mm/cleancache.c - kernel/msm-5.4 - Gitiles

 /*
  * Cleancache frontend
  *
  * This code provides the generic "frontend" layer to call a matching
  * "backend" driver implementation of cleancache.  See
  * Documentation/vm/cleancache.rst 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>

 /*
  * cleancache_ops is set by cleancache_register_ops to contain the pointers
  * to the cleancache "backend" implementation functions.
  */
 static const struct cleancache_ops *cleancache_ops __read_mostly;

 /*
  * Counters available via /sys/kernel/debug/cleancache (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;

 static void cleancache_register_ops_sb(struct super_block *sb, void *unused)
 {
 	switch (sb->cleancache_poolid) {
 	case CLEANCACHE_NO_BACKEND:
 		__cleancache_init_fs(sb);
 		break;
 	case CLEANCACHE_NO_BACKEND_SHARED:
 		__cleancache_init_shared_fs(sb);
 		break;
 	}
 }

 /*
  * Register operations for cleancache. Returns 0 on success.
  */
 int cleancache_register_ops(const struct cleancache_ops *ops)
 {
 	if (cmpxchg(&cleancache_ops, NULL, ops))
 		return -EBUSY;

 	/*
 	 * A cleancache backend can be built as a module and hence loaded after
 	 * a cleancache enabled filesystem has called cleancache_init_fs. To
 	 * handle such a scenario, here we call ->init_fs or ->init_shared_fs
 	 * for each active super block. To differentiate between local and
 	 * shared filesystems, we temporarily initialize sb->cleancache_poolid
 	 * to CLEANCACHE_NO_BACKEND or CLEANCACHE_NO_BACKEND_SHARED
 	 * respectively in case there is no backend registered at the time
 	 * cleancache_init_fs or cleancache_init_shared_fs is called.
 	 *
 	 * Since filesystems can be mounted concurrently with cleancache
 	 * backend registration, we have to be careful to guarantee that all
 	 * cleancache enabled filesystems that has been mounted by the time
 	 * cleancache_register_ops is called has got and all mounted later will
 	 * get cleancache_poolid. This is assured by the following statements
 	 * tied together:
 	 *
 	 * a) iterate_supers skips only those super blocks that has started
 	 *    ->kill_sb
 	 *
 	 * b) if iterate_supers encounters a super block that has not finished
 	 *    ->mount yet, it waits until it is finished
 	 *
 	 * c) cleancache_init_fs is called from ->mount and
 	 *    cleancache_invalidate_fs is called from ->kill_sb
 	 *
 	 * d) we call iterate_supers after cleancache_ops has been set
 	 *
 	 * From a) it follows that if iterate_supers skips a super block, then
 	 * either the super block is already dead, in which case we do not need
 	 * to bother initializing cleancache for it, or it was mounted after we
 	 * initiated iterate_supers. In the latter case, it must have seen
 	 * cleancache_ops set according to d) and initialized cleancache from
 	 * ->mount by itself according to c). This proves that we call
 	 * ->init_fs at least once for each active super block.
 	 *
 	 * From b) and c) it follows that if iterate_supers encounters a super
 	 * block that has already started ->init_fs, it will wait until ->mount
 	 * and hence ->init_fs has finished, then check cleancache_poolid, see
 	 * that it has already been set and therefore do nothing. This proves
 	 * that we call ->init_fs no more than once for each super block.
 	 *
 	 * Combined together, the last two paragraphs prove the function
 	 * correctness.
 	 *
 	 * Note that various cleancache callbacks may proceed before this
 	 * function is called or even concurrently with it, but since
 	 * CLEANCACHE_NO_BACKEND is negative, they will all result in a noop
 	 * until the corresponding ->init_fs has been actually called and
 	 * cleancache_ops has been set.
 	 */
 	iterate_supers(cleancache_register_ops_sb, NULL);
 	return 0;
 }
 EXPORT_SYMBOL(cleancache_register_ops);

 /* Called by a cleancache-enabled filesystem at time of mount */
 void __cleancache_init_fs(struct super_block *sb)
 {
 	int pool_id = CLEANCACHE_NO_BACKEND;

 	if (cleancache_ops) {
 		pool_id = cleancache_ops->init_fs(PAGE_SIZE);
 		if (pool_id < 0)
 			pool_id = CLEANCACHE_NO_POOL;
 	}
 	sb->cleancache_poolid = pool_id;
 }
 EXPORT_SYMBOL(__cleancache_init_fs);

 /* Called by a cleancache-enabled clustered filesystem at time of mount */
 void __cleancache_init_shared_fs(struct super_block *sb)
 {
 	int pool_id = CLEANCACHE_NO_BACKEND_SHARED;

 	if (cleancache_ops) {
 		pool_id = cleancache_ops->init_shared_fs(&sb->s_uuid, PAGE_SIZE);
 		if (pool_id < 0)
 			pool_id = CLEANCACHE_NO_POOL;
 	}
 	sb->cleancache_poolid = pool_id;
 }
 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.
  *
  * The function has two checks before any action is taken - whether
  * a backend is registered and whether the sb->cleancache_poolid
  * is correct.
  */
 int __cleancache_get_page(struct page *page)
 {
 	int ret = -1;
 	int pool_id;
 	struct cleancache_filekey key = { .u.key = { 0 } };

 	if (!cleancache_ops) {
 		cleancache_failed_gets++;
 		goto out;
 	}

 	VM_BUG_ON_PAGE(!PageLocked(page), 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.
  *
  * The function has two checks before any action is taken - whether
  * a backend is registered and whether the sb->cleancache_poolid
  * is correct.
  */
 void __cleancache_put_page(struct page *page)
 {
 	int pool_id;
 	struct cleancache_filekey key = { .u.key = { 0 } };

 	if (!cleancache_ops) {
 		cleancache_puts++;
 		return;
 	}

 	VM_BUG_ON_PAGE(!PageLocked(page), 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.
  *
  * The function has two checks before any action is taken - whether
  * a backend is registered and whether the sb->cleancache_poolid
  * is correct.
  */
 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 (!cleancache_ops)
 		return;

 	if (pool_id >= 0) {
 		VM_BUG_ON_PAGE(!PageLocked(page), 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.
  *
  * The function has two checks before any action is taken - whether
  * a backend is registered and whether the sb->cleancache_poolid
  * is correct.
  */
 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 (!cleancache_ops)
 		return;

 	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 returned by a subsequent
  * cleancache_init_fs or cleancache_init_shared_fs.
  */
 void __cleancache_invalidate_fs(struct super_block *sb)
 {
 	int pool_id;

 	pool_id = sb->cleancache_poolid;
 	sb->cleancache_poolid = CLEANCACHE_NO_POOL;

 	if (cleancache_ops && pool_id >= 0)
 		cleancache_ops->invalidate_fs(pool_id);
 }
 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.rst 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>

	/*
	* cleancache_ops is set by cleancache_register_ops to contain the pointers
	* to the cleancache "backend" implementation functions.
	*/
	static const struct cleancache_ops *cleancache_ops __read_mostly;

	/*
	* Counters available via /sys/kernel/debug/cleancache (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;

	static void cleancache_register_ops_sb(struct super_block sb, void unused)
	{
	switch (sb->cleancache_poolid) {
	case CLEANCACHE_NO_BACKEND:
	__cleancache_init_fs(sb);
	break;
	case CLEANCACHE_NO_BACKEND_SHARED:
	__cleancache_init_shared_fs(sb);
	break;
	}
	}

	/*
	* Register operations for cleancache. Returns 0 on success.
	*/
	int cleancache_register_ops(const struct cleancache_ops *ops)
	{
	if (cmpxchg(&cleancache_ops, NULL, ops))
	return -EBUSY;

