linux-toradex.git/drivers/block/aoe/aoe.h, branch v3.4.2

aoe: allocate unused request_queue for sysfs

2009-09-09T12:10:18+00:00

Andy Whitcroft reported an oops in aoe triggered by use of an
incorrectly initialised request_queue object:

  [ 2645.959090] kobject '' (ffff880059ca22c0): tried to add
		an uninitialized object, something is seriously wrong.
  [ 2645.959104] Pid: 6, comm: events/0 Not tainted 2.6.31-5-generic #24-Ubuntu
  [ 2645.959107] Call Trace:
  [ 2645.959139] [] kobject_add+0x5f/0x70
  [ 2645.959151] [] blk_register_queue+0x8b/0xf0
  [ 2645.959155] [] add_disk+0x8f/0x160
  [ 2645.959161] [] aoeblk_gdalloc+0x164/0x1c0 [aoe]

The request queue of an aoe device is not used but can be allocated in
code that does not sleep.

Bruno bisected this regression down to

  cd43e26f071524647e660706b784ebcbefbd2e44

  block: Expose stacked device queues in sysfs

"This seems to generate /sys/block/$device/queue and its contents for
 everyone who is using queues, not just for those queues that have a
 non-NULL queue->request_fn."

Addresses http://bugs.launchpad.net/bugs/410198
Addresses http://bugzilla.kernel.org/show_bug.cgi?id=13942

Note that embedding a queue inside another object has always been
an illegal construct, since the queues are reference counted and
must persist until the last reference is dropped. So aoe was
always buggy in this respect (Jens).

Signed-off-by: Ed Cashin 
Cc: Andy Whitcroft 
Cc: "Rafael J. Wysocki" 
Cc: Bruno Premont 
Cc: Martin K. Petersen 
Cc: Andrew Morton 
Signed-off-by: Jens Axboe

aoe: ignore vendor extension AoE responses

2009-02-18T23:37:53+00:00

The Welland ME-747K-SI AoE target generates unsolicited AoE responses that
are marked as vendor extensions.  Instead of ignoring these packets, the
aoe driver was generating kernel messages for each unrecognized response
received.  This patch corrects the behavior.

Signed-off-by: Ed Cashin 
Reported-by: 
Tested-by: 
Cc: 
Cc: Alex Buell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: remove private mac address format function

2008-11-25T08:40:37+00:00

Add %pm to omit the colons when printing a mac address.

Signed-off-by: Harvey Harrison 
Signed-off-by: David S. Miller

aoe: Use SKB interfaces for list management instead of home-grown stuff.

2008-09-22T05:36:49+00:00

Signed-off-by: David S. Miller

remove aoedev_isbusy()

2008-04-29T15:06:24+00:00

Remove the no longer used aoedev_isbusy().

Signed-off-by: Adrian Bunk 
Cc: "Ed L. Cashin" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: update copyright date

2008-02-08T17:22:32+00:00

Update the year in the copyright notices.

Signed-off-by: Ed L. Cashin 
Cc: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: dynamically allocate a capped number of skbs when necessary

2008-02-08T17:22:32+00:00

What this Patch Does

  Even before this recent series of 12 patches to 2.6.22-rc4, the aoe
  driver was reusing a small set of skbs that were allocated once and
  were only used for outbound AoE commands.

  The network layer cannot be allowed to put_page on the data that is
  still associated with a bio we haven't returned to the block layer,
  so the aoe driver (even before the patch under discussion) is still
  the owner of skbs that have been handed to the network layer for
  transmission.  We need to keep track of these skbs so that we can
  free them, but by tracking them, we can also easily re-use them.

  The new patch was a response to the behavior of certain network
  drivers.  We cannot reuse an skb that the network driver still has
  in its transmit ring.  Network drivers can defer transmit ring
  cleanup and then use the state in the skb to determine how many data
  segments to clean up in its transmit ring.  The tg3 driver is one
  driver that behaves in this way.

  When the network driver defers cleanup of its transmit ring, the aoe
  driver can find itself in a situation where it would like to send an
  AoE command, and the AoE target is ready for more work, but the
  network driver still has all of the pre-allocated skbs.  In that
  case, the new patch just calls alloc_skb, as you'd expect.

