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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2013 Shaohua Li <shli@kernel.org>
  * Copyright (C) 2014 Red Hat, Inc.
  * Copyright (C) 2015 Arrikto, Inc.
  * Copyright (C) 2017 Chinamobile, Inc.
  */
 
 #include <linux/spinlock.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/timer.h>
 #include <linux/parser.h>
 #include <linux/vmalloc.h>
 #include <linux/uio_driver.h>
 #include <linux/xarray.h>
 #include <linux/stringify.h>
 #include <linux/bitops.h>
 #include <linux/highmem.h>
 #include <linux/configfs.h>
 #include <linux/mutex.h>
 #include <linux/workqueue.h>
 #include <linux/pagemap.h>
 #include <net/genetlink.h>
 #include <scsi/scsi_common.h>
 #include <scsi/scsi_proto.h>
 #include <target/target_core_base.h>
 #include <target/target_core_fabric.h>
 #include <target/target_core_backend.h>
 
 #include <linux/target_core_user.h>
 
 /**
  * DOC: Userspace I/O
  * Userspace I/O
  * -------------
  *
  * Define a shared-memory interface for LIO to pass SCSI commands and
  * data to userspace for processing. This is to allow backends that
  * are too complex for in-kernel support to be possible.
  *
  * It uses the UIO framework to do a lot of the device-creation and
  * introspection work for us.
  *
  * See the .h file for how the ring is laid out. Note that while the
  * command ring is defined, the particulars of the data area are
  * not. Offset values in the command entry point to other locations
  * internal to the mmap-ed area. There is separate space outside the
  * command ring for data buffers. This leaves maximum flexibility for
  * moving buffer allocations, or even page flipping or other
  * allocation techniques, without altering the command ring layout.
  *
  * SECURITY:
  * The user process must be assumed to be malicious. There's no way to
  * prevent it breaking the command ring protocol if it wants, but in
  * order to prevent other issues we must only ever read *data* from
  * the shared memory area, not offsets or sizes. This applies to
  * command ring entries as well as the mailbox. Extra code needed for
  * this may have a 'UAM' comment.
  */
 
 #define TCMU_TIME_OUT (30 * MSEC_PER_SEC)
 
 /* For mailbox plus cmd ring, the size is fixed 8MB */
 #define MB_CMDR_SIZE_DEF (8 * 1024 * 1024)
 /* Offset of cmd ring is size of mailbox */
 #define CMDR_OFF ((__u32)sizeof(struct tcmu_mailbox))
 #define CMDR_SIZE_DEF (MB_CMDR_SIZE_DEF - CMDR_OFF)
 
 /*
  * For data area, the default block size is PAGE_SIZE and
  * the default total size is 256K * PAGE_SIZE.
  */
 #define DATA_PAGES_PER_BLK_DEF 1
 #define DATA_AREA_PAGES_DEF (256 * 1024)
 
 #define TCMU_MBS_TO_PAGES(_mbs) ((size_t)_mbs << (20 - PAGE_SHIFT))
 #define TCMU_PAGES_TO_MBS(_pages) (_pages >> (20 - PAGE_SHIFT))
 
 /*
  * Default number of global data blocks(512K * PAGE_SIZE)
  * when the unmap thread will be started.
  */
 #define TCMU_GLOBAL_MAX_PAGES_DEF (512 * 1024)
 
 static u8 tcmu_kern_cmd_reply_supported;
 static u8 tcmu_netlink_blocked;
 
 static struct device *tcmu_root_device;
 
 struct tcmu_hba {
     u32 host_id;
 };
 
 #define TCMU_CONFIG_LEN 256
 
 static DEFINE_MUTEX(tcmu_nl_cmd_mutex);
 static LIST_HEAD(tcmu_nl_cmd_list);
 
 struct tcmu_dev;
 
 struct tcmu_nl_cmd {
     /* wake up thread waiting for reply */
     struct completion complete;
     struct list_head nl_list;
     struct tcmu_dev *udev;
     int cmd;
     int status;
 };
 
 struct tcmu_dev {
     struct list_head node;
     struct kref kref;
 
     struct se_device se_dev;
     struct se_dev_plug se_plug;
 
     char *name;
     struct se_hba *hba;
 
 #define TCMU_DEV_BIT_OPEN 0
 #define TCMU_DEV_BIT_BROKEN 1
 #define TCMU_DEV_BIT_BLOCKED 2
 #define TCMU_DEV_BIT_TMR_NOTIFY 3
 #define TCMU_DEV_BIT_PLUGGED 4
     unsigned long flags;
 
     struct uio_info uio_info;
 
     struct inode *inode;
 
     uint64_t dev_size;
 
     struct tcmu_mailbox *mb_addr;
     void *cmdr;
     u32 cmdr_size;
     u32 cmdr_last_cleaned;
     /* Offset of data area from start of mb */
     /* Must add data_off and mb_addr to get the address */
     size_t data_off;
     int data_area_mb;
     uint32_t max_blocks;
     size_t mmap_pages;
 
     struct mutex cmdr_lock;
     struct list_head qfull_queue;
     struct list_head tmr_queue;
 
     uint32_t dbi_max;
     uint32_t dbi_thresh;
     unsigned long *data_bitmap;
     struct xarray data_pages;
     uint32_t data_pages_per_blk;
     uint32_t data_blk_size;
 
     struct xarray commands;
 
     struct timer_list cmd_timer;
     unsigned int cmd_time_out;
     struct list_head inflight_queue;
 
     struct timer_list qfull_timer;
     int qfull_time_out;
 
     struct list_head timedout_entry;
 
     struct tcmu_nl_cmd curr_nl_cmd;
 
     char dev_config[TCMU_CONFIG_LEN];
 
     int nl_reply_supported;
 };
 
 #define TCMU_DEV(_se_dev) container_of(_se_dev, struct tcmu_dev, se_dev)
 
 struct tcmu_cmd {
     struct se_cmd *se_cmd;
     struct tcmu_dev *tcmu_dev;
     struct list_head queue_entry;
 
     uint16_t cmd_id;
 
     /* Can't use se_cmd when cleaning up expired cmds, because if
        cmd has been completed then accessing se_cmd is off limits */
     uint32_t dbi_cnt;
     uint32_t dbi_bidi_cnt;
     uint32_t dbi_cur;
     uint32_t *dbi;
 
     uint32_t data_len_bidi;
 
     unsigned long deadline;
 
 #define TCMU_CMD_BIT_EXPIRED 0
 #define TCMU_CMD_BIT_KEEP_BUF 1
     unsigned long flags;
 };
 
 struct tcmu_tmr {
     struct list_head queue_entry;
 
     uint8_t tmr_type;
     uint32_t tmr_cmd_cnt;
     int16_t tmr_cmd_ids[];
 };
 
 /*
  * To avoid dead lock the mutex lock order should always be:
  *
  * mutex_lock(&root_udev_mutex);
  * ...
  * mutex_lock(&tcmu_dev->cmdr_lock);
  * mutex_unlock(&tcmu_dev->cmdr_lock);
  * ...
  * mutex_unlock(&root_udev_mutex);
  */
 static DEFINE_MUTEX(root_udev_mutex);
 static LIST_HEAD(root_udev);
 
 static DEFINE_SPINLOCK(timed_out_udevs_lock);
 static LIST_HEAD(timed_out_udevs);
 
 static struct kmem_cache *tcmu_cmd_cache;
 
 static atomic_t global_page_count = ATOMIC_INIT(0);
 static struct delayed_work tcmu_unmap_work;
 static int tcmu_global_max_pages = TCMU_GLOBAL_MAX_PAGES_DEF;
 
 static int tcmu_set_global_max_data_area(const char *str,
                      const struct kernel_param *kp)
 {
     int ret, max_area_mb;
 
     ret = kstrtoint(str, 10, &max_area_mb);
     if (ret)
         return -EINVAL;
 
     if (max_area_mb <= 0) {
         pr_err("global_max_data_area must be larger than 0.\n");
         return -EINVAL;
     }
 
     tcmu_global_max_pages = TCMU_MBS_TO_PAGES(max_area_mb);
     if (atomic_read(&global_page_count) > tcmu_global_max_pages)
         schedule_delayed_work(&tcmu_unmap_work, 0);
     else
         cancel_delayed_work_sync(&tcmu_unmap_work);
 
     return 0;
 }
 
 static int tcmu_get_global_max_data_area(char *buffer,
                      const struct kernel_param *kp)
 {
     return sprintf(buffer, "%d\n", TCMU_PAGES_TO_MBS(tcmu_global_max_pages));
 }
 
 static const struct kernel_param_ops tcmu_global_max_data_area_op = {
     .set = tcmu_set_global_max_data_area,
     .get = tcmu_get_global_max_data_area,
 };
 
 module_param_cb(global_max_data_area_mb, &tcmu_global_max_data_area_op, NULL,
         S_IWUSR | S_IRUGO);
 MODULE_PARM_DESC(global_max_data_area_mb,
          "Max MBs allowed to be allocated to all the tcmu device's "
          "data areas.");
 
 static int tcmu_get_block_netlink(char *buffer,
                   const struct kernel_param *kp)
 {
     return sprintf(buffer, "%s\n", tcmu_netlink_blocked ?
                "blocked" : "unblocked");
 }
 
 static int tcmu_set_block_netlink(const char *str,
                   const struct kernel_param *kp)
 {
     int ret;
     u8 val;
 
     ret = kstrtou8(str, 0, &val);
     if (ret < 0)
         return ret;
 
     if (val > 1) {
         pr_err("Invalid block netlink value %u\n", val);
         return -EINVAL;
     }
 
     tcmu_netlink_blocked = val;
     return 0;
 }
 
 static const struct kernel_param_ops tcmu_block_netlink_op = {
     .set = tcmu_set_block_netlink,
     .get = tcmu_get_block_netlink,
 };
 
 module_param_cb(block_netlink, &tcmu_block_netlink_op, NULL, S_IWUSR | S_IRUGO);
 MODULE_PARM_DESC(block_netlink, "Block new netlink commands.");
 
 static int tcmu_fail_netlink_cmd(struct tcmu_nl_cmd *nl_cmd)
 {
     struct tcmu_dev *udev = nl_cmd->udev;
 
     if (!tcmu_netlink_blocked) {
         pr_err("Could not reset device's netlink interface. Netlink is not blocked.\n");
         return -EBUSY;
     }
 
     if (nl_cmd->cmd != TCMU_CMD_UNSPEC) {
         pr_debug("Aborting nl cmd %d on %s\n", nl_cmd->cmd, udev->name);
         nl_cmd->status = -EINTR;
         list_del(&nl_cmd->nl_list);
         complete(&nl_cmd->complete);
     }
     return 0;
 }
 
 static int tcmu_set_reset_netlink(const char *str,
                   const struct kernel_param *kp)
 {
     struct tcmu_nl_cmd *nl_cmd, *tmp_cmd;
     int ret;
     u8 val;
 
     ret = kstrtou8(str, 0, &val);
     if (ret < 0)
         return ret;
 
     if (val != 1) {
         pr_err("Invalid reset netlink value %u\n", val);
         return -EINVAL;
     }
 
     mutex_lock(&tcmu_nl_cmd_mutex);
     list_for_each_entry_safe(nl_cmd, tmp_cmd, &tcmu_nl_cmd_list, nl_list) {
         ret = tcmu_fail_netlink_cmd(nl_cmd);
         if (ret)
             break;
     }
     mutex_unlock(&tcmu_nl_cmd_mutex);
 
     return ret;
 }
 
 static const struct kernel_param_ops tcmu_reset_netlink_op = {
     .set = tcmu_set_reset_netlink,
 };
 
 module_param_cb(reset_netlink, &tcmu_reset_netlink_op, NULL, S_IWUSR);
 MODULE_PARM_DESC(reset_netlink, "Reset netlink commands.");
 
 /* multicast group */
 enum tcmu_multicast_groups {
     TCMU_MCGRP_CONFIG,
 };
 
 static const struct genl_multicast_group tcmu_mcgrps[] = {
     [TCMU_MCGRP_CONFIG] = { .name = "config", },
 };
 
 static struct nla_policy tcmu_attr_policy[TCMU_ATTR_MAX+1] = {
     [TCMU_ATTR_DEVICE]  = { .type = NLA_STRING },
     [TCMU_ATTR_MINOR]   = { .type = NLA_U32 },
     [TCMU_ATTR_CMD_STATUS]  = { .type = NLA_S32 },
     [TCMU_ATTR_DEVICE_ID]   = { .type = NLA_U32 },
     [TCMU_ATTR_SUPP_KERN_CMD_REPLY] = { .type = NLA_U8 },
 };
 
 static int tcmu_genl_cmd_done(struct genl_info *info, int completed_cmd)
 {
     struct tcmu_dev *udev = NULL;
     struct tcmu_nl_cmd *nl_cmd;
     int dev_id, rc, ret = 0;
 
     if (!info->attrs[TCMU_ATTR_CMD_STATUS] ||
         !info->attrs[TCMU_ATTR_DEVICE_ID]) {
         printk(KERN_ERR "TCMU_ATTR_CMD_STATUS or TCMU_ATTR_DEVICE_ID not set, doing nothing\n");
         return -EINVAL;
         }
 
     dev_id = nla_get_u32(info->attrs[TCMU_ATTR_DEVICE_ID]);
     rc = nla_get_s32(info->attrs[TCMU_ATTR_CMD_STATUS]);
 
     mutex_lock(&tcmu_nl_cmd_mutex);
     list_for_each_entry(nl_cmd, &tcmu_nl_cmd_list, nl_list) {
         if (nl_cmd->udev->se_dev.dev_index == dev_id) {
             udev = nl_cmd->udev;
             break;
         }
     }
 
     if (!udev) {
         pr_err("tcmu nl cmd %u/%d completion could not find device with dev id %u.\n",
                completed_cmd, rc, dev_id);
         ret = -ENODEV;
         goto unlock;
     }
     list_del(&nl_cmd->nl_list);
 
     pr_debug("%s genl cmd done got id %d curr %d done %d rc %d stat %d\n",
          udev->name, dev_id, nl_cmd->cmd, completed_cmd, rc,
          nl_cmd->status);
 
     if (nl_cmd->cmd != completed_cmd) {
         pr_err("Mismatched commands on %s (Expecting reply for %d. Current %d).\n",
                udev->name, completed_cmd, nl_cmd->cmd);
         ret = -EINVAL;
         goto unlock;
     }
 
     nl_cmd->status = rc;
     complete(&nl_cmd->complete);
 unlock:
     mutex_unlock(&tcmu_nl_cmd_mutex);
     return ret;
 }
 
 static int tcmu_genl_rm_dev_done(struct sk_buff *skb, struct genl_info *info)
 {
     return tcmu_genl_cmd_done(info, TCMU_CMD_REMOVED_DEVICE);
 }
 
 static int tcmu_genl_add_dev_done(struct sk_buff *skb, struct genl_info *info)
 {
     return tcmu_genl_cmd_done(info, TCMU_CMD_ADDED_DEVICE);
 }
 
 static int tcmu_genl_reconfig_dev_done(struct sk_buff *skb,
                        struct genl_info *info)
 {
     return tcmu_genl_cmd_done(info, TCMU_CMD_RECONFIG_DEVICE);
 }
 
 static int tcmu_genl_set_features(struct sk_buff *skb, struct genl_info *info)
 {
     if (info->attrs[TCMU_ATTR_SUPP_KERN_CMD_REPLY]) {
         tcmu_kern_cmd_reply_supported  =
             nla_get_u8(info->attrs[TCMU_ATTR_SUPP_KERN_CMD_REPLY]);
         printk(KERN_INFO "tcmu daemon: command reply support %u.\n",
                tcmu_kern_cmd_reply_supported);
     }
 
     return 0;
 }
 
 static const struct genl_small_ops tcmu_genl_ops[] = {
     {
         .cmd    = TCMU_CMD_SET_FEATURES,
         .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
         .flags  = GENL_ADMIN_PERM,
         .doit   = tcmu_genl_set_features,
     },
     {
         .cmd    = TCMU_CMD_ADDED_DEVICE_DONE,
         .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
         .flags  = GENL_ADMIN_PERM,
         .doit   = tcmu_genl_add_dev_done,
     },
     {
         .cmd    = TCMU_CMD_REMOVED_DEVICE_DONE,
         .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
         .flags  = GENL_ADMIN_PERM,
         .doit   = tcmu_genl_rm_dev_done,
     },
     {
         .cmd    = TCMU_CMD_RECONFIG_DEVICE_DONE,
         .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
         .flags  = GENL_ADMIN_PERM,
         .doit   = tcmu_genl_reconfig_dev_done,
     },
 };
 
