swh:1:snp:173f8deb0c56c557784b4fd217e7608ac6197844
Tip revision: 11a48a5a18c63fd7621bb050228cebf13566e4d8 authored by Linus Torvalds on 16 February 2020, 21:16:59 UTC
Linux 5.6-rc2
Linux 5.6-rc2
Tip revision: 11a48a5
filecache.c
/*
* Open file cache.
*
* (c) 2015 - Jeff Layton <jeff.layton@primarydata.com>
*/
#include <linux/hash.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/sched.h>
#include <linux/list_lru.h>
#include <linux/fsnotify_backend.h>
#include <linux/fsnotify.h>
#include <linux/seq_file.h>
#include "vfs.h"
#include "nfsd.h"
#include "nfsfh.h"
#include "netns.h"
#include "filecache.h"
#include "trace.h"
#define NFSDDBG_FACILITY NFSDDBG_FH
/* FIXME: dynamically size this for the machine somehow? */
#define NFSD_FILE_HASH_BITS 12
#define NFSD_FILE_HASH_SIZE (1 << NFSD_FILE_HASH_BITS)
#define NFSD_LAUNDRETTE_DELAY (2 * HZ)
#define NFSD_FILE_SHUTDOWN (1)
#define NFSD_FILE_LRU_THRESHOLD (4096UL)
#define NFSD_FILE_LRU_LIMIT (NFSD_FILE_LRU_THRESHOLD << 2)
/* We only care about NFSD_MAY_READ/WRITE for this cache */
#define NFSD_FILE_MAY_MASK (NFSD_MAY_READ|NFSD_MAY_WRITE)
struct nfsd_fcache_bucket {
struct hlist_head nfb_head;
spinlock_t nfb_lock;
unsigned int nfb_count;
unsigned int nfb_maxcount;
};
static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits);
struct nfsd_fcache_disposal {
struct list_head list;
struct work_struct work;
struct net *net;
spinlock_t lock;
struct list_head freeme;
struct rcu_head rcu;
};
static struct workqueue_struct *nfsd_filecache_wq __read_mostly;
static struct kmem_cache *nfsd_file_slab;
static struct kmem_cache *nfsd_file_mark_slab;
static struct nfsd_fcache_bucket *nfsd_file_hashtbl;
static struct list_lru nfsd_file_lru;
static long nfsd_file_lru_flags;
static struct fsnotify_group *nfsd_file_fsnotify_group;
static atomic_long_t nfsd_filecache_count;
static struct delayed_work nfsd_filecache_laundrette;
static DEFINE_SPINLOCK(laundrette_lock);
static LIST_HEAD(laundrettes);
static void nfsd_file_gc(void);
static void
nfsd_file_schedule_laundrette(void)
{
long count = atomic_long_read(&nfsd_filecache_count);
if (count == 0 || test_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags))
return;
queue_delayed_work(system_wq, &nfsd_filecache_laundrette,
NFSD_LAUNDRETTE_DELAY);
}
static void
nfsd_file_slab_free(struct rcu_head *rcu)
{
struct nfsd_file *nf = container_of(rcu, struct nfsd_file, nf_rcu);
put_cred(nf->nf_cred);
kmem_cache_free(nfsd_file_slab, nf);
}
static void
nfsd_file_mark_free(struct fsnotify_mark *mark)
{
struct nfsd_file_mark *nfm = container_of(mark, struct nfsd_file_mark,
nfm_mark);
kmem_cache_free(nfsd_file_mark_slab, nfm);
}
static struct nfsd_file_mark *
nfsd_file_mark_get(struct nfsd_file_mark *nfm)
{
if (!refcount_inc_not_zero(&nfm->nfm_ref))
return NULL;
return nfm;
}
static void
nfsd_file_mark_put(struct nfsd_file_mark *nfm)
{
if (refcount_dec_and_test(&nfm->nfm_ref)) {
fsnotify_destroy_mark(&nfm->nfm_mark, nfsd_file_fsnotify_group);
fsnotify_put_mark(&nfm->nfm_mark);
}
}
static struct nfsd_file_mark *
nfsd_file_mark_find_or_create(struct nfsd_file *nf)
{
int err;
struct fsnotify_mark *mark;
struct nfsd_file_mark *nfm = NULL, *new;
struct inode *inode = nf->nf_inode;
do {
mutex_lock(&nfsd_file_fsnotify_group->mark_mutex);
mark = fsnotify_find_mark(&inode->i_fsnotify_marks,
nfsd_file_fsnotify_group);
if (mark) {
nfm = nfsd_file_mark_get(container_of(mark,
struct nfsd_file_mark,
nfm_mark));
mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex);
if (nfm) {
fsnotify_put_mark(mark);
break;
}
/* Avoid soft lockup race with nfsd_file_mark_put() */
fsnotify_destroy_mark(mark, nfsd_file_fsnotify_group);
fsnotify_put_mark(mark);
} else
mutex_unlock(&nfsd_file_fsnotify_group->mark_mutex);
/* allocate a new nfm */
new = kmem_cache_alloc(nfsd_file_mark_slab, GFP_KERNEL);
if (!new)
return NULL;
fsnotify_init_mark(&new->nfm_mark, nfsd_file_fsnotify_group);
new->nfm_mark.mask = FS_ATTRIB|FS_DELETE_SELF;
refcount_set(&new->nfm_ref, 1);
err = fsnotify_add_inode_mark(&new->nfm_mark, inode, 0);
/*
* If the add was successful, then return the object.
