/*******************************************************************************
   * Filename:  target_core_file.c
   *
   * This file contains the Storage Engine <-> FILEIO transport specific functions
   *
   * Copyright (c) 2005 PyX Technologies, Inc.
   * Copyright (c) 2005-2006 SBE, Inc.  All Rights Reserved.
   * Copyright (c) 2007-2010 Rising Tide Systems
   * Copyright (c) 2008-2010 Linux-iSCSI.org
   *
   * Nicholas A. Bellinger <nab@kernel.org>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   *
   ******************************************************************************/

  #include <linux/string.h>
  #include <linux/parser.h>
  #include <linux/timer.h>
  #include <linux/blkdev.h>
  #include <linux/slab.h>
  #include <linux/spinlock.h>

  #include <linux/module.h>

  #include <scsi/scsi.h>
  #include <scsi/scsi_host.h>
  
  #include <target/target_core_base.h>
  #include <target/target_core_device.h>
  #include <target/target_core_transport.h>
  
  #include "target_core_file.h"

  static struct se_subsystem_api fileio_template;
  
  /*	fd_attach_hba(): (Part of se_subsystem_api_t template)
   *
   *
   */
  static int fd_attach_hba(struct se_hba *hba, u32 host_id)
  {
  	struct fd_host *fd_host;
  
  	fd_host = kzalloc(sizeof(struct fd_host), GFP_KERNEL);

  	if (!fd_host) {
  		pr_err("Unable to allocate memory for struct fd_host
  ");

  		return -ENOMEM;

  	}
  
  	fd_host->fd_host_id = host_id;

  	hba->hba_ptr = fd_host;

  	pr_debug("CORE_HBA[%d] - TCM FILEIO HBA Driver %s on Generic"

  		" Target Core Stack %s
  ", hba->hba_id, FD_VERSION,
  		TARGET_CORE_MOD_VERSION);

  	pr_debug("CORE_HBA[%d] - Attached FILEIO HBA: %u to Generic"

  		" MaxSectors: %u
  ",
  		hba->hba_id, fd_host->fd_host_id, FD_MAX_SECTORS);

  
  	return 0;
  }
  
  static void fd_detach_hba(struct se_hba *hba)
  {
  	struct fd_host *fd_host = hba->hba_ptr;

  	pr_debug("CORE_HBA[%d] - Detached FILEIO HBA: %u from Generic"

  		" Target Core
  ", hba->hba_id, fd_host->fd_host_id);
  
  	kfree(fd_host);
  	hba->hba_ptr = NULL;
  }
  
  static void *fd_allocate_virtdevice(struct se_hba *hba, const char *name)
  {
  	struct fd_dev *fd_dev;
  	struct fd_host *fd_host = (struct fd_host *) hba->hba_ptr;
  
  	fd_dev = kzalloc(sizeof(struct fd_dev), GFP_KERNEL);

  	if (!fd_dev) {
  		pr_err("Unable to allocate memory for struct fd_dev
  ");

  		return NULL;
  	}
  
  	fd_dev->fd_host = fd_host;

  	pr_debug("FILEIO: Allocated fd_dev for %p
  ", name);

  
  	return fd_dev;
  }
  
  /*	fd_create_virtdevice(): (Part of se_subsystem_api_t template)
   *
   *
   */
  static struct se_device *fd_create_virtdevice(
  	struct se_hba *hba,
  	struct se_subsystem_dev *se_dev,
  	void *p)
  {
  	char *dev_p = NULL;
  	struct se_device *dev;
  	struct se_dev_limits dev_limits;
  	struct queue_limits *limits;
  	struct fd_dev *fd_dev = (struct fd_dev *) p;
  	struct fd_host *fd_host = (struct fd_host *) hba->hba_ptr;
  	mm_segment_t old_fs;
  	struct file *file;
  	struct inode *inode = NULL;

  	int dev_flags = 0, flags, ret = -EINVAL;

  
  	memset(&dev_limits, 0, sizeof(struct se_dev_limits));
  
  	old_fs = get_fs();
  	set_fs(get_ds());
  	dev_p = getname(fd_dev->fd_dev_name);
  	set_fs(old_fs);
  
  	if (IS_ERR(dev_p)) {

  		pr_err("getname(%s) failed: %lu
  ",

  			fd_dev->fd_dev_name, IS_ERR(dev_p));

  		ret = PTR_ERR(dev_p);

  		goto fail;
  	}
  #if 0
  	if (di->no_create_file)
  		flags = O_RDWR | O_LARGEFILE;
  	else
  		flags = O_RDWR | O_CREAT | O_LARGEFILE;
  #else
  	flags = O_RDWR | O_CREAT | O_LARGEFILE;
  #endif
  /*	flags |= O_DIRECT; */
  	/*

  	 * If fd_buffered_io=1 has not been set explicitly (the default),

  	 * use O_SYNC to force FILEIO writes to disk.
  	 */
  	if (!(fd_dev->fbd_flags & FDBD_USE_BUFFERED_IO))
  		flags |= O_SYNC;
  
  	file = filp_open(dev_p, flags, 0600);

  	if (IS_ERR(file)) {

  		pr_err("filp_open(%s) failed
  ", dev_p);

  		ret = PTR_ERR(file);
  		goto fail;
  	}
  	if (!file || !file->f_dentry) {

  		pr_err("filp_open(%s) failed
  ", dev_p);

  		goto fail;
  	}
  	fd_dev->fd_file = file;
  	/*
  	 * If using a block backend with this struct file, we extract
  	 * fd_dev->fd_[block,dev]_size from struct block_device.
  	 *
  	 * Otherwise, we use the passed fd_size= from configfs
  	 */
  	inode = file->f_mapping->host;
  	if (S_ISBLK(inode->i_mode)) {
  		struct request_queue *q;
  		/*
  		 * Setup the local scope queue_limits from struct request_queue->limits
  		 * to pass into transport_add_device_to_core_hba() as struct se_dev_limits.
  		 */
  		q = bdev_get_queue(inode->i_bdev);
  		limits = &dev_limits.limits;
  		limits->logical_block_size = bdev_logical_block_size(inode->i_bdev);
  		limits->max_hw_sectors = queue_max_hw_sectors(q);
  		limits->max_sectors = queue_max_sectors(q);
  		/*
  		 * Determine the number of bytes from i_size_read() minus
  		 * one (1) logical sector from underlying struct block_device
  		 */
  		fd_dev->fd_block_size = bdev_logical_block_size(inode->i_bdev);
  		fd_dev->fd_dev_size = (i_size_read(file->f_mapping->host) -
  				       fd_dev->fd_block_size);

  		pr_debug("FILEIO: Using size: %llu bytes from struct"

  			" block_device blocks: %llu logical_block_size: %d
  ",
  			fd_dev->fd_dev_size,
  			div_u64(fd_dev->fd_dev_size, fd_dev->fd_block_size),
  			fd_dev->fd_block_size);
  	} else {
  		if (!(fd_dev->fbd_flags & FBDF_HAS_SIZE)) {

  			pr_err("FILEIO: Missing fd_dev_size="

  				" parameter, and no backing struct"
  				" block_device
  ");
  			goto fail;
  		}
  
  		limits = &dev_limits.limits;
  		limits->logical_block_size = FD_BLOCKSIZE;
  		limits->max_hw_sectors = FD_MAX_SECTORS;
  		limits->max_sectors = FD_MAX_SECTORS;
  		fd_dev->fd_block_size = FD_BLOCKSIZE;
  	}
  
  	dev_limits.hw_queue_depth = FD_MAX_DEVICE_QUEUE_DEPTH;
  	dev_limits.queue_depth = FD_DEVICE_QUEUE_DEPTH;
  
  	dev = transport_add_device_to_core_hba(hba, &fileio_template,

  				se_dev, dev_flags, fd_dev,

  				&dev_limits, "FILEIO", FD_VERSION);

  	if (!dev)

  		goto fail;
  
  	fd_dev->fd_dev_id = fd_host->fd_host_dev_id_count++;
  	fd_dev->fd_queue_depth = dev->queue_depth;

  	pr_debug("CORE_FILE[%u] - Added TCM FILEIO Device ID: %u at %s,"

