245 lines
6.9 KiB
C
245 lines
6.9 KiB
C
/*
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* Cleancache frontend
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*
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* This code provides the generic "frontend" layer to call a matching
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* "backend" driver implementation of cleancache. See
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* Documentation/vm/cleancache.txt for more information.
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*
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* Copyright (C) 2009-2010 Oracle Corp. All rights reserved.
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* Author: Dan Magenheimer
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*
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* This work is licensed under the terms of the GNU GPL, version 2.
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/exportfs.h>
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#include <linux/mm.h>
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#include <linux/cleancache.h>
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/*
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* This global enablement flag may be read thousands of times per second
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* by cleancache_get/put/flush even on systems where cleancache_ops
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* is not claimed (e.g. cleancache is config'ed on but remains
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* disabled), so is preferred to the slower alternative: a function
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* call that checks a non-global.
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*/
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int cleancache_enabled;
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EXPORT_SYMBOL(cleancache_enabled);
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/*
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* cleancache_ops is set by cleancache_ops_register to contain the pointers
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* to the cleancache "backend" implementation functions.
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*/
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static struct cleancache_ops cleancache_ops;
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/* useful stats available in /sys/kernel/mm/cleancache */
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static unsigned long cleancache_succ_gets;
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static unsigned long cleancache_failed_gets;
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static unsigned long cleancache_puts;
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static unsigned long cleancache_flushes;
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/*
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* register operations for cleancache, returning previous thus allowing
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* detection of multiple backends and possible nesting
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*/
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struct cleancache_ops cleancache_register_ops(struct cleancache_ops *ops)
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{
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struct cleancache_ops old = cleancache_ops;
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cleancache_ops = *ops;
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cleancache_enabled = 1;
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return old;
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}
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EXPORT_SYMBOL(cleancache_register_ops);
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/* Called by a cleancache-enabled filesystem at time of mount */
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void __cleancache_init_fs(struct super_block *sb)
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{
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sb->cleancache_poolid = (*cleancache_ops.init_fs)(PAGE_SIZE);
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}
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EXPORT_SYMBOL(__cleancache_init_fs);
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/* Called by a cleancache-enabled clustered filesystem at time of mount */
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void __cleancache_init_shared_fs(char *uuid, struct super_block *sb)
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{
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sb->cleancache_poolid =
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(*cleancache_ops.init_shared_fs)(uuid, PAGE_SIZE);
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}
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EXPORT_SYMBOL(__cleancache_init_shared_fs);
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/*
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* If the filesystem uses exportable filehandles, use the filehandle as
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* the key, else use the inode number.
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*/
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static int cleancache_get_key(struct inode *inode,
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struct cleancache_filekey *key)
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{
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int (*fhfn)(struct dentry *, __u32 *fh, int *, int);
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int len = 0, maxlen = CLEANCACHE_KEY_MAX;
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struct super_block *sb = inode->i_sb;
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key->u.ino = inode->i_ino;
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if (sb->s_export_op != NULL) {
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fhfn = sb->s_export_op->encode_fh;
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if (fhfn) {
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struct dentry d;
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d.d_inode = inode;
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len = (*fhfn)(&d, &key->u.fh[0], &maxlen, 0);
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if (len <= 0 || len == 255)
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return -1;
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if (maxlen > CLEANCACHE_KEY_MAX)
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return -1;
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}
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}
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return 0;
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}
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/*
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* "Get" data from cleancache associated with the poolid/inode/index
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* that were specified when the data was put to cleanache and, if
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* successful, use it to fill the specified page with data and return 0.
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* The pageframe is unchanged and returns -1 if the get fails.
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* Page must be locked by caller.
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*/
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int __cleancache_get_page(struct page *page)
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{
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int ret = -1;
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int pool_id;
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struct cleancache_filekey key = { .u.key = { 0 } };
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VM_BUG_ON(!PageLocked(page));
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pool_id = page->mapping->host->i_sb->cleancache_poolid;
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if (pool_id < 0)
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goto out;
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if (cleancache_get_key(page->mapping->host, &key) < 0)
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goto out;
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ret = (*cleancache_ops.get_page)(pool_id, key, page->index, page);
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if (ret == 0)
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cleancache_succ_gets++;
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else
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cleancache_failed_gets++;
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out:
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return ret;
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}
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EXPORT_SYMBOL(__cleancache_get_page);
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/*
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* "Put" data from a page to cleancache and associate it with the
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* (previously-obtained per-filesystem) poolid and the page's,
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* inode and page index. Page must be locked. Note that a put_page
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* always "succeeds", though a subsequent get_page may succeed or fail.