* Otherwise, we need to put the reference we hold on the
* nfm_mark. The fsnotify code will take a reference and put
* it on failure, so we can't just free it directly. It's also
* not safe to call fsnotify_destroy_mark on it as the
* mark->group will be NULL. Thus, we can't let the nfm_ref
* counter drive the destruction at this point.
*/
if (likely(!err))
nfm = new;
else
fsnotify_put_mark(&new->nfm_mark);
} while (unlikely(err == -EEXIST));
return nfm;
}
static struct nfsd_file *
nfsd_file_alloc(struct inode *inode, unsigned int may, unsigned int hashval,
struct net *net)
{
struct nfsd_file *nf;
nf = kmem_cache_alloc(nfsd_file_slab, GFP_KERNEL);
if (nf) {
INIT_HLIST_NODE(&nf->nf_node);
INIT_LIST_HEAD(&nf->nf_lru);
nf->nf_file = NULL;
nf->nf_cred = get_current_cred();
nf->nf_net = net;
nf->nf_flags = 0;
nf->nf_inode = inode;
nf->nf_hashval = hashval;
refcount_set(&nf->nf_ref, 1);
nf->nf_may = may & NFSD_FILE_MAY_MASK;
if (may & NFSD_MAY_NOT_BREAK_LEASE) {
if (may & NFSD_MAY_WRITE)
__set_bit(NFSD_FILE_BREAK_WRITE, &nf->nf_flags);
if (may & NFSD_MAY_READ)
__set_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags);
}
nf->nf_mark = NULL;
init_rwsem(&nf->nf_rwsem);
trace_nfsd_file_alloc(nf);
}
return nf;
}
static bool
nfsd_file_free(struct nfsd_file *nf)
{
bool flush = false;
trace_nfsd_file_put_final(nf);
if (nf->nf_mark)
nfsd_file_mark_put(nf->nf_mark);
if (nf->nf_file) {
get_file(nf->nf_file);
filp_close(nf->nf_file, NULL);
fput(nf->nf_file);
flush = true;
}
call_rcu(&nf->nf_rcu, nfsd_file_slab_free);
return flush;
}
static bool
nfsd_file_check_writeback(struct nfsd_file *nf)
{
struct file *file = nf->nf_file;
struct address_space *mapping;
if (!file || !(file->f_mode & FMODE_WRITE))
return false;
mapping = file->f_mapping;
return mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) ||
mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK);
}
static int
nfsd_file_check_write_error(struct nfsd_file *nf)
{
struct file *file = nf->nf_file;
if (!file || !(file->f_mode & FMODE_WRITE))
return 0;
return filemap_check_wb_err(file->f_mapping, READ_ONCE(file->f_wb_err));
}
static void
nfsd_file_do_unhash(struct nfsd_file *nf)
{
lockdep_assert_held(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
trace_nfsd_file_unhash(nf);
if (nfsd_file_check_write_error(nf))
nfsd_reset_boot_verifier(net_generic(nf->nf_net, nfsd_net_id));
--nfsd_file_hashtbl[nf->nf_hashval].nfb_count;
hlist_del_rcu(&nf->nf_node);
atomic_long_dec(&nfsd_filecache_count);
}
static bool
nfsd_file_unhash(struct nfsd_file *nf)
{
if (test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
nfsd_file_do_unhash(nf);
if (!list_empty(&nf->nf_lru))
list_lru_del(&nfsd_file_lru, &nf->nf_lru);
return true;
}
return false;
}
/*
* Return true if the file was unhashed.