 /* Our generic netlink family */
 static struct genl_family tcmu_genl_family __ro_after_init = {
     .module = THIS_MODULE,
     .hdrsize = 0,
     .name = "TCM-USER",
     .version = 2,
     .maxattr = TCMU_ATTR_MAX,
     .policy = tcmu_attr_policy,
     .mcgrps = tcmu_mcgrps,
     .n_mcgrps = ARRAY_SIZE(tcmu_mcgrps),
     .netnsok = true,
     .small_ops = tcmu_genl_ops,
     .n_small_ops = ARRAY_SIZE(tcmu_genl_ops),
 };
 
 #define tcmu_cmd_set_dbi_cur(cmd, index) ((cmd)->dbi_cur = (index))
 #define tcmu_cmd_reset_dbi_cur(cmd) tcmu_cmd_set_dbi_cur(cmd, 0)
 #define tcmu_cmd_set_dbi(cmd, index) ((cmd)->dbi[(cmd)->dbi_cur++] = (index))
 #define tcmu_cmd_get_dbi(cmd) ((cmd)->dbi[(cmd)->dbi_cur++])
 
 static void tcmu_cmd_free_data(struct tcmu_cmd *tcmu_cmd, uint32_t len)
 {
     struct tcmu_dev *udev = tcmu_cmd->tcmu_dev;
     uint32_t i;
 
     for (i = 0; i < len; i++)
         clear_bit(tcmu_cmd->dbi[i], udev->data_bitmap);
 }
 
 static inline int tcmu_get_empty_block(struct tcmu_dev *udev,
                        struct tcmu_cmd *tcmu_cmd,
                        int prev_dbi, int length, int *iov_cnt)
 {
     XA_STATE(xas, &udev->data_pages, 0);
     struct page *page;
     int i, cnt, dbi, dpi;
     int page_cnt = DIV_ROUND_UP(length, PAGE_SIZE);
 
     dbi = find_first_zero_bit(udev->data_bitmap, udev->dbi_thresh);
     if (dbi == udev->dbi_thresh)
         return -1;
 
     dpi = dbi * udev->data_pages_per_blk;
     /* Count the number of already allocated pages */
     xas_set(&xas, dpi);
     rcu_read_lock();
     for (cnt = 0; xas_next(&xas) && cnt < page_cnt;)
         cnt++;
     rcu_read_unlock();
 
     for (i = cnt; i < page_cnt; i++) {
         /* try to get new zeroed page from the mm */
         page = alloc_page(GFP_NOIO | __GFP_ZERO);
         if (!page)
             break;
 
         if (xa_store(&udev->data_pages, dpi + i, page, GFP_NOIO)) {
             __free_page(page);
             break;
         }
     }
     if (atomic_add_return(i - cnt, &global_page_count) >
                   tcmu_global_max_pages)
         schedule_delayed_work(&tcmu_unmap_work, 0);
 
     if (i && dbi > udev->dbi_max)
         udev->dbi_max = dbi;
 
     set_bit(dbi, udev->data_bitmap);
     tcmu_cmd_set_dbi(tcmu_cmd, dbi);
 
     if (dbi != prev_dbi + 1)
         *iov_cnt += 1;
 
     return i == page_cnt ? dbi : -1;
 }
 
 static int tcmu_get_empty_blocks(struct tcmu_dev *udev,
                  struct tcmu_cmd *tcmu_cmd, int length)
 {
     /* start value of dbi + 1 must not be a valid dbi */
     int dbi = -2;
     int blk_data_len, iov_cnt = 0;
     uint32_t blk_size = udev->data_blk_size;
 
     for (; length > 0; length -= blk_size) {
         blk_data_len = min_t(uint32_t, length, blk_size);
         dbi = tcmu_get_empty_block(udev, tcmu_cmd, dbi, blk_data_len,
                        &iov_cnt);
         if (dbi < 0)
             return -1;
     }
     return iov_cnt;
 }
 
 static inline void tcmu_free_cmd(struct tcmu_cmd *tcmu_cmd)
 {
     kfree(tcmu_cmd->dbi);
     kmem_cache_free(tcmu_cmd_cache, tcmu_cmd);
 }
 
 static inline void tcmu_cmd_set_block_cnts(struct tcmu_cmd *cmd)
 {
     int i, len;
     struct se_cmd *se_cmd = cmd->se_cmd;
     uint32_t blk_size = cmd->tcmu_dev->data_blk_size;
 
     cmd->dbi_cnt = DIV_ROUND_UP(se_cmd->data_length, blk_size);
 
     if (se_cmd->se_cmd_flags & SCF_BIDI) {
         BUG_ON(!(se_cmd->t_bidi_data_sg && se_cmd->t_bidi_data_nents));
         for (i = 0, len = 0; i < se_cmd->t_bidi_data_nents; i++)
             len += se_cmd->t_bidi_data_sg[i].length;
         cmd->dbi_bidi_cnt = DIV_ROUND_UP(len, blk_size);
         cmd->dbi_cnt += cmd->dbi_bidi_cnt;
         cmd->data_len_bidi = len;
     }
 }
 
 static int new_block_to_iov(struct tcmu_dev *udev, struct tcmu_cmd *cmd,
                 struct iovec **iov, int prev_dbi, int len)
 {
     /* Get the next dbi */
     int dbi = tcmu_cmd_get_dbi(cmd);
 
     /* Do not add more than udev->data_blk_size to iov */
     len = min_t(int,  len, udev->data_blk_size);
 
     /*
      * The following code will gather and map the blocks to the same iovec
      * when the blocks are all next to each other.
      */
     if (dbi != prev_dbi + 1) {
         /* dbi is not next to previous dbi, so start new iov */
         if (prev_dbi >= 0)
             (*iov)++;
         /* write offset relative to mb_addr */
         (*iov)->iov_base = (void __user *)
                    (udev->data_off + dbi * udev->data_blk_size);
     }
     (*iov)->iov_len += len;
 
     return dbi;
 }
 
 static void tcmu_setup_iovs(struct tcmu_dev *udev, struct tcmu_cmd *cmd,
                 struct iovec **iov, int data_length)
 {
     /* start value of dbi + 1 must not be a valid dbi */
     int dbi = -2;
 
     /* We prepare the IOVs for DMA_FROM_DEVICE transfer direction */
     for (; data_length > 0; data_length -= udev->data_blk_size)
         dbi = new_block_to_iov(udev, cmd, iov, dbi, data_length);
 }
 
 static struct tcmu_cmd *tcmu_alloc_cmd(struct se_cmd *se_cmd)
 {
     struct se_device *se_dev = se_cmd->se_dev;
     struct tcmu_dev *udev = TCMU_DEV(se_dev);
     struct tcmu_cmd *tcmu_cmd;
 
     tcmu_cmd = kmem_cache_zalloc(tcmu_cmd_cache, GFP_NOIO);
     if (!tcmu_cmd)
         return NULL;
 
     INIT_LIST_HEAD(&tcmu_cmd->queue_entry);
     tcmu_cmd->se_cmd = se_cmd;
     tcmu_cmd->tcmu_dev = udev;
 
     tcmu_cmd_set_block_cnts(tcmu_cmd);
     tcmu_cmd->dbi = kcalloc(tcmu_cmd->dbi_cnt, sizeof(uint32_t),
                 GFP_NOIO);
     if (!tcmu_cmd->dbi) {
         kmem_cache_free(tcmu_cmd_cache, tcmu_cmd);
         return NULL;
     }
 
     return tcmu_cmd;
 }
 
 static inline void tcmu_flush_dcache_range(void *vaddr, size_t size)
 {
     unsigned long offset = offset_in_page(vaddr);
     void *start = vaddr - offset;
 
     size = round_up(size+offset, PAGE_SIZE);
 
     while (size) {
         flush_dcache_page(vmalloc_to_page(start));
         start += PAGE_SIZE;
         size -= PAGE_SIZE;
     }
 }
 
 /*
  * Some ring helper functions. We don't assume size is a power of 2 so
  * we can't use circ_buf.h.
  */
 static inline size_t spc_used(size_t head, size_t tail, size_t size)
 {
     int diff = head - tail;
 
     if (diff >= 0)
         return diff;
     else
         return size + diff;
 }
 
 static inline size_t spc_free(size_t head, size_t tail, size_t size)
 {
     /* Keep 1 byte unused or we can't tell full from empty */
     return (size - spc_used(head, tail, size) - 1);
 }
 
 static inline size_t head_to_end(size_t head, size_t size)
 {
     return size - head;
 }
 
 #define UPDATE_HEAD(head, used, size) smp_store_release(&head, ((head % size) + used) % size)
 
 #define TCMU_SG_TO_DATA_AREA 1
 #define TCMU_DATA_AREA_TO_SG 2
 
 static inline void tcmu_copy_data(struct tcmu_dev *udev,
                   struct tcmu_cmd *tcmu_cmd, uint32_t direction,
                   struct scatterlist *sg, unsigned int sg_nents,
                   struct iovec **iov, size_t data_len)
 {
     /* start value of dbi + 1 must not be a valid dbi */
     int dbi = -2;
     size_t page_remaining, cp_len;
     int page_cnt, page_inx, dpi;
     struct sg_mapping_iter sg_iter;
     unsigned int sg_flags;
     struct page *page;
     void *data_page_start, *data_addr;
 
     if (direction == TCMU_SG_TO_DATA_AREA)
         sg_flags = SG_MITER_ATOMIC | SG_MITER_FROM_SG;
     else
         sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
     sg_miter_start(&sg_iter, sg, sg_nents, sg_flags);
 
     while (data_len) {
         if (direction == TCMU_SG_TO_DATA_AREA)
             dbi = new_block_to_iov(udev, tcmu_cmd, iov, dbi,
                            data_len);
         else
             dbi = tcmu_cmd_get_dbi(tcmu_cmd);
 
         page_cnt = DIV_ROUND_UP(data_len, PAGE_SIZE);
         if (page_cnt > udev->data_pages_per_blk)
             page_cnt = udev->data_pages_per_blk;
 
         dpi = dbi * udev->data_pages_per_blk;
         for (page_inx = 0; page_inx < page_cnt && data_len;
              page_inx++, dpi++) {
             page = xa_load(&udev->data_pages, dpi);
 
             if (direction == TCMU_DATA_AREA_TO_SG)
                 flush_dcache_page(page);
             data_page_start = kmap_atomic(page);
             page_remaining = PAGE_SIZE;
 
             while (page_remaining && data_len) {
                 if (!sg_miter_next(&sg_iter)) {
                     /* set length to 0 to abort outer loop */
                     data_len = 0;
                     pr_debug("%s: aborting data copy due to exhausted sg_list\n",
                          __func__);
                     break;
                 }
                 cp_len = min3(sg_iter.length, page_remaining,
                           data_len);
 
                 data_addr = data_page_start +
                         PAGE_SIZE - page_remaining;
                 if (direction == TCMU_SG_TO_DATA_AREA)
                     memcpy(data_addr, sg_iter.addr, cp_len);
                 else
                     memcpy(sg_iter.addr, data_addr, cp_len);
 
                 data_len -= cp_len;
                 page_remaining -= cp_len;
                 sg_iter.consumed = cp_len;
             }
             sg_miter_stop(&sg_iter);
 
             kunmap_atomic(data_page_start);
             if (direction == TCMU_SG_TO_DATA_AREA)
                 flush_dcache_page(page);
         }
     }
 }
 
 static void scatter_data_area(struct tcmu_dev *udev, struct tcmu_cmd *tcmu_cmd,
                   struct iovec **iov)
 {
     struct se_cmd *se_cmd = tcmu_cmd->se_cmd;
 
     tcmu_copy_data(udev, tcmu_cmd, TCMU_SG_TO_DATA_AREA, se_cmd->t_data_sg,
                se_cmd->t_data_nents, iov, se_cmd->data_length);
 }
 
 static void gather_data_area(struct tcmu_dev *udev, struct tcmu_cmd *tcmu_cmd,
                  bool bidi, uint32_t read_len)
 {
     struct se_cmd *se_cmd = tcmu_cmd->se_cmd;
     struct scatterlist *data_sg;
     unsigned int data_nents;
 
     if (!bidi) {
         data_sg = se_cmd->t_data_sg;
         data_nents = se_cmd->t_data_nents;
     } else {
         /*
          * For bidi case, the first count blocks are for Data-Out
          * buffer blocks, and before gathering the Data-In buffer
          * the Data-Out buffer blocks should be skipped.
          */
         tcmu_cmd_set_dbi_cur(tcmu_cmd,
                      tcmu_cmd->dbi_cnt - tcmu_cmd->dbi_bidi_cnt);
 
         data_sg = se_cmd->t_bidi_data_sg;
         data_nents = se_cmd->t_bidi_data_nents;
     }
 
     tcmu_copy_data(udev, tcmu_cmd, TCMU_DATA_AREA_TO_SG, data_sg,
                data_nents, NULL, read_len);
 }
 
 static inline size_t spc_bitmap_free(unsigned long *bitmap, uint32_t thresh)
 {
     return thresh - bitmap_weight(bitmap, thresh);
 }
 
