Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3324 insertions, 0 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
new file mode 100644
index 0000000000..9fc5061d51
--- /dev/null
+++ b/fs/nfs/dir.c
@@ -0,0 +1,3324 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/fs/nfs/dir.c
+ *
+ *  Copyright (C) 1992  Rick Sladkey
+ *
+ *  nfs directory handling functions
+ *
+ * 10 Apr 1996	Added silly rename for unlink	--okir
+ * 28 Sep 1996	Improved directory cache --okir
+ * 23 Aug 1997  Claus Heine claus@momo.math.rwth-aachen.de 
+ *              Re-implemented silly rename for unlink, newly implemented
+ *              silly rename for nfs_rename() following the suggestions
+ *              of Olaf Kirch (okir) found in this file.
+ *              Following Linus comments on my original hack, this version
+ *              depends only on the dcache stuff and doesn't touch the inode
+ *              layer (iput() and friends).
+ *  6 Jun 1999	Cache readdir lookups in the page cache. -DaveM
+ */
+
+#include <linux/compat.h>
+#include <linux/module.h>
+#include <linux/time.h>
+#include <linux/errno.h>
+#include <linux/stat.h>
+#include <linux/fcntl.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mm.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_mount.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
+#include <linux/swap.h>
+#include <linux/sched.h>
+#include <linux/kmemleak.h>
+#include <linux/xattr.h>
+#include <linux/hash.h>
+
+#include "delegation.h"
+#include "iostat.h"
+#include "internal.h"
+#include "fscache.h"
+
+#include "nfstrace.h"
+
+/* #define NFS_DEBUG_VERBOSE 1 */
+
+static int nfs_opendir(struct inode *, struct file *);
+static int nfs_closedir(struct inode *, struct file *);
+static int nfs_readdir(struct file *, struct dir_context *);
+static int nfs_fsync_dir(struct file *, loff_t, loff_t, int);
+static loff_t nfs_llseek_dir(struct file *, loff_t, int);
+static void nfs_readdir_clear_array(struct folio *);
+
+const struct file_operations nfs_dir_operations = {
+	.llseek		= nfs_llseek_dir,
+	.read		= generic_read_dir,
+	.iterate_shared	= nfs_readdir,
+	.open		= nfs_opendir,
+	.release	= nfs_closedir,
+	.fsync		= nfs_fsync_dir,
+};
+
+const struct address_space_operations nfs_dir_aops = {
+	.free_folio = nfs_readdir_clear_array,
+};
+
+#define NFS_INIT_DTSIZE PAGE_SIZE
+
+static struct nfs_open_dir_context *
+alloc_nfs_open_dir_context(struct inode *dir)
+{
+	struct nfs_inode *nfsi = NFS_I(dir);
+	struct nfs_open_dir_context *ctx;
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT);
+	if (ctx != NULL) {
+		ctx->attr_gencount = nfsi->attr_gencount;
+		ctx->dtsize = NFS_INIT_DTSIZE;
+		spin_lock(&dir->i_lock);
+		if (list_empty(&nfsi->open_files) &&
+		    (nfsi->cache_validity & NFS_INO_DATA_INVAL_DEFER))
+			nfs_set_cache_invalid(dir,
+					      NFS_INO_INVALID_DATA |
+						      NFS_INO_REVAL_FORCED);
+		list_add_tail_rcu(&ctx->list, &nfsi->open_files);
+		memcpy(ctx->verf, nfsi->cookieverf, sizeof(ctx->verf));
+		spin_unlock(&dir->i_lock);
+		return ctx;
+	}
+	return  ERR_PTR(-ENOMEM);
+}
+
+static void put_nfs_open_dir_context(struct inode *dir, struct nfs_open_dir_context *ctx)
+{
+	spin_lock(&dir->i_lock);
+	list_del_rcu(&ctx->list);
+	spin_unlock(&dir->i_lock);
+	kfree_rcu(ctx, rcu_head);
+}
+
+/*
+ * Open file
+ */
+static int
+nfs_opendir(struct inode *inode, struct file *filp)
+{
+	int res = 0;
+	struct nfs_open_dir_context *ctx;
+
+	dfprintk(FILE, "NFS: open dir(%pD2)\n", filp);
+
+	nfs_inc_stats(inode, NFSIOS_VFSOPEN);
+
+	ctx = alloc_nfs_open_dir_context(inode);
+	if (IS_ERR(ctx)) {
+		res = PTR_ERR(ctx);
+		goto out;
+	}
+	filp->private_data = ctx;
+out:
+	return res;
+}
+
+static int
+nfs_closedir(struct inode *inode, struct file *filp)
+{
+	put_nfs_open_dir_context(file_inode(filp), filp->private_data);
+	return 0;
+}
+
+struct nfs_cache_array_entry {
+	u64 cookie;
+	u64 ino;
+	const char *name;
+	unsigned int name_len;
+	unsigned char d_type;
+};
+
+struct nfs_cache_array {
+	u64 change_attr;
+	u64 last_cookie;
+	unsigned int size;
+	unsigned char folio_full : 1,
+		      folio_is_eof : 1,
+		      cookies_are_ordered : 1;
+	struct nfs_cache_array_entry array[];
+};
+
+struct nfs_readdir_descriptor {
+	struct file	*file;
+	struct folio	*folio;
+	struct dir_context *ctx;
+	pgoff_t		folio_index;
+	pgoff_t		folio_index_max;
+	u64		dir_cookie;
+	u64		last_cookie;
+	loff_t		current_index;
+
+	__be32		verf[NFS_DIR_VERIFIER_SIZE];
+	unsigned long	dir_verifier;
+	unsigned long	timestamp;
+	unsigned long	gencount;
+	unsigned long	attr_gencount;
+	unsigned int	cache_entry_index;
+	unsigned int	buffer_fills;
+	unsigned int	dtsize;
+	bool clear_cache;
+	bool plus;
+	bool eob;
+	bool eof;
+};
+
+static void nfs_set_dtsize(struct nfs_readdir_descriptor *desc, unsigned int sz)
+{
+	struct nfs_server *server = NFS_SERVER(file_inode(desc->file));
+	unsigned int maxsize = server->dtsize;
+
+	if (sz > maxsize)
+		sz = maxsize;
+	if (sz < NFS_MIN_FILE_IO_SIZE)
+		sz = NFS_MIN_FILE_IO_SIZE;
+	desc->dtsize = sz;
+}
+
+static void nfs_shrink_dtsize(struct nfs_readdir_descriptor *desc)
+{
+	nfs_set_dtsize(desc, desc->dtsize >> 1);
+}
+
+static void nfs_grow_dtsize(struct nfs_readdir_descriptor *desc)
+{
+	nfs_set_dtsize(desc, desc->dtsize << 1);
+}
+
+static void nfs_readdir_folio_init_array(struct folio *folio, u64 last_cookie,
+					 u64 change_attr)
+{
+	struct nfs_cache_array *array;
+
+	array = kmap_local_folio(folio, 0);
+	array->change_attr = change_attr;
+	array->last_cookie = last_cookie;
+	array->size = 0;
+	array->folio_full = 0;
+	array->folio_is_eof = 0;
+	array->cookies_are_ordered = 1;
+	kunmap_local(array);
+}
+
+/*
+ * we are freeing strings created by nfs_add_to_readdir_array()
+ */
+static void nfs_readdir_clear_array(struct folio *folio)
+{
+	struct nfs_cache_array *array;
+	unsigned int i;
+
+	array = kmap_local_folio(folio, 0);
+	for (i = 0; i < array->size; i++)
+		kfree(array->array[i].name);
+	array->size = 0;
+	kunmap_local(array);
+}
+
+static void nfs_readdir_folio_reinit_array(struct folio *folio, u64 last_cookie,
+					   u64 change_attr)
+{
+	nfs_readdir_clear_array(folio);
+	nfs_readdir_folio_init_array(folio, last_cookie, change_attr);
+}
+
+static struct folio *
+nfs_readdir_folio_array_alloc(u64 last_cookie, gfp_t gfp_flags)
+{
+	struct folio *folio = folio_alloc(gfp_flags, 0);
+	if (folio)
+		nfs_readdir_folio_init_array(folio, last_cookie, 0);
+	return folio;
+}
+
+static void nfs_readdir_folio_array_free(struct folio *folio)
+{
+	if (folio) {
+		nfs_readdir_clear_array(folio);
+		folio_put(folio);
+	}
+}
+
+static u64 nfs_readdir_array_index_cookie(struct nfs_cache_array *array)
+{
+	return array->size == 0 ? array->last_cookie : array->array[0].cookie;
+}
+
+static void nfs_readdir_array_set_eof(struct nfs_cache_array *array)
+{
+	array->folio_is_eof = 1;
+	array->folio_full = 1;
+}
+
+static bool nfs_readdir_array_is_full(struct nfs_cache_array *array)
+{
+	return array->folio_full;
+}
+
+/*
+ * the caller is responsible for freeing qstr.name
+ * when called by nfs_readdir_add_to_array, the strings will be freed in
+ * nfs_clear_readdir_array()
+ */
+static const char *nfs_readdir_copy_name(const char *name, unsigned int len)
+{
+	const char *ret = kmemdup_nul(name, len, GFP_KERNEL);
+
+	/*
+	 * Avoid a kmemleak false positive. The pointer to the name is stored
+	 * in a page cache page which kmemleak does not scan.
