Okay, this is the final version of the sd patch to remove sd_dsk_arr.
Instead of keeping a big global array we allocate one structure for
each disk dynamically in sd_attach.  We can use the higher level
private data to access it almost everywhere, for the few other
places we keep a linked list of all disks (these are walked only
in slow-patheß).

This patch also allows to get rid of the sd_init midlayer method and
the CONFIG_SD_EXTRA_DEVS option - sd has no more static limit to
the number of disk except of the number of assigned majors.

Hi James,

Here are the changes that are good outside the other changes :-)

scsi_lib:
	o ->errors is used as the scsi status byte for REQ_BLOCK_PC
	o ->data_len is the residual byte count
	o call __scsi_end_request even for !good_sectors if status is
	  good. This legitimately can happen for REQ_BLOCK_PC commands
	  sent from a user space program, if it gets the command setup
	  wrong (or weird). Right now this will hang that queue.

scsi_merge:
	o set SCpnt->request_bufflen to ->data_len, this is the
	  authoritative io byte count for REQ_BLOCK_PC. Here we deal in
	  bytes and not sectors.

sr + sd:
	o Set transfersize and underlow correctly for REQ_BLOCK_PC

sr_ioctl
	o We want to return -EIO for command failure, not EINVAL. That
 	  is pretty stupid :-)


===== drivers/scsi/scsi_lib.c 1.35 vs edited =====

bring it back in line with sd:
* get rid of typedefs where possible
* tab-align all credits entries
* line-wrap after 80 characters
* use C99-initializers

Cleanup the last_merge logic. There are two reasons for clearing
last_merge when we are dealing with integrity, and these are:

o Clear when handing the request to the driver, so we don't merge on
  a started request.

o Clear when a request is taken off the list. This cannot be done from
  the driver (above case would already have been hit), but it can
  happen
  when we merge two requests.

This makes it a lot nicer, it was always peculiar how we cleared in
put_request.

Make it possible for a device to specify the dma alignment restrictions
it has. This will be used by future infrastructure when mapping in user
pages, and allows us to dma to on ATAPI even though user address and
length is not sector size aligned.

Extend q->prep_rq_fn() to return one of three values:

 o BLKPREP_OK: request is good, return it
 o BLKPREP_KILL: request is bad, end it completely
 o BLKPREP_DEFER: request is good, but we can't take it now

We maintain compatability with old prep functions (if any, outside of
ide-cd). This change is needed or SCSI to use prep function for command
init, if sg table allocation fails we can just defer the request.

Add some missing bits, and make it generally a bit more useful outside
of REQ_PC requests.

Request insertion in the current tree is a mess. We have all sorts of
variants of *elv_add_request*, and it's not at all clear who does what
and with what locks (or not). This patch cleans it up to be:

o __elv_add_request(queue, request, at_end, plug)
      Core function, requires queue lock to be held

o elv_add_request(queue, request, at_end, plug)
      Like __elv_add_request(), but grabs queue lock

o __elv_add_request_pos(queue, request, position)
      Insert request at a given location, lock must be held

We must return -EIO if the command fails (the 5/20/00 sense check is
just helping return more sane info), not -EINVAL. Getting -EINVAL return
on an ioctl if a command fails is less than helpful for applications...

o Split blk_queue_bounce() into a slow and fast path. The fast path is
  inlined, only if we actually need to check the bio for possible
  bounces (and bounce) do we enter __blk_queue_bounce() slow path.

o Fix a nasty bug that could cause corruption for file systems not
  using PAGE_CACHE_SIZE blok size! We were not correctly setting the
  'to' bv_offset correctly.

o Add BIO_BOUNCE flag. Later patches will use this for debug checking.

Make deadline_merge() prefetch the next entry on the list.

wake_up_interruptible() and _sync() calls are reversed in pipe_read().

The attached patches only calls _sync if a schedule() call follows.

On Mon, Oct 28, 2002 at 01:50:53AM +0100, Andries Brouwer wrote:
> On Sun, Oct 27, 2002 at 06:05:07PM -0600, James Bottomley wrote:
>
> > If the return type will be ignored by most applications, I don't see
> > what the problem is.
>
> There is no problem. My longish reaction was mostly because you used
> "future proofing", that gave the impression that you did not know
> what this is about.
>
> > (like an obviously wrong truncation)
>
> No, the code I wrote was optimal.
> If you have 16 bits and the value is 70000, I prefer returning
> 65535 over 4464.

Why didn't you write is as patch?  James, this in Andries code
in patch from, it get's rid of the ugly sector_div so it should
be in if not just because of that.

sector_div has the same slightly strange calling convention do_div has:
it's return value is the modulo of the two operators, the division
result is in the first parameter.  Also optimize one of the expensive
64bit division away (okay, okay - it's not exactly an fast-path :))

Add a pointer to struct scsi_disk instead.  This also obsoletes
sd_dskname().

Now that only sd.c includes sd.h it can be safely merged into it.
Also get rid of typedef abuse in sd.c

sorry, the last patch I sent you contained a bogus change
for include/linux/init.h (to get around a local compile problem).

This patch backs it out.

Thanks to Patrick Mansfield for pointing this out.

Currnetly the ->bios_param for host drivers exposes struct scsi_disk
(aka Scsi_Disk or Disk) to each and every lowlevel driver, although
this structure should be privated to the sd driver.

All bios_param implementation do only use two fields:  .device and
.capacity.  This patch passes down those two directly and gets
rid of 99% of the sd.h inclusions (*).

I've tried to not break any driver with this patch, but given the
number of compiler errors in the current tree I might have missed
one or two.

(*) a bunch of drivers needed sd.h to get to scsi.h, I've fixed those.

into mulgrave.(none):/home/jejb/BK/scsi-misc-2.5

In 2.5.44 it contains only two functions, that both have exactly
one caller in other files and both are entirely unrelated to
request merging..

into aladin.rdu.redhat.com:/usr/src/2.5

the ->finish method is a relicat from the old day were we never had
hotplugging and allowed the driver to do fixups after all busses
had been scanned.  Nowdays only sd and sr actually implement it,
and both only defer actions to there that should actually happen in
->attach.  Change both drivers to move that code into ->attach,
clenaup the Templates to use C99 initializers and get rid of the
methods.

This also cleans up some very crude race-avoidable code in those
drivers, btw..

From Mike Anderson and Patrick Mansfield

On Fri, Oct 18, 2002 at 04:18:15PM -0500, James Bottomley wrote:
> hch@lst.de said:
> > In current 2.5 each scsi highlevel driver registers with the driver
> > model individually.   This is rather messy and in fact one driver was
> > left out in the change.  Make scsi_{,un}register_device do it instead
> > and deregister with the driver model first as we registered last.
>
> OK, Patrick Mochel just stomped all over this.  So I no longer trust my merge
> corrections.  Could you resend against the current 2.5-BK.

Patch below (Template changes will be part of a different patch
now)

When a scsi device is offlined and then the system is shutdown it will
hang during the synchronizing SCSI caches task. The error handler was
activated during this step, but post recovery the system did not
complete the shutdown.

This patch just adds a check for online before sending the command. The
better approach appeared to be to use scsi_block_when_processing_errors,
but I was concerned that we might block to long in a shutdown case.

-andmike
--
Michael Anderson
andmike@us.ibm.com

 sd.c |    3 +++
 1 files changed, 3 insertions(+)