 /*
  * We can't queue a command until we have space available on the cmd ring.
  *
  * Called with ring lock held.
  */
 static bool is_ring_space_avail(struct tcmu_dev *udev, size_t cmd_size)
 {
     struct tcmu_mailbox *mb = udev->mb_addr;
     size_t space, cmd_needed;
     u32 cmd_head;
 
     tcmu_flush_dcache_range(mb, sizeof(*mb));
 
     cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
 
     /*
      * If cmd end-of-ring space is too small then we need space for a NOP plus
      * original cmd - cmds are internally contiguous.
      */
     if (head_to_end(cmd_head, udev->cmdr_size) >= cmd_size)
         cmd_needed = cmd_size;
     else
         cmd_needed = cmd_size + head_to_end(cmd_head, udev->cmdr_size);
 
     space = spc_free(cmd_head, udev->cmdr_last_cleaned, udev->cmdr_size);
     if (space < cmd_needed) {
         pr_debug("no cmd space: %u %u %u\n", cmd_head,
                udev->cmdr_last_cleaned, udev->cmdr_size);
         return false;
     }
     return true;
 }
 
 /*
  * We have to allocate data buffers before we can queue a command.
  * Returns -1 on error (not enough space) or number of needed iovs on success
  *
  * Called with ring lock held.
  */
 static int tcmu_alloc_data_space(struct tcmu_dev *udev, struct tcmu_cmd *cmd,
                   int *iov_bidi_cnt)
 {
     int space, iov_cnt = 0, ret = 0;
 
     if (!cmd->dbi_cnt)
         goto wr_iov_cnts;
 
     /* try to check and get the data blocks as needed */
     space = spc_bitmap_free(udev->data_bitmap, udev->dbi_thresh);
     if (space < cmd->dbi_cnt) {
         unsigned long blocks_left =
                 (udev->max_blocks - udev->dbi_thresh) + space;
 
         if (blocks_left < cmd->dbi_cnt) {
             pr_debug("no data space: only %lu available, but ask for %u\n",
                     blocks_left * udev->data_blk_size,
                     cmd->dbi_cnt * udev->data_blk_size);
             return -1;
         }
 
         udev->dbi_thresh += cmd->dbi_cnt;
         if (udev->dbi_thresh > udev->max_blocks)
             udev->dbi_thresh = udev->max_blocks;
     }
 
     iov_cnt = tcmu_get_empty_blocks(udev, cmd, cmd->se_cmd->data_length);
     if (iov_cnt < 0)
         return -1;
 
     if (cmd->dbi_bidi_cnt) {
         ret = tcmu_get_empty_blocks(udev, cmd, cmd->data_len_bidi);
         if (ret < 0)
             return -1;
     }
 wr_iov_cnts:
     *iov_bidi_cnt = ret;
     return iov_cnt + ret;
 }
 
 static inline size_t tcmu_cmd_get_base_cmd_size(size_t iov_cnt)
 {
     return max(offsetof(struct tcmu_cmd_entry, req.iov[iov_cnt]),
             sizeof(struct tcmu_cmd_entry));
 }
 
 static inline size_t tcmu_cmd_get_cmd_size(struct tcmu_cmd *tcmu_cmd,
                        size_t base_command_size)
 {
     struct se_cmd *se_cmd = tcmu_cmd->se_cmd;
     size_t command_size;
 
     command_size = base_command_size +
         round_up(scsi_command_size(se_cmd->t_task_cdb),
                 TCMU_OP_ALIGN_SIZE);
 
     WARN_ON(command_size & (TCMU_OP_ALIGN_SIZE-1));
 
     return command_size;
 }
 
 static void tcmu_setup_cmd_timer(struct tcmu_cmd *tcmu_cmd, unsigned int tmo,
                  struct timer_list *timer)
 {
     if (!tmo)
         return;
 
     tcmu_cmd->deadline = round_jiffies_up(jiffies + msecs_to_jiffies(tmo));
     if (!timer_pending(timer))
         mod_timer(timer, tcmu_cmd->deadline);
 
     pr_debug("Timeout set up for cmd %p, dev = %s, tmo = %lu\n", tcmu_cmd,
          tcmu_cmd->tcmu_dev->name, tmo / MSEC_PER_SEC);
 }
 
 static int add_to_qfull_queue(struct tcmu_cmd *tcmu_cmd)
 {
     struct tcmu_dev *udev = tcmu_cmd->tcmu_dev;
     unsigned int tmo;
 
     /*
      * For backwards compat if qfull_time_out is not set use
      * cmd_time_out and if that's not set use the default time out.
      */
     if (!udev->qfull_time_out)
         return -ETIMEDOUT;
     else if (udev->qfull_time_out > 0)
         tmo = udev->qfull_time_out;
     else if (udev->cmd_time_out)
         tmo = udev->cmd_time_out;
     else
         tmo = TCMU_TIME_OUT;
 
     tcmu_setup_cmd_timer(tcmu_cmd, tmo, &udev->qfull_timer);
 
     list_add_tail(&tcmu_cmd->queue_entry, &udev->qfull_queue);
     pr_debug("adding cmd %p on dev %s to ring space wait queue\n",
          tcmu_cmd, udev->name);
     return 0;
 }
 
 static uint32_t ring_insert_padding(struct tcmu_dev *udev, size_t cmd_size)
 {
     struct tcmu_cmd_entry_hdr *hdr;
     struct tcmu_mailbox *mb = udev->mb_addr;
     uint32_t cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
 
     /* Insert a PAD if end-of-ring space is too small */
     if (head_to_end(cmd_head, udev->cmdr_size) < cmd_size) {
         size_t pad_size = head_to_end(cmd_head, udev->cmdr_size);
 
         hdr = udev->cmdr + cmd_head;
         tcmu_hdr_set_op(&hdr->len_op, TCMU_OP_PAD);
         tcmu_hdr_set_len(&hdr->len_op, pad_size);
         hdr->cmd_id = 0; /* not used for PAD */
         hdr->kflags = 0;
         hdr->uflags = 0;
         tcmu_flush_dcache_range(hdr, sizeof(*hdr));
 
         UPDATE_HEAD(mb->cmd_head, pad_size, udev->cmdr_size);
         tcmu_flush_dcache_range(mb, sizeof(*mb));
 
         cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
         WARN_ON(cmd_head != 0);
     }
 
     return cmd_head;
 }
 
 static void tcmu_unplug_device(struct se_dev_plug *se_plug)
 {
     struct se_device *se_dev = se_plug->se_dev;
     struct tcmu_dev *udev = TCMU_DEV(se_dev);
 
     clear_bit(TCMU_DEV_BIT_PLUGGED, &udev->flags);
     uio_event_notify(&udev->uio_info);
 }
 
 static struct se_dev_plug *tcmu_plug_device(struct se_device *se_dev)
 {
     struct tcmu_dev *udev = TCMU_DEV(se_dev);
 
     if (!test_and_set_bit(TCMU_DEV_BIT_PLUGGED, &udev->flags))
         return &udev->se_plug;
 
     return NULL;
 }
 
 /**
  * queue_cmd_ring - queue cmd to ring or internally
  * @tcmu_cmd: cmd to queue
  * @scsi_err: TCM error code if failure (-1) returned.
  *
  * Returns:
  * -1 we cannot queue internally or to the ring.
  *  0 success
  *  1 internally queued to wait for ring memory to free.
  */
 static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err)
 {
     struct tcmu_dev *udev = tcmu_cmd->tcmu_dev;
     struct se_cmd *se_cmd = tcmu_cmd->se_cmd;
     size_t base_command_size, command_size;
     struct tcmu_mailbox *mb = udev->mb_addr;
     struct tcmu_cmd_entry *entry;
     struct iovec *iov;
     int iov_cnt, iov_bidi_cnt;
     uint32_t cmd_id, cmd_head;
     uint64_t cdb_off;
     uint32_t blk_size = udev->data_blk_size;
     /* size of data buffer needed */
     size_t data_length = (size_t)tcmu_cmd->dbi_cnt * blk_size;
 
     *scsi_err = TCM_NO_SENSE;
 
     if (test_bit(TCMU_DEV_BIT_BLOCKED, &udev->flags)) {
         *scsi_err = TCM_LUN_BUSY;
         return -1;
     }
 
     if (test_bit(TCMU_DEV_BIT_BROKEN, &udev->flags)) {
         *scsi_err = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
         return -1;
     }
 
     if (!list_empty(&udev->qfull_queue))
         goto queue;
 
     if (data_length > (size_t)udev->max_blocks * blk_size) {
         pr_warn("TCMU: Request of size %zu is too big for %zu data area\n",
             data_length, (size_t)udev->max_blocks * blk_size);
         *scsi_err = TCM_INVALID_CDB_FIELD;
         return -1;
     }
 
     iov_cnt = tcmu_alloc_data_space(udev, tcmu_cmd, &iov_bidi_cnt);
     if (iov_cnt < 0)
         goto free_and_queue;
 
     /*
      * Must be a certain minimum size for response sense info, but
      * also may be larger if the iov array is large.
      */
     base_command_size = tcmu_cmd_get_base_cmd_size(iov_cnt);
     command_size = tcmu_cmd_get_cmd_size(tcmu_cmd, base_command_size);
 
     if (command_size > (udev->cmdr_size / 2)) {
         pr_warn("TCMU: Request of size %zu is too big for %u cmd ring\n",
             command_size, udev->cmdr_size);
         tcmu_cmd_free_data(tcmu_cmd, tcmu_cmd->dbi_cur);
         *scsi_err = TCM_INVALID_CDB_FIELD;
         return -1;
     }
 
     if (!is_ring_space_avail(udev, command_size))
         /*
          * Don't leave commands partially setup because the unmap
          * thread might need the blocks to make forward progress.
          */
         goto free_and_queue;
 
     if (xa_alloc(&udev->commands, &cmd_id, tcmu_cmd, XA_LIMIT(1, 0xffff),
              GFP_NOWAIT) < 0) {
         pr_err("tcmu: Could not allocate cmd id.\n");
 
         tcmu_cmd_free_data(tcmu_cmd, tcmu_cmd->dbi_cnt);
         *scsi_err = TCM_OUT_OF_RESOURCES;
         return -1;
     }
     tcmu_cmd->cmd_id = cmd_id;
 
     pr_debug("allocated cmd id %u for cmd %p dev %s\n", tcmu_cmd->cmd_id,
          tcmu_cmd, udev->name);
 
     cmd_head = ring_insert_padding(udev, command_size);
 
     entry = udev->cmdr + cmd_head;
     memset(entry, 0, command_size);
     tcmu_hdr_set_op(&entry->hdr.len_op, TCMU_OP_CMD);
 
     /* prepare iov list and copy data to data area if necessary */
     tcmu_cmd_reset_dbi_cur(tcmu_cmd);
     iov = &entry->req.iov[0];
 
     if (se_cmd->data_direction == DMA_TO_DEVICE ||
         se_cmd->se_cmd_flags & SCF_BIDI)
         scatter_data_area(udev, tcmu_cmd, &iov);
     else
         tcmu_setup_iovs(udev, tcmu_cmd, &iov, se_cmd->data_length);
 
     entry->req.iov_cnt = iov_cnt - iov_bidi_cnt;
 
     /* Handle BIDI commands */
     if (se_cmd->se_cmd_flags & SCF_BIDI) {
         iov++;
         tcmu_setup_iovs(udev, tcmu_cmd, &iov, tcmu_cmd->data_len_bidi);
         entry->req.iov_bidi_cnt = iov_bidi_cnt;
     }
 
     tcmu_setup_cmd_timer(tcmu_cmd, udev->cmd_time_out, &udev->cmd_timer);
 
     entry->hdr.cmd_id = tcmu_cmd->cmd_id;
 
     tcmu_hdr_set_len(&entry->hdr.len_op, command_size);
 
     /* All offsets relative to mb_addr, not start of entry! */
     cdb_off = CMDR_OFF + cmd_head + base_command_size;
     memcpy((void *) mb + cdb_off, se_cmd->t_task_cdb, scsi_command_size(se_cmd->t_task_cdb));
     entry->req.cdb_off = cdb_off;
     tcmu_flush_dcache_range(entry, command_size);
 
     UPDATE_HEAD(mb->cmd_head, command_size, udev->cmdr_size);
     tcmu_flush_dcache_range(mb, sizeof(*mb));
 
     list_add_tail(&tcmu_cmd->queue_entry, &udev->inflight_queue);
 
     if (!test_bit(TCMU_DEV_BIT_PLUGGED, &udev->flags))
         uio_event_notify(&udev->uio_info);
 
     return 0;
 
 free_and_queue:
     tcmu_cmd_free_data(tcmu_cmd, tcmu_cmd->dbi_cur);
     tcmu_cmd_reset_dbi_cur(tcmu_cmd);
 
 queue:
     if (add_to_qfull_queue(tcmu_cmd)) {
         *scsi_err = TCM_OUT_OF_RESOURCES;
         return -1;
     }
 
     return 1;
 }
 
 /**
  * queue_tmr_ring - queue tmr info to ring or internally
  * @udev: related tcmu_dev
  * @tmr: tcmu_tmr containing tmr info to queue
  *
  * Returns:
  *  0 success
  *  1 internally queued to wait for ring memory to free.
  */
 static int
 queue_tmr_ring(struct tcmu_dev *udev, struct tcmu_tmr *tmr)
 {
     struct tcmu_tmr_entry *entry;
     int cmd_size;
     int id_list_sz;
     struct tcmu_mailbox *mb = udev->mb_addr;
     uint32_t cmd_head;
 
     if (test_bit(TCMU_DEV_BIT_BROKEN, &udev->flags))
         goto out_free;
 
     id_list_sz = sizeof(tmr->tmr_cmd_ids[0]) * tmr->tmr_cmd_cnt;
     cmd_size = round_up(sizeof(*entry) + id_list_sz, TCMU_OP_ALIGN_SIZE);
 
     if (!list_empty(&udev->tmr_queue) ||
         !is_ring_space_avail(udev, cmd_size)) {
         list_add_tail(&tmr->queue_entry, &udev->tmr_queue);
         pr_debug("adding tmr %p on dev %s to TMR ring space wait queue\n",
              tmr, udev->name);
         return 1;
     }
 
     cmd_head = ring_insert_padding(udev, cmd_size);
 
     entry = udev->cmdr + cmd_head;
     memset(entry, 0, cmd_size);
     tcmu_hdr_set_op(&entry->hdr.len_op, TCMU_OP_TMR);
     tcmu_hdr_set_len(&entry->hdr.len_op, cmd_size);
     entry->tmr_type = tmr->tmr_type;
     entry->cmd_cnt = tmr->tmr_cmd_cnt;
     memcpy(&entry->cmd_ids[0], &tmr->tmr_cmd_ids[0], id_list_sz);
     tcmu_flush_dcache_range(entry, cmd_size);
 
