use ioaccel2 path to submit I/O to physical drives in HBA mode
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NJoe Handzik <joseph.t.handzik@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

offload_enabled changes are deferred until after the
added/updated prints occur, so the values are incorrect.

defer printing SSD Smart Path Enabled status information until the
information is correct
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

clean up command submission
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NWebb Scales <webbnh@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

allow the controller firmware to queue up commands when the ioaccel device
queue is full.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

add error handling for failure when registering with SCSI subsystem.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

Factor out hpsa_cmd_init from cmd_alloc().  We also need
this for resubmitting commands down the default RAID path
when they have returned from the ioaccel paths with errors.

In particular, reinitialize the cmd_type and busaddr fields as these
will not be correct for submitting down the RAID stack path
after ioaccel command completion.

This saves time when submitting commands.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

make function names more consistent and meaningful
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

expose a detected lockup via sysfs
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

In hba mode, we could get sense data in descriptor format so
we need to handle that.

It's possible for CommandStatus to have value 0x0D
"TMF Function Status", which we should handle.  We will get
this from a P1224 when aborting a non-existent tag, for
example.  The "ScsiStatus" field of the errinfo field
will contain the TMF function status value.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

make tracking of outstanding commands more robust
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

Do not send aborts to logical devices that do not support aborts

Instead of relying on what the Smart Array claims for supporting logical
drives, simply try an abort and see how it responds at device discovery
time.  This way devices that do support aborts (e.g. MSA2000) can work
and we do not waste time trying to send aborts to logical drives that do
not support them (important for high IOPS devices.)

While rescanning devices only test whether devices support aborts
the first time we encounter a device rather than every time.

Some Smart Arrays required aborts to be sent with tags in
the wrong endian byte order.  To avoid having to know about
this, we would send two aborts with tags with each endian order.
On high IOPS devices, this turns out to be not such a hot idea.
So we now have a list of the devices that got the tag backwards,
and we only send it one way.

If all available commands are outstanding and the abort handler
is invoked, the abort handler may not be able to allocate a command
and may busy-wait excessivly.  Reserve a small number of commands
for the abort handler and limit the number of concurrent abort
requests to the number of reserved commands.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

Allow driver initiated commands to have a timeout.  It does not
yet try to do anything with timeouts on such commands.

We are sending a reset in order to get rid of a command we want to abort.
If we make it return on the same reply queue as the command we want to abort,
the completion of the aborted command will not race with the completion of
the reset command.

Rename hpsa_scsi_do_simple_cmd_core() to hpsa_scsi_do_simple_cmd(), since
this function is the interface for issuing commands to the controller and
not the "core" of that implementation.  Add a parameter to it which allows
the caller to specify the reply queue to be used.  Modify existing callers
to specify the default reply queue.

Rename __hpsa_scsi_do_simple_cmd_core() to hpsa_scsi_do_simple_cmd_core(),
since this routine is the "core" implementation of the "do simple command"
function and there is no longer any other function with a similar name.
Modify the existing callers of this routine (other than
hpsa_scsi_do_simple_cmd()) to instead call hpsa_scsi_do_simple_cmd(), since
it will now accept the reply_queue paramenter, and it provides a controller
lock-up check.  (Also, tweak two related message strings to make them
distinct from each other.)

Submitting a command to a locked up controller always results in a timeout,
so check for controller lock-up before submitting.

This is to enable fixing a race between command completions and
abort completions on different reply queues in a subsequent patch.
We want to be able to specify which reply queue an abort completion
should occur on so that it cannot race the completion of the command
it is trying to abort.

The following race was possible in theory:

  1. Abort command is sent to hardware.
  2. Command to be aborted simultaneously completes on another
     reply queue.
  3. Hardware receives abort command, decides command has already
     completed and indicates this to the driver via another different
     reply queue.
  4. driver processes abort completion finds that the hardware does not know
     about the command, concludes that therefore the command cannot complete,
     returns SUCCESS indicating to the mid-layer that the scsi_cmnd may be
     re-used.
  5. Command from step 2 is processed and completed back to scsi mid
     layer (after we already promised that would never happen.)

Fix by forcing aborts to complete on the same reply queue as the command
they are aborting.

Piggybacking device rescanning functionality onto the lockup
detection thread is not a good idea because if the controller
locks up during device rescanning, then the thread could get
stuck, then the lockup isn't detected.  Use separate work
queues for device rescanning and lockup detection.

Detect controller lockup in abort handler.

After a lockup is detected, return DO_NO_CONNECT which results in immediate
termination of commands rather than DID_ERR which results in retries.

Modify detect_controller_lockup() to return the result, to remove the need for
a separate check.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Signed-off-by: NWebb Scales <webbnh@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

We had a mix of formats used for specifying controller, bus, target,
and lun address of devices.

change to the format used by the scsi midlayer and upper layer (2:3:0:0)
so you can easily follow the information from hpsa to scsi midlayer
to sd upper layer.

