The Linux kernel coding style guidelines suggest not using typedefs
for structure types. This patch gets rid of the typedef for
atiixp_ide_timing.

The following Coccinelle semantic patch detects the case:

@tn1@
type td;
@@

typedef struct { ... } td;

@script:python tf@
td << tn1.td;
tdres;
@@

coccinelle.tdres = td;

@@
type tn1.td;
identifier tf.tdres;
@@

-typedef
 struct
+  tdres
   { ... }
-td
 ;

@@
type tn1.td;
identifier tf.tdres;
@@

-td
+ struct tdres
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull percpu consistent-ops changes from Tejun Heo:
 "Way back, before the current percpu allocator was implemented, static
  and dynamic percpu memory areas were allocated and handled separately
  and had their own accessors.  The distinction has been gone for many
  years now; however, the now duplicate two sets of accessors remained
  with the pointer based ones - this_cpu_*() - evolving various other
  operations over time.  During the process, we also accumulated other
  inconsistent operations.

  This pull request contains Christoph's patches to clean up the
  duplicate accessor situation.  __get_cpu_var() uses are replaced with
  with this_cpu_ptr() and __this_cpu_ptr() with raw_cpu_ptr().

  Unfortunately, the former sometimes is tricky thanks to C being a bit
  messy with the distinction between lvalues and pointers, which led to
  a rather ugly solution for cpumask_var_t involving the introduction of
  this_cpu_cpumask_var_ptr().

  This converts most of the uses but not all.  Christoph will follow up
  with the remaining conversions in this merge window and hopefully
  remove the obsolete accessors"

* 'for-3.18-consistent-ops' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (38 commits)
  irqchip: Properly fetch the per cpu offset
  percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t -fix
  ia64: sn_nodepda cannot be assigned to after this_cpu conversion. Use __this_cpu_write.
  percpu: Resolve ambiguities in __get_cpu_var/cpumask_var_t
  Revert "powerpc: Replace __get_cpu_var uses"
  percpu: Remove __this_cpu_ptr
  clocksource: Replace __this_cpu_ptr with raw_cpu_ptr
  sparc: Replace __get_cpu_var uses
  avr32: Replace __get_cpu_var with __this_cpu_write
  blackfin: Replace __get_cpu_var uses
  tile: Use this_cpu_ptr() for hardware counters
  tile: Replace __get_cpu_var uses
  powerpc: Replace __get_cpu_var uses
  alpha: Replace __get_cpu_var
  ia64: Replace __get_cpu_var uses
  s390: cio driver &__get_cpu_var replacements
  s390: Replace __get_cpu_var uses
  mips: Replace __get_cpu_var uses
  MIPS: Replace __get_cpu_var uses in FPU emulator.
  arm: Replace __this_cpu_ptr with raw_cpu_ptr
  ...

Pull LLVM updates from Behan Webster:
 "These patches remove the use of VLAIS using a new SHASH_DESC_ON_STACK
  macro.

  Some of the previously accepted VLAIS removal patches haven't used
  this macro.  I will push new patches to consistently use this macro in
  all those older cases for 3.19"

[ More LLVM patches coming in through subsystem trees, and LLVM itself
  needs some fixes that are already in many distributions but not in
  released versions of LLVM.  Some day this will all "just work"  - Linus ]

* tag 'llvmlinux-for-v3.18' of git://git.linuxfoundation.org/llvmlinux/kernel:
  crypto: LLVMLinux: Remove VLAIS usage from crypto/testmgr.c
  security, crypto: LLVMLinux: Remove VLAIS from ima_crypto.c
  crypto: LLVMLinux: Remove VLAIS usage from libcrc32c.c
  crypto: LLVMLinux: Remove VLAIS usage from crypto/hmac.c
  crypto, dm: LLVMLinux: Remove VLAIS usage from dm-crypt
  crypto: LLVMLinux: Remove VLAIS from crypto/.../qat_algs.c
  crypto: LLVMLinux: Remove VLAIS from crypto/omap_sham.c
  crypto: LLVMLinux: Remove VLAIS from crypto/n2_core.c
  crypto: LLVMLinux: Remove VLAIS from crypto/mv_cesa.c
  crypto: LLVMLinux: Remove VLAIS from crypto/ccp/ccp-crypto-sha.c
  btrfs: LLVMLinux: Remove VLAIS
  crypto: LLVMLinux: Add macro to remove use of VLAIS in crypto code

