diff options
Diffstat (limited to 'block/bsg.c')
| -rw-r--r-- | block/bsg.c | 525 |
1 files changed, 525 insertions, 0 deletions
diff --git a/block/bsg.c b/block/bsg.c new file mode 100644 index 000000000..2cbc1fcc8 --- /dev/null +++ b/block/bsg.c @@ -0,0 +1,525 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * bsg.c - block layer implementation of the sg v4 interface + */ +#include <linux/module.h> +#include <linux/init.h> +#include <linux/file.h> +#include <linux/blkdev.h> +#include <linux/cdev.h> +#include <linux/jiffies.h> +#include <linux/percpu.h> +#include <linux/idr.h> +#include <linux/bsg.h> +#include <linux/slab.h> + +#include <scsi/scsi.h> +#include <scsi/scsi_ioctl.h> +#include <scsi/scsi_cmnd.h> +#include <scsi/scsi_device.h> +#include <scsi/scsi_driver.h> +#include <scsi/sg.h> + +#define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver" +#define BSG_VERSION "0.4" + +#define bsg_dbg(bd, fmt, ...) \ + pr_debug("%s: " fmt, (bd)->name, ##__VA_ARGS__) + +struct bsg_device { + struct request_queue *queue; + spinlock_t lock; + struct hlist_node dev_list; + refcount_t ref_count; + char name[20]; + int max_queue; +}; + +#define BSG_DEFAULT_CMDS 64 +#define BSG_MAX_DEVS 32768 + +static DEFINE_MUTEX(bsg_mutex); +static DEFINE_IDR(bsg_minor_idr); + +#define BSG_LIST_ARRAY_SIZE 8 +static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE]; + +static struct class *bsg_class; +static int bsg_major; + +static inline struct hlist_head *bsg_dev_idx_hash(int index) +{ + return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)]; +} + +#define uptr64(val) ((void __user *)(uintptr_t)(val)) + +static int bsg_scsi_check_proto(struct sg_io_v4 *hdr) +{ + if (hdr->protocol != BSG_PROTOCOL_SCSI || + hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD) + return -EINVAL; + return 0; +} + +static int bsg_scsi_fill_hdr(struct request *rq, struct sg_io_v4 *hdr, + fmode_t mode) +{ + struct scsi_request *sreq = scsi_req(rq); + + if (hdr->dout_xfer_len && hdr->din_xfer_len) { + pr_warn_once("BIDI support in bsg has been removed.\n"); + return -EOPNOTSUPP; + } + + sreq->cmd_len = hdr->request_len; + if (sreq->cmd_len > BLK_MAX_CDB) { + sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL); + if (!sreq->cmd) + return -ENOMEM; + } + + if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len)) + return -EFAULT; + if (blk_verify_command(sreq->cmd, mode)) + return -EPERM; + return 0; +} + +static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr) +{ + struct scsi_request *sreq = scsi_req(rq); + int ret = 0; + + /* + * fill in all the output members + */ + hdr->device_status = sreq->result & 0xff; + hdr->transport_status = host_byte(sreq->result); + hdr->driver_status = driver_byte(sreq->result); + hdr->info = 0; + if (hdr->device_status || hdr->transport_status || hdr->driver_status) + hdr->info |= SG_INFO_CHECK; + hdr->response_len = 0; + + if (sreq->sense_len && hdr->response) { + int len = min_t(unsigned int, hdr->max_response_len, + sreq->sense_len); + + if (copy_to_user(uptr64(hdr->response), sreq->sense, len)) + ret = -EFAULT; + else + hdr->response_len = len; + } + + if (rq_data_dir(rq) == READ) + hdr->din_resid = sreq->resid_len; + else + hdr->dout_resid = sreq->resid_len; + + return ret; +} + +static void bsg_scsi_free_rq(struct request *rq) +{ + scsi_req_free_cmd(scsi_req(rq)); +} + +static const struct bsg_ops bsg_scsi_ops = { + .check_proto = bsg_scsi_check_proto, + .fill_hdr = bsg_scsi_fill_hdr, + .complete_rq = bsg_scsi_complete_rq, + .free_rq = bsg_scsi_free_rq, +}; + +static int bsg_sg_io(struct request_queue *q, fmode_t mode, void __user *uarg) +{ + struct request *rq; + struct bio *bio; + struct sg_io_v4 hdr; + int ret; + + if (copy_from_user(&hdr, uarg, sizeof(hdr))) + return -EFAULT; + + if (!q->bsg_dev.class_dev) + return -ENXIO; + + if (hdr.guard != 'Q') + return -EINVAL; + ret = q->bsg_dev.ops->check_proto(&hdr); + if (ret) + return ret; + + rq = blk_get_request(q, hdr.dout_xfer_len ? + REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0); + if (IS_ERR(rq)) + return