disk->part[] is protected by its matching bdev's lock.  However,
non-critical accesses like collecting stats and printing out sysfs and
proc information used to be performed without any locking.  As
partitions can come and go dynamically, partitions can go away
underneath those non-critical accesses.  As some of those accesses are
writes, this theoretically can lead to silent corruption.

This patch fixes the race by using RCU for the partition array and dev
reference counter to hold partitions.

* Rename disk->part[] to disk->__part[] to make sure no one outside
  genhd layer proper accesses it directly.

* Use RCU for disk->__part[] dereferencing.

* Implement disk_{get|put}_part() which can be used to get and put
  partitions from gendisk respectively.

* Iterators are implemented to help iterate through all partitions
  safely.

* Functions which require RCU readlock are marked with _rcu suffix.

* Use disk_put_part() in __blkdev_put() instead of directly putting
  the contained kobject.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

This patch makes the following misc updates in preparation for
disk->part dereference fix and extended block devt support.

* implment part_to_disk()

* fix comment about gendisk->part indexing

* rename get_part() to disk_map_sector()

* don't use n which is always zero while printing disk information in
  diskstats_show()
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

get_part() is fairly expensive, as it O(N) loops over partitions
to find the right one. In lots of normal IO paths we end up looking
up the partition twice, to make matters even worse. Change the
stat add code to accept a passed in partition instead.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Cc: Ed L. Cashin <ecashin@coraid.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Update the year in the copyright notices.
Signed-off-by: NEd L. Cashin <ecashin@coraid.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Andrew Morton pointed out that the "too many targets" message in patch 2 could
be printed for failing GFP_ATOMIC allocations.  This patch makes the messages
more specific.
Signed-off-by: NEd L. Cashin <ecashin@coraid.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The aoedev aoeminor member doesn't need a long format.
Signed-off-by: NEd L. Cashin <ecashin@coraid.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

An AoE target provides an estimate of the number of outstanding commands that
the AoE initiator can send before getting a response.  The aoe_maxout
parameter provides a way to set an even lower limit.  It will not allow a user
to use more outstanding commands than the target permits.  If a user discovers
a problem with a large setting, this parameter provides a way for us to work
with them to debug the problem.  We expect to improve the dynamic window
sizing algorithm and drop this parameter.  For the time being, it is a
debugging aid.
Signed-off-by: NEd L. Cashin <ecashin@coraid.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

An aoe driver user who had about 70 AoE targets found that he was hitting a
BUG in sysfs_create_file because the aoe driver was trying to tell the kernel
about an AoE device more than once.  Each AoE device was reachable by several
local network interfaces, and multiple ATA device indentify responses were
returning from that single device.

This patch eliminates a race condition so that aoe always informs the block
layer of a new AoE device once in the presence of multiple incoming ATA device
identify responses.
Signed-off-by: NEd L. Cashin <ecashin@coraid.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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: NEd L. Cashin <ecashin@coraid.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

By returning unsigned long long, mac_addr does not generate compiler warnings
on 64-bit architectures.
Signed-off-by: NEd L. Cashin <ecashin@coraid.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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: NEd L. Cashin <ecashin@coraid.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Updates the enhanced partition statistics in ATA over Ethernet driver
(not tested).
Signed-off-by: NJerome Marchand <jmarchan@redhat.com>

We can just use skb_mac_header now, and we don't need a wrapper function to
perform the cast.  Instead of requiring the reader to check aoe.h to look
up what an aoe_hdr function does, I'd rather do without it.
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch makes most of the generic device layer network
namespace safe.  This patch makes dev_base_head a
network namespace variable, and then it picks up
a few associated variables.  The functions:
dev_getbyhwaddr
dev_getfirsthwbytype
dev_get_by_flags
dev_get_by_name
__dev_get_by_name
dev_get_by_index
__dev_get_by_index
dev_ioctl
dev_ethtool
dev_load
wireless_process_ioctl

were modified to take a network namespace argument, and
deal with it.

vlan_ioctl_set and brioctl_set were modified so their
hooks will receive a network namespace argument.

So basically anthing in the core of the network stack that was
affected to by the change of dev_base was modified to handle
multiple network namespaces.  The rest of the network stack was
simply modified to explicitly use &init_net the initial network
namespace.  This can be fixed when those components of the network
stack are modified to handle multiple network namespaces.