  		" %llu total bytes
  ", fd_host->fd_host_id, fd_dev->fd_dev_id,
  			fd_dev->fd_dev_name, fd_dev->fd_dev_size);
  
  	putname(dev_p);
  	return dev;
  fail:
  	if (fd_dev->fd_file) {
  		filp_close(fd_dev->fd_file, NULL);
  		fd_dev->fd_file = NULL;
  	}
  	putname(dev_p);

  	return ERR_PTR(ret);

  }
  
  /*	fd_free_device(): (Part of se_subsystem_api_t template)
   *
   *
   */
  static void fd_free_device(void *p)
  {
  	struct fd_dev *fd_dev = (struct fd_dev *) p;
  
  	if (fd_dev->fd_file) {
  		filp_close(fd_dev->fd_file, NULL);
  		fd_dev->fd_file = NULL;
  	}
  
  	kfree(fd_dev);
  }
  
  static inline struct fd_request *FILE_REQ(struct se_task *task)
  {
  	return container_of(task, struct fd_request, fd_task);
  }
  
  
  static struct se_task *

  fd_alloc_task(unsigned char *cdb)

  {
  	struct fd_request *fd_req;
  
  	fd_req = kzalloc(sizeof(struct fd_request), GFP_KERNEL);

  	if (!fd_req) {
  		pr_err("Unable to allocate struct fd_request
  ");

  		return NULL;
  	}

  	return &fd_req->fd_task;
  }
  
  static int fd_do_readv(struct se_task *task)
  {
  	struct fd_request *req = FILE_REQ(task);

  	struct se_device *se_dev = req->fd_task.task_se_cmd->se_dev;
  	struct fd_dev *dev = se_dev->dev_ptr;

  	struct file *fd = dev->fd_file;

  	struct scatterlist *sg = task->task_sg;
  	struct iovec *iov;
  	mm_segment_t old_fs;

  	loff_t pos = (task->task_lba *

  		      se_dev->se_sub_dev->se_dev_attrib.block_size);

  	int ret = 0, i;

  	iov = kzalloc(sizeof(struct iovec) * task->task_sg_nents, GFP_KERNEL);
  	if (!iov) {
  		pr_err("Unable to allocate fd_do_readv iov[]
  ");

  		return -ENOMEM;

  	}

  	for_each_sg(task->task_sg, sg, task->task_sg_nents, i) {
  		iov[i].iov_len = sg->length;
  		iov[i].iov_base = sg_virt(sg);

  	}
  
  	old_fs = get_fs();
  	set_fs(get_ds());

  	ret = vfs_readv(fd, &iov[0], task->task_sg_nents, &pos);

  	set_fs(old_fs);
  
  	kfree(iov);
  	/*
  	 * Return zeros and GOOD status even if the READ did not return
  	 * the expected virt_size for struct file w/o a backing struct
  	 * block_device.
  	 */
  	if (S_ISBLK(fd->f_dentry->d_inode->i_mode)) {
  		if (ret < 0 || ret != task->task_size) {

  			pr_err("vfs_readv() returned %d,"

  				" expecting %d for S_ISBLK
  ", ret,
  				(int)task->task_size);

  			return (ret < 0 ? ret : -EINVAL);

  		}
  	} else {
  		if (ret < 0) {

  			pr_err("vfs_readv() returned %d for non"

  				" S_ISBLK
  ", ret);

  			return ret;

