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Date:	Sat, 02 Oct 2010 01:50:24 +0400
From:	Vladislav Bolkhovitin <vst@...b.net>
To:	linux-scsi@...r.kernel.org
CC:	linux-kernel@...r.kernel.org,
	scst-devel <scst-devel@...ts.sourceforge.net>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	Mike Christie <michaelc@...wisc.edu>,
	Vu Pham <vuhuong@...lanox.com>,
	Bart Van Assche <bart.vanassche@...il.com>,
	James Smart <James.Smart@...lex.Com>,
	Joe Eykholt <jeykholt@...co.com>, Andy Yan <ayan@...vell.com>,
	Chetan Loke <generationgnu@...oo.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Hannes Reinecke <hare@...e.de>,
	Richard Sharpe <realrichardsharpe@...il.com>
Subject: [PATCH 13/19]: SCST vdisk dev handler

This patch contains SCST vdisk dev handler. This dev handler allows
to create virtual disks and CDROMs from files on file system.

It supports the following modes:

 - FILEIO mode, which allows to use files on file systems or block
   devices as virtual remotely available SCSI disks or CDROMs with
   benefits of the Linux page cache.

 - BLOCKIO mode, which performs direct block IO with a block device,
   bypassing page-cache for all operations. This mode works ideally with
   high-end storage HBAs and for applications that either do not need
   caching between application and disk or need the large block
   throughput.

 - NULLIO mode, in which all the commands immediately completed. This mode
   is intended for performance measurements without overhead of actual data
   transfers from/to underlying SCSI device.

Signed-off-by: Vladislav Bolkhovitin <vst@...b.net>
---
 scst_vdisk.c | 4186 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 4186 insertions(+)

diff -uprN orig/linux-2.6.35/drivers/scst/dev_handlers/scst_vdisk.c linux-2.6.35/drivers/scst/dev_handlers/scst_vdisk.c
--- orig/linux-2.6.35/drivers/scst/dev_handlers/scst_vdisk.c
+++ linux-2.6.35/drivers/scst/dev_handlers/scst_vdisk.c
@@ -0,0 +1,4186 @@
+/*
+ *  scst_vdisk.c
+ *
+ *  Copyright (C) 2004 - 2010 Vladislav Bolkhovitin <vst@...b.net>
+ *  Copyright (C) 2004 - 2005 Leonid Stoljar
+ *  Copyright (C) 2007 Ming Zhang <blackmagic02881 at gmail dot com>
+ *  Copyright (C) 2007 Ross Walker <rswwalker at hotmail dot com>
+ *  Copyright (C) 2007 - 2010 ID7 Ltd.
+ *
+ *  SCSI disk (type 0) and CDROM (type 5) dev handler using files
+ *  on file systems or block devices (VDISK)
+ *
+ *  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, version 2
+ *  of the License.
+ *
+ *  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.
+ */
+
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/unistd.h>
+#include <linux/smp_lock.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/uio.h>
+#include <linux/list.h>
+#include <linux/ctype.h>
+#include <linux/writeback.h>
+#include <linux/vmalloc.h>
+#include <asm/atomic.h>
+#include <linux/kthread.h>
+#include <linux/sched.h>
+#include <linux/version.h>
+#include <asm/div64.h>
+#include <asm/unaligned.h>
+#include <linux/slab.h>
+#include <linux/bio.h>
+
+#define LOG_PREFIX			"dev_vdisk"
+
+#include <scst/scst.h>
+
+#if defined(CONFIG_SCST_DEBUG) || defined(CONFIG_SCST_TRACING)
+
+#define TRACE_ORDER	0x80000000
+
+static struct scst_trace_log vdisk_local_trace_tbl[] = {
+    { TRACE_ORDER,		"order" },
+    { 0,			NULL }
+};
+#define trace_log_tbl			vdisk_local_trace_tbl
+
+#define VDISK_TRACE_TLB_HELP	", order"
+
+#endif
+
+#include "scst_dev_handler.h"
+
+/* 8 byte ASCII Vendor */
+#define SCST_FIO_VENDOR			"SCST_FIO"
+#define SCST_BIO_VENDOR			"SCST_BIO"
+/* 4 byte ASCII Product Revision Level - left aligned */
+#define SCST_FIO_REV			" 210"
+
+#define MAX_USN_LEN			(20+1) /* For '\0' */
+
+#define INQ_BUF_SZ			256
+#define EVPD				0x01
+#define CMDDT				0x02
+
+#define MSENSE_BUF_SZ			256
+#define DBD				0x08	/* disable block descriptor */
+#define WP				0x80	/* write protect */
+#define DPOFUA				0x10	/* DPOFUA bit */
+#define WCE				0x04	/* write cache enable */
+
+#define PF				0x10	/* page format */
+#define SP				0x01	/* save pages */
+#define PS				0x80	/* parameter saveable */
+
+#define	BYTE				8
+#define	DEF_DISK_BLOCKSIZE_SHIFT	9
+#define	DEF_DISK_BLOCKSIZE		(1 << DEF_DISK_BLOCKSIZE_SHIFT)
+#define	DEF_CDROM_BLOCKSIZE_SHIFT	11
+#define	DEF_CDROM_BLOCKSIZE		(1 << DEF_CDROM_BLOCKSIZE_SHIFT)
+#define	DEF_SECTORS			56
+#define	DEF_HEADS			255
+#define LEN_MEM				(32 * 1024)
+#define DEF_RD_ONLY			0
+#define DEF_WRITE_THROUGH		0
+#define DEF_NV_CACHE			0
+#define DEF_O_DIRECT			0
+#define DEF_REMOVABLE			0
+#define DEF_THIN_PROVISIONED		0
+
+#define VDISK_NULLIO_SIZE		(3LL*1024*1024*1024*1024/2)
+
+#define DEF_TST				SCST_CONTR_MODE_SEP_TASK_SETS
+
+/*
+ * Since we can't control backstorage device's reordering, we have to always
+ * report unrestricted reordering.
+ */
+#define DEF_QUEUE_ALG_WT	SCST_CONTR_MODE_QUEUE_ALG_UNRESTRICTED_REORDER
+#define DEF_QUEUE_ALG		SCST_CONTR_MODE_QUEUE_ALG_UNRESTRICTED_REORDER
+#define DEF_SWP			0
+#define DEF_TAS			0
+
+#define DEF_DSENSE		SCST_CONTR_MODE_FIXED_SENSE
+
+static unsigned int random_values[256] = {
+	    9862592UL,  3744545211UL,  2348289082UL,  4036111983UL,
+	  435574201UL,  3110343764UL,  2383055570UL,  1826499182UL,
+	 4076766377UL,  1549935812UL,  3696752161UL,  1200276050UL,
+	 3878162706UL,  1783530428UL,  2291072214UL,   125807985UL,
+	 3407668966UL,   547437109UL,  3961389597UL,   969093968UL,
+	   56006179UL,  2591023451UL,     1849465UL,  1614540336UL,
+	 3699757935UL,   479961779UL,  3768703953UL,  2529621525UL,
+	 4157893312UL,  3673555386UL,  4091110867UL,  2193909423UL,
+	 2800464448UL,  3052113233UL,   450394455UL,  3424338713UL,
+	 2113709130UL,  4082064373UL,  3708640918UL,  3841182218UL,
+	 3141803315UL,  1032476030UL,  1166423150UL,  1169646901UL,
+	 2686611738UL,   575517645UL,  2829331065UL,  1351103339UL,
+	 2856560215UL,  2402488288UL,   867847666UL,     8524618UL,
+	  704790297UL,  2228765657UL,   231508411UL,  1425523814UL,
+	 2146764591UL,  1287631730UL,  4142687914UL,  3879884598UL,
+	  729945311UL,   310596427UL,  2263511876UL,  1983091134UL,
+	 3500916580UL,  1642490324UL,  3858376049UL,   695342182UL,
+	  780528366UL,  1372613640UL,  1100993200UL,  1314818946UL,
+	  572029783UL,  3775573540UL,   776262915UL,  2684520905UL,
+	 1007252738UL,  3505856396UL,  1974886670UL,  3115856627UL,
+	 4194842288UL,  2135793908UL,  3566210707UL,     7929775UL,
+	 1321130213UL,  2627281746UL,  3587067247UL,  2025159890UL,
+	 2587032000UL,  3098513342UL,  3289360258UL,   130594898UL,
+	 2258149812UL,  2275857755UL,  3966929942UL,  1521739999UL,
+	 4191192765UL,   958953550UL,  4153558347UL,  1011030335UL,
+	  524382185UL,  4099757640UL,   498828115UL,  2396978754UL,
+	  328688935UL,   826399828UL,  3174103611UL,  3921966365UL,
+	 2187456284UL,  2631406787UL,  3930669674UL,  4282803915UL,
+	 1776755417UL,   374959755UL,  2483763076UL,   844956392UL,
+	 2209187588UL,  3647277868UL,   291047860UL,  3485867047UL,
+	 2223103546UL,  2526736133UL,  3153407604UL,  3828961796UL,
+	 3355731910UL,  2322269798UL,  2752144379UL,   519897942UL,
+	 3430536488UL,  1801511593UL,  1953975728UL,  3286944283UL,
+	 1511612621UL,  1050133852UL,   409321604UL,  1037601109UL,
+	 3352316843UL,  4198371381UL,   617863284UL,   994672213UL,
+	 1540735436UL,  2337363549UL,  1242368492UL,   665473059UL,
+	 2330728163UL,  3443103219UL,  2291025133UL,  3420108120UL,
+	 2663305280UL,  1608969839UL,  2278959931UL,  1389747794UL,
+	 2226946970UL,  2131266900UL,  3856979144UL,  1894169043UL,
+	 2692697628UL,  3797290626UL,  3248126844UL,  3922786277UL,
+	  343705271UL,  3739749888UL,  2191310783UL,  2962488787UL,
+	 4119364141UL,  1403351302UL,  2984008923UL,  3822407178UL,
+	 1932139782UL,  2323869332UL,  2793574182UL,  1852626483UL,
+	 2722460269UL,  1136097522UL,  1005121083UL,  1805201184UL,
+	 2212824936UL,  2979547931UL,  4133075915UL,  2585731003UL,
+	 2431626071UL,   134370235UL,  3763236829UL,  1171434827UL,
+	 2251806994UL,  1289341038UL,  3616320525UL,   392218563UL,
+	 1544502546UL,  2993937212UL,  1957503701UL,  3579140080UL,
+	 4270846116UL,  2030149142UL,  1792286022UL,   366604999UL,
+	 2625579499UL,   790898158UL,   770833822UL,   815540197UL,
+	 2747711781UL,  3570468835UL,  3976195842UL,  1257621341UL,
+	 1198342980UL,  1860626190UL,  3247856686UL,   351473955UL,
+	  993440563UL,   340807146UL,  1041994520UL,  3573925241UL,
+	  480246395UL,  2104806831UL,  1020782793UL,  3362132583UL,
+	 2272911358UL,  3440096248UL,  2356596804UL,   259492703UL,
+	 3899500740UL,   252071876UL,  2177024041UL,  4284810959UL,
+	 2775999888UL,  2653420445UL,  2876046047UL,  1025771859UL,
+	 1994475651UL,  3564987377UL,  4112956647UL,  1821511719UL,
+	 3113447247UL,   455315102UL,  1585273189UL,  2311494568UL,
+	  774051541UL,  1898115372UL,  2637499516UL,   247231365UL,
+	 1475014417UL,   803585727UL,  3911097303UL,  1714292230UL,
+	  476579326UL,  2496900974UL,  3397613314UL,   341202244UL,
+	  807790202UL,  4221326173UL,   499979741UL,  1301488547UL,
+	 1056807896UL,  3525009458UL,  1174811641UL,  3049738746UL,
+};
+
+struct scst_vdisk_dev {
+	uint32_t block_size;
+	uint64_t nblocks;
+	int block_shift;
+	loff_t file_size;	/* in bytes */
+
+	/*
+	 * This lock can be taken on both SIRQ and thread context, but in
+	 * all cases for each particular instance it's taken consistenly either
+	 * on SIRQ or thread context. Mix of them is forbidden.
+	 */
+	spinlock_t flags_lock;
+
+	/*
+	 * Below flags are protected by flags_lock or suspended activity
+	 * with scst_vdisk_mutex.
+	 */
+	unsigned int rd_only:1;
+	unsigned int wt_flag:1;
+	unsigned int nv_cache:1;
+	unsigned int o_direct_flag:1;
+	unsigned int media_changed:1;
+	unsigned int prevent_allow_medium_removal:1;
+	unsigned int nullio:1;
+	unsigned int blockio:1;
+	unsigned int cdrom_empty:1;
+	unsigned int removable:1;
+	unsigned int thin_provisioned:1;
+
+	int virt_id;
+	char name[16+1];	/* Name of the virtual device,
+				   must be <= SCSI Model + 1 */
+	char *filename;		/* File name, protected by
+				   scst_mutex and suspended activities */
+	uint16_t command_set_version;
+	unsigned int t10_dev_id_set:1; /* true if t10_dev_id manually set */
+	char t10_dev_id[16+8+2]; /* T10 device ID */
+	char usn[MAX_USN_LEN];
+	struct scst_device *dev;
+	struct list_head vdev_list_entry;
+
+	struct scst_dev_type *vdev_devt;
+};
+
+struct scst_vdisk_thr {
+	struct scst_thr_data_hdr hdr;
+	struct file *fd;
+	struct block_device *bdev;
+	struct iovec *iv;
+	int iv_count;
+};
+
+/* Context RA patch supposed to be applied on the kernel */
+#define DEF_NUM_THREADS		8
+static int num_threads = DEF_NUM_THREADS;
+
+module_param_named(num_threads, num_threads, int, S_IRUGO);
+MODULE_PARM_DESC(num_threads, "vdisk threads count");
+
+static int vdisk_attach(struct scst_device *dev);
+static void vdisk_detach(struct scst_device *dev);
+static int vdisk_attach_tgt(struct scst_tgt_dev *tgt_dev);
+static void vdisk_detach_tgt(struct scst_tgt_dev *tgt_dev);
+static int vdisk_parse(struct scst_cmd *);
+static int vdisk_do_job(struct scst_cmd *cmd);
+static int vcdrom_parse(struct scst_cmd *);
+static int vcdrom_exec(struct scst_cmd *cmd);
+static void vdisk_exec_read(struct scst_cmd *cmd,
+	struct scst_vdisk_thr *thr, loff_t loff);
+static void vdisk_exec_write(struct scst_cmd *cmd,
+	struct scst_vdisk_thr *thr, loff_t loff);
+static void blockio_exec_rw(struct scst_cmd *cmd, struct scst_vdisk_thr *thr,
+	u64 lba_start, int write);
+static int blockio_flush(struct block_device *bdev);
+static void vdisk_exec_verify(struct scst_cmd *cmd,
+	struct scst_vdisk_thr *thr, loff_t loff);
+static void vdisk_exec_read_capacity(struct scst_cmd *cmd);
+static void vdisk_exec_read_capacity16(struct scst_cmd *cmd);
+static void vdisk_exec_inquiry(struct scst_cmd *cmd);
+static void vdisk_exec_request_sense(struct scst_cmd *cmd);
+static void vdisk_exec_mode_sense(struct scst_cmd *cmd);
+static void vdisk_exec_mode_select(struct scst_cmd *cmd);
+static void vdisk_exec_log(struct scst_cmd *cmd);
+static void vdisk_exec_read_toc(struct scst_cmd *cmd);
+static void vdisk_exec_prevent_allow_medium_removal(struct scst_cmd *cmd);
+static void vdisk_exec_unmap(struct scst_cmd *cmd, struct scst_vdisk_thr *thr);
+static int vdisk_fsync(struct scst_vdisk_thr *thr, loff_t loff,
+	loff_t len, struct scst_cmd *cmd, struct scst_device *dev);
+static ssize_t vdisk_add_fileio_device(const char *device_name, char *params);
+static ssize_t vdisk_add_blockio_device(const char *device_name, char *params);
+static ssize_t vdisk_add_nullio_device(const char *device_name, char *params);
+static ssize_t vdisk_del_device(const char *device_name);
+static ssize_t vcdrom_add_device(const char *device_name, char *params);
+static ssize_t vcdrom_del_device(const char *device_name);
+static int vdisk_task_mgmt_fn(struct scst_mgmt_cmd *mcmd,
+	struct scst_tgt_dev *tgt_dev);
+static uint64_t vdisk_gen_dev_id_num(const char *virt_dev_name);
+
+/** SYSFS **/
+
+static ssize_t vdev_sysfs_size_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+static ssize_t vdisk_sysfs_blocksize_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+static ssize_t vdisk_sysfs_rd_only_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+static ssize_t vdisk_sysfs_wt_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+static ssize_t vdisk_sysfs_tp_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+static ssize_t vdisk_sysfs_nv_cache_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+static ssize_t vdisk_sysfs_o_direct_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+static ssize_t vdisk_sysfs_removable_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+static ssize_t vdev_sysfs_filename_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+static ssize_t vdisk_sysfs_resync_size_store(struct kobject *kobj,
+	struct kobj_attribute *attr, const char *buf, size_t count);
+static ssize_t vdev_sysfs_t10_dev_id_store(struct kobject *kobj,
+	struct kobj_attribute *attr, const char *buf, size_t count);
+static ssize_t vdev_sysfs_t10_dev_id_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+static ssize_t vdev_sysfs_usn_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf);
+
+static ssize_t vcdrom_sysfs_filename_store(struct kobject *kobj,
+	struct kobj_attribute *attr, const char *buf, size_t count);
+
+static struct kobj_attribute vdev_size_attr =
+	__ATTR(size_mb, S_IRUGO, vdev_sysfs_size_show, NULL);
+static struct kobj_attribute vdisk_blocksize_attr =
+	__ATTR(blocksize, S_IRUGO, vdisk_sysfs_blocksize_show, NULL);
+static struct kobj_attribute vdisk_rd_only_attr =
+	__ATTR(read_only, S_IRUGO, vdisk_sysfs_rd_only_show, NULL);
+static struct kobj_attribute vdisk_wt_attr =
+	__ATTR(write_through, S_IRUGO, vdisk_sysfs_wt_show, NULL);
+static struct kobj_attribute vdisk_tp_attr =
+	__ATTR(thin_provisioned, S_IRUGO, vdisk_sysfs_tp_show, NULL);
+static struct kobj_attribute vdisk_nv_cache_attr =
+	__ATTR(nv_cache, S_IRUGO, vdisk_sysfs_nv_cache_show, NULL);
+static struct kobj_attribute vdisk_o_direct_attr =
+	__ATTR(o_direct, S_IRUGO, vdisk_sysfs_o_direct_show, NULL);
+static struct kobj_attribute vdisk_removable_attr =
+	__ATTR(removable, S_IRUGO, vdisk_sysfs_removable_show, NULL);
+static struct kobj_attribute vdisk_filename_attr =
+	__ATTR(filename, S_IRUGO, vdev_sysfs_filename_show, NULL);
+static struct kobj_attribute vdisk_resync_size_attr =
+	__ATTR(resync_size, S_IWUSR, NULL, vdisk_sysfs_resync_size_store);
+static struct kobj_attribute vdev_t10_dev_id_attr =
+	__ATTR(t10_dev_id, S_IWUSR|S_IRUGO, vdev_sysfs_t10_dev_id_show,
+		vdev_sysfs_t10_dev_id_store);
+static struct kobj_attribute vdev_usn_attr =
+	__ATTR(usn, S_IRUGO, vdev_sysfs_usn_show, NULL);
+
+static struct kobj_attribute vcdrom_filename_attr =
+	__ATTR(filename, S_IRUGO|S_IWUSR, vdev_sysfs_filename_show,
+		vcdrom_sysfs_filename_store);
+
+static const struct attribute *vdisk_fileio_attrs[] = {
+	&vdev_size_attr.attr,
+	&vdisk_blocksize_attr.attr,
+	&vdisk_rd_only_attr.attr,
+	&vdisk_wt_attr.attr,
+	&vdisk_tp_attr.attr,
+	&vdisk_nv_cache_attr.attr,
+	&vdisk_o_direct_attr.attr,
+	&vdisk_removable_attr.attr,
+	&vdisk_filename_attr.attr,
+	&vdisk_resync_size_attr.attr,
+	&vdev_t10_dev_id_attr.attr,
+	&vdev_usn_attr.attr,
+	NULL,
+};
+
+static const struct attribute *vdisk_blockio_attrs[] = {
+	&vdev_size_attr.attr,
+	&vdisk_blocksize_attr.attr,
+	&vdisk_rd_only_attr.attr,
+	&vdisk_nv_cache_attr.attr,
+	&vdisk_removable_attr.attr,
+	&vdisk_filename_attr.attr,
+	&vdisk_resync_size_attr.attr,
+	&vdev_t10_dev_id_attr.attr,
+	&vdev_usn_attr.attr,
+	&vdisk_tp_attr.attr,
+	NULL,
+};
+
+static const struct attribute *vdisk_nullio_attrs[] = {
+	&vdev_size_attr.attr,
+	&vdisk_blocksize_attr.attr,
+	&vdisk_rd_only_attr.attr,
+	&vdisk_removable_attr.attr,
+	&vdev_t10_dev_id_attr.attr,
+	&vdev_usn_attr.attr,
+	NULL,
+};
+
+static const struct attribute *vcdrom_attrs[] = {
+	&vdev_size_attr.attr,
+	&vcdrom_filename_attr.attr,
+	&vdev_t10_dev_id_attr.attr,
+	&vdev_usn_attr.attr,
+	NULL,
+};
+
+/* Protects vdisks addition/deletion and related activities, like search */
+static DEFINE_MUTEX(scst_vdisk_mutex);
+static DEFINE_RWLOCK(vdisk_t10_dev_id_rwlock);
+
+/* Protected by scst_vdisk_mutex */
+static LIST_HEAD(vdev_list);
+
+static struct kmem_cache *vdisk_thr_cachep;
+
+/*
+ * Be careful changing "name" field, since it is the name of the corresponding
+ * /sys/kernel/scst_tgt entry, hence a part of user space ABI.