Also add this information:
- product ID
- vendor ID
- RAID level
- SSD Smath Path capable and enabled
- exposure level (sg-only)

Example:
hpsa 0000:04:00.0: added scsi 2:0:0:0: Direct-Access     HP LOGICAL VOLUME   RAID-0 SSDSmartPathCap+ En+ Exp=4
scsi 2:0:0:0: Direct-Access     HP       LOGICAL VOLUME   10.0 PQ: 0 ANSI: 5
sd 2:0:0:0: [sdr] 12501713072 512-byte logical blocks: (6.40 TB/5.82 TiB)
sd 2:0:0:0: [sdr] 4096-byte physical blocks
sd 2:0:0:0: [sdr] Attached SCSI disk
sd 2:0:0:0: Attached scsi generic sg20 type 0
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

Cache the ioaccel handle so that when we need to abort commands sent
down the ioaccel2 path, we can look up the LUN ID in h->dev[] instead of
having to do I/O to the controller.

Add a field to elements in h->dev[] to keep track of how the device is exposed
to the SCSI mid layer: Not at all, without an upper level driver
(no_uld_attach) or normally exposed.

Since masked physical devices are now present in h->dev[] array
it would be perfectly possible to do

	echo scsi add-single-device 2 2 0 0 > /proc/scsi/scsi

and bring them online.  This was previously not allowed for masked
physical devices.

Ensure that the mapping of physical disks to logical drives gets updated in a
consistent way when a RAID migration occurs and is not touched until updates
to it are complete.

now instead of doing CISS_REPORT_PHYSICAL to get the LUNID for
the physical disk in hpsa_get_pdisk_of_ioaccel2(), just get
it out of h->dev[] where we already have it cached.

do not touch phys_disk[] for ioaccel enabled logical drives during rescan
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NKevin Barnett <kevin.barnett@pmcs.com>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NHannes Reinecke <hare@Suse.de>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

The hpsa driver touches the hardware before checking the pci-id table.
This way, especially in kdump, it may confuse the proper driver (cciss).
Signed-off-by: NTomas Henzl <thenzl@redhat.com>
Acked-by: NDon Brace <Don.Brace@pmcs.com>
Signed-off-by: NJames Bottomley <JBottomley@Odin.com>

This may be OK in archs with contiguous CPU numbers and without
hotplug CPUs, but it sets a terrible example.

And open-coding it like drivers/scsi/hpsa.c is just weird.

BTRFS has a weird comparison with num_online_cpus() too, but since
BTRFS just screwed up my test machines' root partition, I'm not
touching it :)
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Reported-by: NOleg Drokin <green@linuxhacker.ru>

Correct compiler warning introduced by hpsa-add-local-workqueue patch
6636e7f4 hpsa: Use local workqueues
instead of system workqueues
Suggested-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NWebb Scales <webbnh@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

Suggested-by: NTomas Henzl <thenzl@redhat.com>
Reviewed-by: NWebb Scales <webbnh@hp.com>
Reviewed-by: NKevin Barnett <Kevin.Barnett@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Add in P840ar model name for gen9
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Add in gen9 controller model names
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Detect failues when attempting to change controller to use simple
or performant transport modes (mode change ack) rather than just
proceeding ahead after timeouts.

Return values are added to:
	hpsa_put_ctlr_into_performant_mode
	hpsa_wait_for_mode_change_ack
and all their callers check/propagate the result.

More consistency in printing errors and whether
dev_err is used.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Shorten the wait for the CISS configuration table doorbell mode
change acknowledgment from 300-600 s to 20 s, which is the value
specified in the CISS specification that should be honored by
all controllers.

Wait using interruptible msleep() rather than uninterruptible
usleep_range(), which triggers rt_sched timeout errors if the
wait is long.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Hoist the conditional out of do_not_scan_if_controller_locked_up() and
place it in the caller (this improves the code structure, making it
more consistent with other uses and enabling tail-call optimization);
rename the function to hpsa_scan_complete(), and use it at the end of
hpsa_scan_start() as well.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NWebb Scales <webbnh@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Move the code which sets up the SG descriptor out of hpsa_scatter_gather()
and into a subroutine where it can be reused (in the next patch).  The Ext
field is now assigned unconditionally: this makes the refactor much simpler,
but more importantly it removes a conditional operation from inside the
loop.  The case for which the conditional formerly tested is now executed
(unconditionally) after the loop is exited.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NWebb Scales <webbnh@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Performance tweak, avoid unnecessary function calls.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Printing the address of the command pointer is of little value, change
to print the CDB.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

There's no reason for it to be a void *, it should be a struct scsi_cmnd *
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Returning failed from the device reset handler will get the device
kicked offline, which is fine if the controller is locked up anyhow.