*/
static bool
nfsd_file_unhash_and_release_locked(struct nfsd_file *nf, struct list_head *dispose)
{
lockdep_assert_held(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
trace_nfsd_file_unhash_and_release_locked(nf);
if (!nfsd_file_unhash(nf))
return false;
/* keep final reference for nfsd_file_lru_dispose */
if (refcount_dec_not_one(&nf->nf_ref))
return true;
list_add(&nf->nf_lru, dispose);
return true;
}
static void
nfsd_file_put_noref(struct nfsd_file *nf)
{
trace_nfsd_file_put(nf);
if (refcount_dec_and_test(&nf->nf_ref)) {
WARN_ON(test_bit(NFSD_FILE_HASHED, &nf->nf_flags));
nfsd_file_free(nf);
}
}
void
nfsd_file_put(struct nfsd_file *nf)
{
bool is_hashed;
set_bit(NFSD_FILE_REFERENCED, &nf->nf_flags);
if (refcount_read(&nf->nf_ref) > 2 || !nf->nf_file) {
nfsd_file_put_noref(nf);
return;
}
filemap_flush(nf->nf_file->f_mapping);
is_hashed = test_bit(NFSD_FILE_HASHED, &nf->nf_flags) != 0;
nfsd_file_put_noref(nf);
if (is_hashed)
nfsd_file_schedule_laundrette();
if (atomic_long_read(&nfsd_filecache_count) >= NFSD_FILE_LRU_LIMIT)
nfsd_file_gc();
}
struct nfsd_file *
nfsd_file_get(struct nfsd_file *nf)
{
if (likely(refcount_inc_not_zero(&nf->nf_ref)))
return nf;
return NULL;
}
static void
nfsd_file_dispose_list(struct list_head *dispose)
{
struct nfsd_file *nf;
while(!list_empty(dispose)) {
nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
list_del(&nf->nf_lru);
nfsd_file_put_noref(nf);
}
}
static void
nfsd_file_dispose_list_sync(struct list_head *dispose)
{
bool flush = false;
struct nfsd_file *nf;
while(!list_empty(dispose)) {
nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
list_del(&nf->nf_lru);
if (!refcount_dec_and_test(&nf->nf_ref))
continue;
if (nfsd_file_free(nf))
flush = true;
}
if (flush)
flush_delayed_fput();
}
static void
nfsd_file_list_remove_disposal(struct list_head *dst,
struct nfsd_fcache_disposal *l)
{
spin_lock(&l->lock);
list_splice_init(&l->freeme, dst);
spin_unlock(&l->lock);
}
static void
nfsd_file_list_add_disposal(struct list_head *files, struct net *net)
{
struct nfsd_fcache_disposal *l;
rcu_read_lock();
list_for_each_entry_rcu(l, &laundrettes, list) {
if (l->net == net) {
spin_lock(&l->lock);
list_splice_tail_init(files, &l->freeme);
spin_unlock(&l->lock);
queue_work(nfsd_filecache_wq, &l->work);
break;
}
}
rcu_read_unlock();
}
static void
nfsd_file_list_add_pernet(struct list_head *dst, struct list_head *src,
struct net *net)
{
struct nfsd_file *nf, *tmp;
list_for_each_entry_safe(nf, tmp, src, nf_lru) {
if (nf->nf_net == net)
list_move_tail(&nf->nf_lru, dst);
}
}
static void
nfsd_file_dispose_list_delayed(struct list_head *dispose)
{
LIST_HEAD(list);
struct nfsd_file *nf;
while(!list_empty(dispose)) {
nf = list_first_entry(dispose, struct nfsd_file, nf_lru);
nfsd_file_list_add_pernet(&list, dispose, nf->nf_net);
nfsd_file_list_add_disposal(&list, nf->nf_net);
}
}
/*
* Note this can deadlock with nfsd_file_cache_purge.