     UPDATE_HEAD(mb->cmd_head, cmd_size, udev->cmdr_size);
     tcmu_flush_dcache_range(mb, sizeof(*mb));
 
     uio_event_notify(&udev->uio_info);
 
 out_free:
     kfree(tmr);
 
     return 0;
 }
 
 static sense_reason_t
 tcmu_queue_cmd(struct se_cmd *se_cmd)
 {
     struct se_device *se_dev = se_cmd->se_dev;
     struct tcmu_dev *udev = TCMU_DEV(se_dev);
     struct tcmu_cmd *tcmu_cmd;
     sense_reason_t scsi_ret = TCM_CHECK_CONDITION_ABORT_CMD;
     int ret = -1;
 
     tcmu_cmd = tcmu_alloc_cmd(se_cmd);
     if (!tcmu_cmd)
         return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 
     mutex_lock(&udev->cmdr_lock);
     if (!(se_cmd->transport_state & CMD_T_ABORTED))
         ret = queue_cmd_ring(tcmu_cmd, &scsi_ret);
     if (ret < 0)
         tcmu_free_cmd(tcmu_cmd);
     else
         se_cmd->priv = tcmu_cmd;
     mutex_unlock(&udev->cmdr_lock);
     return scsi_ret;
 }
 
 static void tcmu_set_next_deadline(struct list_head *queue,
                    struct timer_list *timer)
 {
     struct tcmu_cmd *cmd;
 
     if (!list_empty(queue)) {
         cmd = list_first_entry(queue, struct tcmu_cmd, queue_entry);
         mod_timer(timer, cmd->deadline);
     } else
         del_timer(timer);
 }
 
 static int
 tcmu_tmr_type(enum tcm_tmreq_table tmf)
 {
     switch (tmf) {
     case TMR_ABORT_TASK:        return TCMU_TMR_ABORT_TASK;
     case TMR_ABORT_TASK_SET:    return TCMU_TMR_ABORT_TASK_SET;
     case TMR_CLEAR_ACA:     return TCMU_TMR_CLEAR_ACA;
     case TMR_CLEAR_TASK_SET:    return TCMU_TMR_CLEAR_TASK_SET;
     case TMR_LUN_RESET:     return TCMU_TMR_LUN_RESET;
     case TMR_TARGET_WARM_RESET: return TCMU_TMR_TARGET_WARM_RESET;
     case TMR_TARGET_COLD_RESET: return TCMU_TMR_TARGET_COLD_RESET;
     case TMR_LUN_RESET_PRO:     return TCMU_TMR_LUN_RESET_PRO;
     default:            return TCMU_TMR_UNKNOWN;
     }
 }
 
 static void
 tcmu_tmr_notify(struct se_device *se_dev, enum tcm_tmreq_table tmf,
         struct list_head *cmd_list)
 {
     int i = 0, cmd_cnt = 0;
     bool unqueued = false;
     struct tcmu_cmd *cmd;
     struct se_cmd *se_cmd;
     struct tcmu_tmr *tmr;
     struct tcmu_dev *udev = TCMU_DEV(se_dev);
 
     mutex_lock(&udev->cmdr_lock);
 
     /* First we check for aborted commands in qfull_queue */
     list_for_each_entry(se_cmd, cmd_list, state_list) {
         i++;
         if (!se_cmd->priv)
             continue;
         cmd = se_cmd->priv;
         /* Commands on qfull queue have no id yet */
         if (cmd->cmd_id) {
             cmd_cnt++;
             continue;
         }
         pr_debug("Removing aborted command %p from queue on dev %s.\n",
              cmd, udev->name);
 
         list_del_init(&cmd->queue_entry);
         tcmu_free_cmd(cmd);
         se_cmd->priv = NULL;
         target_complete_cmd(se_cmd, SAM_STAT_TASK_ABORTED);
         unqueued = true;
     }
     if (unqueued)
         tcmu_set_next_deadline(&udev->qfull_queue, &udev->qfull_timer);
 
     if (!test_bit(TCMU_DEV_BIT_TMR_NOTIFY, &udev->flags))
         goto unlock;
 
     pr_debug("TMR event %d on dev %s, aborted cmds %d, afflicted cmd_ids %d\n",
          tcmu_tmr_type(tmf), udev->name, i, cmd_cnt);
 
     tmr = kmalloc(struct_size(tmr, tmr_cmd_ids, cmd_cnt), GFP_NOIO);
     if (!tmr)
         goto unlock;
 
     tmr->tmr_type = tcmu_tmr_type(tmf);
     tmr->tmr_cmd_cnt = cmd_cnt;
 
     if (cmd_cnt != 0) {
         cmd_cnt = 0;
         list_for_each_entry(se_cmd, cmd_list, state_list) {
             if (!se_cmd->priv)
                 continue;
             cmd = se_cmd->priv;
             if (cmd->cmd_id)
                 tmr->tmr_cmd_ids[cmd_cnt++] = cmd->cmd_id;
         }
     }
 
     queue_tmr_ring(udev, tmr);
 
 unlock:
     mutex_unlock(&udev->cmdr_lock);
 }
 
 static bool tcmu_handle_completion(struct tcmu_cmd *cmd,
                    struct tcmu_cmd_entry *entry, bool keep_buf)
 {
     struct se_cmd *se_cmd = cmd->se_cmd;
     struct tcmu_dev *udev = cmd->tcmu_dev;
     bool read_len_valid = false;
     bool ret = true;
     uint32_t read_len;
 
     /*
      * cmd has been completed already from timeout, just reclaim
      * data area space and free cmd
      */
     if (test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags)) {
         WARN_ON_ONCE(se_cmd);
         goto out;
     }
     if (test_bit(TCMU_CMD_BIT_KEEP_BUF, &cmd->flags)) {
         pr_err("cmd_id %u already completed with KEEP_BUF, ring is broken\n",
                entry->hdr.cmd_id);
         set_bit(TCMU_DEV_BIT_BROKEN, &udev->flags);
         ret = false;
         goto out;
     }
 
     list_del_init(&cmd->queue_entry);
 
     tcmu_cmd_reset_dbi_cur(cmd);
 
     if (entry->hdr.uflags & TCMU_UFLAG_UNKNOWN_OP) {
         pr_warn("TCMU: Userspace set UNKNOWN_OP flag on se_cmd %p\n",
             cmd->se_cmd);
         entry->rsp.scsi_status = SAM_STAT_CHECK_CONDITION;
         goto done;
     }
 
     read_len = se_cmd->data_length;
     if (se_cmd->data_direction == DMA_FROM_DEVICE &&
         (entry->hdr.uflags & TCMU_UFLAG_READ_LEN) && entry->rsp.read_len) {
         read_len_valid = true;
         if (entry->rsp.read_len < read_len)
             read_len = entry->rsp.read_len;
     }
 
     if (entry->rsp.scsi_status == SAM_STAT_CHECK_CONDITION) {
         transport_copy_sense_to_cmd(se_cmd, entry->rsp.sense_buffer);
         if (!read_len_valid )
             goto done;
         else
             se_cmd->se_cmd_flags |= SCF_TREAT_READ_AS_NORMAL;
     }
     if (se_cmd->se_cmd_flags & SCF_BIDI) {
         /* Get Data-In buffer before clean up */
         gather_data_area(udev, cmd, true, read_len);
     } else if (se_cmd->data_direction == DMA_FROM_DEVICE) {
         gather_data_area(udev, cmd, false, read_len);
     } else if (se_cmd->data_direction == DMA_TO_DEVICE) {
         /* TODO: */
     } else if (se_cmd->data_direction != DMA_NONE) {
         pr_warn("TCMU: data direction was %d!\n",
             se_cmd->data_direction);
     }
 
 done:
     se_cmd->priv = NULL;
     if (read_len_valid) {
         pr_debug("read_len = %d\n", read_len);
         target_complete_cmd_with_length(cmd->se_cmd,
                     entry->rsp.scsi_status, read_len);
     } else
         target_complete_cmd(cmd->se_cmd, entry->rsp.scsi_status);
 
 out:
     if (!keep_buf) {
         tcmu_cmd_free_data(cmd, cmd->dbi_cnt);
         tcmu_free_cmd(cmd);
     } else {
         /*
          * Keep this command after completion, since userspace still
          * needs the data buffer. Mark it with TCMU_CMD_BIT_KEEP_BUF
          * and reset potential TCMU_CMD_BIT_EXPIRED, so we don't accept
          * a second completion later.
          * Userspace can free the buffer later by writing the cmd_id
          * to new action attribute free_kept_buf.
          */
         clear_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags);
         set_bit(TCMU_CMD_BIT_KEEP_BUF, &cmd->flags);
     }
     return ret;
 }
 
 static int tcmu_run_tmr_queue(struct tcmu_dev *udev)
 {
     struct tcmu_tmr *tmr, *tmp;
     LIST_HEAD(tmrs);
 
     if (list_empty(&udev->tmr_queue))
         return 1;
 
     pr_debug("running %s's tmr queue\n", udev->name);
 
     list_splice_init(&udev->tmr_queue, &tmrs);
 
     list_for_each_entry_safe(tmr, tmp, &tmrs, queue_entry) {
         list_del_init(&tmr->queue_entry);
 
         pr_debug("removing tmr %p on dev %s from queue\n",
              tmr, udev->name);
 
         if (queue_tmr_ring(udev, tmr)) {
             pr_debug("ran out of space during tmr queue run\n");
             /*
              * tmr was requeued, so just put all tmrs back in
              * the queue
              */
             list_splice_tail(&tmrs, &udev->tmr_queue);
             return 0;
         }
     }
 
     return 1;
 }
 
 static bool tcmu_handle_completions(struct tcmu_dev *udev)
 {
     struct tcmu_mailbox *mb;
     struct tcmu_cmd *cmd;
     bool free_space = false;
 
     if (test_bit(TCMU_DEV_BIT_BROKEN, &udev->flags)) {
         pr_err("ring broken, not handling completions\n");
         return false;
     }
 
     mb = udev->mb_addr;
     tcmu_flush_dcache_range(mb, sizeof(*mb));
 
     while (udev->cmdr_last_cleaned != READ_ONCE(mb->cmd_tail)) {
 
         struct tcmu_cmd_entry *entry = udev->cmdr + udev->cmdr_last_cleaned;
         bool keep_buf;
 
         /*
          * Flush max. up to end of cmd ring since current entry might
          * be a padding that is shorter than sizeof(*entry)
          */
         size_t ring_left = head_to_end(udev->cmdr_last_cleaned,
                            udev->cmdr_size);
         tcmu_flush_dcache_range(entry, ring_left < sizeof(*entry) ?
                     ring_left : sizeof(*entry));
 
         free_space = true;
 
         if (tcmu_hdr_get_op(entry->hdr.len_op) == TCMU_OP_PAD ||
             tcmu_hdr_get_op(entry->hdr.len_op) == TCMU_OP_TMR) {
             UPDATE_HEAD(udev->cmdr_last_cleaned,
                     tcmu_hdr_get_len(entry->hdr.len_op),
                     udev->cmdr_size);
             continue;
         }
         WARN_ON(tcmu_hdr_get_op(entry->hdr.len_op) != TCMU_OP_CMD);
 
         keep_buf = !!(entry->hdr.uflags & TCMU_UFLAG_KEEP_BUF);
         if (keep_buf)
             cmd = xa_load(&udev->commands, entry->hdr.cmd_id);
         else
             cmd = xa_erase(&udev->commands, entry->hdr.cmd_id);
         if (!cmd) {
             pr_err("cmd_id %u not found, ring is broken\n",
                    entry->hdr.cmd_id);
             set_bit(TCMU_DEV_BIT_BROKEN, &udev->flags);
             return false;
         }
 
         if (!tcmu_handle_completion(cmd, entry, keep_buf))
             break;
 
         UPDATE_HEAD(udev->cmdr_last_cleaned,
                 tcmu_hdr_get_len(entry->hdr.len_op),
                 udev->cmdr_size);
     }
     if (free_space)
         free_space = tcmu_run_tmr_queue(udev);
 
     if (atomic_read(&global_page_count) > tcmu_global_max_pages &&
         xa_empty(&udev->commands) && list_empty(&udev->qfull_queue)) {
         /*
          * Allocated blocks exceeded global block limit, currently no
          * more pending or waiting commands so try to reclaim blocks.
          */
         schedule_delayed_work(&tcmu_unmap_work, 0);
     }
     if (udev->cmd_time_out)
         tcmu_set_next_deadline(&udev->inflight_queue, &udev->cmd_timer);
 
     return free_space;
 }
 
 static void tcmu_check_expired_ring_cmd(struct tcmu_cmd *cmd)
 {
     struct se_cmd *se_cmd;
 
     if (!time_after_eq(jiffies, cmd->deadline))
         return;
 
     set_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags);
     list_del_init(&cmd->queue_entry);
     se_cmd = cmd->se_cmd;
     se_cmd->priv = NULL;
     cmd->se_cmd = NULL;
 
     pr_debug("Timing out inflight cmd %u on dev %s.\n",
          cmd->cmd_id, cmd->tcmu_dev->name);
 
     target_complete_cmd(se_cmd, SAM_STAT_CHECK_CONDITION);
 }
 
 static void tcmu_check_expired_queue_cmd(struct tcmu_cmd *cmd)
 {
     struct se_cmd *se_cmd;
 
     if (!time_after_eq(jiffies, cmd->deadline))
         return;
 
     pr_debug("Timing out queued cmd %p on dev %s.\n",
           cmd, cmd->tcmu_dev->name);
 
     list_del_init(&cmd->queue_entry);
     se_cmd = cmd->se_cmd;
     tcmu_free_cmd(cmd);
 
     se_cmd->priv = NULL;
     target_complete_cmd(se_cmd, SAM_STAT_TASK_SET_FULL);
 }
 
 static void tcmu_device_timedout(struct tcmu_dev *udev)
 {
     spin_lock(&timed_out_udevs_lock);
     if (list_empty(&udev->timedout_entry))
         list_add_tail(&udev->timedout_entry, &timed_out_udevs);
     spin_unlock(&timed_out_udevs_lock);
 
     schedule_delayed_work(&tcmu_unmap_work, 0);
 }
 
 static void tcmu_cmd_timedout(struct timer_list *t)
 {
     struct tcmu_dev *udev = from_timer(udev, t, cmd_timer);
 
     pr_debug("%s cmd timeout has expired\n", udev->name);
     tcmu_device_timedout(udev);
 }
 
 static void tcmu_qfull_timedout(struct timer_list *t)
 {
     struct tcmu_dev *udev = from_timer(udev, t, qfull_timer);
 
     pr_debug("%s qfull timeout has expired\n", udev->name);
     tcmu_device_timedout(udev);
 }
 
 static int tcmu_attach_hba(struct se_hba *hba, u32 host_id)
 {
     struct tcmu_hba *tcmu_hba;
 
     tcmu_hba = kzalloc(sizeof(struct tcmu_hba), GFP_KERNEL);
     if (!tcmu_hba)
         return -ENOMEM;
 
     tcmu_hba->host_id = host_id;
     hba->hba_ptr = tcmu_hba;
 
     return 0;
 }
 
 static void tcmu_detach_hba(struct se_hba *hba)
 {
     kfree(hba->hba_ptr);
     hba->hba_ptr = NULL;
 }
 
 static struct se_device *tcmu_alloc_device(struct se_hba *hba, const char *name)
 {
     struct tcmu_dev *udev;
 
     udev = kzalloc(sizeof(struct tcmu_dev), GFP_KERNEL);
     if (!udev)
         return NULL;
     kref_init(&udev->kref);
 
     udev->name = kstrdup(name, GFP_KERNEL);
     if (!udev->name) {
         kfree(udev);
         return NULL;
     }
 
     udev->hba = hba;
     udev->cmd_time_out = TCMU_TIME_OUT;
     udev->qfull_time_out = -1;
 
     udev->data_pages_per_blk = DATA_PAGES_PER_BLK_DEF;
     udev->max_blocks = DATA_AREA_PAGES_DEF / udev->data_pages_per_blk;
     udev->cmdr_size = CMDR_SIZE_DEF;
     udev->data_area_mb = TCMU_PAGES_TO_MBS(DATA_AREA_PAGES_DEF);
 
     mutex_init(&udev->cmdr_lock);
 
