5 files changed, 285 insertions, 0 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index e9c0c61f2dd..8ca47a5ee9c 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -347,3 +347,26 @@ config NEED_PER_CPU_KM
         depends on !SMP
         bool
         default y
+
+config CLEANCACHE
+        bool "Enable cleancache driver to cache clean pages if tmem is present"
+        default n
+        help
+          Cleancache can be thought of as a page-granularity victim cache
+          for clean pages that the kernel's pageframe replacement algorithm
+          (PFRA) would like to keep around, but can't since there isn't enough
+          memory.  So when the PFRA "evicts" a page, it first attempts to use
+          cleancacne code to put the data contained in that page into
+          "transcendent memory", memory that is not directly accessible or
+          addressable by the kernel and is of unknown and possibly
+          time-varying size.  And when a cleancache-enabled
+          filesystem wishes to access a page in a file on disk, it first
+          checks cleancache to see if it already contains it; if it does,
+          the page is copied into the kernel and a disk access is avoided.
+          When a transcendent memory driver is available (such as zcache or
+          Xen transcendent memory), a significant I/O reduction
+          may be achieved.  When none is available, all cleancache calls
+          are reduced to a single pointer-compare-against-NULL resulting
+          in a negligible performance hit.
+
+          If unsure, say Y to enable cleancache
diff --git a/mm/Makefile b/mm/Makefile
index 42a8326c3e3..836e4163c1b 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -49,3 +49,4 @@ obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o
 obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o
 obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
 obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
+obj-$(CONFIG_CLEANCACHE) += cleancache.o
diff --git a/mm/cleancache.c b/mm/cleancache.c
new file mode 100644
index 00000000000..bcaae4c2a77
--- /dev/null
+++ b/mm/cleancache.c
@@ -0,0 +1,244 @@
+/*
+ * Cleancache frontend
+ *
+ * This code provides the generic "frontend" layer to call a matching
+ * "backend" driver implementation of cleancache.  See
+ * Documentation/vm/cleancache.txt for more information.
+ *
+ * Copyright (C) 2009-2010 Oracle Corp. All rights reserved.
+ * Author: Dan Magenheimer
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/exportfs.h>
+#include <linux/mm.h>
+#include <linux/cleancache.h>
+
+/*
+ * This global enablement flag may be read thousands of times per second
+ * by cleancache_get/put/flush even on systems where cleancache_ops
+ * is not claimed (e.g. cleancache is config'ed on but remains
+ * disabled), so is preferred to the slower alternative: a function
+ * call that checks a non-global.
+ */
+int cleancache_enabled;
+EXPORT_SYMBOL(cleancache_enabled);
+
+/*
+ * cleancache_ops is set by cleancache_ops_register to contain the pointers
+ * to the cleancache "backend" implementation functions.
+ */
+static struct cleancache_ops cleancache_ops;
+
+/* useful stats available in /sys/kernel/mm/cleancache */
+static unsigned long cleancache_succ_gets;
+static unsigned long cleancache_failed_gets;
+static unsigned long cleancache_puts;
+static unsigned long cleancache_flushes;
+
+/*
+ * register operations for cleancache, returning previous thus allowing
+ * detection of multiple backends and possible nesting
+ */
+struct cleancache_ops cleancache_register_ops(struct cleancache_ops *ops)
+{
+        struct cleancache_ops old = cleancache_ops;
+
+        cleancache_ops = *ops;
+        cleancache_enabled = 1;
+        return old;
+}
+EXPORT_SYMBOL(cleancache_register_ops);
+
+/* Called by a cleancache-enabled filesystem at time of mount */
+void __cleancache_init_fs(struct super_block *sb)
+{
+        sb->cleancache_poolid = (*cleancache_ops.init_fs)(PAGE_SIZE);
+}
+EXPORT_SYMBOL(__cleancache_init_fs);
+
+/* Called by a cleancache-enabled clustered filesystem at time of mount */
+void __cleancache_init_shared_fs(char *uuid, struct super_block *sb)
+{
+        sb->cleancache_poolid =
+                (*cleancache_ops.init_shared_fs)(uuid, PAGE_SIZE);
+}
+EXPORT_SYMBOL(__cleancache_init_shared_fs);
+
+/*
+ * If the filesystem uses exportable filehandles, use the filehandle as
+ * the key, else use the inode number.
+ */
+static int cleancache_get_key(struct inode *inode,
+                              struct cleancache_filekey *key)
+{
+        int (*fhfn)(struct dentry *, __u32 *fh, int *, int);
+        int len = 0, maxlen = CLEANCACHE_KEY_MAX;
+        struct super_block *sb = inode->i_sb;
+
+        key->u.ino = inode->i_ino;
+        if (sb->s_export_op != NULL) {
+                fhfn = sb->s_export_op->encode_fh;
+                if  (fhfn) {
+                        struct dentry d;
+                        d.d_inode = inode;
+                        len = (*fhfn)(&d, &key->u.fh[0], &maxlen, 0);
+                        if (len <= 0 || len == 255)
+                                return -1;
+                        if (maxlen > CLEANCACHE_KEY_MAX)
+                                return -1;
+                }
+        }
+        return 0;
