ext4: speed up truncate/unlink by not using bforget() unless needed

Do not iterate over data blocks scanning for bh's to forget as they're
never exist. This improves time taken by unlink / truncate syscall.
Tested by continuously truncating file that is being written by dd.
Another test is rm -rf of linux tree while tar unpacks it. With
ordered data mode condition unlikely(!tbh) was always met in
ext4_free_blocks. With journal data mode tbh was found only few times,
so optimisation is also possible.

Unlinking fallocated 60G file after doing sync && echo 3 >
/proc/sys/vm/drop_caches && time rm --help

X86 before (linux 3.6-rc4):
# time rm -f test1
real    0m2.710s
user    0m0.000s
sys     0m1.530s

X86 after:
# time rm -f test1
real    0m0.644s
user    0m0.003s
sys     0m0.060s

MIPS before (linux 2.6.37):
# time rm -f test1
real    0m 4.93s
user    0m 0.00s
sys     0m 4.61s

MIPS after:
# time rm -f test1
real    0m 0.16s
user    0m 0.00s
sys     0m 0.06s

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrey Sidorov <qrxd43@motorola.com>
msm: iommu: re-use existing buffers for `extra' mappings
There is a bug on some hardware that requires us to overmap Iommu
mappings by 2x. Currently, we set aside a dummy buffer onto which we
map all of these dummy mappings. In general, for large mappings it's
nice to use the more efficient iommu_map_range instead of calling
iommu_map repeatedly. However, with our current approach in
msm_iommu_map_extra we can't use iommu_map_range for page_sizes larger
than the dummy buffer. To avoid wasting memory by increasing the size
of the dummy buffer, we can simply remap on top of the the buffer
being mapped in the first place. Since the second mapping should never
be used (besides by the buggy hardware) this should not be a problem.

Re-use existing buffers for all `extra' mappings. Essentially, map the
same physical address range twice. To be extra safe, make the second
mapping read-only.

Change-Id: I35462ad50de8da1f2befa3e3f0895925535cdc98
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
gpu: ion: remove stale variable

Tracking the number of user mappings should be done in the Ion
heaps. Remove the variable that was used to track this in core Ion.

Change-Id: I715280515e3010bd002314aefe0ec8cdb37c143d
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
gpu: ion: Remove get_flags ioctl

There are no callers of the get flags ioctl. Remove it
before anyone tries to use it again.

Change-Id: I857ef705fc864cce49f671124b96bd9f47b66ab2
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
gpu: ion: Minimize allocation fallback delay

When we allocate from iommu heap we first try to allocate 1M pages. If
that fails we try 64K pages, which falls back to 4K pages. However,
we don't want to incur too much overhead when allocating with fallbacks
so we don't want the higher order page allocation to retry, perform
reclaim, or run memory compaction.

Configure the GFP flags to ensure that when we allocate pages greater
than order 0 we don't try to do any retries, reclaim, access emergency
pools, or run memory compaction. This will ensure lower memory allocation
latency for applications.

CRs-Fixed: 470389
Change-Id: Ibb3483dddbedbc733a1f7968821e7bc47bedffcd
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
gpu: ion: Remove code for reusable heap

The reusable feature is no longer supported. Remove
the associated code.

Change-Id: I7cf6eb302969287d629603fa0ea05ad9714bfb70
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Revert "msm: iommu: re-use existing buffers for `extra' mappings"