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: jeremy@goop.org: simplify init hook and any future fs init changes]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Reviewed-by: Jeremy Fitzhardinge <jeremy@goop.org>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rik Van Riel <riel@redhat.com>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: Andreas Dilger <adilger@sun.com>
Cc: Ted Ts'o <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Nitin Gupta <ngupta@vflare.org>

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index ba41da59e31b1d93348622d7b47655234f5ff930..0cee46e0108192e123b7a2d474d3bed66c3a9cbf 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -10,6 +10,7 @@
 #include <linux/swap.h>
 #include <linux/writeback.h>
 #include <linux/pagevec.h>
+#include <linux/cleancache.h>
 #include "extent_io.h"
 #include "extent_map.h"
 #include "compat.h"
@@ -2015,6 +2016,13 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
 
        set_page_extent_mapped(page);
 
+       if (!PageUptodate(page)) {
+               if (cleancache_get_page(page) == 0) {
+                       BUG_ON(blocksize != PAGE_SIZE);
+                       goto out;
+               }
+       }
+
        end = page_end;
        while (1) {
                lock_extent(tree, start, end, GFP_NOFS);
@@ -2148,6 +2156,7 @@ static int __extent_read_full_page(struct extent_io_tree *tree,
                cur = cur + iosize;
                page_offset += iosize;
        }
+out:
        if (!nr) {
                if (!PageError(page))
                        SetPageUptodate(page);

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 0ac712efcdf293ac8e858fef443b57316b039037..be4ffa12f3ef98ea1227a0d24c039bf6b6f1546d 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -39,6 +39,7 @@
 #include <linux/miscdevice.h>
 #include <linux/magic.h>
 #include <linux/slab.h>
+#include <linux/cleancache.h>
 #include "compat.h"
 #include "ctree.h"
 #include "disk-io.h"
@@ -624,6 +625,7 @@ static int btrfs_fill_super(struct super_block *sb,
        sb->s_root = root_dentry;
 
        save_mount_options(sb, data);
+       cleancache_init_fs(sb);
        return 0;
 
 fail_close: