linux/fs/cachefiles
David Howells 1f08c925e7 cachefiles: Implement backing file wrangling
Implement the wrangling of backing files, including the following pieces:

 (1) Lookup and creation of a file on disk, using a tmpfile if the file
     isn't yet present.  The file is then opened, sized for DIO and the
     file handle is attached to the cachefiles_object struct.  The inode is
     marked to indicate that it's in use by a kernel service.

 (2) Invalidation of an object, creating a tmpfile and switching the file
     pointer in the cachefiles object.

 (3) Committing a file to disk, including setting the coherency xattr on it
     and, if necessary, creating a hard link to it.

     Note that this would be a good place to use Omar Sandoval's vfs_link()
     with AT_LINK_REPLACE[1] as I may have to unlink an old file before I
     can link a tmpfile into place.

 (4) Withdrawal of open objects when a cache is being withdrawn or a cookie
     is relinquished.  This involves committing or discarding the file.

Changes
=======
ver #2:
 - Fix logging of wrong error[1].

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/20211203094950.GA2480@kili/ [1]
Link: https://lore.kernel.org/r/163819644097.215744.4505389616742411239.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906949512.143852.14222856795032602080.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967158526.1823006.17482695321424642675.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021557060.640689.16373541458119269871.stgit@warthog.procyon.org.uk/ # v4
2022-01-07 13:42:40 +00:00
..
cache.c cachefiles: Implement backing file wrangling 2022-01-07 13:42:40 +00:00
daemon.c cachefiles: Implement backing file wrangling 2022-01-07 13:42:40 +00:00
error_inject.c cachefiles: Add some error injection support 2022-01-07 13:40:56 +00:00
interface.c cachefiles: Implement backing file wrangling 2022-01-07 13:42:40 +00:00
internal.h cachefiles: Implement backing file wrangling 2022-01-07 13:42:40 +00:00
Kconfig cachefiles: Add some error injection support 2022-01-07 13:40:56 +00:00
key.c cachefiles: Implement key to filename encoding 2022-01-07 13:42:16 +00:00
main.c cachefiles: Implement object lifecycle funcs 2022-01-07 13:42:08 +00:00
Makefile cachefiles: Implement metadata/coherency data storage in xattrs 2022-01-07 13:42:24 +00:00
namei.c cachefiles: Implement backing file wrangling 2022-01-07 13:42:40 +00:00
security.c cachefiles: Add security derivation 2022-01-07 13:41:14 +00:00
volume.c cachefiles: Implement volume support 2022-01-07 13:41:53 +00:00
xattr.c cachefiles: Implement metadata/coherency data storage in xattrs 2022-01-07 13:42:24 +00:00