     INIT_LIST_HEAD(&udev->node);
     INIT_LIST_HEAD(&udev->timedout_entry);
     INIT_LIST_HEAD(&udev->qfull_queue);
     INIT_LIST_HEAD(&udev->tmr_queue);
     INIT_LIST_HEAD(&udev->inflight_queue);
     xa_init_flags(&udev->commands, XA_FLAGS_ALLOC1);
 
     timer_setup(&udev->qfull_timer, tcmu_qfull_timedout, 0);
     timer_setup(&udev->cmd_timer, tcmu_cmd_timedout, 0);
 
     xa_init(&udev->data_pages);
 
     return &udev->se_dev;
 }
 
 static void tcmu_dev_call_rcu(struct rcu_head *p)
 {
     struct se_device *dev = container_of(p, struct se_device, rcu_head);
     struct tcmu_dev *udev = TCMU_DEV(dev);
 
     kfree(udev->uio_info.name);
     kfree(udev->name);
     kfree(udev);
 }
 
 static int tcmu_check_and_free_pending_cmd(struct tcmu_cmd *cmd)
 {
     if (test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags) ||
         test_bit(TCMU_CMD_BIT_KEEP_BUF, &cmd->flags)) {
         kmem_cache_free(tcmu_cmd_cache, cmd);
         return 0;
     }
     return -EINVAL;
 }
 
 static u32 tcmu_blocks_release(struct tcmu_dev *udev, unsigned long first,
                 unsigned long last)
 {
     struct page *page;
     unsigned long dpi;
     u32 pages_freed = 0;
 
     first = first * udev->data_pages_per_blk;
     last = (last + 1) * udev->data_pages_per_blk - 1;
     xa_for_each_range(&udev->data_pages, dpi, page, first, last) {
         xa_erase(&udev->data_pages, dpi);
         /*
          * While reaching here there may be page faults occurring on
          * the to-be-released pages. A race condition may occur if
          * unmap_mapping_range() is called before page faults on these
          * pages have completed; a valid but stale map is created.
          *
          * If another command subsequently runs and needs to extend
          * dbi_thresh, it may reuse the slot corresponding to the
          * previous page in data_bitmap. Though we will allocate a new
          * page for the slot in data_area, no page fault will happen
          * because we have a valid map. Therefore the command's data
          * will be lost.
          *
          * We lock and unlock pages that are to be released to ensure
          * all page faults have completed. This way
          * unmap_mapping_range() can ensure stale maps are cleanly
          * removed.
          */
         lock_page(page);
         unlock_page(page);
         __free_page(page);
         pages_freed++;
     }
 
     atomic_sub(pages_freed, &global_page_count);
 
     return pages_freed;
 }
 
 static void tcmu_remove_all_queued_tmr(struct tcmu_dev *udev)
 {
     struct tcmu_tmr *tmr, *tmp;
 
     list_for_each_entry_safe(tmr, tmp, &udev->tmr_queue, queue_entry) {
         list_del_init(&tmr->queue_entry);
         kfree(tmr);
     }
 }
 
 static void tcmu_dev_kref_release(struct kref *kref)
 {
     struct tcmu_dev *udev = container_of(kref, struct tcmu_dev, kref);
     struct se_device *dev = &udev->se_dev;
     struct tcmu_cmd *cmd;
     bool all_expired = true;
     unsigned long i;
 
     vfree(udev->mb_addr);
     udev->mb_addr = NULL;
 
     spin_lock_bh(&timed_out_udevs_lock);
     if (!list_empty(&udev->timedout_entry))
         list_del(&udev->timedout_entry);
     spin_unlock_bh(&timed_out_udevs_lock);
 
     /* Upper layer should drain all requests before calling this */
     mutex_lock(&udev->cmdr_lock);
     xa_for_each(&udev->commands, i, cmd) {
         if (tcmu_check_and_free_pending_cmd(cmd) != 0)
             all_expired = false;
     }
     /* There can be left over TMR cmds. Remove them. */
     tcmu_remove_all_queued_tmr(udev);
     if (!list_empty(&udev->qfull_queue))
         all_expired = false;
     xa_destroy(&udev->commands);
     WARN_ON(!all_expired);
 
     tcmu_blocks_release(udev, 0, udev->dbi_max);
     bitmap_free(udev->data_bitmap);
     mutex_unlock(&udev->cmdr_lock);
 
     pr_debug("dev_kref_release\n");
 
     call_rcu(&dev->rcu_head, tcmu_dev_call_rcu);
 }
 
 static void run_qfull_queue(struct tcmu_dev *udev, bool fail)
 {
     struct tcmu_cmd *tcmu_cmd, *tmp_cmd;
     LIST_HEAD(cmds);
     sense_reason_t scsi_ret;
     int ret;
 
     if (list_empty(&udev->qfull_queue))
         return;
 
     pr_debug("running %s's cmdr queue forcefail %d\n", udev->name, fail);
 
     list_splice_init(&udev->qfull_queue, &cmds);
 
     list_for_each_entry_safe(tcmu_cmd, tmp_cmd, &cmds, queue_entry) {
         list_del_init(&tcmu_cmd->queue_entry);
 
         pr_debug("removing cmd %p on dev %s from queue\n",
              tcmu_cmd, udev->name);
 
         if (fail) {
             /*
              * We were not able to even start the command, so
              * fail with busy to allow a retry in case runner
              * was only temporarily down. If the device is being
              * removed then LIO core will do the right thing and
              * fail the retry.
              */
             tcmu_cmd->se_cmd->priv = NULL;
             target_complete_cmd(tcmu_cmd->se_cmd, SAM_STAT_BUSY);
             tcmu_free_cmd(tcmu_cmd);
             continue;
         }
 
         ret = queue_cmd_ring(tcmu_cmd, &scsi_ret);
         if (ret < 0) {
             pr_debug("cmd %p on dev %s failed with %u\n",
                  tcmu_cmd, udev->name, scsi_ret);
             /*
              * Ignore scsi_ret for now. target_complete_cmd
              * drops it.
              */
             tcmu_cmd->se_cmd->priv = NULL;
             target_complete_cmd(tcmu_cmd->se_cmd,
                         SAM_STAT_CHECK_CONDITION);
             tcmu_free_cmd(tcmu_cmd);
         } else if (ret > 0) {
             pr_debug("ran out of space during cmdr queue run\n");
             /*
              * cmd was requeued, so just put all cmds back in
              * the queue
              */
             list_splice_tail(&cmds, &udev->qfull_queue);
             break;
         }
     }
 
     tcmu_set_next_deadline(&udev->qfull_queue, &udev->qfull_timer);
 }
 
 static int tcmu_irqcontrol(struct uio_info *info, s32 irq_on)
 {
     struct tcmu_dev *udev = container_of(info, struct tcmu_dev, uio_info);
 
     mutex_lock(&udev->cmdr_lock);
     if (tcmu_handle_completions(udev))
         run_qfull_queue(udev, false);
     mutex_unlock(&udev->cmdr_lock);
 
     return 0;
 }
 
 /*
  * mmap code from uio.c. Copied here because we want to hook mmap()
  * and this stuff must come along.
  */
 static int tcmu_find_mem_index(struct vm_area_struct *vma)
 {
     struct tcmu_dev *udev = vma->vm_private_data;
     struct uio_info *info = &udev->uio_info;
 
     if (vma->vm_pgoff < MAX_UIO_MAPS) {
         if (info->mem[vma->vm_pgoff].size == 0)
             return -1;
         return (int)vma->vm_pgoff;
     }
     return -1;
 }
 
 static struct page *tcmu_try_get_data_page(struct tcmu_dev *udev, uint32_t dpi)
 {
     struct page *page;
 
     mutex_lock(&udev->cmdr_lock);
     page = xa_load(&udev->data_pages, dpi);
     if (likely(page)) {
         get_page(page);
         lock_page(page);
         mutex_unlock(&udev->cmdr_lock);
         return page;
     }
 
     /*
      * Userspace messed up and passed in a address not in the
      * data iov passed to it.
      */
     pr_err("Invalid addr to data page mapping (dpi %u) on device %s\n",
            dpi, udev->name);
     mutex_unlock(&udev->cmdr_lock);
 
     return NULL;
 }
 
 static void tcmu_vma_open(struct vm_area_struct *vma)
 {
     struct tcmu_dev *udev = vma->vm_private_data;
 
     pr_debug("vma_open\n");
 
     kref_get(&udev->kref);
 }
 
 static void tcmu_vma_close(struct vm_area_struct *vma)
 {
     struct tcmu_dev *udev = vma->vm_private_data;
 
     pr_debug("vma_close\n");
 
     /* release ref from tcmu_vma_open */
     kref_put(&udev->kref, tcmu_dev_kref_release);
 }
 
 static vm_fault_t tcmu_vma_fault(struct vm_fault *vmf)
 {
     struct tcmu_dev *udev = vmf->vma->vm_private_data;
     struct uio_info *info = &udev->uio_info;
     struct page *page;
     unsigned long offset;
     void *addr;
     vm_fault_t ret = 0;
 
     int mi = tcmu_find_mem_index(vmf->vma);
     if (mi < 0)
         return VM_FAULT_SIGBUS;
 
     /*
      * We need to subtract mi because userspace uses offset = N*PAGE_SIZE
      * to use mem[N].
      */
     offset = (vmf->pgoff - mi) << PAGE_SHIFT;
 
     if (offset < udev->data_off) {
         /* For the vmalloc()ed cmd area pages */
         addr = (void *)(unsigned long)info->mem[mi].addr + offset;
         page = vmalloc_to_page(addr);
         get_page(page);
     } else {
         uint32_t dpi;
 
         /* For the dynamically growing data area pages */
         dpi = (offset - udev->data_off) / PAGE_SIZE;
         page = tcmu_try_get_data_page(udev, dpi);
         if (!page)
             return VM_FAULT_SIGBUS;
         ret = VM_FAULT_LOCKED;
     }
 
     vmf->page = page;
     return ret;
 }
 
 static const struct vm_operations_struct tcmu_vm_ops = {
     .open = tcmu_vma_open,
     .close = tcmu_vma_close,
     .fault = tcmu_vma_fault,
 };
 
 static int tcmu_mmap(struct uio_info *info, struct vm_area_struct *vma)
 {
     struct tcmu_dev *udev = container_of(info, struct tcmu_dev, uio_info);
 
     vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
     vma->vm_ops = &tcmu_vm_ops;
 
     vma->vm_private_data = udev;
 
     /* Ensure the mmap is exactly the right size */
     if (vma_pages(vma) != udev->mmap_pages)
         return -EINVAL;
 
     tcmu_vma_open(vma);
 
     return 0;
 }
 
 static int tcmu_open(struct uio_info *info, struct inode *inode)
 {
     struct tcmu_dev *udev = container_of(info, struct tcmu_dev, uio_info);
 
     /* O_EXCL not supported for char devs, so fake it? */
     if (test_and_set_bit(TCMU_DEV_BIT_OPEN, &udev->flags))
         return -EBUSY;
 
     udev->inode = inode;
 
     pr_debug("open\n");
 
     return 0;
 }
 
 static int tcmu_release(struct uio_info *info, struct inode *inode)
 {
     struct tcmu_dev *udev = container_of(info, struct tcmu_dev, uio_info);
     struct tcmu_cmd *cmd;
     unsigned long i;
     bool freed = false;
 
     mutex_lock(&udev->cmdr_lock);
 
     xa_for_each(&udev->commands, i, cmd) {
         /* Cmds with KEEP_BUF set are no longer on the ring, but
          * userspace still holds the data buffer. If userspace closes
          * we implicitly free these cmds and buffers, since after new
          * open the (new ?) userspace cannot find the cmd in the ring
          * and thus never will release the buffer by writing cmd_id to
          * free_kept_buf action attribute.
          */
         if (!test_bit(TCMU_CMD_BIT_KEEP_BUF, &cmd->flags))
             continue;
         pr_debug("removing KEEP_BUF cmd %u on dev %s from ring\n",
              cmd->cmd_id, udev->name);
         freed = true;
 
         xa_erase(&udev->commands, i);
         tcmu_cmd_free_data(cmd, cmd->dbi_cnt);
         tcmu_free_cmd(cmd);
     }
     /*
      * We only freed data space, not ring space. Therefore we dont call
      * run_tmr_queue, but call run_qfull_queue if tmr_list is empty.
      */
     if (freed && list_empty(&udev->tmr_queue))
         run_qfull_queue(udev, false);
 
     mutex_unlock(&udev->cmdr_lock);
 
     clear_bit(TCMU_DEV_BIT_OPEN, &udev->flags);
 
     pr_debug("close\n");
 
     return 0;
 }
 
 static int tcmu_init_genl_cmd_reply(struct tcmu_dev *udev, int cmd)
 {
     struct tcmu_nl_cmd *nl_cmd = &udev->curr_nl_cmd;
 
     if (!tcmu_kern_cmd_reply_supported)
         return 0;
 
     if (udev->nl_reply_supported <= 0)
         return 0;
 
     mutex_lock(&tcmu_nl_cmd_mutex);
 
     if (tcmu_netlink_blocked) {
         mutex_unlock(&tcmu_nl_cmd_mutex);
         pr_warn("Failing nl cmd %d on %s. Interface is blocked.\n", cmd,
             udev->name);
         return -EAGAIN;
     }
 
     if (nl_cmd->cmd != TCMU_CMD_UNSPEC) {
         mutex_unlock(&tcmu_nl_cmd_mutex);
         pr_warn("netlink cmd %d already executing on %s\n",
              nl_cmd->cmd, udev->name);
         return -EBUSY;
     }
 
     memset(nl_cmd, 0, sizeof(*nl_cmd));
     nl_cmd->cmd = cmd;
     nl_cmd->udev = udev;
     init_completion(&nl_cmd->complete);
     INIT_LIST_HEAD(&nl_cmd->nl_list);
 
     list_add_tail(&nl_cmd->nl_list, &tcmu_nl_cmd_list);
 
     mutex_unlock(&tcmu_nl_cmd_mutex);
     return 0;
 }
 
 static void tcmu_destroy_genl_cmd_reply(struct tcmu_dev *udev)
 {
     struct tcmu_nl_cmd *nl_cmd = &udev->curr_nl_cmd;
 
     if (!tcmu_kern_cmd_reply_supported)
         return;
 
     if (udev->nl_reply_supported <= 0)
         return;
 
     mutex_lock(&tcmu_nl_cmd_mutex);
 
     list_del(&nl_cmd->nl_list);
     memset(nl_cmd, 0, sizeof(*nl_cmd));
 
     mutex_unlock(&tcmu_nl_cmd_mutex);
 }
 
 static int tcmu_wait_genl_cmd_reply(struct tcmu_dev *udev)
 {
     struct tcmu_nl_cmd *nl_cmd = &udev->curr_nl_cmd;
     int ret;
 
     if (!tcmu_kern_cmd_reply_supported)
         return 0;
 
     if (udev->nl_reply_supported <= 0)
         return 0;
 
     pr_debug("sleeping for nl reply\n");
     wait_for_completion(&nl_cmd->complete);
 
     mutex_lock(&tcmu_nl_cmd_mutex);
     nl_cmd->cmd = TCMU_CMD_UNSPEC;
     ret = nl_cmd->status;
     mutex_unlock(&tcmu_nl_cmd_mutex);
 
     return ret;
 }
 
 static int tcmu_netlink_event_init(struct tcmu_dev *udev,
                    enum tcmu_genl_cmd cmd,
                    struct sk_buff **buf, void **hdr)
 {
     struct sk_buff *skb;
     void *msg_header;
     int ret = -ENOMEM;
 
     skb = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
     if (!skb)
         return ret;
 
     msg_header = genlmsg_put(skb, 0, 0, &tcmu_genl_family, 0, cmd);
     if (!msg_header)
         goto free_skb;
 
     ret = nla_put_string(skb, TCMU_ATTR_DEVICE, udev->uio_info.name);
     if (ret < 0)
         goto free_skb;
 
     ret = nla_put_u32(skb, TCMU_ATTR_MINOR, udev->uio_info.uio_dev->minor);
     if (ret < 0)
         goto free_skb;
 
     ret = nla_put_u32(skb, TCMU_ATTR_DEVICE_ID, udev->se_dev.dev_index);
     if (ret < 0)
         goto free_skb;
 