*/
static enum lru_status
nfsd_file_lru_cb(struct list_head *item, struct list_lru_one *lru,
spinlock_t *lock, void *arg)
__releases(lock)
__acquires(lock)
{
struct list_head *head = arg;
struct nfsd_file *nf = list_entry(item, struct nfsd_file, nf_lru);
/*
* Do a lockless refcount check. The hashtable holds one reference, so
* we look to see if anything else has a reference, or if any have
* been put since the shrinker last ran. Those don't get unhashed and
* released.
*
* Note that in the put path, we set the flag and then decrement the
* counter. Here we check the counter and then test and clear the flag.
* That order is deliberate to ensure that we can do this locklessly.
*/
if (refcount_read(&nf->nf_ref) > 1)
goto out_skip;
/*
* Don't throw out files that are still undergoing I/O or
* that have uncleared errors pending.
*/
if (nfsd_file_check_writeback(nf))
goto out_skip;
if (test_and_clear_bit(NFSD_FILE_REFERENCED, &nf->nf_flags))
goto out_skip;
if (!test_and_clear_bit(NFSD_FILE_HASHED, &nf->nf_flags))
goto out_skip;
list_lru_isolate_move(lru, &nf->nf_lru, head);
return LRU_REMOVED;
out_skip:
return LRU_SKIP;
}
static unsigned long
nfsd_file_lru_walk_list(struct shrink_control *sc)
{
LIST_HEAD(head);
struct nfsd_file *nf;
unsigned long ret;
if (sc)
ret = list_lru_shrink_walk(&nfsd_file_lru, sc,
nfsd_file_lru_cb, &head);
else
ret = list_lru_walk(&nfsd_file_lru,
nfsd_file_lru_cb,
&head, LONG_MAX);
list_for_each_entry(nf, &head, nf_lru) {
spin_lock(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
nfsd_file_do_unhash(nf);
spin_unlock(&nfsd_file_hashtbl[nf->nf_hashval].nfb_lock);
}
nfsd_file_dispose_list_delayed(&head);
return ret;
}
static void
nfsd_file_gc(void)
{
nfsd_file_lru_walk_list(NULL);
}
static void
nfsd_file_gc_worker(struct work_struct *work)
{
nfsd_file_gc();
nfsd_file_schedule_laundrette();
}
static unsigned long
nfsd_file_lru_count(struct shrinker *s, struct shrink_control *sc)
{
return list_lru_count(&nfsd_file_lru);
}
static unsigned long
nfsd_file_lru_scan(struct shrinker *s, struct shrink_control *sc)
{
return nfsd_file_lru_walk_list(sc);
}
static struct shrinker nfsd_file_shrinker = {
.scan_objects = nfsd_file_lru_scan,
.count_objects = nfsd_file_lru_count,
.seeks = 1,
};
static void
__nfsd_file_close_inode(struct inode *inode, unsigned int hashval,
struct list_head *dispose)
{
struct nfsd_file *nf;
struct hlist_node *tmp;
spin_lock(&nfsd_file_hashtbl[hashval].nfb_lock);
hlist_for_each_entry_safe(nf, tmp, &nfsd_file_hashtbl[hashval].nfb_head, nf_node) {
if (inode == nf->nf_inode)
nfsd_file_unhash_and_release_locked(nf, dispose);
}
spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
}
/**
* nfsd_file_close_inode_sync - attempt to forcibly close a nfsd_file
* @inode: inode of the file to attempt to remove
*
* Walk the whole hash bucket, looking for any files that correspond to "inode".
* If any do, then unhash them and put the hashtable reference to them and
* destroy any that had their last reference put. Also ensure that any of the
* fputs also have their final __fput done as well.
*/
void
nfsd_file_close_inode_sync(struct inode *inode)
{
unsigned int hashval = (unsigned int)hash_long(inode->i_ino,
NFSD_FILE_HASH_BITS);
LIST_HEAD(dispose);
__nfsd_file_close_inode(inode, hashval, &dispose);
trace_nfsd_file_close_inode_sync(inode, hashval, !list_empty(&dispose));
nfsd_file_dispose_list_sync(&dispose);
}
/**
* nfsd_file_close_inode_sync - attempt to forcibly close a nfsd_file
* @inode: inode of the file to attempt to remove
*
* Walk the whole hash bucket, looking for any files that correspond to "inode".
* If any do, then unhash them and put the hashtable reference to them and
* destroy any that had their last reference put.
