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David Howells 16f2f4e679 nfs: Implement cache I/O by accessing the cache directly
Move NFS to using fscache DIO API instead of the old upstream I/O API as
that has been removed.  This is a stopgap solution as the intention is that
at sometime in the future, the cache will move to using larger blocks and
won't be able to store individual pages in order to deal with the potential
for data corruption due to the backing filesystem being able insert/remove
bridging blocks of zeros into its extent list[1].

NFS then reads and writes cache pages synchronously and one page at a time.

The preferred change would be to use the netfs lib, but the new I/O API can
be used directly.  It's just that as the cache now needs to track data for
itself, caching blocks may exceed page size...

This code is somewhat borrowed from my "fallback I/O" patchset[2].

Changes
=======
ver #3:
 - Restore lost =n fallback for nfs_fscache_release_page()[2].

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
cc: Trond Myklebust <trond.myklebust@hammerspace.com>
cc: Anna Schumaker <anna.schumaker@netapp.com>
cc: linux-nfs@vger.kernel.org
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/YO17ZNOcq+9PajfQ@mit.edu [1]
Link: https://lore.kernel.org/r/202112100957.2oEDT20W-lkp@intel.com/ [2]
Link: https://lore.kernel.org/r/163189108292.2509237.12615909591150927232.stgit@warthog.procyon.org.uk/ [2]
Link: https://lore.kernel.org/r/163906981318.143852.17220018647843475985.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967184451.1823006.6450645559828329590.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021577632.640689.11069627070150063812.stgit@warthog.procyon.org.uk/ # v4
2022-01-10 11:53:25 +00:00
arch parisc architecture bug and warning fixes for kernel v5.16-rc4 2021-12-05 12:58:18 -08:00
block block: call rq_qos_done() before ref check in batch completions 2021-11-26 09:53:23 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
Documentation Power management fixes for 5.16-rc4 2021-12-03 12:22:56 -08:00
drivers parisc architecture bug and warning fixes for kernel v5.16-rc4 2021-12-05 12:58:18 -08:00
fs nfs: Implement cache I/O by accessing the cache directly 2022-01-10 11:53:25 +00:00
include nfs: Implement cache I/O by accessing the cache directly 2022-01-10 11:53:25 +00:00
init kbuild: Fix -Wimplicit-fallthrough=5 error for GCC 5.x and 6.x 2021-11-14 18:59:49 -08:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-11-20 10:35:54 -08:00
kernel - Prevent a tick storm when a dedicated timekeeper CPU in nohz_full 2021-12-05 08:58:52 -08:00
lib siphash: use _unaligned version by default 2021-11-29 19:50:50 -08:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm Fixes for 5.16 folios: 2021-11-25 10:13:56 -08:00
net Networking fixes for 5.16-rc4, including fixes from wireless, 2021-12-02 11:22:06 -08:00
samples s390 updates for 5.16-rc2 2021-11-20 10:55:50 -08:00
scripts Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid 2021-11-24 09:44:13 -08:00
security selinux: fix NULL-pointer dereference when hashtab allocation fails 2021-11-19 16:11:39 -05:00
sound sound fixes for 5.16-rc4 2021-12-01 10:07:39 -08:00
tools - Fix a couple of SWAPGS fencing issues in the x86 entry code 2021-12-05 08:43:35 -08:00
usr initramfs: Check timestamp to prevent broken cpio archive 2021-10-24 13:48:40 +09:00
virt KVM: downgrade two BUG_ONs to WARN_ON_ONCE 2021-11-26 06:43:28 -05:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap MAINTAINERS: update email address of Christian Borntraeger 2021-11-18 17:50:54 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS TTY/Serial fixes for 5.16-rc4 2021-12-05 09:13:20 -08:00
Makefile Linux 5.16-rc4 2021-12-05 14:08:22 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.