     *buf = skb;
     *hdr = msg_header;
     return ret;
 
 free_skb:
     nlmsg_free(skb);
     return ret;
 }
 
 static int tcmu_netlink_event_send(struct tcmu_dev *udev,
                    enum tcmu_genl_cmd cmd,
                    struct sk_buff *skb, void *msg_header)
 {
     int ret;
 
     genlmsg_end(skb, msg_header);
 
     ret = tcmu_init_genl_cmd_reply(udev, cmd);
     if (ret) {
         nlmsg_free(skb);
         return ret;
     }
 
     ret = genlmsg_multicast_allns(&tcmu_genl_family, skb, 0,
                       TCMU_MCGRP_CONFIG, GFP_KERNEL);
 
     /* Wait during an add as the listener may not be up yet */
     if (ret == 0 ||
        (ret == -ESRCH && cmd == TCMU_CMD_ADDED_DEVICE))
         return tcmu_wait_genl_cmd_reply(udev);
     else
         tcmu_destroy_genl_cmd_reply(udev);
 
     return ret;
 }
 
 static int tcmu_send_dev_add_event(struct tcmu_dev *udev)
 {
     struct sk_buff *skb = NULL;
     void *msg_header = NULL;
     int ret = 0;
 
     ret = tcmu_netlink_event_init(udev, TCMU_CMD_ADDED_DEVICE, &skb,
                       &msg_header);
     if (ret < 0)
         return ret;
     return tcmu_netlink_event_send(udev, TCMU_CMD_ADDED_DEVICE, skb,
                        msg_header);
 }
 
 static int tcmu_send_dev_remove_event(struct tcmu_dev *udev)
 {
     struct sk_buff *skb = NULL;
     void *msg_header = NULL;
     int ret = 0;
 
     ret = tcmu_netlink_event_init(udev, TCMU_CMD_REMOVED_DEVICE,
                       &skb, &msg_header);
     if (ret < 0)
         return ret;
     return tcmu_netlink_event_send(udev, TCMU_CMD_REMOVED_DEVICE,
                        skb, msg_header);
 }
 
 static int tcmu_update_uio_info(struct tcmu_dev *udev)
 {
     struct tcmu_hba *hba = udev->hba->hba_ptr;
     struct uio_info *info;
     char *str;
 
     info = &udev->uio_info;
 
     if (udev->dev_config[0])
         str = kasprintf(GFP_KERNEL, "tcm-user/%u/%s/%s", hba->host_id,
                 udev->name, udev->dev_config);
     else
         str = kasprintf(GFP_KERNEL, "tcm-user/%u/%s", hba->host_id,
                 udev->name);
     if (!str)
         return -ENOMEM;
 
     /* If the old string exists, free it */
     kfree(info->name);
     info->name = str;
 
     return 0;
 }
 
 static int tcmu_configure_device(struct se_device *dev)
 {
     struct tcmu_dev *udev = TCMU_DEV(dev);
     struct uio_info *info;
     struct tcmu_mailbox *mb;
     size_t data_size;
     int ret = 0;
 
     ret = tcmu_update_uio_info(udev);
     if (ret)
         return ret;
 
     info = &udev->uio_info;
 
     mutex_lock(&udev->cmdr_lock);
     udev->data_bitmap = bitmap_zalloc(udev->max_blocks, GFP_KERNEL);
     mutex_unlock(&udev->cmdr_lock);
     if (!udev->data_bitmap) {
         ret = -ENOMEM;
         goto err_bitmap_alloc;
     }
 
     mb = vzalloc(udev->cmdr_size + CMDR_OFF);
     if (!mb) {
         ret = -ENOMEM;
         goto err_vzalloc;
     }
 
     /* mailbox fits in first part of CMDR space */
     udev->mb_addr = mb;
     udev->cmdr = (void *)mb + CMDR_OFF;
     udev->data_off = udev->cmdr_size + CMDR_OFF;
     data_size = TCMU_MBS_TO_PAGES(udev->data_area_mb) << PAGE_SHIFT;
     udev->mmap_pages = (data_size + udev->cmdr_size + CMDR_OFF) >> PAGE_SHIFT;
     udev->data_blk_size = udev->data_pages_per_blk * PAGE_SIZE;
     udev->dbi_thresh = 0; /* Default in Idle state */
 
     /* Initialise the mailbox of the ring buffer */
     mb->version = TCMU_MAILBOX_VERSION;
     mb->flags = TCMU_MAILBOX_FLAG_CAP_OOOC |
             TCMU_MAILBOX_FLAG_CAP_READ_LEN |
             TCMU_MAILBOX_FLAG_CAP_TMR |
             TCMU_MAILBOX_FLAG_CAP_KEEP_BUF;
     mb->cmdr_off = CMDR_OFF;
     mb->cmdr_size = udev->cmdr_size;
 
     WARN_ON(!PAGE_ALIGNED(udev->data_off));
     WARN_ON(data_size % PAGE_SIZE);
 
     info->version = __stringify(TCMU_MAILBOX_VERSION);
 
     info->mem[0].name = "tcm-user command & data buffer";
     info->mem[0].addr = (phys_addr_t)(uintptr_t)udev->mb_addr;
     info->mem[0].size = data_size + udev->cmdr_size + CMDR_OFF;
     info->mem[0].memtype = UIO_MEM_NONE;
 
     info->irqcontrol = tcmu_irqcontrol;
     info->irq = UIO_IRQ_CUSTOM;
 
     info->mmap = tcmu_mmap;
     info->open = tcmu_open;
     info->release = tcmu_release;
 
     ret = uio_register_device(tcmu_root_device, info);
     if (ret)
         goto err_register;
 
     /* User can set hw_block_size before enable the device */
     if (dev->dev_attrib.hw_block_size == 0)
         dev->dev_attrib.hw_block_size = 512;
     /* Other attributes can be configured in userspace */
     if (!dev->dev_attrib.hw_max_sectors)
         dev->dev_attrib.hw_max_sectors = 128;
     if (!dev->dev_attrib.emulate_write_cache)
         dev->dev_attrib.emulate_write_cache = 0;
     dev->dev_attrib.hw_queue_depth = 128;
 
     /* If user didn't explicitly disable netlink reply support, use
      * module scope setting.
      */
     if (udev->nl_reply_supported >= 0)
         udev->nl_reply_supported = tcmu_kern_cmd_reply_supported;
 
     /*
      * Get a ref incase userspace does a close on the uio device before
      * LIO has initiated tcmu_free_device.
      */
     kref_get(&udev->kref);
 
     ret = tcmu_send_dev_add_event(udev);
     if (ret)
         goto err_netlink;
 
     mutex_lock(&root_udev_mutex);
     list_add(&udev->node, &root_udev);
     mutex_unlock(&root_udev_mutex);
 
     return 0;
 
 err_netlink:
     kref_put(&udev->kref, tcmu_dev_kref_release);
     uio_unregister_device(&udev->uio_info);
 err_register:
     vfree(udev->mb_addr);
     udev->mb_addr = NULL;
 err_vzalloc:
     bitmap_free(udev->data_bitmap);
     udev->data_bitmap = NULL;
 err_bitmap_alloc:
     kfree(info->name);
     info->name = NULL;
 
     return ret;
 }
 
 static void tcmu_free_device(struct se_device *dev)
 {
     struct tcmu_dev *udev = TCMU_DEV(dev);
 
     /* release ref from init */
     kref_put(&udev->kref, tcmu_dev_kref_release);
 }
 
 static void tcmu_destroy_device(struct se_device *dev)
 {
     struct tcmu_dev *udev = TCMU_DEV(dev);
 
     del_timer_sync(&udev->cmd_timer);
     del_timer_sync(&udev->qfull_timer);
 
     mutex_lock(&root_udev_mutex);
     list_del(&udev->node);
     mutex_unlock(&root_udev_mutex);
 
     tcmu_send_dev_remove_event(udev);
 
     uio_unregister_device(&udev->uio_info);
 
     /* release ref from configure */
     kref_put(&udev->kref, tcmu_dev_kref_release);
 }
 
 static void tcmu_unblock_dev(struct tcmu_dev *udev)
 {
     mutex_lock(&udev->cmdr_lock);
     clear_bit(TCMU_DEV_BIT_BLOCKED, &udev->flags);
     mutex_unlock(&udev->cmdr_lock);
 }
 
 static void tcmu_block_dev(struct tcmu_dev *udev)
 {
     mutex_lock(&udev->cmdr_lock);
 
     if (test_and_set_bit(TCMU_DEV_BIT_BLOCKED, &udev->flags))
         goto unlock;
 
     /* complete IO that has executed successfully */
     tcmu_handle_completions(udev);
     /* fail IO waiting to be queued */
     run_qfull_queue(udev, true);
 
 unlock:
     mutex_unlock(&udev->cmdr_lock);
 }
 
 static void tcmu_reset_ring(struct tcmu_dev *udev, u8 err_level)
 {
     struct tcmu_mailbox *mb;
     struct tcmu_cmd *cmd;
     unsigned long i;
 
     mutex_lock(&udev->cmdr_lock);
 
     xa_for_each(&udev->commands, i, cmd) {
         pr_debug("removing cmd %u on dev %s from ring %s\n",
              cmd->cmd_id, udev->name,
              test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags) ?
              "(is expired)" :
              (test_bit(TCMU_CMD_BIT_KEEP_BUF, &cmd->flags) ?
              "(is keep buffer)" : ""));
 
         xa_erase(&udev->commands, i);
         if (!test_bit(TCMU_CMD_BIT_EXPIRED, &cmd->flags) &&
             !test_bit(TCMU_CMD_BIT_KEEP_BUF, &cmd->flags)) {
             WARN_ON(!cmd->se_cmd);
             list_del_init(&cmd->queue_entry);
             cmd->se_cmd->priv = NULL;
             if (err_level == 1) {
                 /*
                  * Userspace was not able to start the
                  * command or it is retryable.
                  */
                 target_complete_cmd(cmd->se_cmd, SAM_STAT_BUSY);
             } else {
                 /* hard failure */
                 target_complete_cmd(cmd->se_cmd,
                             SAM_STAT_CHECK_CONDITION);
             }
         }
         tcmu_cmd_free_data(cmd, cmd->dbi_cnt);
         tcmu_free_cmd(cmd);
     }
 
     mb = udev->mb_addr;
     tcmu_flush_dcache_range(mb, sizeof(*mb));
     pr_debug("mb last %u head %u tail %u\n", udev->cmdr_last_cleaned,
          mb->cmd_tail, mb->cmd_head);
 
     udev->cmdr_last_cleaned = 0;
     mb->cmd_tail = 0;
     mb->cmd_head = 0;
     tcmu_flush_dcache_range(mb, sizeof(*mb));
     clear_bit(TCMU_DEV_BIT_BROKEN, &udev->flags);
 
     del_timer(&udev->cmd_timer);
 
