linux-2.6.25/request の履歴(No.104)

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パス: linux-2.6.25/include/linux/blkdev.h
FIXME: これは何？
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struct request {
        struct list_head queuelist;
        struct list_head donelist;

        struct request_queue *q;

        unsigned int cmd_flags;
        enum rq_cmd_type_bits cmd_type;

        /* Maintain bio traversal state for part by part I/O submission.
         * hard_* are block layer internals, no driver should touch them!
         */

        sector_t sector;                /* next sector to submit */
        sector_t hard_sector;           /* next sector to complete */
        unsigned long nr_sectors;       /* no. of sectors left to submit */
        unsigned long hard_nr_sectors;  /* no. of sectors left to complete */
        /* no. of sectors left to submit in the current segment */
        unsigned int current_nr_sectors;

        /* no. of sectors left to complete in the current segment */
        unsigned int hard_cur_sectors;

        struct bio *bio;
        struct bio *biotail;

        struct hlist_node hash; /* merge hash */
        /*
         * The rb_node is only used inside the io scheduler, requests
         * are pruned when moved to the dispatch queue. So let the
         * completion_data share space with the rb_node.
         */
        union {
                struct rb_node rb_node; /* sort/lookup */
                void *completion_data;
        };

        /*
         * two pointers are available for the IO schedulers, if they need
         * more they have to dynamically allocate it.
         */
        void *elevator_private;
        void *elevator_private2;

        struct gendisk *rq_disk;
        unsigned long start_time;

        /* Number of scatter-gather DMA addr+len pairs after
         * physical address coalescing is performed.
         */
        unsigned short nr_phys_segments;

        /* Number of scatter-gather addr+len pairs after
         * physical and DMA remapping hardware coalescing is performed.
         * This is the number of scatter-gather entries the driver
         * will actually have to deal with after DMA mapping is done.
         */
        unsigned short nr_hw_segments;

        unsigned short ioprio;

        void *special;
        char *buffer;

        int tag;
        int errors;

        int ref_count;

        /*
         * when request is used as a packet command carrier
         */
        unsigned int cmd_len;
        unsigned char cmd[BLK_MAX_CDB];

        unsigned int data_len;
        unsigned int extra_len; /* length of alignment and padding */
        unsigned int sense_len;
        void *data;
        void *sense;

        unsigned int timeout;
        int retries;

        /*
         * completion callback.
         */
        rq_end_io_fn *end_io;
        void *end_io_data;

        /* for bidi */
        struct request *next_rq;
};
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linux-2.6.25/request の履歴(No.104)

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