+ */
+
+static struct scst_dev_type vdisk_file_devtype = {
+	.name =			"vdisk_fileio",
+	.type =			TYPE_DISK,
+	.exec_sync =		1,
+	.threads_num =		-1,
+	.parse_atomic =		1,
+	.dev_done_atomic =	1,
+	.attach =		vdisk_attach,
+	.detach =		vdisk_detach,
+	.attach_tgt =		vdisk_attach_tgt,
+	.detach_tgt =		vdisk_detach_tgt,
+	.parse =		vdisk_parse,
+	.exec =			vdisk_do_job,
+	.task_mgmt_fn =		vdisk_task_mgmt_fn,
+	.add_device =		vdisk_add_fileio_device,
+	.del_device =		vdisk_del_device,
+	.dev_attrs =		vdisk_fileio_attrs,
+	.add_device_parameters = "filename, blocksize, write_through, "
+		"nv_cache, o_direct, read_only, removable, thin_provisioned",
+#if defined(CONFIG_SCST_DEBUG) || defined(CONFIG_SCST_TRACING)
+	.default_trace_flags =	SCST_DEFAULT_DEV_LOG_FLAGS,
+	.trace_flags =		&trace_flag,
+	.trace_tbl =		vdisk_local_trace_tbl,
+	.trace_tbl_help =	VDISK_TRACE_TLB_HELP,
+#endif
+};
+
+static struct kmem_cache *blockio_work_cachep;
+
+static struct scst_dev_type vdisk_blk_devtype = {
+	.name =			"vdisk_blockio",
+	.type =			TYPE_DISK,
+	.threads_num =		1,
+	.parse_atomic =		1,
+	.dev_done_atomic =	1,
+	.attach =		vdisk_attach,
+	.detach =		vdisk_detach,
+	.attach_tgt =		vdisk_attach_tgt,
+	.detach_tgt =		vdisk_detach_tgt,
+	.parse =		vdisk_parse,
+	.exec =			vdisk_do_job,
+	.task_mgmt_fn =		vdisk_task_mgmt_fn,
+	.add_device =		vdisk_add_blockio_device,
+	.del_device =		vdisk_del_device,
+	.dev_attrs =		vdisk_blockio_attrs,
+	.add_device_parameters = "filename, blocksize, nv_cache, read_only, "
+		"removable, thin_provisioned",
+#if defined(CONFIG_SCST_DEBUG) || defined(CONFIG_SCST_TRACING)
+	.default_trace_flags =	SCST_DEFAULT_DEV_LOG_FLAGS,
+	.trace_flags =		&trace_flag,
+	.trace_tbl =		vdisk_local_trace_tbl,
+	.trace_tbl_help =	VDISK_TRACE_TLB_HELP,
+#endif
+};
+
+static struct scst_dev_type vdisk_null_devtype = {
+	.name =			"vdisk_nullio",
+	.type =			TYPE_DISK,
+	.threads_num =		0,
+	.parse_atomic =		1,
+	.dev_done_atomic =	1,
+	.attach =		vdisk_attach,
+	.detach =		vdisk_detach,
+	.attach_tgt =		vdisk_attach_tgt,
+	.detach_tgt =		vdisk_detach_tgt,
+	.parse =		vdisk_parse,
+	.exec =			vdisk_do_job,
+	.task_mgmt_fn =		vdisk_task_mgmt_fn,
+	.add_device =		vdisk_add_nullio_device,
+	.del_device =		vdisk_del_device,
+	.dev_attrs =		vdisk_nullio_attrs,
+	.add_device_parameters = "blocksize, read_only, removable",
+#if defined(CONFIG_SCST_DEBUG) || defined(CONFIG_SCST_TRACING)
+	.default_trace_flags =	SCST_DEFAULT_DEV_LOG_FLAGS,
+	.trace_flags =		&trace_flag,
+	.trace_tbl =		vdisk_local_trace_tbl,
+	.trace_tbl_help =	VDISK_TRACE_TLB_HELP,
+#endif
+};
+
+static struct scst_dev_type vcdrom_devtype = {
+	.name =			"vcdrom",
+	.type =			TYPE_ROM,
+	.exec_sync =		1,
+	.threads_num =		-1,
+	.parse_atomic =		1,
+	.dev_done_atomic =	1,
+	.attach =		vdisk_attach,
+	.detach =		vdisk_detach,
+	.attach_tgt =		vdisk_attach_tgt,
+	.detach_tgt =		vdisk_detach_tgt,
+	.parse =		vcdrom_parse,
+	.exec =			vcdrom_exec,
+	.task_mgmt_fn =		vdisk_task_mgmt_fn,
+	.add_device =		vcdrom_add_device,
+	.del_device =		vcdrom_del_device,
+	.dev_attrs =		vcdrom_attrs,
+	.add_device_parameters = NULL,
+#if defined(CONFIG_SCST_DEBUG) || defined(CONFIG_SCST_TRACING)
+	.default_trace_flags =	SCST_DEFAULT_DEV_LOG_FLAGS,
+	.trace_flags =		&trace_flag,
+	.trace_tbl =		vdisk_local_trace_tbl,
+	.trace_tbl_help =	VDISK_TRACE_TLB_HELP,
+#endif
+};
+
+static struct scst_vdisk_thr nullio_thr_data;
+
+static const char *vdev_get_filename(const struct scst_vdisk_dev *virt_dev)
+{
+	if (virt_dev->filename != NULL)
+		return virt_dev->filename;
+	else
+		return "none";
+}
+
+/* Returns fd, use IS_ERR(fd) to get error status */
+static struct file *vdev_open_fd(const struct scst_vdisk_dev *virt_dev)
+{
+	int open_flags = 0;
+	struct file *fd;
+
+	if (virt_dev->dev->rd_only)
+		open_flags |= O_RDONLY;
+	else
+		open_flags |= O_RDWR;
+	if (virt_dev->o_direct_flag)
+		open_flags |= O_DIRECT;
+	if (virt_dev->wt_flag && !virt_dev->nv_cache)
+		open_flags |= O_SYNC;
+	TRACE_DBG("Opening file %s, flags 0x%x",
+		  virt_dev->filename, open_flags);
+	fd = filp_open(virt_dev->filename, O_LARGEFILE | open_flags, 0600);
+	return fd;
+}
+
+static void vdisk_blockio_check_flush_support(struct scst_vdisk_dev *virt_dev)
+{
+	struct inode *inode;
+	struct file *fd;
+
+	if (!virt_dev->blockio || virt_dev->rd_only || virt_dev->nv_cache)
+		goto out;
+
+	fd = filp_open(virt_dev->filename, O_LARGEFILE, 0600);
+	if (IS_ERR(fd)) {
+		PRINT_ERROR("filp_open(%s) returned error %ld",
+			virt_dev->filename, PTR_ERR(fd));
+		goto out;
+	}
+
+	inode = fd->f_dentry->d_inode;
+
+	if (!S_ISBLK(inode->i_mode)) {
+		PRINT_ERROR("%s is NOT a block device", virt_dev->filename);
+		goto out_close;
+	}
+
+	if (blockio_flush(inode->i_bdev) != 0) {
+		PRINT_WARNING("Device %s doesn't support barriers, switching "
+			"to NV_CACHE mode. Read README for more details.",
+			virt_dev->filename);
+		virt_dev->nv_cache = 1;
+	}
+
+out_close:
+	filp_close(fd, NULL);
+
+out:
+	return;
+}
+
+static void vdisk_check_tp_support(struct scst_vdisk_dev *virt_dev)
+{
+	struct inode *inode;
+	struct file *fd;
+	bool supported = false;
+
+	if (virt_dev->rd_only || !virt_dev->thin_provisioned)
+		goto out;
+
+	fd = filp_open(virt_dev->filename, O_LARGEFILE, 0600);
+	if (IS_ERR(fd)) {
+		PRINT_ERROR("filp_open(%s) returned error %ld",
+			virt_dev->filename, PTR_ERR(fd));
+		goto out;
+	}
+
+	inode = fd->f_dentry->d_inode;
+
+	if (virt_dev->blockio) {
+		if (!S_ISBLK(inode->i_mode)) {
+			PRINT_ERROR("%s is NOT a block device",
+				virt_dev->filename);
+			goto out_close;
+		}
+		supported = blk_queue_discard(bdev_get_queue(inode->i_bdev));
+
+	} else {
+		/*
+		 * truncate_range() was chosen rather as a sample. In future,
+		 * when unmap of range of blocks in file become standard, we
+		 * will just switch to the new call.
+		 */
+		supported = (inode->i_op->truncate_range != NULL);
+	}
+
+	if (!supported) {
+		PRINT_WARNING("Device %s doesn't support thin "
+			"provisioning, disabling it.",
+			virt_dev->filename);
+		virt_dev->thin_provisioned = 0;
+	}
+
+out_close:
+	filp_close(fd, NULL);
+
+out:
+	return;
+}
+
+/* Returns 0 on success and file size in *file_size, error code otherwise */
+static int vdisk_get_file_size(const char *filename, bool blockio,
+	loff_t *file_size)
+{
+	struct inode *inode;
+	int res = 0;
+	struct file *fd;
+
+	*file_size = 0;
+
+	fd = filp_open(filename, O_LARGEFILE | O_RDONLY, 0600);
+	if (IS_ERR(fd)) {
+		res = PTR_ERR(fd);
+		PRINT_ERROR("filp_open(%s) returned error %d", filename, res);
+		goto out;
+	}
+
+	inode = fd->f_dentry->d_inode;
+
+	if (blockio && !S_ISBLK(inode->i_mode)) {
+		PRINT_ERROR("File %s is NOT a block device", filename);
+		res = -EINVAL;
+		goto out_close;
+	}
+
+	if (S_ISREG(inode->i_mode))
+		/* Nothing to do */;
+	else if (S_ISBLK(inode->i_mode))
+		inode = inode->i_bdev->bd_inode;
+	else {
+		res = -EINVAL;
+		goto out_close;
+	}
+
+	*file_size = inode->i_size;
+
+out_close:
+	filp_close(fd, NULL);
+
+out:
+	return res;
+}
+
+static int vdisk_attach(struct scst_device *dev)
+{
+	int res = 0;
+	loff_t err;
+	struct scst_vdisk_dev *virt_dev = NULL, *vv;
+
+	TRACE_DBG("virt_id %d (%s)", dev->virt_id, dev->virt_name);
+
+	if (dev->virt_id == 0) {
+		PRINT_ERROR("%s", "Not a virtual device");
+		res = -EINVAL;
+		goto out;
+	}
+
+	/*
+	 * scst_vdisk_mutex must be already taken before
+	 * scst_register_virtual_device()
+	 */
+	list_for_each_entry(vv, &vdev_list, vdev_list_entry) {
+		if (strcmp(vv->name, dev->virt_name) == 0) {
+			virt_dev = vv;
+			break;
+		}
+	}
+
+	if (virt_dev == NULL) {
+		PRINT_ERROR("Device %s not found", dev->virt_name);
+		res = -EINVAL;
+		goto out;
+	}
+
+	virt_dev->dev = dev;
+
+	dev->rd_only = virt_dev->rd_only;
+
+	if (!virt_dev->cdrom_empty) {
+		if (virt_dev->nullio)
+			err = VDISK_NULLIO_SIZE;
+		else {
+			res = vdisk_get_file_size(virt_dev->filename,
+				virt_dev->blockio, &err);
+			if (res != 0)
+				goto out;
+		}
+		virt_dev->file_size = err;
+
+		TRACE_DBG("size of file: %lld", (long long unsigned int)err);
+
+		vdisk_blockio_check_flush_support(virt_dev);
+		vdisk_check_tp_support(virt_dev);
+	} else
+		virt_dev->file_size = 0;
+
+	virt_dev->nblocks = virt_dev->file_size >> virt_dev->block_shift;
+
+	if (!virt_dev->cdrom_empty) {
+		PRINT_INFO("Attached SCSI target virtual %s %s "
+		      "(file=\"%s\", fs=%lldMB, bs=%d, nblocks=%lld,"
+		      " cyln=%lld%s)",
+		      (dev->type == TYPE_DISK) ? "disk" : "cdrom",
+		      virt_dev->name, vdev_get_filename(virt_dev),
+		      virt_dev->file_size >> 20, virt_dev->block_size,
+		      (long long unsigned int)virt_dev->nblocks,
+		      (long long unsigned int)virt_dev->nblocks/64/32,
+		      virt_dev->nblocks < 64*32
+		      ? " !WARNING! cyln less than 1" : "");
+	} else {
+		PRINT_INFO("Attached empty SCSI target virtual cdrom %s",
+			virt_dev->name);
+	}
+
+	dev->dh_priv = virt_dev;
+
+	dev->tst = DEF_TST;
+	dev->d_sense = DEF_DSENSE;
+	if (virt_dev->wt_flag && !virt_dev->nv_cache)
+		dev->queue_alg = DEF_QUEUE_ALG_WT;
+	else
+		dev->queue_alg = DEF_QUEUE_ALG;
+	dev->swp = DEF_SWP;
+	dev->tas = DEF_TAS;
+
+out:
+	return res;
+}
+
+/* scst_mutex supposed to be held */
+static void vdisk_detach(struct scst_device *dev)
+{
+	struct scst_vdisk_dev *virt_dev =
+	    (struct scst_vdisk_dev *)dev->dh_priv;
+
+	TRACE_DBG("virt_id %d", dev->virt_id);
+
+	PRINT_INFO("Detached virtual device %s (\"%s\")",
+		      virt_dev->name, vdev_get_filename(virt_dev));
+
+	/* virt_dev will be freed by the caller */
+	dev->dh_priv = NULL;
+	return;
+}
+
+static void vdisk_free_thr_data(struct scst_thr_data_hdr *d)
+{
+	struct scst_vdisk_thr *thr =
+		container_of(d, struct scst_vdisk_thr, hdr);
+
+	if (thr->fd)
+		filp_close(thr->fd, NULL);
+
+	kfree(thr->iv);
+
+	kmem_cache_free(vdisk_thr_cachep, thr);
+	return;
+}
+
+static struct scst_vdisk_thr *vdisk_init_thr_data(
+	struct scst_tgt_dev *tgt_dev)
+{
+	struct scst_vdisk_thr *res;
+	struct scst_vdisk_dev *virt_dev =
+	    (struct scst_vdisk_dev *)tgt_dev->dev->dh_priv;
+
+	EXTRACHECKS_BUG_ON(virt_dev->nullio);
+
+	res = kmem_cache_zalloc(vdisk_thr_cachep, GFP_KERNEL);
+	if (res == NULL) {
+		TRACE(TRACE_OUT_OF_MEM, "%s", "Unable to allocate struct "
+			"scst_vdisk_thr");
+		goto out;
+	}
+
+	if (!virt_dev->cdrom_empty) {
+		res->fd = vdev_open_fd(virt_dev);
+		if (IS_ERR(res->fd)) {
+			PRINT_ERROR("filp_open(%s) returned an error %ld",
+				virt_dev->filename, PTR_ERR(res->fd));
+			goto out_free;
+		}
+		if (virt_dev->blockio)
+			res->bdev = res->fd->f_dentry->d_inode->i_bdev;
+		else
+			res->bdev = NULL;
+	} else
+		res->fd = NULL;
+
+	scst_add_thr_data(tgt_dev, &res->hdr, vdisk_free_thr_data);
+
+out:
+	return res;
+
+out_free:
+	kmem_cache_free(vdisk_thr_cachep, res);
+	res = NULL;
+	goto out;
+}
+
+static int vdisk_attach_tgt(struct scst_tgt_dev *tgt_dev)
+{
+	int res = 0;
+
+	/* Nothing to do */
+	return res;
+}
+
+static void vdisk_detach_tgt(struct scst_tgt_dev *tgt_dev)
+{
+
+	scst_del_all_thr_data(tgt_dev);
+	return;
+}
+
+static int vdisk_do_job(struct scst_cmd *cmd)
+{
+	int rc, res;
+	uint64_t lba_start = 0;
+	loff_t data_len = 0;
+	uint8_t *cdb = cmd->cdb;
+	int opcode = cdb[0];
+	loff_t loff;
+	struct scst_device *dev = cmd->dev;
+	struct scst_tgt_dev *tgt_dev = cmd->tgt_dev;
+	struct scst_vdisk_dev *virt_dev =
+		(struct scst_vdisk_dev *)dev->dh_priv;
+	struct scst_thr_data_hdr *d;
+	struct scst_vdisk_thr *thr = NULL;
+	int fua = 0;
+
+	switch (cmd->queue_type) {
+	case SCST_CMD_QUEUE_ORDERED:
+		TRACE(TRACE_ORDER, "ORDERED cmd %p (op %x)", cmd, cmd->cdb[0]);
+		break;
+	case SCST_CMD_QUEUE_HEAD_OF_QUEUE:
+		TRACE(TRACE_ORDER, "HQ cmd %p (op %x)", cmd, cmd->cdb[0]);
+		break;
+	default:
+		break;
+	}
+
+	rc = scst_check_local_events(cmd);
+	if (unlikely(rc != 0))
+		goto out_done;
+
+	cmd->status = 0;
+	cmd->msg_status = 0;
+	cmd->host_status = DID_OK;
+	cmd->driver_status = 0;
+
+	if (!virt_dev->nullio) {
+		d = scst_find_thr_data(tgt_dev);
+		if (unlikely(d == NULL)) {
+			thr = vdisk_init_thr_data(tgt_dev);
+			if (thr == NULL) {
+				scst_set_busy(cmd);
+				goto out_compl;
+			}
+			scst_thr_data_get(&thr->hdr);
+		} else
+			thr = container_of(d, struct scst_vdisk_thr, hdr);
+	} else {
+		thr = &nullio_thr_data;
+		scst_thr_data_get(&thr->hdr);
+	}
+
+	switch (opcode) {
+	case READ_6:
+	case WRITE_6:
+	case VERIFY_6:
+		lba_start = (((cdb[1] & 0x1f) << (BYTE * 2)) +
+			     (cdb[2] << (BYTE * 1)) +
+			     (cdb[3] << (BYTE * 0)));
+		data_len = cmd->bufflen;
+		break;
+	case READ_10:
+	case READ_12:
+	case WRITE_10:
+	case WRITE_12:
+	case VERIFY:
+	case WRITE_VERIFY:
+	case WRITE_VERIFY_12:
+	case VERIFY_12:
+		lba_start |= ((u64)cdb[2]) << 24;
+		lba_start |= ((u64)cdb[3]) << 16;
+		lba_start |= ((u64)cdb[4]) << 8;
+		lba_start |= ((u64)cdb[5]);
+		data_len = cmd->bufflen;
+		break;
+	case READ_16:
+	case WRITE_16:
+	case WRITE_VERIFY_16:
+	case VERIFY_16:
+		lba_start |= ((u64)cdb[2]) << 56;
+		lba_start |= ((u64)cdb[3]) << 48;
+		lba_start |= ((u64)cdb[4]) << 40;
+		lba_start |= ((u64)cdb[5]) << 32;
+		lba_start |= ((u64)cdb[6]) << 24;