Pull IOMMU updates from Joerg Roedel:
 "This pull-request includes:

   - change in the IOMMU-API to convert the former iommu_domain_capable
     function to just iommu_capable

   - various fixes in handling RMRR ranges for the VT-d driver (one fix
     requires a device driver core change which was acked by Greg KH)

   - the AMD IOMMU driver now assigns and deassigns complete alias
     groups to fix issues with devices using the wrong PCI request-id

   - MMU-401 support for the ARM SMMU driver

   - multi-master IOMMU group support for the ARM SMMU driver

   - various other small fixes all over the place"

* tag 'iommu-updates-v3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (41 commits)
  iommu/vt-d: Work around broken RMRR firmware entries
  iommu/vt-d: Store bus information in RMRR PCI device path
  iommu/vt-d: Only remove domain when device is removed
  driver core: Add BUS_NOTIFY_REMOVED_DEVICE event
  iommu/amd: Fix devid mapping for ivrs_ioapic override
  iommu/irq_remapping: Fix the regression of hpet irq remapping
  iommu: Fix bus notifier breakage
  iommu/amd: Split init_iommu_group() from iommu_init_device()
  iommu: Rework iommu_group_get_for_pci_dev()
  iommu: Make of_device_id array const
  amd_iommu: do not dereference a NULL pointer address.
  iommu/omap: Remove omap_iommu unused owner field
  iommu: Remove iommu_domain_has_cap() API function
  IB/usnic: Convert to use new iommu_capable() API function
  vfio: Convert to use new iommu_capable() API function
  kvm: iommu: Convert to use new iommu_capable() API function
  iommu/tegra: Convert to iommu_capable() API function
  iommu/msm: Convert to iommu_capable() API function
  iommu/vt-d: Convert to iommu_capable() API function
  iommu/fsl: Convert to iommu_capable() API function
  ...

Pull clock tree updates from Mike Turquette:
 "The clk tree changes for 3.18 are dominated by clock drivers.  Mostly
  fixes and enhancements to existing drivers as well as new drivers.
  This tag contains a bit more arch code than I usually take due to some
  OMAP2+ changes.  Additionally it contains the restart notifier
  handlers which are merged as a dependency into several trees.

  The PXA changes are the only messy part.  Due to having a stable tree
  I had to revert one patch and follow up with one more fix near the tip
  of this tag.  Some dead code is introduced but it will soon become
  live code after 3.18-rc1 is released as the rest of the PXA family is
  converted over to the common clock framework.

  Another trend in this tag is that multiple vendors have started to
  push the complexity of changing their CPU frequency into the clock
  driver, whereas this used to be done in CPUfreq drivers.

  Changes to the clk core include a generic gpio-clock type and a
  clk_set_phase() function added to the top-level clk.h api.  Due to
  some confusion on the fbdev mailing list the kernel boot parameters
  documentation was updated to further explain the clk_ignore_unused
  parameter, which is often required by users of the simplefb driver.

  Finally some fixes to the locking around the clock debugfs stuff was
  done to prevent deadlocks when interacting with other subsystems."

