ceph存储 scsi设备驱动体系架构

位 7

位 6

位 5

位 4

位 3

位 2

位 1

位 0

字节 0

Operation code = 12h

字节 1

LUN

Reserved

EVPD

字节 2

Page code

字节 3

Reserved

字节 4

Allocation length

字节 5

Control

#define TEST_UNIT_READY       0x00

#define REZERO_UNIT           0x01

#define REQUEST_SENSE         0x03

#define FORMAT_UNIT           0x04

#define READ_BLOCK_LIMITS     0x05

#define REASSIGN_BLOCKS       0x07

#define INITIALIZE_ELEMENT_STATUS 0x07

#define READ_6                0x08

#define WRITE_6               0x0a

#define SEEK_6                0x0b

#define READ_REVERSE          0x0f

#define WRITE_FILEMARKS       0x10

#define SPACE                 0x11

#define INQUIRY               0x12

#define RECOVER_BUFFERED_DATA 0x14

#define MODE_SELECT           0x15

#define RESERVE               0x16

#define RELEASE               0x17

#define COPY                  0x18

#define ERASE                 0x19

#define MODE_SENSE            0x1a

#define START_STOP            0x1b

#define RECEIVE_DIAGNOSTIC    0x1c

#define SEND_DIAGNOSTIC       0x1d

#define ALLOW_MEDIUM_REMOVAL  0x1e

#define SET_WINDOW            0x24

#define READ_CAPACITY         0x25

#define READ_10               0x28

#define WRITE_10              0x2a

#define SEEK_10               0x2b

#define POSITION_TO_ELEMENT   0x2b

#define WRITE_VERIFY          0x2e

#define VERIFY                0x2f

#define SEARCH_HIGH           0x30

#define SEARCH_EQUAL          0x31

#define SEARCH_LOW            0x32

#define SET_LIMITS            0x33

#define PRE_FETCH             0x34

#define READ_POSITION         0x34

#define SYNCHRONIZE_CACHE     0x35

#define LOCK_UNLOCK_CACHE     0x36

#define READ_DEFECT_DATA      0x37

#define MEDIUM_SCAN           0x38

#define COMPARE               0x39

#define COPY_VERIFY           0x3a

#define WRITE_BUFFER          0x3b

#define READ_BUFFER           0x3c

#define UPDATE_BLOCK          0x3d

#define READ_LONG             0x3e

#define WRITE_LONG            0x3f

#define CHANGE_DEFINITION     0x40

#define WRITE_SAME            0x41

#define READ_TOC              0x43

#define LOG_SELECT            0x4c

#define LOG_SENSE             0x4d

#define MODE_SELECT_10        0x55

#define RESERVE_10            0x56

#define RELEASE_10            0x57

#define MODE_SENSE_10         0x5a

#define PERSISTENT_RESERVE_IN 0x5e

#define PERSISTENT_RESERVE_OUT 0x5f

#define REPORT_LUNS           0xa0

#define MOVE_MEDIUM           0xa5

#define EXCHANGE_MEDIUM       0xa6

#define READ_12               0xa8

#define WRITE_12              0xaa

#define WRITE_VERIFY_12       0xae

#define SEARCH_HIGH_12        0xb0

#define SEARCH_EQUAL_12       0xb1

#define SEARCH_LOW_12         0xb2

#define READ_ELEMENT_STATUS   0xb8

#define SEND_VOLUME_TAG       0xb6

#define WRITE_LONG_2          0xea

#define READ_16               0x88

#define WRITE_16              0x8a

#define VERIFY_16            0x8f

#define SERVICE_ACTION_IN     0x9e

/* values for service action in */

#define    SAI_READ_CAPACITY_16  0x10

/* Values for T10/04-262r7 */

#define    ATA_16                0x85    /* 16-byte pass-thru */

#define    ATA_12                0xa1    /* 12-byte pass-thru */

命令

描述

INQUIRY

请求目标设备的摘要信息

TEST_UNIT_READY

检测目标设备是否准备好进行传输

READ_6

从 SCSI 目标设备传输数据

WRITE_6

向 SCSI 目标设备传输数据

REQUEST_SENSE

请求最后一个命令的检测数据

READ_CAPACITY

获得存储容量信息

struct scsi_cmnd {

       struct scsi_device *device;

       struct list_head list;  /* scsi_cmnd participates in queue lists */

       struct list_head eh_entry; /* entry for the host eh_cmd_q */

       int eh_eflags;         /* Used by error handlr */

       void (*done) (struct scsi_cmnd *);       /* Mid-level done function */

       unsigned long serial_number;

       unsigned long jiffies_at_alloc;

       int retries;

       int allowed;

       int timeout_per_command;

       unsigned char cmd_len;

       enum dma_data_direction sc_data_direction;

       /* These elements define the operation we are about to perform */

#define MAX_COMMAND_SIZE       16

       unsigned char cmnd[MAX_COMMAND_SIZE];

       unsigned request_bufflen;      /* Actual request size */

       struct timer_list eh_timeout;  /* Used to time out the command. */

       void *request_buffer;            /* Actual requested buffer */

       /* These elements define the operation we ultimately want to perform */

       unsigned short use_sg;   /* Number of pieces of scatter-gather */

       unsigned short sglist_len;      /* size of malloc'd scatter-gather list */

       unsigned underflow;     

       unsigned transfersize;    

       int resid;        

       struct request *request;

#define SCSI_SENSE_BUFFERSIZE        96

       unsigned char sense_buffer[SCSI_SENSE_BUFFERSIZE];

                            /* obtained by REQUEST SENSE when

                             * CHECK CONDITION is received on original

                             * command (auto-sense) */

       void (*scsi_done) (struct scsi_cmnd *);

       struct scsi_pointer SCp;  /* Scratchpad used by some host adapters */

       unsigned char *host_scribble;      

       int result;        /* Status code from lower level driver */

       unsigned char tag;  /* SCSI-II queued command tag */

       unsigned long pid;  /* Process ID, starts at 0. Unique per host. */

};