linux-stable/fs/nfs/nfs42xattr.c
J. Bruce Fields 70438afbf1 NFSv4.2: fix failure to unregister shrinker
We forgot to unregister the nfs4_xattr_large_entry_shrinker.

That leaves the global list of shrinkers corrupted after unload of the
nfs module, after which possibly unrelated code that calls
register_shrinker() or unregister_shrinker() gets a BUG() with
"supervisor write access in kernel mode".

And similarly for the nfs4_xattr_large_entry_lru.

Reported-by: Kris Karas <bugs-a17@moonlit-rail.com>
Tested-By: Kris Karas <bugs-a17@moonlit-rail.com>
Fixes: 95ad37f90c "NFSv4.2: add client side xattr caching."
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
CC: stable@vger.kernel.org
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
2020-11-12 10:40:02 -05:00

1057 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(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(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 attribues.
* @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_ACCOUNT | GFP_NOFS);
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_ACCOUNT | GFP_NOFS);
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_ACCOUNT | GFP_NOFS);
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(&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(&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 = {
.count_objects = nfs4_xattr_cache_count,
.scan_objects = nfs4_xattr_cache_scan,
.seeks = DEFAULT_SEEKS,
.flags = SHRINKER_MEMCG_AWARE,
};
static struct shrinker nfs4_xattr_entry_shrinker = {
.count_objects = nfs4_xattr_entry_count,
.scan_objects = nfs4_xattr_entry_scan,
.seeks = DEFAULT_SEEKS,
.batch = 512,
.flags = SHRINKER_MEMCG_AWARE,
};
static struct shrinker nfs4_xattr_large_entry_shrinker = {
.count_objects = nfs4_xattr_entry_count,
.scan_objects = nfs4_xattr_entry_scan,
.seeks = 1,
.batch = 512,
.flags = SHRINKER_MEMCG_AWARE,
};
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 = (struct nfs4_xattr_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);
}
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|SLAB_ACCOUNT),
nfs4_xattr_cache_init_once);
if (nfs4_xattr_cache_cachep == NULL)
return -ENOMEM;
ret = list_lru_init_memcg(&nfs4_xattr_large_entry_lru,
&nfs4_xattr_large_entry_shrinker);
if (ret)
goto out4;
ret = list_lru_init_memcg(&nfs4_xattr_entry_lru,
&nfs4_xattr_entry_shrinker);
if (ret)
goto out3;
ret = list_lru_init_memcg(&nfs4_xattr_cache_lru,
&nfs4_xattr_cache_shrinker);
if (ret)
goto out2;
ret = register_shrinker(&nfs4_xattr_cache_shrinker);
if (ret)
goto out1;
ret = register_shrinker(&nfs4_xattr_entry_shrinker);
if (ret)
goto out;
ret = register_shrinker(&nfs4_xattr_large_entry_shrinker);
if (!ret)
return 0;
unregister_shrinker(&nfs4_xattr_entry_shrinker);
out:
unregister_shrinker(&nfs4_xattr_cache_shrinker);
out1:
list_lru_destroy(&nfs4_xattr_cache_lru);
out2:
list_lru_destroy(&nfs4_xattr_entry_lru);
out3:
list_lru_destroy(&nfs4_xattr_large_entry_lru);
out4:
kmem_cache_destroy(nfs4_xattr_cache_cachep);
return ret;
}
void nfs4_xattr_cache_exit(void)
{
unregister_shrinker(&nfs4_xattr_large_entry_shrinker);
unregister_shrinker(&nfs4_xattr_entry_shrinker);
unregister_shrinker(&nfs4_xattr_cache_shrinker);
list_lru_destroy(&nfs4_xattr_large_entry_lru);
list_lru_destroy(&nfs4_xattr_entry_lru);
list_lru_destroy(&nfs4_xattr_cache_lru);
kmem_cache_destroy(nfs4_xattr_cache_cachep);
}