+		lba_start |= ((u64)cdb[7]) << 16;
+		lba_start |= ((u64)cdb[8]) << 8;
+		lba_start |= ((u64)cdb[9]);
+		data_len = cmd->bufflen;
+		break;
+	case SYNCHRONIZE_CACHE:
+		lba_start |= ((u64)cdb[2]) << 24;
+		lba_start |= ((u64)cdb[3]) << 16;
+		lba_start |= ((u64)cdb[4]) << 8;
+		lba_start |= ((u64)cdb[5]);
+		data_len = ((cdb[7] << (BYTE * 1)) + (cdb[8] << (BYTE * 0)))
+				<< virt_dev->block_shift;
+		if (data_len == 0)
+			data_len = virt_dev->file_size -
+				((loff_t)lba_start << virt_dev->block_shift);
+		break;
+	}
+
+	loff = (loff_t)lba_start << virt_dev->block_shift;
+	TRACE_DBG("cmd %p, lba_start %lld, loff %lld, data_len %lld", cmd,
+		  (long long unsigned int)lba_start,
+		  (long long unsigned int)loff,
+		  (long long unsigned int)data_len);
+	if (unlikely(loff < 0) || unlikely(data_len < 0) ||
+	    unlikely((loff + data_len) > virt_dev->file_size)) {
+		PRINT_INFO("Access beyond the end of the device "
+			"(%lld of %lld, len %lld)",
+			   (long long unsigned int)loff,
+			   (long long unsigned int)virt_dev->file_size,
+			   (long long unsigned int)data_len);
+		scst_set_cmd_error(cmd, SCST_LOAD_SENSE(
+					scst_sense_block_out_range_error));
+		goto out_compl;
+	}
+
+	switch (opcode) {
+	case WRITE_10:
+	case WRITE_12:
+	case WRITE_16:
+		fua = (cdb[1] & 0x8);
+		if (fua) {
+			TRACE(TRACE_ORDER, "FUA: loff=%lld, "
+				"data_len=%lld", (long long unsigned int)loff,
+				(long long unsigned int)data_len);
+		}
+		break;
+	}
+
+	switch (opcode) {
+	case READ_6:
+	case READ_10:
+	case READ_12:
+	case READ_16:
+		if (virt_dev->blockio) {
+			blockio_exec_rw(cmd, thr, lba_start, 0);
+			goto out_thr;
+		} else
+			vdisk_exec_read(cmd, thr, loff);
+		break;
+	case WRITE_6:
+	case WRITE_10:
+	case WRITE_12:
+	case WRITE_16:
+	{
+		if (virt_dev->blockio) {
+			blockio_exec_rw(cmd, thr, lba_start, 1);
+			goto out_thr;
+		} else
+			vdisk_exec_write(cmd, thr, loff);
+		/* O_SYNC flag is used for WT devices */
+		if (fua)
+			vdisk_fsync(thr, loff, data_len, cmd, dev);
+		break;
+	}
+	case WRITE_VERIFY:
+	case WRITE_VERIFY_12:
+	case WRITE_VERIFY_16:
+	{
+		/* ToDo: BLOCKIO VERIFY */
+		vdisk_exec_write(cmd, thr, loff);
+		/* O_SYNC flag is used for WT devices */
+		if (scsi_status_is_good(cmd->status))
+			vdisk_exec_verify(cmd, thr, loff);
+		break;
+	}
+	case SYNCHRONIZE_CACHE:
+	{
+		int immed = cdb[1] & 0x2;
+		TRACE(TRACE_ORDER, "SYNCHRONIZE_CACHE: "
+			"loff=%lld, data_len=%lld, immed=%d",
+			(long long unsigned int)loff,
+			(long long unsigned int)data_len, immed);
+		if (immed) {
+			scst_cmd_get(cmd); /* to protect dev */
+			cmd->completed = 1;
+			cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT,
+				SCST_CONTEXT_SAME);
+			vdisk_fsync(thr, loff, data_len, NULL, dev);
+			/* ToDo: vdisk_fsync() error processing */
+			scst_cmd_put(cmd);
+			goto out_thr;
+		} else {
+			vdisk_fsync(thr, loff, data_len, cmd, dev);
+			break;
+		}
+	}
+	case VERIFY_6:
+	case VERIFY:
+	case VERIFY_12:
+	case VERIFY_16:
+		vdisk_exec_verify(cmd, thr, loff);
+		break;
+	case MODE_SENSE:
+	case MODE_SENSE_10:
+		vdisk_exec_mode_sense(cmd);
+		break;
+	case MODE_SELECT:
+	case MODE_SELECT_10:
+		vdisk_exec_mode_select(cmd);
+		break;
+	case LOG_SELECT:
+	case LOG_SENSE:
+		vdisk_exec_log(cmd);
+		break;
+	case ALLOW_MEDIUM_REMOVAL:
+		vdisk_exec_prevent_allow_medium_removal(cmd);
+		break;
+	case READ_TOC:
+		vdisk_exec_read_toc(cmd);
+		break;
+	case START_STOP:
+		vdisk_fsync(thr, 0, virt_dev->file_size, cmd, dev);
+		break;
+	case RESERVE:
+	case RESERVE_10:
+	case RELEASE:
+	case RELEASE_10:
+	case TEST_UNIT_READY:
+		break;
+	case INQUIRY:
+		vdisk_exec_inquiry(cmd);
+		break;
+	case REQUEST_SENSE:
+		vdisk_exec_request_sense(cmd);
+		break;
+	case READ_CAPACITY:
+		vdisk_exec_read_capacity(cmd);
+		break;
+	case SERVICE_ACTION_IN:
+		if ((cmd->cdb[1] & 0x1f) == SAI_READ_CAPACITY_16) {
+			vdisk_exec_read_capacity16(cmd);
+			break;
+		}
+	case UNMAP:
+		vdisk_exec_unmap(cmd, thr);
+		break;
+		/* else go through */
+	case REPORT_LUNS:
+	default:
+		TRACE_DBG("Invalid opcode %d", opcode);
+		scst_set_cmd_error(cmd,
+		    SCST_LOAD_SENSE(scst_sense_invalid_opcode));
+	}
+
+out_compl:
+	cmd->completed = 1;
+
+out_done:
+	cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT, SCST_CONTEXT_SAME);
+
+out_thr:
+	if (likely(thr != NULL))
+		scst_thr_data_put(&thr->hdr);
+
+	res = SCST_EXEC_COMPLETED;
+	return res;
+}
+
+static int vdisk_get_block_shift(struct scst_cmd *cmd)
+{
+	struct scst_vdisk_dev *virt_dev =
+	    (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	return virt_dev->block_shift;
+}
+
+static int vdisk_parse(struct scst_cmd *cmd)
+{
+	scst_sbc_generic_parse(cmd, vdisk_get_block_shift);
+	return SCST_CMD_STATE_DEFAULT;
+}
+
+static int vcdrom_parse(struct scst_cmd *cmd)
+{
+	scst_cdrom_generic_parse(cmd, vdisk_get_block_shift);
+	return SCST_CMD_STATE_DEFAULT;
+}
+
+static int vcdrom_exec(struct scst_cmd *cmd)
+{
+	int res = SCST_EXEC_COMPLETED;
+	int opcode = cmd->cdb[0];
+	struct scst_vdisk_dev *virt_dev =
+	    (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+
+	cmd->status = 0;
+	cmd->msg_status = 0;
+	cmd->host_status = DID_OK;
+	cmd->driver_status = 0;
+
+	if (virt_dev->cdrom_empty && (opcode != INQUIRY)) {
+		TRACE_DBG("%s", "CDROM empty");
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_not_ready));
+		goto out_done;
+	}
+
+	if (virt_dev->media_changed && scst_is_ua_command(cmd)) {
+		spin_lock(&virt_dev->flags_lock);
+		if (virt_dev->media_changed) {
+			virt_dev->media_changed = 0;
+			TRACE_DBG("%s", "Reporting media changed");
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_medium_changed_UA));
+			spin_unlock(&virt_dev->flags_lock);
+			goto out_done;
+		}
+		spin_unlock(&virt_dev->flags_lock);
+	}
+
+	res = vdisk_do_job(cmd);
+
+out:
+	return res;
+
+out_done:
+	cmd->scst_cmd_done(cmd, SCST_CMD_STATE_DEFAULT, SCST_CONTEXT_SAME);
+	goto out;
+}
+
+static uint64_t vdisk_gen_dev_id_num(const char *virt_dev_name)
+{
+	unsigned int dev_id_num, i;
+
+	for (dev_id_num = 0, i = 0; i < strlen(virt_dev_name); i++) {
+		unsigned int rv = random_values[(int)(virt_dev_name[i])];
+		/* Do some rotating of the bits */
+		dev_id_num ^= ((rv << i) | (rv >> (32 - i)));
+	}
+
+	return ((uint64_t)scst_get_setup_id() << 32) | dev_id_num;
+}
+
+static void vdisk_exec_unmap(struct scst_cmd *cmd, struct scst_vdisk_thr *thr)
+{
+	struct scst_vdisk_dev *virt_dev =
+	    (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	ssize_t length = 0;
+	struct file *fd = thr->fd;
+	struct inode *inode;
+	uint8_t *address;
+	int offset, descriptor_len, total_len;
+
+	if (unlikely(virt_dev->thin_provisioned)) {
+		TRACE_DBG("%s", "Invalid opcode UNMAP");
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_opcode));
+		goto out;
+	}
+
+	length = scst_get_full_buf(cmd, &address);
+	if (unlikely(length <= 0)) {
+		if (length == 0)
+			goto out_put;
+		else if (length == -ENOMEM)
+			scst_set_busy(cmd);
+		else
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+		goto out;
+	}
+
+	inode = fd->f_dentry->d_inode;
+
+	total_len = cmd->cdb[7] << 8 | cmd->cdb[8]; /* length */
+	offset = 8;
+
+	descriptor_len = address[2] << 8 | address[3];
+
+	TRACE_DBG("total_len %d, descriptor_len %d", total_len, descriptor_len);
+
+	if (descriptor_len == 0)
+		goto out_put;
+
+	if (unlikely((descriptor_len > (total_len - 8)) ||
+		     ((descriptor_len % 16) != 0))) {
+		PRINT_ERROR("Bad descriptor length: %d < %d - 8",
+			descriptor_len, total_len);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_field_in_parm_list));
+		goto out_put;
+	}
+
+	while ((offset - 8) < descriptor_len) {
+		int err;
+		uint64_t start;
+		uint32_t len;
+		start = be64_to_cpu(get_unaligned((__be64 *)&address[offset]));
+		offset += 8;
+		len = be32_to_cpu(get_unaligned((__be32 *)&address[offset]));
+		offset += 8;
+
+		if ((start > virt_dev->nblocks) ||
+		    ((start + len) > virt_dev->nblocks)) {
+			PRINT_ERROR("Device %s: attempt to write beyond max "
+				"size", virt_dev->name);
+			scst_set_cmd_error(cmd,
+			    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+			goto out_put;
+		}
+
+		TRACE_DBG("Unmapping lba %lld (blocks %d)",
+			(unsigned long long)start, len);
+
+		if (virt_dev->blockio) {
+			err = blkdev_issue_discard(inode->i_bdev, start, len,
+					GFP_KERNEL, BLKDEV_IFL_WAIT);
+			if (unlikely(err != 0)) {
+				PRINT_ERROR("blkdev_issue_discard() for "
+					"LBA %lld len %d failed with err %d",
+					(unsigned long long)start, len, err);
+				goto out_hw_err;
+			}
+		} else {
+			/*
+			 * We are guaranteed by thin_provisioned flag
+			 * that truncate_range is not NULL.
+			 */
+			inode->i_op->truncate_range(inode,
+				start, start + len);
+		}
+	}
+
+out_put:
+	scst_put_full_buf(cmd, address);
+
+out:
+	return;
+
+out_hw_err:
+	scst_set_cmd_error(cmd, SCST_LOAD_SENSE(scst_sense_write_error));
+	goto out_put;
+}
+
+static void vdisk_exec_inquiry(struct scst_cmd *cmd)
+{
+	int32_t length, i, resp_len = 0;
+	uint8_t *address;
+	uint8_t *buf;
+	struct scst_vdisk_dev *virt_dev =
+	    (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+
+	/* ToDo: Performance Boost:
+	 * 1. remove kzalloc, buf
+	 * 2. do all checks before touching *address
+	 * 3. zero *address
+	 * 4. write directly to *address
+	 */
+
+	buf = kzalloc(INQ_BUF_SZ, GFP_KERNEL);
+	if (buf == NULL) {
+		scst_set_busy(cmd);
+		goto out;
+	}
+
+	length = scst_get_buf_first(cmd, &address);
+	TRACE_DBG("length %d", length);
+	if (unlikely(length <= 0)) {
+		if (length < 0) {
+			PRINT_ERROR("scst_get_buf_first() failed: %d", length);
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+		}
+		goto out_free;
+	}
+
+	if (cmd->cdb[1] & CMDDT) {
+		TRACE_DBG("%s", "INQUIRY: CMDDT is unsupported");
+		scst_set_cmd_error(cmd,
+		    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out_put;
+	}
+
+	buf[0] = cmd->dev->type;      /* type dev */
+	if (virt_dev->removable)
+		buf[1] = 0x80;      /* removable */
+	/* Vital Product */
+	if (cmd->cdb[1] & EVPD) {
+		if (0 == cmd->cdb[2]) {
+			/* supported vital product data pages */
+			buf[3] = 3;
+			buf[4] = 0x0; /* this page */
+			buf[5] = 0x80; /* unit serial number */
+			buf[6] = 0x83; /* device identification */
+			if (virt_dev->dev->type == TYPE_DISK) {
+				buf[3] += 1;
+				buf[7] = 0xB0; /* block limits */
+				if (virt_dev->thin_provisioned) {
+					buf[3] += 1;
+					buf[8] = 0xB2; /* thin provisioning */
+				}
+			}
+			resp_len = buf[3] + 4;
+		} else if (0x80 == cmd->cdb[2]) {
+			/* unit serial number */
+			int usn_len = strlen(virt_dev->usn);
+			buf[1] = 0x80;
+			buf[3] = usn_len;
+			strncpy(&buf[4], virt_dev->usn, usn_len);
+			resp_len = buf[3] + 4;
+		} else if (0x83 == cmd->cdb[2]) {
+			/* device identification */
+			int num = 4;
+
+			buf[1] = 0x83;
+			/* T10 vendor identifier field format (faked) */
+			buf[num + 0] = 0x2;	/* ASCII */
+			buf[num + 1] = 0x1;	/* Vendor ID */
+			if (virt_dev->blockio)
+				memcpy(&buf[num + 4], SCST_BIO_VENDOR, 8);
+			else
+				memcpy(&buf[num + 4], SCST_FIO_VENDOR, 8);
+
+			read_lock_bh(&vdisk_t10_dev_id_rwlock);
+			i = strlen(virt_dev->t10_dev_id);
+			memcpy(&buf[num + 12], virt_dev->t10_dev_id, i);
+			read_unlock_bh(&vdisk_t10_dev_id_rwlock);
+
+			buf[num + 3] = 8 + i;
+			num += buf[num + 3];
+
+			num += 4;
+
+			/*
+			 * Relative target port identifier
+			 */
+			buf[num + 0] = 0x01; /* binary */
+			/* Relative target port id */
+			buf[num + 1] = 0x10 | 0x04;
+
+			put_unaligned(cpu_to_be16(cmd->tgt->rel_tgt_id),
+				(__be16 *)&buf[num + 4 + 2]);
+
+			buf[num + 3] = 4;
+			num += buf[num + 3];
+
+			num += 4;
+
+			/*
+			 * IEEE id
+			 */
+			buf[num + 0] = 0x01; /* binary */
+
+			/* EUI-64 */
+			buf[num + 1] = 0x02;
+			buf[num + 2] = 0x00;
+			buf[num + 3] = 0x08;
+
+			/* IEEE id */
+			buf[num + 4] = virt_dev->t10_dev_id[0];
+			buf[num + 5] = virt_dev->t10_dev_id[1];
+			buf[num + 6] = virt_dev->t10_dev_id[2];
+
+			/* IEEE ext id */
+			buf[num + 7] = virt_dev->t10_dev_id[3];
+			buf[num + 8] = virt_dev->t10_dev_id[4];
+			buf[num + 9] = virt_dev->t10_dev_id[5];
+			buf[num + 10] = virt_dev->t10_dev_id[6];
+			buf[num + 11] = virt_dev->t10_dev_id[7];
+			num += buf[num + 3];
+
+			resp_len = num;
+			buf[2] = (resp_len >> 8) & 0xFF;
+			buf[3] = resp_len & 0xFF;
+			resp_len += 4;
+		} else if ((0xB0 == cmd->cdb[2]) &&
+			   (virt_dev->dev->type == TYPE_DISK)) {
+			/* Block Limits */
+			int max_transfer;
+			buf[1] = 0xB0;
+			buf[3] = 0x3C;
+			/* Optimal transfer granuality is PAGE_SIZE */
+			put_unaligned(cpu_to_be16(max_t(int,
+					PAGE_SIZE/virt_dev->block_size, 1)),
+				      (uint16_t *)&buf[6]);
+			/* Max transfer len is min of sg limit and 8M */
+			max_transfer = min_t(int,
+					cmd->tgt_dev->max_sg_cnt << PAGE_SHIFT,
+					8*1024*1024) / virt_dev->block_size;
+			put_unaligned(cpu_to_be32(max_transfer),
+					(uint32_t *)&buf[8]);
+			/*
+			 * Let's have optimal transfer len 1MB. Better to not
+			 * set it at all, because we don't have such limit,
+			 * but some initiators may not understand that (?).