*/
static void
nfsd_file_close_inode(struct inode *inode)
{
unsigned int hashval = (unsigned int)hash_long(inode->i_ino,
NFSD_FILE_HASH_BITS);
LIST_HEAD(dispose);
__nfsd_file_close_inode(inode, hashval, &dispose);
trace_nfsd_file_close_inode(inode, hashval, !list_empty(&dispose));
nfsd_file_dispose_list_delayed(&dispose);
}
/**
* nfsd_file_delayed_close - close unused nfsd_files
* @work: dummy
*
* Walk the LRU list and close any entries that have not been used since
* the last scan.
*
* Note this can deadlock with nfsd_file_cache_purge.
*/
static void
nfsd_file_delayed_close(struct work_struct *work)
{
LIST_HEAD(head);
struct nfsd_fcache_disposal *l = container_of(work,
struct nfsd_fcache_disposal, work);
nfsd_file_list_remove_disposal(&head, l);
nfsd_file_dispose_list(&head);
}
static int
nfsd_file_lease_notifier_call(struct notifier_block *nb, unsigned long arg,
void *data)
{
struct file_lock *fl = data;
/* Only close files for F_SETLEASE leases */
if (fl->fl_flags & FL_LEASE)
nfsd_file_close_inode_sync(file_inode(fl->fl_file));
return 0;
}
static struct notifier_block nfsd_file_lease_notifier = {
.notifier_call = nfsd_file_lease_notifier_call,
};
static int
nfsd_file_fsnotify_handle_event(struct fsnotify_group *group,
struct inode *inode,
u32 mask, const void *data, int data_type,
const struct qstr *file_name, u32 cookie,
struct fsnotify_iter_info *iter_info)
{
trace_nfsd_file_fsnotify_handle_event(inode, mask);
/* Should be no marks on non-regular files */
if (!S_ISREG(inode->i_mode)) {
WARN_ON_ONCE(1);
return 0;
}
/* don't close files if this was not the last link */
if (mask & FS_ATTRIB) {
if (inode->i_nlink)
return 0;
}
nfsd_file_close_inode(inode);
return 0;
}
static const struct fsnotify_ops nfsd_file_fsnotify_ops = {
.handle_event = nfsd_file_fsnotify_handle_event,
.free_mark = nfsd_file_mark_free,
};
int
nfsd_file_cache_init(void)
{
int ret = -ENOMEM;
unsigned int i;
clear_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags);
if (nfsd_file_hashtbl)
return 0;
nfsd_filecache_wq = alloc_workqueue("nfsd_filecache", 0, 0);
if (!nfsd_filecache_wq)
goto out;
nfsd_file_hashtbl = kcalloc(NFSD_FILE_HASH_SIZE,
sizeof(*nfsd_file_hashtbl), GFP_KERNEL);
if (!nfsd_file_hashtbl) {
pr_err("nfsd: unable to allocate nfsd_file_hashtbl\n");
goto out_err;
}
nfsd_file_slab = kmem_cache_create("nfsd_file",
sizeof(struct nfsd_file), 0, 0, NULL);
if (!nfsd_file_slab) {
pr_err("nfsd: unable to create nfsd_file_slab\n");
goto out_err;
}
nfsd_file_mark_slab = kmem_cache_create("nfsd_file_mark",
sizeof(struct nfsd_file_mark), 0, 0, NULL);
if (!nfsd_file_mark_slab) {
pr_err("nfsd: unable to create nfsd_file_mark_slab\n");
goto out_err;
}
ret = list_lru_init(&nfsd_file_lru);
if (ret) {
pr_err("nfsd: failed to init nfsd_file_lru: %d\n", ret);
goto out_err;
}
ret = register_shrinker(&nfsd_file_shrinker);
if (ret) {
pr_err("nfsd: failed to register nfsd_file_shrinker: %d\n", ret);
goto out_lru;
}
ret = lease_register_notifier(&nfsd_file_lease_notifier);
if (ret) {
pr_err("nfsd: unable to register lease notifier: %d\n", ret);
goto out_shrinker;
}
nfsd_file_fsnotify_group = fsnotify_alloc_group(&nfsd_file_fsnotify_ops);
if (IS_ERR(nfsd_file_fsnotify_group)) {
pr_err("nfsd: unable to create fsnotify group: %ld\n",
PTR_ERR(nfsd_file_fsnotify_group));
nfsd_file_fsnotify_group = NULL;
goto out_notifier;
}
for (i = 0; i < NFSD_FILE_HASH_SIZE; i++) {
INIT_HLIST_HEAD(&nfsd_file_hashtbl[i].nfb_head);
spin_lock_init(&nfsd_file_hashtbl[i].nfb_lock);
}
INIT_DELAYED_WORK(&nfsd_filecache_laundrette, nfsd_file_gc_worker);
out:
return ret;
out_notifier:
lease_unregister_notifier(&nfsd_file_lease_notifier);
out_shrinker:
unregister_shrinker(&nfsd_file_shrinker);
out_lru:
list_lru_destroy(&nfsd_file_lru);
out_err:
kmem_cache_destroy(nfsd_file_slab);
nfsd_file_slab = NULL;
kmem_cache_destroy(nfsd_file_mark_slab);
nfsd_file_mark_slab = NULL;
kfree(nfsd_file_hashtbl);
nfsd_file_hashtbl = NULL;
destroy_workqueue(nfsd_filecache_wq);
nfsd_filecache_wq = NULL;
goto out;
}
/*
* Note this can deadlock with nfsd_file_lru_cb.