PTR_ERR(rq); + + ret = q->bsg_dev.ops->fill_hdr(rq, &hdr, mode); + if (ret) { + blk_put_request(rq); + return ret; + } + + rq->timeout = msecs_to_jiffies(hdr.timeout); + if (!rq->timeout) + rq->timeout = q->sg_timeout; + if (!rq->timeout) + rq->timeout = BLK_DEFAULT_SG_TIMEOUT; + if (rq->timeout < BLK_MIN_SG_TIMEOUT) + rq->timeout = BLK_MIN_SG_TIMEOUT; + + if (hdr.dout_xfer_len) { + ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.dout_xferp), + hdr.dout_xfer_len, GFP_KERNEL); + } else if (hdr.din_xfer_len) { + ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr.din_xferp), + hdr.din_xfer_len, GFP_KERNEL); + } + + if (ret) + goto out_free_rq; + + bio = rq->bio; + + blk_execute_rq(q, NULL, rq, !(hdr.flags & BSG_FLAG_Q_AT_TAIL)); + ret = rq->q->bsg_dev.ops->complete_rq(rq, &hdr); + blk_rq_unmap_user(bio); + +out_free_rq: + rq->q->bsg_dev.ops->free_rq(rq); + blk_put_request(rq); + if (!ret && copy_to_user(uarg, &hdr, sizeof(hdr))) + return -EFAULT; + return ret; +} + +static struct bsg_device *bsg_alloc_device(void) +{ + struct bsg_device *bd; + + bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL); + if (unlikely(!bd)) + return NULL; + + spin_lock_init(&bd->lock); + bd->max_queue = BSG_DEFAULT_CMDS; + INIT_HLIST_NODE(&bd->dev_list); + return bd; +} + +static int bsg_put_device(struct bsg_device *bd) +{ + struct request_queue *q = bd->queue; + + mutex_lock(&bsg_mutex); + + if (!refcount_dec_and_test(&bd->ref_count)) { + mutex_unlock(&bsg_mutex); + return 0; + } + + hlist_del(&bd->dev_list); + mutex_unlock(&bsg_mutex); + + bsg_dbg(bd, "tearing down\n"); + + /* + * close can always block + */ + kfree(bd); + blk_put_queue(q); + return 0; +} + +static struct bsg_device *bsg_add_device(struct inode *inode, + struct request_queue *rq, + struct file *file) +{ + struct bsg_device *bd; + unsigned char buf[32]; + + lockdep_assert_held(&bsg_mutex); + + if (!blk_get_queue(rq)) + return ERR_PTR(-ENXIO); + + bd = bsg_alloc_device(); + if (!bd) { + blk_put_queue(rq); + return ERR_PTR(-ENOMEM); + } + + bd->queue = rq; + + refcount_set(&bd->ref_count, 1); + hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode))); + + strncpy(bd->name, dev_name(rq->bsg_dev.class_dev), sizeof(bd->name) - 1); + bsg_dbg(bd, "bound to <%s>, max queue %d\n", + format_dev_t(buf, inode->i_rdev), bd->max_queue); + + return bd; +} + +static struct bsg_device *__bsg_get_device(int minor, struct request_queue *q) +{ + struct bsg_device *bd; + + lockdep_assert_held(&bsg_mutex); + + hlist_for_each_entry(bd, bsg_dev_idx_hash(minor), dev_list) { + if (bd->queue == q) { + refcount_inc(&bd->ref_count); + goto found; + } + } + bd = NULL; +found: + return bd; +} + +static struct bsg_device *bsg_get_device(struct inode *inode, struct file *file) +{ + struct bsg_device *bd; + struct bsg_class_device *bcd; + + /* + * find the class device + */ + mutex_lock(&bsg_mutex); + bcd = idr_find(&bsg_minor_idr, iminor(inode)); + + if (!bcd) { + bd = ERR_PTR(-ENODEV); + goto out_unlock; + } + + bd = __bsg_get_device(iminor(inode), bcd->queue); + if (!bd) + bd = bsg_add_device(inode, bcd->queue, file); + +out_unlock: + mutex_unlock(&bsg_mutex); + return bd; +} + +static int bsg_open(struct inode *inode, struct file *file) +{ + struct bsg_device *bd; + + bd = bsg_get_device(inode, file); + + if (IS_ERR(bd)) + return PTR_ERR(bd); + + file->private_data = bd; + return 0; +} + +static int bsg_release(struct inode *inode, struct file *file) +{ + struct bsg_device *bd = file->private_data; + + file->private_data = NULL; + return bsg_put_device(bd); +} + +static int bsg_get_command_q(struct bsg_device *bd, int __user *uarg) +{ + return put_user(bd->max_queue, uarg); +} + +static int bsg_set_command_q(struct bsg_device *bd, int __user *uarg) +{ + int queue; + + if (get_user(queue, uarg)) + return -EFAULT; + if (queue < 1) + return -EINVAL; + + spin_lock_irq(&bd->lock); + bd->max_queue = queue; + spin_unlock_irq(&bd->lock); + return 0; +} + +static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + struct bsg_device *bd = file->private_data; + void __user *uarg = (void __user *) arg; + + switch (cmd) { + /* + * Our own ioctls + */ + case SG_GET_COMMAND_Q: + return bsg_get_command_q(bd, uarg); + case SG_SET_COMMAND_Q: + return bsg_set_command_q(bd, uarg); + + /* + * SCSI/sg ioctls + */ + case SG_GET_VERSION_NUM: + case SCSI_IOCTL_GET_IDLUN: + case SCSI_IOCTL_GET_BUS_NUMBER: + case SG_SET_TIMEOUT: + case SG_GET_TIMEOUT: + case SG_GET_RESERVED_SIZE: + case SG_SET_RESERVED_SIZE: + case SG_EMULATED_HOST: + return scsi_cmd_ioctl(bd->queue, NULL, file->f_mode, cmd, uarg); + case SG_IO: + return bsg_sg_io(bd->queue, file->f_mode, uarg); + case SCSI_IOCTL_SEND_COMMAND: + pr_warn_ratelimited("%s: calling unsupported SCSI_IOCTL_SEND_COMMAND\n", + current->comm); + return -EINVAL; + default: + return -ENOTTY; + } +} + +static const struct file_operations bsg_fops = { + .open = bsg_open, + .release = bsg_release, + .unlocked_ioctl = bsg_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .owner = THIS_MODULE, + .llseek = default_llseek, +}; + +void bsg_unregister_queue(struct request_queue *q) +{ + struct bsg_class_device *bcd = &q->bsg_dev; + + if (!bcd->class_dev) + return; + + mutex_lock(&bsg_mutex); + idr_remove(&bsg_minor_idr, bcd->minor); + if (q->kobj.sd) + sysfs_remove_link(&q->kobj, "bsg"); + device_unregister(bcd->class_dev); + bcd->class_dev = NULL; + mutex_unlock(&bsg_mutex); +} +EXPORT_SYMBOL_GPL(bsg_unregister_queue); + +int bsg_register_queue(struct request_queue *q, struct device *parent, + const char *name, const struct bsg_ops *ops) +{ + struct bsg_class_device *bcd; + dev_t dev; + int ret; + struct device *class_dev = NULL; + + /* + * we need a proper transport to send commands, not a stacked device + */ + if (!queue_is_mq(q)) + return 0; + + bcd = &q->bsg_dev; + memset(bcd, 0, sizeof(*bcd)); + + mutex_lock(&bsg_mutex); + + ret = idr_alloc(&bsg_minor_idr, bcd, 0, BSG_MAX_DEVS, GFP_KERNEL); + if (ret < 0) { + if (ret == -ENOSPC) { + printk(KERN_ERR "bsg: too many bsg devices\n"); + ret = -EINVAL; + } + goto unlock; + } + + bcd->minor = ret; + bcd->queue = q; + bcd->ops = ops; + dev = MKDEV(bsg_major, bcd->minor); + class_dev = device_create(bsg_class, parent, dev, NULL, "%s", name); + if (IS_ERR(class_dev)) { + ret = PTR_ERR(class_dev); + goto idr_remove; + } + bcd->class_dev = class_dev; + + if (q->kobj.sd) { + ret = sysfs_create_link(&q->kobj, &bcd->class_dev->kobj, "bsg"); + if (ret) + goto unregister_class_dev; + } + + mutex_unlock(&bsg_mutex); + return 0; + +unregister_class_dev: + device_unregister(class_dev); +idr_remove: + idr_remove(&bsg_minor_idr, bcd->minor); +unlock: + mutex_unlock(&bsg_mutex); + return ret; +} + +int bsg_scsi_register_queue(struct request_queue *q, struct device *parent) +{ + if (!blk_queue_scsi_passthrough(q)) { + WARN_ONCE(true, "Attempt to register a non-SCSI queue\n"); + return -EINVAL; + } + + return bsg_register_queue(q, parent, dev_name(parent), &bsg_scsi_ops); +} +EXPORT_SYMBOL_GPL(bsg_scsi_register_queue); + +static struct cdev bsg_cdev; + +static char *bsg_devnode(struct device *dev, umode_t *mode) +{ + return kasprintf(GFP_KERNEL, "bsg/%s", dev_name(dev)); +} + +static int __init bsg_init(void) +{ + int ret, i; + dev_t devid; + + for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++) + INIT_HLIST_HEAD(&bsg_device_list[i]); + + bsg_class = class_create(THIS_MODULE, "bsg"); + if (IS_ERR(bsg_class)) + return PTR_ERR(bsg_class); + bsg_class->devnode = bsg_devnode; + + ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg"); + if (ret) + goto destroy_bsg_class; + + bsg_major = MAJOR(devid); + + cdev_init(&bsg_cdev, &bsg_fops); + ret = cdev_add(&bsg_cdev, MKDEV(bsg_major, 0), BSG_MAX_DEVS); + if (ret) + goto unregister_chrdev; + + printk(KERN_INFO BSG_DESCRIPTION " version " BSG_VERSION + " loaded (major %d)\n", bsg_major); + return 0; +unregister_chrdev: + unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS); +destroy_bsg_class: + class_destroy(bsg_class); + return ret; +} + +MODULE_AUTHOR("Jens Axboe"); +MODULE_DESCRIPTION(BSG_DESCRIPTION); +MODULE_LICENSE("GPL"); + +device_initcall(bsg_init); |