     /*
      * ring is empty and qfull queue never contains aborted commands.
      * So TMRs in tmr queue do not contain relevant cmd_ids.
      * After a ring reset userspace should do a fresh start, so
      * even LUN RESET message is no longer relevant.
      * Therefore remove all TMRs from qfull queue
      */
     tcmu_remove_all_queued_tmr(udev);
 
     run_qfull_queue(udev, false);
 
     mutex_unlock(&udev->cmdr_lock);
 }
 
 enum {
     Opt_dev_config, Opt_dev_size, Opt_hw_block_size, Opt_hw_max_sectors,
     Opt_nl_reply_supported, Opt_max_data_area_mb, Opt_data_pages_per_blk,
     Opt_cmd_ring_size_mb, Opt_err,
 };
 
 static match_table_t tokens = {
     {Opt_dev_config, "dev_config=%s"},
     {Opt_dev_size, "dev_size=%s"},
     {Opt_hw_block_size, "hw_block_size=%d"},
     {Opt_hw_max_sectors, "hw_max_sectors=%d"},
     {Opt_nl_reply_supported, "nl_reply_supported=%d"},
     {Opt_max_data_area_mb, "max_data_area_mb=%d"},
     {Opt_data_pages_per_blk, "data_pages_per_blk=%d"},
     {Opt_cmd_ring_size_mb, "cmd_ring_size_mb=%d"},
     {Opt_err, NULL}
 };
 
 static int tcmu_set_dev_attrib(substring_t *arg, u32 *dev_attrib)
 {
     int val, ret;
 
     ret = match_int(arg, &val);
     if (ret < 0) {
         pr_err("match_int() failed for dev attrib. Error %d.\n",
                ret);
         return ret;
     }
 
     if (val <= 0) {
         pr_err("Invalid dev attrib value %d. Must be greater than zero.\n",
                val);
         return -EINVAL;
     }
     *dev_attrib = val;
     return 0;
 }
 
 static int tcmu_set_max_blocks_param(struct tcmu_dev *udev, substring_t *arg)
 {
     int val, ret;
     uint32_t pages_per_blk = udev->data_pages_per_blk;
 
     ret = match_int(arg, &val);
     if (ret < 0) {
         pr_err("match_int() failed for max_data_area_mb=. Error %d.\n",
                ret);
         return ret;
     }
     if (val <= 0) {
         pr_err("Invalid max_data_area %d.\n", val);
         return -EINVAL;
     }
     if (val > TCMU_PAGES_TO_MBS(tcmu_global_max_pages)) {
         pr_err("%d is too large. Adjusting max_data_area_mb to global limit of %u\n",
                val, TCMU_PAGES_TO_MBS(tcmu_global_max_pages));
         val = TCMU_PAGES_TO_MBS(tcmu_global_max_pages);
     }
     if (TCMU_MBS_TO_PAGES(val) < pages_per_blk) {
         pr_err("Invalid max_data_area %d (%zu pages): smaller than data_pages_per_blk (%u pages).\n",
                val, TCMU_MBS_TO_PAGES(val), pages_per_blk);
         return -EINVAL;
     }
 
     mutex_lock(&udev->cmdr_lock);
     if (udev->data_bitmap) {
         pr_err("Cannot set max_data_area_mb after it has been enabled.\n");
         ret = -EINVAL;
         goto unlock;
     }
 
     udev->data_area_mb = val;
     udev->max_blocks = TCMU_MBS_TO_PAGES(val) / pages_per_blk;
 
 unlock:
     mutex_unlock(&udev->cmdr_lock);
     return ret;
 }
 
 static int tcmu_set_data_pages_per_blk(struct tcmu_dev *udev, substring_t *arg)
 {
     int val, ret;
 
     ret = match_int(arg, &val);
     if (ret < 0) {
         pr_err("match_int() failed for data_pages_per_blk=. Error %d.\n",
                ret);
         return ret;
     }
 
     if (val > TCMU_MBS_TO_PAGES(udev->data_area_mb)) {
         pr_err("Invalid data_pages_per_blk %d: greater than max_data_area_mb %d -> %zd pages).\n",
                val, udev->data_area_mb,
                TCMU_MBS_TO_PAGES(udev->data_area_mb));
         return -EINVAL;
     }
 
     mutex_lock(&udev->cmdr_lock);
     if (udev->data_bitmap) {
         pr_err("Cannot set data_pages_per_blk after it has been enabled.\n");
         ret = -EINVAL;
         goto unlock;
     }
 
     udev->data_pages_per_blk = val;
     udev->max_blocks = TCMU_MBS_TO_PAGES(udev->data_area_mb) / val;
 
 unlock:
     mutex_unlock(&udev->cmdr_lock);
     return ret;
 }
 
 static int tcmu_set_cmd_ring_size(struct tcmu_dev *udev, substring_t *arg)
 {
     int val, ret;
 
     ret = match_int(arg, &val);
     if (ret < 0) {
         pr_err("match_int() failed for cmd_ring_size_mb=. Error %d.\n",
                ret);
         return ret;
     }
 
     if (val <= 0) {
         pr_err("Invalid cmd_ring_size_mb %d.\n", val);
         return -EINVAL;
     }
 
     mutex_lock(&udev->cmdr_lock);
     if (udev->data_bitmap) {
         pr_err("Cannot set cmd_ring_size_mb after it has been enabled.\n");
         ret = -EINVAL;
         goto unlock;
     }
 
     udev->cmdr_size = (val << 20) - CMDR_OFF;
     if (val > (MB_CMDR_SIZE_DEF >> 20)) {
         pr_err("%d is too large. Adjusting cmd_ring_size_mb to global limit of %u\n",
                val, (MB_CMDR_SIZE_DEF >> 20));
         udev->cmdr_size = CMDR_SIZE_DEF;
     }
 
 unlock:
     mutex_unlock(&udev->cmdr_lock);
     return ret;
 }
 
 static ssize_t tcmu_set_configfs_dev_params(struct se_device *dev,
         const char *page, ssize_t count)
 {
     struct tcmu_dev *udev = TCMU_DEV(dev);
     char *orig, *ptr, *opts;
     substring_t args[MAX_OPT_ARGS];
     int ret = 0, token;
 
     opts = kstrdup(page, GFP_KERNEL);
     if (!opts)
         return -ENOMEM;
 
     orig = opts;
 
     while ((ptr = strsep(&opts, ",\n")) != NULL) {
         if (!*ptr)
             continue;
 
         token = match_token(ptr, tokens, args);
         switch (token) {
         case Opt_dev_config:
             if (match_strlcpy(udev->dev_config, &args[0],
                       TCMU_CONFIG_LEN) == 0) {
                 ret = -EINVAL;
                 break;
             }
             pr_debug("TCMU: Referencing Path: %s\n", udev->dev_config);
             break;
         case Opt_dev_size:
             ret = match_u64(&args[0], &udev->dev_size);
             if (ret < 0)
                 pr_err("match_u64() failed for dev_size=. Error %d.\n",
                        ret);
             break;
         case Opt_hw_block_size:
             ret = tcmu_set_dev_attrib(&args[0],
                     &(dev->dev_attrib.hw_block_size));
             break;
         case Opt_hw_max_sectors:
             ret = tcmu_set_dev_attrib(&args[0],
                     &(dev->dev_attrib.hw_max_sectors));
             break;
         case Opt_nl_reply_supported:
             ret = match_int(&args[0], &udev->nl_reply_supported);
             if (ret < 0)
                 pr_err("match_int() failed for nl_reply_supported=. Error %d.\n",
                        ret);
             break;
         case Opt_max_data_area_mb:
             ret = tcmu_set_max_blocks_param(udev, &args[0]);
             break;
         case Opt_data_pages_per_blk:
             ret = tcmu_set_data_pages_per_blk(udev, &args[0]);
             break;
         case Opt_cmd_ring_size_mb:
             ret = tcmu_set_cmd_ring_size(udev, &args[0]);
             break;
         default:
             break;
         }
 
         if (ret)
             break;
     }
 
     kfree(orig);
     return (!ret) ? count : ret;
 }
 
 static ssize_t tcmu_show_configfs_dev_params(struct se_device *dev, char *b)
 {
     struct tcmu_dev *udev = TCMU_DEV(dev);
     ssize_t bl = 0;
 
     bl = sprintf(b + bl, "Config: %s ",
              udev->dev_config[0] ? udev->dev_config : "NULL");
     bl += sprintf(b + bl, "Size: %llu ", udev->dev_size);
     bl += sprintf(b + bl, "MaxDataAreaMB: %u ", udev->data_area_mb);
     bl += sprintf(b + bl, "DataPagesPerBlk: %u ", udev->data_pages_per_blk);
     bl += sprintf(b + bl, "CmdRingSizeMB: %u\n",
               (udev->cmdr_size + CMDR_OFF) >> 20);
 
     return bl;
 }
 
 static sector_t tcmu_get_blocks(struct se_device *dev)
 {
     struct tcmu_dev *udev = TCMU_DEV(dev);
 
     return div_u64(udev->dev_size - dev->dev_attrib.block_size,
                dev->dev_attrib.block_size);
 }
 
 static sense_reason_t
 tcmu_parse_cdb(struct se_cmd *cmd)
 {
     return passthrough_parse_cdb(cmd, tcmu_queue_cmd);
 }
 
 static ssize_t tcmu_cmd_time_out_show(struct config_item *item, char *page)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                     struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
 
     return snprintf(page, PAGE_SIZE, "%lu\n", udev->cmd_time_out / MSEC_PER_SEC);
 }
 
 static ssize_t tcmu_cmd_time_out_store(struct config_item *item, const char *page,
                        size_t count)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                     struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = container_of(da->da_dev,
                     struct tcmu_dev, se_dev);
     u32 val;
     int ret;
 
     if (da->da_dev->export_count) {
         pr_err("Unable to set tcmu cmd_time_out while exports exist\n");
         return -EINVAL;
     }
 
     ret = kstrtou32(page, 0, &val);
     if (ret < 0)
         return ret;
 
     udev->cmd_time_out = val * MSEC_PER_SEC;
     return count;
 }
 CONFIGFS_ATTR(tcmu_, cmd_time_out);
 
 static ssize_t tcmu_qfull_time_out_show(struct config_item *item, char *page)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                         struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
 
     return snprintf(page, PAGE_SIZE, "%ld\n", udev->qfull_time_out <= 0 ?
             udev->qfull_time_out :
             udev->qfull_time_out / MSEC_PER_SEC);
 }
 
 static ssize_t tcmu_qfull_time_out_store(struct config_item *item,
                      const char *page, size_t count)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                     struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
     s32 val;
     int ret;
 
     ret = kstrtos32(page, 0, &val);
     if (ret < 0)
         return ret;
 
     if (val >= 0) {
         udev->qfull_time_out = val * MSEC_PER_SEC;
     } else if (val == -1) {
         udev->qfull_time_out = val;
     } else {
         printk(KERN_ERR "Invalid qfull timeout value %d\n", val);
         return -EINVAL;
     }
     return count;
 }
 CONFIGFS_ATTR(tcmu_, qfull_time_out);
 
 static ssize_t tcmu_max_data_area_mb_show(struct config_item *item, char *page)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                         struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
 
     return snprintf(page, PAGE_SIZE, "%u\n", udev->data_area_mb);
 }
 CONFIGFS_ATTR_RO(tcmu_, max_data_area_mb);
 
 static ssize_t tcmu_data_pages_per_blk_show(struct config_item *item,
                         char *page)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                         struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
 
     return snprintf(page, PAGE_SIZE, "%u\n", udev->data_pages_per_blk);
 }
 CONFIGFS_ATTR_RO(tcmu_, data_pages_per_blk);
 
 static ssize_t tcmu_cmd_ring_size_mb_show(struct config_item *item, char *page)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                         struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
 
     return snprintf(page, PAGE_SIZE, "%u\n",
             (udev->cmdr_size + CMDR_OFF) >> 20);
 }
 CONFIGFS_ATTR_RO(tcmu_, cmd_ring_size_mb);
 
 static ssize_t tcmu_dev_config_show(struct config_item *item, char *page)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                         struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
 
     return snprintf(page, PAGE_SIZE, "%s\n", udev->dev_config);
 }
 
 static int tcmu_send_dev_config_event(struct tcmu_dev *udev,
                       const char *reconfig_data)
 {
     struct sk_buff *skb = NULL;
     void *msg_header = NULL;
     int ret = 0;
 
     ret = tcmu_netlink_event_init(udev, TCMU_CMD_RECONFIG_DEVICE,
                       &skb, &msg_header);
     if (ret < 0)
         return ret;
     ret = nla_put_string(skb, TCMU_ATTR_DEV_CFG, reconfig_data);
     if (ret < 0) {
         nlmsg_free(skb);
         return ret;
     }
     return tcmu_netlink_event_send(udev, TCMU_CMD_RECONFIG_DEVICE,
                        skb, msg_header);
 }
 
 
 static ssize_t tcmu_dev_config_store(struct config_item *item, const char *page,
                      size_t count)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                         struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
     int ret, len;
 
     len = strlen(page);
     if (!len || len > TCMU_CONFIG_LEN - 1)
         return -EINVAL;
 
     /* Check if device has been configured before */
     if (target_dev_configured(&udev->se_dev)) {
         ret = tcmu_send_dev_config_event(udev, page);
         if (ret) {
             pr_err("Unable to reconfigure device\n");
             return ret;
         }
         strlcpy(udev->dev_config, page, TCMU_CONFIG_LEN);
 
         ret = tcmu_update_uio_info(udev);
         if (ret)
             return ret;
         return count;
     }
     strlcpy(udev->dev_config, page, TCMU_CONFIG_LEN);
 
     return count;
 }
 CONFIGFS_ATTR(tcmu_, dev_config);
 
 static ssize_t tcmu_dev_size_show(struct config_item *item, char *page)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                         struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
 
     return snprintf(page, PAGE_SIZE, "%llu\n", udev->dev_size);
 }
 
 static int tcmu_send_dev_size_event(struct tcmu_dev *udev, u64 size)
 {
     struct sk_buff *skb = NULL;
     void *msg_header = NULL;
     int ret = 0;
 
     ret = tcmu_netlink_event_init(udev, TCMU_CMD_RECONFIG_DEVICE,
                       &skb, &msg_header);
     if (ret < 0)
         return ret;
     ret = nla_put_u64_64bit(skb, TCMU_ATTR_DEV_SIZE,
                 size, TCMU_ATTR_PAD);
     if (ret < 0) {
         nlmsg_free(skb);
         return ret;
     }
     return tcmu_netlink_event_send(udev, TCMU_CMD_RECONFIG_DEVICE,
                        skb, msg_header);
 }
 
 static ssize_t tcmu_dev_size_store(struct config_item *item, const char *page,
                    size_t count)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                         struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
     u64 val;
     int ret;
 
     ret = kstrtou64(page, 0, &val);
     if (ret < 0)
         return ret;
 
     /* Check if device has been configured before */
     if (target_dev_configured(&udev->se_dev)) {
         ret = tcmu_send_dev_size_event(udev, val);
         if (ret) {
             pr_err("Unable to reconfigure device\n");
             return ret;
         }
     }
     udev->dev_size = val;
     return count;
 }
 CONFIGFS_ATTR(tcmu_, dev_size);
 
 static ssize_t tcmu_nl_reply_supported_show(struct config_item *item,
         char *page)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                         struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
 
     return snprintf(page, PAGE_SIZE, "%d\n", udev->nl_reply_supported);
 }
 
 static ssize_t tcmu_nl_reply_supported_store(struct config_item *item,
         const char *page, size_t count)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                         struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
     s8 val;
     int ret;
 
     ret = kstrtos8(page, 0, &val);
     if (ret < 0)
         return ret;
 
     udev->nl_reply_supported = val;
     return count;
 }
 CONFIGFS_ATTR(tcmu_, nl_reply_supported);
 
 static ssize_t tcmu_emulate_write_cache_show(struct config_item *item,
                          char *page)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                     struct se_dev_attrib, da_group);
 
     return snprintf(page, PAGE_SIZE, "%i\n", da->emulate_write_cache);
 }
 
 static int tcmu_send_emulate_write_cache(struct tcmu_dev *udev, u8 val)
 {
     struct sk_buff *skb = NULL;
     void *msg_header = NULL;
     int ret = 0;
 
     ret = tcmu_netlink_event_init(udev, TCMU_CMD_RECONFIG_DEVICE,
                       &skb, &msg_header);
     if (ret < 0)
         return ret;
     ret = nla_put_u8(skb, TCMU_ATTR_WRITECACHE, val);
     if (ret < 0) {
         nlmsg_free(skb);
         return ret;
     }
     return tcmu_netlink_event_send(udev, TCMU_CMD_RECONFIG_DEVICE,
                        skb, msg_header);
 }
 
 static ssize_t tcmu_emulate_write_cache_store(struct config_item *item,
                           const char *page, size_t count)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                     struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
     u8 val;
     int ret;
 
     ret = kstrtou8(page, 0, &val);
     if (ret < 0)
         return ret;
 