+	 */
+	if (ret != NULL)
+		kmemleak_not_leak(ret);
+	return ret;
+}
+
+static size_t nfs_readdir_array_maxentries(void)
+{
+	return (PAGE_SIZE - sizeof(struct nfs_cache_array)) /
+	       sizeof(struct nfs_cache_array_entry);
+}
+
+/*
+ * Check that the next array entry lies entirely within the page bounds
+ */
+static int nfs_readdir_array_can_expand(struct nfs_cache_array *array)
+{
+	if (array->folio_full)
+		return -ENOSPC;
+	if (array->size == nfs_readdir_array_maxentries()) {
+		array->folio_full = 1;
+		return -ENOSPC;
+	}
+	return 0;
+}
+
+static int nfs_readdir_folio_array_append(struct folio *folio,
+					  const struct nfs_entry *entry,
+					  u64 *cookie)
+{
+	struct nfs_cache_array *array;
+	struct nfs_cache_array_entry *cache_entry;
+	const char *name;
+	int ret = -ENOMEM;
+
+	name = nfs_readdir_copy_name(entry->name, entry->len);
+
+	array = kmap_local_folio(folio, 0);
+	if (!name)
+		goto out;
+	ret = nfs_readdir_array_can_expand(array);
+	if (ret) {
+		kfree(name);
+		goto out;
+	}
+
+	cache_entry = &array->array[array->size];
+	cache_entry->cookie = array->last_cookie;
+	cache_entry->ino = entry->ino;
+	cache_entry->d_type = entry->d_type;
+	cache_entry->name_len = entry->len;
+	cache_entry->name = name;
+	array->last_cookie = entry->cookie;
+	if (array->last_cookie <= cache_entry->cookie)
+		array->cookies_are_ordered = 0;
+	array->size++;
+	if (entry->eof != 0)
+		nfs_readdir_array_set_eof(array);
+out:
+	*cookie = array->last_cookie;
+	kunmap_local(array);
+	return ret;
+}
+
+#define NFS_READDIR_COOKIE_MASK (U32_MAX >> 14)
+/*
+ * Hash algorithm allowing content addressible access to sequences
+ * of directory cookies. Content is addressed by the value of the
+ * cookie index of the first readdir entry in a page.
+ *
+ * We select only the first 18 bits to avoid issues with excessive
+ * memory use for the page cache XArray. 18 bits should allow the caching
+ * of 262144 pages of sequences of readdir entries. Since each page holds
+ * 127 readdir entries for a typical 64-bit system, that works out to a
+ * cache of ~ 33 million entries per directory.
+ */
+static pgoff_t nfs_readdir_folio_cookie_hash(u64 cookie)
+{
+	if (cookie == 0)
+		return 0;
+	return hash_64(cookie, 18);
+}
+
+static bool nfs_readdir_folio_validate(struct folio *folio, u64 last_cookie,
+				       u64 change_attr)
+{
+	struct nfs_cache_array *array = kmap_local_folio(folio, 0);
+	int ret = true;
+
+	if (array->change_attr != change_attr)
+		ret = false;
+	if (nfs_readdir_array_index_cookie(array) != last_cookie)
+		ret = false;
+	kunmap_local(array);
+	return ret;
+}
+
+static void nfs_readdir_folio_unlock_and_put(struct folio *folio)
+{
+	folio_unlock(folio);
+	folio_put(folio);
+}
+
+static void nfs_readdir_folio_init_and_validate(struct folio *folio, u64 cookie,
+						u64 change_attr)
+{
+	if (folio_test_uptodate(folio)) {
+		if (nfs_readdir_folio_validate(folio, cookie, change_attr))
+			return;
+		nfs_readdir_clear_array(folio);
+	}
+	nfs_readdir_folio_init_array(folio, cookie, change_attr);
+	folio_mark_uptodate(folio);
+}
+
+static struct folio *nfs_readdir_folio_get_locked(struct address_space *mapping,
+						  u64 cookie, u64 change_attr)
+{
+	pgoff_t index = nfs_readdir_folio_cookie_hash(cookie);
+	struct folio *folio;
+
+	folio = filemap_grab_folio(mapping, index);
+	if (IS_ERR(folio))
+		return NULL;
+	nfs_readdir_folio_init_and_validate(folio, cookie, change_attr);
+	return folio;
+}
+
+static u64 nfs_readdir_folio_last_cookie(struct folio *folio)
+{
+	struct nfs_cache_array *array;
+	u64 ret;
+
+	array = kmap_local_folio(folio, 0);
+	ret = array->last_cookie;
+	kunmap_local(array);
+	return ret;
+}
+
+static bool nfs_readdir_folio_needs_filling(struct folio *folio)
+{
+	struct nfs_cache_array *array;
+	bool ret;
+
+	array = kmap_local_folio(folio, 0);
+	ret = !nfs_readdir_array_is_full(array);
+	kunmap_local(array);
+	return ret;
+}
+
+static void nfs_readdir_folio_set_eof(struct folio *folio)
+{
+	struct nfs_cache_array *array;
+
+	array = kmap_local_folio(folio, 0);
+	nfs_readdir_array_set_eof(array);
+	kunmap_local(array);
+}
+
+static struct folio *nfs_readdir_folio_get_next(struct address_space *mapping,
+						u64 cookie, u64 change_attr)
+{
+	pgoff_t index = nfs_readdir_folio_cookie_hash(cookie);
+	struct folio *folio;
+
+	folio = __filemap_get_folio(mapping, index,
+			FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
+			mapping_gfp_mask(mapping));
+	if (IS_ERR(folio))
+		return NULL;
+	nfs_readdir_folio_init_and_validate(folio, cookie, change_attr);
+	if (nfs_readdir_folio_last_cookie(folio) != cookie)
+		nfs_readdir_folio_reinit_array(folio, cookie, change_attr);
+	return folio;
+}
+
+static inline
+int is_32bit_api(void)
+{
+#ifdef CONFIG_COMPAT
+	return in_compat_syscall();
+#else
+	return (BITS_PER_LONG == 32);
+#endif
+}
+
+static
+bool nfs_readdir_use_cookie(const struct file *filp)
+{
+	if ((filp->f_mode & FMODE_32BITHASH) ||
+	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))
+		return false;
+	return true;
+}
+
+static void nfs_readdir_seek_next_array(struct nfs_cache_array *array,
+					struct nfs_readdir_descriptor *desc)
+{
+	if (array->folio_full) {
+		desc->last_cookie = array->last_cookie;
+		desc->current_index += array->size;
+		desc->cache_entry_index = 0;
+		desc->folio_index++;
+	} else
+		desc->last_cookie = nfs_readdir_array_index_cookie(array);
+}
+
+static void nfs_readdir_rewind_search(struct nfs_readdir_descriptor *desc)
+{
+	desc->current_index = 0;
+	desc->last_cookie = 0;
+	desc->folio_index = 0;
+}
+
+static int nfs_readdir_search_for_pos(struct nfs_cache_array *array,
+				      struct nfs_readdir_descriptor *desc)
+{
+	loff_t diff = desc->ctx->pos - desc->current_index;
+	unsigned int index;
+
+	if (diff < 0)
+		goto out_eof;
+	if (diff >= array->size) {
+		if (array->folio_is_eof)
+			goto out_eof;
+		nfs_readdir_seek_next_array(array, desc);
+		return -EAGAIN;
+	}
+
+	index = (unsigned int)diff;
+	desc->dir_cookie = array->array[index].cookie;
+	desc->cache_entry_index = index;
+	return 0;
+out_eof:
+	desc->eof = true;
+	return -EBADCOOKIE;
+}
+
+static bool nfs_readdir_array_cookie_in_range(struct nfs_cache_array *array,
+					      u64 cookie)
+{
+	if (!array->cookies_are_ordered)
+		return true;
+	/* Optimisation for monotonically increasing cookies */
+	if (cookie >= array->last_cookie)
+		return false;
+	if (array->size && cookie < array->array[0].cookie)
+		return false;
+	return true;
+}
+
+static int nfs_readdir_search_for_cookie(struct nfs_cache_array *array,
+					 struct nfs_readdir_descriptor *desc)
+{
+	unsigned int i;
+	int status = -EAGAIN;
+
+	if (!nfs_readdir_array_cookie_in_range(array, desc->dir_cookie))
+		goto check_eof;
+
+	for (i = 0; i < array->size; i++) {
+		if (array->array[i].cookie == desc->dir_cookie) {
+			if (nfs_readdir_use_cookie(desc->file))
+				desc->ctx->pos = desc->dir_cookie;
+			else
+				desc->ctx->pos = desc->current_index + i;
+			desc->cache_entry_index = i;
+			return 0;
+		}
+	}
+check_eof:
+	if (array->folio_is_eof) {
+		status = -EBADCOOKIE;
+		if (desc->dir_cookie == array->last_cookie)
+			desc->eof = true;
+	} else
+		nfs_readdir_seek_next_array(array, desc);
+	return status;
+}
+
+static int nfs_readdir_search_array(struct nfs_readdir_descriptor *desc)
+{
+	struct nfs_cache_array *array;
+	int status;
+
+	array = kmap_local_folio(desc->folio, 0);
+
+	if (desc->dir_cookie == 0)
+		status = nfs_readdir_search_for_pos(array, desc);
+	else
+		status = nfs_readdir_search_for_cookie(array, desc);
+
+	kunmap_local(array);
+	return status;
+}
+
+/* Fill a page with xdr information before transferring to the cache page */
+static int nfs_readdir_xdr_filler(struct nfs_readdir_descriptor *desc,
+				  __be32 *verf, u64 cookie,
+				  struct page **pages, size_t bufsize,
+				  __be32 *verf_res)
+{
+	struct inode *inode = file_inode(desc->file);
+	struct nfs_readdir_arg arg = {
+		.dentry = file_dentry(desc->file),
+		.cred = desc->file->f_cred,
+		.verf = verf,
+		.cookie = cookie,
+		.pages = pages,
+		.page_len = bufsize,
+		.plus = desc->plus,
+	};
+	struct nfs_readdir_res res = {
+		.verf = verf_res,
+	};
+	unsigned long	timestamp, gencount;
+	int		error;
+
+ again:
+	timestamp = jiffies;
+	gencount = nfs_inc_attr_generation_counter();
+	desc->dir_verifier = nfs_save_change_attribute(inode);
+	error = NFS_PROTO(inode)->readdir(&arg, &res);
+	if (error < 0) {
+		/* We requested READDIRPLUS, but the server doesn't grok it */
+		if (error == -ENOTSUPP && desc->plus) {
+			NFS_SERVER(inode)->caps &= ~NFS_CAP_READDIRPLUS;
+			desc->plus = arg.plus = false;
+			goto again;
+		}
+		goto error;
+	}
+	desc->timestamp = timestamp;
+	desc->gencount = gencount;
+error:
+	return error;
+}
+
+static int xdr_decode(struct nfs_readdir_descriptor *desc,
+		      struct nfs_entry *entry, struct xdr_stream *xdr)
+{
+	struct inode *inode = file_inode(desc->file);
+	int error;
+
+	error = NFS_PROTO(inode)->decode_dirent(xdr, entry, desc->plus);
+	if (error)
+		return error;
+	entry->fattr->time_start = desc->timestamp;
+	entry->fattr->gencount = desc->gencount;
+	return 0;
+}
+
+/* Match file and dirent using either filehandle or fileid
+ * Note: caller is responsible for checking the fsid
+ */
+static
+int nfs_same_file(struct dentry *dentry, struct nfs_entry *entry)
+{
+	struct inode *inode;
+	struct nfs_inode *nfsi;
+
+	if (d_really_is_negative(dentry))
+		return 0;
+
+	inode = d_inode(dentry);
+	if (is_bad_inode(inode) || NFS_STALE(inode))
+		return 0;
+
+	nfsi = NFS_I(inode);
+	if (entry->fattr->fileid != nfsi->fileid)
+		return 0;
+	if (entry->fh->size && nfs_compare_fh(entry->fh, &nfsi->fh) != 0)
+		return 0;
+	return 1;
+}
+
+#define NFS_READDIR_CACHE_USAGE_THRESHOLD (8UL)
+
+static bool nfs_use_readdirplus(struct inode *dir, struct dir_context *ctx,
+				unsigned int cache_hits,
+				unsigned int cache_misses)
+{
+	if (!nfs_server_capable(dir, NFS_CAP_READDIRPLUS))
+		return false;
+	if (ctx->pos == 0 ||
+	    cache_hits + cache_misses > NFS_READDIR_CACHE_USAGE_THRESHOLD)
+		return true;
+	return false;
+}
+
+/*
+ * This function is called by the getattr code to request the
+ * use of readdirplus to accelerate any future lookups in the same
+ * directory.
