mm/cleancache.c - linux/kernel/git/davem/net-next - Git at Google

 /*
  * 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)
	/*
	* 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)