David Howells 5d00e426f9 fscache: Implement simple cookie state machine ... Implement a very simple cookie state machine to handle lookup, invalidation, withdrawal, relinquishment and, to be added later, commit on LRU discard. Three cache methods are provided: ->lookup_cookie() to look up and, if necessary, create a data storage object; ->withdraw_cookie() to free the resources associated with that object and potentially delete it; and ->prepare_to_write(), to do prepare for changes to the cached data to be modified locally. Changes ======= ver #3: - Fix a race between LRU discard and relinquishment whereby the former would override the latter and thus the latter would never happen[1]. ver #2: - Don't hold n_accesses elevated whilst cache is bound to a cookie, but rather add a flag that prevents the state machine from being queued when n_accesses reaches 0. 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/599331.1639410068@warthog.procyon.org.uk/ [1] Link: https://lore.kernel.org/r/163819599657.215744.15799615296912341745.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906903925.143852.1805855338154353867.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967105456.1823006.14730395299835841776.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021510706.640689.7961423370243272583.stgit@warthog.procyon.org.uk/ # v4		2022-01-07 09:22:19 +00:00
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cache.c	fscache: Add a function for a cache backend to note an I/O error	2022-01-07 09:22:19 +00:00
cookie.c	fscache: Implement simple cookie state machine	2022-01-07 09:22:19 +00:00
internal.h	fscache: Implement cookie-level access helpers	2022-01-07 09:22:19 +00:00
Kconfig	fscache: Introduce new driver	2022-01-07 09:22:19 +00:00
main.c	fscache: Implement cookie-level access helpers	2022-01-07 09:22:19 +00:00
Makefile	fscache: Implement cookie registration	2022-01-07 09:22:19 +00:00
proc.c	fscache: Implement cookie registration	2022-01-07 09:22:19 +00:00
stats.c	fscache: Implement cookie registration	2022-01-07 09:22:19 +00:00
volume.c	fscache: Provide and use cache methods to lookup/create/free a volume	2022-01-07 09:22:19 +00:00