+ */
+void nfs_readdir_record_entry_cache_hit(struct inode *dir)
+{
+	struct nfs_inode *nfsi = NFS_I(dir);
+	struct nfs_open_dir_context *ctx;
+
+	if (nfs_server_capable(dir, NFS_CAP_READDIRPLUS) &&
+	    S_ISDIR(dir->i_mode)) {
+		rcu_read_lock();
+		list_for_each_entry_rcu (ctx, &nfsi->open_files, list)
+			atomic_inc(&ctx->cache_hits);
+		rcu_read_unlock();
+	}
+}
+
+/*
+ * This function is mainly for use by nfs_getattr().
+ *
+ * If this is an 'ls -l', we want to force use of readdirplus.
+ */
+void nfs_readdir_record_entry_cache_miss(struct inode *dir)
+{
+	struct nfs_inode *nfsi = NFS_I(dir);
+	struct nfs_open_dir_context *ctx;
+
+	if (nfs_server_capable(dir, NFS_CAP_READDIRPLUS) &&
+	    S_ISDIR(dir->i_mode)) {
+		rcu_read_lock();
+		list_for_each_entry_rcu (ctx, &nfsi->open_files, list)
+			atomic_inc(&ctx->cache_misses);
+		rcu_read_unlock();
+	}
+}
+
+static void nfs_lookup_advise_force_readdirplus(struct inode *dir,
+						unsigned int flags)
+{
+	if (nfs_server_capable(dir, NFS_CAP_CASE_INSENSITIVE))
+		return;
+	if (flags & (LOOKUP_EXCL | LOOKUP_PARENT | LOOKUP_REVAL))
+		return;
+	nfs_readdir_record_entry_cache_miss(dir);
+}
+
+static
+void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry,
+		unsigned long dir_verifier)
+{
+	struct qstr filename = QSTR_INIT(entry->name, entry->len);
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+	struct dentry *dentry;
+	struct dentry *alias;
+	struct inode *inode;
+	int status;
+
+	if (!(entry->fattr->valid & NFS_ATTR_FATTR_FILEID))
+		return;
+	if (!(entry->fattr->valid & NFS_ATTR_FATTR_FSID))
+		return;
+	if (filename.len == 0)
+		return;
+	/* Validate that the name doesn't contain any illegal '\0' */
+	if (strnlen(filename.name, filename.len) != filename.len)
+		return;
+	/* ...or '/' */
+	if (strnchr(filename.name, filename.len, '/'))
+		return;
+	if (filename.name[0] == '.') {
+		if (filename.len == 1)
+			return;
+		if (filename.len == 2 && filename.name[1] == '.')
+			return;
+	}
+	filename.hash = full_name_hash(parent, filename.name, filename.len);
+
+	dentry = d_lookup(parent, &filename);
+again:
+	if (!dentry) {
+		dentry = d_alloc_parallel(parent, &filename, &wq);
+		if (IS_ERR(dentry))
+			return;
+	}
+	if (!d_in_lookup(dentry)) {
+		/* Is there a mountpoint here? If so, just exit */
+		if (!nfs_fsid_equal(&NFS_SB(dentry->d_sb)->fsid,
+					&entry->fattr->fsid))
+			goto out;
+		if (nfs_same_file(dentry, entry)) {
+			if (!entry->fh->size)
+				goto out;
+			nfs_set_verifier(dentry, dir_verifier);
+			status = nfs_refresh_inode(d_inode(dentry), entry->fattr);
+			if (!status)
+				nfs_setsecurity(d_inode(dentry), entry->fattr);
+			trace_nfs_readdir_lookup_revalidate(d_inode(parent),
+							    dentry, 0, status);
+			goto out;
+		} else {
+			trace_nfs_readdir_lookup_revalidate_failed(
+				d_inode(parent), dentry, 0);
+			d_invalidate(dentry);
+			dput(dentry);
+			dentry = NULL;
+			goto again;
+		}
+	}
+	if (!entry->fh->size) {
+		d_lookup_done(dentry);
+		goto out;
+	}
+
+	inode = nfs_fhget(dentry->d_sb, entry->fh, entry->fattr);
+	alias = d_splice_alias(inode, dentry);
+	d_lookup_done(dentry);
+	if (alias) {
+		if (IS_ERR(alias))
+			goto out;
+		dput(dentry);
+		dentry = alias;
+	}
+	nfs_set_verifier(dentry, dir_verifier);
+	trace_nfs_readdir_lookup(d_inode(parent), dentry, 0);
+out:
+	dput(dentry);
+}
+
+static int nfs_readdir_entry_decode(struct nfs_readdir_descriptor *desc,
+				    struct nfs_entry *entry,
+				    struct xdr_stream *stream)
+{
+	int ret;
+
+	if (entry->fattr->label)
+		entry->fattr->label->len = NFS4_MAXLABELLEN;
+	ret = xdr_decode(desc, entry, stream);
+	if (ret || !desc->plus)
+		return ret;
+	nfs_prime_dcache(file_dentry(desc->file), entry, desc->dir_verifier);
+	return 0;
+}
+
+/* Perform conversion from xdr to cache array */
+static int nfs_readdir_folio_filler(struct nfs_readdir_descriptor *desc,
+				    struct nfs_entry *entry,
+				    struct page **xdr_pages, unsigned int buflen,
+				    struct folio **arrays, size_t narrays,
+				    u64 change_attr)
+{
+	struct address_space *mapping = desc->file->f_mapping;
+	struct folio *new, *folio = *arrays;
+	struct xdr_stream stream;
+	struct page *scratch;
+	struct xdr_buf buf;
+	u64 cookie;
+	int status;
+
+	scratch = alloc_page(GFP_KERNEL);
+	if (scratch == NULL)
+		return -ENOMEM;
+
+	xdr_init_decode_pages(&stream, &buf, xdr_pages, buflen);
+	xdr_set_scratch_page(&stream, scratch);
+
+	do {
+		status = nfs_readdir_entry_decode(desc, entry, &stream);
+		if (status != 0)
+			break;
+
+		status = nfs_readdir_folio_array_append(folio, entry, &cookie);
+		if (status != -ENOSPC)
+			continue;
+
+		if (folio->mapping != mapping) {
+			if (!--narrays)
+				break;
+			new = nfs_readdir_folio_array_alloc(cookie, GFP_KERNEL);
+			if (!new)
+				break;
+			arrays++;
+			*arrays = folio = new;
+		} else {
+			new = nfs_readdir_folio_get_next(mapping, cookie,
+							 change_attr);
+			if (!new)
+				break;
+			if (folio != *arrays)
+				nfs_readdir_folio_unlock_and_put(folio);
+			folio = new;
+		}
+		desc->folio_index_max++;
+		status = nfs_readdir_folio_array_append(folio, entry, &cookie);
+	} while (!status && !entry->eof);
+
+	switch (status) {
+	case -EBADCOOKIE:
+		if (!entry->eof)
+			break;
+		nfs_readdir_folio_set_eof(folio);
+		fallthrough;
+	case -EAGAIN:
+		status = 0;
+		break;
+	case -ENOSPC:
+		status = 0;
+		if (!desc->plus)
+			break;
+		while (!nfs_readdir_entry_decode(desc, entry, &stream))
+			;
+	}
+
+	if (folio != *arrays)
+		nfs_readdir_folio_unlock_and_put(folio);
+
+	put_page(scratch);
+	return status;
+}
+
+static void nfs_readdir_free_pages(struct page **pages, size_t npages)
+{
+	while (npages--)
+		put_page(pages[npages]);
+	kfree(pages);
+}
+
+/*
+ * nfs_readdir_alloc_pages() will allocate pages that must be freed with a call
+ * to nfs_readdir_free_pages()
+ */
+static struct page **nfs_readdir_alloc_pages(size_t npages)
+{
+	struct page **pages;
+	size_t i;
+
+	pages = kmalloc_array(npages, sizeof(*pages), GFP_KERNEL);
+	if (!pages)
+		return NULL;
+	for (i = 0; i < npages; i++) {
+		struct page *page = alloc_page(GFP_KERNEL);
+		if (page == NULL)
+			goto out_freepages;
+		pages[i] = page;
+	}
+	return pages;
+
+out_freepages:
+	nfs_readdir_free_pages(pages, i);
+	return NULL;
+}
+
+static int nfs_readdir_xdr_to_array(struct nfs_readdir_descriptor *desc,
+				    __be32 *verf_arg, __be32 *verf_res,
+				    struct folio **arrays, size_t narrays)
+{
+	u64 change_attr;
+	struct page **pages;
+	struct folio *folio = *arrays;
+	struct nfs_entry *entry;
+	size_t array_size;
+	struct inode *inode = file_inode(desc->file);
+	unsigned int dtsize = desc->dtsize;
+	unsigned int pglen;
+	int status = -ENOMEM;
+
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		return -ENOMEM;
+	entry->cookie = nfs_readdir_folio_last_cookie(folio);
+	entry->fh = nfs_alloc_fhandle();
+	entry->fattr = nfs_alloc_fattr_with_label(NFS_SERVER(inode));
+	entry->server = NFS_SERVER(inode);
+	if (entry->fh == NULL || entry->fattr == NULL)
