Reorganize 18.07 Changelog entries.

## v18.07: (Upcoming Release)

### bdev

A new public header file bdev_module.h has been introduced to facilitate the

development of new bdev modules. This header includes an interface for the

spdk_bdev_part and spdk_bdev_part_base objects to enable the creation of

multiple virtual bdevs on top of a single base bdev and should act as the

primary API for module authors.

spdk_bdev_get_opts() and spdk_bdev_set_opts() were added to set bdev-wide

options.

A mechanism for handling out of memory condition errors (ENOMEM) returned from

I/O submission requests at the bdev layer has been added. See

spdk_bdev_queue_io_wait().

The spdk_bdev_get_io_stat() function now returns cumulative totals instead of

resetting on each call. This allows multiple callers to query I/O statistics

without conflicting with each other. Existing users will need to adjust their

code to record the previous I/O statistics to calculate the delta between calls.

I/O queue depth tracking and samples options have been added. See

spdk_bdev_get_qd(), spdk_bdev_get_qd_sampling_period(), and

spdk_bdev_set_qd_sampling_period().

### RAID module

A new bdev module called "raid" has been added as experimental module which

aggregates underlying nvme bdevs and expose a single raid bdev to upper bdev

layers. Over this LVS/LVOL can be created as per use-cases and they can be

exposed to NVMe-oF subsystems. Please note that vhost will not work with RAID

module as RAID module does not support multipe IOV Vectors yet.

aggregates underlying NVMe bdevs and exposes a single raid bdev. Please note

that vhost will not work with this module because it does not yet have support

for multi-element io vectors.

### Log

The debug log component flag has been renamed from `-t` to `-L` to prevent confusion

with tracepoints and to allow the option to be added to tools that already use `-t`

to mean something else.

The debug log component flag available on several SPDK applications has been

renamed from `-t` to `-L` to prevent confusion with tracepoints and to allow the

option to be added to tools that already use `-t` to mean something else.

### Blobstore

A new function, spdk_bs_dump(), has been added that dumps all of the contents of

a blobstore to a file pointer. This includes the metadata and is very useful for

debugging.

Two new operations have been added for thin-provisioned blobs.

spdk_bs_inflate_blob() will allocate clusters for all thinly provisioned regions

of the blob and populate them with the correct data by reading from the backing

blob(s). spdk_bs_blob_decouple_parent() works similarly, but will only allocate

clusters that correspond to data in the blob's immediate parent. Clusters

allocated to grandparents or that aren't allocated at all will remain

thin-provisioned.

### BlobFS

Changed the return type of spdk_file_truncate() from void to int to allow the

propagation of `ENOMEM` errors.

### NVMe Driver

New API function spdk_nvme_qpair_add_cmd_error_injection() and

spdk_nvme_qpair_remove_cmd_error_injection() have been added for NVMe error emulation,

users can set specified command with specified error status for error emulation.

The new API functions spdk_nvme_qpair_add_cmd_error_injection() and

spdk_nvme_qpair_remove_cmd_error_injection() have been added for NVMe error

emulation. Users can set a specified command to fail with a particular error

status.

Change the name `timeout_sec` parameter to `timeout_us` in API function

spdk_nvme_ctrlr_register_timeout_callback, and also change the type from uint32_t to

uint64_t. This will give users more fine-grained control over the timeout period for

calling callback functions.

Changed the name `timeout_sec` parameter to `timeout_us` in

spdk_nvme_ctrlr_register_timeout_callback(), and also changed the type from

uint32_t to uint64_t. This will give users more fine-grained control over the

timeout period.

Basic support for Open Channel SSDs was added. See nvme_ocssd.h

### NVMe Over Fabrics

The spdk_nvmf_tgt_destroy() function is now asynchronous and takes a callback

as a parameter.

spdk_nvmf_qpair_disconnect() was added to allow the user to disconnect qpairs.

spdk_nvmf_subsystem_get_max_namespaces() was added to query the maximum allowed

number of namespaces for a given subsystem.

