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315 lines
9.8 KiB
315 lines
9.8 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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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.rst 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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#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/debugfs.h> |
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#include <linux/cleancache.h> |
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/* |
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* cleancache_ops is set by cleancache_register_ops to contain the pointers |
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* to the cleancache "backend" implementation functions. |
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*/ |
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static const struct cleancache_ops *cleancache_ops __read_mostly; |
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|
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/* |
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* Counters available via /sys/kernel/debug/cleancache (if debugfs is |
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* properly configured. These are for information only so are not protected |
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* against increment races. |
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*/ |
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static u64 cleancache_succ_gets; |
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static u64 cleancache_failed_gets; |
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static u64 cleancache_puts; |
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static u64 cleancache_invalidates; |
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static void cleancache_register_ops_sb(struct super_block *sb, void *unused) |
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{ |
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switch (sb->cleancache_poolid) { |
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case CLEANCACHE_NO_BACKEND: |
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__cleancache_init_fs(sb); |
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break; |
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case CLEANCACHE_NO_BACKEND_SHARED: |
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__cleancache_init_shared_fs(sb); |
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break; |
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} |
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} |
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/* |
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* Register operations for cleancache. Returns 0 on success. |
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*/ |
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int cleancache_register_ops(const struct cleancache_ops *ops) |
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{ |
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if (cmpxchg(&cleancache_ops, NULL, ops)) |
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return -EBUSY; |
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/* |
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* A cleancache backend can be built as a module and hence loaded after |
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* a cleancache enabled filesystem has called cleancache_init_fs. To |
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* handle such a scenario, here we call ->init_fs or ->init_shared_fs |
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* for each active super block. To differentiate between local and |
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* shared filesystems, we temporarily initialize sb->cleancache_poolid |
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* to CLEANCACHE_NO_BACKEND or CLEANCACHE_NO_BACKEND_SHARED |
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* respectively in case there is no backend registered at the time |
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* cleancache_init_fs or cleancache_init_shared_fs is called. |
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* |
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* Since filesystems can be mounted concurrently with cleancache |
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* backend registration, we have to be careful to guarantee that all |
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* cleancache enabled filesystems that has been mounted by the time |
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* cleancache_register_ops is called has got and all mounted later will |
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* get cleancache_poolid. This is assured by the following statements |
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* tied together: |
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* |
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* a) iterate_supers skips only those super blocks that has started |
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* ->kill_sb |
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* |
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* b) if iterate_supers encounters a super block that has not finished |
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* ->mount yet, it waits until it is finished |
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* |
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* c) cleancache_init_fs is called from ->mount and |
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* cleancache_invalidate_fs is called from ->kill_sb |
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* |
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* d) we call iterate_supers after cleancache_ops has been set |
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* |
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* From a) it follows that if iterate_supers skips a super block, then |
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* either the super block is already dead, in which case we do not need |
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* to bother initializing cleancache for it, or it was mounted after we |
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* initiated iterate_supers. In the latter case, it must have seen |
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* cleancache_ops set according to d) and initialized cleancache from |
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* ->mount by itself according to c). This proves that we call |
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* ->init_fs at least once for each active super block. |
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* |
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* From b) and c) it follows that if iterate_supers encounters a super |
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* block that has already started ->init_fs, it will wait until ->mount |
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* and hence ->init_fs has finished, then check cleancache_poolid, see |
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* that it has already been set and therefore do nothing. This proves |
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* that we call ->init_fs no more than once for each super block. |
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* |
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* Combined together, the last two paragraphs prove the function |
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* correctness. |
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* |
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* Note that various cleancache callbacks may proceed before this |
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* function is called or even concurrently with it, but since |
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* CLEANCACHE_NO_BACKEND is negative, they will all result in a noop |
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* until the corresponding ->init_fs has been actually called and |
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* cleancache_ops has been set. |
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*/ |
