btrfs: add cleancache support

This sixth patch of eight in this cleancache series "opts-in"
cleancache for btrfs.  Filesystems must explicitly enable
cleancache by calling cleancache_init_fs anytime an instance
of the filesystem is mounted.  Btrfs uses its own readpage
which must be hooked, but all other cleancache hooks are in
the VFS layer including the matching cleancache_flush_fs hook
which must be called on unmount.

Details and a FAQ can be found in Documentation/vm/cleancache.txt

[v6-v8: no changes]
[v5: [email protected]: simplify init hook and any future fs init changes]
Signed-off-by: Dan Magenheimer <[email protected]>
Signed-off-by: Chris Mason <[email protected]>
Reviewed-by: Jeremy Fitzhardinge <[email protected]>
Reviewed-by: Konrad Rzeszutek Wilk <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Nick Piggin <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Rik Van Riel <[email protected]>
Cc: Jan Beulich <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Ted Ts'o <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Nitin Gupta <[email protected]>

0 files changed, 0 insertions, 0 deletions