### Build System

The build system now generates a combined shared library (libspdk.so) that may be used

in place of the individual static libraries (libspdk_*.a).

The combined library includes all components of SPDK and is intended to make linking

against SPDK easier.

The static libraries are also still provided for users that prefer to link only the

minimal set of components required.

The build system now generates a combined shared library (libspdk.so) that may

be used in place of the individual static libraries (libspdk_*.a). The combined

library includes all components of SPDK and is intended to make linking against

SPDK easier. The static libraries are also still provided for users that prefer

to link only the minimal set of components required.

### git pre-commit and pre-push hooks

The pre-commit hook will run `scripts/check_format.sh` and verify there are no

formating errors before allowing `git commit` to run. The pre-push hook runs

`make CONFIG_WERROR=y` with and without `CONFIG_DEBUG=y` using both the gcc and

clang compiler before allowing `git push` to run. Following each DEBUG build

`test/unit/unittest.sh` is run and verified. Results are recorded in the

`make.log` file.

A new configure option was added `--with-crypto` that, when set, will build the crypto

vbdev as well as its dependencies.

To enable type: 'git config core.hooksPath .githooks'. To override after

configuration use the `git --no-verify` flag.

### RPC

The `start_nbd_disk` RPC method now returns the path to the kernel NBD device node

rather than always returning `true`.

### Bdev

The spdk_bdev_get_io_stat() function now returns cumulative totals instead of resetting

on each call. This allows multiple callers to query I/O statistics without conflicting

with each other. Existing users will need to adjust their code to record the previous

I/O statistics to calculate the delta between calls.

### DPDK 18.05

A new public header file bdev_module.h has been introduced to facilitate the development

of new bdev modules. This header includes an interface for the spdk_bdev_part and

spdk_bdev_part_base objects to enable the creation of multiple virtual bdevs on top of a

single base bdev.

The DPDK submodule has been rebased on the DPDK 18.05 release.  DPDK 18.05 supports

dynamic memory allocation, but due to some issues found after the DPDK 18.05 release,

that support is not enabled for SPDK 18.07.  Therefore, SPDK 18.07 will continue to use

the legacy memory allocation model.  The plan is to enable dynamic memory allocation

after the DPDK 18.08 release which should fix these issues.

### Env

### Environment Abstraction Layer and Event Framework

The spdk_mem_map_translate() function now takes a size parameter to indicate the size of

the memory region.  This can be used by environment implementations to validate the

public API that was previously in spdk/io_channel.h is now in spdk/thread.h The

file spdk/io_channel.h remains and includes spdk/thread.h.

### NVMe Over Fabrics

The spdk_nvmf_tgt_destroy() function is now asynchronous and takes a callback

as a parameter.

### git pre-commit and pre-push hooks

The pre-commit hook will run `scripts/check_format.sh` and verify there are no formating

errors before allowing `git commit` to run. The pre-push hook runs `make CONFIG_WERROR=y`

with and without `CONFIG_DEBUG=y` using both the gcc and clang compiler before allowing

`git push` to run.  Following each DEBUG build `test/unit/unittest.sh` is run and verified.

Results are recorded in the `make.log` file.

To enable type: 'git config core.hooksPath .githooks'. To override after configuration use

the `git --no-verify` flag.

spdk_reactor_get_tsc_stats was added to return interesting statistics for each

reactor.

### IOAT

Change the return type of spdk_file_truncate from void to int. The purpose is to catch

the `NOMEM` error condition.

### DPDK 18.05

The DPDK submodule has been rebased on the DPDK 18.05 release.  DPDK 18.05 supports

dynamic memory allocation, but due to some issues found after the DPDK 18.05 release,

that support is not enabled for SPDK 18.07.  Therefore, SPDK 18.07 will continue to use

the legacy memory allocation model.  The plan is to enable dynamic memory allocation

after the DPDK 18.08 release which should fix these issues.

## v18.04: Logical Volume Snapshot/Clone, iSCSI Initiator, Bdev QoS, VPP Userspace TCP/IP

### vhost