/* * 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 #include #include #include #include #include /* * 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 <= 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); /* * 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)