+			 * From other side, too big transfers  are not optimal,
+			 * because SGV cache supports only <4M buffers.
+			 */
+			put_unaligned(cpu_to_be32(min_t(int,
+					max_transfer,
+					1*1024*1024 / virt_dev->block_size)),
+				      (uint32_t *)&buf[12]);
+			if (virt_dev->thin_provisioned) {
+				/* MAXIMUM UNMAP LBA COUNT is UNLIMITED */
+				put_unaligned(cpu_to_be32(0xFFFFFFFF),
+					      (uint16_t *)&buf[20]);
+				/* MAXIMUM UNMAP BLOCK DESCRIPTOR COUNT is UNLIMITED */
+				put_unaligned(cpu_to_be32(0xFFFFFFFF),
+					      (uint16_t *)&buf[24]);
+			}
+			resp_len = buf[3] + 4;
+		} else if ((0xB2 == cmd->cdb[2]) &&
+			   (virt_dev->dev->type == TYPE_DISK) &&
+			   virt_dev->thin_provisioned) {
+			/* Thin Provisioning */
+			buf[1] = 0xB2;
+			buf[3] = 2;
+			buf[5] = 0x80;
+			resp_len = buf[3] + 4;
+		} else {
+			TRACE_DBG("INQUIRY: Unsupported EVPD page %x",
+				cmd->cdb[2]);
+			scst_set_cmd_error(cmd,
+			    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+			goto out_put;
+		}
+	} else {
+		int len, num;
+
+		if (cmd->cdb[2] != 0) {
+			TRACE_DBG("INQUIRY: Unsupported page %x", cmd->cdb[2]);
+			scst_set_cmd_error(cmd,
+			    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+			goto out_put;
+		}
+
+		buf[2] = 5; /* Device complies to SPC-3 */
+		buf[3] = 0x12;	/* HiSup + data in format specified in SPC */
+		buf[4] = 31;/* n - 4 = 35 - 4 = 31 for full 36 byte data */
+		buf[6] = 1; /* MultiP 1 */
+		buf[7] = 2; /* CMDQUE 1, BQue 0 => commands queuing supported */
+
+		/*
+		 * 8 byte ASCII Vendor Identification of the target
+		 * - left aligned.
+		 */
+		if (virt_dev->blockio)
+			memcpy(&buf[8], SCST_BIO_VENDOR, 8);
+		else
+			memcpy(&buf[8], SCST_FIO_VENDOR, 8);
+
+		/*
+		 * 16 byte ASCII Product Identification of the target - left
+		 * aligned.
+		 */
+		memset(&buf[16], ' ', 16);
+		len = min(strlen(virt_dev->name), (size_t)16);
+		memcpy(&buf[16], virt_dev->name, len);
+
+		/*
+		 * 4 byte ASCII Product Revision Level of the target - left
+		 * aligned.
+		 */
+		memcpy(&buf[32], SCST_FIO_REV, 4);
+
+		/** Version descriptors **/
+
+		buf[4] += 58 - 36;
+		num = 0;
+
+		/* SAM-3 T10/1561-D revision 14 */
+		buf[58 + num] = 0x0;
+		buf[58 + num + 1] = 0x76;
+		num += 2;
+
+		/* Physical transport */
+		if (cmd->tgtt->get_phys_transport_version != NULL) {
+			uint16_t v = cmd->tgtt->get_phys_transport_version(cmd->tgt);
+			if (v != 0) {
+				*((__be16 *)&buf[58 + num]) = cpu_to_be16(v);
+				num += 2;
+			}
+		}
+
+		/* SCSI transport */
+		if (cmd->tgtt->get_scsi_transport_version != NULL) {
+			*((__be16 *)&buf[58 + num]) =
+				cpu_to_be16(cmd->tgtt->get_scsi_transport_version(cmd->tgt));
+			num += 2;
+		}
+
+		/* SPC-3 T10/1416-D revision 23 */
+		buf[58 + num] = 0x3;
+		buf[58 + num + 1] = 0x12;
+		num += 2;
+
+		/* Device command set */
+		if (virt_dev->command_set_version != 0) {
+			*((__be16 *)&buf[58 + num]) =
+				cpu_to_be16(virt_dev->command_set_version);
+			num += 2;
+		}
+
+		buf[4] += num;
+		resp_len = buf[4] + 5;
+	}
+
+	BUG_ON(resp_len >= INQ_BUF_SZ);
+
+	if (length > resp_len)
+		length = resp_len;
+	memcpy(address, buf, length);
+
+out_put:
+	scst_put_buf(cmd, address);
+	if (length < cmd->resp_data_len)
+		scst_set_resp_data_len(cmd, length);
+
+out_free:
+	kfree(buf);
+
+out:
+	return;
+}
+
+static void vdisk_exec_request_sense(struct scst_cmd *cmd)
+{
+	int32_t length, sl;
+	uint8_t *address;
+	uint8_t b[SCST_STANDARD_SENSE_LEN];
+
+	sl = scst_set_sense(b, sizeof(b), cmd->dev->d_sense,
+		SCST_LOAD_SENSE(scst_sense_no_sense));
+
+	length = scst_get_buf_first(cmd, &address);
+	TRACE_DBG("length %d", length);
+	if (length < 0) {
+		PRINT_ERROR("scst_get_buf_first() failed: %d)", length);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_hardw_error));
+		goto out;
+	}
+
+	length = min(sl, length);
+	memcpy(address, b, length);
+	scst_set_resp_data_len(cmd, length);
+
+	scst_put_buf(cmd, address);
+
+out:
+	return;
+}
+
+/*
+ * <<Following mode pages info copied from ST318451LW with some corrections>>
+ *
+ * ToDo: revise them
+ */
+static int vdisk_err_recov_pg(unsigned char *p, int pcontrol,
+			       struct scst_vdisk_dev *virt_dev)
+{	/* Read-Write Error Recovery page for mode_sense */
+	const unsigned char err_recov_pg[] = {0x1, 0xa, 0xc0, 11, 240, 0, 0, 0,
+					      5, 0, 0xff, 0xff};
+
+	memcpy(p, err_recov_pg, sizeof(err_recov_pg));
+	if (1 == pcontrol)
+		memset(p + 2, 0, sizeof(err_recov_pg) - 2);
+	return sizeof(err_recov_pg);
+}
+
+static int vdisk_disconnect_pg(unsigned char *p, int pcontrol,
+				struct scst_vdisk_dev *virt_dev)
+{	/* Disconnect-Reconnect page for mode_sense */
+	const unsigned char disconnect_pg[] = {0x2, 0xe, 128, 128, 0, 10, 0, 0,
+					       0, 0, 0, 0, 0, 0, 0, 0};
+
+	memcpy(p, disconnect_pg, sizeof(disconnect_pg));
+	if (1 == pcontrol)
+		memset(p + 2, 0, sizeof(disconnect_pg) - 2);
+	return sizeof(disconnect_pg);
+}
+
+static int vdisk_rigid_geo_pg(unsigned char *p, int pcontrol,
+	struct scst_vdisk_dev *virt_dev)
+{
+	unsigned char geo_m_pg[] = {0x04, 0x16, 0, 0, 0, DEF_HEADS, 0, 0,
+				    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+				    0x3a, 0x98/* 15K RPM */, 0, 0};
+	int32_t ncyl, n, rem;
+	uint64_t dividend;
+
+	memcpy(p, geo_m_pg, sizeof(geo_m_pg));
+	/*
+	 * Divide virt_dev->nblocks by (DEF_HEADS * DEF_SECTORS) and store
+	 * the quotient in ncyl and the remainder in rem.
+	 */
+	dividend = virt_dev->nblocks;
+	rem = do_div(dividend, DEF_HEADS * DEF_SECTORS);
+	ncyl = dividend;
+	if (rem != 0)
+		ncyl++;
+	memcpy(&n, p + 2, sizeof(u32));
+	n = n | ((__force u32)cpu_to_be32(ncyl) >> 8);
+	memcpy(p + 2, &n, sizeof(u32));
+	if (1 == pcontrol)
+		memset(p + 2, 0, sizeof(geo_m_pg) - 2);
+	return sizeof(geo_m_pg);
+}
+
+static int vdisk_format_pg(unsigned char *p, int pcontrol,
+			    struct scst_vdisk_dev *virt_dev)
+{       /* Format device page for mode_sense */
+	const unsigned char format_pg[] = {0x3, 0x16, 0, 0, 0, 0, 0, 0,
+					   0, 0, 0, 0, 0, 0, 0, 0,
+					   0, 0, 0, 0, 0x40, 0, 0, 0};
+
+	memcpy(p, format_pg, sizeof(format_pg));
+	p[10] = (DEF_SECTORS >> 8) & 0xff;
+	p[11] = DEF_SECTORS & 0xff;
+	p[12] = (virt_dev->block_size >> 8) & 0xff;
+	p[13] = virt_dev->block_size & 0xff;
+	if (1 == pcontrol)
+		memset(p + 2, 0, sizeof(format_pg) - 2);
+	return sizeof(format_pg);
+}
+
+static int vdisk_caching_pg(unsigned char *p, int pcontrol,
+			     struct scst_vdisk_dev *virt_dev)
+{	/* Caching page for mode_sense */
+	const unsigned char caching_pg[] = {0x8, 18, 0x10, 0, 0xff, 0xff, 0, 0,
+		0xff, 0xff, 0xff, 0xff, 0x80, 0x14, 0, 0, 0, 0, 0, 0};
+
+	memcpy(p, caching_pg, sizeof(caching_pg));
+	p[2] |= !(virt_dev->wt_flag || virt_dev->nv_cache) ? WCE : 0;
+	if (1 == pcontrol)
+		memset(p + 2, 0, sizeof(caching_pg) - 2);
+	return sizeof(caching_pg);
+}
+
+static int vdisk_ctrl_m_pg(unsigned char *p, int pcontrol,
+			    struct scst_vdisk_dev *virt_dev)
+{	/* Control mode page for mode_sense */
+	const unsigned char ctrl_m_pg[] = {0xa, 0xa, 0, 0, 0, 0, 0, 0,
+					   0, 0, 0x2, 0x4b};
+
+	memcpy(p, ctrl_m_pg, sizeof(ctrl_m_pg));
+	switch (pcontrol) {
+	case 0:
+		p[2] |= virt_dev->dev->tst << 5;
+		p[2] |= virt_dev->dev->d_sense << 2;
+		p[3] |= virt_dev->dev->queue_alg << 4;
+		p[4] |= virt_dev->dev->swp << 3;
+		p[5] |= virt_dev->dev->tas << 6;
+		break;
+	case 1:
+		memset(p + 2, 0, sizeof(ctrl_m_pg) - 2);
+#if 0	/*
+	 * It's too early to implement it, since we can't control the
+	 * backstorage device parameters. ToDo
+	 */
+		p[2] |= 7 << 5;		/* TST */
+		p[3] |= 0xF << 4;	/* QUEUE ALGORITHM MODIFIER */
+#endif
+		p[2] |= 1 << 2;		/* D_SENSE */
+		p[4] |= 1 << 3;		/* SWP */
+		p[5] |= 1 << 6;		/* TAS */
+		break;
+	case 2:
+		p[2] |= DEF_TST << 5;
+		p[2] |= DEF_DSENSE << 2;
+		if (virt_dev->wt_flag || virt_dev->nv_cache)
+			p[3] |= DEF_QUEUE_ALG_WT << 4;
+		else
+			p[3] |= DEF_QUEUE_ALG << 4;
+		p[4] |= DEF_SWP << 3;
+		p[5] |= DEF_TAS << 6;
+		break;
+	default:
+		BUG();
+	}
+	return sizeof(ctrl_m_pg);
+}
+
+static int vdisk_iec_m_pg(unsigned char *p, int pcontrol,
+			   struct scst_vdisk_dev *virt_dev)
+{	/* Informational Exceptions control mode page for mode_sense */
+	const unsigned char iec_m_pg[] = {0x1c, 0xa, 0x08, 0, 0, 0, 0, 0,
+					  0, 0, 0x0, 0x0};
+	memcpy(p, iec_m_pg, sizeof(iec_m_pg));
+	if (1 == pcontrol)
+		memset(p + 2, 0, sizeof(iec_m_pg) - 2);
+	return sizeof(iec_m_pg);
+}
+
+static void vdisk_exec_mode_sense(struct scst_cmd *cmd)
+{
+	int32_t length;
+	uint8_t *address;
+	uint8_t *buf;
+	struct scst_vdisk_dev *virt_dev;
+	uint32_t blocksize;
+	uint64_t nblocks;
+	unsigned char dbd, type;
+	int pcontrol, pcode, subpcode;
+	unsigned char dev_spec;
+	int msense_6, offset = 0, len;
+	unsigned char *bp;
+
+	buf = kzalloc(MSENSE_BUF_SZ, GFP_KERNEL);
+	if (buf == NULL) {
+		scst_set_busy(cmd);
+		goto out;
+	}
+
+	virt_dev = (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	blocksize = virt_dev->block_size;
+	nblocks = virt_dev->nblocks;
+
+	type = cmd->dev->type;    /* type dev */
+	dbd = cmd->cdb[1] & DBD;
+	pcontrol = (cmd->cdb[2] & 0xc0) >> 6;
+	pcode = cmd->cdb[2] & 0x3f;
+	subpcode = cmd->cdb[3];
+	msense_6 = (MODE_SENSE == cmd->cdb[0]);
+	dev_spec = (virt_dev->dev->rd_only ||
+		     cmd->tgt_dev->acg_dev->rd_only) ? WP : 0;
+
+	if (!virt_dev->blockio)
+		dev_spec |= DPOFUA;
+
+	length = scst_get_buf_first(cmd, &address);
+	if (unlikely(length <= 0)) {
+		if (length < 0) {
+			PRINT_ERROR("scst_get_buf_first() failed: %d", length);
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+		}
+		goto out_free;
+	}
+
+	if (0x3 == pcontrol) {
+		TRACE_DBG("%s", "MODE SENSE: Saving values not supported");
+		scst_set_cmd_error(cmd,
+		    SCST_LOAD_SENSE(scst_sense_saving_params_unsup));
+		goto out_put;
+	}
+
+	if (msense_6) {
+		buf[1] = type;
+		buf[2] = dev_spec;
+		offset = 4;
+	} else {
+		buf[2] = type;
+		buf[3] = dev_spec;
+		offset = 8;
+	}
+
+	if (0 != subpcode) {
+		/* TODO: Control Extension page */
+		TRACE_DBG("%s", "MODE SENSE: Only subpage 0 is supported");
+		scst_set_cmd_error(cmd,
+		    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out_put;
+	}
+
+	if (!dbd) {
+		/* Create block descriptor */
+		buf[offset - 1] = 0x08;		/* block descriptor length */
+		if (nblocks >> 32) {
+			buf[offset + 0] = 0xFF;
+			buf[offset + 1] = 0xFF;
+			buf[offset + 2] = 0xFF;
+			buf[offset + 3] = 0xFF;
+		} else {
+			/* num blks */
+			buf[offset + 0] = (nblocks >> (BYTE * 3)) & 0xFF;
+			buf[offset + 1] = (nblocks >> (BYTE * 2)) & 0xFF;
+			buf[offset + 2] = (nblocks >> (BYTE * 1)) & 0xFF;
+			buf[offset + 3] = (nblocks >> (BYTE * 0)) & 0xFF;
+		}
+		buf[offset + 4] = 0;			/* density code */
+		buf[offset + 5] = (blocksize >> (BYTE * 2)) & 0xFF;/* blklen */
+		buf[offset + 6] = (blocksize >> (BYTE * 1)) & 0xFF;
+		buf[offset + 7] = (blocksize >> (BYTE * 0)) & 0xFF;
+
+		offset += 8;			/* increment offset */
+	}
+
+	bp = buf + offset;
+
+	switch (pcode) {
+	case 0x1:	/* Read-Write error recovery page, direct access */
+		len = vdisk_err_recov_pg(bp, pcontrol, virt_dev);
+		break;
+	case 0x2:	/* Disconnect-Reconnect page, all devices */
+		len = vdisk_disconnect_pg(bp, pcontrol, virt_dev);
+		break;
+	case 0x3:       /* Format device page, direct access */
+		len = vdisk_format_pg(bp, pcontrol, virt_dev);
+		break;
+	case 0x4:	/* Rigid disk geometry */
+		len = vdisk_rigid_geo_pg(bp, pcontrol, virt_dev);
+		break;
+	case 0x8:	/* Caching page, direct access */
+		len = vdisk_caching_pg(bp, pcontrol, virt_dev);
+		break;
+	case 0xa:	/* Control Mode page, all devices */
+		len = vdisk_ctrl_m_pg(bp, pcontrol, virt_dev);
+		break;
+	case 0x1c:	/* Informational Exceptions Mode page, all devices */
+		len = vdisk_iec_m_pg(bp, pcontrol, virt_dev);
+		break;
+	case 0x3f:	/* Read all Mode pages */
+		len = vdisk_err_recov_pg(bp, pcontrol, virt_dev);
+		len += vdisk_disconnect_pg(bp + len, pcontrol, virt_dev);
+		len += vdisk_format_pg(bp + len, pcontrol, virt_dev);
+		len += vdisk_caching_pg(bp + len, pcontrol, virt_dev);