* tag 'clk-for-linus-3.18' of git://git.linaro.org/people/mike.turquette/linux: (99 commits)
  clk: pxa clocks build system fix
  Revert "arm: pxa: Transition pxa27x to clk framework"
  clk: samsung: register restart handlers for s3c2412 and s3c2443
  clk: rockchip: add restart handler
  clk: rockchip: rk3288: i2s_frac adds flag to set parent's rate
  doc/kernel-parameters.txt: clarify clk_ignore_unused
  arm: pxa: Transition pxa27x to clk framework
  dts: add devicetree bindings for pxa27x clocks
  clk: add pxa27x clock drivers
  arm: pxa: add clock pll selection bits
  clk: dts: document pxa clock binding
  clk: add pxa clocks infrastructure
  clk: gpio-gate: Ensure gpiod_ APIs are prototyped
  clk: ti: dra7-atl-clock: Mark the device as pm_runtime_irq_safe
  clk: ti: LLVMLinux: Move __init outside of type definition
  clk: ti: consider the fact that of_clk_get() might return an error
  clk: ti: dra7-atl-clock: fix a memory leak
  clk: ti: change clock init to use generic of_clk_init
  clk: hix5hd2: add I2C clocks
  clk: hix5hd2: add watchdog0 clocks
  ...

Pull MFD updates from Lee Jones:
 "Changes to existing drivers:
  - DT clean-ups in da9055-core, max14577, rn5t618, arizona, hi6421, stmpe, twl4030
  - Export symbols for use in modules in max14577
  - Plenty of static code analysis/Coccinelle fixes throughout the SS
  - Regmap clean-ups in arizona, wm5102, wm5110, da9052, tps65217, rk808
  - Remove unused/duplicate code in da9052, 88pm860x, ti_ssp, lpc_sch, arizona
  - Bug fixes in ti_am335x_tscadc, da9052, ti_am335x_tscadc, rtsx_pcr
  - IRQ fixups in arizona, stmpe, max14577
  - Regulator related changes in axp20x
  - Pass DMA coherency information from parent => child in MFD core
  - Rename DT document files for consistency
  - Add ACPI support to the MFD core
  - Add Andreas Werner to MAINTAINERS for MEN F21BMC

 New drivers/supported devices:
  - New driver for MEN 14F021P00 Board Management Controller
  - New driver for Ricoh RN5T618 PMIC
  - New driver for Rockchip RK808
  - New driver for HiSilicon Hi6421 PMIC
  - New driver for Qualcomm SPMI PMICs
  - Add support for Intel Braswell in lpc_ich
  - Add support for Intel 9 Series PCH in lpc_ich
  - Add support for Intel Quark ILB in lpc_sch"

[ Delayed to after the poweer/reset pull due to Kconfig problems with
  recursive Kconfig select/depends-on chains.   - Linus ]

* tag 'mfd-for-linus-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd: (79 commits)
  mfd: cros_ec: wait for completion of commands that return IN_PROGRESS
  i2c: i2c-cros-ec-tunnel: Set retries to 3
  mfd: cros_ec: move locking into cros_ec_cmd_xfer
  mfd: cros_ec: stop calling ->cmd_xfer() directly
  mfd: cros_ec: Delay for 50ms when we see EC_CMD_REBOOT_EC
  MAINTAINERS: Adds Andreas Werner to maintainers list for MEN F21BMC
  mfd: arizona: Correct mask to allow setting micbias external cap
  mfd: Add ACPI support
  Revert "mfd: wm5102: Manually apply register patch"
  mfd: ti_am335x_tscadc: Update logic in CTRL register for 5-wire TS
  mfd: dt-bindings: atmel-gpbr: Rename doc file to conform to naming convention
  mfd: dt-bindings: qcom-pm8xxx: Rename doc file to conform to naming convention
  mfd: Inherit coherent_dma_mask from parent device
  mfd: Document DT bindings for Qualcomm SPMI PMICs
  mfd: Add support for Qualcomm SPMI PMICs
  mfd: dt-bindings: pm8xxx: Add new compatible string
  mfd: axp209x: Drop the parent supplies field
  mfd: twl4030-power: Use 'ti,system-power-controller' as alternative way to support system power off
  mfd: dt-bindings: twl4030-power: Use the standard property to mark power control
  mfd: syscon: Add Atmel GPBR DT bindings documention
  ...

