Merge tag 'stable/for-linus-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm

Pull cleancache changes from Konrad Rzeszutek Wilk:
 "This has some patches for the cleancache API that should have been
  submitted a _long_ time ago.  They are basically cleanups:

   - rename of flush to invalidate

   - moving reporting of statistics into debugfs

   - use __read_mostly as necessary.

  Oh, and also the MAINTAINERS file change.  The files (except the
  MAINTAINERS file) have been in #linux-next for months now.  The late
  addition of MAINTAINERS file is a brain-fart on my side - didn't
  realize I needed that just until I was typing this up - and I based
  that patch on v3.3 - so the tree is on top of v3.3."

* tag 'stable/for-linus-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/mm:
  MAINTAINERS: Adding cleancache API to the list.
  mm: cleancache: Use __read_mostly as appropiate.
  mm: cleancache: report statistics via debugfs instead of sysfs.
  mm: zcache/tmem/cleancache: s/flush/invalidate/
  mm: cleancache: s/flush/invalidate/

3 files changed, 44 insertions, 66 deletions

diff --git a/mm/cleancache.c b/mm/cleancache.c
index bcaae4c2a770..5646c740f613 100644
--- a/mm/cleancache.c
+++ b/mm/cleancache.c
@@ -15,29 +15,34 @@
 #include <linux/fs.h>
 #include <linux/exportfs.h>
 #include <linux/mm.h>
+#include <linux/debugfs.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
+ * by cleancache_get/put/invalidate 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;
+int cleancache_enabled __read_mostly;
 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;
+static struct cleancache_ops cleancache_ops __read_mostly;
 
-/* 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;
+/*
+ * Counters available via /sys/kernel/debug/frontswap (if debugfs is
+ * properly configured.  These are for information only so are not protected
+ * against increment races.
+ */
+static u64 cleancache_succ_gets;
+static u64 cleancache_failed_gets;
+static u64 cleancache_puts;
+static u64 cleancache_invalidates;
 
 /*
  * register operations for cleancache, returning previous thus allowing
@@ -148,10 +153,11 @@ void __cleancache_put_page(struct page *page)
 EXPORT_SYMBOL(__cleancache_put_page);
 
 /*
- * Flush any data from cleancache associated with the poolid and the
+ * Invalidate 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)
+void __cleancache_invalidate_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;
@@ -160,85 +166,57 @@ void __cleancache_flush_page(struct address_space *mapping, struct page *page)
         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++;
+                        (*cleancache_ops.invalidate_page)(pool_id,
+                                                          key, page->index);
+                        cleancache_invalidates++;
                 }
         }
 }
-EXPORT_SYMBOL(__cleancache_flush_page);
+EXPORT_SYMBOL(__cleancache_invalidate_page);
 
 /*
- * Flush all data from cleancache associated with the poolid and the
+ * Invalidate 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)
+void __cleancache_invalidate_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);
+                (*cleancache_ops.invalidate_inode)(pool_id, key);
 }
-EXPORT_SYMBOL(__cleancache_flush_inode);
+EXPORT_SYMBOL(__cleancache_invalidate_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)
+void __cleancache_invalidate_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);
+                (*cleancache_ops.invalidate_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 */
+EXPORT_SYMBOL(__cleancache_invalidate_fs);
 
 static int __init init_cleancache(void)
 {
-#ifdef CONFIG_SYSFS
-        int err;
-
-        err = sysfs_create_group(mm_kobj, &cleancache_attr_group);
-#endif /* CONFIG_SYSFS */
+#ifdef CONFIG_DEBUG_FS
+        struct dentry *root = debugfs_create_dir("cleancache", NULL);
+        if (root == NULL)
+                return -ENXIO;
+        debugfs_create_u64("succ_gets", S_IRUGO, root, &cleancache_succ_gets);
+        debugfs_create_u64("failed_gets", S_IRUGO,
+                                root, &cleancache_failed_gets);
+        debugfs_create_u64("puts", S_IRUGO, root, &cleancache_puts);
+        debugfs_create_u64("invalidates", S_IRUGO,
+                                root, &cleancache_invalidates);
+#endif
         return 0;
 }
 module_init(init_cleancache)
diff --git a/mm/filemap.c b/mm/filemap.c
index 843042045dc9..c3811bc6b9e3 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -122,7 +122,7 @@ void __delete_from_page_cache(struct page *page)
         if (PageUptodate(page) && PageMappedToDisk(page))
                 cleancache_put_page(page);
         else
-                cleancache_flush_page(mapping, page);
+                cleancache_invalidate_page(mapping, page);
 
         radix_tree_delete(&mapping->page_tree, page->index);
         page->mapping = NULL;
diff --git a/mm/truncate.c b/mm/truncate.c
index a188058582e0..18aded3a89fc 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -52,7 +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);
+        cleancache_invalidate_page(page->mapping, page);
         if (page_has_private(page))
                 do_invalidatepage(page, partial);
 }
@@ -213,7 +213,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
         pgoff_t end;
         int i;
 
-        cleancache_flush_inode(mapping);
+        cleancache_invalidate_inode(mapping);
         if (mapping->nrpages == 0)
                 return;
 
@@ -292,7 +292,7 @@ void truncate_inode_pages_range(struct address_space *mapping,
                 mem_cgroup_uncharge_end();
                 index++;
         }
-        cleancache_flush_inode(mapping);
+        cleancache_invalidate_inode(mapping);
 }
 EXPORT_SYMBOL(truncate_inode_pages_range);
 
@@ -444,7 +444,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
         int ret2 = 0;
         int did_range_unmap = 0;
 
-        cleancache_flush_inode(mapping);
+        cleancache_invalidate_inode(mapping);
         pagevec_init(&pvec, 0);
         index = start;
         while (index <= end && pagevec_lookup(&pvec, mapping, index,
@@ -500,7 +500,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
                 cond_resched();
                 index++;
         }
-        cleancache_flush_inode(mapping);
+        cleancache_invalidate_inode(mapping);
         return ret;
 }
 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);