+		len += vdisk_ctrl_m_pg(bp + len, pcontrol, virt_dev);
+		len += vdisk_iec_m_pg(bp + len, pcontrol, virt_dev);
+		len += vdisk_rigid_geo_pg(bp + len, pcontrol, virt_dev);
+		break;
+	default:
+		TRACE_DBG("MODE SENSE: Unsupported page %x", pcode);
+		scst_set_cmd_error(cmd,
+		    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out_put;
+	}
+
+	offset += len;
+
+	if (msense_6)
+		buf[0] = offset - 1;
+	else {
+		buf[0] = ((offset - 2) >> 8) & 0xff;
+		buf[1] = (offset - 2) & 0xff;
+	}
+
+	if (offset > length)
+		offset = length;
+	memcpy(address, buf, offset);
+
+out_put:
+	scst_put_buf(cmd, address);
+	if (offset < cmd->resp_data_len)
+		scst_set_resp_data_len(cmd, offset);
+
+out_free:
+	kfree(buf);
+
+out:
+	return;
+}
+
+static int vdisk_set_wt(struct scst_vdisk_dev *virt_dev, int wt)
+{
+	int res = 0;
+
+	if ((virt_dev->wt_flag == wt) || virt_dev->nullio || virt_dev->nv_cache)
+		goto out;
+
+	spin_lock(&virt_dev->flags_lock);
+	virt_dev->wt_flag = wt;
+	spin_unlock(&virt_dev->flags_lock);
+
+	scst_dev_del_all_thr_data(virt_dev->dev);
+
+out:
+	return res;
+}
+
+static void vdisk_ctrl_m_pg_select(unsigned char *p,
+	struct scst_vdisk_dev *virt_dev)
+{
+	struct scst_device *dev = virt_dev->dev;
+	int old_swp = dev->swp, old_tas = dev->tas, old_dsense = dev->d_sense;
+
+#if 0
+	/* Not implemented yet, see comment in vdisk_ctrl_m_pg() */
+	dev->tst = p[2] >> 5;
+	dev->queue_alg = p[3] >> 4;
+#endif
+	dev->swp = (p[4] & 0x8) >> 3;
+	dev->tas = (p[5] & 0x40) >> 6;
+	dev->d_sense = (p[2] & 0x4) >> 2;
+
+	PRINT_INFO("Device %s: new control mode page parameters: SWP %x "
+		"(was %x), TAS %x (was %x), D_SENSE %d (was %d)",
+		virt_dev->name, dev->swp, old_swp, dev->tas, old_tas,
+		dev->d_sense, old_dsense);
+	return;
+}
+
+static void vdisk_exec_mode_select(struct scst_cmd *cmd)
+{
+	int32_t length;
+	uint8_t *address;
+	struct scst_vdisk_dev *virt_dev;
+	int mselect_6, offset;
+
+	virt_dev = (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	mselect_6 = (MODE_SELECT == cmd->cdb[0]);
+
+	length = scst_get_buf_first(cmd, &address);
+	if (unlikely(length <= 0)) {
+		if (length < 0) {
+			PRINT_ERROR("scst_get_buf_first() failed: %d", length);
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+		}
+		goto out;
+	}
+
+	if (!(cmd->cdb[1] & PF) || (cmd->cdb[1] & SP)) {
+		TRACE(TRACE_MINOR|TRACE_SCSI, "MODE SELECT: Unsupported "
+			"value(s) of PF and/or SP bits (cdb[1]=%x)",
+			cmd->cdb[1]);
+		scst_set_cmd_error(cmd,
+		    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out_put;
+	}
+
+	if (mselect_6)
+		offset = 4;
+	else
+		offset = 8;
+
+	if (address[offset - 1] == 8) {
+		offset += 8;
+	} else if (address[offset - 1] != 0) {
+		PRINT_ERROR("%s", "MODE SELECT: Wrong parameters list "
+			"lenght");
+		scst_set_cmd_error(cmd,
+		    SCST_LOAD_SENSE(scst_sense_invalid_field_in_parm_list));
+		goto out_put;
+	}
+
+	while (length > offset + 2) {
+		if (address[offset] & PS) {
+			PRINT_ERROR("%s", "MODE SELECT: Illegal PS bit");
+			scst_set_cmd_error(cmd, SCST_LOAD_SENSE(
+				scst_sense_invalid_field_in_parm_list));
+			goto out_put;
+		}
+		if ((address[offset] & 0x3f) == 0x8) {
+			/* Caching page */
+			if (address[offset + 1] != 18) {
+				PRINT_ERROR("%s", "MODE SELECT: Invalid "
+					"caching page request");
+				scst_set_cmd_error(cmd, SCST_LOAD_SENSE(
+				    scst_sense_invalid_field_in_parm_list));
+				goto out_put;
+			}
+			if (vdisk_set_wt(virt_dev,
+			      (address[offset + 2] & WCE) ? 0 : 1) != 0) {
+				scst_set_cmd_error(cmd,
+				    SCST_LOAD_SENSE(scst_sense_hardw_error));
+				goto out_put;
+			}
+			break;
+		} else if ((address[offset] & 0x3f) == 0xA) {
+			/* Control page */
+			if (address[offset + 1] != 0xA) {
+				PRINT_ERROR("%s", "MODE SELECT: Invalid "
+					"control page request");
+				scst_set_cmd_error(cmd, SCST_LOAD_SENSE(
+				    scst_sense_invalid_field_in_parm_list));
+				goto out_put;
+			}
+			vdisk_ctrl_m_pg_select(&address[offset], virt_dev);
+		} else {
+			PRINT_ERROR("MODE SELECT: Invalid request %x",
+				address[offset] & 0x3f);
+			scst_set_cmd_error(cmd, SCST_LOAD_SENSE(
+			    scst_sense_invalid_field_in_parm_list));
+			goto out_put;
+		}
+		offset += address[offset + 1];
+	}
+
+out_put:
+	scst_put_buf(cmd, address);
+
+out:
+	return;
+}
+
+static void vdisk_exec_log(struct scst_cmd *cmd)
+{
+
+	/* No log pages are supported */
+	scst_set_cmd_error(cmd,
+		SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+	return;
+}
+
+static void vdisk_exec_read_capacity(struct scst_cmd *cmd)
+{
+	int32_t length;
+	uint8_t *address;
+	struct scst_vdisk_dev *virt_dev;
+	uint32_t blocksize;
+	uint64_t nblocks;
+	uint8_t buffer[8];
+
+	virt_dev = (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	blocksize = virt_dev->block_size;
+	nblocks = virt_dev->nblocks;
+
+	if ((cmd->cdb[8] & 1) == 0) {
+		uint64_t lba = be64_to_cpu(get_unaligned((__be64 *)&cmd->cdb[2]));
+		if (lba != 0) {
+			TRACE_DBG("PMI zero and LBA not zero (cmd %p)", cmd);
+			scst_set_cmd_error(cmd,
+			    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+			goto out;
+		}
+	}
+
+	/* Last block on the virt_dev is (nblocks-1) */
+	memset(buffer, 0, sizeof(buffer));
+
+	/*
+	 * If we are thinly provisioned, we must ensure that the initiator
+	 * issues a READ_CAPACITY(16) so we can return the TPE bit. By
+	 * returning 0xFFFFFFFF we do that.
+	 */
+	if (nblocks >> 32 || virt_dev->thin_provisioned) {
+		buffer[0] = 0xFF;
+		buffer[1] = 0xFF;
+		buffer[2] = 0xFF;
+		buffer[3] = 0xFF;
+	} else {
+		buffer[0] = ((nblocks - 1) >> (BYTE * 3)) & 0xFF;
+		buffer[1] = ((nblocks - 1) >> (BYTE * 2)) & 0xFF;
+		buffer[2] = ((nblocks - 1) >> (BYTE * 1)) & 0xFF;
+		buffer[3] = ((nblocks - 1) >> (BYTE * 0)) & 0xFF;
+	}
+	buffer[4] = (blocksize >> (BYTE * 3)) & 0xFF;
+	buffer[5] = (blocksize >> (BYTE * 2)) & 0xFF;
+	buffer[6] = (blocksize >> (BYTE * 1)) & 0xFF;
+	buffer[7] = (blocksize >> (BYTE * 0)) & 0xFF;
+
+	length = scst_get_buf_first(cmd, &address);
+	if (unlikely(length <= 0)) {
+		if (length < 0) {
+			PRINT_ERROR("scst_get_buf_first() failed: %d", length);
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+		}
+		goto out;
+	}
+
+	length = min_t(int, length, sizeof(buffer));
+
+	memcpy(address, buffer, length);
+
+	scst_put_buf(cmd, address);
+
+	if (length < cmd->resp_data_len)
+		scst_set_resp_data_len(cmd, length);
+
+out:
+	return;
+}
+
+static void vdisk_exec_read_capacity16(struct scst_cmd *cmd)
+{
+	int32_t length;
+	uint8_t *address;
+	struct scst_vdisk_dev *virt_dev;
+	uint32_t blocksize;
+	uint64_t nblocks;
+	uint8_t buffer[32];
+
+	virt_dev = (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	blocksize = virt_dev->block_size;
+	nblocks = virt_dev->nblocks - 1;
+
+	if ((cmd->cdb[14] & 1) == 0) {
+		uint64_t lba = be64_to_cpu(get_unaligned((__be64 *)&cmd->cdb[2]));
+		if (lba != 0) {
+			TRACE_DBG("PMI zero and LBA not zero (cmd %p)", cmd);
+			scst_set_cmd_error(cmd,
+			    SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+			goto out;
+		}
+	}
+
+	memset(buffer, 0, sizeof(buffer));
+
+	buffer[0] = nblocks >> 56;
+	buffer[1] = (nblocks >> 48) & 0xFF;
+	buffer[2] = (nblocks >> 40) & 0xFF;
+	buffer[3] = (nblocks >> 32) & 0xFF;
+	buffer[4] = (nblocks >> 24) & 0xFF;
+	buffer[5] = (nblocks >> 16) & 0xFF;
+	buffer[6] = (nblocks >> 8) & 0xFF;
+	buffer[7] = nblocks & 0xFF;
+
+	buffer[8] = (blocksize >> (BYTE * 3)) & 0xFF;
+	buffer[9] = (blocksize >> (BYTE * 2)) & 0xFF;
+	buffer[10] = (blocksize >> (BYTE * 1)) & 0xFF;
+	buffer[11] = (blocksize >> (BYTE * 0)) & 0xFF;
+
+	switch (blocksize) {
+	case 512:
+		buffer[13] = 3;
+		break;
+	case 1024:
+		buffer[13] = 2;
+		break;
+	case 2048:
+		buffer[13] = 1;
+		break;
+	case 4096:
+	default:
+		buffer[13] = 0;
+		break;
+	}
+
+	if (virt_dev->thin_provisioned)
+		buffer[14] |= 0x80;     /* Add TPE */
+
+	length = scst_get_buf_first(cmd, &address);
+	if (unlikely(length <= 0)) {
+		if (length < 0) {
+			PRINT_ERROR("scst_get_buf_first() failed: %d", length);
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+			}
+		goto out;
+	}
+
+	length = min_t(int, length, sizeof(buffer));
+
+	memcpy(address, buffer, length);
+
+	scst_put_buf(cmd, address);
+
+	if (length < cmd->resp_data_len)
+		scst_set_resp_data_len(cmd, length);
+
+out:
+	return;
+}
+
+static void vdisk_exec_read_toc(struct scst_cmd *cmd)
+{
+	int32_t length, off = 0;
+	uint8_t *address;
+	struct scst_vdisk_dev *virt_dev;
+	uint32_t nblocks;
+	uint8_t buffer[4+8+8] = { 0x00, 0x0a, 0x01, 0x01, 0x00, 0x14,
+				  0x01, 0x00, 0x00, 0x00, 0x00, 0x00 };
+
+	if (cmd->dev->type != TYPE_ROM) {
+		PRINT_ERROR("%s", "READ TOC for non-CDROM device");
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_opcode));
+		goto out;
+	}
+
+	if (cmd->cdb[2] & 0x0e/*Format*/) {
+		PRINT_ERROR("%s", "READ TOC: invalid requested data format");
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out;
+	}
+
+	if ((cmd->cdb[6] != 0 && (cmd->cdb[2] & 0x01)) ||
+	    (cmd->cdb[6] > 1 && cmd->cdb[6] != 0xAA)) {
+		PRINT_ERROR("READ TOC: invalid requested track number %x",
+			cmd->cdb[6]);
+		scst_set_cmd_error(cmd,
+			SCST_LOAD_SENSE(scst_sense_invalid_field_in_cdb));
+		goto out;
+	}
+
+	length = scst_get_buf_first(cmd, &address);
+	if (unlikely(length <= 0)) {
+		if (length < 0) {
+			PRINT_ERROR("scst_get_buf_first() failed: %d", length);
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+		}
+		goto out;
+	}
+
+	virt_dev = (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	/* ToDo when you have > 8TB ROM device. */
+	nblocks = (uint32_t)virt_dev->nblocks;
+
+	/* Header */
+	memset(buffer, 0, sizeof(buffer));
+	buffer[2] = 0x01;    /* First Track/Session */
+	buffer[3] = 0x01;    /* Last Track/Session */
+	off = 4;
+	if (cmd->cdb[6] <= 1) {
+		/* Fistr TOC Track Descriptor */
+		/* ADDR    0x10 - Q Sub-channel encodes current position data
+		   CONTROL 0x04 - Data track, recoreded uninterrupted */
+		buffer[off+1] = 0x14;
+		/* Track Number */
+		buffer[off+2] = 0x01;
+		off += 8;
+	}
+	if (!(cmd->cdb[2] & 0x01)) {
+		/* Lead-out area TOC Track Descriptor */
+		buffer[off+1] = 0x14;
+		/* Track Number */
+		buffer[off+2] = 0xAA;
+		/* Track Start Address */
+		buffer[off+4] = (nblocks >> (BYTE * 3)) & 0xFF;
+		buffer[off+5] = (nblocks >> (BYTE * 2)) & 0xFF;
+		buffer[off+6] = (nblocks >> (BYTE * 1)) & 0xFF;
+		buffer[off+7] = (nblocks >> (BYTE * 0)) & 0xFF;
+		off += 8;
+	}
+
+	buffer[1] = off - 2;    /* Data  Length */
+
+	if (off > length)
+		off = length;
+	memcpy(address, buffer, off);
+
+	scst_put_buf(cmd, address);
+
+	if (off < cmd->resp_data_len)
+		scst_set_resp_data_len(cmd, off);
+
+out:
+	return;
+}
+
+static void vdisk_exec_prevent_allow_medium_removal(struct scst_cmd *cmd)
+{
+	struct scst_vdisk_dev *virt_dev =
+		(struct scst_vdisk_dev *)cmd->dev->dh_priv;
+
+	TRACE_DBG("PERSIST/PREVENT 0x%02x", cmd->cdb[4]);
+
+	spin_lock(&virt_dev->flags_lock);
+	virt_dev->prevent_allow_medium_removal = cmd->cdb[4] & 0x01 ? 1 : 0;
+	spin_unlock(&virt_dev->flags_lock);
+
+	return;
+}
+
+static int vdisk_fsync(struct scst_vdisk_thr *thr, loff_t loff,
+	loff_t len, struct scst_cmd *cmd, struct scst_device *dev)
+{
+	int res = 0;
+	struct scst_vdisk_dev *virt_dev =
+		(struct scst_vdisk_dev *)dev->dh_priv;
+	struct file *file;
+
+	/* Hopefully, the compiler will generate the single comparison */
+	if (virt_dev->nv_cache || virt_dev->wt_flag ||
+	    virt_dev->o_direct_flag || virt_dev->nullio)
+		goto out;
+
+	if (virt_dev->blockio) {
+		res = blockio_flush(thr->bdev);
+		goto out;
+	}
+
+	file = thr->fd;
+
+#if 0	/* For sparse files we might need to sync metadata as well */
+	res = generic_write_sync(file, loff, len);
+#else
+	res = filemap_write_and_wait_range(file->f_mapping, loff, len);
+#endif
+	if (unlikely(res != 0)) {
+		PRINT_ERROR("sync range failed (%d)", res);
+		if (cmd != NULL) {
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_write_error));
+		}
+	}
+
+out:
+	return res;
+}
+
+static struct iovec *vdisk_alloc_iv(struct scst_cmd *cmd,
+	struct scst_vdisk_thr *thr)
+{
+	int iv_count;