Pull power supply and reset updates from Sebastian Reichel:
 - Initial support for the following chips
   * max77836 (charger)
   * max14577 (charger)
   * bq27742 (battery gauge)
   * ltc2952 (poweroff)
   * stih416 (restart)
   * syscon-reboot (restart)
   * gpio-restart (restart)
 - cleanup of power supply core
 - misc fixes in power supply and reset drivers

* tag 'for-v3.18' of git://git.infradead.org/battery-2.6: (48 commits)
  power: ab8500_fg: Fix build warning
  Documentation: charger: max14577: Update the date of introducing ABI
  power: reset: corrections for simple syscon reboot driver
  Documentation: power: reset: Add documentation for generic SYSCON reboot driver
  power: reset: Add generic SYSCON register mapped reset
  bq27x00_battery: Fix flag reading for bq27742
  power: reset: use restart_notifier mechanism for msm-poweroff
  power: Add simple gpio-restart driver
  power: reset: st: Provide DT bindings for ST's Power Reset driver
  power: reset: Add restart functionality for STiH41x platforms
  power: charger-manager: Fix NULL pointer exception with missing cm-fuel-gauge
  power: max14577: Fix circular config SYSFS dependency
  power: gpio-charger: do not use gpio value directly
  power: max8925: Use of_get_child_by_name
  power: max8925: Fix NULL ptr dereference on memory allocation failure
  bq27x00_battery: Add support to bq27742
  Documentation: charger: max14577: Document exported sysfs entry
  devicetree: mfd: max14577: Add device tree bindings document
  power: max17040: Add ID for MAX77836 Fuel Gauge block
  charger: max14577: Configure battery-dependent settings from DTS and sysfs
  ...

Conflicts:
	drivers/power/reset/Kconfig
	drivers/power/reset/Makefile

Pull Ceph updates from Sage Weil:
 "There is the long-awaited discard support for RBD (Guangliang Zhao,
  Josh Durgin), a pile of RBD bug fixes that didn't belong in late -rc's
  (Ilya Dryomov, Li RongQing), a pile of fs/ceph bug fixes and
  performance and debugging improvements (Yan, Zheng, John Spray), and a
  smattering of cleanups (Chao Yu, Fabian Frederick, Joe Perches)"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client: (40 commits)
  ceph: fix divide-by-zero in __validate_layout()
  rbd: rbd workqueues need a resque worker
  libceph: ceph-msgr workqueue needs a resque worker
  ceph: fix bool assignments
  libceph: separate multiple ops with commas in debugfs output
  libceph: sync osd op definitions in rados.h
  libceph: remove redundant declaration
  ceph: additional debugfs output
  ceph: export ceph_session_state_name function
  ceph: include the initial ACL in create/mkdir/mknod MDS requests
  ceph: use pagelist to present MDS request data
  libceph: reference counting pagelist
  ceph: fix llistxattr on symlink
  ceph: send client metadata to MDS
  ceph: remove redundant code for max file size verification
  ceph: remove redundant io_iter_advance()
  ceph: move ceph_find_inode() outside the s_mutex
  ceph: request xattrs if xattr_version is zero
  rbd: set the remaining discard properties to enable support
  rbd: use helpers to handle discard for layered images correctly
  ...

Pull pivot_root() fix from Andy Lutomirski.

Prevent a leak of unreachable mounts.

* 'CVE-2014-7970' of git://git.kernel.org/pub/scm/linux/kernel/git/luto/linux:
  mnt: Prevent pivot_root from creating a loop in the mount tree

Andy Lutomirski recently demonstrated that when chroot is used to set
the root path below the path for the new ``root'' passed to pivot_root
the pivot_root system call succeeds and leaks mounts.

In examining the code I see that starting with a new root that is
below the current root in the mount tree will result in a loop in the
mount tree after the mounts are detached and then reattached to one
another.  Resulting in all kinds of ugliness including a leak of that
mounts involved in the leak of the mount loop.

Prevent this problem by ensuring that the new mount is reachable from
the current root of the mount tree.

