linux/fs/nfs/nfs42xattr.c
Nhat Pham 0a97c01cd2 list_lru: allow explicit memcg and NUMA node selection
Patch series "workload-specific and memory pressure-driven zswap
writeback", v8.

There are currently several issues with zswap writeback:

1. There is only a single global LRU for zswap, making it impossible to
   perform worload-specific shrinking - an memcg under memory pressure
   cannot determine which pages in the pool it owns, and often ends up
   writing pages from other memcgs. This issue has been previously
   observed in practice and mitigated by simply disabling
   memcg-initiated shrinking:

   https://lore.kernel.org/all/20230530232435.3097106-1-nphamcs@gmail.com/T/#u

   But this solution leaves a lot to be desired, as we still do not
   have an avenue for an memcg to free up its own memory locked up in
   the zswap pool.

2. We only shrink the zswap pool when the user-defined limit is hit.
   This means that if we set the limit too high, cold data that are
   unlikely to be used again will reside in the pool, wasting precious
   memory. It is hard to predict how much zswap space will be needed
   ahead of time, as this depends on the workload (specifically, on
   factors such as memory access patterns and compressibility of the
   memory pages).

This patch series solves these issues by separating the global zswap LRU
into per-memcg and per-NUMA LRUs, and performs workload-specific (i.e
memcg- and NUMA-aware) zswap writeback under memory pressure.  The new
shrinker does not have any parameter that must be tuned by the user, and
can be opted in or out on a per-memcg basis.

As a proof of concept, we ran the following synthetic benchmark: build the
linux kernel in a memory-limited cgroup, and allocate some cold data in
tmpfs to see if the shrinker could write them out and improved the overall
performance.  Depending on the amount of cold data generated, we observe
from 14% to 35% reduction in kernel CPU time used in the kernel builds.


This patch (of 6):

The interface of list_lru is based on the assumption that the list node
and the data it represents belong to the same allocated on the correct
node/memcg.  While this assumption is valid for existing slab objects LRU
such as dentries and inodes, it is undocumented, and rather inflexible for
certain potential list_lru users (such as the upcoming zswap shrinker and
the THP shrinker).  It has caused us a lot of issues during our
development.

This patch changes list_lru interface so that the caller must explicitly
specify numa node and memcg when adding and removing objects.  The old
list_lru_add() and list_lru_del() are renamed to list_lru_add_obj() and
list_lru_del_obj(), respectively.

It also extends the list_lru API with a new function, list_lru_putback,
which undoes a previous list_lru_isolate call.  Unlike list_lru_add, it
does not increment the LRU node count (as list_lru_isolate does not
decrement the node count).  list_lru_putback also allows for explicit
memcg and NUMA node selection.

Link: https://lkml.kernel.org/r/20231130194023.4102148-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20231130194023.4102148-2-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-12-12 10:57:01 -08:00

1068 lines
26 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright 2019, 2020 Amazon.com, Inc. or its affiliates. All rights reserved.
*
* User extended attribute client side cache functions.
*
* Author: Frank van der Linden <fllinden@amazon.com>
*/
#include <linux/errno.h>
#include <linux/nfs_fs.h>
#include <linux/hashtable.h>
#include <linux/refcount.h>
#include <uapi/linux/xattr.h>
#include "nfs4_fs.h"
#include "internal.h"
/*
* User extended attributes client side caching is implemented by having
* a cache structure attached to NFS inodes. This structure is allocated
* when needed, and freed when the cache is zapped.
*
* The cache structure contains as hash table of entries, and a pointer
* to a special-cased entry for the listxattr cache.
*
* Accessing and allocating / freeing the caches is done via reference
* counting. The cache entries use a similar refcounting scheme.
*
* This makes freeing a cache, both from the shrinker and from the
* zap cache path, easy. It also means that, in current use cases,
* the large majority of inodes will not waste any memory, as they
* will never have any user extended attributes assigned to them.
*
* Attribute entries are hashed in to a simple hash table. They are
* also part of an LRU.
*
* There are three shrinkers.
*
* Two shrinkers deal with the cache entries themselves: one for
* large entries (> PAGE_SIZE), and one for smaller entries. The
* shrinker for the larger entries works more aggressively than
* those for the smaller entries.