+}
+
+/*
+ * "Get" data from cleancache associated with the poolid/inode/index
+ * that were specified when the data was put to cleanache and, if
+ * successful, use it to fill the specified page with data and return 0.
+ * The pageframe is unchanged and returns -1 if the get fails.
+ * Page must be locked by caller.
+ */
+int __cleancache_get_page(struct page *page)
+{
+        int ret = -1;
+        int pool_id;
+        struct cleancache_filekey key = { .u.key = { 0 } };
+
+        VM_BUG_ON(!PageLocked(page));
+        pool_id = page->mapping->host->i_sb->cleancache_poolid;
+        if (pool_id < 0)
+                goto out;
+
+        if (cleancache_get_key(page->mapping->host, &key) < 0)
+                goto out;
+
+        ret = (*cleancache_ops.get_page)(pool_id, key, page->index, page);
+        if (ret == 0)
+                cleancache_succ_gets++;
+        else
+                cleancache_failed_gets++;
+out:
+        return ret;
+}
+EXPORT_SYMBOL(__cleancache_get_page);
+
+/*
+ * "Put" data from a page to cleancache and associate it with the
+ * (previously-obtained per-filesystem) poolid and the page's,
+ * inode and page index.  Page must be locked.  Note that a put_page
+ * always "succeeds", though a subsequent get_page may succeed or fail.
+ */
+void __cleancache_put_page(struct page *page)
+{
+        int pool_id;
+        struct cleancache_filekey key = { .u.key = { 0 } };
+
+        VM_BUG_ON(!PageLocked(page));
+        pool_id = page->mapping->host->i_sb->cleancache_poolid;
+        if (pool_id >= 0 &&
+              cleancache_get_key(page->mapping->host, &key) >= 0) {
+                (*cleancache_ops.put_page)(pool_id, key, page->index, page);
+                cleancache_puts++;
+        }
+}
+EXPORT_SYMBOL(__cleancache_put_page);
+
+/*
+ * Flush any data from cleancache associated with the poolid and the
+ * page's inode and page index so that a subsequent "get" will fail.
+ */
+void __cleancache_flush_page(struct address_space *mapping, struct page *page)
+{
+        /* careful... page->mapping is NULL sometimes when this is called */
+        int pool_id = mapping->host->i_sb->cleancache_poolid;
+        struct cleancache_filekey key = { .u.key = { 0 } };
+
+        if (pool_id >= 0) {
+                VM_BUG_ON(!PageLocked(page));
+                if (cleancache_get_key(mapping->host, &key) >= 0) {
+                        (*cleancache_ops.flush_page)(pool_id, key, page->index);
+                        cleancache_flushes++;
+                }
+        }
+}
+EXPORT_SYMBOL(__cleancache_flush_page);
+
+/*
+ * Flush all data from cleancache associated with the poolid and the
+ * mappings's inode so that all subsequent gets to this poolid/inode
+ * will fail.
+ */
+void __cleancache_flush_inode(struct address_space *mapping)
+{
+        int pool_id = mapping->host->i_sb->cleancache_poolid;
+        struct cleancache_filekey key = { .u.key = { 0 } };
+
+        if (pool_id >= 0 && cleancache_get_key(mapping->host, &key) >= 0)
+                (*cleancache_ops.flush_inode)(pool_id, key);
+}
+EXPORT_SYMBOL(__cleancache_flush_inode);
+
+/*
+ * Called by any cleancache-enabled filesystem at time of unmount;
+ * note that pool_id is surrendered and may be reutrned by a subsequent
+ * cleancache_init_fs or cleancache_init_shared_fs
+ */
+void __cleancache_flush_fs(struct super_block *sb)
+{
+        if (sb->cleancache_poolid >= 0) {
+                int old_poolid = sb->cleancache_poolid;
+                sb->cleancache_poolid = -1;
+                (*cleancache_ops.flush_fs)(old_poolid);
+        }
+}
+EXPORT_SYMBOL(__cleancache_flush_fs);
+
+#ifdef CONFIG_SYSFS
+
+/* see Documentation/ABI/xxx/sysfs-kernel-mm-cleancache */
+
+#define CLEANCACHE_SYSFS_RO(_name) \
+        static ssize_t cleancache_##_name##_show(struct kobject *kobj, \
+                                struct kobj_attribute *attr, char *buf) \
+        { \
+                return sprintf(buf, "%lu\n", cleancache_##_name); \
+        } \
+        static struct kobj_attribute cleancache_##_name##_attr = { \
+                .attr = { .name = __stringify(_name), .mode = 0444 }, \
+                .show = cleancache_##_name##_show, \
+        }
+
+CLEANCACHE_SYSFS_RO(succ_gets);
+CLEANCACHE_SYSFS_RO(failed_gets);
+CLEANCACHE_SYSFS_RO(puts);
+CLEANCACHE_SYSFS_RO(flushes);
+
+static struct attribute *cleancache_attrs[] = {
+        &cleancache_succ_gets_attr.attr,
+        &cleancache_failed_gets_attr.attr,
+        &cleancache_puts_attr.attr,
+        &cleancache_flushes_attr.attr,
+        NULL,
+};
+
+static struct attribute_group cleancache_attr_group = {
+        .attrs = cleancache_attrs,
+        .name = "cleancache",
+};
+
+#endif /* CONFIG_SYSFS */
+
+static int __init init_cleancache(void)
+{
+#ifdef CONFIG_SYSFS
+        int err;
+
+        err = sysfs_create_group(mm_kobj, &cleancache_attr_group);
+#endif /* CONFIG_SYSFS */
+        return 0;
+}
+module_init(init_cleancache)
diff --git a/mm/filemap.c b/mm/filemap.c
index 68e782b3d3d..7455ccd8bda 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -34,6 +34,7 @@
 #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
 #include <linux/memcontrol.h>
 #include <linux/mm_inline.h> /* for page_is_file_cache() */
+#include <linux/cleancache.h>
 #include "internal.h"
 
