+++ /dev/null
-.. _cleancache:
-
-==========
-Cleancache
-==========
-
-Motivation
-==========
-
-Cleancache is a new optional feature provided by the VFS layer that
-potentially dramatically increases page cache effectiveness for
-many workloads in many environments at a negligible cost.
-
-Cleancache can be thought of as a page-granularity victim cache for clean
-pages that the kernel's pageframe replacement algorithm (PFRA) would like
-to keep around, but can't since there isn't enough memory. So when the
-PFRA "evicts" a page, it first attempts to use cleancache code to
-put the data contained in that page into "transcendent memory", memory
-that is not directly accessible or addressable by the kernel and is
-of unknown and possibly time-varying size.
-
-Later, when a cleancache-enabled filesystem wishes to access a page
-in a file on disk, it first checks cleancache to see if it already
-contains it; if it does, the page of data is copied into the kernel
-and a disk access is avoided.
-
-Transcendent memory "drivers" for cleancache are currently implemented
-in Xen (using hypervisor memory) and zcache (using in-kernel compressed
-memory) and other implementations are in development.
-
-:ref:`FAQs <faq>` are included below.
-
-Implementation Overview
-=======================
-
-A cleancache "backend" that provides transcendent memory registers itself
-to the kernel's cleancache "frontend" by calling cleancache_register_ops,
-passing a pointer to a cleancache_ops structure with funcs set appropriately.
-The functions provided must conform to certain semantics as follows:
-
-Most important, cleancache is "ephemeral". Pages which are copied into
-cleancache have an indefinite lifetime which is completely unknowable
-by the kernel and so may or may not still be in cleancache at any later time.
-Thus, as its name implies, cleancache is not suitable for dirty pages.
-Cleancache has complete discretion over what pages to preserve and what
-pages to discard and when.
-
-Mounting a cleancache-enabled filesystem should call "init_fs" to obtain a
-pool id which, if positive, must be saved in the filesystem's superblock;
-a negative return value indicates failure. A "put_page" will copy a
-(presumably about-to-be-evicted) page into cleancache and associate it with
-the pool id, a file key, and a page index into the file. (The combination
-of a pool id, a file key, and an index is sometimes called a "handle".)
-A "get_page" will copy the page, if found, from cleancache into kernel memory.
-An "invalidate_page" will ensure the page no longer is present in cleancache;
-an "invalidate_inode" will invalidate all pages associated with the specified
-file; and, when a filesystem is unmounted, an "invalidate_fs" will invalidate
-all pages in all files specified by the given pool id and also surrender
-the pool id.
-
-An "init_shared_fs", like init_fs, obtains a pool id but tells cleancache
-to treat the pool as shared using a 128-bit UUID as a key. On systems
-that may run multiple kernels (such as hard partitioned or virtualized
-systems) that may share a clustered filesystem, and where cleancache
-may be shared among those kernels, calls to init_shared_fs that specify the
-same UUID will receive the same pool id, thus allowing the pages to
-be shared. Note that any security requirements must be imposed outside
-of the kernel (e.g. by "tools" that control cleancache). Or a
-cleancache implementation can simply disable shared_init by always
-returning a negative value.
-
-If a get_page is successful on a non-shared pool, the page is invalidated
-(thus making cleancache an "exclusive" cache). On a shared pool, the page
-is NOT invalidated on a successful get_page so that it remains accessible to
-other sharers. The kernel is responsible for ensuring coherency between
-cleancache (shared or not), the page cache, and the filesystem, using
-cleancache invalidate operations as required.
-
-Note that cleancache must enforce put-put-get coherency and get-get
-coherency. For the former, if two puts are made to the same handle but
-with different data, say AAA by the first put and BBB by the second, a
-subsequent get can never return the stale data (AAA). For get-get coherency,
-if a get for a given handle fails, subsequent gets for that handle will
-never succeed unless preceded by a successful put with that handle.
-
-Last, cleancache provides no SMP serialization guarantees; if two
-different Linux threads are simultaneously putting and invalidating a page
-with the same handle, the results are indeterminate. Callers must
-lock the page to ensure serial behavior.
-
-Cleancache Performance Metrics
-==============================
-
-If properly configured, monitoring of cleancache is done via debugfs in
-the `/sys/kernel/debug/cleancache` directory. The effectiveness of cleancache
-can be measured (across all filesystems) with:
-
-``succ_gets``
- number of gets that were successful
-
-``failed_gets``
- number of gets that failed
-
-``puts``
- number of puts attempted (all "succeed")
-
-``invalidates``
- number of invalidates attempted
-
-A backend implementation may provide additional metrics.
-
-.. _faq:
-
-FAQ
-===
-
-* Where's the value? (Andrew Morton)
-
-Cleancache provides a significant performance benefit to many workloads
-in many environments with negligible overhead by improving the
-effectiveness of the pagecache. Clean pagecache pages are
-saved in transcendent memory (RAM that is otherwise not directly
-addressable to the kernel); fetching those pages later avoids "refaults"
-and thus disk reads.
-
-Cleancache (and its sister code "frontswap") provide interfaces for
-this transcendent memory (aka "tmem"), which conceptually lies between
-fast kernel-directly-addressable RAM and slower DMA/asynchronous devices.
-Disallowing direct kernel or userland reads/writes to tmem
-is ideal when data is transformed to a different form and size (such
-as with compression) or secretly moved (as might be useful for write-
-balancing for some RAM-like devices). Evicted page-cache pages (and
-swap pages) are a great use for this kind of slower-than-RAM-but-much-
-faster-than-disk transcendent memory, and the cleancache (and frontswap)
-"page-object-oriented" specification provides a nice way to read and
-write -- and indirectly "name" -- the pages.
-
-In the virtual case, the whole point of virtualization is to statistically
-multiplex physical resources across the varying demands of multiple
-virtual machines. This is really hard to do with RAM and efforts to
-do it well with no kernel change have essentially failed (except in some
-well-publicized special-case workloads). Cleancache -- and frontswap --
-with a fairly small impact on the kernel, provide a huge amount
-of flexibility for more dynamic, flexible RAM multiplexing.
-Specifically, the Xen Transcendent Memory backend allows otherwise
-"fallow" hypervisor-owned RAM to not only be "time-shared" between multiple
-virtual machines, but the pages can be compressed and deduplicated to
-optimize RAM utilization. And when guest OS's are induced to surrender
-underutilized RAM (e.g. with "self-ballooning"), page cache pages
-are the first to go, and cleancache allows those pages to be
-saved and reclaimed if overall host system memory conditions allow.
-
-And the identical interface used for cleancache can be used in
-physical systems as well. The zcache driver acts as a memory-hungry
-device that stores pages of data in a compressed state. And
-the proposed "RAMster" driver shares RAM across multiple physical
-systems.
-
-* Why does cleancache have its sticky fingers so deep inside the
- filesystems and VFS? (Andrew Morton and Christoph Hellwig)
-
-The core hooks for cleancache in VFS are in most cases a single line
-and the minimum set are placed precisely where needed to maintain
-coherency (via cleancache_invalidate operations) between cleancache,
-the page cache, and disk. All hooks compile into nothingness if
-cleancache is config'ed off and turn into a function-pointer-
-compare-to-NULL if config'ed on but no backend claims the ops
-functions, or to a compare-struct-element-to-negative if a
-backend claims the ops functions but a filesystem doesn't enable
-cleancache.
-
-Some filesystems are built entirely on top of VFS and the hooks
-in VFS are sufficient, so don't require an "init_fs" hook; the
-initial implementation of cleancache didn't provide this hook.
-But for some filesystems (such as btrfs), the VFS hooks are
-incomplete and one or more hooks in fs-specific code are required.
-And for some other filesystems, such as tmpfs, cleancache may
-be counterproductive. So it seemed prudent to require a filesystem
-to "opt in" to use cleancache, which requires adding a hook in
-each filesystem. Not all filesystems are supported by cleancache
-only because they haven't been tested. The existing set should
-be sufficient to validate the concept, the opt-in approach means
-that untested filesystems are not affected, and the hooks in the
-existing filesystems should make it very easy to add more
-filesystems in the future.
-
-The total impact of the hooks to existing fs and mm files is only
-about 40 lines added (not counting comments and blank lines).
-
-* Why not make cleancache asynchronous and batched so it can more
- easily interface with real devices with DMA instead of copying each
- individual page? (Minchan Kim)
-
-The one-page-at-a-time copy semantics simplifies the implementation
-on both the frontend and backend and also allows the backend to
-do fancy things on-the-fly like page compression and
-page deduplication. And since the data is "gone" (copied into/out
-of the pageframe) before the cleancache get/put call returns,
-a great deal of race conditions and potential coherency issues
-are avoided. While the interface seems odd for a "real device"
-or for real kernel-addressable RAM, it makes perfect sense for
-transcendent memory.