	/*
	* A cleancache backend can be built as a module and hence loaded after
	* a cleancache enabled filesystem has called cleancache_init_fs. To
	* handle such a scenario, here we call ->init_fs or ->init_shared_fs
	* for each active super block. To differentiate between local and
	* shared filesystems, we temporarily initialize sb->cleancache_poolid
	* to CLEANCACHE_NO_BACKEND or CLEANCACHE_NO_BACKEND_SHARED
	* respectively in case there is no backend registered at the time
	* cleancache_init_fs or cleancache_init_shared_fs is called.
	*
	* Since filesystems can be mounted concurrently with cleancache
	* backend registration, we have to be careful to guarantee that all
	* cleancache enabled filesystems that has been mounted by the time
	* cleancache_register_ops is called has got and all mounted later will
	* get cleancache_poolid. This is assured by the following statements
	* tied together:
	*
	* a) iterate_supers skips only those super blocks that has started
	* ->kill_sb
	*
	* b) if iterate_supers encounters a super block that has not finished
	* ->mount yet, it waits until it is finished
	*
	* c) cleancache_init_fs is called from ->mount and
	* cleancache_invalidate_fs is called from ->kill_sb
	*
	* d) we call iterate_supers after cleancache_ops has been set
	*
	* From a) it follows that if iterate_supers skips a super block, then
	* either the super block is already dead, in which case we do not need
	* to bother initializing cleancache for it, or it was mounted after we
	* initiated iterate_supers. In the latter case, it must have seen
	* cleancache_ops set according to d) and initialized cleancache from
	* ->mount by itself according to c). This proves that we call
	* ->init_fs at least once for each active super block.
	*
	* From b) and c) it follows that if iterate_supers encounters a super
	* block that has already started ->init_fs, it will wait until ->mount
	* and hence ->init_fs has finished, then check cleancache_poolid, see
	* that it has already been set and therefore do nothing. This proves
	* that we call ->init_fs no more than once for each super block.
	*
	* Combined together, the last two paragraphs prove the function
	* correctness.
	*
	* Note that various cleancache callbacks may proceed before this
	* function is called or even concurrently with it, but since
	* CLEANCACHE_NO_BACKEND is negative, they will all result in a noop
	* until the corresponding ->init_fs has been actually called and
	* cleancache_ops has been set.
	*/
	iterate_supers(cleancache_register_ops_sb, NULL);
	return 0;
	}
	EXPORT_SYMBOL(cleancache_register_ops);

	/* Called by a cleancache-enabled filesystem at time of mount */
	void __cleancache_init_fs(struct super_block *sb)
	{
	int pool_id = CLEANCACHE_NO_BACKEND;

	if (cleancache_ops) {
	pool_id = cleancache_ops->init_fs(PAGE_SIZE);
	if (pool_id < 0)
	pool_id = CLEANCACHE_NO_POOL;
	}
	sb->cleancache_poolid = pool_id;
	}
	EXPORT_SYMBOL(__cleancache_init_fs);

	/* Called by a cleancache-enabled clustered filesystem at time of mount */
	void __cleancache_init_shared_fs(struct super_block *sb)
	{
	int pool_id = CLEANCACHE_NO_BACKEND_SHARED;

	if (cleancache_ops) {
	pool_id = cleancache_ops->init_shared_fs(&sb->s_uuid, PAGE_SIZE);
	if (pool_id < 0)
	pool_id = CLEANCACHE_NO_POOL;
	}
	sb->cleancache_poolid = pool_id;
	}
	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.
	*
	* The function has two checks before any action is taken - whether
	* a backend is registered and whether the sb->cleancache_poolid
	* is correct.
	*/
	int __cleancache_get_page(struct page *page)
	{
	int ret = -1;
	int pool_id;
	struct cleancache_filekey key = { .u.key = { 0 } };

	if (!cleancache_ops) {
	cleancache_failed_gets++;
	goto out;
	}

	VM_BUG_ON_PAGE(!PageLocked(page), 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.
	*
	* The function has two checks before any action is taken - whether
	* a backend is registered and whether the sb->cleancache_poolid
	* is correct.
	*/
	void __cleancache_put_page(struct page *page)
	{
	int pool_id;
	struct cleancache_filekey key = { .u.key = { 0 } };

	if (!cleancache_ops) {
	cleancache_puts++;
	return;
	}

	VM_BUG_ON_PAGE(!PageLocked(page), 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.
	*
	* The function has two checks before any action is taken - whether
	* a backend is registered and whether the sb->cleancache_poolid
	* is correct.
	*/
	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 (!cleancache_ops)
	return;

	if (pool_id >= 0) {
	VM_BUG_ON_PAGE(!PageLocked(page), 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.
	*
	* The function has two checks before any action is taken - whether
	* a backend is registered and whether the sb->cleancache_poolid
	* is correct.
	*/
	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 (!cleancache_ops)
	return;

	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 returned by a subsequent
	* cleancache_init_fs or cleancache_init_shared_fs.
	*/
	void __cleancache_invalidate_fs(struct super_block *sb)
	{
	int pool_id;

	pool_id = sb->cleancache_poolid;
	sb->cleancache_poolid = CLEANCACHE_NO_POOL;

	if (cleancache_ops && pool_id >= 0)
	cleancache_ops->invalidate_fs(pool_id);
	}
	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)