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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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05378940ca
Currently inherited from sg.c bsg will submit asynchronous request at the head-of-the-queue, (using "at_head" set in the call to blk_execute_rq_nowait()). This is bad in situation where the queues are full, requests will execute out of order, and can cause starvation of the first submitted requests. The sg_io_v4->flags member is used and a bit is allocated to denote the Q_AT_TAIL. Zero is to queue at_head as before, to be compatible with old code at the write/read path. SG_IO code path behavior was changed so to be the same as write/read behavior. SG_IO was very rarely used and breaking compatibility with it is OK at this stage. sg_io_hdr at sg.h also has a flags member and uses 3 bits from the first nibble and one bit from the last nibble. Even though none of these bits are supported by bsg, The second nibble is allocated for use by bsg. Just in case. Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> CC: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
93 lines
3.0 KiB
C
93 lines
3.0 KiB
C
#ifndef BSG_H
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#define BSG_H
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#define BSG_PROTOCOL_SCSI 0
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#define BSG_SUB_PROTOCOL_SCSI_CMD 0
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#define BSG_SUB_PROTOCOL_SCSI_TMF 1
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#define BSG_SUB_PROTOCOL_SCSI_TRANSPORT 2
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/*
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* For flags member below
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* sg.h sg_io_hdr also has bits defined for it's flags member. However
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* none of these bits are implemented/used by bsg. The bits below are
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* allocated to not conflict with sg.h ones anyway.
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*/
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#define BSG_FLAG_Q_AT_TAIL 0x10 /* default, == 0 at this bit, is Q_AT_HEAD */
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struct sg_io_v4 {
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__s32 guard; /* [i] 'Q' to differentiate from v3 */
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__u32 protocol; /* [i] 0 -> SCSI , .... */
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__u32 subprotocol; /* [i] 0 -> SCSI command, 1 -> SCSI task
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management function, .... */
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__u32 request_len; /* [i] in bytes */
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__u64 request; /* [i], [*i] {SCSI: cdb} */
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__u64 request_tag; /* [i] {SCSI: task tag (only if flagged)} */
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__u32 request_attr; /* [i] {SCSI: task attribute} */
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__u32 request_priority; /* [i] {SCSI: task priority} */
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__u32 request_extra; /* [i] {spare, for padding} */
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__u32 max_response_len; /* [i] in bytes */
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__u64 response; /* [i], [*o] {SCSI: (auto)sense data} */
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/* "dout_": data out (to device); "din_": data in (from device) */
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__u32 dout_iovec_count; /* [i] 0 -> "flat" dout transfer else
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dout_xfer points to array of iovec */
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__u32 dout_xfer_len; /* [i] bytes to be transferred to device */
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__u32 din_iovec_count; /* [i] 0 -> "flat" din transfer */
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__u32 din_xfer_len; /* [i] bytes to be transferred from device */
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__u64 dout_xferp; /* [i], [*i] */
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__u64 din_xferp; /* [i], [*o] */
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__u32 timeout; /* [i] units: millisecond */
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__u32 flags; /* [i] bit mask */
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__u64 usr_ptr; /* [i->o] unused internally */
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__u32 spare_in; /* [i] */
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__u32 driver_status; /* [o] 0 -> ok */
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__u32 transport_status; /* [o] 0 -> ok */
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__u32 device_status; /* [o] {SCSI: command completion status} */
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__u32 retry_delay; /* [o] {SCSI: status auxiliary information} */
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__u32 info; /* [o] additional information */
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__u32 duration; /* [o] time to complete, in milliseconds */
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__u32 response_len; /* [o] bytes of response actually written */
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__s32 din_resid; /* [o] din_xfer_len - actual_din_xfer_len */
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__s32 dout_resid; /* [o] dout_xfer_len - actual_dout_xfer_len */
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__u64 generated_tag; /* [o] {SCSI: transport generated task tag} */
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__u32 spare_out; /* [o] */
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__u32 padding;
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};
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#ifdef __KERNEL__
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#if defined(CONFIG_BLK_DEV_BSG)
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struct bsg_class_device {
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struct device *class_dev;
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struct device *parent;
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int minor;
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struct request_queue *queue;
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struct kref ref;
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void (*release)(struct device *);
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};
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extern int bsg_register_queue(struct request_queue *q,
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struct device *parent, const char *name,
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void (*release)(struct device *));
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extern void bsg_unregister_queue(struct request_queue *);
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#else
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static inline int bsg_register_queue(struct request_queue *q,
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struct device *parent, const char *name,
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void (*release)(struct device *))
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{
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return 0;
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}
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static inline void bsg_unregister_queue(struct request_queue *q)
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{
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}
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#endif
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#endif /* __KERNEL__ */
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#endif
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