For now the ifindex generator is left global.

Fundametally ifindex numbers are per namespace, or else
we will have corner case problems with migration when
we get that far.

At the same time there are assumptions in the network stack
that the ifindex of a network device won't change.  Making
the ifindex number global seems a good compromise until
the network stack can cope with ifindex changes when
you change namespaces, and the like.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As bi_end_io is only called once when the reqeust is complete,
the 'size' argument is now redundant.  Remove it.

Now there is no need for bio_endio to subtract the size completed
from bi_size.  So don't do that either.

While we are at it, change bi_end_io to return void.
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Cleanup of dev_base list use, with the aim to simplify making device
list per-namespace. In almost every occasion, use of dev_base variable
and dev->next pointer could be easily replaced by for_each_netdev
loop. A few most complicated places were converted to using
first_netdev()/next_netdev().
Signed-off-by: NPavel Emelianov <xemul@openvz.org>
Acked-by: NKirill Korotaev <dev@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For the common, open coded 'skb->nh.raw = skb->data' operation, so that we can
later turn skb->nh.raw into a offset, reducing the size of struct sk_buff in
64bit land while possibly keeping it as a pointer on 32bit.

This one touches just the most simple case, next will handle the slightly more
"complex" cases.
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For the common, open coded 'skb->mac.raw = skb->data' operation, so that we can
later turn skb->mac.raw into a offset, reducing the size of struct sk_buff in
64bit land while possibly keeping it as a pointer on 32bit.

This one touches just the most simple case, next will handle the slightly more
"complex" cases.
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For consistency with other skb->mac.raw users.
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Based upon a report by Andrew Walrond.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix a bug that only appears when AoE goes over a network card that does not
support scatter-gather.  The headers in the linear part of the skb appeared
to be larger than they really were, resulting in data that was offset by 24
bytes.

This patch eliminates the offset data on cards that don't support
scatter-gather or have had scatter-gather turned off.  There remains an
unrelated issue that I'll address in a separate email.

Fixes bugzilla #7662
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Cc: <stable@kernel.org>
Cc: Greg KH <greg@kroah.com>
Cc: <boddingt@optusnet.com.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix up for make allyesconfig.
Signed-Off-By: NDavid Howells <dhowells@redhat.com>

This patch addresses the concern that the aoe driver should
not introduce unecessary conventions that must be learned by
the reader.  It reverts patch 6.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Instead of starting with bio->bi_io_vec, use the offset in bio->bi_idx.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

The aoe_deadsecs module parameter sets the number of seconds that
elapse before a nonresponsive AoE device is marked as dead.

This is runtime settable in sysfs or settable with a module load or
kernel boot parameter.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Avoid memory copy on writes.
(This patch follows patch 4.)
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Add a dynamic minimum timer for better retransmission behavior.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Add support for jumbo ethernet frames.
(This patch follows patch 5.)
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Use simple macros to clean up the printks.
(This patch is reverted by the 14th patch to follow.)
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Add support for jumbo ethernet frames.
(This patch depends on patch 7 to follow.)
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Avoid memory copy on writes.
(This patch depends on fixes in patch 9 to follow.)

Although skb->len should not be set when working with linear skbuffs,
the skb->tail pointer maintained by skb_put/skb_trim is not relevant
to what happens when the skb_fill_page_desc function is called.  This
issue was raised without comment in linux-kernel and netdev earlier
this month:

  http://thread.gmane.org/gmane.linux.kernel/446474/
  http://thread.gmane.org/gmane.linux.network/45444/

So until there is something analogous to skb_put that works for
zero-copy write skbuffs, we will do what the other callers of
skb_fill_page_desc are doing.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Update the copyright year to 2006.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

On an ATA error response, take the device down instead of
sending another ATA device identify command.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>

This patch is a bugfix that follows and depends on the
eight aoe driver patches sent January 19th.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Retransmit to the current network interface for an AoE device.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>

Increase the number of AoE packets per device that can be outstanding
at one time, increasing performance.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Allow the driver to recognize AoE devices that have changed size.
Devices not in use are updated automatically, and devices that are in
use are updated at user request.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Zero the data in new socket buffers to prevent leaking information.
Signed-off-by: N"Ed L. Cashin" <ecashin@coraid.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>