+
+	iv_count = min_t(int, scst_get_buf_count(cmd), UIO_MAXIOV);
+	if (iv_count > thr->iv_count) {
+		kfree(thr->iv);
+		/* It can't be called in atomic context */
+		thr->iv = kmalloc(sizeof(*thr->iv) * iv_count, GFP_KERNEL);
+		if (thr->iv == NULL) {
+			PRINT_ERROR("Unable to allocate iv (%d)", iv_count);
+			scst_set_busy(cmd);
+			goto out;
+		}
+		thr->iv_count = iv_count;
+	}
+
+out:
+	return thr->iv;
+}
+
+static void vdisk_exec_read(struct scst_cmd *cmd,
+	struct scst_vdisk_thr *thr, loff_t loff)
+{
+	mm_segment_t old_fs;
+	loff_t err;
+	ssize_t length, full_len;
+	uint8_t __user *address;
+	struct scst_vdisk_dev *virt_dev =
+	    (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	struct file *fd = thr->fd;
+	struct iovec *iv;
+	int iv_count, i;
+	bool finished = false;
+
+	if (virt_dev->nullio)
+		goto out;
+
+	iv = vdisk_alloc_iv(cmd, thr);
+	if (iv == NULL)
+		goto out;
+
+	length = scst_get_buf_first(cmd, (uint8_t __force **)&address);
+	if (unlikely(length < 0)) {
+		PRINT_ERROR("scst_get_buf_first() failed: %zd", length);
+		scst_set_cmd_error(cmd,
+		    SCST_LOAD_SENSE(scst_sense_hardw_error));
+		goto out;
+	}
+
+	old_fs = get_fs();
+	set_fs(get_ds());
+
+	while (1) {
+		iv_count = 0;
+		full_len = 0;
+		i = -1;
+		while (length > 0) {
+			full_len += length;
+			i++;
+			iv_count++;
+			iv[i].iov_base = address;
+			iv[i].iov_len = length;
+			if (iv_count == UIO_MAXIOV)
+				break;
+			length = scst_get_buf_next(cmd,
+				(uint8_t __force **)&address);
+		}
+		if (length == 0) {
+			finished = true;
+			if (unlikely(iv_count == 0))
+				break;
+		} else if (unlikely(length < 0)) {
+			PRINT_ERROR("scst_get_buf_next() failed: %zd", length);
+			scst_set_cmd_error(cmd,
+			    SCST_LOAD_SENSE(scst_sense_hardw_error));
+			goto out_set_fs;
+		}
+
+		TRACE_DBG("(iv_count %d, full_len %zd)", iv_count, full_len);
+		/* SEEK */
+		if (fd->f_op->llseek)
+			err = fd->f_op->llseek(fd, loff, 0/*SEEK_SET*/);
+		else
+			err = default_llseek(fd, loff, 0/*SEEK_SET*/);
+		if (err != loff) {
+			PRINT_ERROR("lseek trouble %lld != %lld",
+				    (long long unsigned int)err,
+				    (long long unsigned int)loff);
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+			goto out_set_fs;
+		}
+
+		/* READ */
+		err = vfs_readv(fd, (struct iovec __force __user *)iv, iv_count,
+				&fd->f_pos);
+
+		if ((err < 0) || (err < full_len)) {
+			PRINT_ERROR("readv() returned %lld from %zd",
+				    (long long unsigned int)err,
+				    full_len);
+			if (err == -EAGAIN)
+				scst_set_busy(cmd);
+			else {
+				scst_set_cmd_error(cmd,
+				    SCST_LOAD_SENSE(scst_sense_read_error));
+			}
+			goto out_set_fs;
+		}
+
+		for (i = 0; i < iv_count; i++)
+			scst_put_buf(cmd, (void __force *)(iv[i].iov_base));
+
+		if (finished)
+			break;
+
+		loff += full_len;
+		length = scst_get_buf_next(cmd, (uint8_t __force **)&address);
+	};
+
+	set_fs(old_fs);
+
+out:
+	return;
+
+out_set_fs:
+	set_fs(old_fs);
+	for (i = 0; i < iv_count; i++)
+		scst_put_buf(cmd, (void __force *)(iv[i].iov_base));
+	goto out;
+}
+
+static void vdisk_exec_write(struct scst_cmd *cmd,
+	struct scst_vdisk_thr *thr, loff_t loff)
+{
+	mm_segment_t old_fs;
+	loff_t err;
+	ssize_t length, full_len, saved_full_len;
+	uint8_t __user *address;
+	struct scst_vdisk_dev *virt_dev =
+	    (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	struct file *fd = thr->fd;
+	struct iovec *iv, *eiv;
+	int i, iv_count, eiv_count;
+	bool finished = false;
+
+	if (virt_dev->nullio)
+		goto out;
+
+	iv = vdisk_alloc_iv(cmd, thr);
+	if (iv == NULL)
+		goto out;
+
+	length = scst_get_buf_first(cmd, (uint8_t __force **)&address);
+	if (unlikely(length < 0)) {
+		PRINT_ERROR("scst_get_buf_first() failed: %zd", length);
+		scst_set_cmd_error(cmd,
+		    SCST_LOAD_SENSE(scst_sense_hardw_error));
+		goto out;
+	}
+
+	old_fs = get_fs();
+	set_fs(get_ds());
+
+	while (1) {
+		iv_count = 0;
+		full_len = 0;
+		i = -1;
+		while (length > 0) {
+			full_len += length;
+			i++;
+			iv_count++;
+			iv[i].iov_base = address;
+			iv[i].iov_len = length;
+			if (iv_count == UIO_MAXIOV)
+				break;
+			length = scst_get_buf_next(cmd,
+				(uint8_t __force **)&address);
+		}
+		if (length == 0) {
+			finished = true;
+			if (unlikely(iv_count == 0))
+				break;
+		} else if (unlikely(length < 0)) {
+			PRINT_ERROR("scst_get_buf_next() failed: %zd", length);
+			scst_set_cmd_error(cmd,
+			    SCST_LOAD_SENSE(scst_sense_hardw_error));
+			goto out_set_fs;
+		}
+
+		saved_full_len = full_len;
+		eiv = iv;
+		eiv_count = iv_count;
+restart:
+		TRACE_DBG("writing(eiv_count %d, full_len %zd)", eiv_count, full_len);
+
+		/* SEEK */
+		if (fd->f_op->llseek)
+			err = fd->f_op->llseek(fd, loff, 0 /*SEEK_SET */);
+		else
+			err = default_llseek(fd, loff, 0 /*SEEK_SET */);
+		if (err != loff) {
+			PRINT_ERROR("lseek trouble %lld != %lld",
+				    (long long unsigned int)err,
+				    (long long unsigned int)loff);
+			scst_set_cmd_error(cmd,
+				   SCST_LOAD_SENSE(scst_sense_hardw_error));
+			goto out_set_fs;
+		}
+
+		/* WRITE */
+		err = vfs_writev(fd, (struct iovec __force __user *)eiv, eiv_count,
+				 &fd->f_pos);
+
+		if (err < 0) {
+			PRINT_ERROR("write() returned %lld from %zd",
+				    (long long unsigned int)err,
+				    full_len);
+			if (err == -EAGAIN)
+				scst_set_busy(cmd);
+			else {
+				scst_set_cmd_error(cmd,
+				    SCST_LOAD_SENSE(scst_sense_write_error));
+			}
+			goto out_set_fs;
+		} else if (err < full_len) {
+			/*
+			 * Probably that's wrong, but sometimes write() returns
+			 * value less, than requested. Let's restart.
+			 */
+			int e = eiv_count;
+			TRACE_MGMT_DBG("write() returned %d from %zd "
+				"(iv_count=%d)", (int)err, full_len,
+				eiv_count);
+			if (err == 0) {
+				PRINT_INFO("Suspicious: write() returned 0 from "
+					"%zd (iv_count=%d)", full_len, eiv_count);
+			}
+			full_len -= err;
+			for (i = 0; i < e; i++) {
+				if ((long long)eiv->iov_len < err) {
+					err -= eiv->iov_len;
+					eiv++;
+					eiv_count--;
+				} else {
+					eiv->iov_base =
+					    (uint8_t __force __user *)eiv->iov_base + err;
+					eiv->iov_len -= err;
+					break;
+				}
+			}
+			goto restart;
+		}
+
+		for (i = 0; i < iv_count; i++)
+			scst_put_buf(cmd, (void __force *)(iv[i].iov_base));
+
+		if (finished)
+			break;
+
+		loff += saved_full_len;
+		length = scst_get_buf_next(cmd, (uint8_t __force **)&address);
+	}
+
+	set_fs(old_fs);
+
+out:
+	return;
+
+out_set_fs:
+	set_fs(old_fs);
+	for (i = 0; i < iv_count; i++)
+		scst_put_buf(cmd, (void __force *)(iv[i].iov_base));
+	goto out;
+}
+
+struct scst_blockio_work {
+	atomic_t bios_inflight;
+	struct scst_cmd *cmd;
+};
+
+static inline void blockio_check_finish(struct scst_blockio_work *blockio_work)
+{
+	/* Decrement the bios in processing, and if zero signal completion */
+	if (atomic_dec_and_test(&blockio_work->bios_inflight)) {
+		blockio_work->cmd->completed = 1;
+		blockio_work->cmd->scst_cmd_done(blockio_work->cmd,
+			SCST_CMD_STATE_DEFAULT, scst_estimate_context());
+		kmem_cache_free(blockio_work_cachep, blockio_work);
+	}
+	return;
+}
+
+static void blockio_endio(struct bio *bio, int error)
+{
+	struct scst_blockio_work *blockio_work = bio->bi_private;
+
+	if (unlikely(!bio_flagged(bio, BIO_UPTODATE))) {
+		if (error == 0) {
+			PRINT_ERROR("Not up to date bio with error 0 for "
+				"cmd %p, returning -EIO", blockio_work->cmd);
+			error = -EIO;
+		}
+	}
+
+	if (unlikely(error != 0)) {
+		static DEFINE_SPINLOCK(blockio_endio_lock);
+
+		PRINT_ERROR("cmd %p returned error %d", blockio_work->cmd,
+			error);
+
+		/* To protect from several bios finishing simultaneously */
+		spin_lock_bh(&blockio_endio_lock);
+
+		if (bio->bi_rw & (1 << BIO_RW))
+			scst_set_cmd_error(blockio_work->cmd,
+				SCST_LOAD_SENSE(scst_sense_write_error));
+		else
+			scst_set_cmd_error(blockio_work->cmd,
+				SCST_LOAD_SENSE(scst_sense_read_error));
+
+		spin_unlock_bh(&blockio_endio_lock);
+	}
+
+	blockio_check_finish(blockio_work);
+
+	bio_put(bio);
+	return;
+}
+
+static void blockio_exec_rw(struct scst_cmd *cmd, struct scst_vdisk_thr *thr,
+	u64 lba_start, int write)
+{
+	struct scst_vdisk_dev *virt_dev =
+		(struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	struct block_device *bdev = thr->bdev;
+	struct request_queue *q = bdev_get_queue(bdev);
+	int length, max_nr_vecs = 0, offset;
+	struct page *page;
+	struct bio *bio = NULL, *hbio = NULL, *tbio = NULL;
+	int need_new_bio;
+	struct scst_blockio_work *blockio_work;
+	int bios = 0;
+
+	if (virt_dev->nullio)
+		goto out;
+
+	/* Allocate and initialize blockio_work struct */
+	blockio_work = kmem_cache_alloc(blockio_work_cachep, GFP_KERNEL);
+	if (blockio_work == NULL)
+		goto out_no_mem;
+
+	blockio_work->cmd = cmd;
+
+	if (q)
+		max_nr_vecs = min(bio_get_nr_vecs(bdev), BIO_MAX_PAGES);
+	else
+		max_nr_vecs = 1;
+
+	need_new_bio = 1;
+
+	length = scst_get_sg_page_first(cmd, &page, &offset);
+	while (length > 0) {
+		int len, bytes, off, thislen;
+		struct page *pg;
+		u64 lba_start0;
+
+		pg = page;
+		len = length;
+		off = offset;
+		thislen = 0;
+		lba_start0 = lba_start;
+
+		while (len > 0) {
+			int rc;
+
+			if (need_new_bio) {
+				bio = bio_kmalloc(GFP_KERNEL, max_nr_vecs);
+				if (!bio) {
+					PRINT_ERROR("Failed to create bio "
+						"for data segment %d (cmd %p)",
+						cmd->get_sg_buf_entry_num, cmd);
+					goto out_no_bio;
+				}
+
+				bios++;
+				need_new_bio = 0;
+				bio->bi_end_io = blockio_endio;
+				bio->bi_sector = lba_start0 <<
+					(virt_dev->block_shift - 9);
+				bio->bi_bdev = bdev;
+				bio->bi_private = blockio_work;
+				/*
+				 * Better to fail fast w/o any local recovery
+				 * and retries.
+				 */
+#ifdef BIO_RW_FAILFAST
+				bio->bi_rw |= (1 << BIO_RW_FAILFAST);
+#else
+				bio->bi_rw |= (1 << BIO_RW_FAILFAST_DEV) |
+					      (1 << BIO_RW_FAILFAST_TRANSPORT) |
+					      (1 << BIO_RW_FAILFAST_DRIVER);
+#endif
+#if 0 /* It could be win, but could be not, so a performance study is needed */
+				bio->bi_rw |= 1 << BIO_RW_SYNC;
+#endif
+				if (!hbio)
+					hbio = tbio = bio;
+				else
+					tbio = tbio->bi_next = bio;
+			}
+
+			bytes = min_t(unsigned int, len, PAGE_SIZE - off);
+
+			rc = bio_add_page(bio, pg, bytes, off);
+			if (rc < bytes) {
+				BUG_ON(rc != 0);
+				need_new_bio = 1;
+				lba_start0 += thislen >> virt_dev->block_shift;
+				thislen = 0;
+				continue;
+			}
+
+			pg++;
+			thislen += bytes;
+			len -= bytes;
+			off = 0;
+		}
+
+		lba_start += length >> virt_dev->block_shift;
+
+		scst_put_sg_page(cmd, page, offset);
+		length = scst_get_sg_page_next(cmd, &page, &offset);
+	}
+
+	/* +1 to prevent erroneous too early command completion */
+	atomic_set(&blockio_work->bios_inflight, bios+1);
+
+	while (hbio) {
+		bio = hbio;
+		hbio = hbio->bi_next;
+		bio->bi_next = NULL;
+		submit_bio((write != 0), bio);
+	}
+
+	if (q && q->unplug_fn)
+		q->unplug_fn(q);
+
+	blockio_check_finish(blockio_work);
+
+out:
+	return;
+
+out_no_bio:
+	while (hbio) {
+		bio = hbio;
+		hbio = hbio->bi_next;
+		bio_put(bio);
+	}
+	kmem_cache_free(blockio_work_cachep, blockio_work);
+
+out_no_mem:
+	scst_set_busy(cmd);
+	goto out;
+}
+
+static int blockio_flush(struct block_device *bdev)
+{
+	int res = 0;
+
+	res = blkdev_issue_flush(bdev, GFP_KERNEL, NULL, BLKDEV_IFL_WAIT);
+	if (res != 0)
+		PRINT_ERROR("blkdev_issue_flush() failed: %d", res);
+	return res;
+}
+
+static void vdisk_exec_verify(struct scst_cmd *cmd,
+	struct scst_vdisk_thr *thr, loff_t loff)
+{
+	mm_segment_t old_fs;
+	loff_t err;
+	ssize_t length, len_mem = 0;
+	uint8_t *address_sav, *address;
+	int compare;
+	struct scst_vdisk_dev *virt_dev =
+	    (struct scst_vdisk_dev *)cmd->dev->dh_priv;
+	struct file *fd = thr->fd;
+	uint8_t *mem_verify = NULL;
+
+	if (vdisk_fsync(thr, loff, cmd->bufflen, cmd, cmd->dev) != 0)
+		goto out;
+
+	/*
+	 * Until the cache is cleared prior the verifying, there is not
+	 * much point in this code. ToDo.
+	 *
+	 * Nevertherless, this code is valuable if the data have not read
+	 * from the file/disk yet.
+	 */
+
+	/* SEEK */
+	old_fs = get_fs();
+	set_fs(get_ds());
+
+	if (!virt_dev->nullio) {
+		if (fd->f_op->llseek)
+			err = fd->f_op->llseek(fd, loff, 0/*SEEK_SET*/);
+		else
+			err = default_llseek(fd, loff, 0/*SEEK_SET*/);
+		if (err != loff) {
+			PRINT_ERROR("lseek trouble %lld != %lld",
+				    (long long unsigned int)err,
+				    (long long unsigned int)loff);
+			scst_set_cmd_error(cmd,
+				SCST_LOAD_SENSE(scst_sense_hardw_error));
+			goto out_set_fs;
+		}
+	}
+
+	mem_verify = vmalloc(LEN_MEM);
+	if (mem_verify == NULL) {
+		PRINT_ERROR("Unable to allocate memory %d for verify",
+			       LEN_MEM);
+		scst_set_cmd_error(cmd,
+				   SCST_LOAD_SENSE(scst_sense_hardw_error));
+		goto out_set_fs;
+	}
+
+	length = scst_get_buf_first(cmd, &address);
+	address_sav = address;
+	if (!length && cmd->data_len) {
+		length = cmd->data_len;
+		compare = 0;
+	} else
+		compare = 1;
+
+	while (length > 0) {
+		len_mem = (length > LEN_MEM) ? LEN_MEM : length;
+		TRACE_DBG("Verify: length %zd - len_mem %zd", length, len_mem);
+
+		if (!virt_dev->nullio)
+			err = vfs_read(fd, (char __force __user *)mem_verify,
+				len_mem, &fd->f_pos);
+		else
+			err = len_mem;
+		if ((err < 0) || (err < len_mem)) {
+			PRINT_ERROR("verify() returned %lld from %zd",
+				    (long long unsigned int)err, len_mem);
+			if (err == -EAGAIN)
+				scst_set_busy(cmd);
+			else {
+				scst_set_cmd_error(cmd,
+				    SCST_LOAD_SENSE(scst_sense_read_error));
+			}
+			if (compare)
+				scst_put_buf(cmd, address_sav);
+			goto out_set_fs;
+		}
+		if (compare && memcmp(address, mem_verify, len_mem) != 0) {
+			TRACE_DBG("Verify: error memcmp length %zd", length);
+			scst_set_cmd_error(cmd,
+			    SCST_LOAD_SENSE(scst_sense_miscompare_error));
+			scst_put_buf(cmd, address_sav);
+			goto out_set_fs;
+		}
+		length -= len_mem;
+		address += len_mem;
+		if (compare && length <= 0) {
+			scst_put_buf(cmd, address_sav);
+			length = scst_get_buf_next(cmd, &address);
+			address_sav = address;
+		}
+	}
+
+	if (length < 0) {
+		PRINT_ERROR("scst_get_buf_() failed: %zd", length);
+		scst_set_cmd_error(cmd,
+		    SCST_LOAD_SENSE(scst_sense_hardw_error));
+	}
+
+out_set_fs:
+	set_fs(old_fs);
+	if (mem_verify)
+		vfree(mem_verify);
+
+out:
+	return;
+}
+
+static int vdisk_task_mgmt_fn(struct scst_mgmt_cmd *mcmd,
+	struct scst_tgt_dev *tgt_dev)
+{
+
+	if ((mcmd->fn == SCST_LUN_RESET) || (mcmd->fn == SCST_TARGET_RESET)) {
+		/* Restore default values */
+		struct scst_device *dev = tgt_dev->dev;
+		struct scst_vdisk_dev *virt_dev =
+			(struct scst_vdisk_dev *)dev->dh_priv;
+
+		dev->tst = DEF_TST;
+		dev->d_sense = DEF_DSENSE;
+		if (virt_dev->wt_flag && !virt_dev->nv_cache)
+			dev->queue_alg = DEF_QUEUE_ALG_WT;
+		else
+			dev->queue_alg = DEF_QUEUE_ALG;
+		dev->swp = DEF_SWP;
+		dev->tas = DEF_TAS;
+
+		spin_lock(&virt_dev->flags_lock);
+		virt_dev->prevent_allow_medium_removal = 0;
+		spin_unlock(&virt_dev->flags_lock);
+	} else if (mcmd->fn == SCST_PR_ABORT_ALL) {
+		struct scst_device *dev = tgt_dev->dev;
+		struct scst_vdisk_dev *virt_dev =
+			(struct scst_vdisk_dev *)dev->dh_priv;
+		spin_lock(&virt_dev->flags_lock);
+		virt_dev->prevent_allow_medium_removal = 0;
+		spin_unlock(&virt_dev->flags_lock);
+	}
+	return SCST_DEV_TM_NOT_COMPLETED;
+}
+
+static void vdisk_report_registering(const struct scst_vdisk_dev *virt_dev)
+{
+	char buf[128];
+	int i, j;
+
+	i = snprintf(buf, sizeof(buf), "Registering virtual %s device %s ",
+		virt_dev->vdev_devt->name, virt_dev->name);
+	j = i;
+
+	if (virt_dev->wt_flag)
+		i += snprintf(&buf[i], sizeof(buf) - i, "(WRITE_THROUGH");
+
+	if (virt_dev->nv_cache)
+		i += snprintf(&buf[i], sizeof(buf) - i, "%sNV_CACHE",
+			(j == i) ? "(" : ", ");
+
+	if (virt_dev->rd_only)
+		i += snprintf(&buf[i], sizeof(buf) - i, "%sREAD_ONLY",
+			(j == i) ? "(" : ", ");
+
+	if (virt_dev->o_direct_flag)
+		i += snprintf(&buf[i], sizeof(buf) - i, "%sO_DIRECT",
+			(j == i) ? "(" : ", ");
+
+	if (virt_dev->nullio)
+		i += snprintf(&buf[i], sizeof(buf) - i, "%sNULLIO",
+			(j == i) ? "(" : ", ");
+
+	if (virt_dev->blockio)
+		i += snprintf(&buf[i], sizeof(buf) - i, "%sBLOCKIO",
+			(j == i) ? "(" : ", ");
+
+	if (virt_dev->removable)
+		i += snprintf(&buf[i], sizeof(buf) - i, "%sREMOVABLE",
+			(j == i) ? "(" : ", ");
+
+	if (virt_dev->thin_provisioned)
+		i += snprintf(&buf[i], sizeof(buf) - i, "%sTHIN PROVISIONED",
+			(j == i) ? "(" : ", ");
+
+	if (j == i)
+		PRINT_INFO("%s", buf);
+	else
+		PRINT_INFO("%s)", buf);
+
+	return;
+}
+
+static int vdisk_resync_size(struct scst_vdisk_dev *virt_dev)
+{
+	loff_t file_size;
+	int res = 0;
+
+	BUG_ON(virt_dev->nullio);
+
+	res = vdisk_get_file_size(virt_dev->filename,
+			virt_dev->blockio, &file_size);
+	if (res != 0)
+		goto out;
+
+	if (file_size == virt_dev->file_size) {
+		PRINT_INFO("Size of virtual disk %s remained the same",
+			virt_dev->name);
+		goto out;
+	}
+
+	res = scst_suspend_activity(true);
+	if (res != 0)
+		goto out;
+
+	virt_dev->file_size = file_size;
+	virt_dev->nblocks = virt_dev->file_size >> virt_dev->block_shift;
+
+	scst_dev_del_all_thr_data(virt_dev->dev);
+
+	PRINT_INFO("New size of SCSI target virtual disk %s "
+		"(fs=%lldMB, bs=%d, nblocks=%lld, cyln=%lld%s)",
+		virt_dev->name, virt_dev->file_size >> 20,
+		virt_dev->block_size,
+		(long long unsigned int)virt_dev->nblocks,
+		(long long unsigned int)virt_dev->nblocks/64/32,
+		virt_dev->nblocks < 64*32 ? " !WARNING! cyln less "
+						"than 1" : "");
+
+	scst_capacity_data_changed(virt_dev->dev);
+
+	scst_resume_activity();
+
+out:
+	return res;
+}
+
+static int vdev_create(struct scst_dev_type *devt,
+	const char *name, struct scst_vdisk_dev **res_virt_dev)
+{
+	int res = 0;
+	struct scst_vdisk_dev *virt_dev;
+	uint64_t dev_id_num;
+	int dev_id_len;
+	char dev_id_str[17];
+	int32_t i;
+
+	virt_dev = kzalloc(sizeof(*virt_dev), GFP_KERNEL);
+	if (virt_dev == NULL) {
+		PRINT_ERROR("Allocation of virtual device %s failed",
+			devt->name);
+		res = -ENOMEM;
+		goto out;
+	}
+
+	spin_lock_init(&virt_dev->flags_lock);
+	virt_dev->vdev_devt = devt;
+
+	virt_dev->rd_only = DEF_RD_ONLY;
+	virt_dev->removable = DEF_REMOVABLE;
+	virt_dev->thin_provisioned = DEF_THIN_PROVISIONED;
+
+	virt_dev->block_size = DEF_DISK_BLOCKSIZE;
+	virt_dev->block_shift = DEF_DISK_BLOCKSIZE_SHIFT;
+
+	if (strlen(name) >= sizeof(virt_dev->name)) {
+		PRINT_ERROR("Name %s is too long (max allowed %zd)", name,
+			sizeof(virt_dev->name)-1);
+		res = -EINVAL;
+		goto out_free;
+	}
+	strcpy(virt_dev->name, name);
+
+	dev_id_num = vdisk_gen_dev_id_num(virt_dev->name);
+	dev_id_len = scnprintf(dev_id_str, sizeof(dev_id_str), "%llx",
+				dev_id_num);
+
+	i = strlen(virt_dev->name) + 1; /* for ' ' */
+	memset(virt_dev->t10_dev_id, ' ', i + dev_id_len);
+	memcpy(virt_dev->t10_dev_id, virt_dev->name, i-1);
+	memcpy(virt_dev->t10_dev_id + i, dev_id_str, dev_id_len);
+	TRACE_DBG("t10_dev_id %s", virt_dev->t10_dev_id);
+
+	scnprintf(virt_dev->usn, sizeof(virt_dev->usn), "%llx", dev_id_num);
+	TRACE_DBG("usn %s", virt_dev->usn);
+
+	*res_virt_dev = virt_dev;
+
+out:
+	return res;
+
+out_free:
+	kfree(virt_dev);
+	goto out;
+}
+
+static void vdev_destroy(struct scst_vdisk_dev *virt_dev)
+{
+	kfree(virt_dev->filename);
+	kfree(virt_dev);
+	return;
+}
+
+/* scst_vdisk_mutex supposed to be held */
+static struct scst_vdisk_dev *vdev_find(const char *name)
+{
+	struct scst_vdisk_dev *res, *vv;
+
+	res = NULL;
+	list_for_each_entry(vv, &vdev_list, vdev_list_entry) {
+		if (strcmp(vv->name, name) == 0) {
+			res = vv;
+			break;
+		}
+	}
+	return res;
+}
+
+static int vdev_parse_add_dev_params(struct scst_vdisk_dev *virt_dev,
+	char *params, const char *allowed_params[])
+{
+	int res = 0;
+	unsigned long val;
+	char *param, *p, *pp;
+
+	while (1) {
+		param = scst_get_next_token_str(&params);
+		if (param == NULL)
+			break;
+
+		p = scst_get_next_lexem(&param);
+		if (*p == '\0') {
+			PRINT_ERROR("Syntax error at %s (device %s)",
+				param, virt_dev->name);
+			res = -EINVAL;
+			goto out;
+		}
+
+		if (allowed_params != NULL) {
+			const char **a = allowed_params;
+			bool allowed = false;
+
+			while (*a != NULL) {
+				if (!strcasecmp(*a, p)) {
+					allowed = true;
+					break;
+				}
+				a++;
+			}
+
+			if (!allowed) {
+				PRINT_ERROR("Unknown parameter %s (device %s)", p,
+					virt_dev->name);
+				res = -EINVAL;
+				goto out;
+			}
+		}
+
+		pp = scst_get_next_lexem(&param);
+		if (*pp == '\0') {
+			PRINT_ERROR("Parameter %s value missed for device %s",
+				p, virt_dev->name);
+			res = -EINVAL;
+			goto out;
+		}
+
+		if (scst_get_next_lexem(&param)[0] != '\0') {
+			PRINT_ERROR("Too many parameter's %s values (device %s)",
+				p, virt_dev->name);
+			res = -EINVAL;
+			goto out;
+		}
+
+		if (!strcasecmp("filename", p)) {
+			if (*pp != '/') {
+				PRINT_ERROR("Filename %s must be global "
+					"(device %s)", pp, virt_dev->name);
+				res = -EINVAL;
+				goto out;
+			}
+
+			virt_dev->filename = kstrdup(pp, GFP_KERNEL);
+			if (virt_dev->filename == NULL) {
+				PRINT_ERROR("Unable to duplicate file name %s "
+					"(device %s)", pp, virt_dev->name);
+				res = -ENOMEM;
+				goto out;
+			}
+			continue;
+		}
+
+		res = strict_strtoul(pp, 0, &val);
+		if (res != 0) {
+			PRINT_ERROR("strict_strtoul() for %s failed: %d "
+				"(device %s)", pp, res, virt_dev->name);
+			goto out;
+		}
+
+		if (!strcasecmp("write_through", p)) {
+			virt_dev->wt_flag = val;
+			TRACE_DBG("WRITE THROUGH %d", virt_dev->wt_flag);
+		} else if (!strcasecmp("nv_cache", p)) {
+			virt_dev->nv_cache = val;
+			TRACE_DBG("NON-VOLATILE CACHE %d", virt_dev->nv_cache);
+		} else if (!strcasecmp("o_direct", p)) {
+#if 0
+			virt_dev->o_direct_flag = val;
+			TRACE_DBG("O_DIRECT %d", virt_dev->o_direct_flag);
+#else
+			PRINT_INFO("O_DIRECT flag doesn't currently"
+				" work, ignoring it, use fileio_tgt "
+				"in O_DIRECT mode instead (device %s)", virt_dev->name);
+#endif
+		} else if (!strcasecmp("read_only", p)) {
+			virt_dev->rd_only = val;
+			TRACE_DBG("READ ONLY %d", virt_dev->rd_only);
+		} else if (!strcasecmp("removable", p)) {
+			virt_dev->removable = val;
+			TRACE_DBG("REMOVABLE %d", virt_dev->removable);
+		} else if (!strcasecmp("thin_provisioned", p)) {
+			virt_dev->thin_provisioned = val;
+			TRACE_DBG("THIN PROVISIONED %d",
+				virt_dev->thin_provisioned);
+		} else if (!strcasecmp("blocksize", p)) {
+			virt_dev->block_size = val;
+			virt_dev->block_shift = scst_calc_block_shift(
+							virt_dev->block_size);
+			if (virt_dev->block_shift < 9) {
+				res = -EINVAL;
+				goto out;
+			}
+			TRACE_DBG("block_size %d, block_shift %d",
+				virt_dev->block_size,
+				virt_dev->block_shift);
+		} else {
+			PRINT_ERROR("Unknown parameter %s (device %s)", p,
+				virt_dev->name);
+			res = -EINVAL;
+			goto out;
+		}
+	}
+
+out:
+	return res;
+}
+
+/* scst_vdisk_mutex supposed to be held */
+static int vdev_fileio_add_device(const char *device_name, char *params)
+{
+	int res = 0;
+	struct scst_vdisk_dev *virt_dev;
+
+	res = vdev_create(&vdisk_file_devtype, device_name, &virt_dev);
+	if (res != 0)
+		goto out;
+
+	virt_dev->command_set_version = 0x04C0; /* SBC-3 */
+
+	virt_dev->wt_flag = DEF_WRITE_THROUGH;
+	virt_dev->nv_cache = DEF_NV_CACHE;
+	virt_dev->o_direct_flag = DEF_O_DIRECT;
+
+	res = vdev_parse_add_dev_params(virt_dev, params, NULL);
+	if (res != 0)
+		goto out_destroy;
+
+	if (virt_dev->rd_only && (virt_dev->wt_flag || virt_dev->nv_cache)) {
+		PRINT_ERROR("Write options on read only device %s",
+			virt_dev->name);
+		res = -EINVAL;
+		goto out_destroy;
+	}
+
+	if (virt_dev->filename == NULL) {
+		PRINT_ERROR("File name required (device %s)", virt_dev->name);
+		res = -EINVAL;
+		goto out_destroy;
+	}
+
+	list_add_tail(&virt_dev->vdev_list_entry, &vdev_list);
+
+	vdisk_report_registering(virt_dev);
+
+	virt_dev->virt_id = scst_register_virtual_device(virt_dev->vdev_devt,
+					virt_dev->name);
+	if (virt_dev->virt_id < 0) {
+		res = virt_dev->virt_id;
+		goto out_del;
+	}
+
+	TRACE_DBG("Registered virt_dev %s with id %d", virt_dev->name,
+		virt_dev->virt_id);
+
+out:
+	return res;
+
+out_del:
+	list_del(&virt_dev->vdev_list_entry);
+
+out_destroy:
+	vdev_destroy(virt_dev);
+	goto out;
+}
+
+/* scst_vdisk_mutex supposed to be held */
+static int vdev_blockio_add_device(const char *device_name, char *params)
+{
+	int res = 0;
+	const char *allowed_params[] = { "filename", "read_only", "removable",
+					 "blocksize", "nv_cache",
+					 "thin_provisioned", NULL };
+	struct scst_vdisk_dev *virt_dev;
+
+	res = vdev_create(&vdisk_blk_devtype, device_name, &virt_dev);
+	if (res != 0)
+		goto out;
+
+	virt_dev->command_set_version = 0x04C0; /* SBC-3 */
+
+	virt_dev->blockio = 1;
+
+	res = vdev_parse_add_dev_params(virt_dev, params, allowed_params);
+	if (res != 0)
+		goto out_destroy;
+
+	if (virt_dev->filename == NULL) {
+		PRINT_ERROR("File name required (device %s)", virt_dev->name);
+		res = -EINVAL;
+		goto out_destroy;
+	}
+
+	list_add_tail(&virt_dev->vdev_list_entry, &vdev_list);
+
+	vdisk_report_registering(virt_dev);
+
+	virt_dev->virt_id = scst_register_virtual_device(virt_dev->vdev_devt,
+					virt_dev->name);
+	if (virt_dev->virt_id < 0) {
+		res = virt_dev->virt_id;
+		goto out_del;
+	}
+
+	TRACE_DBG("Registered virt_dev %s with id %d", virt_dev->name,
+		virt_dev->virt_id);
+
+out:
+	return res;
+
+out_del:
+	list_del(&virt_dev->vdev_list_entry);
+
+out_destroy:
+	vdev_destroy(virt_dev);
+	goto out;
+}
+
+/* scst_vdisk_mutex supposed to be held */
+static int vdev_nullio_add_device(const char *device_name, char *params)
+{
+	int res = 0;
+	const char *allowed_params[] = { "read_only", "removable",
+					 "blocksize", NULL };
+	struct scst_vdisk_dev *virt_dev;
+
+	res = vdev_create(&vdisk_null_devtype, device_name, &virt_dev);
+	if (res != 0)
+		goto out;
+
+	virt_dev->command_set_version = 0x04C0; /* SBC-3 */
+
+	virt_dev->nullio = 1;
+
+	res = vdev_parse_add_dev_params(virt_dev, params, allowed_params);
+	if (res != 0)
+		goto out_destroy;
+
+	list_add_tail(&virt_dev->vdev_list_entry, &vdev_list);
+
+	vdisk_report_registering(virt_dev);
+
+	virt_dev->virt_id = scst_register_virtual_device(virt_dev->vdev_devt,
+					virt_dev->name);
+	if (virt_dev->virt_id < 0) {
+		res = virt_dev->virt_id;
+		goto out_del;
+	}
+
+	TRACE_DBG("Registered virt_dev %s with id %d", virt_dev->name,
+		virt_dev->virt_id);
+
+out:
+	return res;
+
+out_del:
+	list_del(&virt_dev->vdev_list_entry);
+
+out_destroy:
+	vdev_destroy(virt_dev);
+	goto out;
+}
+
+static ssize_t vdisk_add_fileio_device(const char *device_name, char *params)
+{
+	int res;
+
+	if (mutex_lock_interruptible(&scst_vdisk_mutex) != 0) {
+		res = -EINTR;
+		goto out;
+	}
+
+	res = vdev_fileio_add_device(device_name, params);
+
+	mutex_unlock(&scst_vdisk_mutex);
+
+out:
+	return res;
+}
+
+static ssize_t vdisk_add_blockio_device(const char *device_name, char *params)
+{
+	int res;
+
+	if (mutex_lock_interruptible(&scst_vdisk_mutex) != 0) {
+		res = -EINTR;
+		goto out;
+	}
+
+	res = vdev_blockio_add_device(device_name, params);
+
+	mutex_unlock(&scst_vdisk_mutex);
+
+out:
+	return res;
+
+}
+
+static ssize_t vdisk_add_nullio_device(const char *device_name, char *params)
+{
+	int res;
+
+	if (mutex_lock_interruptible(&scst_vdisk_mutex) != 0) {
+		res = -EINTR;
+		goto out;
+	}
+
+	res = vdev_nullio_add_device(device_name, params);
+
+	mutex_unlock(&scst_vdisk_mutex);
+
+out:
+	return res;
+
+}
+
+/* scst_vdisk_mutex supposed to be held */
+static void vdev_del_device(struct scst_vdisk_dev *virt_dev)
+{
+
+	scst_unregister_virtual_device(virt_dev->virt_id);
+
+	list_del(&virt_dev->vdev_list_entry);
+
+	PRINT_INFO("Virtual device %s unregistered", virt_dev->name);
+	TRACE_DBG("virt_id %d unregistered", virt_dev->virt_id);
+
+	vdev_destroy(virt_dev);
+
+	return;
+}
+
+static ssize_t vdisk_del_device(const char *device_name)
+{
+	int res = 0;
+	struct scst_vdisk_dev *virt_dev;
+
+	if (mutex_lock_interruptible(&scst_vdisk_mutex) != 0) {
+		res = -EINTR;
+		goto out;
+	}
+
+	virt_dev = vdev_find(device_name);
+	if (virt_dev == NULL) {
+		PRINT_ERROR("Device %s not found", device_name);
+		res = -EINVAL;
+		goto out_unlock;
+	}
+
+	vdev_del_device(virt_dev);
+
+out_unlock:
+	mutex_unlock(&scst_vdisk_mutex);
+
+out:
+	return res;
+}
+
+/* scst_vdisk_mutex supposed to be held */
+static ssize_t __vcdrom_add_device(const char *device_name, char *params)
+{
+	int res = 0;
+	const char *allowed_params[] = { NULL }; /* no params */
+	struct scst_vdisk_dev *virt_dev;
+
+	res = vdev_create(&vcdrom_devtype, device_name, &virt_dev);
+	if (res != 0)
+		goto out;
+
+	virt_dev->command_set_version = 0x02A0; /* MMC-3 */
+
+	virt_dev->rd_only = 1;
+	virt_dev->removable = 1;
+	virt_dev->cdrom_empty = 1;
+
+	virt_dev->block_size = DEF_CDROM_BLOCKSIZE;
+	virt_dev->block_shift = DEF_CDROM_BLOCKSIZE_SHIFT;
+
+	res = vdev_parse_add_dev_params(virt_dev, params, allowed_params);
+	if (res != 0)
+		goto out_destroy;
+
+	list_add_tail(&virt_dev->vdev_list_entry, &vdev_list);
+
+	vdisk_report_registering(virt_dev);
+
+	virt_dev->virt_id = scst_register_virtual_device(virt_dev->vdev_devt,
+					virt_dev->name);
+	if (virt_dev->virt_id < 0) {
+		res = virt_dev->virt_id;
+		goto out_del;
+	}
+
+	TRACE_DBG("Registered virt_dev %s with id %d", virt_dev->name,
+		virt_dev->virt_id);
+
+out:
+	return res;
+
+out_del:
+	list_del(&virt_dev->vdev_list_entry);
+
+out_destroy:
+	vdev_destroy(virt_dev);
+	goto out;
+}
+
+static ssize_t vcdrom_add_device(const char *device_name, char *params)
+{
+	int res;
+
+	if (mutex_lock_interruptible(&scst_vdisk_mutex) != 0) {
+		res = -EINTR;
+		goto out;
+	}
+
+	res = __vcdrom_add_device(device_name, params);
+
+	mutex_unlock(&scst_vdisk_mutex);
+
+out:
+	return res;
+
+}
+
+static ssize_t vcdrom_del_device(const char *device_name)
+{
+	int res = 0;
+	struct scst_vdisk_dev *virt_dev;
+
+	if (mutex_lock_interruptible(&scst_vdisk_mutex) != 0) {
+		res = -EINTR;
+		goto out;
+	}
+
+	virt_dev = vdev_find(device_name);
+	if (virt_dev == NULL) {
+		PRINT_ERROR("Device %s not found", device_name);
+		res = -EINVAL;
+		goto out_unlock;
+	}
+
+	vdev_del_device(virt_dev);
+
+out_unlock:
+	mutex_unlock(&scst_vdisk_mutex);
+
+out:
+	return res;
+}
+
+static int vcdrom_change(struct scst_vdisk_dev *virt_dev,
+	char *buffer)
+{
+	loff_t err;
+	char *old_fn, *p, *pp;
+	const char *filename = NULL;
+	int length = strlen(buffer);
+	int res = 0;
+
+	p = buffer;
+
+	while (isspace(*p) && *p != '\0')
+		p++;
+	filename = p;
+	p = &buffer[length-1];
+	pp = &buffer[length];
+	while (isspace(*p) && (*p != '\0')) {
+		pp = p;
+		p--;
+	}
+	*pp = '\0';
+
+	res = scst_suspend_activity(true);
+	if (res != 0)
+		goto out;
+
+	/* To sync with detach*() functions */
+	mutex_lock(&scst_mutex);
+
+	if (*filename == '\0') {
+		virt_dev->cdrom_empty = 1;
+		TRACE_DBG("%s", "No media");
+	} else if (*filename != '/') {
+		PRINT_ERROR("File path \"%s\" is not absolute", filename);
+		res = -EINVAL;
+		goto out_unlock;
+	} else
+		virt_dev->cdrom_empty = 0;
+
+	old_fn = virt_dev->filename;
+
+	if (!virt_dev->cdrom_empty) {
+		int len = strlen(filename) + 1;
+		char *fn = kmalloc(len, GFP_KERNEL);
+		if (fn == NULL) {
+			TRACE(TRACE_OUT_OF_MEM, "%s",
+				"Allocation of filename failed");
+			res = -ENOMEM;
+			goto out_unlock;
+		}
+
+		strlcpy(fn, filename, len);
+		virt_dev->filename = fn;
+
+		res = vdisk_get_file_size(virt_dev->filename,
+				virt_dev->blockio, &err);
+		if (res != 0)
+			goto out_free_fn;
+	} else {
+		err = 0;
+		virt_dev->filename = NULL;
+	}
+
+	if (virt_dev->prevent_allow_medium_removal) {
+		PRINT_ERROR("Prevent medium removal for "
+			"virtual device with name %s", virt_dev->name);
+		res = -EINVAL;
+		goto out_free_fn;
+	}
+
+	virt_dev->file_size = err;
+	virt_dev->nblocks = virt_dev->file_size >> virt_dev->block_shift;
+	if (!virt_dev->cdrom_empty)
+		virt_dev->media_changed = 1;
+
+	mutex_unlock(&scst_mutex);
+
+	scst_dev_del_all_thr_data(virt_dev->dev);
+
+	if (!virt_dev->cdrom_empty) {
+		PRINT_INFO("Changed SCSI target virtual cdrom %s "
+			"(file=\"%s\", fs=%lldMB, bs=%d, nblocks=%lld,"
+			" cyln=%lld%s)", virt_dev->name,
+			vdev_get_filename(virt_dev),
+			virt_dev->file_size >> 20, virt_dev->block_size,
+			(long long unsigned int)virt_dev->nblocks,
+			(long long unsigned int)virt_dev->nblocks/64/32,
+			virt_dev->nblocks < 64*32 ? " !WARNING! cyln less "
+							"than 1" : "");
+	} else {
+		PRINT_INFO("Removed media from SCSI target virtual cdrom %s",
+			virt_dev->name);
+	}
+
+	kfree(old_fn);
+
+out_resume:
+	scst_resume_activity();
+
+out:
+	return res;
+
+out_free_fn:
+	kfree(virt_dev->filename);
+	virt_dev->filename = old_fn;
+
+out_unlock:
+	mutex_unlock(&scst_mutex);
+	goto out_resume;
+}
+
+static int vcdrom_sysfs_process_filename_store(struct scst_sysfs_work_item *work)
+{
+	int res;
+	struct scst_device *dev = work->dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	/* It's safe, since we taken dev_kobj and dh_priv NULLed in attach() */
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	res = vcdrom_change(virt_dev, work->buf);
+
+	kobject_put(&dev->dev_kobj);
+	return res;
+}
+
+static ssize_t vcdrom_sysfs_filename_store(struct kobject *kobj,
+	struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	int res;
+	char *i_buf;
+	struct scst_sysfs_work_item *work;
+	struct scst_device *dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+
+	i_buf = kmalloc(count+1, GFP_KERNEL);
+	if (i_buf == NULL) {
+		PRINT_ERROR("Unable to alloc intermediate buffer with size %zd",
+			count+1);
+		res = -ENOMEM;
+		goto out;
+	}
+	memcpy(i_buf, buf, count);
+	i_buf[count] = '\0';
+
+	res = scst_alloc_sysfs_work(vcdrom_sysfs_process_filename_store,
+					false, &work);
+	if (res != 0)
+		goto out_free;
+
+	work->buf = i_buf;
+	work->dev = dev;
+
+	kobject_get(&dev->dev_kobj);
+
+	res = scst_sysfs_queue_wait_work(work);
+	if (res == 0)
+		res = count;
+
+out:
+	return res;
+
+out_free:
+	kfree(i_buf);
+	goto out;
+}
+
+static ssize_t vdev_sysfs_size_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int pos = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	pos = sprintf(buf, "%lld\n", virt_dev->file_size / 1024 / 1024);
+	return pos;
+}
+
+static ssize_t vdisk_sysfs_blocksize_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int pos = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	pos = sprintf(buf, "%d\n%s", (int)virt_dev->block_size,
+		(virt_dev->block_size == DEF_DISK_BLOCKSIZE) ? "" :
+			SCST_SYSFS_KEY_MARK "\n");
+	return pos;
+}
+
+static ssize_t vdisk_sysfs_rd_only_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int pos = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	pos = sprintf(buf, "%d\n%s", virt_dev->rd_only ? 1 : 0,
+		(virt_dev->rd_only == DEF_RD_ONLY) ? "" :
+			SCST_SYSFS_KEY_MARK "");
+	return pos;
+}
+
+static ssize_t vdisk_sysfs_wt_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int pos = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	pos = sprintf(buf, "%d\n%s", virt_dev->wt_flag ? 1 : 0,
+		(virt_dev->wt_flag == DEF_WRITE_THROUGH) ? "" :
+			SCST_SYSFS_KEY_MARK "");
+	return pos;
+}
+
+static ssize_t vdisk_sysfs_tp_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int pos = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	pos = sprintf(buf, "%d\n%s", virt_dev->thin_provisioned ? 1 : 0,
+		(virt_dev->thin_provisioned == DEF_THIN_PROVISIONED) ? "" :
+			SCST_SYSFS_KEY_MARK "");
+	return pos;
+}
+
+static ssize_t vdisk_sysfs_nv_cache_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int pos = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	pos = sprintf(buf, "%d\n%s", virt_dev->nv_cache ? 1 : 0,
+		(virt_dev->nv_cache == DEF_NV_CACHE) ? "" :
+			SCST_SYSFS_KEY_MARK "");
+	return pos;
+}
+
+static ssize_t vdisk_sysfs_o_direct_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int pos = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	pos = sprintf(buf, "%d\n%s", virt_dev->o_direct_flag ? 1 : 0,
+		(virt_dev->o_direct_flag == DEF_O_DIRECT) ? "" :
+			SCST_SYSFS_KEY_MARK "");
+	return pos;
+}
+
+static ssize_t vdisk_sysfs_removable_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int pos = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	pos = sprintf(buf, "%d\n", virt_dev->removable ? 1 : 0);
+
+	if ((virt_dev->dev->type != TYPE_ROM) &&
+	    (virt_dev->removable != DEF_REMOVABLE))
+		pos += sprintf(&buf[pos], "%s\n", SCST_SYSFS_KEY_MARK);
+	return pos;
+}
+
+static int vdev_sysfs_process_get_filename(struct scst_sysfs_work_item *work)
+{
+	int res = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = work->dev;
+
+	if (mutex_lock_interruptible(&scst_vdisk_mutex) != 0) {
+		res = -EINTR;
+		goto out_put;
+	}
+
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	if (virt_dev == NULL)
+		goto out_unlock;
+
+	if (virt_dev->filename != NULL)
+		work->res_buf = kasprintf(GFP_KERNEL, "%s\n%s\n",
+			vdev_get_filename(virt_dev), SCST_SYSFS_KEY_MARK);
+	else
+		work->res_buf = kasprintf(GFP_KERNEL, "%s\n",
+					vdev_get_filename(virt_dev));
+
+out_unlock:
+	mutex_unlock(&scst_vdisk_mutex);
+
+out_put:
+	kobject_put(&dev->dev_kobj);
+	return res;
+}
+
+static ssize_t vdev_sysfs_filename_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int res = 0;
+	struct scst_device *dev;
+	struct scst_sysfs_work_item *work;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+
+	res = scst_alloc_sysfs_work(vdev_sysfs_process_get_filename,
+					true, &work);
+	if (res != 0)
+		goto out;
+
+	work->dev = dev;
+
+	kobject_get(&dev->dev_kobj);
+
+	scst_sysfs_work_get(work);
+
+	res = scst_sysfs_queue_wait_work(work);
+	if (res != 0)
+		goto out_put;
+
+	res = snprintf(buf, SCST_SYSFS_BLOCK_SIZE, "%s\n", work->res_buf);
+
+out_put:
+	scst_sysfs_work_put(work);
+
+out:
+	return res;
+}
+
+static int vdisk_sysfs_process_resync_size_store(
+	struct scst_sysfs_work_item *work)
+{
+	int res;
+	struct scst_device *dev = work->dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	/* It's safe, since we taken dev_kobj and dh_priv NULLed in attach() */
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	res = vdisk_resync_size(virt_dev);
+
+	kobject_put(&dev->dev_kobj);
+	return res;
+}
+
+static ssize_t vdisk_sysfs_resync_size_store(struct kobject *kobj,
+	struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	int res;
+	struct scst_device *dev;
+	struct scst_sysfs_work_item *work;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+
+	res = scst_alloc_sysfs_work(vdisk_sysfs_process_resync_size_store,
+					false, &work);
+	if (res != 0)
+		goto out;
+
+	work->dev = dev;
+
+	kobject_get(&dev->dev_kobj);
+
+	res = scst_sysfs_queue_wait_work(work);
+	if (res == 0)
+		res = count;
+
+out:
+	return res;
+}
+
+static ssize_t vdev_sysfs_t10_dev_id_store(struct kobject *kobj,
+	struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	int res, i;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	write_lock_bh(&vdisk_t10_dev_id_rwlock);
+
+	if ((count > sizeof(virt_dev->t10_dev_id)) ||
+	    ((count == sizeof(virt_dev->t10_dev_id)) &&
+	     (buf[count-1] != '\n'))) {
+		PRINT_ERROR("T10 device id is too long (max %zd "
+			"characters)", sizeof(virt_dev->t10_dev_id)-1);
+		res = -EINVAL;
+		goto out_unlock;
+	}
+
+	memset(virt_dev->t10_dev_id, 0, sizeof(virt_dev->t10_dev_id));
+	memcpy(virt_dev->t10_dev_id, buf, count);
+
+	i = 0;
+	while (i < sizeof(virt_dev->t10_dev_id)) {
+		if (virt_dev->t10_dev_id[i] == '\n') {
+			virt_dev->t10_dev_id[i] = '\0';
+			break;
+		}
+		i++;
+	}
+
+	virt_dev->t10_dev_id_set = 1;
+
+	res = count;
+
+	PRINT_INFO("T10 device id for device %s changed to %s", virt_dev->name,
+		virt_dev->t10_dev_id);
+
+out_unlock:
+	write_unlock_bh(&vdisk_t10_dev_id_rwlock);
+	return res;
+}
+
+static ssize_t vdev_sysfs_t10_dev_id_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int pos = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	read_lock_bh(&vdisk_t10_dev_id_rwlock);
+	pos = sprintf(buf, "%s\n%s", virt_dev->t10_dev_id,
+		virt_dev->t10_dev_id_set ? SCST_SYSFS_KEY_MARK "\n" : "");
+	read_unlock_bh(&vdisk_t10_dev_id_rwlock);
+	return pos;
+}
+
+static ssize_t vdev_sysfs_usn_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	int pos = 0;
+	struct scst_device *dev;
+	struct scst_vdisk_dev *virt_dev;
+
+	dev = container_of(kobj, struct scst_device, dev_kobj);
+	virt_dev = (struct scst_vdisk_dev *)dev->dh_priv;
+
+	pos = sprintf(buf, "%s\n", virt_dev->usn);
+	return pos;
+}
+
+static int __init init_scst_vdisk(struct scst_dev_type *devtype)
+{
+	int res = 0;
+
+	devtype->module = THIS_MODULE;
+
+	res = scst_register_virtual_dev_driver(devtype);
+	if (res < 0)
+		goto out;
+
+out:
+	return res;
+
+}
+
+static void exit_scst_vdisk(struct scst_dev_type *devtype)
+{
+
+	mutex_lock(&scst_vdisk_mutex);
+	while (1) {
+		struct scst_vdisk_dev *virt_dev;
+
+		if (list_empty(&vdev_list))
+			break;
+
+		virt_dev = list_entry(vdev_list.next, typeof(*virt_dev),
+				vdev_list_entry);
+
+		vdev_del_device(virt_dev);
+	}
+	mutex_unlock(&scst_vdisk_mutex);
+
+	scst_unregister_virtual_dev_driver(devtype);
+	return;
+}
+
+static int __init init_scst_vdisk_driver(void)
+{
+	int res;
+
+	vdisk_thr_cachep = KMEM_CACHE(scst_vdisk_thr, SCST_SLAB_FLAGS);
+	if (vdisk_thr_cachep == NULL) {
+		res = -ENOMEM;
+		goto out;
+	}
+
+	blockio_work_cachep = KMEM_CACHE(scst_blockio_work, SCST_SLAB_FLAGS);
+	if (blockio_work_cachep == NULL) {
+		res = -ENOMEM;
+		goto out_free_vdisk_cache;
+	}
+
+	if (num_threads < 1) {
+		PRINT_ERROR("num_threads can not be less than 1, use "
+			"default %d", DEF_NUM_THREADS);
+		num_threads = DEF_NUM_THREADS;
+	}
+
+	vdisk_file_devtype.threads_num = num_threads;
+	vcdrom_devtype.threads_num = num_threads;
+
+	atomic_set(&nullio_thr_data.hdr.ref, 1); /* never destroy it */
+
+	res = init_scst_vdisk(&vdisk_file_devtype);
+	if (res != 0)
+		goto out_free_slab;
+
+	res = init_scst_vdisk(&vdisk_blk_devtype);
+	if (res != 0)
+		goto out_free_vdisk;
+
+	res = init_scst_vdisk(&vdisk_null_devtype);
+	if (res != 0)
+		goto out_free_blk;
+
+	res = init_scst_vdisk(&vcdrom_devtype);
+	if (res != 0)
+		goto out_free_null;
+
+out:
+	return res;
+
+out_free_null:
+	exit_scst_vdisk(&vdisk_null_devtype);
+
+out_free_blk:
+	exit_scst_vdisk(&vdisk_blk_devtype);
+
+out_free_vdisk:
+	exit_scst_vdisk(&vdisk_file_devtype);
+
+out_free_slab:
+	kmem_cache_destroy(blockio_work_cachep);
+
+out_free_vdisk_cache:
+	kmem_cache_destroy(vdisk_thr_cachep);
+	goto out;
+}
+
+static void __exit exit_scst_vdisk_driver(void)
+{
+	exit_scst_vdisk(&vdisk_null_devtype);
+	exit_scst_vdisk(&vdisk_blk_devtype);
+	exit_scst_vdisk(&vdisk_file_devtype);
+	exit_scst_vdisk(&vcdrom_devtype);
+
+	kmem_cache_destroy(blockio_work_cachep);
+	kmem_cache_destroy(vdisk_thr_cachep);
+}
+
+module_init(init_scst_vdisk_driver);
+module_exit(exit_scst_vdisk_driver);
+
+MODULE_AUTHOR("Vladislav Bolkhovitin & Leonid Stoljar");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SCSI disk (type 0) and CDROM (type 5) dev handler for "
+	"SCST using files on file systems or block devices");
+MODULE_VERSION(SCST_VERSION_STRING);


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