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*/
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void __cleancache_put_page(struct page *page)
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{
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int pool_id;
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struct cleancache_filekey key = { .u.key = { 0 } };
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VM_BUG_ON(!PageLocked(page));
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pool_id = page->mapping->host->i_sb->cleancache_poolid;
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if (pool_id >= 0 &&
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cleancache_get_key(page->mapping->host, &key) >= 0) {
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(*cleancache_ops.put_page)(pool_id, key, page->index, page);
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cleancache_puts++;
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}
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}
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EXPORT_SYMBOL(__cleancache_put_page);
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/*
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* Flush any data from cleancache associated with the poolid and the
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* page's inode and page index so that a subsequent "get" will fail.
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*/
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void __cleancache_flush_page(struct address_space *mapping, struct page *page)
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{
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/* careful... page->mapping is NULL sometimes when this is called */
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int pool_id = mapping->host->i_sb->cleancache_poolid;
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struct cleancache_filekey key = { .u.key = { 0 } };
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if (pool_id >= 0) {
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VM_BUG_ON(!PageLocked(page));
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if (cleancache_get_key(mapping->host, &key) >= 0) {
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(*cleancache_ops.flush_page)(pool_id, key, page->index);
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cleancache_flushes++;
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}
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}
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}
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EXPORT_SYMBOL(__cleancache_flush_page);
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/*
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* Flush all data from cleancache associated with the poolid and the
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* mappings's inode so that all subsequent gets to this poolid/inode
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* will fail.
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*/
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void __cleancache_flush_inode(struct address_space *mapping)
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{
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int pool_id = mapping->host->i_sb->cleancache_poolid;
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struct cleancache_filekey key = { .u.key = { 0 } };
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if (pool_id >= 0 && cleancache_get_key(mapping->host, &key) >= 0)
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(*cleancache_ops.flush_inode)(pool_id, key);
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}
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EXPORT_SYMBOL(__cleancache_flush_inode);
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/*
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* Called by any cleancache-enabled filesystem at time of unmount;
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* note that pool_id is surrendered and may be reutrned by a subsequent
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* cleancache_init_fs or cleancache_init_shared_fs
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*/
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void __cleancache_flush_fs(struct super_block *sb)
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{
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if (sb->cleancache_poolid >= 0) {
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int old_poolid = sb->cleancache_poolid;
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sb->cleancache_poolid = -1;
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(*cleancache_ops.flush_fs)(old_poolid);
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}
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}
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EXPORT_SYMBOL(__cleancache_flush_fs);
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#ifdef CONFIG_SYSFS
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/* see Documentation/ABI/xxx/sysfs-kernel-mm-cleancache */
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#define CLEANCACHE_SYSFS_RO(_name) \
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static ssize_t cleancache_##_name##_show(struct kobject *kobj, \
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struct kobj_attribute *attr, char *buf) \
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{ \
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return sprintf(buf, "%lu\n", cleancache_##_name); \
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} \
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static struct kobj_attribute cleancache_##_name##_attr = { \
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.attr = { .name = __stringify(_name), .mode = 0444 }, \
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.show = cleancache_##_name##_show, \
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}
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CLEANCACHE_SYSFS_RO(succ_gets);
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CLEANCACHE_SYSFS_RO(failed_gets);
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CLEANCACHE_SYSFS_RO(puts);
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CLEANCACHE_SYSFS_RO(flushes);
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static struct attribute *cleancache_attrs[] = {
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&cleancache_succ_gets_attr.attr,
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&cleancache_failed_gets_attr.attr,
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&cleancache_puts_attr.attr,
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&cleancache_flushes_attr.attr,
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NULL,
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};
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static struct attribute_group cleancache_attr_group = {
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.attrs = cleancache_attrs,
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.name = "cleancache",
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};
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#endif /* CONFIG_SYSFS */
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static int __init init_cleancache(void)
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{
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#ifdef CONFIG_SYSFS
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int err;
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err = sysfs_create_group(mm_kobj, &cleancache_attr_group);
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#endif /* CONFIG_SYSFS */
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return 0;
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}
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module_init(init_cleancache)
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