[v3,0/8] sg: major cleanup, remove max_queue limit

Message

Douglas Gilbert Oct. 26, 2018, 11:48 a.m. UTC

The intention is to add two new ioctls as proposed by Linus Torvalds:
SG_IOSUBMIT and SG_IORECEIVE to replace the write()/read() async
interface.

But first, clean up the driver and remove the SG_MAX_QUEUE limit of
no more than 16 queued commands on a file descriptor at a time. A
free list has been added and the de-allocation of sg_request
objects is deferred until the close() of a file. Locking is
extensively reworked, especially at the struct sg_fd and
sg_request level.

A new SG_SET_GET_EXTENDED ioctl has been added. It allows multiple
integer values and booleans to be written to and/or read from the
driver. An example is changing and/or reading the reserved request
data length (there is one of these per fd). An example of a new
feature is changing and/or reading the per-fd upper limit on the
sum of outstanding data buffer sizes (default is 16 MB). An
example of a boolean is a bit to do all following command
timekeeping in nanoseconds rather that the default millseconds.

A later patchset will add implementations for the SG_IOSUBMIT and
SG_IORECEIVE plus handling of the sg v4 interface with the
existing SG_IO ioctl.

This patchset is against Martin Petersen's 4.20/scsi-queue branch.

ToDo:
  - work out more modern technique for logging function invocations
    info with some error paths.

Changes since v2:
  - fix problem with reserve request not being placed on fl
  - fix locking problem with sg_reserved_sz()
  - fix sum_fd_dlens counting problem
  - change new ioctl base numbers back to 0x22
  - arrange fl in ascending dlen order apart from dlen=0
    entries at tail
  - SG_GET_REQUEST_TABLE ioctl first fill from active list
    then, if there is room, it fills from the free list
  - add SG_SEIRV_DEV_FL_RQS to fetch count of all free list
    entries on the device the fd is associated with

Changes since v1:
  - remove redundant casts from private_data field
  - introduce atomic to address locking problems around
    sg_fd::sum_fd_dlens
  - replace rq_state defines with an enumeration
  - add __must_hold() annotation to sg_fill_request_table()
  - fix compile/build problem around the 4th and 5th patches
  - add read_value[SG_SEIRV_*] options in SG_SET_GET_EXTENDED
    ioctl and increase structure size from 64 to 96 bytes


Douglas Gilbert (8):
  sg: types and naming cleanup
  sg: introduce sg_log macro
  sg: split header, expand and correct descriptions
  sg: expand request states
  sg: add free list, rework locking
  sg: complete locking changes on ioctl+debug
  sg: rework ioctl handling
  sg: user controls for q_at_head, read_value

 drivers/scsi/sg.c      | 2621 ++++++++++++++++++++++++++--------------
 include/scsi/sg.h      |  268 +---
 include/uapi/scsi/sg.h |  414 +++++++
 3 files changed, 2156 insertions(+), 1147 deletions(-)
 create mode 100644 include/uapi/scsi/sg.h

Comments

Douglas Gilbert Oct. 28, 2018, 11:56 p.m. UTC | #1

For anyone thinking of testing this patchset, it also applies clean to
lk 4.19 release.

Doug Gilbert

On 2018-10-26 12:48 p.m., Douglas Gilbert wrote:
> The intention is to add two new ioctls as proposed by Linus Torvalds:
> SG_IOSUBMIT and SG_IORECEIVE to replace the write()/read() async
> interface.
> 
> But first, clean up the driver and remove the SG_MAX_QUEUE limit of
> no more than 16 queued commands on a file descriptor at a time. A
> free list has been added and the de-allocation of sg_request
> objects is deferred until the close() of a file. Locking is
> extensively reworked, especially at the struct sg_fd and
> sg_request level.
> 
> A new SG_SET_GET_EXTENDED ioctl has been added. It allows multiple
> integer values and booleans to be written to and/or read from the
> driver. An example is changing and/or reading the reserved request
> data length (there is one of these per fd). An example of a new
> feature is changing and/or reading the per-fd upper limit on the
> sum of outstanding data buffer sizes (default is 16 MB). An
> example of a boolean is a bit to do all following command
> timekeeping in nanoseconds rather that the default millseconds.
> 
> A later patchset will add implementations for the SG_IOSUBMIT and
> SG_IORECEIVE plus handling of the sg v4 interface with the
> existing SG_IO ioctl.
> 
> This patchset is against Martin Petersen's 4.20/scsi-queue branch.
> 
> ToDo:
>    - work out more modern technique for logging function invocations
>      info with some error paths.
> 
> Changes since v2:
>    - fix problem with reserve request not being placed on fl
>    - fix locking problem with sg_reserved_sz()
>    - fix sum_fd_dlens counting problem
>    - change new ioctl base numbers back to 0x22
>    - arrange fl in ascending dlen order apart from dlen=0
>      entries at tail
>    - SG_GET_REQUEST_TABLE ioctl first fill from active list
>      then, if there is room, it fills from the free list
>    - add SG_SEIRV_DEV_FL_RQS to fetch count of all free list
>      entries on the device the fd is associated with
> 
> Changes since v1:
>    - remove redundant casts from private_data field
>    - introduce atomic to address locking problems around
>      sg_fd::sum_fd_dlens
>    - replace rq_state defines with an enumeration
>    - add __must_hold() annotation to sg_fill_request_table()
>    - fix compile/build problem around the 4th and 5th patches
>    - add read_value[SG_SEIRV_*] options in SG_SET_GET_EXTENDED
>      ioctl and increase structure size from 64 to 96 bytes
> 
> 
> Douglas Gilbert (8):
>    sg: types and naming cleanup
>    sg: introduce sg_log macro
>    sg: split header, expand and correct descriptions
>    sg: expand request states
>    sg: add free list, rework locking
>    sg: complete locking changes on ioctl+debug
>    sg: rework ioctl handling
>    sg: user controls for q_at_head, read_value
> 
>   drivers/scsi/sg.c      | 2621 ++++++++++++++++++++++++++--------------
>   include/scsi/sg.h      |  268 +---
>   include/uapi/scsi/sg.h |  414 +++++++
>   3 files changed, 2156 insertions(+), 1147 deletions(-)
>   create mode 100644 include/uapi/scsi/sg.h
>