block/partitions: optimize memory allocation in check_partition()

Currently, sizeof(struct parsed_partitions) may be 64KB in 32bit arch, so
it is easy to trigger page allocation failure by check_partition,
especially in hotplug block device situation(such as, USB mass storage,
MMC card, ...), and Felipe Balbi has observed the failure.

This patch does below optimizations on the allocation of struct
parsed_partitions to try to address the issue:

- make parsed_partitions.parts as pointer so that the pointed memory can
  fit in 32KB buffer, then approximate 32KB memory can be saved

- vmalloc the buffer pointed by parsed_partitions.parts because 32KB is
  still a bit big for kmalloc

- given that many devices have the partition count limit, so only
  allocate disk_max_parts() partitions instead of 256 partitions always

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Reported-by: Felipe Balbi <balbi@ti.com>
Cc: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
SCSI: sg: Fix user memory corruption when SG_IO is interrupted by a signal

commit 35dc248383bbab0a7203fca4d722875bc81ef091 upstream.

There is a nasty bug in the SCSI SG_IO ioctl that in some circumstances
leads to one process writing data into the address space of some other
random unrelated process if the ioctl is interrupted by a signal.
What happens is the following:

 - A process issues an SG_IO ioctl with direction DXFER_FROM_DEV (ie the
   underlying SCSI command will transfer data from the SCSI device to
   the buffer provided in the ioctl)

 - Before the command finishes, a signal is sent to the process waiting
   in the ioctl.  This will end up waking up the sg_ioctl() code:

		result = wait_event_interruptible(sfp->read_wait,
			(srp_done(sfp, srp) || sdp->detached));

   but neither srp_done() nor sdp->detached is true, so we end up just
   setting srp->orphan and returning to userspace:

		srp->orphan = 1;
		write_unlock_irq(&sfp->rq_list_lock);
		return result;	/* -ERESTARTSYS because signal hit process */

   At this point the original process is done with the ioctl and
   blithely goes ahead handling the signal, reissuing the ioctl, etc.

 - Eventually, the SCSI command issued by the first ioctl finishes and
   ends up in sg_rq_end_io().  At the end of that function, we run through:

	write_lock_irqsave(&sfp->rq_list_lock, iflags);
	if (unlikely(srp->orphan)) {
		if (sfp->keep_orphan)
			srp->sg_io_owned = 0;
		else
			done = 0;
	}
	srp->done = done;
	write_unlock_irqrestore(&sfp->rq_list_lock, iflags);

	if (likely(done)) {
		/* Now wake up any sg_read() that is waiting for this
		 * packet.
		 */
		wake_up_interruptible(&sfp->read_wait);
		kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN);
		kref_put(&sfp->f_ref, sg_remove_sfp);
	} else {
		INIT_WORK(&srp->ew.work, sg_rq_end_io_usercontext);
		schedule_work(&srp->ew.work);
	}

   Since srp->orphan *is* set, we set done to 0 (assuming the
   userspace app has not set keep_orphan via an SG_SET_KEEP_ORPHAN
   ioctl), and therefore we end up scheduling sg_rq_end_io_usercontext()
   to run in a workqueue.

 - In workqueue context we go through sg_rq_end_io_usercontext() ->
   sg_finish_rem_req() -> blk_rq_unmap_user() -> ... ->
   bio_uncopy_user() -> __bio_copy_iov() -> copy_to_user().

   The key point here is that we are doing copy_to_user() on a
   workqueue -- that is, we're on a kernel thread with current->mm
   equal to whatever random previous user process was scheduled before
   this kernel thread.  So we end up copying whatever data the SCSI
   command returned to the virtual address of the buffer passed into
   the original ioctl, but it's quite likely we do this copying into a
   different address space!

As suggested by James Bottomley <James.Bottomley@hansenpartnership.com>,
add a check for current->mm (which is NULL if we're on a kernel thread
without a real userspace address space) in bio_uncopy_user(), and skip
the copy if we're on a kernel thread.

There's no reason that I can think of for any caller of bio_uncopy_user()
to want to do copying on a kernel thread with a random active userspace
address space.

Huge thanks to Costa Sapuntzakis <costa@purestorage.com> for the
original pointer to this bug in the sg code.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Tested-by: David Milburn <dmilburn@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
[lizf: backported to 3.4:
 - Use __bio_for_each_segment() instead of bio_for_each_segment_all()]
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SUNRPC: Fix memory corruption issue on 32-bit highmem systems

commit 347e2233b7667e336d9f671f1a52dfa3f0416e2c upstream.

Some architectures, such as ARM-32 do not return the same base address
when you call kmap_atomic() twice on the same page.
This causes problems for the memmove() call in the XDR helper routine
"_shift_data_right_pages()", since it defeats the detection of
overlapping memory ranges, and has been seen to corrupt memory.

The fix is to distinguish between the case where we're doing an
inter-page copy or not. In the former case of we know that the memory
ranges cannot possibly overlap, so we can additionally micro-optimise
by replacing memmove() with memcpy().

Reported-by: Mark Young <MYoung@nvidia.com>
Reported-by: Matt Craighead <mcraighead@nvidia.com>
Cc: Bruce Fields <bfields@fieldses.org>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Tested-by: Matt Craighead <mcraighead@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
target: Fix trailing ASCII space usage in INQUIRY vendor+model

commit ee60bddba5a5f23e39598195d944aa0eb2d455e5 upstream.

This patch fixes spc_emulate_inquiry_std() to add trailing ASCII
spaces for INQUIRY vendor + model fields following SPC-4 text:

  "ASCII data fields described as being left-aligned shall have any
   unused bytes at the end of the field (i.e., highest offset) and
   the unused bytes shall be filled with ASCII space characters (20h)."

This addresses a problem with Falconstor NSS multipathing.

Reported-by: Tomas Molota <tomas.molota@lightstorm.sk>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
LMK: Optimize lowmem_shrink.

By comparing with selected_oom_score_adj instead of min_score_adj,
we may do less calculation.

Signed-off-by: Leon Ma <xindong.ma@intel.com>

Signed-off-by: Paul Reioux <reioux@gmail.com>
Add VR Scheduler

Conflicts:
	block/Kconfig.iosched

Conflicts:
	block/Kconfig.iosched
	block/Makefile