*
* The other shrinker frees the cache structures themselves.
*/
/*
* 64 buckets is a good default. There is likely no reasonable
* workload that uses more than even 64 user extended attributes.
* You can certainly add a lot more - but you get what you ask for
* in those circumstances.
*/
#define NFS4_XATTR_HASH_SIZE 64
#define NFSDBG_FACILITY NFSDBG_XATTRCACHE
struct nfs4_xattr_cache;
struct nfs4_xattr_entry;
struct nfs4_xattr_bucket {
spinlock_t lock;
struct hlist_head hlist;
struct nfs4_xattr_cache *cache;
bool draining;
};
struct nfs4_xattr_cache {
struct kref ref;
struct nfs4_xattr_bucket buckets[NFS4_XATTR_HASH_SIZE];
struct list_head lru;
struct list_head dispose;
atomic_long_t nent;
spinlock_t listxattr_lock;
struct inode *inode;
struct nfs4_xattr_entry *listxattr;
};
struct nfs4_xattr_entry {
struct kref ref;
struct hlist_node hnode;
struct list_head lru;
struct list_head dispose;
char *xattr_name;
void *xattr_value;
size_t xattr_size;
struct nfs4_xattr_bucket *bucket;
uint32_t flags;
};
#define NFS4_XATTR_ENTRY_EXTVAL 0x0001
/*
* LRU list of NFS inodes that have xattr caches.
*/
static struct list_lru nfs4_xattr_cache_lru;
static struct list_lru nfs4_xattr_entry_lru;
static struct list_lru nfs4_xattr_large_entry_lru;
static struct kmem_cache *nfs4_xattr_cache_cachep;
/*
* Hashing helper functions.
*/
static void
nfs4_xattr_hash_init(struct nfs4_xattr_cache *cache)
{
unsigned int i;
for (i = 0; i < NFS4_XATTR_HASH_SIZE; i++) {
INIT_HLIST_HEAD(&cache->buckets[i].hlist);
spin_lock_init(&cache->buckets[i].lock);
cache->buckets[i].cache = cache;
cache->buckets[i].draining = false;
}
}
/*
* Locking order:
* 1. inode i_lock or bucket lock
* 2. list_lru lock (taken by list_lru_* functions)
*/
/*
* Wrapper functions to add a cache entry to the right LRU.
*/
static bool
nfs4_xattr_entry_lru_add(struct nfs4_xattr_entry *entry)
{
struct list_lru *lru;
lru = (entry->flags & NFS4_XATTR_ENTRY_EXTVAL) ?
&nfs4_xattr_large_entry_lru : &nfs4_xattr_entry_lru;
return list_lru_add_obj(lru, &entry->lru);
}
static bool
nfs4_xattr_entry_lru_del(struct nfs4_xattr_entry *entry)
{
struct list_lru *lru;
lru = (entry->flags & NFS4_XATTR_ENTRY_EXTVAL) ?
&nfs4_xattr_large_entry_lru : &nfs4_xattr_entry_lru;
return list_lru_del_obj(lru, &entry->lru);
}
/*
* This function allocates cache entries. They are the normal
* extended attribute name/value pairs, but may also be a listxattr
* cache. Those allocations use the same entry so that they can be
* treated as one by the memory shrinker.
*
* xattr cache entries are allocated together with names. If the
* value fits in to one page with the entry structure and the name,
* it will also be part of the same allocation (kmalloc). This is
* expected to be the vast majority of cases. Larger allocations
* have a value pointer that is allocated separately by kvmalloc.
*
* Parameters:
*
* @name: Name of the extended attribute. NULL for listxattr cache
* entry.
* @value: Value of attribute, or listxattr cache. NULL if the
* value is to be copied from pages instead.
* @pages: Pages to copy the value from, if not NULL. Passed in to
* make it easier to copy the value after an RPC, even if
* the value will not be passed up to application (e.g.
* for a 'query' getxattr with NULL buffer).
* @len: Length of the value. Can be 0 for zero-length attributes.
* @value and @pages will be NULL if @len is 0.