+		goto out;
+
+	array_size = (dtsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	pages = nfs_readdir_alloc_pages(array_size);
+	if (!pages)
+		goto out;
+
+	change_attr = inode_peek_iversion_raw(inode);
+	status = nfs_readdir_xdr_filler(desc, verf_arg, entry->cookie, pages,
+					dtsize, verf_res);
+	if (status < 0)
+		goto free_pages;
+
+	pglen = status;
+	if (pglen != 0)
+		status = nfs_readdir_folio_filler(desc, entry, pages, pglen,
+						  arrays, narrays, change_attr);
+	else
+		nfs_readdir_folio_set_eof(folio);
+	desc->buffer_fills++;
+
+free_pages:
+	nfs_readdir_free_pages(pages, array_size);
+out:
+	nfs_free_fattr(entry->fattr);
+	nfs_free_fhandle(entry->fh);
+	kfree(entry);
+	return status;
+}
+
+static void nfs_readdir_folio_put(struct nfs_readdir_descriptor *desc)
+{
+	folio_put(desc->folio);
+	desc->folio = NULL;
+}
+
+static void
+nfs_readdir_folio_unlock_and_put_cached(struct nfs_readdir_descriptor *desc)
+{
+	folio_unlock(desc->folio);
+	nfs_readdir_folio_put(desc);
+}
+
+static struct folio *
+nfs_readdir_folio_get_cached(struct nfs_readdir_descriptor *desc)
+{
+	struct address_space *mapping = desc->file->f_mapping;
+	u64 change_attr = inode_peek_iversion_raw(mapping->host);
+	u64 cookie = desc->last_cookie;
+	struct folio *folio;
+
+	folio = nfs_readdir_folio_get_locked(mapping, cookie, change_attr);
+	if (!folio)
+		return NULL;
+	if (desc->clear_cache && !nfs_readdir_folio_needs_filling(folio))
+		nfs_readdir_folio_reinit_array(folio, cookie, change_attr);
+	return folio;
+}
+
+/*
+ * Returns 0 if desc->dir_cookie was found on page desc->page_index
+ * and locks the page to prevent removal from the page cache.
+ */
+static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc)
+{
+	struct inode *inode = file_inode(desc->file);
+	struct nfs_inode *nfsi = NFS_I(inode);
+	__be32 verf[NFS_DIR_VERIFIER_SIZE];
+	int res;
+
+	desc->folio = nfs_readdir_folio_get_cached(desc);
+	if (!desc->folio)
+		return -ENOMEM;
+	if (nfs_readdir_folio_needs_filling(desc->folio)) {
+		/* Grow the dtsize if we had to go back for more pages */
+		if (desc->folio_index == desc->folio_index_max)
+			nfs_grow_dtsize(desc);
+		desc->folio_index_max = desc->folio_index;
+		trace_nfs_readdir_cache_fill(desc->file, nfsi->cookieverf,
+					     desc->last_cookie,
+					     desc->folio->index, desc->dtsize);
+		res = nfs_readdir_xdr_to_array(desc, nfsi->cookieverf, verf,
+					       &desc->folio, 1);
+		if (res < 0) {
+			nfs_readdir_folio_unlock_and_put_cached(desc);
+			trace_nfs_readdir_cache_fill_done(inode, res);
+			if (res == -EBADCOOKIE || res == -ENOTSYNC) {
+				invalidate_inode_pages2(desc->file->f_mapping);
+				nfs_readdir_rewind_search(desc);
+				trace_nfs_readdir_invalidate_cache_range(
+					inode, 0, MAX_LFS_FILESIZE);
+				return -EAGAIN;
+			}
+			return res;
+		}
+		/*
+		 * Set the cookie verifier if the page cache was empty
+		 */
+		if (desc->last_cookie == 0 &&
+		    memcmp(nfsi->cookieverf, verf, sizeof(nfsi->cookieverf))) {
+			memcpy(nfsi->cookieverf, verf,
+			       sizeof(nfsi->cookieverf));
+			invalidate_inode_pages2_range(desc->file->f_mapping, 1,
+						      -1);
+			trace_nfs_readdir_invalidate_cache_range(
+				inode, 1, MAX_LFS_FILESIZE);
+		}
+		desc->clear_cache = false;
+	}
+	res = nfs_readdir_search_array(desc);
+	if (res == 0)
+		return 0;
+	nfs_readdir_folio_unlock_and_put_cached(desc);
+	return res;
+}
+
+/* Search for desc->dir_cookie from the beginning of the page cache */
+static int readdir_search_pagecache(struct nfs_readdir_descriptor *desc)
+{
+	int res;
+
+	do {
+		res = find_and_lock_cache_page(desc);
+	} while (res == -EAGAIN);
+	return res;
+}
+
+#define NFS_READDIR_CACHE_MISS_THRESHOLD (16UL)
+
+/*
+ * Once we've found the start of the dirent within a page: fill 'er up...
+ */
+static void nfs_do_filldir(struct nfs_readdir_descriptor *desc,
+			   const __be32 *verf)
+{
+	struct file	*file = desc->file;
+	struct nfs_cache_array *array;
+	unsigned int i;
+	bool first_emit = !desc->dir_cookie;
+
+	array = kmap_local_folio(desc->folio, 0);
+	for (i = desc->cache_entry_index; i < array->size; i++) {
+		struct nfs_cache_array_entry *ent;
+
+		/*
+		 * nfs_readdir_handle_cache_misses return force clear at
+		 * (cache_misses > NFS_READDIR_CACHE_MISS_THRESHOLD) for
+		 * readdir heuristic, NFS_READDIR_CACHE_MISS_THRESHOLD + 1
+		 * entries need be emitted here.
+		 */
+		if (first_emit && i > NFS_READDIR_CACHE_MISS_THRESHOLD + 2) {
+			desc->eob = true;
+			break;
+		}
+
+		ent = &array->array[i];
+		if (!dir_emit(desc->ctx, ent->name, ent->name_len,
+		    nfs_compat_user_ino64(ent->ino), ent->d_type)) {
+			desc->eob = true;
+			break;
+		}
+		memcpy(desc->verf, verf, sizeof(desc->verf));
+		if (i == array->size - 1) {
+			desc->dir_cookie = array->last_cookie;
+			nfs_readdir_seek_next_array(array, desc);
+		} else {
+			desc->dir_cookie = array->array[i + 1].cookie;
+			desc->last_cookie = array->array[0].cookie;
+		}
+		if (nfs_readdir_use_cookie(file))
+			desc->ctx->pos = desc->dir_cookie;
+		else
+			desc->ctx->pos++;
+	}
+	if (array->folio_is_eof)
+		desc->eof = !desc->eob;
+
+	kunmap_local(array);
+	dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %llu\n",
+			(unsigned long long)desc->dir_cookie);
+}
+
+/*
+ * If we cannot find a cookie in our cache, we suspect that this is
+ * because it points to a deleted file, so we ask the server to return
+ * whatever it thinks is the next entry. We then feed this to filldir.
+ * If all goes well, we should then be able to find our way round the
+ * cache on the next call to readdir_search_pagecache();
+ *
+ * NOTE: we cannot add the anonymous page to the pagecache because
+ *	 the data it contains might not be page aligned. Besides,
+ *	 we should already have a complete representation of the
+ *	 directory in the page cache by the time we get here.
+ */
+static int uncached_readdir(struct nfs_readdir_descriptor *desc)
+{
+	struct folio	**arrays;
+	size_t		i, sz = 512;
+	__be32		verf[NFS_DIR_VERIFIER_SIZE];
+	int		status = -ENOMEM;
+
+	dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %llu\n",
+			(unsigned long long)desc->dir_cookie);
+
+	arrays = kcalloc(sz, sizeof(*arrays), GFP_KERNEL);
+	if (!arrays)
+		goto out;
+	arrays[0] = nfs_readdir_folio_array_alloc(desc->dir_cookie, GFP_KERNEL);
+	if (!arrays[0])
+		goto out;
+
+	desc->folio_index = 0;
+	desc->cache_entry_index = 0;
+	desc->last_cookie = desc->dir_cookie;
+	desc->folio_index_max = 0;
+
+	trace_nfs_readdir_uncached(desc->file, desc->verf, desc->last_cookie,
+				   -1, desc->dtsize);
+
+	status = nfs_readdir_xdr_to_array(desc, desc->verf, verf, arrays, sz);
+	if (status < 0) {
+		trace_nfs_readdir_uncached_done(file_inode(desc->file), status);
+		goto out_free;
+	}
+
+	for (i = 0; !desc->eob && i < sz && arrays[i]; i++) {
+		desc->folio = arrays[i];
+		nfs_do_filldir(desc, verf);
+	}
+	desc->folio = NULL;
+
+	/*
+	 * Grow the dtsize if we have to go back for more pages,
+	 * or shrink it if we're reading too many.
