mm/cleancache.c - third_party/linux - 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/debugfs.h>
 #include <linux/cleancache.h>

 /*
  * This global enablement flag may be read thousands of times per second
  * 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 __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 __read_mostly;

 /*
  * 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
  * 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 inode *, __u32 *fh, int *, struct inode *);
 	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) {
 			len = (*fhfn)(inode, &key->u.fh[0], &maxlen, NULL);
 			if (len <= FILEID_ROOT || len == FILEID_INVALID)
 				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);

 /*
  * 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_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;
 	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.invalidate_page)(pool_id,
 							  key, page->index);
 			cleancache_invalidates++;
 		}
 	}
 }
 EXPORT_SYMBOL(__cleancache_invalidate_page);

 /*
  * 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_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.invalidate_inode)(pool_id, key);
 }
 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_invalidate_fs(struct super_block *sb)
 {
 	if (sb->cleancache_poolid >= 0) {
 		int old_poolid = sb->cleancache_poolid;
 		sb->cleancache_poolid = -1;
 		(*cleancache_ops.invalidate_fs)(old_poolid);
 	}
 }
 EXPORT_SYMBOL(__cleancache_invalidate_fs);

 static int __init init_cleancache(void)
 {
 #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)
	/*
	* 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/debugfs.h>
	#include <linux/cleancache.h>

	/*
	* This global enablement flag may be read thousands of times per second
	* 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 __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 __read_mostly;

	/*
	* 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
	* 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 inode , __u32 fh, int , struct inode *);
	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) {
	len = (*fhfn)(inode, &key->u.fh[0], &maxlen, NULL);
	if (len <= FILEID_ROOT \|\| len == FILEID_INVALID)
	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);

	/*
	* 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_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;
	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.invalidate_page)(pool_id,
	key, page->index);
	cleancache_invalidates++;
	}
	}
	}
	EXPORT_SYMBOL(__cleancache_invalidate_page);

	/*
	* 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_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.invalidate_inode)(pool_id, key);
	}
	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_invalidate_fs(struct super_block *sb)
	{
	if (sb->cleancache_poolid >= 0) {
	int old_poolid = sb->cleancache_poolid;
	sb->cleancache_poolid = -1;
	(*cleancache_ops.invalidate_fs)(old_poolid);
	}
	}
	EXPORT_SYMBOL(__cleancache_invalidate_fs);

	static int __init init_cleancache(void)
	{
	#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)