*/
void
nfsd_file_cache_purge(struct net *net)
{
unsigned int i;
struct nfsd_file *nf;
struct hlist_node *next;
LIST_HEAD(dispose);
bool del;
if (!nfsd_file_hashtbl)
return;
for (i = 0; i < NFSD_FILE_HASH_SIZE; i++) {
struct nfsd_fcache_bucket *nfb = &nfsd_file_hashtbl[i];
spin_lock(&nfb->nfb_lock);
hlist_for_each_entry_safe(nf, next, &nfb->nfb_head, nf_node) {
if (net && nf->nf_net != net)
continue;
del = nfsd_file_unhash_and_release_locked(nf, &dispose);
/*
* Deadlock detected! Something marked this entry as
* unhased, but hasn't removed it from the hash list.
*/
WARN_ON_ONCE(!del);
}
spin_unlock(&nfb->nfb_lock);
nfsd_file_dispose_list(&dispose);
}
}
static struct nfsd_fcache_disposal *
nfsd_alloc_fcache_disposal(struct net *net)
{
struct nfsd_fcache_disposal *l;
l = kmalloc(sizeof(*l), GFP_KERNEL);
if (!l)
return NULL;
INIT_WORK(&l->work, nfsd_file_delayed_close);
l->net = net;
spin_lock_init(&l->lock);
INIT_LIST_HEAD(&l->freeme);
return l;
}
static void
nfsd_free_fcache_disposal(struct nfsd_fcache_disposal *l)
{
rcu_assign_pointer(l->net, NULL);
cancel_work_sync(&l->work);
nfsd_file_dispose_list(&l->freeme);
kfree_rcu(l, rcu);
}
static void
nfsd_add_fcache_disposal(struct nfsd_fcache_disposal *l)
{
spin_lock(&laundrette_lock);
list_add_tail_rcu(&l->list, &laundrettes);
spin_unlock(&laundrette_lock);
}
static void
nfsd_del_fcache_disposal(struct nfsd_fcache_disposal *l)
{
spin_lock(&laundrette_lock);
list_del_rcu(&l->list);
spin_unlock(&laundrette_lock);
}
static int
nfsd_alloc_fcache_disposal_net(struct net *net)
{
struct nfsd_fcache_disposal *l;
l = nfsd_alloc_fcache_disposal(net);
if (!l)
return -ENOMEM;
nfsd_add_fcache_disposal(l);
return 0;
}
static void
nfsd_free_fcache_disposal_net(struct net *net)
{
struct nfsd_fcache_disposal *l;
rcu_read_lock();
list_for_each_entry_rcu(l, &laundrettes, list) {
if (l->net != net)
continue;
nfsd_del_fcache_disposal(l);
rcu_read_unlock();
nfsd_free_fcache_disposal(l);
return;
}
rcu_read_unlock();
}
int
nfsd_file_cache_start_net(struct net *net)
{
return nfsd_alloc_fcache_disposal_net(net);
}
void
nfsd_file_cache_shutdown_net(struct net *net)
{
nfsd_file_cache_purge(net);
nfsd_free_fcache_disposal_net(net);
}
void
nfsd_file_cache_shutdown(void)
{
set_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags);
lease_unregister_notifier(&nfsd_file_lease_notifier);
unregister_shrinker(&nfsd_file_shrinker);
/*
* make sure all callers of nfsd_file_lru_cb are done before
* calling nfsd_file_cache_purge
*/
cancel_delayed_work_sync(&nfsd_filecache_laundrette);
nfsd_file_cache_purge(NULL);
list_lru_destroy(&nfsd_file_lru);
rcu_barrier();
fsnotify_put_group(nfsd_file_fsnotify_group);
nfsd_file_fsnotify_group = NULL;
kmem_cache_destroy(nfsd_file_slab);
nfsd_file_slab = NULL;
fsnotify_wait_marks_destroyed();
kmem_cache_destroy(nfsd_file_mark_slab);
nfsd_file_mark_slab = NULL;
kfree(nfsd_file_hashtbl);
nfsd_file_hashtbl = NULL;
destroy_workqueue(nfsd_filecache_wq);
nfsd_filecache_wq = NULL;