+	 */
+	if (!desc->eof) {
+		if (!desc->eob)
+			nfs_grow_dtsize(desc);
+		else if (desc->buffer_fills == 1 &&
+			 i < (desc->folio_index_max >> 1))
+			nfs_shrink_dtsize(desc);
+	}
+out_free:
+	for (i = 0; i < sz && arrays[i]; i++)
+		nfs_readdir_folio_array_free(arrays[i]);
+out:
+	if (!nfs_readdir_use_cookie(desc->file))
+		nfs_readdir_rewind_search(desc);
+	desc->folio_index_max = -1;
+	kfree(arrays);
+	dfprintk(DIRCACHE, "NFS: %s: returns %d\n", __func__, status);
+	return status;
+}
+
+static bool nfs_readdir_handle_cache_misses(struct inode *inode,
+					    struct nfs_readdir_descriptor *desc,
+					    unsigned int cache_misses,
+					    bool force_clear)
+{
+	if (desc->ctx->pos == 0 || !desc->plus)
+		return false;
+	if (cache_misses <= NFS_READDIR_CACHE_MISS_THRESHOLD && !force_clear)
+		return false;
+	trace_nfs_readdir_force_readdirplus(inode);
+	return true;
+}
+
+/* The file offset position represents the dirent entry number.  A
+   last cookie cache takes care of the common case of reading the
+   whole directory.
+ */
+static int nfs_readdir(struct file *file, struct dir_context *ctx)
+{
+	struct dentry	*dentry = file_dentry(file);
+	struct inode	*inode = d_inode(dentry);
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct nfs_open_dir_context *dir_ctx = file->private_data;
+	struct nfs_readdir_descriptor *desc;
+	unsigned int cache_hits, cache_misses;
+	bool force_clear;
+	int res;
+
+	dfprintk(FILE, "NFS: readdir(%pD2) starting at cookie %llu\n",
+			file, (long long)ctx->pos);
+	nfs_inc_stats(inode, NFSIOS_VFSGETDENTS);
+
+	/*
+	 * ctx->pos points to the dirent entry number.
+	 * *desc->dir_cookie has the cookie for the next entry. We have
+	 * to either find the entry with the appropriate number or
+	 * revalidate the cookie.
+	 */
+	nfs_revalidate_mapping(inode, file->f_mapping);
+
+	res = -ENOMEM;
+	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
+	if (!desc)
+		goto out;
+	desc->file = file;
+	desc->ctx = ctx;
+	desc->folio_index_max = -1;
+
+	spin_lock(&file->f_lock);
+	desc->dir_cookie = dir_ctx->dir_cookie;
+	desc->folio_index = dir_ctx->page_index;
+	desc->last_cookie = dir_ctx->last_cookie;
+	desc->attr_gencount = dir_ctx->attr_gencount;
+	desc->eof = dir_ctx->eof;
+	nfs_set_dtsize(desc, dir_ctx->dtsize);
+	memcpy(desc->verf, dir_ctx->verf, sizeof(desc->verf));
+	cache_hits = atomic_xchg(&dir_ctx->cache_hits, 0);
+	cache_misses = atomic_xchg(&dir_ctx->cache_misses, 0);
+	force_clear = dir_ctx->force_clear;
+	spin_unlock(&file->f_lock);
+
+	if (desc->eof) {
+		res = 0;
+		goto out_free;
+	}
+
+	desc->plus = nfs_use_readdirplus(inode, ctx, cache_hits, cache_misses);
+	force_clear = nfs_readdir_handle_cache_misses(inode, desc, cache_misses,
+						      force_clear);
+	desc->clear_cache = force_clear;
+
+	do {
+		res = readdir_search_pagecache(desc);
+
+		if (res == -EBADCOOKIE) {
+			res = 0;
+			/* This means either end of directory */
+			if (desc->dir_cookie && !desc->eof) {
+				/* Or that the server has 'lost' a cookie */
+				res = uncached_readdir(desc);
+				if (res == 0)
+					continue;
+				if (res == -EBADCOOKIE || res == -ENOTSYNC)
+					res = 0;
+			}
+			break;
+		}
+		if (res == -ETOOSMALL && desc->plus) {
+			nfs_zap_caches(inode);
+			desc->plus = false;
+			desc->eof = false;
+			continue;
+		}
+		if (res < 0)
+			break;
+
+		nfs_do_filldir(desc, nfsi->cookieverf);
+		nfs_readdir_folio_unlock_and_put_cached(desc);
+		if (desc->folio_index == desc->folio_index_max)
+			desc->clear_cache = force_clear;
+	} while (!desc->eob && !desc->eof);
+
+	spin_lock(&file->f_lock);
+	dir_ctx->dir_cookie = desc->dir_cookie;
+	dir_ctx->last_cookie = desc->last_cookie;
+	dir_ctx->attr_gencount = desc->attr_gencount;
+	dir_ctx->page_index = desc->folio_index;
+	dir_ctx->force_clear = force_clear;
+	dir_ctx->eof = desc->eof;
+	dir_ctx->dtsize = desc->dtsize;
+	memcpy(dir_ctx->verf, desc->verf, sizeof(dir_ctx->verf));
+	spin_unlock(&file->f_lock);
+out_free:
+	kfree(desc);
+
+out:
+	dfprintk(FILE, "NFS: readdir(%pD2) returns %d\n", file, res);
+	return res;
+}
+
+static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
+{
+	struct nfs_open_dir_context *dir_ctx = filp->private_data;
+
+	dfprintk(FILE, "NFS: llseek dir(%pD2, %lld, %d)\n",
+			filp, offset, whence);
+
+	switch (whence) {
+	default:
+		return -EINVAL;
+	case SEEK_SET:
+		if (offset < 0)
+			return -EINVAL;
+		spin_lock(&filp->f_lock);
+		break;
+	case SEEK_CUR:
+		if (offset == 0)
+			return filp->f_pos;
+		spin_lock(&filp->f_lock);
+		offset += filp->f_pos;
+		if (offset < 0) {
+			spin_unlock(&filp->f_lock);
+			return -EINVAL;
+		}
+	}
+	if (offset != filp->f_pos) {
+		filp->f_pos = offset;
+		dir_ctx->page_index = 0;
+		if (!nfs_readdir_use_cookie(filp)) {
+			dir_ctx->dir_cookie = 0;
+			dir_ctx->last_cookie = 0;
+		} else {
+			dir_ctx->dir_cookie = offset;
+			dir_ctx->last_cookie = offset;
+		}
+		dir_ctx->eof = false;
+	}
+	spin_unlock(&filp->f_lock);
+	return offset;
+}
+
+/*
+ * All directory operations under NFS are synchronous, so fsync()
+ * is a dummy operation.
+ */
+static int nfs_fsync_dir(struct file *filp, loff_t start, loff_t end,
+			 int datasync)
+{
+	dfprintk(FILE, "NFS: fsync dir(%pD2) datasync %d\n", filp, datasync);
+
+	nfs_inc_stats(file_inode(filp), NFSIOS_VFSFSYNC);
+	return 0;
+}
+
+/**
+ * nfs_force_lookup_revalidate - Mark the directory as having changed
+ * @dir: pointer to directory inode
+ *
+ * This forces the revalidation code in nfs_lookup_revalidate() to do a
+ * full lookup on all child dentries of 'dir' whenever a change occurs
+ * on the server that might have invalidated our dcache.
+ *
+ * Note that we reserve bit '0' as a tag to let us know when a dentry
+ * was revalidated while holding a delegation on its inode.
+ *
+ * The caller should be holding dir->i_lock
+ */
+void nfs_force_lookup_revalidate(struct inode *dir)
+{
+	NFS_I(dir)->cache_change_attribute += 2;
+}
+EXPORT_SYMBOL_GPL(nfs_force_lookup_revalidate);
+
+/**
+ * nfs_verify_change_attribute - Detects NFS remote directory changes
+ * @dir: pointer to parent directory inode
+ * @verf: previously saved change attribute
+ *
+ * Return "false" if the verifiers doesn't match the change attribute.
+ * This would usually indicate that the directory contents have changed on
+ * the server, and that any dentries need revalidating.
+ */
+static bool nfs_verify_change_attribute(struct inode *dir, unsigned long verf)
+{
+	return (verf & ~1UL) == nfs_save_change_attribute(dir);
+}
+
+static void nfs_set_verifier_delegated(unsigned long *verf)
+{
+	*verf |= 1UL;
+}
+
+#if IS_ENABLED(CONFIG_NFS_V4)
+static void nfs_unset_verifier_delegated(unsigned long *verf)
+{
+	*verf &= ~1UL;
+}
+#endif /* IS_ENABLED(CONFIG_NFS_V4) */
+
+static bool nfs_test_verifier_delegated(unsigned long verf)
+{
+	return verf & 1;
+}
+
+static bool nfs_verifier_is_delegated(struct dentry *dentry)
+{
+	return nfs_test_verifier_delegated(dentry->d_time);
+}
+
+static void nfs_set_verifier_locked(struct dentry *dentry, unsigned long verf)
+{
+	struct inode *inode = d_inode(dentry);
+	struct inode *dir = d_inode(dentry->d_parent);
+
+	if (!nfs_verify_change_attribute(dir, verf))
+		return;
+	if (inode && NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
+		nfs_set_verifier_delegated(&verf);
+	dentry->d_time = verf;
+}
+
+/**
+ * nfs_set_verifier - save a parent directory verifier in the dentry
+ * @dentry: pointer to dentry
+ * @verf: verifier to save
+ *
+ * Saves the parent directory verifier in @dentry. If the inode has
+ * a delegation, we also tag the dentry as having been revalidated
+ * while holding a delegation so that we know we don't have to
+ * look it up again after a directory change.
