1 files changed, 934 insertions, 0 deletions

diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
new file mode 100644
index 000000000000..ef55e9b1cd4e
--- /dev/null
+++ b/fs/nfsd/filecache.c
@@ -0,0 +1,934 @@
+/*
+ * Open file cache.
+ *
+ * (c) 2015 - Jeff Layton <[email protected]>
+ */
+
+#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_LRU_RESCAN		     (0)
+#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);
+
+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;
+
+enum nfsd_file_laundrette_ctl {
+	NFSD_FILE_LAUNDRETTE_NOFLUSH = 0,
+	NFSD_FILE_LAUNDRETTE_MAY_FLUSH
+};
+
+static void
+nfsd_file_schedule_laundrette(enum nfsd_file_laundrette_ctl ctl)
+{
+	long count = atomic_long_read(&nfsd_filecache_count);
+
+	if (count == 0 || test_bit(NFSD_FILE_SHUTDOWN, &nfsd_file_lru_flags))
+		return;
+
+	/* Be more aggressive about scanning if over the threshold */
+	if (count > NFSD_FILE_LRU_THRESHOLD)
+		mod_delayed_work(system_wq, &nfsd_filecache_laundrette, 0);
+	else
+		schedule_delayed_work(&nfsd_filecache_laundrette, NFSD_LAUNDRETTE_DELAY);
+
+	if (ctl == NFSD_FILE_LAUNDRETTE_NOFLUSH)
+		return;
+
+	/* ...and don't delay flushing if we're out of control */
+	if (count >= NFSD_FILE_LRU_LIMIT)
+		flush_delayed_work(&nfsd_filecache_laundrette);
+}
+
+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 (!atomic_inc_not_zero(&nfm->nfm_ref))
+		return NULL;
+	return nfm;
+}
+
+static void
+nfsd_file_mark_put(struct nfsd_file_mark *nfm)
+{
+	if (atomic_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);
+			fsnotify_put_mark(mark);
+			if (likely(nfm))
+				break;
+		} 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;
+		atomic_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;
+		atomic_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;
+		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 bool
+nfsd_file_in_use(struct nfsd_file *nf)
+{
+	return nfsd_file_check_writeback(nf) ||
+			nfsd_file_check_write_error(nf);
+}
+
+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);
+	if (!list_empty(&nf->nf_lru))
+		list_lru_del(&nfsd_file_lru, &nf->nf_lru);
+	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);
+		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 (atomic_add_unless(&nf->nf_ref, -1, 1))
+		return true;
+
+	list_add(&nf->nf_lru, dispose);
+	return true;
+}
+
+static int
+nfsd_file_put_noref(struct nfsd_file *nf)
+{
+	int count;
+	trace_nfsd_file_put(nf);
+
+	count = atomic_dec_return(&nf->nf_ref);
+	if (!count) {
+		WARN_ON(test_bit(NFSD_FILE_HASHED, &nf->nf_flags));
+		nfsd_file_free(nf);
+	}
+	return count;
+}
+
+void
+nfsd_file_put(struct nfsd_file *nf)
+{
+	bool is_hashed = test_bit(NFSD_FILE_HASHED, &nf->nf_flags) != 0;
+	bool unused = !nfsd_file_in_use(nf);
+
+	set_bit(NFSD_FILE_REFERENCED, &nf->nf_flags);
+	if (nfsd_file_put_noref(nf) == 1 && is_hashed && unused)
+		nfsd_file_schedule_laundrette(NFSD_FILE_LAUNDRETTE_MAY_FLUSH);
+}
+
+struct nfsd_file *
+nfsd_file_get(struct nfsd_file *nf)
+{
+	if (likely(atomic_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 (!atomic_dec_and_test(&nf->nf_ref))
+			continue;
+		if (nfsd_file_free(nf))
+			flush = true;
+	}
+	if (flush)
+		flush_delayed_fput();
+}
+
+/*
+ * 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 (atomic_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_rescan;
+
+	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_rescan:
+	set_bit(NFSD_FILE_LRU_RESCAN, &nfsd_file_lru_flags);
+out_skip:
+	return LRU_SKIP;
+}
+
+static void
+nfsd_file_lru_dispose(struct list_head *head)
+{
+	while(!list_empty(head)) {
+		struct nfsd_file *nf = list_first_entry(head,
+				struct nfsd_file, nf_lru);
+		list_del_init(&nf->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_put_noref(nf);
+	}
+}
+
+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)
+{
+	LIST_HEAD(head);
+	unsigned long ret;
+
+	ret = list_lru_shrink_walk(&nfsd_file_lru, sc, nfsd_file_lru_cb, &head);
+	nfsd_file_lru_dispose(&head);
+	return ret;
+}
+
+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(&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);
+
+	list_lru_walk(&nfsd_file_lru, nfsd_file_lru_cb, &head, LONG_MAX);
+
+	if (test_and_clear_bit(NFSD_FILE_LRU_RESCAN, &nfsd_file_lru_flags))
+		nfsd_file_schedule_laundrette(NFSD_FILE_LAUNDRETTE_NOFLUSH);
+
+	if (!list_empty(&head)) {
+		nfsd_file_lru_dispose(&head);
+		flush_delayed_fput();
+	}
+}
+
+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_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_delayed_close);
+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;
+	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);
+	}
+}
+
+void
+nfsd_file_cache_shutdown(void)
+{
+	LIST_HEAD(dispose);
+
+	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;
+}
+
+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;
+
+	/* 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)) {
+		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 */
+	atomic_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);
+	atomic_long_inc(&nfsd_filecache_count);
+
+	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);
+}