}
static bool
nfsd_match_cred(const struct cred *c1, const struct cred *c2)
{
int i;
if (!uid_eq(c1->fsuid, c2->fsuid))
return false;
if (!gid_eq(c1->fsgid, c2->fsgid))
return false;
if (c1->group_info == NULL || c2->group_info == NULL)
return c1->group_info == c2->group_info;
if (c1->group_info->ngroups != c2->group_info->ngroups)
return false;
for (i = 0; i < c1->group_info->ngroups; i++) {
if (!gid_eq(c1->group_info->gid[i], c2->group_info->gid[i]))
return false;
}
return true;
}
static struct nfsd_file *
nfsd_file_find_locked(struct inode *inode, unsigned int may_flags,
unsigned int hashval, struct net *net)
{
struct nfsd_file *nf;
unsigned char need = may_flags & NFSD_FILE_MAY_MASK;
hlist_for_each_entry_rcu(nf, &nfsd_file_hashtbl[hashval].nfb_head,
nf_node) {
if ((need & nf->nf_may) != need)
continue;
if (nf->nf_inode != inode)
continue;
if (nf->nf_net != net)
continue;
if (!nfsd_match_cred(nf->nf_cred, current_cred()))
continue;
if (nfsd_file_get(nf) != NULL)
return nf;
}
return NULL;
}
/**
* nfsd_file_is_cached - are there any cached open files for this fh?
* @inode: inode of the file to check
*
* Scan the hashtable for open files that match this fh. Returns true if there
* are any, and false if not.
*/
bool
nfsd_file_is_cached(struct inode *inode)
{
bool ret = false;
struct nfsd_file *nf;
unsigned int hashval;
hashval = (unsigned int)hash_long(inode->i_ino, NFSD_FILE_HASH_BITS);
rcu_read_lock();
hlist_for_each_entry_rcu(nf, &nfsd_file_hashtbl[hashval].nfb_head,
nf_node) {
if (inode == nf->nf_inode) {
ret = true;
break;
}
}
rcu_read_unlock();
trace_nfsd_file_is_cached(inode, hashval, (int)ret);
return ret;
}
__be32
nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp,
unsigned int may_flags, struct nfsd_file **pnf)
{
__be32 status;
struct net *net = SVC_NET(rqstp);
struct nfsd_file *nf, *new;
struct inode *inode;
unsigned int hashval;
bool retry = true;
/* FIXME: skip this if fh_dentry is already set? */
status = fh_verify(rqstp, fhp, S_IFREG,
may_flags|NFSD_MAY_OWNER_OVERRIDE);
if (status != nfs_ok)
return status;
inode = d_inode(fhp->fh_dentry);
hashval = (unsigned int)hash_long(inode->i_ino, NFSD_FILE_HASH_BITS);
retry:
rcu_read_lock();
nf = nfsd_file_find_locked(inode, may_flags, hashval, net);
rcu_read_unlock();
if (nf)
goto wait_for_construction;
new = nfsd_file_alloc(inode, may_flags, hashval, net);
if (!new) {
trace_nfsd_file_acquire(rqstp, hashval, inode, may_flags,
NULL, nfserr_jukebox);
return nfserr_jukebox;
}
spin_lock(&nfsd_file_hashtbl[hashval].nfb_lock);
nf = nfsd_file_find_locked(inode, may_flags, hashval, net);
if (nf == NULL)
goto open_file;
spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
nfsd_file_slab_free(&new->nf_rcu);
wait_for_construction:
wait_on_bit(&nf->nf_flags, NFSD_FILE_PENDING, TASK_UNINTERRUPTIBLE);
/* Did construction of this file fail? */
if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags)) {
if (!retry) {
status = nfserr_jukebox;
goto out;
}
retry = false;