*/
static struct nfs4_xattr_entry *
nfs4_xattr_alloc_entry(const char *name, const void *value,
struct page **pages, size_t len)
{
struct nfs4_xattr_entry *entry;
void *valp;
char *namep;
size_t alloclen, slen;
char *buf;
uint32_t flags;
BUILD_BUG_ON(sizeof(struct nfs4_xattr_entry) +
XATTR_NAME_MAX + 1 > PAGE_SIZE);
alloclen = sizeof(struct nfs4_xattr_entry);
if (name != NULL) {
slen = strlen(name) + 1;
alloclen += slen;
} else
slen = 0;
if (alloclen + len <= PAGE_SIZE) {
alloclen += len;
flags = 0;
} else {
flags = NFS4_XATTR_ENTRY_EXTVAL;
}
buf = kmalloc(alloclen, GFP_KERNEL);
if (buf == NULL)
return NULL;
entry = (struct nfs4_xattr_entry *)buf;
if (name != NULL) {
namep = buf + sizeof(struct nfs4_xattr_entry);
memcpy(namep, name, slen);
} else {
namep = NULL;
}
if (flags & NFS4_XATTR_ENTRY_EXTVAL) {
valp = kvmalloc(len, GFP_KERNEL);
if (valp == NULL) {
kfree(buf);
return NULL;
}
} else if (len != 0) {
valp = buf + sizeof(struct nfs4_xattr_entry) + slen;
} else
valp = NULL;
if (valp != NULL) {
if (value != NULL)
memcpy(valp, value, len);
else
_copy_from_pages(valp, pages, 0, len);
}
entry->flags = flags;
entry->xattr_value = valp;
kref_init(&entry->ref);
entry->xattr_name = namep;
entry->xattr_size = len;
entry->bucket = NULL;
INIT_LIST_HEAD(&entry->lru);
INIT_LIST_HEAD(&entry->dispose);
INIT_HLIST_NODE(&entry->hnode);
return entry;
}
static void
nfs4_xattr_free_entry(struct nfs4_xattr_entry *entry)
{
if (entry->flags & NFS4_XATTR_ENTRY_EXTVAL)
kvfree(entry->xattr_value);
kfree(entry);
}
static void
nfs4_xattr_free_entry_cb(struct kref *kref)
{
struct nfs4_xattr_entry *entry;
entry = container_of(kref, struct nfs4_xattr_entry, ref);
if (WARN_ON(!list_empty(&entry->lru)))
return;
nfs4_xattr_free_entry(entry);
}
static void
nfs4_xattr_free_cache_cb(struct kref *kref)
{
struct nfs4_xattr_cache *cache;
int i;
cache = container_of(kref, struct nfs4_xattr_cache, ref);
for (i = 0; i < NFS4_XATTR_HASH_SIZE; i++) {
if (WARN_ON(!hlist_empty(&cache->buckets[i].hlist)))
return;
cache->buckets[i].draining = false;
}
cache->listxattr = NULL;
kmem_cache_free(nfs4_xattr_cache_cachep, cache);
}
static struct nfs4_xattr_cache *
nfs4_xattr_alloc_cache(void)
{
struct nfs4_xattr_cache *cache;
cache = kmem_cache_alloc(nfs4_xattr_cache_cachep, GFP_KERNEL);
if (cache == NULL)
return NULL;
kref_init(&cache->ref);
atomic_long_set(&cache->nent, 0);
return cache;
}
/*
* Set the listxattr cache, which is a special-cased cache entry.
* The special value ERR_PTR(-ESTALE) is used to indicate that
* the cache is being drained - this prevents a new listxattr
* cache from being added to what is now a stale cache.
*/
static int
nfs4_xattr_set_listcache(struct nfs4_xattr_cache *cache,
struct nfs4_xattr_entry *new)
{
struct nfs4_xattr_entry *old;
int ret = 1;
spin_lock(&cache->listxattr_lock);
old = cache->listxattr;
if (old == ERR_PTR(-ESTALE)) {
ret = 0;
goto out;
}
cache->listxattr = new;
if (new != NULL && new != ERR_PTR(-ESTALE))
nfs4_xattr_entry_lru_add(new);
if (old != NULL) {
nfs4_xattr_entry_lru_del(old);
kref_put(&old->ref, nfs4_xattr_free_entry_cb);
}
out:
spin_unlock(&cache->listxattr_lock);
return ret;
}
/*
* Unlink a cache from its parent inode, clearing out an invalid
* cache. Must be called with i_lock held.