[Added stable cc.  Fixes CVE-2014-7970.  --Andy]

Cc: stable@vger.kernel.org
Reported-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/87bnpmihks.fsf@x220.int.ebiederm.orgSigned-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>

The 'stripe_unit' field is 64 bits, casting it to 32 bits can result zero.
Signed-off-by: Yan, Zheng <zyan@redhat.com>

Need to use WQ_MEM_RECLAIM for our workqueues to prevent I/O lockups
under memory pressure - we sit on the memory reclaim path.

Cc: stable@vger.kernel.org # 3.17, needs backporting for 3.16
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>
Tested-by: Micha Krause <micha@krausam.de>
Reviewed-by: Sage Weil <sage@redhat.com>

Commit f363e45f ("net/ceph: make ceph_msgr_wq non-reentrant")
effectively removed WQ_MEM_RECLAIM flag from ceph_msgr_wq.  This is
wrong - libceph is very much a memory reclaim path, so restore it.

Cc: stable@vger.kernel.org # needs backporting for < 3.12
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>
Tested-by: Micha Krause <micha@krausam.de>
Reviewed-by: Sage Weil <sage@redhat.com>

Fix some coccinelle warnings:
fs/ceph/caps.c:2400:6-10: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2401:6-15: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2402:6-17: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2403:6-22: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2404:6-22: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2405:6-19: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2440:4-20: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2469:3-16: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2490:2-18: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2519:3-7: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2549:3-12: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2575:2-6: WARNING: Assignment of bool to 0/1
fs/ceph/caps.c:2589:3-7: WARNING: Assignment of bool to 0/1
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>

For requests with multiple ops, separate ops with commas instead of \t,
which is a field separator here.
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>

Bring in missing osd ops and strings, use macros to eliminate multiple
points of maintenance.
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>

ceph_release_page_vector was defined twice in libceph.h
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Ilya Dryomov <idryomov@redhat.com>

MDS session state and client global ID is
useful instrumentation when testing.
Signed-off-by: John Spray <john.spray@redhat.com>

...so that it can be used from the ceph debugfs
code when dumping session info.
Signed-off-by: John Spray <john.spray@redhat.com>

Current code set new file/directory's initial ACL in a non-atomic
manner.
Client first sends request to MDS to create new file/directory, then set
the initial ACL after the new file/directory is successfully created.

The fix is include the initial ACL in create/mkdir/mknod MDS requests.
So MDS can handle creating file/directory and setting the initial ACL in
one request.
Signed-off-by: Yan, Zheng <zyan@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>

Current code uses page array to present MDS request data. Pages in the
array are allocated/freed by caller of ceph_mdsc_do_request(). If request
is interrupted, the pages can be freed while they are still being used by
the request message.

The fix is use pagelist to present MDS request data. Pagelist is
reference counted.
Signed-off-by: Yan, Zheng <zyan@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>

this allow pagelist to present data that may be sent multiple times.
Signed-off-by: Yan, Zheng <zyan@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>

only regular file and directory have vxattrs.
Signed-off-by: Yan, Zheng <zyan@redhat.com>

Implement version 2 of CEPH_MSG_CLIENT_SESSION syntax,
which includes additional client metadata to allow
the MDS to report on clients by user-sensible names
like hostname.
Signed-off-by: John Spray <john.spray@redhat.com>
Reviewed-by: Yan, Zheng <zyan@redhat.com>

Both ceph_update_writeable_page and ceph_setattr will verify file size
with max size ceph supported.
There are two caller for ceph_update_writeable_page, ceph_write_begin and
ceph_page_mkwrite. For ceph_write_begin, we have already verified the size in
generic_write_checks of ceph_write_iter; for ceph_page_mkwrite, we have no
chance to change file size when mmap. Likewise we have already verified the size
in inode_change_ok when we call ceph_setattr.
So let's remove the redundant code for max file size verification.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Reviewed-by: Yan, Zheng <zyan@redhat.com>

ceph_sync_read and generic_file_read_iter() have already advanced the
IO iterator.
Signed-off-by: Yan, Zheng <zyan@redhat.com>

ceph_find_inode() may wait on freeing inode, using it inside the s_mutex
may cause deadlock. (the freeing inode is waiting for OSD read reply, but
dispatch thread is blocked by the s_mutex)
Signed-off-by: Yan, Zheng <zyan@redhat.com>
Reviewed-by: Sage Weil <sage@redhat.com>

Following sequence of events can happen.
  - Client releases an inode, queues cap release message.
  - A 'lookup' reply brings the same inode back, but the reply
    doesn't contain xattrs because MDS didn't receive the cap release
    message and thought client already has up-to-data xattrs.

