4e260a8fd7
Provide cifs_splice_read() to use a bvec rather than an pipe iterator as
the latter cannot so easily be split and advanced, which is necessary to
pass an iterator down to the bottom levels. Upstream cifs gets around this
problem by using iov_iter_get_pages() to prefill the pipe and then passing
the list of pages down.
This is done by:
(1) Bulk-allocate a bunch of pages to carry as much of the requested
amount of data as possible, but without overrunning the available
slots in the pipe and add them to an ITER_BVEC.
(2) Synchronously call ->read_iter() to read into the buffer.
(3) Discard any unused pages.
(4) Load the remaining pages into the pipe in order and advance the head
pointer.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <nspmangalore@gmail.com>
cc: Rohith Surabattula <rohiths.msft@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: linux-cifs@vger.kernel.org
Link: https://lore.kernel.org/r/166732028113.3186319.1793644937097301358.stgit@warthog.procyon.org.uk/ # rfc
Signed-off-by: Steve French <stfrench@microsoft.com>
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.