-
-* Why is non-shared cleancache "exclusive"? And where is the
- page "invalidated" after a "get"? (Minchan Kim)
-
-The main reason is to free up space in transcendent memory and
-to avoid unnecessary cleancache_invalidate calls. If you want inclusive,
-the page can be "put" immediately following the "get". If
-put-after-get for inclusive becomes common, the interface could
-be easily extended to add a "get_no_invalidate" call.
-
-The invalidate is done by the cleancache backend implementation.
-
-* What's the performance impact?
-
-Performance analysis has been presented at OLS'09 and LCA'10.
-Briefly, performance gains can be significant on most workloads,
-especially when memory pressure is high (e.g. when RAM is
-overcommitted in a virtual workload); and because the hooks are
-invoked primarily in place of or in addition to a disk read/write,
-overhead is negligible even in worst case workloads. Basically
-cleancache replaces I/O with memory-copy-CPU-overhead; on older
-single-core systems with slow memory-copy speeds, cleancache
-has little value, but in newer multicore machines, especially
-consolidated/virtualized machines, it has great value.
-
-* How do I add cleancache support for filesystem X? (Boaz Harrash)
-
-Filesystems that are well-behaved and conform to certain
-restrictions can utilize cleancache simply by making a call to
-cleancache_init_fs at mount time. Unusual, misbehaving, or
-poorly layered filesystems must either add additional hooks
-and/or undergo extensive additional testing... or should just
-not enable the optional cleancache.
-
-Some points for a filesystem to consider:
-
- - The FS should be block-device-based (e.g. a ram-based FS such
- as tmpfs should not enable cleancache)
- - To ensure coherency/correctness, the FS must ensure that all
- file removal or truncation operations either go through VFS or
- add hooks to do the equivalent cleancache "invalidate" operations
- - To ensure coherency/correctness, either inode numbers must
- be unique across the lifetime of the on-disk file OR the
- FS must provide an "encode_fh" function.
- - The FS must call the VFS superblock alloc and deactivate routines
- or add hooks to do the equivalent cleancache calls done there.
- - To maximize performance, all pages fetched from the FS should
- go through the do_mpag_readpage routine or the FS should add
- hooks to do the equivalent (cf. btrfs)
- - Currently, the FS blocksize must be the same as PAGESIZE. This
- is not an architectural restriction, but no backends currently
- support anything different.
- - A clustered FS should invoke the "shared_init_fs" cleancache
- hook to get best performance for some backends.
-
-* Why not use the KVA of the inode as the key? (Christoph Hellwig)
-
-If cleancache would use the inode virtual address instead of
-inode/filehandle, the pool id could be eliminated. But, this
-won't work because cleancache retains pagecache data pages
-persistently even when the inode has been pruned from the
-inode unused list, and only invalidates the data page if the file
-gets removed/truncated. So if cleancache used the inode kva,
-there would be potential coherency issues if/when the inode
-kva is reused for a different file. Alternately, if cleancache
-invalidated the pages when the inode kva was freed, much of the value
-of cleancache would be lost because the cache of pages in cleanache
-is potentially much larger than the kernel pagecache and is most
-useful if the pages survive inode cache removal.
-
-* Why is a global variable required?
-
-The cleancache_enabled flag is checked in all of the frequently-used
-cleancache hooks. The alternative is a function call to check a static
-variable. Since cleancache is enabled dynamically at runtime, systems
-that don't enable cleancache would suffer thousands (possibly
-tens-of-thousands) of unnecessary function calls per second. So the
-global variable allows cleancache to be enabled by default at compile
-time, but have insignificant performance impact when cleancache remains
-disabled at runtime.
-
-* Does cleanache work with KVM?
-
-The memory model of KVM is sufficiently different that a cleancache
-backend may have less value for KVM. This remains to be tested,
-especially in an overcommitted system.
-
-* Does cleancache work in userspace? It sounds useful for
- memory hungry caches like web browsers. (Jamie Lokier)
-
-No plans yet, though we agree it sounds useful, at least for
-apps that bypass the page cache (e.g. O_DIRECT).