     /* Check if device has been configured before */
     if (target_dev_configured(&udev->se_dev)) {
         ret = tcmu_send_emulate_write_cache(udev, val);
         if (ret) {
             pr_err("Unable to reconfigure device\n");
             return ret;
         }
     }
 
     da->emulate_write_cache = val;
     return count;
 }
 CONFIGFS_ATTR(tcmu_, emulate_write_cache);
 
 static ssize_t tcmu_tmr_notification_show(struct config_item *item, char *page)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                     struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
 
     return snprintf(page, PAGE_SIZE, "%i\n",
             test_bit(TCMU_DEV_BIT_TMR_NOTIFY, &udev->flags));
 }
 
 static ssize_t tcmu_tmr_notification_store(struct config_item *item,
                        const char *page, size_t count)
 {
     struct se_dev_attrib *da = container_of(to_config_group(item),
                     struct se_dev_attrib, da_group);
     struct tcmu_dev *udev = TCMU_DEV(da->da_dev);
     u8 val;
     int ret;
 
     ret = kstrtou8(page, 0, &val);
     if (ret < 0)
         return ret;
     if (val > 1)
         return -EINVAL;
 
     if (val)
         set_bit(TCMU_DEV_BIT_TMR_NOTIFY, &udev->flags);
     else
         clear_bit(TCMU_DEV_BIT_TMR_NOTIFY, &udev->flags);
     return count;
 }
 CONFIGFS_ATTR(tcmu_, tmr_notification);
 
 static ssize_t tcmu_block_dev_show(struct config_item *item, char *page)
 {
     struct se_device *se_dev = container_of(to_config_group(item),
                         struct se_device,
                         dev_action_group);
     struct tcmu_dev *udev = TCMU_DEV(se_dev);
 
     if (test_bit(TCMU_DEV_BIT_BLOCKED, &udev->flags))
         return snprintf(page, PAGE_SIZE, "%s\n", "blocked");
     else
         return snprintf(page, PAGE_SIZE, "%s\n", "unblocked");
 }
 
 static ssize_t tcmu_block_dev_store(struct config_item *item, const char *page,
                     size_t count)
 {
     struct se_device *se_dev = container_of(to_config_group(item),
                         struct se_device,
                         dev_action_group);
     struct tcmu_dev *udev = TCMU_DEV(se_dev);
     u8 val;
     int ret;
 
     if (!target_dev_configured(&udev->se_dev)) {
         pr_err("Device is not configured.\n");
         return -EINVAL;
     }
 
     ret = kstrtou8(page, 0, &val);
     if (ret < 0)
         return ret;
 
     if (val > 1) {
         pr_err("Invalid block value %d\n", val);
         return -EINVAL;
     }
 
     if (!val)
         tcmu_unblock_dev(udev);
     else
         tcmu_block_dev(udev);
     return count;
 }
 CONFIGFS_ATTR(tcmu_, block_dev);
 
 static ssize_t tcmu_reset_ring_store(struct config_item *item, const char *page,
                      size_t count)
 {
     struct se_device *se_dev = container_of(to_config_group(item),
                         struct se_device,
                         dev_action_group);
     struct tcmu_dev *udev = TCMU_DEV(se_dev);
     u8 val;
     int ret;
 
     if (!target_dev_configured(&udev->se_dev)) {
         pr_err("Device is not configured.\n");
         return -EINVAL;
     }
 
     ret = kstrtou8(page, 0, &val);
     if (ret < 0)
         return ret;
 
     if (val != 1 && val != 2) {
         pr_err("Invalid reset ring value %d\n", val);
         return -EINVAL;
     }
 
     tcmu_reset_ring(udev, val);
     return count;
 }
 CONFIGFS_ATTR_WO(tcmu_, reset_ring);
 
 static ssize_t tcmu_free_kept_buf_store(struct config_item *item, const char *page,
                     size_t count)
 {
     struct se_device *se_dev = container_of(to_config_group(item),
                         struct se_device,
                         dev_action_group);
     struct tcmu_dev *udev = TCMU_DEV(se_dev);
     struct tcmu_cmd *cmd;
     u16 cmd_id;
     int ret;
 
     if (!target_dev_configured(&udev->se_dev)) {
         pr_err("Device is not configured.\n");
         return -EINVAL;
     }
 
     ret = kstrtou16(page, 0, &cmd_id);
     if (ret < 0)
         return ret;
 
     mutex_lock(&udev->cmdr_lock);
 
     {
         XA_STATE(xas, &udev->commands, cmd_id);
 
         xas_lock(&xas);
         cmd = xas_load(&xas);
         if (!cmd) {
             pr_err("free_kept_buf: cmd_id %d not found\n", cmd_id);
             count = -EINVAL;
             xas_unlock(&xas);
             goto out_unlock;
         }
         if (!test_bit(TCMU_CMD_BIT_KEEP_BUF, &cmd->flags)) {
             pr_err("free_kept_buf: cmd_id %d was not completed with KEEP_BUF\n",
                    cmd_id);
             count = -EINVAL;
             xas_unlock(&xas);
             goto out_unlock;
         }
         xas_store(&xas, NULL);
         xas_unlock(&xas);
     }
 
     tcmu_cmd_free_data(cmd, cmd->dbi_cnt);
     tcmu_free_cmd(cmd);
     /*
      * We only freed data space, not ring space. Therefore we dont call
      * run_tmr_queue, but call run_qfull_queue if tmr_list is empty.
      */
     if (list_empty(&udev->tmr_queue))
         run_qfull_queue(udev, false);
 
 out_unlock:
     mutex_unlock(&udev->cmdr_lock);
     return count;
 }
 CONFIGFS_ATTR_WO(tcmu_, free_kept_buf);
 
 static struct configfs_attribute *tcmu_attrib_attrs[] = {
     &tcmu_attr_cmd_time_out,
     &tcmu_attr_qfull_time_out,
     &tcmu_attr_max_data_area_mb,
     &tcmu_attr_data_pages_per_blk,
     &tcmu_attr_cmd_ring_size_mb,
     &tcmu_attr_dev_config,
     &tcmu_attr_dev_size,
     &tcmu_attr_emulate_write_cache,
     &tcmu_attr_tmr_notification,
     &tcmu_attr_nl_reply_supported,
     NULL,
 };
 
 static struct configfs_attribute **tcmu_attrs;
 
 static struct configfs_attribute *tcmu_action_attrs[] = {
     &tcmu_attr_block_dev,
     &tcmu_attr_reset_ring,
     &tcmu_attr_free_kept_buf,
     NULL,
 };
 
 static struct target_backend_ops tcmu_ops = {
     .name           = "user",
     .owner          = THIS_MODULE,
     .transport_flags_default = TRANSPORT_FLAG_PASSTHROUGH,
     .transport_flags_changeable = TRANSPORT_FLAG_PASSTHROUGH_PGR |
                       TRANSPORT_FLAG_PASSTHROUGH_ALUA,
     .attach_hba     = tcmu_attach_hba,
     .detach_hba     = tcmu_detach_hba,
     .alloc_device       = tcmu_alloc_device,
     .configure_device   = tcmu_configure_device,
     .destroy_device     = tcmu_destroy_device,
     .free_device        = tcmu_free_device,
     .unplug_device      = tcmu_unplug_device,
     .plug_device        = tcmu_plug_device,
     .parse_cdb      = tcmu_parse_cdb,
     .tmr_notify     = tcmu_tmr_notify,
     .set_configfs_dev_params = tcmu_set_configfs_dev_params,
     .show_configfs_dev_params = tcmu_show_configfs_dev_params,
     .get_device_type    = sbc_get_device_type,
     .get_blocks     = tcmu_get_blocks,
     .tb_dev_action_attrs    = tcmu_action_attrs,
 };
 
 static void find_free_blocks(void)
 {
     struct tcmu_dev *udev;
     loff_t off;
     u32 pages_freed, total_pages_freed = 0;
     u32 start, end, block, total_blocks_freed = 0;
 
     if (atomic_read(&global_page_count) <= tcmu_global_max_pages)
         return;
 
     mutex_lock(&root_udev_mutex);
     list_for_each_entry(udev, &root_udev, node) {
         mutex_lock(&udev->cmdr_lock);
 
         if (!target_dev_configured(&udev->se_dev)) {
             mutex_unlock(&udev->cmdr_lock);
             continue;
         }
 
         /* Try to complete the finished commands first */
         if (tcmu_handle_completions(udev))
             run_qfull_queue(udev, false);
 
         /* Skip the udevs in idle */
         if (!udev->dbi_thresh) {
             mutex_unlock(&udev->cmdr_lock);
             continue;
         }
 
         end = udev->dbi_max + 1;
         block = find_last_bit(udev->data_bitmap, end);
         if (block == udev->dbi_max) {
             /*
              * The last bit is dbi_max, so it is not possible
              * reclaim any blocks.
              */
             mutex_unlock(&udev->cmdr_lock);
             continue;
         } else if (block == end) {
             /* The current udev will goto idle state */
             udev->dbi_thresh = start = 0;
             udev->dbi_max = 0;
         } else {
             udev->dbi_thresh = start = block + 1;
             udev->dbi_max = block;
         }
 
         /*
          * Release the block pages.
          *
          * Also note that since tcmu_vma_fault() gets an extra page
          * refcount, tcmu_blocks_release() won't free pages if pages
          * are mapped. This means it is safe to call
          * tcmu_blocks_release() before unmap_mapping_range() which
          * drops the refcount of any pages it unmaps and thus releases
          * them.
          */
         pages_freed = tcmu_blocks_release(udev, start, end - 1);
 
         /* Here will truncate the data area from off */
         off = udev->data_off + (loff_t)start * udev->data_blk_size;
         unmap_mapping_range(udev->inode->i_mapping, off, 0, 1);
 
         mutex_unlock(&udev->cmdr_lock);
 
         total_pages_freed += pages_freed;
         total_blocks_freed += end - start;
         pr_debug("Freed %u pages (total %u) from %u blocks (total %u) from %s.\n",
              pages_freed, total_pages_freed, end - start,
              total_blocks_freed, udev->name);
     }
     mutex_unlock(&root_udev_mutex);
 
     if (atomic_read(&global_page_count) > tcmu_global_max_pages)
         schedule_delayed_work(&tcmu_unmap_work, msecs_to_jiffies(5000));
 }
 
 static void check_timedout_devices(void)
 {
     struct tcmu_dev *udev, *tmp_dev;
     struct tcmu_cmd *cmd, *tmp_cmd;
     LIST_HEAD(devs);
 
     spin_lock_bh(&timed_out_udevs_lock);
     list_splice_init(&timed_out_udevs, &devs);
 
     list_for_each_entry_safe(udev, tmp_dev, &devs, timedout_entry) {
         list_del_init(&udev->timedout_entry);
         spin_unlock_bh(&timed_out_udevs_lock);
 
         mutex_lock(&udev->cmdr_lock);
 
         /*
          * If cmd_time_out is disabled but qfull is set deadline
          * will only reflect the qfull timeout. Ignore it.
          */
         if (udev->cmd_time_out) {
             list_for_each_entry_safe(cmd, tmp_cmd,
                          &udev->inflight_queue,
                          queue_entry) {
                 tcmu_check_expired_ring_cmd(cmd);
             }
             tcmu_set_next_deadline(&udev->inflight_queue,
                            &udev->cmd_timer);
         }
         list_for_each_entry_safe(cmd, tmp_cmd, &udev->qfull_queue,
                      queue_entry) {
             tcmu_check_expired_queue_cmd(cmd);
         }
         tcmu_set_next_deadline(&udev->qfull_queue, &udev->qfull_timer);
 
         mutex_unlock(&udev->cmdr_lock);
 
         spin_lock_bh(&timed_out_udevs_lock);
     }
 
     spin_unlock_bh(&timed_out_udevs_lock);
 }
 
 static void tcmu_unmap_work_fn(struct work_struct *work)
 {
     check_timedout_devices();
     find_free_blocks();
 }
 
 static int __init tcmu_module_init(void)
 {
     int ret, i, k, len = 0;
 
     BUILD_BUG_ON((sizeof(struct tcmu_cmd_entry) % TCMU_OP_ALIGN_SIZE) != 0);
 
     INIT_DELAYED_WORK(&tcmu_unmap_work, tcmu_unmap_work_fn);
 
     tcmu_cmd_cache = kmem_cache_create("tcmu_cmd_cache",
                 sizeof(struct tcmu_cmd),
                 __alignof__(struct tcmu_cmd),
                 0, NULL);
     if (!tcmu_cmd_cache)
         return -ENOMEM;
 
     tcmu_root_device = root_device_register("tcm_user");
     if (IS_ERR(tcmu_root_device)) {
         ret = PTR_ERR(tcmu_root_device);
         goto out_free_cache;
     }
 
     ret = genl_register_family(&tcmu_genl_family);
     if (ret < 0) {
         goto out_unreg_device;
     }
 
     for (i = 0; passthrough_attrib_attrs[i] != NULL; i++)
         len += sizeof(struct configfs_attribute *);
     for (i = 0; passthrough_pr_attrib_attrs[i] != NULL; i++)
         len += sizeof(struct configfs_attribute *);
     for (i = 0; tcmu_attrib_attrs[i] != NULL; i++)
         len += sizeof(struct configfs_attribute *);
     len += sizeof(struct configfs_attribute *);
 
     tcmu_attrs = kzalloc(len, GFP_KERNEL);
     if (!tcmu_attrs) {
         ret = -ENOMEM;
         goto out_unreg_genl;
     }
 
     for (i = 0; passthrough_attrib_attrs[i] != NULL; i++)
         tcmu_attrs[i] = passthrough_attrib_attrs[i];
     for (k = 0; passthrough_pr_attrib_attrs[k] != NULL; k++)
         tcmu_attrs[i++] = passthrough_pr_attrib_attrs[k];
     for (k = 0; tcmu_attrib_attrs[k] != NULL; k++)
         tcmu_attrs[i++] = tcmu_attrib_attrs[k];
     tcmu_ops.tb_dev_attrib_attrs = tcmu_attrs;
 
     ret = transport_backend_register(&tcmu_ops);
     if (ret)
         goto out_attrs;
 
     return 0;
 
 out_attrs:
     kfree(tcmu_attrs);
 out_unreg_genl:
     genl_unregister_family(&tcmu_genl_family);
 out_unreg_device:
     root_device_unregister(tcmu_root_device);
 out_free_cache:
     kmem_cache_destroy(tcmu_cmd_cache);
 
     return ret;
 }
 
 static void __exit tcmu_module_exit(void)
 {
     cancel_delayed_work_sync(&tcmu_unmap_work);
     target_backend_unregister(&tcmu_ops);
     kfree(tcmu_attrs);
     genl_unregister_family(&tcmu_genl_family);
     root_device_unregister(tcmu_root_device);
     kmem_cache_destroy(tcmu_cmd_cache);
 }
 
 MODULE_DESCRIPTION("TCM USER subsystem plugin");
 MODULE_AUTHOR("Shaohua Li <shli@kernel.org>");
 MODULE_AUTHOR("Andy Grover <agrover@redhat.com>");
 MODULE_LICENSE("GPL");
 
 module_init(tcmu_module_init);
 module_exit(tcmu_module_exit);