*/
static struct nfs4_xattr_cache *
nfs4_xattr_cache_unlink(struct inode *inode)
{
struct nfs_inode *nfsi;
struct nfs4_xattr_cache *oldcache;
nfsi = NFS_I(inode);
oldcache = nfsi->xattr_cache;
if (oldcache != NULL) {
list_lru_del_obj(&nfs4_xattr_cache_lru, &oldcache->lru);
oldcache->inode = NULL;
}
nfsi->xattr_cache = NULL;
nfsi->cache_validity &= ~NFS_INO_INVALID_XATTR;
return oldcache;
}
/*
* Discard a cache. Called by get_cache() if there was an old,
* invalid cache. Can also be called from a shrinker callback.
*
* The cache is dead, it has already been unlinked from its inode,
* and no longer appears on the cache LRU list.
*
* Mark all buckets as draining, so that no new entries are added. This
* could still happen in the unlikely, but possible case that another
* thread had grabbed a reference before it was unlinked from the inode,
* and is still holding it for an add operation.
*
* Remove all entries from the LRU lists, so that there is no longer
* any way to 'find' this cache. Then, remove the entries from the hash
* table.
*
* At that point, the cache will remain empty and can be freed when the final
* reference drops, which is very likely the kref_put at the end of
* this function, or the one called immediately afterwards in the
* shrinker callback.
*/
static void
nfs4_xattr_discard_cache(struct nfs4_xattr_cache *cache)
{
unsigned int i;
struct nfs4_xattr_entry *entry;
struct nfs4_xattr_bucket *bucket;
struct hlist_node *n;
nfs4_xattr_set_listcache(cache, ERR_PTR(-ESTALE));
for (i = 0; i < NFS4_XATTR_HASH_SIZE; i++) {
bucket = &cache->buckets[i];
spin_lock(&bucket->lock);
bucket->draining = true;
hlist_for_each_entry_safe(entry, n, &bucket->hlist, hnode) {
nfs4_xattr_entry_lru_del(entry);
hlist_del_init(&entry->hnode);
kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
}
spin_unlock(&bucket->lock);
}
atomic_long_set(&cache->nent, 0);
kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
}
/*
* Get a referenced copy of the cache structure. Avoid doing allocs
* while holding i_lock. Which means that we do some optimistic allocation,
* and might have to free the result in rare cases.
*
* This function only checks the NFS_INO_INVALID_XATTR cache validity bit
* and acts accordingly, replacing the cache when needed. For the read case
* (!add), this means that the caller must make sure that the cache
* is valid before caling this function. getxattr and listxattr call
* revalidate_inode to do this. The attribute cache timeout (for the
* non-delegated case) is expected to be dealt with in the revalidate
* call.
*/
static struct nfs4_xattr_cache *
nfs4_xattr_get_cache(struct inode *inode, int add)
{
struct nfs_inode *nfsi;
struct nfs4_xattr_cache *cache, *oldcache, *newcache;
nfsi = NFS_I(inode);
cache = oldcache = NULL;
spin_lock(&inode->i_lock);
if (nfsi->cache_validity & NFS_INO_INVALID_XATTR)
oldcache = nfs4_xattr_cache_unlink(inode);
else
cache = nfsi->xattr_cache;
if (cache != NULL)
kref_get(&cache->ref);
spin_unlock(&inode->i_lock);
if (add && cache == NULL) {
newcache = NULL;
cache = nfs4_xattr_alloc_cache();
if (cache == NULL)
goto out;
spin_lock(&inode->i_lock);
if (nfsi->cache_validity & NFS_INO_INVALID_XATTR) {
/*
* The cache was invalidated again. Give up,
* since what we want to enter is now likely
* outdated anyway.
*/
spin_unlock(&inode->i_lock);
kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
cache = NULL;
goto out;
}
/*
* Check if someone beat us to it.