+ */
+void nfs_set_verifier(struct dentry *dentry, unsigned long verf)
+{
+
+	spin_lock(&dentry->d_lock);
+	nfs_set_verifier_locked(dentry, verf);
+	spin_unlock(&dentry->d_lock);
+}
+EXPORT_SYMBOL_GPL(nfs_set_verifier);
+
+#if IS_ENABLED(CONFIG_NFS_V4)
+/**
+ * nfs_clear_verifier_delegated - clear the dir verifier delegation tag
+ * @inode: pointer to inode
+ *
+ * Iterates through the dentries in the inode alias list and clears
+ * the tag used to indicate that the dentry has been revalidated
+ * while holding a delegation.
+ * This function is intended for use when the delegation is being
+ * returned or revoked.
+ */
+void nfs_clear_verifier_delegated(struct inode *inode)
+{
+	struct dentry *alias;
+
+	if (!inode)
+		return;
+	spin_lock(&inode->i_lock);
+	hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
+		spin_lock(&alias->d_lock);
+		nfs_unset_verifier_delegated(&alias->d_time);
+		spin_unlock(&alias->d_lock);
+	}
+	spin_unlock(&inode->i_lock);
+}
+EXPORT_SYMBOL_GPL(nfs_clear_verifier_delegated);
+#endif /* IS_ENABLED(CONFIG_NFS_V4) */
+
+static int nfs_dentry_verify_change(struct inode *dir, struct dentry *dentry)
+{
+	if (nfs_server_capable(dir, NFS_CAP_CASE_INSENSITIVE) &&
+	    d_really_is_negative(dentry))
+		return dentry->d_time == inode_peek_iversion_raw(dir);
+	return nfs_verify_change_attribute(dir, dentry->d_time);
+}
+
+/*
+ * A check for whether or not the parent directory has changed.
+ * In the case it has, we assume that the dentries are untrustworthy
+ * and may need to be looked up again.
+ * If rcu_walk prevents us from performing a full check, return 0.
+ */
+static int nfs_check_verifier(struct inode *dir, struct dentry *dentry,
+			      int rcu_walk)
+{
+	if (IS_ROOT(dentry))
+		return 1;
+	if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
+		return 0;
+	if (!nfs_dentry_verify_change(dir, dentry))
+		return 0;
+	/* Revalidate nfsi->cache_change_attribute before we declare a match */
+	if (nfs_mapping_need_revalidate_inode(dir)) {
+		if (rcu_walk)
+			return 0;
+		if (__nfs_revalidate_inode(NFS_SERVER(dir), dir) < 0)
+			return 0;
+	}
+	if (!nfs_dentry_verify_change(dir, dentry))
+		return 0;
+	return 1;
+}
+
+/*
+ * Use intent information to check whether or not we're going to do
+ * an O_EXCL create using this path component.
+ */
+static int nfs_is_exclusive_create(struct inode *dir, unsigned int flags)
+{
+	if (NFS_PROTO(dir)->version == 2)
+		return 0;
+	return flags & LOOKUP_EXCL;
+}
+
+/*
+ * Inode and filehandle revalidation for lookups.
+ *
+ * We force revalidation in the cases where the VFS sets LOOKUP_REVAL,
+ * or if the intent information indicates that we're about to open this
+ * particular file and the "nocto" mount flag is not set.
+ *
+ */
+static
+int nfs_lookup_verify_inode(struct inode *inode, unsigned int flags)
+{
+	struct nfs_server *server = NFS_SERVER(inode);
+	int ret;
+
+	if (IS_AUTOMOUNT(inode))
+		return 0;
+
+	if (flags & LOOKUP_OPEN) {
+		switch (inode->i_mode & S_IFMT) {
+		case S_IFREG:
+			/* A NFSv4 OPEN will revalidate later */
+			if (server->caps & NFS_CAP_ATOMIC_OPEN)
+				goto out;
+			fallthrough;
+		case S_IFDIR:
+			if (server->flags & NFS_MOUNT_NOCTO)
+				break;
+			/* NFS close-to-open cache consistency validation */
+			goto out_force;
+		}
+	}
+
+	/* VFS wants an on-the-wire revalidation */
+	if (flags & LOOKUP_REVAL)
+		goto out_force;
+out:
+	if (inode->i_nlink > 0 ||
+	    (inode->i_nlink == 0 &&
+	     test_bit(NFS_INO_PRESERVE_UNLINKED, &NFS_I(inode)->flags)))
+		return 0;
+	else
+		return -ESTALE;
+out_force:
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+	ret = __nfs_revalidate_inode(server, inode);
+	if (ret != 0)
+		return ret;
+	goto out;
+}
+
+static void nfs_mark_dir_for_revalidate(struct inode *inode)
+{
+	spin_lock(&inode->i_lock);
+	nfs_set_cache_invalid(inode, NFS_INO_INVALID_CHANGE);
+	spin_unlock(&inode->i_lock);
+}
+
+/*
+ * We judge how long we want to trust negative
+ * dentries by looking at the parent inode mtime.
+ *
+ * If parent mtime has changed, we revalidate, else we wait for a
+ * period corresponding to the parent's attribute cache timeout value.
+ *
+ * If LOOKUP_RCU prevents us from performing a full check, return 1
+ * suggesting a reval is needed.
+ *
+ * Note that when creating a new file, or looking up a rename target,
+ * then it shouldn't be necessary to revalidate a negative dentry.
+ */
+static inline
+int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
+		       unsigned int flags)
+{
+	if (flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
+		return 0;
+	if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG)
+		return 1;
+	/* Case insensitive server? Revalidate negative dentries */
+	if (nfs_server_capable(dir, NFS_CAP_CASE_INSENSITIVE))
+		return 1;
+	return !nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU);
+}
+
+static int
+nfs_lookup_revalidate_done(struct inode *dir, struct dentry *dentry,
+			   struct inode *inode, int error)
+{
+	switch (error) {
+	case 1:
+		break;
+	case 0:
+		/*
+		 * We can't d_drop the root of a disconnected tree:
+		 * its d_hash is on the s_anon list and d_drop() would hide
+		 * it from shrink_dcache_for_unmount(), leading to busy
+		 * inodes on unmount and further oopses.
+		 */
+		if (inode && IS_ROOT(dentry))
+			error = 1;
+		break;
+	}
+	trace_nfs_lookup_revalidate_exit(dir, dentry, 0, error);
+	return error;
+}
+
+static int
+nfs_lookup_revalidate_negative(struct inode *dir, struct dentry *dentry,
+			       unsigned int flags)
+{
+	int ret = 1;
+	if (nfs_neg_need_reval(dir, dentry, flags)) {
+		if (flags & LOOKUP_RCU)
+			return -ECHILD;
+		ret = 0;
+	}
+	return nfs_lookup_revalidate_done(dir, dentry, NULL, ret);
+}
+
+static int
+nfs_lookup_revalidate_delegated(struct inode *dir, struct dentry *dentry,
+				struct inode *inode)
+{
+	nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+	return nfs_lookup_revalidate_done(dir, dentry, inode, 1);
+}
+
+static int nfs_lookup_revalidate_dentry(struct inode *dir,
+					struct dentry *dentry,
+					struct inode *inode, unsigned int flags)
+{
+	struct nfs_fh *fhandle;
+	struct nfs_fattr *fattr;
+	unsigned long dir_verifier;
+	int ret;
+
+	trace_nfs_lookup_revalidate_enter(dir, dentry, flags);
+
+	ret = -ENOMEM;
+	fhandle = nfs_alloc_fhandle();
+	fattr = nfs_alloc_fattr_with_label(NFS_SERVER(inode));
+	if (fhandle == NULL || fattr == NULL)
+		goto out;
+
+	dir_verifier = nfs_save_change_attribute(dir);
+	ret = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr);
+	if (ret < 0) {
+		switch (ret) {
+		case -ESTALE:
+		case -ENOENT:
+			ret = 0;
+			break;
+		case -ETIMEDOUT:
+			if (NFS_SERVER(inode)->flags & NFS_MOUNT_SOFTREVAL)
+				ret = 1;
+		}
+		goto out;
+	}
+
+	/* Request help from readdirplus */
+	nfs_lookup_advise_force_readdirplus(dir, flags);
+
+	ret = 0;
+	if (nfs_compare_fh(NFS_FH(inode), fhandle))
+		goto out;
+	if (nfs_refresh_inode(inode, fattr) < 0)
+		goto out;
+
+	nfs_setsecurity(inode, fattr);
+	nfs_set_verifier(dentry, dir_verifier);
+
+	ret = 1;
+out:
+	nfs_free_fattr(fattr);
+	nfs_free_fhandle(fhandle);
+
+	/*
+	 * If the lookup failed despite the dentry change attribute being
+	 * a match, then we should revalidate the directory cache.
+	 */
+	if (!ret && nfs_dentry_verify_change(dir, dentry))
+		nfs_mark_dir_for_revalidate(dir);
+	return nfs_lookup_revalidate_done(dir, dentry, inode, ret);
+}
+
+/*
+ * This is called every time the dcache has a lookup hit,
+ * and we should check whether we can really trust that
+ * lookup.
+ *
+ * NOTE! The hit can be a negative hit too, don't assume
+ * we have an inode!
+ *
+ * If the parent directory is seen to have changed, we throw out the
+ * cached dentry and do a new lookup.
