linux-toradex.git/drivers/scsi/scsi.c, branch v2.6.27.6

[SCSI] Support devices with protection information

2008-07-26T19:14:55+00:00

Implement support for DMA of protection information for devices that
are data integrity capable.

 - Add support for mapping an extra scatter-gather list containing
   the protection information.

 - Allocate protection scsi_data_buffer if host is DIX (integrity DMA)
   capable.

 - Accessor function for checking whether a device has protection
   enabled.

Signed-off-by: Martin K. Petersen 
Signed-off-by: James Bottomley

[SCSI] fix shared tag map setup

2008-07-26T19:14:48+00:00

Currently qla4xxx and stex pass in their can_queue values into
scsi_activate_tcq because they wanted the tag map that large.
The problem with this is that it ends up also setting the queue
depth to that large value. All we want to do this in this case
is set the device queue depth and the other device settings.
We do not need to touch the tag map sizing because the drivers
had setup that map according to their can_queue limits when the
shared map was created.

The scsi mid layer in request_fn will then handle the case where we
have more requests than available tags when it checks the host
queue ready function.

Signed-off-by: Mike Christie 
Signed-off-by: James Bottomley

[SCSI] make use of the residue value

2008-06-05T14:23:45+00:00

USB sometimes doesn't return an error but instead returns a residue
value indicating part (or all) of the command wasn't completed.  So if
the driver _done() error processing indicates the command was fully
processed, subtract off the residue so that this USB error gets
propagated.

Cc: Alan Stern 
Signed-off-by: James Bottomley

[SCSI] add support for variable length extended commands

2008-05-02T16:33:25+00:00

Add support for variable-length, extended, and vendor specific
CDBs to scsi-ml. It is now possible for initiators and ULD's
to issue these types of commands. LLDs need not change much.
All they need is to raise the .max_cmd_len to the longest command
they support (see iscsi patch).

- clean-up some code paths that did not expect commands to be
  larger than 16, and change cmd_len members' type to short as
  char is not enough.

Signed-off-by: Boaz Harrosh 
Signed-off-by: Benny Halevy 
Signed-off-by: James Bottomley

[SCSI] bug fix for free list handling

2008-04-30T00:37:32+00:00

commit:

commit 542bd1377a963070bc4a03ff7d2690ddf3920596
Author: James Bottomley 
Date:   Mon Apr 21 10:57:20 2008 -0500

    [SCSI] fix SLUB WARN_ON

Fixed another problem in free list handling by moving list allocation
from scsi_host_alloc() to scsi_add_host().  Unfortunately it
introduced a new failure mode in that hosts can pass straight from
alloc to put without going through add, leaving the free list
uninitialised.

Fix by checking shost->cmd_pool on the release path to see if it got
initialised.

Signed-off-by: Alan D. Brunelle 
Signed-off-by: James Bottomley

block: move the padding adjustment to blk_rq_map_sg

2008-04-21T07:50:08+00:00

blk_rq_map_user adjusts bi_size of the last bio. It breaks the rule
that req->data_len (the true data length) is equal to sum(bio). It
broke the scsi command completion code.

commit e97a294ef6938512b655b1abf17656cf2b26f709 was introduced to fix
the above issue. However, the partial completion code doesn't work
with it. The commit is also a layer violation (scsi mid-layer should
not know about the block layer's padding).

This patch moves the padding adjustment to blk_rq_map_sg (suggested by
James). The padding works like the drain buffer. This patch breaks the
rule that req->data_len is equal to sum(sg), however, the drain buffer
already broke it. So this patch just restores the rule that
req->data_len is equal to sub(bio) without breaking anything new.

Now when a low level driver needs padding, blk_rq_map_user and
blk_rq_map_user_iov guarantee there's enough room for padding.
blk_rq_map_sg can safely extend the last entry of a scatter list.

blk_rq_map_sg must extend the last entry of a scatter list only for a
request that got through bio_copy_user_iov. This patches introduces
new REQ_COPY_USER flag.

Signed-off-by: FUJITA Tomonori 
Cc: Tejun Heo 
Cc: Mike Christie 
Cc: James Bottomley 
Signed-off-by: Jens Axboe

[SCSI] export command allocation and freeing functions independently of the host

2008-04-07T17:18:57+00:00

This is needed by things like USB storage that want to set up static
commands for later use at start of day.

Signed-off-by: James Bottomley

[SCSI] consolidate command allocation in a single place

2008-04-07T17:17:30+00:00

Since the way we allocate commands with a separate sense buffer is
getting complicated, we should isolate setup and teardown to a single
routine so that if it gets even more complex, there's only one place
in the code that needs to be altered.

Signed-off-by: James Bottomley

scsi: fix sense_slab/bio swapping livelock

2008-04-06T23:10:08+00:00

Since 2.6.25-rc7, I've been seeing an occasional livelock on one x86_64
machine, copying kernel trees to tmpfs, paging out to swap.

Signature: 6000 pages under writeback but never getting written; most
tasks of interest trying to reclaim, but each get_swap_bio waiting for a
bio in mempool_alloc's io_schedule_timeout(5*HZ); every five seconds an
atomic page allocation failure report from kblockd failing to allocate a
sense_buffer in __scsi_get_command.

__scsi_get_command has a (one item) free_list to protect against this,
but rc1's [SCSI] use dynamically allocated sense buffer
de25deb18016f66dcdede165d07654559bb332bc upset that slightly.  When it
fails to allocate from the separate sense_slab, instead of giving up, it
must fall back to the command free_list, which is sure to have a
sense_buffer attached.

Either my earlier -rc testing missed this, or there's some recent
contributory factor.  One very significant factor is SLUB, which merges
slab caches when it can, and on 64-bit happens to merge both bio cache
and sense_slab cache into kmalloc's 128-byte cache: so that under this
swapping load, bios above are liable to gobble up all the slots needed
for scsi_cmnd sense_buffers below.

That's disturbing behaviour, and I tried a few things to fix it.  Adding
a no-op constructor to the sense_slab inhibits SLUB from merging it, and
stops all the allocation failures I was seeing; but it's rather a hack,
and perhaps in different configurations we have other caches on the
swapout path which are ill-merged.

Another alternative is to revert the separate sense_slab, using
cache-line-aligned sense_buffer allocated beyond scsi_cmnd from the one
kmem_cache; but that might waste more memory, and is only a way of
diverting around the known problem.

While I don't like seeing the allocation failures, and hate the idea of
all those bios piled up above a scsi host working one by one, it does
seem to emerge fairly soon with the livelock fix.  So lacking better
ideas, stick with that one clear fix for now.

Signed-off-by: Hugh Dickins 
Cc: James Bottomley 
Cc: Andrew Morton 
Cc: FUJITA Tomonori 
Cc: Jens Axboe 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: Peter Zijlstra 
Cc: Rafael J. Wysocki 
Signed-off-by: Linus Torvalds

scsi: missing add of padded bytes to io completion byte count

2008-03-04T19:24:05+00:00

Original patch from Tejun Heo  but should use ->extra_len
and not ->data_len, as we would then overshoot the original request size.

Signed-off-by: Jens Axboe