  		}
  	}
  
  	return 1;
  }
  
  static int fd_do_writev(struct se_task *task)
  {
  	struct fd_request *req = FILE_REQ(task);

  	struct se_device *se_dev = req->fd_task.task_se_cmd->se_dev;
  	struct fd_dev *dev = se_dev->dev_ptr;

  	struct file *fd = dev->fd_file;

  	struct scatterlist *sg = task->task_sg;
  	struct iovec *iov;
  	mm_segment_t old_fs;

  	loff_t pos = (task->task_lba *

  		      se_dev->se_sub_dev->se_dev_attrib.block_size);

  	int ret, i = 0;

  	iov = kzalloc(sizeof(struct iovec) * task->task_sg_nents, GFP_KERNEL);
  	if (!iov) {
  		pr_err("Unable to allocate fd_do_writev iov[]
  ");

  		return -ENOMEM;

  	}

  	for_each_sg(task->task_sg, sg, task->task_sg_nents, i) {
  		iov[i].iov_len = sg->length;
  		iov[i].iov_base = sg_virt(sg);

  	}
  
  	old_fs = get_fs();
  	set_fs(get_ds());

  	ret = vfs_writev(fd, &iov[0], task->task_sg_nents, &pos);

  	set_fs(old_fs);
  
  	kfree(iov);
  
  	if (ret < 0 || ret != task->task_size) {

  		pr_err("vfs_writev() returned %d
  ", ret);

  		return (ret < 0 ? ret : -EINVAL);

  	}
  
  	return 1;
  }
  
  static void fd_emulate_sync_cache(struct se_task *task)
  {

  	struct se_cmd *cmd = task->task_se_cmd;

  	struct se_device *dev = cmd->se_dev;
  	struct fd_dev *fd_dev = dev->dev_ptr;

  	int immed = (cmd->t_task_cdb[1] & 0x2);

  	loff_t start, end;
  	int ret;
  
  	/*
  	 * If the Immediate bit is set, queue up the GOOD response
  	 * for this SYNCHRONIZE_CACHE op
  	 */
  	if (immed)
  		transport_complete_sync_cache(cmd, 1);
  
  	/*
  	 * Determine if we will be flushing the entire device.
  	 */

  	if (cmd->t_task_lba == 0 && cmd->data_length == 0) {

  		start = 0;
  		end = LLONG_MAX;
  	} else {

  		start = cmd->t_task_lba * dev->se_sub_dev->se_dev_attrib.block_size;

  		if (cmd->data_length)
  			end = start + cmd->data_length;
  		else
  			end = LLONG_MAX;
  	}
  
  	ret = vfs_fsync_range(fd_dev->fd_file, start, end, 1);
  	if (ret != 0)

  		pr_err("FILEIO: vfs_fsync_range() failed: %d
  ", ret);

  
  	if (!immed)
  		transport_complete_sync_cache(cmd, ret == 0);
  }
  
  /*

   * WRITE Force Unit Access (FUA) emulation on a per struct se_task
   * LBA range basis..
   */
  static void fd_emulate_write_fua(struct se_cmd *cmd, struct se_task *task)
  {
  	struct se_device *dev = cmd->se_dev;
  	struct fd_dev *fd_dev = dev->dev_ptr;

  	loff_t start = task->task_lba * dev->se_sub_dev->se_dev_attrib.block_size;

  	loff_t end = start + task->task_size;
  	int ret;

  	pr_debug("FILEIO: FUA WRITE LBA: %llu, bytes: %u
  ",

  			task->task_lba, task->task_size);
  
  	ret = vfs_fsync_range(fd_dev->fd_file, start, end, 1);
  	if (ret != 0)

  		pr_err("FILEIO: vfs_fsync_range() failed: %d
  ", ret);

  }
  
  static int fd_do_task(struct se_task *task)
  {
  	struct se_cmd *cmd = task->task_se_cmd;
  	struct se_device *dev = cmd->se_dev;
  	int ret = 0;
  
