The following commit:

commit aa4d86163e4e ("block: loop: switch to VFS ITER_BVEC")

replaced __do_lo_send_write(), which used ITER_KVEC iterators, with
lo_write_bvec() which uses ITER_BVEC iterators.  In this change, though,
the WRITE flag was lost:

-       iov_iter_kvec(&from, ITER_KVEC | WRITE, &kvec, 1, len);
+       iov_iter_bvec(&i, ITER_BVEC, bvec, 1, bvec->bv_len);

This flag is necessary for the DAX case because we make decisions based on
whether or not the iterator is a READ or a WRITE in dax_iomap_actor() and
in dax_iomap_rw().

We end up going through this path in configurations where we combine a PMEM
device with 4k sectors, a loopback device and DAX.  The consequence of this
missed flag is that what we intend as a write actually turns into a read in
the DAX code, so no data is ever written.

The very simplest test case is to create a loopback device and try and
write a small string to it, then hexdump a few bytes of the device to see
if the write took.  Without this patch you read back all zeros, with this
you read back the string you wrote.

For XFS this causes us to fail or panic during the following xfstests:

	xfs/074 xfs/078 xfs/216 xfs/217 xfs/250

For ext4 we have a similar issue where writes never happen, but we don't
currently have any xfstests that use loopback and show this issue.

Fix this by restoring the WRITE flag argument to iov_iter_bvec().  This
causes the xfstests to all pass.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Fixes: commit aa4d86163e4e ("block: loop: switch to VFS ITER_BVEC")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull a xen_blkfront fix from Konrad:

"It has one simple fix for the multi-queue support not showing up after
a block device was detached/re-attached."

* 'stable/for-jens-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
  xen-blkfront: move negotiate_mq to cover all cases of new VBDs

negotiate_mq should happen in all cases of a new VBD being discovered by
xen-blkfront, whether called through _probe() or a hot-attached new VBD
from dom-0 via xenstore. Otherwise, hot-attached new VBDs are left
configured without multi-queue.

Signed-off-by: Bhavesh Davda <bhavesh.davda@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Fix a typo in pkt_start_recovery.

Fixes: 74d46992e0d9 ("block: replace bi_bdev with a gendisk pointer and partitions index")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

It seems that the proper value to return in this particular case is the
one contained into variable new_index instead of ret.

Addresses-Coverity-ID: 1465148 ("Copy-paste error")
Fixes: e46c7287b1c2 ("nbd: add a basic netlink interface")
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Rename get_disk() to get_disk_and_module() to make sure what the
function does. It's not a great name but at least it is now clear that
put_disk() is not it's counterpart.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull ceph updates from Ilya Dryomov:
 "Things have been very quiet on the rbd side, as work continues on the
  big ticket items slated for the next merge window.

  On the CephFS side we have a large number of cap handling
  improvements, a fix for our long-standing abuse of ->journal_info in
  ceph_readpages() and yet another dentry pointer management patch"

* tag 'ceph-for-4.16-rc1' of git://github.com/ceph/ceph-client:
  ceph: improving efficiency of syncfs
  libceph: check kstrndup() return value
  ceph: try to allocate enough memory for reserved caps
  ceph: fix race of queuing delayed caps
  ceph: delete unreachable code in ceph_check_caps()
  ceph: limit rate of cap import/export error messages
  ceph: fix incorrect snaprealm when adding caps
  ceph: fix un-balanced fsc->writeback_count update
  ceph: track read contexts in ceph_file_info
  ceph: avoid dereferencing invalid pointer during cached readdir
  ceph: use atomic_t for ceph_inode_info::i_shared_gen
  ceph: cleanup traceless reply handling for rename
  ceph: voluntarily drop Fx cap for readdir request
  ceph: properly drop caps for setattr request
  ceph: voluntarily drop Lx cap for link/rename requests
  ceph: voluntarily drop Ax cap for requests that create new inode
  rbd: whitelist RBD_FEATURE_OPERATIONS feature bit
  rbd: don't NULL out ->obj_request in rbd_img_obj_parent_read_full()
  rbd: use kmem_cache_zalloc() in rbd_img_request_create()
  rbd: obj_request->completion is unused

Pull virtio/vhost updates from Michael Tsirkin:
 "virtio, vhost: fixes, cleanups, features

  This includes the disk/cache memory stats for for the virtio balloon,
  as well as multiple fixes and cleanups"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  vhost: don't hold onto file pointer for VHOST_SET_LOG_FD
  vhost: don't hold onto file pointer for VHOST_SET_VRING_ERR
  vhost: don't hold onto file pointer for VHOST_SET_VRING_CALL
  ringtest: ring.c malloc & memset to calloc
  virtio_vop: don't kfree device on register failure
  virtio_pci: don't kfree device on register failure
  virtio: split device_register into device_initialize and device_add
  vhost: remove unused lock check flag in vhost_dev_cleanup()
  vhost: Remove the unused variable.
  virtio_blk: print capacity at probe time
  virtio: make VIRTIO a menuconfig to ease disabling it all
  virtio/ringtest: virtio_ring: fix up need_event math
  virtio/ringtest: fix up need_event math
  virtio: virtio_mmio: make of_device_ids const.
  firmware: Use PTR_ERR_OR_ZERO()
  virtio-mmio: Use PTR_ERR_OR_ZERO()
  vhost/scsi: Improve a size determination in four functions
  virtio_balloon: include disk/file caches memory statistics

Pull PCI updates from Bjorn Helgaas:

 - skip AER driver error recovery callbacks for correctable errors
   reported via ACPI APEI, as we already do for errors reported via the
   native path (Tyler Baicar)

 - fix DPC shared interrupt handling (Alex Williamson)

 - print full DPC interrupt number (Keith Busch)

 - enable DPC only if AER is available (Keith Busch)

 - simplify DPC code (Bjorn Helgaas)

 - calculate ASPM L1 substate parameter instead of hardcoding it (Bjorn
   Helgaas)

 - enable Latency Tolerance Reporting for ASPM L1 substates (Bjorn
   Helgaas)

 - move ASPM internal interfaces out of public header (Bjorn Helgaas)

 - allow hot-removal of VGA devices (Mika Westerberg)

 - speed up unplug and shutdown by assuming Thunderbolt controllers
   don't support Command Completed events (Lukas Wunner)

 - add AtomicOps support for GPU and Infiniband drivers (Felix Kuehling,
   Jay Cornwall)

 - expose "ari_enabled" in sysfs to help NIC naming (Stuart Hayes)

 - clean up PCI DMA interface usage (Christoph Hellwig)

 - remove PCI pool API (replaced with DMA pool) (Romain Perier)

 - deprecate pci_get_bus_and_slot(), which assumed PCI domain 0 (Sinan
   Kaya)

 - move DT PCI code from drivers/of/ to drivers/pci/ (Rob Herring)

 - add PCI-specific wrappers for dev_info(), etc (Frederick Lawler)

 - remove warnings on sysfs mmap failure (Bjorn Helgaas)

 - quiet ROM validation messages (Alex Deucher)

 - remove redundant memory alloc failure messages (Markus Elfring)

 - fill in types for compile-time VGA and other I/O port resources
   (Bjorn Helgaas)

 - make "pci=pcie_scan_all" work for Root Ports as well as Downstream
   Ports to help AmigaOne X1000 (Bjorn Helgaas)

 - add SPDX tags to all PCI files (Bjorn Helgaas)

 - quirk Marvell 9128 DMA aliases (Alex Williamson)

 - quirk broken INTx disable on Ceton InfiniTV4 (Bjorn Helgaas)

 - fix CONFIG_PCI=n build by adding dummy pci_irqd_intx_xlate() (Niklas
   Cassel)

 - use DMA API to get MSI address for DesignWare IP (Niklas Cassel)

 - fix endpoint-mode DMA mask configuration (Kishon Vijay Abraham I)

 - fix ARTPEC-6 incorrect IS_ERR() usage (Wei Yongjun)

 - add support for ARTPEC-7 SoC (Niklas Cassel)

 - add endpoint-mode support for ARTPEC (Niklas Cassel)

 - add Cadence PCIe host and endpoint controller driver (Cyrille
   Pitchen)

 - handle multiple INTx status bits being set in dra7xx (Vignesh R)

 - translate dra7xx hwirq range to fix INTD handling (Vignesh R)

 - remove deprecated Exynos PHY initialization code (Jaehoon Chung)

 - fix MSI erratum workaround for HiSilicon Hip06/Hip07 (Dongdong Liu)

 - fix NULL pointer dereference in iProc BCMA driver (Ray Jui)

 - fix Keystone interrupt-controller-node lookup (Johan Hovold)

 - constify qcom driver structures (Julia Lawall)

 - rework Tegra config space mapping to increase space available for
   endpoints (Vidya Sagar)

 - simplify Tegra driver by using bus->sysdata (Manikanta Maddireddy)

 - remove PCI_REASSIGN_ALL_BUS usage on Tegra (Manikanta Maddireddy)

 - add support for Global Fabric Manager Server (GFMS) event to
   Microsemi Switchtec switch driver (Logan Gunthorpe)

 - add IDs for Switchtec PSX 24xG3 and PSX 48xG3 (Kelvin Cao)

* tag 'pci-v4.16-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (140 commits)
  PCI: cadence: Add EndPoint Controller driver for Cadence PCIe controller
  dt-bindings: PCI: cadence: Add DT bindings for Cadence PCIe endpoint controller
  PCI: endpoint: Fix EPF device name to support multi-function devices
  PCI: endpoint: Add the function number as argument to EPC ops
  PCI: cadence: Add host driver for Cadence PCIe controller
  dt-bindings: PCI: cadence: Add DT bindings for Cadence PCIe host controller
  PCI: Add vendor ID for Cadence
  PCI: Add generic function to probe PCI host controllers
  PCI: generic: fix missing call of pci_free_resource_list()
  PCI: OF: Add generic function to parse and allocate PCI resources
  PCI: Regroup all PCI related entries into drivers/pci/Makefile
  PCI/DPC: Reformat DPC register definitions
  PCI/DPC: Add and use DPC Status register field definitions
  PCI/DPC: Squash dpc_rp_pio_get_info() into dpc_process_rp_pio_error()
  PCI/DPC: Remove unnecessary RP PIO register structs
  PCI/DPC: Push dpc->rp_pio_status assignment into dpc_rp_pio_get_info()
  PCI/DPC: Squash dpc_rp_pio_print_error() into dpc_rp_pio_get_info()
  PCI/DPC: Make RP PIO log size check more generic
  PCI/DPC: Rename local "status" to "dpc_status"
  PCI/DPC: Squash dpc_rp_pio_print_tlp_header() into dpc_rp_pio_print_error()
  ...

Pull more block updates from Jens Axboe:
 "Most of this is fixes and not new code/features:

   - skd fix from Arnd, fixing a build error dependent on sla allocator
     type.

   - blk-mq scheduler discard merging fixes, one from me and one from
     Keith. This fixes a segment miscalculation for blk-mq-sched, where
     we mistakenly think two segments are physically contigious even
     though the request isn't carrying real data. Also fixes a bio-to-rq
     merge case.

   - Don't re-set a bit on the buffer_head flags, if it's already set.
     This can cause scalability concerns on bigger machines and
     workloads. From Kemi Wang.

   - Add BLK_STS_DEV_RESOURCE return value to blk-mq, allowing us to
     distuingish between a local (device related) resource starvation
     and a global one. The latter might happen without IO being in
     flight, so it has to be handled a bit differently. From Ming"

* tag 'for-linus-20180204' of git://git.kernel.dk/linux-block:
  block: skd: fix incorrect linux/slab_def.h inclusion
  buffer: Avoid setting buffer bits that are already set
  blk-mq-sched: Enable merging discard bio into request
  blk-mq: fix discard merge with scheduler attached
  blk-mq: introduce BLK_STS_DEV_RESOURCE