nfsd_file_put_noref(nf);
goto retry;
}
this_cpu_inc(nfsd_file_cache_hits);
if (!(may_flags & NFSD_MAY_NOT_BREAK_LEASE)) {
bool write = (may_flags & NFSD_MAY_WRITE);
if (test_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags) ||
(test_bit(NFSD_FILE_BREAK_WRITE, &nf->nf_flags) && write)) {
status = nfserrno(nfsd_open_break_lease(
file_inode(nf->nf_file), may_flags));
if (status == nfs_ok) {
clear_bit(NFSD_FILE_BREAK_READ, &nf->nf_flags);
if (write)
clear_bit(NFSD_FILE_BREAK_WRITE,
&nf->nf_flags);
}
}
}
out:
if (status == nfs_ok) {
*pnf = nf;
} else {
nfsd_file_put(nf);
nf = NULL;
}
trace_nfsd_file_acquire(rqstp, hashval, inode, may_flags, nf, status);
return status;
open_file:
nf = new;
/* Take reference for the hashtable */
refcount_inc(&nf->nf_ref);
__set_bit(NFSD_FILE_HASHED, &nf->nf_flags);
__set_bit(NFSD_FILE_PENDING, &nf->nf_flags);
list_lru_add(&nfsd_file_lru, &nf->nf_lru);
hlist_add_head_rcu(&nf->nf_node, &nfsd_file_hashtbl[hashval].nfb_head);
++nfsd_file_hashtbl[hashval].nfb_count;
nfsd_file_hashtbl[hashval].nfb_maxcount = max(nfsd_file_hashtbl[hashval].nfb_maxcount,
nfsd_file_hashtbl[hashval].nfb_count);
spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
if (atomic_long_inc_return(&nfsd_filecache_count) >= NFSD_FILE_LRU_THRESHOLD)
nfsd_file_gc();
nf->nf_mark = nfsd_file_mark_find_or_create(nf);
if (nf->nf_mark)
status = nfsd_open_verified(rqstp, fhp, S_IFREG,
may_flags, &nf->nf_file);
else
status = nfserr_jukebox;
/*
* If construction failed, or we raced with a call to unlink()
* then unhash.
*/
if (status != nfs_ok || inode->i_nlink == 0) {
bool do_free;
spin_lock(&nfsd_file_hashtbl[hashval].nfb_lock);
do_free = nfsd_file_unhash(nf);
spin_unlock(&nfsd_file_hashtbl[hashval].nfb_lock);
if (do_free)
nfsd_file_put_noref(nf);
}
clear_bit_unlock(NFSD_FILE_PENDING, &nf->nf_flags);
smp_mb__after_atomic();
wake_up_bit(&nf->nf_flags, NFSD_FILE_PENDING);
goto out;
}
/*
* Note that fields may be added, removed or reordered in the future. Programs
* scraping this file for info should test the labels to ensure they're
* getting the correct field.
*/
static int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
{
unsigned int i, count = 0, longest = 0;
unsigned long hits = 0;
/*
* No need for spinlocks here since we're not terribly interested in
* accuracy. We do take the nfsd_mutex simply to ensure that we
* don't end up racing with server shutdown
*/
mutex_lock(&nfsd_mutex);
if (nfsd_file_hashtbl) {
for (i = 0; i < NFSD_FILE_HASH_SIZE; i++) {
count += nfsd_file_hashtbl[i].nfb_count;
longest = max(longest, nfsd_file_hashtbl[i].nfb_count);
}
}
mutex_unlock(&nfsd_mutex);
for_each_possible_cpu(i)
hits += per_cpu(nfsd_file_cache_hits, i);
seq_printf(m, "total entries: %u\n", count);
seq_printf(m, "longest chain: %u\n", longest);
seq_printf(m, "cache hits: %lu\n", hits);
return 0;
}
int nfsd_file_cache_stats_open(struct inode *inode, struct file *file)
{
return single_open(file, nfsd_file_cache_stats_show, NULL);
}