+ */
+static int
+nfs_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
+			 unsigned int flags)
+{
+	struct inode *inode;
+	int error;
+
+	nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE);
+	inode = d_inode(dentry);
+
+	if (!inode)
+		return nfs_lookup_revalidate_negative(dir, dentry, flags);
+
+	if (is_bad_inode(inode)) {
+		dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n",
+				__func__, dentry);
+		goto out_bad;
+	}
+
+	if ((flags & LOOKUP_RENAME_TARGET) && d_count(dentry) < 2 &&
+	    nfs_server_capable(dir, NFS_CAP_CASE_INSENSITIVE))
+		goto out_bad;
+
+	if (nfs_verifier_is_delegated(dentry))
+		return nfs_lookup_revalidate_delegated(dir, dentry, inode);
+
+	/* Force a full look up iff the parent directory has changed */
+	if (!(flags & (LOOKUP_EXCL | LOOKUP_REVAL)) &&
+	    nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) {
+		error = nfs_lookup_verify_inode(inode, flags);
+		if (error) {
+			if (error == -ESTALE)
+				nfs_mark_dir_for_revalidate(dir);
+			goto out_bad;
+		}
+		goto out_valid;
+	}
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	if (NFS_STALE(inode))
+		goto out_bad;
+
+	return nfs_lookup_revalidate_dentry(dir, dentry, inode, flags);
+out_valid:
+	return nfs_lookup_revalidate_done(dir, dentry, inode, 1);
+out_bad:
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+	return nfs_lookup_revalidate_done(dir, dentry, inode, 0);
+}
+
+static int
+__nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags,
+			int (*reval)(struct inode *, struct dentry *, unsigned int))
+{
+	struct dentry *parent;
+	struct inode *dir;
+	int ret;
+
+	if (flags & LOOKUP_RCU) {
+		if (dentry->d_fsdata == NFS_FSDATA_BLOCKED)
+			return -ECHILD;
+		parent = READ_ONCE(dentry->d_parent);
+		dir = d_inode_rcu(parent);
+		if (!dir)
+			return -ECHILD;
+		ret = reval(dir, dentry, flags);
+		if (parent != READ_ONCE(dentry->d_parent))
+			return -ECHILD;
+	} else {
+		/* Wait for unlink to complete */
+		wait_var_event(&dentry->d_fsdata,
+			       dentry->d_fsdata != NFS_FSDATA_BLOCKED);
+		parent = dget_parent(dentry);
+		ret = reval(d_inode(parent), dentry, flags);
+		dput(parent);
+	}
+	return ret;
+}
+
+static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	return __nfs_lookup_revalidate(dentry, flags, nfs_do_lookup_revalidate);
+}
+
+/*
+ * A weaker form of d_revalidate for revalidating just the d_inode(dentry)
+ * when we don't really care about the dentry name. This is called when a
+ * pathwalk ends on a dentry that was not found via a normal lookup in the
+ * parent dir (e.g.: ".", "..", procfs symlinks or mountpoint traversals).
+ *
+ * In this situation, we just want to verify that the inode itself is OK
+ * since the dentry might have changed on the server.
+ */
+static int nfs_weak_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct inode *inode = d_inode(dentry);
+	int error = 0;
+
+	/*
+	 * I believe we can only get a negative dentry here in the case of a
+	 * procfs-style symlink. Just assume it's correct for now, but we may
+	 * eventually need to do something more here.
+	 */
+	if (!inode) {
+		dfprintk(LOOKUPCACHE, "%s: %pd2 has negative inode\n",
+				__func__, dentry);
+		return 1;
+	}
+
+	if (is_bad_inode(inode)) {
+		dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n",
+				__func__, dentry);
+		return 0;
+	}
+
+	error = nfs_lookup_verify_inode(inode, flags);
+	dfprintk(LOOKUPCACHE, "NFS: %s: inode %lu is %s\n",
+			__func__, inode->i_ino, error ? "invalid" : "valid");
+	return !error;
+}
+
+/*
+ * This is called from dput() when d_count is going to 0.
+ */
+static int nfs_dentry_delete(const struct dentry *dentry)
+{
+	dfprintk(VFS, "NFS: dentry_delete(%pd2, %x)\n",
+		dentry, dentry->d_flags);
+
+	/* Unhash any dentry with a stale inode */
+	if (d_really_is_positive(dentry) && NFS_STALE(d_inode(dentry)))
+		return 1;
+
+	if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
+		/* Unhash it, so that ->d_iput() would be called */
+		return 1;
+	}
+	if (!(dentry->d_sb->s_flags & SB_ACTIVE)) {
+		/* Unhash it, so that ancestors of killed async unlink
+		 * files will be cleaned up during umount */
+		return 1;
+	}
+	return 0;
+
+}
+
+/* Ensure that we revalidate inode->i_nlink */
+static void nfs_drop_nlink(struct inode *inode)
+{
+	spin_lock(&inode->i_lock);
+	/* drop the inode if we're reasonably sure this is the last link */
+	if (inode->i_nlink > 0)
+		drop_nlink(inode);
+	NFS_I(inode)->attr_gencount = nfs_inc_attr_generation_counter();
+	nfs_set_cache_invalid(
+		inode, NFS_INO_INVALID_CHANGE | NFS_INO_INVALID_CTIME |
+			       NFS_INO_INVALID_NLINK);
+	spin_unlock(&inode->i_lock);
+}
+
+/*
+ * Called when the dentry loses inode.
+ * We use it to clean up silly-renamed files.
+ */
+static void nfs_dentry_iput(struct dentry *dentry, struct inode *inode)
+{
+	if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
+		nfs_complete_unlink(dentry, inode);
+		nfs_drop_nlink(inode);
+	}
+	iput(inode);
+}
+
+static void nfs_d_release(struct dentry *dentry)
+{
+	/* free cached devname value, if it survived that far */
+	if (unlikely(dentry->d_fsdata)) {
+		if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
+			WARN_ON(1);
+		else
+			kfree(dentry->d_fsdata);
+	}
+}
+
+const struct dentry_operations nfs_dentry_operations = {
+	.d_revalidate	= nfs_lookup_revalidate,
+	.d_weak_revalidate	= nfs_weak_revalidate,
+	.d_delete	= nfs_dentry_delete,
+	.d_iput		= nfs_dentry_iput,
+	.d_automount	= nfs_d_automount,
+	.d_release	= nfs_d_release,
+};
+EXPORT_SYMBOL_GPL(nfs_dentry_operations);
+
+struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)
+{
+	struct dentry *res;
+	struct inode *inode = NULL;
+	struct nfs_fh *fhandle = NULL;
+	struct nfs_fattr *fattr = NULL;
+	unsigned long dir_verifier;
+	int error;
+
+	dfprintk(VFS, "NFS: lookup(%pd2)\n", dentry);
+	nfs_inc_stats(dir, NFSIOS_VFSLOOKUP);
+
+	if (unlikely(dentry->d_name.len > NFS_SERVER(dir)->namelen))
+		return ERR_PTR(-ENAMETOOLONG);
+
+	/*
+	 * If we're doing an exclusive create, optimize away the lookup
+	 * but don't hash the dentry.
+	 */
+	if (nfs_is_exclusive_create(dir, flags) || flags & LOOKUP_RENAME_TARGET)
+		return NULL;
+
+	res = ERR_PTR(-ENOMEM);
+	fhandle = nfs_alloc_fhandle();
+	fattr = nfs_alloc_fattr_with_label(NFS_SERVER(dir));
+	if (fhandle == NULL || fattr == NULL)
+		goto out;
+
+	dir_verifier = nfs_save_change_attribute(dir);
+	trace_nfs_lookup_enter(dir, dentry, flags);
+	error = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr);
+	if (error == -ENOENT) {
+		if (nfs_server_capable(dir, NFS_CAP_CASE_INSENSITIVE))
+			dir_verifier = inode_peek_iversion_raw(dir);
+		goto no_entry;
+	}
+	if (error < 0) {
+		res = ERR_PTR(error);
+		goto out;
+	}
+	inode = nfs_fhget(dentry->d_sb, fhandle, fattr);
+	res = ERR_CAST(inode);
+	if (IS_ERR(res))
+		goto out;
+
+	/* Notify readdir to use READDIRPLUS */
+	nfs_lookup_advise_force_readdirplus(dir, flags);
+
+no_entry:
+	res = d_splice_alias(inode, dentry);
+	if (res != NULL) {
+		if (IS_ERR(res))
+			goto out;
+		dentry = res;
+	}
+	nfs_set_verifier(dentry, dir_verifier);
+out:
+	trace_nfs_lookup_exit(dir, dentry, flags, PTR_ERR_OR_ZERO(res));
+	nfs_free_fattr(fattr);
+	nfs_free_fhandle(fhandle);
+	return res;
+}
+EXPORT_SYMBOL_GPL(nfs_lookup);
+
+void nfs_d_prune_case_insensitive_aliases(struct inode *inode)
+{
+	/* Case insensitive server? Revalidate dentries */
+	if (inode && nfs_server_capable(inode, NFS_CAP_CASE_INSENSITIVE))
+		d_prune_aliases(inode);
+}
+EXPORT_SYMBOL_GPL(nfs_d_prune_case_insensitive_aliases);
+
+#if IS_ENABLED(CONFIG_NFS_V4)
+static int nfs4_lookup_revalidate(struct dentry *, unsigned int);
+
+const struct dentry_operations nfs4_dentry_operations = {
+	.d_revalidate	= nfs4_lookup_revalidate,
+	.d_weak_revalidate	= nfs_weak_revalidate,
+	.d_delete	= nfs_dentry_delete,
+	.d_iput		= nfs_dentry_iput,
+	.d_automount	= nfs_d_automount,
+	.d_release	= nfs_d_release,
+};
+EXPORT_SYMBOL_GPL(nfs4_dentry_operations);
+
+static struct nfs_open_context *create_nfs_open_context(struct dentry *dentry, int open_flags, struct file *filp)
+{
+	return alloc_nfs_open_context(dentry, flags_to_mode(open_flags), filp);
+}
+