 /*
@@ -118,6 +119,16 @@ void __delete_from_page_cache(struct page *page)
 {
         struct address_space *mapping = page->mapping;
 
+        /*
+         * if we're uptodate, flush out into the cleancache, otherwise
+         * invalidate any existing cleancache entries.  We can't leave
+         * stale data around in the cleancache once our page is gone
+         */
+        if (PageUptodate(page) && PageMappedToDisk(page))
+                cleancache_put_page(page);
+        else
+                cleancache_flush_page(mapping, page);
+
         radix_tree_delete(&mapping->page_tree, page->index);
         page->mapping = NULL;
         mapping->nrpages--;
diff --git a/mm/truncate.c b/mm/truncate.c
index a9566752913..3a29a618021 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -19,6 +19,7 @@
 #include <linux/task_io_accounting_ops.h>
 #include <linux/buffer_head.h>  /* grr. try_to_release_page,
                                    do_invalidatepage */
+#include <linux/cleancache.h>
 #include "internal.h"
 
 
@@ -51,6 +52,7 @@ void do_invalidatepage(struct page *page, unsigned long offset)
 static inline void truncate_partial_page(struct page *page, unsigned partial)
 {
         zero_user_segment(page, partial, PAGE_CACHE_SIZE);
+        cleancache_flush_page(page->mapping, page);
         if (page_has_private(page))
                 do_invalidatepage(page, partial);
 }
@@ -214,6 +216,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
         pgoff_t next;
         int i;
 
+        cleancache_flush_inode(mapping);
         if (mapping->nrpages == 0)
                 return;
 
@@ -291,6 +294,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
                 pagevec_release(&pvec);
                 mem_cgroup_uncharge_end();
         }
+        cleancache_flush_inode(mapping);
 }
 EXPORT_SYMBOL(truncate_inode_pages_range);
 
@@ -440,6 +444,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
         int did_range_unmap = 0;
         int wrapped = 0;
 
+        cleancache_flush_inode(mapping);
         pagevec_init(&pvec, 0);
         next = start;
         while (next <= end && !wrapped &&
@@ -498,6 +503,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
                 mem_cgroup_uncharge_end();
                 cond_resched();
         }
+        cleancache_flush_inode(mapping);
         return ret;
 }
 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);