Cannot abort a command from a failed controller.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NJustin Lindley <justin.lindley@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Command allocation is the thing that takes the longest in the main i/o
path, so check for controller lockup immediately after this to prevent
submitting commands to locked up controller as much as possible.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

In the code that translates logical drive LBAs to physical
drive LBAs if we overflow the raid map disk data array we
will get the wrong answers.  We do not expect that to happen,
but best to be on the safe side and guard against it anyway.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Acking controller events on controllers that do not support
it can cause such controllers to lock up.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NJoe Handzik <joseph.t.handzik@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

In set_encrypt_ioaccel2() and in hpsa_scsi_ioaccel_raid_map
there were BUG_ONs that looked like this:

	BUG_ON(!(dev->offload_config && dev->offload_enabled));

But, In hpsa_ack_ctlr_events() we have this,

	/* Stop sending new RAID offload reqs via the IO accelerator */
	scsi_block_requests(h->scsi_host);
	for (i = 0; i < h->ndevices; i++)
		h->dev[i]->offload_enabled = 0;
	hpsa_drain_accel_commands(h);

So, we set offload_enabled = 0 for all drives, then do this
drain_accel_commands, so that means accel commands could still
be in flight, ie. perhaps having just been submitted into
hpsa_scsi_ioaccel_raid_map concurrent with ->offload_enabled
having just been set to zero.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Performance enhancement. Remove spin_locks from the driver.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Empirically, this improves performance slightly (~2% max IOPS) by
allowing cmd_alloc to remember where it left off searching for
free commands between calls instead of always starting its search
at command 0.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

This means changing the allocator to reference count commands.
The reference count is now the authoritative indicator of whether a
command is allocated or not.  The h->cmd_pool_bits bitmap is now
only a heuristic hint to speed up the allocation process, it is no
longer the authoritative record of allocated commands.

Since we changed the command allocator to use reference counting
as the authoritative indicator of whether a command is allocated,
fail_all_outstanding_cmds needs to use the reference count not
h->cmd_pool_bits for this purpose.

Fix hpsa_drain_accel_commands to use the reference count as the
authoritative indicator of whether a command is allocated instead of
the h->cmd_pool_bits bitmap.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

When using the ioaccel submission methods, requests destined for RAID volumes
are sometimes diverted to physical devices.  The OS has no or limited
knowledge of these physical devices, so it is up to the driver to avoid
pushing the device too hard.  It is better to honor the physical device queue
limit rather than making the device spew zillions of TASK SET FULL responses.

This is so that hpsa based devices support /sys/block/sdNN/device/queue_type
of simple, which lets the SCSI midlayer automatically adjust the queue_depth
based on TASK SET FULL and GOOD status.

Adjust the queue depth for a new device after it is created based on the
maximum queue depths of the physical devices that constitute the
device. This drops the maximum queue depth from .can_queue of 1024 to
something like 174 for single-drive RAID-0, 348 for two-drive RAID-1, etc.
It also adjusts for the ratio of data to parity drives.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NWebb Scales <webbnh@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Instead of kicking the commands all the way back to the mid
layer, use a work queue.  This enables having a mechanism for
the driver to be able to resubmit the commands down the "normal"
raid path without turning off the ioaccel feature entirely
whenever an error is encountered on the ioaccel path, and
prevent excessive rescanning of devices.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Factor out the bottom part of the queuecommand function
which is the part that builds commands for submitting down
the "normal' RAID stack path of a Smart Array.

Need to factor this out to improve how commands that
were initially sent down one of the "ioaccellerated"
paths but which have some sort of error condition are
retried down the "normal" path.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

The original reasoning behind doing this was faulty.  An error
of some sort would be encountered, accelerated i/o would be
disabled for that logical drive, the command would be kicked
back out to the SCSI midlayer for a retry, and since i/o accelerator
mode was disabled, it would get retried down the RAID path.
However, something needs to turn ioaccellerator mode back on,
and this rescan request was what did that.  However, it was racy,
and extremely bad for performance to rescan all devices, so,
don't do that.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

By not doing maintaining a list of queued commands, we can eliminate some spin
locking in the main i/o path and gain significant improvement in IOPS.  Remove
the queuing code and the code that calls it; remove now-unused interrupt code;
remove DIRECT_LOOKUP_BIT.

Now that the passthru commands share the same command pool as
the main i/o path, and the total size of the pool is less than
or equal to the number of commands that will fit in the hardware
fifo, there is no need to check to see if we are exceeding the
hardware fifo's depth.
Reviewed-by: NScott Teel <scott.teel@pmcs.com>
Reviewed-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NDon Brace <don.brace@pmcs.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>