk_bdev_module_if *vbdev_module); static inline struct spdk_bdev_io * spdk_bdev_io_from_ctx(void *ctx) { return (struct spdk_bdev_io *) ((uintptr_t)ctx - offsetof(struct spdk_bdev_io, driver_ctx)); } #define SPDK_BDEV_MODULE_REGISTER(init_fn, fini_fn, config_fn, ctx_size_fn) \ static struct spdk_bdev_module_if init_fn ## _if = { \ .module_init = init_fn, \ .module_fini = fini_fn, \ .config_text = config_fn, \ .get_ctx_size = ctx_size_fn, \ }; \ __attribute__((constructor)) static void init_fn ## _init(void) \ { \ spdk_bdev_module_list_add(&init_fn ## _if); \ } #define SPDK_VBDEV_MODULE_REGISTER(init_fn, fini_fn, config_fn, ctx_size_fn) \ static struct spdk_bdev_module_if init_fn ## _if = { \ .module_init = init_fn, \ .module_fini = fini_fn, \ .config_text = config_fn, \ .get_ctx_size = ctx_size_fn, \ }; \ __attribute__((constructor)) static void init_fn ## _init(void) \ { \ spdk_vbdev_module_list_add(&init_fn ## _if); \ } #endif /* SPDK_INTERNAL_BDEV_H */