Chaitanya Kulkarni 39dfe84451 nvme: split nvme_alloc_request()
Right now nvme_alloc_request() allocates a request from block layer
based on the value of the qid. When qid set to NVME_QID_ANY it used
blk_mq_alloc_request() else blk_mq_alloc_request_hctx().

The function nvme_alloc_request() is called from different context, The
only place where it uses non NVME_QID_ANY value is for fabrics connect
commands :-

nvme_submit_sync_cmd()		NVME_QID_ANY
nvme_features()			NVME_QID_ANY
nvme_sec_submit()		NVME_QID_ANY
nvmf_reg_read32()		NVME_QID_ANY
nvmf_reg_read64()		NVME_QID_ANY
nvmf_reg_write32()		NVME_QID_ANY
nvmf_connect_admin_queue()	NVME_QID_ANY
nvme_submit_user_cmd()		NVME_QID_ANY
	nvme_alloc_request()
nvme_keep_alive()		NVME_QID_ANY
	nvme_alloc_request()
nvme_timeout()			NVME_QID_ANY
	nvme_alloc_request()
nvme_delete_queue()		NVME_QID_ANY
	nvme_alloc_request()
nvmet_passthru_execute_cmd()	NVME_QID_ANY
	nvme_alloc_request()
nvmf_connect_io_queue() 	QID
	__nvme_submit_sync_cmd()
		nvme_alloc_request()

With passthru nvme_alloc_request() now falls into the I/O fast path such
that blk_mq_alloc_request_hctx() is never gets called and that adds
additional branch check in fast path.

Split the nvme_alloc_request() into nvme_alloc_request() and
nvme_alloc_request_qid().

Replace each call of the nvme_alloc_request() with NVME_QID_ANY param
with a call to newly added nvme_alloc_request() without NVME_QID_ANY.

Replace a call to nvme_alloc_request() with QID param with a call to
newly added nvme_alloc_request() and nvme_alloc_request_qid()
based on the qid value set in the __nvme_submit_sync_cmd().

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
2020-12-01 20:36:35 +01:00
2020-12-01 20:36:35 +01:00
2020-11-15 16:44:31 -08:00
…

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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