*/
if (nfsi->xattr_cache != NULL) {
newcache = nfsi->xattr_cache;
kref_get(&newcache->ref);
} else {
kref_get(&cache->ref);
nfsi->xattr_cache = cache;
cache->inode = inode;
list_lru_add_obj(&nfs4_xattr_cache_lru, &cache->lru);
}
spin_unlock(&inode->i_lock);
/*
* If there was a race, throw away the cache we just
* allocated, and use the new one allocated by someone
* else.
*/
if (newcache != NULL) {
kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
cache = newcache;
}
}
out:
/*
* Discard the now orphaned old cache.
*/
if (oldcache != NULL)
nfs4_xattr_discard_cache(oldcache);
return cache;
}
static inline struct nfs4_xattr_bucket *
nfs4_xattr_hash_bucket(struct nfs4_xattr_cache *cache, const char *name)
{
return &cache->buckets[jhash(name, strlen(name), 0) &
(ARRAY_SIZE(cache->buckets) - 1)];
}
static struct nfs4_xattr_entry *
nfs4_xattr_get_entry(struct nfs4_xattr_bucket *bucket, const char *name)
{
struct nfs4_xattr_entry *entry;
entry = NULL;
hlist_for_each_entry(entry, &bucket->hlist, hnode) {
if (!strcmp(entry->xattr_name, name))
break;
}
return entry;
}
static int
nfs4_xattr_hash_add(struct nfs4_xattr_cache *cache,
struct nfs4_xattr_entry *entry)
{
struct nfs4_xattr_bucket *bucket;
struct nfs4_xattr_entry *oldentry = NULL;
int ret = 1;
bucket = nfs4_xattr_hash_bucket(cache, entry->xattr_name);
entry->bucket = bucket;
spin_lock(&bucket->lock);
if (bucket->draining) {
ret = 0;
goto out;
}
oldentry = nfs4_xattr_get_entry(bucket, entry->xattr_name);
if (oldentry != NULL) {
hlist_del_init(&oldentry->hnode);
nfs4_xattr_entry_lru_del(oldentry);
} else {
atomic_long_inc(&cache->nent);
}
hlist_add_head(&entry->hnode, &bucket->hlist);
nfs4_xattr_entry_lru_add(entry);
out:
spin_unlock(&bucket->lock);
if (oldentry != NULL)
kref_put(&oldentry->ref, nfs4_xattr_free_entry_cb);
return ret;
}
static void
nfs4_xattr_hash_remove(struct nfs4_xattr_cache *cache, const char *name)
{
struct nfs4_xattr_bucket *bucket;
struct nfs4_xattr_entry *entry;
bucket = nfs4_xattr_hash_bucket(cache, name);
spin_lock(&bucket->lock);
entry = nfs4_xattr_get_entry(bucket, name);
if (entry != NULL) {
hlist_del_init(&entry->hnode);
nfs4_xattr_entry_lru_del(entry);
atomic_long_dec(&cache->nent);
}
spin_unlock(&bucket->lock);
if (entry != NULL)
kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
}
static struct nfs4_xattr_entry *
nfs4_xattr_hash_find(struct nfs4_xattr_cache *cache, const char *name)
{
struct nfs4_xattr_bucket *bucket;
struct nfs4_xattr_entry *entry;
bucket = nfs4_xattr_hash_bucket(cache, name);
spin_lock(&bucket->lock);
entry = nfs4_xattr_get_entry(bucket, name);
if (entry != NULL)
kref_get(&entry->ref);
spin_unlock(&bucket->lock);
return entry;
}
/*
* Entry point to retrieve an entry from the cache.
*/
ssize_t nfs4_xattr_cache_get(struct inode *inode, const char *name, char *buf,
ssize_t buflen)
{
struct nfs4_xattr_cache *cache;
struct nfs4_xattr_entry *entry;
ssize_t ret;
cache = nfs4_xattr_get_cache(inode, 0);
if (cache == NULL)
return -ENOENT;
ret = 0;
entry = nfs4_xattr_hash_find(cache, name);
if (entry != NULL) {
dprintk("%s: cache hit '%s', len %lu\n", __func__,
entry->xattr_name, (unsigned long)entry->xattr_size);
if (buflen == 0) {
/* Length probe only */
ret = entry->xattr_size;
} else if (buflen < entry->xattr_size)
ret = -ERANGE;
else {
memcpy(buf, entry->xattr_value, entry->xattr_size);
ret = entry->xattr_size;
}
kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
} else {
dprintk("%s: cache miss '%s'\n", __func__, name);
ret = -ENOENT;
}
kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
return ret;
}
/*
* Retrieve a cached list of xattrs from the cache.