-
-Last updated: Dan Magenheimer, April 13 2011
In some environments, dramatic performance savings may be obtained because
swapped pages are saved in RAM (or a RAM-like device) instead of a swap disk.
-(Note, frontswap -- and :ref:`cleancache` (merged at 3.0) -- are the "frontends"
-and the only necessary changes to the core kernel for transcendent memory;
-all other supporting code -- the "backends" -- is implemented as drivers.
-See the LWN.net article `Transcendent memory in a nutshell`_
-for a detailed overview of frontswap and related kernel parts)
-
.. _Transcendent memory in a nutshell: https://lwn.net/Articles/454795/
Frontswap is so named because it can be thought of as the opposite of
and size (such as with compression) or secretly moved (as might be
useful for write-balancing for some RAM-like devices). Swap pages (and
evicted page-cache pages) are a great use for this kind of slower-than-RAM-
-but-much-faster-than-disk "pseudo-RAM device" and the frontswap (and
-cleancache) interface to transcendent memory provides a nice way to read
-and write -- and indirectly "name" -- the pages.
+but-much-faster-than-disk "pseudo-RAM device".
-Frontswap -- and cleancache -- with a fairly small impact on the kernel,
+Frontswap with a fairly small impact on the kernel,
provides a huge amount of flexibility for more dynamic, flexible RAM
utilization in various system configurations:
active_mm
arch_pgtable_helpers
balance
- cleancache
damon/index
free_page_reporting
frontswap
F: include/linux/cfi.h
F: kernel/cfi.c
-CLEANCACHE API
-M: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
-L: linux-kernel@vger.kernel.org
-S: Maintained
-F: include/linux/cleancache.h
-F: mm/cleancache.c
-
CLK API
M: Russell King <linux@armlinux.org.uk>
L: linux-clk@vger.kernel.org
CONFIG_PREEMPT_VOLUNTARY=y
CONFIG_AEABI=y
CONFIG_KSM=y
-CONFIG_CLEANCACHE=y
CONFIG_CMA=y
CONFIG_SECCOMP=y
CONFIG_KEXEC=y
CONFIG_SMP=y
CONFIG_PREEMPT=y
CONFIG_HIGHMEM=y
-CONFIG_CLEANCACHE=y
CONFIG_ARM_APPENDED_DTB=y
CONFIG_ARM_ATAG_DTB_COMPAT=y
CONFIG_CPU_IDLE=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_BINFMT_AOUT=m
CONFIG_BINFMT_MISC=m
# CONFIG_COMPACTION is not set
-CONFIG_CLEANCACHE=y
CONFIG_ZPOOL=m
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_MEMORY_HOTREMOVE=y
CONFIG_KSM=y
CONFIG_TRANSPARENT_HUGEPAGE=y
-CONFIG_CLEANCACHE=y
CONFIG_FRONTSWAP=y
CONFIG_CMA_DEBUG=y
CONFIG_CMA_DEBUGFS=y
CONFIG_MEMORY_HOTREMOVE=y
CONFIG_KSM=y
CONFIG_TRANSPARENT_HUGEPAGE=y
-CONFIG_CLEANCACHE=y
CONFIG_FRONTSWAP=y
CONFIG_CMA_SYSFS=y
CONFIG_CMA_AREAS=7
#include <linux/pseudo_fs.h>
#include <linux/uio.h>
#include <linux/namei.h>
-#include <linux/cleancache.h>
#include <linux/part_stat.h>
#include <linux/uaccess.h>
#include "../fs/internal.h"
lru_add_drain_all(); /* make sure all lru add caches are flushed */
invalidate_mapping_pages(mapping, 0, -1);
}
- /* 99% of the time, we don't need to flush the cleancache on the bdev.
- * But, for the strange corners, lets be cautious
- */
- cleancache_invalidate_inode(mapping);
}
EXPORT_SYMBOL(invalidate_bdev);
#include <linux/writeback.h>
#include <linux/pagevec.h>
#include <linux/prefetch.h>
-#include <linux/cleancache.h>
#include <linux/fsverity.h>
#include "misc.h"
#include "extent_io.h"
goto out;
}
- if (!PageUptodate(page)) {
- if (cleancache_get_page(page) == 0) {
- BUG_ON(blocksize != PAGE_SIZE);
- unlock_extent(tree, start, end);
- unlock_page(page);
- goto out;
- }
- }
-
if (page->index == last_byte >> PAGE_SHIFT) {
size_t zero_offset = offset_in_page(last_byte);
#include <linux/miscdevice.h>
#include <linux/magic.h>
#include <linux/slab.h>
-#include <linux/cleancache.h>
#include <linux/ratelimit.h>
#include <linux/crc32c.h>
#include <linux/btrfs.h>
goto fail_close;
}
- cleancache_init_fs(sb);
sb->s_flags |= SB_ACTIVE;
return 0;
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
-#include <linux/cleancache.h>
#include "ext4.h"
} else if (fully_mapped) {
SetPageMappedToDisk(page);
}
- if (fully_mapped && blocks_per_page == 1 &&
- !PageUptodate(page) && cleancache_get_page(page) == 0) {
- SetPageUptodate(page);
- goto confused;
- }
/*
* This page will go to BIO. Do we need to send this
#include <linux/log2.h>
#include <linux/crc16.h>
#include <linux/dax.h>
-#include <linux/cleancache.h>
#include <linux/uaccess.h>
#include <linux/iversion.h>
#include <linux/unicode.h>
EXT4_BLOCKS_PER_GROUP(sb),
EXT4_INODES_PER_GROUP(sb),
sbi->s_mount_opt, sbi->s_mount_opt2);
-
- cleancache_init_fs(sb);
return err;
}
#include <linux/swap.h>
#include <linux/prefetch.h>
#include <linux/uio.h>
-#include <linux/cleancache.h>
#include <linux/sched/signal.h>
#include <linux/fiemap.h>
#include <linux/iomap.h>
block_nr = map->m_pblk + block_in_file - map->m_lblk;
SetPageMappedToDisk(page);
- if (!PageUptodate(page) && (!PageSwapCache(page) &&
- !cleancache_get_page(page))) {
- SetPageUptodate(page);
- goto confused;
- }
-
if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode), block_nr,
DATA_GENERIC_ENHANCE_READ)) {
ret = -EFSCORRUPTED;
ClearPageError(page);
*last_block_in_bio = block_nr;
goto out;
-confused:
- if (bio) {
- __submit_bio(F2FS_I_SB(inode), bio, DATA);
- bio = NULL;
- }
- unlock_page(page);
out:
*bio_ret = bio;
return ret;
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
-#include <linux/cleancache.h>
#include "internal.h"
/*
SetPageMappedToDisk(page);
}
- if (fully_mapped && blocks_per_page == 1 && !PageUptodate(page) &&
- cleancache_get_page(page) == 0) {
- SetPageUptodate(page);
- goto confused;
- }
-
/*
* This page will go to BIO. Do we need to send this BIO off first?
*/
#include <linux/blkdev.h>
#include <linux/buffer_head.h>
-#include <linux/cleancache.h>
#include <linux/fs.h>
#include <linux/highmem.h>
#include <linux/kernel.h>
#include <linux/mount.h>
#include <linux/seq_file.h>
#include <linux/quotaops.h>
-#include <linux/cleancache.h>
#include <linux/signal.h>
#define CREATE_TRACE_POINTS
mlog_errno(status);
goto bail;
}
- cleancache_init_shared_fs(sb);
osb->ocfs2_wq = alloc_ordered_workqueue("ocfs2_wq", WQ_MEM_RECLAIM);
if (!osb->ocfs2_wq) {
#include <linux/mutex.h>
#include <linux/backing-dev.h>
#include <linux/rculist_bl.h>
-#include <linux/cleancache.h>
#include <linux/fscrypt.h>
#include <linux/fsnotify.h>
#include <linux/lockdep.h>
s->s_time_gran = 1000000000;
s->s_time_min = TIME64_MIN;
s->s_time_max = TIME64_MAX;
- s->cleancache_poolid = CLEANCACHE_NO_POOL;
s->s_shrink.seeks = DEFAULT_SEEKS;
s->s_shrink.scan_objects = super_cache_scan;
{
struct file_system_type *fs = s->s_type;
if (atomic_dec_and_test(&s->s_active)) {
- cleancache_invalidate_fs(s);
unregister_shrinker(&s->s_shrink);
fs->kill_sb(s);
+++ /dev/null
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _LINUX_CLEANCACHE_H
-#define _LINUX_CLEANCACHE_H
-
-#include <linux/fs.h>
-#include <linux/exportfs.h>
-#include <linux/mm.h>
-
-#define CLEANCACHE_NO_POOL -1
-#define CLEANCACHE_NO_BACKEND -2
-#define CLEANCACHE_NO_BACKEND_SHARED -3
-
-#define CLEANCACHE_KEY_MAX 6
-
-/*
- * cleancache requires every file with a page in cleancache to have a
- * unique key unless/until the file is removed/truncated. For some
- * filesystems, the inode number is unique, but for "modern" filesystems
- * an exportable filehandle is required (see exportfs.h)
- */
-struct cleancache_filekey {
- union {
- ino_t ino;
- __u32 fh[CLEANCACHE_KEY_MAX];
- u32 key[CLEANCACHE_KEY_MAX];
- } u;
-};
-
-struct cleancache_ops {
- int (*init_fs)(size_t);
- int (*init_shared_fs)(uuid_t *uuid, size_t);
- int (*get_page)(int, struct cleancache_filekey,
- pgoff_t, struct page *);
- void (*put_page)(int, struct cleancache_filekey,
- pgoff_t, struct page *);
- void (*invalidate_page)(int, struct cleancache_filekey, pgoff_t);
- void (*invalidate_inode)(int, struct cleancache_filekey);
- void (*invalidate_fs)(int);
-};
-
-extern int cleancache_register_ops(const struct cleancache_ops *ops);
-extern void __cleancache_init_fs(struct super_block *);
-extern void __cleancache_init_shared_fs(struct super_block *);
-extern int __cleancache_get_page(struct page *);
-extern void __cleancache_put_page(struct page *);
-extern void __cleancache_invalidate_page(struct address_space *, struct page *);
-extern void __cleancache_invalidate_inode(struct address_space *);
-extern void __cleancache_invalidate_fs(struct super_block *);
-
-#ifdef CONFIG_CLEANCACHE
-#define cleancache_enabled (1)
-static inline bool cleancache_fs_enabled_mapping(struct address_space *mapping)
-{
- return mapping->host->i_sb->cleancache_poolid >= 0;
-}
-static inline bool cleancache_fs_enabled(struct page *page)
-{
- return cleancache_fs_enabled_mapping(page->mapping);
-}
-#else
-#define cleancache_enabled (0)
-#define cleancache_fs_enabled(_page) (0)
-#define cleancache_fs_enabled_mapping(_page) (0)
-#endif
-
-/*
- * The shim layer provided by these inline functions allows the compiler
- * to reduce all cleancache hooks to nothingness if CONFIG_CLEANCACHE
- * is disabled, to a single global variable check if CONFIG_CLEANCACHE
- * is enabled but no cleancache "backend" has dynamically enabled it,
- * and, for the most frequent cleancache ops, to a single global variable
- * check plus a superblock element comparison if CONFIG_CLEANCACHE is enabled
- * and a cleancache backend has dynamically enabled cleancache, but the
- * filesystem referenced by that cleancache op has not enabled cleancache.
- * As a result, CONFIG_CLEANCACHE can be enabled by default with essentially
- * no measurable performance impact.
- */
-
-static inline void cleancache_init_fs(struct super_block *sb)
-{
- if (cleancache_enabled)
- __cleancache_init_fs(sb);
-}
-
-static inline void cleancache_init_shared_fs(struct super_block *sb)
-{
- if (cleancache_enabled)
- __cleancache_init_shared_fs(sb);
-}
-
-static inline int cleancache_get_page(struct page *page)
-{
- if (cleancache_enabled && cleancache_fs_enabled(page))
- return __cleancache_get_page(page);
- return -1;
-}
-
-static inline void cleancache_put_page(struct page *page)
-{
- if (cleancache_enabled && cleancache_fs_enabled(page))
- __cleancache_put_page(page);
-}
-
-static inline void cleancache_invalidate_page(struct address_space *mapping,
- struct page *page)
-{
- /* careful... page->mapping is NULL sometimes when this is called */
- if (cleancache_enabled && cleancache_fs_enabled_mapping(mapping))
- __cleancache_invalidate_page(mapping, page);
-}
-
-static inline void cleancache_invalidate_inode(struct address_space *mapping)
-{
- if (cleancache_enabled && cleancache_fs_enabled_mapping(mapping))
- __cleancache_invalidate_inode(mapping);
-}
-
-static inline void cleancache_invalidate_fs(struct super_block *sb)
-{
- if (cleancache_enabled)
- __cleancache_invalidate_fs(sb);
-}
-
-#endif /* _LINUX_CLEANCACHE_H */
const struct dentry_operations *s_d_op; /* default d_op for dentries */
- /*
- * Saved pool identifier for cleancache (-1 means none)
- */
- int cleancache_poolid;
-
struct shrinker s_shrink; /* per-sb shrinker handle */
/* Number of inodes with nlink == 0 but still referenced */
config HAVE_SETUP_PER_CPU_AREA
bool
-config CLEANCACHE
- bool "Enable cleancache driver to cache clean pages if tmem is present"
- help
- Cleancache can be thought of as a page-granularity victim cache
- for clean pages that the kernel's pageframe replacement algorithm
- (PFRA) would like to keep around, but can't since there isn't enough
- memory. So when the PFRA "evicts" a page, it first attempts to use
- cleancache code to put the data contained in that page into
- "transcendent memory", memory that is not directly accessible or
- addressable by the kernel and is of unknown and possibly
- time-varying size. And when a cleancache-enabled
- filesystem wishes to access a page in a file on disk, it first
- checks cleancache to see if it already contains it; if it does,
- the page is copied into the kernel and a disk access is avoided.
- When a transcendent memory driver is available (such as zcache or
- Xen transcendent memory), a significant I/O reduction
- may be achieved. When none is available, all cleancache calls
- are reduced to a single pointer-compare-against-NULL resulting
- in a negligible performance hit.
-
- If unsure, say Y to enable cleancache
-
config FRONTSWAP
bool "Enable frontswap to cache swap pages if tmem is present"
depends on SWAP
obj-$(CONFIG_DEBUG_RODATA_TEST) += rodata_test.o
obj-$(CONFIG_DEBUG_VM_PGTABLE) += debug_vm_pgtable.o
obj-$(CONFIG_PAGE_OWNER) += page_owner.o
-obj-$(CONFIG_CLEANCACHE) += cleancache.o
obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o
obj-$(CONFIG_ZPOOL) += zpool.o
obj-$(CONFIG_ZBUD) += zbud.o
+++ /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)
#include <linux/cpuset.h>
#include <linux/hugetlb.h>
#include <linux/memcontrol.h>
-#include <linux/cleancache.h>
#include <linux/shmem_fs.h>
#include <linux/rmap.h>
#include <linux/delayacct.h>
{
long nr;
- /*
- * if we're uptodate, flush out into the cleancache, otherwise
- * invalidate any existing cleancache entries. We can't leave
- * stale data around in the cleancache once our page is gone
- */
- if (folio_test_uptodate(folio) && folio_test_mappedtodisk(folio))
- cleancache_put_page(&folio->page);
- else
- cleancache_invalidate_page(mapping, &folio->page);
-
VM_BUG_ON_FOLIO(folio_mapped(folio), folio);
if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(folio_mapped(folio))) {
int mapcount;
#include <linux/buffer_head.h> /* grr. try_to_release_page,
do_invalidatepage */
#include <linux/shmem_fs.h>
-#include <linux/cleancache.h>
#include <linux/rmap.h>
#include "internal.h"
*/
folio_zero_range(folio, offset, length);
- cleancache_invalidate_page(folio->mapping, &folio->page);
if (folio_has_private(folio))
do_invalidatepage(&folio->page, offset, length);
if (!folio_test_large(folio))
bool same_folio;
if (mapping_empty(mapping))
- goto out;
+ return;
/*
* 'start' and 'end' always covers the range of pages to be fully
folio_batch_release(&fbatch);
index++;
}
-
-out:
- cleancache_invalidate_inode(mapping);
}
EXPORT_SYMBOL(truncate_inode_pages_range);
xa_unlock_irq(&mapping->i_pages);
}
- /*
- * Cleancache needs notification even if there are no pages or shadow
- * entries.
- */
truncate_inode_pages(mapping, 0);
}
EXPORT_SYMBOL(truncate_inode_pages_final);
int did_range_unmap = 0;
if (mapping_empty(mapping))
- goto out;
+ return 0;
folio_batch_init(&fbatch);
index = start;
if (dax_mapping(mapping)) {
unmap_mapping_pages(mapping, start, end - start + 1, false);
}
-out:
- cleancache_invalidate_inode(mapping);
return ret;
}
EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
projects / platform / kernel / linux-starfive.git / commitdiff