From: 	Alan Stern <stern@rowland.harvard.edu>

This patch (as559b) adds a new routine, scsi_unprep_request, which
gets called every place a request is requeued.  (That includes
scsi_queue_insert as well as scsi_requeue_command.)  It also changes
scsi_kill_requests to make it call __scsi_done with result equal to
DID_NO_CONNECT << 16.  (I'm not sure if it's necessary to call
scsi_init_cmd_errh here; maybe you can check on that.)  Finally, the
patch changes the return value from scsi_end_request, to avoid
returning a stale pointer in the case where the request was requeued.
Fortunately the return value is used in only place, and the change
actually simplified it.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>

Rejections fixed up and
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

  If a filesystem, while writing out data, decides that it is good
to issue a cache flush on a SCSI drive (or other 'sd' device), it will
call blkdev_issue_flush which calls ->issue_flush_fn which is
scsi_issue_flush_fn.
This calls sd_issue_flush which calls sd_sync_cache, which calls
scsi_execute_request.
This will (as sshdr != NULL) call
    kmalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL)

If memory is tight, the presence of GFP_KERNEL may cause write
requests to be sent to some filesystem to free up memory, however if
that filesystem is waiting for the issue_flush_fn to complete, you
could get a deadlock.

I wonder if it might be more appropriate to use GFP_NOIO as in the
following patch.

I wonder if it might be even more appropriate to cope better with a
kmalloc failure, especially as in this use, sd_sync_cache only will
use the sense information to print out a more informative error
message.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

scsi_io_completion() can be a bit noisy about certain conditions.
Previously this wasn't a problem for internally generated commands,
since they never hit it.  However, since we do all SCSI commands via
bios, now they do.  user CD testers like magicdev are now getting not
ready messages every time they touch the CD to see if there's anything
in it.

Fix this by making all scsi_execute commands REQ_QUIET and making
scsi_finish_io() not say anything for REQ_QUIET.
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

The new bio code was incorrectly converted from stack allocated to
kmalloc'd buffer handling.  There are two places where it incorrectly
uses sizeof(*sense) to get the size of the sense buffer.  This
actually produces one, so no sense data was ever getting back, causing
failure in things like disk spin up.
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

Older gcc's require variable definitions at the beginning of a block.
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

This one removes struct scsi_request entirely from sd.  In the process,
I noticed we have no callers of scsi_wait_req who don't immediately
normalise the sense, so I updated the API to make it take a struct
scsi_sense_hdr instead of simply a big sense buffer.
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

This one's slightly more difficult.  The transport class uses
REQ_FAILFAST, so another interface (scsi_execute) had to be invented to
take the extra flag.  Also, the sense functions are shifted around to
allow spi_execute to place data directly into a struct scsi_sense_hdr.
With this change, there's probably a lot of unnecessary sense buffer
allocation going on which we can fix later.
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

After this, we just have some drivers, all the ULDs and the SPI
transport class using scsi_wait_req().
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

Original From: Mike Christie <michaelc@cs.wisc.edu>

Add scsi_execute_req() as a replacement for scsi_wait_req()

Fixed up various pieces (added REQ_SPECIAL and caught req use after
free)
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

Here's the proof of concept for this one.  It converts scsi_wait_req to
do correct REQ_BLOCK_PC submission (and works nicely in my setup).

The final goal should be to eliminate struct scsi_request, but that
can't be done until the character submission paths of sg and st are also
modified.

There's some loss of functionality to this: retries are no longer
controllable (except by setting REQ_FASTFAIL) and the wait_req API needs
to be altered, but it looks very nice.
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

Migrate the current SCSI host state model to a model like SCSI
device is using.
Signed-off-by: NMike Anderson <andmike@us.ibm.com>

Rejections fixed up and
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

scsi_init_io calls scsi_alloc_sgtable and then calls blk_rq_map_sg
to initialize the scatterlist structure.  blk_rq_map_sg() already
memset the structure for every new segment.  That makes the memset
in scsi_alloc_sgtable unnecessary.