  We don't want to get carried away, though.  We try not to do
  excessive allocation in the write path, so we cap the number of skbs
  we dynamically allocate.

  Probably calling it a "dynamic pool" is misleading.  We were already
  trying to use a small fixed-size set of pre-allocated skbs before
  this patch, and this patch just provides a little headroom (with a
  ceiling, though) to accomodate network drivers that hang onto skbs,
  by allocating when needed.  The d->skbpool_hd list of allocated skbs
  is necessary so that we can free them later.

  We didn't notice the need for this headroom until AoE targets got
  fast enough.

Alternatives

  If the network layer never did a put_page on the pages in the bio's
  we get from the block layer, then it would be possible for us to
  hand skbs to the network layer and forget about them, allowing the
  network layer to free skbs itself (and thereby calling our own
  skb->destructor callback function if we needed that).  In that case
  we could get rid of the pre-allocated skbs and also the
  d->skbpool_hd, instead just calling alloc_skb every time we wanted
  to transmit a packet.  The slab allocator would effectively maintain
  the list of skbs.

  Besides a loss of CPU cache locality, the main concern with that
  approach the danger that it would increase the likelihood of
  deadlock when VM is trying to free pages by writing dirty data from
  the page cache through the aoe driver out to persistent storage on
  an AoE device.  Right now we have a situation where we have
  pre-allocation that corresponds to how much we use, which seems
  ideal.

  Of course, there's still the separate issue of receiving the packets
  that tell us that a write has successfully completed on the AoE
  target.  When memory is low and VM is using AoE to flush dirty data
  to free up pages, it would be perfect if there were a way for us to
  register a fast callback that could recognize write command
  completion responses.  But I don't think the current problems with
  the receive side of the situation are a justification for
  exacerbating the problem on the transmit side.

Signed-off-by: Ed L. Cashin 
Cc: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: user can ask driver to forget previously detected devices

2008-02-08T17:22:31+00:00

When an AoE device is detected, the kernel is informed, and a new block device
is created.  If the device is unused, the block device corresponding to remote
device that is no longer available may be removed from the system by telling
the aoe driver to "flush" its list of devices.

Without this patch, software like GPFS and LVM may attempt to read from AoE
devices that were discovered earlier but are no longer present, blocking until
the I/O attempt times out.

Signed-off-by: Ed L. Cashin 
Cc: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: mac_addr: avoid 64-bit arch compiler warnings

2008-02-08T17:22:31+00:00

By returning unsigned long long, mac_addr does not generate compiler warnings
on 64-bit architectures.

Signed-off-by: Ed L. Cashin 
Cc: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

aoe: handle multiple network paths to AoE device

2008-02-08T17:22:31+00:00

A remote AoE device is something can process ATA commands and is identified by
an AoE shelf number and an AoE slot number.  Such a device might have more
than one network interface, and it might be reachable by more than one local
network interface.  This patch tracks the available network paths available to
each AoE device, allowing them to be used more efficiently.

Andrew Morton asked about the call to msleep_interruptible in the revalidate
function.  Yes, if a signal is pending, then msleep_interruptible will not
return 0.  That means we will not loop but will call aoenet_xmit with a NULL
skb, which is a noop.  If the system is too low on memory or the aoe driver is
too low on frames, then the user can hit control-C to interrupt the attempt to
do a revalidate.  I have added a comment to the code summarizing that.

Andrew Morton asked whether the allocation performed inside addtgt could use a
more relaxed allocation like GFP_KERNEL, but addtgt is called when the aoedev
lock has been locked with spin_lock_irqsave.  It would be nice to allocate the
memory under fewer restrictions, but targets are only added when the device is
being discovered, and if the target can't be added right now, we can try again
in a minute when then next AoE config query broadcast goes out.

Andrew Morton pointed out that the "too many targets" message could be printed
for failing GFP_ATOMIC allocations.  The last patch in this series makes the
messages more specific.

Signed-off-by: Ed L. Cashin 
Cc: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds