+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * 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
- */
-
-#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);
-
- debugfs_create_u64("succ_gets", 0444, root, &cleancache_succ_gets);
- debugfs_create_u64("failed_gets", 0444, root, &cleancache_failed_gets);
- debugfs_create_u64("puts", 0444, root, &cleancache_puts);
- debugfs_create_u64("invalidates", 0444, root, &cleancache_invalidates);
-#endif
- return 0;
-}
-module_init(init_cleancache)
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