The fix is force sending a getattr request to MDS if xattrs_version
is 0. The getattr mask is set to CEPH_STAT_CAP_XATTR, so MDS knows client
does not have xattr.
Signed-off-by: Yan, Zheng <zyan@redhat.com>

max_discard_sectors must be set for the queue to support discard.
Operations implementing discard for rbd zero data, so report that.
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>

Only allocate two osd ops for discard requests, since the
preallocation hint is only added for regular writes.  Use
rbd_img_obj_request_fill() to recreate the original write or discard
osd operations, isolating that logic to one place, and change the
assert in rbd_osd_req_create_copyup() to accept discard requests as
well.
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>

rbd_img_request_fill() creates a ceph_osd_request and has logic for
adding the appropriate osd ops to it based on the request type and
image properties.

For layered images, the original rbd_obj_request is resent with a
copyup operation in front, using a new ceph_osd_request. The logic for
adding the original operations should be the same as when first
sending them, so move it to a helper function.

op_type only needs to be checked once, so create a helper for that as
well and call it outside the loop in rbd_img_request_fill().
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>

Discard requests are a form of write, so they should go through the
same process as plain write requests and trigger copy-on-write for
layered images.
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>

Discard may try to delete an object from a non-layered image that does not exist.
If this occurs, the image already has no data in that range, so change the
result to success.
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>

Discards take a reference to the snapshot context of an image when
they are created.  This reference needs to be cleaned up when the
request is done just as it is for regular writes.
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>

In rbd_img_request_fill() the image size is only checked to determine
whether we can truncate an object instead of zeroing it for discard
requests. Take rbd_dev->header_rwsem while reading the image size, and
move this read into the discard check, so that non-discard ops don't
need to take the semaphore in this function.
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>

This patch add the discard support for rbd driver.

There are three types operation in the driver:
1. The objects would be removed if they completely contained
   within the discard range.
2. The objects would be truncated if they partly contained within
   the discard range, and align with their boundary.
3. Others would be zeroed.

A discard request from blkdev_issue_discard() is defined which
REQ_WRITE and REQ_DISCARD both marked and no data, so we must
check the REQ_DISCARD first when getting the request type.

This resolve:
	http://tracker.ceph.com/issues/190

[ Ilya Dryomov: This is incomplete and somewhat buggy, see follow up
  commits by Josh Durgin for refinements and fixes which weren't
  folded in to preserve authorship. ]
Signed-off-by: Guangliang Zhao <lucienchao@gmail.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>

It could only handle the read and write operations now,
extend it for the coming discard support.
Signed-off-by: Guangliang Zhao <lucienchao@gmail.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>

It need to copyup the parent's content when layered writing,
but an entire object write would overwrite it, so skip it.
Signed-off-by: Guangliang Zhao <lucienchao@gmail.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>

To clarify the conditions and make it easier to add new ones.
Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>

These fields may both change while the image is mapped if a snapshot
is created or deleted or the image is resized.  They are guarded by
rbd_dev->header_rwsem, so hold that while reading them, and store a
local copy to refer to outside of the critical section. The local copy
will stay consistent since the snapshot context is reference counted,
and the mapping size is just a u64. This prevents torn loads from
giving us inconsistent values.

Move reading header.snapc into the caller of rbd_img_request_create()
so that we only need to take the semaphore once. The read-only caller,
rbd_parent_request_create() can just pass NULL for snapc, since the
snapshot context is only relevant for writes.
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>