Patch to delete the extra memset in scsi_alloc_sgtable.  Tested on
a x86_64 machine.  Looks stable to me.
Signed-off-by: NKen Chen <kenneth.w.chen@intel.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

The check in

627  		BUG_ON(index > SG_MEMPOOL_NR);

with SG_MEMPOOL_NR defined in

32   	#define SG_MEMPOOL_NR		(sizeof(scsi_sg_pools)/sizeof(struct scsi_host_sg_pool))

was not sufficient.

sgp, set in

629  		sgp = scsi_sg_pools + index;

is dereferenced in

630  		mempool_free(sgl, sgp->pool);
Signed-off-by: NZaur Kambarov <zkambarov@coverity.com>
Cc: <linux-scsi@vger.kernel.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We never look at it except for the old megaraid driver that abuses it
for sending internal commands.  That usage can be fixed easily because
those internal commands are single-threaded by a mutex and we can easily
use a completion there.
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

never checked anywhere
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

Never used for anything but printing it out in debug routines.
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

Another rollup of patches which give various symbols static scope
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

scsi_queue_insert() has four callers.  Three callers call with
timer disabled and one (the second invocation in
scsi_dispatch_cmd()) calls with timer activated.
scsi_queue_insert() used to always call scsi_delete_timer()
and ignore the return value.  This results in race with timer
expiration.  Remove scsi_delete_timer() call from
scsi_queue_insert() and make the caller delete timer and check
the return value.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

scsi_queue_insert() used to use blk_insert_request() for requeueing
requests.  This depends on the unobvious behavior of
blk_insert_request() setting REQ_SPECIAL and REQ_SOFTBARRIER when
requeueing.  This patch makes scsi_queue_insert() use
blk_requeue_request().  As REQ_SPECIAL means special requests and
REQ_SOFTBARRIER is automatically handled by blk layer now, no flag
needs to be set.

Note that scsi_queue_insert() now calls scsi_run_queue() itself, and
the prototype of the function is added right above
scsi_queue_insert().  This is temporary, as later requeue path
consolidation patchset removes scsi_queue_insert().  By adding
temporary prototype, we can do away with unnecessarily moving
functions.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

scsi_requeue_request() used to use blk_insert_request() for requeueing
requests.  This depends on the unobvious behavior of
blk_insert_request() setting REQ_SPECIAL and REQ_SOFTBARRIER when
requeueing.  This patch makes scsi_queue_insert() use
blk_requeue_request().  As REQ_SPECIAL means special requests and
REQ_SOFTBARRIER is automatically handled by blk layer now, no flag
needs to be set.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

blk_insert_request() has a unobivous feature of requeuing a
request setting REQ_SPECIAL|REQ_SOFTBARRIER.  SCSI midlayer
was the only user and as previous patches removed the usage,
remove the feature from blk_insert_request().  Only special
requests should be queued with blk_insert_request().  All
requeueing should go through blk_requeue_request().
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

scsi_init_io() used to set REQ_SPECIAL when it fails sg
allocation before requeueing the request by returning
BLKPREP_DEFER.  REQ_SPECIAL is being updated to mean special
requests.  So, remove REQ_SPECIAL setting.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

scsi_cmnd->serial_number_at_timeout doesn't serve any purpose
anymore.  All serial_number == serial_number_at_timeout tests
are always true in abort callbacks.  Kill the field.  Also, as
->pid always equals ->serial_number and ->serial_number
doesn't have any special meaning anymore, update comments
above ->serial_number accordingly.  Once we remove all uses of
this field from all lldd's, this field should go.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

scsi_cmnd->internal_timeout field doesn't have any meaning
anymore.  Kill the field.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

scsi_cmnd->serial_number_at_timeout doesn't serve any purpose
anymore.  All serial_number == serial_number_at_timeout tests
are always true in abort callbacks.  Kill the field.  Also, as
->pid always equals ->serial_number and ->serial_number
doesn't have any special meaning anymore, update comments
above ->serial_number accordingly.  Once we remove all uses of
this field from all lldd's, this field should go.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

scsi_cmnd->internal_timeout field doesn't have any meaning
anymore.  Kill the field.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

The current problem seen is that the queue lock is actually in the
SCSI device structure, so when that structure is freed on device
release, we go boom if the queue tries to access the lock again.

The fix here is to move the lock from the scsi_device to the queue.
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!