Douglas Gilbert <dougg@xxxxxxxxxx> wrote ...
> struct sg_io_v4 {
> __s32 guard; /* [i] 'Q' to differentiate from v3 */
> __u32 protocol; /* [i] 0 -> SCSI , .... */
> __u32 subprotocol; /* [i] 0 -> SCSI command, 1 -> SCSI task
> management function, .... */
>
> __u32 request_len; /* [i] in bytes */
> __u64 request; /* [i], [*i] {SCSI: cdb} */
> __u64 request_tag; /* [i] {SCSI: task tag (only if flagged)} */
> __u32 request_attr; /* [i] {SCSI: task attribute} */
> __u32 request_priority; /* [i] {SCSI: task priority} */
> __u32 request_extra; /* [i] {spare, for padding} */
> __u32 max_response_len; /* [i] in bytes */
> __u64 response; /* [i], [*o] {SCSI: (auto)sense data} */
>
> /* "dout_": data out (to device); "din_": data in (from device) */
> __u32 dout_iovec_count; /* [i] 0 -> "flat" dout transfer else
> dout_xfer points to array of iovec */
> __u32 dout_xfer_len; /* [i] bytes to be transferred to device */
> __u32 din_iovec_count; /* [i] 0 -> "flat" din transfer */
> __u32 din_xfer_len; /* [i] bytes to be transferred from device */
> __u64 dout_xferp; /* [i], [*i] */
> __u64 din_xferp; /* [i], [*o] */
>
> __u32 timeout; /* [i] units: millisecond */
> __u32 flags; /* [i] bit mask */
> __u64 usr_ptr; /* [i->o] unused internally */
> __u32 spare_in; /* [i] */
> ...
Currently because of a twisted accident sg and bsg queue their async
request with the "at_head" flag set when calling blk_execute_rq_nowait.
Since sg_io_v4 is new and as plenty of possible choices, what would be
the best place to put the "at_head" flag?
Douglas ?
What was your intention with the above:
__u32 request_priority; /* [i] {SCSI: task priority} */
[And while at it, what was:
__u32 request_attr; /* [i] {SCSI: task attribute} */
]
Should I define (bsg.h):
enum {
BSG_AT_HEAD = 0, /* compatible with old code */
BSG_AT_TAIL,
}
And put it in request_priority
or define:
#define SG_FLAG_AT_TAIL 0x10 /* See sg.h for more/other flags (sg.h flags are ignored by bsg) */
And OR that into the old flags member that is otherwise
unused by current bsg code
Thanks
Boaz
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