*/
ssize_t nfs4_xattr_cache_list(struct inode *inode, char *buf, ssize_t buflen)
{
struct nfs4_xattr_cache *cache;
struct nfs4_xattr_entry *entry;
ssize_t ret;
cache = nfs4_xattr_get_cache(inode, 0);
if (cache == NULL)
return -ENOENT;
spin_lock(&cache->listxattr_lock);
entry = cache->listxattr;
if (entry != NULL && entry != ERR_PTR(-ESTALE)) {
if (buflen == 0) {
/* Length probe only */
ret = entry->xattr_size;
} else if (entry->xattr_size > buflen)
ret = -ERANGE;
else {
memcpy(buf, entry->xattr_value, entry->xattr_size);
ret = entry->xattr_size;
}
} else {
ret = -ENOENT;
}
spin_unlock(&cache->listxattr_lock);
kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
return ret;
}
/*
* Add an xattr to the cache.
*
* This also invalidates the xattr list cache.
*/
void nfs4_xattr_cache_add(struct inode *inode, const char *name,
const char *buf, struct page **pages, ssize_t buflen)
{
struct nfs4_xattr_cache *cache;
struct nfs4_xattr_entry *entry;
dprintk("%s: add '%s' len %lu\n", __func__,
name, (unsigned long)buflen);
cache = nfs4_xattr_get_cache(inode, 1);
if (cache == NULL)
return;
entry = nfs4_xattr_alloc_entry(name, buf, pages, buflen);
if (entry == NULL)
goto out;
(void)nfs4_xattr_set_listcache(cache, NULL);
if (!nfs4_xattr_hash_add(cache, entry))
kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
out:
kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
}
/*
* Remove an xattr from the cache.
*
* This also invalidates the xattr list cache.
*/
void nfs4_xattr_cache_remove(struct inode *inode, const char *name)
{
struct nfs4_xattr_cache *cache;
dprintk("%s: remove '%s'\n", __func__, name);
cache = nfs4_xattr_get_cache(inode, 0);
if (cache == NULL)
return;
(void)nfs4_xattr_set_listcache(cache, NULL);
nfs4_xattr_hash_remove(cache, name);
kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
}
/*
* Cache listxattr output, replacing any possible old one.
*/
void nfs4_xattr_cache_set_list(struct inode *inode, const char *buf,
ssize_t buflen)
{
struct nfs4_xattr_cache *cache;
struct nfs4_xattr_entry *entry;
cache = nfs4_xattr_get_cache(inode, 1);
if (cache == NULL)
return;
entry = nfs4_xattr_alloc_entry(NULL, buf, NULL, buflen);
if (entry == NULL)
goto out;
/*
* This is just there to be able to get to bucket->cache,
* which is obviously the same for all buckets, so just
* use bucket 0.
*/
entry->bucket = &cache->buckets[0];
if (!nfs4_xattr_set_listcache(cache, entry))
kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
out:
kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
}
/*
* Zap the entire cache. Called when an inode is evicted.
*/
void nfs4_xattr_cache_zap(struct inode *inode)
{
struct nfs4_xattr_cache *oldcache;
spin_lock(&inode->i_lock);
oldcache = nfs4_xattr_cache_unlink(inode);
spin_unlock(&inode->i_lock);
if (oldcache)
nfs4_xattr_discard_cache(oldcache);
}
/*
* The entry LRU is shrunk more aggressively than the cache LRU,
* by settings @seeks to 1.
*
* Cache structures are freed only when they've become empty, after
* pruning all but one entry.