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iterate_supers(cleancache_register_ops_sb, NULL); |
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return 0; |
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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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int pool_id = CLEANCACHE_NO_BACKEND; |
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if (cleancache_ops) { |
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pool_id = cleancache_ops->init_fs(PAGE_SIZE); |
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if (pool_id < 0) |
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pool_id = CLEANCACHE_NO_POOL; |
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} |
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sb->cleancache_poolid = pool_id; |
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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(struct super_block *sb) |
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{ |
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int pool_id = CLEANCACHE_NO_BACKEND_SHARED; |
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if (cleancache_ops) { |
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pool_id = cleancache_ops->init_shared_fs(&sb->s_uuid, PAGE_SIZE); |
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if (pool_id < 0) |
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pool_id = CLEANCACHE_NO_POOL; |
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} |
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sb->cleancache_poolid = pool_id; |
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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 inode *, __u32 *fh, int *, struct inode *); |
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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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len = (*fhfn)(inode, &key->u.fh[0], &maxlen, NULL); |
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if (len <= FILEID_ROOT || len == FILEID_INVALID) |
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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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* The function has two checks before any action is taken - whether |
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* a backend is registered and whether the sb->cleancache_poolid |
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* is correct. |
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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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if (!cleancache_ops) { |
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cleancache_failed_gets++; |
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goto out; |
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} |
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VM_BUG_ON_PAGE(!PageLocked(page), 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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* The function has two checks before any action is taken - whether |
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* a backend is registered and whether the sb->cleancache_poolid |
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* is correct. |
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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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if (!cleancache_ops) { |
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cleancache_puts++; |
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return; |
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} |
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VM_BUG_ON_PAGE(!PageLocked(page), 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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* Invalidate 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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* The function has two checks before any action is taken - whether |
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* a backend is registered and whether the sb->cleancache_poolid |
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* is correct. |
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*/ |
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void __cleancache_invalidate_page(struct address_space *mapping, |
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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 (!cleancache_ops) |
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return; |
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if (pool_id >= 0) { |
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VM_BUG_ON_PAGE(!PageLocked(page), page); |
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if (cleancache_get_key(mapping->host, &key) >= 0) { |
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cleancache_ops->invalidate_page(pool_id, |
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key, page->index); |
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cleancache_invalidates++; |
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} |
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} |
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} |
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EXPORT_SYMBOL(__cleancache_invalidate_page); |
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/* |
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* Invalidate 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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* The function has two checks before any action is taken - whether |
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* a backend is registered and whether the sb->cleancache_poolid |
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* is correct. |
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*/ |
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void __cleancache_invalidate_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 (!cleancache_ops) |
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return; |
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if (pool_id >= 0 && cleancache_get_key(mapping->host, &key) >= 0) |
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cleancache_ops->invalidate_inode(pool_id, key); |
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} |
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EXPORT_SYMBOL(__cleancache_invalidate_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 returned 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_invalidate_fs(struct super_block *sb) |
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{ |
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int pool_id; |
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pool_id = sb->cleancache_poolid; |
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sb->cleancache_poolid = CLEANCACHE_NO_POOL; |
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if (cleancache_ops && pool_id >= 0) |
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cleancache_ops->invalidate_fs(pool_id); |
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} |
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EXPORT_SYMBOL(__cleancache_invalidate_fs); |
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static int __init init_cleancache(void) |
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{ |
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#ifdef CONFIG_DEBUG_FS |
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struct dentry *root = debugfs_create_dir("cleancache", NULL); |
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debugfs_create_u64("succ_gets", 0444, root, &cleancache_succ_gets); |
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debugfs_create_u64("failed_gets", 0444, root, &cleancache_failed_gets); |
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debugfs_create_u64("puts", 0444, root, &cleancache_puts); |
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debugfs_create_u64("invalidates", 0444, root, &cleancache_invalidates); |
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#endif |
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return 0; |
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} |
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module_init(init_cleancache)
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