linux/fs/cachefiles
David Howells 26aaeffcaf fscache, cachefiles: Add alternate API to use kiocb for read/write to cache
Add an alternate API by which the cache can be accessed through a kiocb,
doing async DIO, rather than using the current API that tells the cache
where all the pages are.

The new API is intended to be used in conjunction with the netfs helper
library.  A filesystem must pick one or the other and not mix them.

Filesystems wanting to use the new API must #define FSCACHE_USE_NEW_IO_API
before #including the header.  This prevents them from continuing to use
the old API at the same time as there are incompatibilities in how the
PG_fscache page bit is used.

Changes:
v6:
 - Provide a routine to shape a write so that the start and length can be
   aligned for DIO[3].

v4:
 - Use the vfs_iocb_iter_read/write() helpers[1]
 - Move initial definition of fscache_begin_read_operation() here.
 - Remove a commented-out line[2]
 - Combine ki->term_func calls in cachefiles_read_complete()[2].
 - Remove explicit NULL initialiser[2].
 - Remove extern on func decl[2].
 - Put in param names on func decl[2].
 - Remove redundant else[2].
 - Fill out the kdoc comment for fscache_begin_read_operation().
 - Rename fs/fscache/page2.c to io.c to match later patches.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-and-tested-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Tested-By: Marc Dionne <marc.dionne@auristor.com>
cc: Christoph Hellwig <hch@lst.de>
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20210216102614.GA27555@lst.de/ [1]
Link: https://lore.kernel.org/r/20210216084230.GA23669@lst.de/ [2]
Link: https://lore.kernel.org/r/161781047695.463527.7463536103593997492.stgit@warthog.procyon.org.uk/ [3]
Link: https://lore.kernel.org/r/161118142558.1232039.17993829899588971439.stgit@warthog.procyon.org.uk/ # rfc
Link: https://lore.kernel.org/r/161161037850.2537118.8819808229350326503.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/161340402057.1303470.8038373593844486698.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/161539545919.286939.14573472672781434757.stgit@warthog.procyon.org.uk/ # v4
Link: https://lore.kernel.org/r/161653801477.2770958.10543270629064934227.stgit@warthog.procyon.org.uk/ # v5
Link: https://lore.kernel.org/r/161789084517.6155.12799689829859169640.stgit@warthog.procyon.org.uk/ # v6
2021-04-23 10:14:32 +01:00
..
bind.c cachefiles: do not yet allow on idmapped mounts 2021-03-24 10:20:22 -07:00
daemon.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
interface.c fscache, cachefiles: Add alternate API to use kiocb for read/write to cache 2021-04-23 10:14:32 +01:00
internal.h fscache, cachefiles: Add alternate API to use kiocb for read/write to cache 2021-04-23 10:14:32 +01:00
io.c fscache, cachefiles: Add alternate API to use kiocb for read/write to cache 2021-04-23 10:14:32 +01:00
Kconfig docs: filesystems: caching/cachefiles.txt: convert to ReST 2020-05-05 09:22:21 -06:00
key.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
main.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
Makefile fscache, cachefiles: Add alternate API to use kiocb for read/write to cache 2021-04-23 10:14:32 +01:00
namei.c namei: prepare for idmapped mounts 2021-01-24 14:27:18 +01:00
proc.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
rdwr.c fs/cachefiles: Remove wait_bit_key layout dependency 2021-03-23 20:54:29 +00:00
security.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
xattr.c xattr: handle idmapped mounts 2021-01-24 14:27:17 +01:00