*/
static unsigned long nfs4_xattr_cache_count(struct shrinker *shrink,
struct shrink_control *sc);
static unsigned long nfs4_xattr_entry_count(struct shrinker *shrink,
struct shrink_control *sc);
static unsigned long nfs4_xattr_cache_scan(struct shrinker *shrink,
struct shrink_control *sc);
static unsigned long nfs4_xattr_entry_scan(struct shrinker *shrink,
struct shrink_control *sc);
static struct shrinker *nfs4_xattr_cache_shrinker;
static struct shrinker *nfs4_xattr_entry_shrinker;
static struct shrinker *nfs4_xattr_large_entry_shrinker;
static enum lru_status
cache_lru_isolate(struct list_head *item,
struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
{
struct list_head *dispose = arg;
struct inode *inode;
struct nfs4_xattr_cache *cache = container_of(item,
struct nfs4_xattr_cache, lru);
if (atomic_long_read(&cache->nent) > 1)
return LRU_SKIP;
/*
* If a cache structure is on the LRU list, we know that
* its inode is valid. Try to lock it to break the link.
* Since we're inverting the lock order here, only try.
*/
inode = cache->inode;
if (!spin_trylock(&inode->i_lock))
return LRU_SKIP;
kref_get(&cache->ref);
cache->inode = NULL;
NFS_I(inode)->xattr_cache = NULL;
NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_XATTR;
list_lru_isolate(lru, &cache->lru);
spin_unlock(&inode->i_lock);
list_add_tail(&cache->dispose, dispose);
return LRU_REMOVED;
}
static unsigned long
nfs4_xattr_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
{
LIST_HEAD(dispose);
unsigned long freed;
struct nfs4_xattr_cache *cache;
freed = list_lru_shrink_walk(&nfs4_xattr_cache_lru, sc,
cache_lru_isolate, &dispose);
while (!list_empty(&dispose)) {
cache = list_first_entry(&dispose, struct nfs4_xattr_cache,
dispose);
list_del_init(&cache->dispose);
nfs4_xattr_discard_cache(cache);
kref_put(&cache->ref, nfs4_xattr_free_cache_cb);
}
return freed;
}
static unsigned long
nfs4_xattr_cache_count(struct shrinker *shrink, struct shrink_control *sc)
{
unsigned long count;
count = list_lru_shrink_count(&nfs4_xattr_cache_lru, sc);
return vfs_pressure_ratio(count);
}
static enum lru_status
entry_lru_isolate(struct list_head *item,
struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
{
struct list_head *dispose = arg;
struct nfs4_xattr_bucket *bucket;
struct nfs4_xattr_cache *cache;
struct nfs4_xattr_entry *entry = container_of(item,
struct nfs4_xattr_entry, lru);
bucket = entry->bucket;
cache = bucket->cache;
/*
* Unhook the entry from its parent (either a cache bucket
* or a cache structure if it's a listxattr buf), so that
* it's no longer found. Then add it to the isolate list,
* to be freed later.
*
* In both cases, we're reverting lock order, so use
* trylock and skip the entry if we can't get the lock.
*/
if (entry->xattr_name != NULL) {
/* Regular cache entry */
if (!spin_trylock(&bucket->lock))
return LRU_SKIP;
kref_get(&entry->ref);
hlist_del_init(&entry->hnode);
atomic_long_dec(&cache->nent);
list_lru_isolate(lru, &entry->lru);
spin_unlock(&bucket->lock);
} else {
/* Listxattr cache entry */
if (!spin_trylock(&cache->listxattr_lock))
return LRU_SKIP;
kref_get(&entry->ref);
cache->listxattr = NULL;
list_lru_isolate(lru, &entry->lru);
spin_unlock(&cache->listxattr_lock);
}
list_add_tail(&entry->dispose, dispose);
return LRU_REMOVED;
}
static unsigned long
nfs4_xattr_entry_scan(struct shrinker *shrink, struct shrink_control *sc)
{
LIST_HEAD(dispose);
unsigned long freed;
struct nfs4_xattr_entry *entry;
struct list_lru *lru;
lru = (shrink == nfs4_xattr_large_entry_shrinker) ?
&nfs4_xattr_large_entry_lru : &nfs4_xattr_entry_lru;
freed = list_lru_shrink_walk(lru, sc, entry_lru_isolate, &dispose);
while (!list_empty(&dispose)) {
entry = list_first_entry(&dispose, struct nfs4_xattr_entry,
dispose);
list_del_init(&entry->dispose);
/*
* Drop two references: the one that we just grabbed
* in entry_lru_isolate, and the one that was set
* when the entry was first allocated.
