The block driver uses scatter-gather lists with sg[0] being the
request information (struct virtio_blk_outhdr) with the type, sector
and inbuf id.  The next N sg entries are the bio itself, then the last
sg is the status byte.  Whether the N entries are in or out depends on
whether it's a read or a write.

We accept the normal (SCSI) ioctls: they get handed through to the other
side which can then handle it or reply that it's unsupported.  It's
not clear that this actually works in general, since I don't know
if blk_pc_request() requests have an accurate rq_data_dir().

Although we try to reply -ENOTTY on unsupported commands, ioctl(fd,
CDROMEJECT) returns success to userspace.  This needs a separate
patch.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jens Axboe <jens.axboe@oracle.com>

This option is already in arch/um/Kconfig.char

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Jeff Dike <jdike@addtoit.com>

Signed-off-by: Adrian Bunk <bunk@kernel.org>

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Introduce CONFIG_CHECK_SIGNATURE to control inclusion of check_signature()
and avoid problems on platforms that don't have readb().

Let the few legacy (ISA || PCI || X86) drivers that need check_signature()
select CONFIG_CHECK_SIGNATURE.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (edited MACINTOSH_DRIVERS per Geert Uytterhoeven's remark)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The block device frontend driver allows the kernel to access block
devices exported exported by a virtual machine containing a physical
block device driver.

Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Greg KH <greg@kroah.com>
Cc: Jens Axboe <axboe@kernel.dk>

Tested on Xilinx Virtex ppc405, Katmai 440SPe, and Microblaze

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Stefan Roese <sr@denx.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: John William <jwilliams@itee.uq.edu.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git.kernel.dk/data/git/linux-2.6-block:
  splice: direct splicing updates ppos twice
  more ACSI removal
  umem: Fix match of pci_ids in umem driver
  umem: Remove references to dead CONFIG_MM_MAP_MEMORY variable
  remove the documentation for the legacy CDROM drivers

* 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6: (26 commits)
  [SPARC64]: Fix UP build.
  [SPARC64]: dr-cpu unconfigure support.
  [SERIAL]: Fix console write locking in sparc drivers.
  [SPARC64]: Give more accurate errors in dr_cpu_configure().
  [SPARC64]: Clear cpu_{core,sibling}_map[] in smp_fill_in_sib_core_maps()
  [SPARC64]: Fix leak when DR added cpu does not bootup.
  [SPARC64]: Add ->set_affinity IRQ handlers.
  [SPARC64]: Process dr-cpu events in a kthread instead of workqueue.
  [SPARC64]: More sensible udelay implementation.
  [SPARC64]: SMP build fixes.
  [SPARC64]: mdesc.c needs linux/mm.h
  [SPARC64]: Fix build regressions added by dr-cpu changes.
  [SPARC64]: Unconditionally register vio_bus_type.
  [SPARC64]: Initial LDOM cpu hotplug support.
  [SPARC64]: Fix setting of variables in LDOM guest.
  [SPARC64]: Fix MD property lifetime bugs.
  [SPARC64]: Abstract out mdesc accesses for better MD update handling.
  [SPARC64]: Use more mearningful names for IRQ registry.
  [SPARC64]: Initial domain-services driver.
  [SPARC64]: Export powerd facilities for external entities.
  ...