  	/*
  	 * Call vectorized fileio functions to map struct scatterlist
  	 * physical memory addresses to struct iovec virtual memory.
  	 */
  	if (task->task_data_direction == DMA_FROM_DEVICE) {
  		ret = fd_do_readv(task);
  	} else {
  		ret = fd_do_writev(task);
  
  		if (ret > 0 &&

  		    dev->se_sub_dev->se_dev_attrib.emulate_write_cache > 0 &&
  		    dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0 &&

  		    (cmd->se_cmd_flags & SCF_FUA)) {

  			/*
  			 * We might need to be a bit smarter here
  			 * and return some sense data to let the initiator
  			 * know the FUA WRITE cache sync failed..?
  			 */
  			fd_emulate_write_fua(cmd, task);
  		}
  
  	}

  	if (ret < 0) {
  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

  		return ret;

  	}

  	if (ret) {
  		task->task_scsi_status = GOOD;
  		transport_complete_task(task, 1);
  	}

  	return 0;

  }
  
  /*	fd_free_task(): (Part of se_subsystem_api_t template)
   *
   *
   */
  static void fd_free_task(struct se_task *task)
  {
  	struct fd_request *req = FILE_REQ(task);
  
  	kfree(req);
  }
  
  enum {
  	Opt_fd_dev_name, Opt_fd_dev_size, Opt_fd_buffered_io, Opt_err
  };
  
  static match_table_t tokens = {
  	{Opt_fd_dev_name, "fd_dev_name=%s"},
  	{Opt_fd_dev_size, "fd_dev_size=%s"},

  	{Opt_fd_buffered_io, "fd_buffered_io=%d"},

  	{Opt_err, NULL}
  };
  
  static ssize_t fd_set_configfs_dev_params(
  	struct se_hba *hba,
  	struct se_subsystem_dev *se_dev,
  	const char *page, ssize_t count)
  {
  	struct fd_dev *fd_dev = se_dev->se_dev_su_ptr;
  	char *orig, *ptr, *arg_p, *opts;
  	substring_t args[MAX_OPT_ARGS];
  	int ret = 0, arg, token;
  
  	opts = kstrdup(page, GFP_KERNEL);
  	if (!opts)
  		return -ENOMEM;
  
  	orig = opts;
  
  	while ((ptr = strsep(&opts, ",")) != NULL) {
  		if (!*ptr)
  			continue;
  
  		token = match_token(ptr, tokens, args);
  		switch (token) {
  		case Opt_fd_dev_name:

  			arg_p = match_strdup(&args[0]);
  			if (!arg_p) {
  				ret = -ENOMEM;
  				break;
  			}

  			snprintf(fd_dev->fd_dev_name, FD_MAX_DEV_NAME,

  					"%s", arg_p);
  			kfree(arg_p);

  			pr_debug("FILEIO: Referencing Path: %s
  ",

  					fd_dev->fd_dev_name);
  			fd_dev->fbd_flags |= FBDF_HAS_PATH;
  			break;
  		case Opt_fd_dev_size:
  			arg_p = match_strdup(&args[0]);

  			if (!arg_p) {
  				ret = -ENOMEM;
  				break;
  			}

  			ret = strict_strtoull(arg_p, 0, &fd_dev->fd_dev_size);

  			kfree(arg_p);

  			if (ret < 0) {

  				pr_err("strict_strtoull() failed for"

  						" fd_dev_size=
  ");
  				goto out;
  			}

  			pr_debug("FILEIO: Referencing Size: %llu"

  					" bytes
  ", fd_dev->fd_dev_size);
  			fd_dev->fbd_flags |= FBDF_HAS_SIZE;
  			break;
  		case Opt_fd_buffered_io:
  			match_int(args, &arg);
  			if (arg != 1) {

  				pr_err("bogus fd_buffered_io=%d value
  ", arg);

  				ret = -EINVAL;
  				goto out;
  			}

  			pr_debug("FILEIO: Using buffered I/O"

  				" operations for struct fd_dev
  ");
  
  			fd_dev->fbd_flags |= FDBD_USE_BUFFERED_IO;
  			break;
  		default:
  			break;
  		}
  	}
  
  out:
  	kfree(orig);
  	return (!ret) ? count : ret;
  }
  
  static ssize_t fd_check_configfs_dev_params(struct se_hba *hba, struct se_subsystem_dev *se_dev)
  {
  	struct fd_dev *fd_dev = (struct fd_dev *) se_dev->se_dev_su_ptr;
  
  	if (!(fd_dev->fbd_flags & FBDF_HAS_PATH)) {

  		pr_err("Missing fd_dev_name=
  ");

  		return -EINVAL;

  	}
  
  	return 0;
  }
  
  static ssize_t fd_show_configfs_dev_params(
  	struct se_hba *hba,
  	struct se_subsystem_dev *se_dev,
  	char *b)
  {
  	struct fd_dev *fd_dev = se_dev->se_dev_su_ptr;
  	ssize_t bl = 0;
  
  	bl = sprintf(b + bl, "TCM FILEIO ID: %u", fd_dev->fd_dev_id);
  	bl += sprintf(b + bl, "        File: %s  Size: %llu  Mode: %s
  ",
  		fd_dev->fd_dev_name, fd_dev->fd_dev_size,
  		(fd_dev->fbd_flags & FDBD_USE_BUFFERED_IO) ?
  		"Buffered" : "Synchronous");
  	return bl;
  }

  /*	fd_get_device_rev(): (Part of se_subsystem_api_t template)
   *
   *
   */
  static u32 fd_get_device_rev(struct se_device *dev)
  {
  	return SCSI_SPC_2; /* Returns SPC-3 in Initiator Data */
  }
  
  /*	fd_get_device_type(): (Part of se_subsystem_api_t template)
   *
   *
   */
  static u32 fd_get_device_type(struct se_device *dev)
  {
  	return TYPE_DISK;
  }
  
  static sector_t fd_get_blocks(struct se_device *dev)
  {
  	struct fd_dev *fd_dev = dev->dev_ptr;
  	unsigned long long blocks_long = div_u64(fd_dev->fd_dev_size,

  			dev->se_sub_dev->se_dev_attrib.block_size);

  
  	return blocks_long;
  }
  
  static struct se_subsystem_api fileio_template = {
  	.name			= "fileio",
  	.owner			= THIS_MODULE,
  	.transport_type		= TRANSPORT_PLUGIN_VHBA_PDEV,

  	.write_cache_emulated	= 1,
  	.fua_write_emulated	= 1,

  	.attach_hba		= fd_attach_hba,
  	.detach_hba		= fd_detach_hba,
  	.allocate_virtdevice	= fd_allocate_virtdevice,
  	.create_virtdevice	= fd_create_virtdevice,
  	.free_device		= fd_free_device,

  	.alloc_task		= fd_alloc_task,
  	.do_task		= fd_do_task,
  	.do_sync_cache		= fd_emulate_sync_cache,
  	.free_task		= fd_free_task,
  	.check_configfs_dev_params = fd_check_configfs_dev_params,
  	.set_configfs_dev_params = fd_set_configfs_dev_params,
  	.show_configfs_dev_params = fd_show_configfs_dev_params,

  	.get_device_rev		= fd_get_device_rev,
  	.get_device_type	= fd_get_device_type,
  	.get_blocks		= fd_get_blocks,
  };
  
  static int __init fileio_module_init(void)
  {
  	return transport_subsystem_register(&fileio_template);
  }
  
  static void fileio_module_exit(void)
  {
  	transport_subsystem_release(&fileio_template);
  }
  
  MODULE_DESCRIPTION("TCM FILEIO subsystem plugin");
  MODULE_AUTHOR("nab@Linux-iSCSI.org");
  MODULE_LICENSE("GPL");
  
  module_init(fileio_module_init);
  module_exit(fileio_module_exit);