*/
kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
kref_put(&entry->ref, nfs4_xattr_free_entry_cb);
}
return freed;
}
static unsigned long
nfs4_xattr_entry_count(struct shrinker *shrink, struct shrink_control *sc)
{
unsigned long count;
struct list_lru *lru;
lru = (shrink == nfs4_xattr_large_entry_shrinker) ?
&nfs4_xattr_large_entry_lru : &nfs4_xattr_entry_lru;
count = list_lru_shrink_count(lru, sc);
return vfs_pressure_ratio(count);
}
static void nfs4_xattr_cache_init_once(void *p)
{
struct nfs4_xattr_cache *cache = p;
spin_lock_init(&cache->listxattr_lock);
atomic_long_set(&cache->nent, 0);
nfs4_xattr_hash_init(cache);
cache->listxattr = NULL;
INIT_LIST_HEAD(&cache->lru);
INIT_LIST_HEAD(&cache->dispose);
}
typedef unsigned long (*count_objects_cb)(struct shrinker *s,
struct shrink_control *sc);
typedef unsigned long (*scan_objects_cb)(struct shrinker *s,
struct shrink_control *sc);
static int __init nfs4_xattr_shrinker_init(struct shrinker **shrinker,
struct list_lru *lru, const char *name,
count_objects_cb count,
scan_objects_cb scan, long batch, int seeks)
{
int ret;
*shrinker = shrinker_alloc(SHRINKER_MEMCG_AWARE, name);
if (!*shrinker)
return -ENOMEM;
ret = list_lru_init_memcg(lru, *shrinker);
if (ret) {
shrinker_free(*shrinker);
return ret;
}
(*shrinker)->count_objects = count;
(*shrinker)->scan_objects = scan;
(*shrinker)->batch = batch;
(*shrinker)->seeks = seeks;
shrinker_register(*shrinker);
return ret;
}
static void nfs4_xattr_shrinker_destroy(struct shrinker *shrinker,
struct list_lru *lru)
{
shrinker_free(shrinker);
list_lru_destroy(lru);
}
int __init nfs4_xattr_cache_init(void)
{
int ret = 0;
nfs4_xattr_cache_cachep = kmem_cache_create("nfs4_xattr_cache_cache",
sizeof(struct nfs4_xattr_cache), 0,
(SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD),
nfs4_xattr_cache_init_once);
if (nfs4_xattr_cache_cachep == NULL)
return -ENOMEM;
ret = nfs4_xattr_shrinker_init(&nfs4_xattr_cache_shrinker,
&nfs4_xattr_cache_lru, "nfs-xattr_cache",
nfs4_xattr_cache_count,
nfs4_xattr_cache_scan, 0, DEFAULT_SEEKS);
if (ret)
goto out1;
ret = nfs4_xattr_shrinker_init(&nfs4_xattr_entry_shrinker,
&nfs4_xattr_entry_lru, "nfs-xattr_entry",
nfs4_xattr_entry_count,
nfs4_xattr_entry_scan, 512, DEFAULT_SEEKS);
if (ret)
goto out2;
ret = nfs4_xattr_shrinker_init(&nfs4_xattr_large_entry_shrinker,
&nfs4_xattr_large_entry_lru,
"nfs-xattr_large_entry",
nfs4_xattr_entry_count,
nfs4_xattr_entry_scan, 512, 1);
if (!ret)
return 0;
nfs4_xattr_shrinker_destroy(nfs4_xattr_entry_shrinker,
&nfs4_xattr_entry_lru);
out2:
nfs4_xattr_shrinker_destroy(nfs4_xattr_cache_shrinker,
&nfs4_xattr_cache_lru);
out1:
kmem_cache_destroy(nfs4_xattr_cache_cachep);
return ret;
}
void nfs4_xattr_cache_exit(void)
{
nfs4_xattr_shrinker_destroy(nfs4_xattr_large_entry_shrinker,
&nfs4_xattr_large_entry_lru);
nfs4_xattr_shrinker_destroy(nfs4_xattr_entry_shrinker,
&nfs4_xattr_entry_lru);
nfs4_xattr_shrinker_destroy(nfs4_xattr_cache_shrinker,
&nfs4_xattr_cache_lru);
kmem_cache_destroy(nfs4_xattr_cache_cachep);
}