+static int do_open(struct inode *inode, struct file *filp)
+{
+	nfs_fscache_open_file(inode, filp);
+	return 0;
+}
+
+static int nfs_finish_open(struct nfs_open_context *ctx,
+			   struct dentry *dentry,
+			   struct file *file, unsigned open_flags)
+{
+	int err;
+
+	err = finish_open(file, dentry, do_open);
+	if (err)
+		goto out;
+	if (S_ISREG(file_inode(file)->i_mode))
+		nfs_file_set_open_context(file, ctx);
+	else
+		err = -EOPENSTALE;
+out:
+	return err;
+}
+
+int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
+		    struct file *file, unsigned open_flags,
+		    umode_t mode)
+{
+	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+	struct nfs_open_context *ctx;
+	struct dentry *res;
+	struct iattr attr = { .ia_valid = ATTR_OPEN };
+	struct inode *inode;
+	unsigned int lookup_flags = 0;
+	unsigned long dir_verifier;
+	bool switched = false;
+	int created = 0;
+	int err;
+
+	/* Expect a negative dentry */
+	BUG_ON(d_inode(dentry));
+
+	dfprintk(VFS, "NFS: atomic_open(%s/%lu), %pd\n",
+			dir->i_sb->s_id, dir->i_ino, dentry);
+
+	err = nfs_check_flags(open_flags);
+	if (err)
+		return err;
+
+	/* NFS only supports OPEN on regular files */
+	if ((open_flags & O_DIRECTORY)) {
+		if (!d_in_lookup(dentry)) {
+			/*
+			 * Hashed negative dentry with O_DIRECTORY: dentry was
+			 * revalidated and is fine, no need to perform lookup
+			 * again
+			 */
+			return -ENOENT;
+		}
+		lookup_flags = LOOKUP_OPEN|LOOKUP_DIRECTORY;
+		goto no_open;
+	}
+
+	if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
+		return -ENAMETOOLONG;
+
+	if (open_flags & O_CREAT) {
+		struct nfs_server *server = NFS_SERVER(dir);
+
+		if (!(server->attr_bitmask[2] & FATTR4_WORD2_MODE_UMASK))
+			mode &= ~current_umask();
+
+		attr.ia_valid |= ATTR_MODE;
+		attr.ia_mode = mode;
+	}
+	if (open_flags & O_TRUNC) {
+		attr.ia_valid |= ATTR_SIZE;
+		attr.ia_size = 0;
+	}
+
+	if (!(open_flags & O_CREAT) && !d_in_lookup(dentry)) {
+		d_drop(dentry);
+		switched = true;
+		dentry = d_alloc_parallel(dentry->d_parent,
+					  &dentry->d_name, &wq);
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
+		if (unlikely(!d_in_lookup(dentry)))
+			return finish_no_open(file, dentry);
+	}
+
+	ctx = create_nfs_open_context(dentry, open_flags, file);
+	err = PTR_ERR(ctx);
+	if (IS_ERR(ctx))
+		goto out;
+
+	trace_nfs_atomic_open_enter(dir, ctx, open_flags);
+	inode = NFS_PROTO(dir)->open_context(dir, ctx, open_flags, &attr, &created);
+	if (created)
+		file->f_mode |= FMODE_CREATED;
+	if (IS_ERR(inode)) {
+		err = PTR_ERR(inode);
+		trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
+		put_nfs_open_context(ctx);
+		d_drop(dentry);
+		switch (err) {
+		case -ENOENT:
+			d_splice_alias(NULL, dentry);
+			if (nfs_server_capable(dir, NFS_CAP_CASE_INSENSITIVE))
+				dir_verifier = inode_peek_iversion_raw(dir);
+			else
+				dir_verifier = nfs_save_change_attribute(dir);
+			nfs_set_verifier(dentry, dir_verifier);
+			break;
+		case -EISDIR:
+		case -ENOTDIR:
+			goto no_open;
+		case -ELOOP:
+			if (!(open_flags & O_NOFOLLOW))
+				goto no_open;
+			break;
+			/* case -EINVAL: */
+		default:
+			break;
+		}
+		goto out;
+	}
+	file->f_mode |= FMODE_CAN_ODIRECT;
+
+	err = nfs_finish_open(ctx, ctx->dentry, file, open_flags);
+	trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
+	put_nfs_open_context(ctx);
+out:
+	if (unlikely(switched)) {
+		d_lookup_done(dentry);
+		dput(dentry);
+	}
+	return err;
+
+no_open:
+	res = nfs_lookup(dir, dentry, lookup_flags);
+	if (!res) {
+		inode = d_inode(dentry);
+		if ((lookup_flags & LOOKUP_DIRECTORY) && inode &&
+		    !(S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)))
+			res = ERR_PTR(-ENOTDIR);
+		else if (inode && S_ISREG(inode->i_mode))
+			res = ERR_PTR(-EOPENSTALE);
+	} else if (!IS_ERR(res)) {
+		inode = d_inode(res);
+		if ((lookup_flags & LOOKUP_DIRECTORY) && inode &&
+		    !(S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))) {
+			dput(res);
+			res = ERR_PTR(-ENOTDIR);
+		} else if (inode && S_ISREG(inode->i_mode)) {
+			dput(res);
+			res = ERR_PTR(-EOPENSTALE);
+		}
+	}
+	if (switched) {
+		d_lookup_done(dentry);
+		if (!res)
+			res = dentry;
+		else
+			dput(dentry);
+	}
+	if (IS_ERR(res))
+		return PTR_ERR(res);
+	return finish_no_open(file, res);
+}
+EXPORT_SYMBOL_GPL(nfs_atomic_open);
+
+static int
+nfs4_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
+			  unsigned int flags)
+{
+	struct inode *inode;
+
+	if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY))
+		goto full_reval;
+	if (d_mountpoint(dentry))
+		goto full_reval;
+
+	inode = d_inode(dentry);
+
+	/* We can't create new files in nfs_open_revalidate(), so we
+	 * optimize away revalidation of negative dentries.
+	 */
+	if (inode == NULL)
+		goto full_reval;
+
+	if (nfs_verifier_is_delegated(dentry))
+		return nfs_lookup_revalidate_delegated(dir, dentry, inode);
+
+	/* NFS only supports OPEN on regular files */
+	if (!S_ISREG(inode->i_mode))
+		goto full_reval;
+
+	/* We cannot do exclusive creation on a positive dentry */
+	if (flags & (LOOKUP_EXCL | LOOKUP_REVAL))
+		goto reval_dentry;
+
+	/* Check if the directory changed */
+	if (!nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU))
+		goto reval_dentry;
+
+	/* Let f_op->open() actually open (and revalidate) the file */
+	return 1;
+reval_dentry:
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+	return nfs_lookup_revalidate_dentry(dir, dentry, inode, flags);
+
+full_reval:
+	return nfs_do_lookup_revalidate(dir, dentry, flags);
+}
+
+static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	return __nfs_lookup_revalidate(dentry, flags,
+			nfs4_do_lookup_revalidate);
+}
+
+#endif /* CONFIG_NFSV4 */
+
+struct dentry *
+nfs_add_or_obtain(struct dentry *dentry, struct nfs_fh *fhandle,
+				struct nfs_fattr *fattr)
+{
+	struct dentry *parent = dget_parent(dentry);
+	struct inode *dir = d_inode(parent);
+	struct inode *inode;
+	struct dentry *d;
+	int error;
+
+	d_drop(dentry);
+
+	if (fhandle->size == 0) {
+		error = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr);
+		if (error)
+			goto out_error;
+	}
+	nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+	if (!(fattr->valid & NFS_ATTR_FATTR)) {
+		struct nfs_server *server = NFS_SB(dentry->d_sb);
+		error = server->nfs_client->rpc_ops->getattr(server, fhandle,
+				fattr, NULL);
+		if (error < 0)
+			goto out_error;
+	}
+	inode = nfs_fhget(dentry->d_sb, fhandle, fattr);
+	d = d_splice_alias(inode, dentry);
+out:
+	dput(parent);
+	return d;
+out_error:
+	d = ERR_PTR(error);
+	goto out;
+}
+EXPORT_SYMBOL_GPL(nfs_add_or_obtain);
+
+/*
+ * Code common to create, mkdir, and mknod.
+ */
+int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
+				struct nfs_fattr *fattr)
+{
+	struct dentry *d;
+
+	d = nfs_add_or_obtain(dentry, fhandle, fattr);
+	if (IS_ERR(d))
+		return PTR_ERR(d);
+
+	/* Callers don't care */
+	dput(d);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nfs_instantiate);
+
+/*
+ * Following a failed create operation, we drop the dentry rather
+ * than retain a negative dentry. This avoids a problem in the event
+ * that the operation succeeded on the server, but an error in the
+ * reply path made it appear to have failed.
+ */
+int nfs_create(struct mnt_idmap *idmap, struct inode *dir,
+	       struct dentry *dentry, umode_t mode, bool excl)
+{
+	struct iattr attr;
+	int open_flags = excl ? O_CREAT | O_EXCL : O_CREAT;
+	int error;
+
+	dfprintk(VFS, "NFS: create(%s/%lu), %pd\n",
+			dir->i_sb->s_id, dir->i_ino, dentry);
+
+	attr.ia_mode = mode;
+	attr.ia_valid = ATTR_MODE;
+
+	trace_nfs_create_enter(dir, dentry, open_flags);
+	error = NFS_PROTO(dir)->create(dir, dentry, &attr, open_flags);
+	trace_nfs_create_exit(dir, dentry, open_flags, error);
+	if (error != 0)
+		goto out_err;
+	return 0;
+out_err:
+	d_drop(dentry);
+	return error;
+}
+EXPORT_SYMBOL_GPL(nfs_create);
+
+/*
+ * See comments for nfs_proc_create regarding failed operations.
+ */
+int
+nfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
+	  struct dentry *dentry, umode_t mode, dev_t rdev)
+{
+	struct iattr attr;
+	int status;
+
+	dfprintk(VFS, "NFS: mknod(%s/%lu), %pd\n",
+			dir->i_sb->s_id, dir->i_ino, dentry);
+
+	attr.ia_mode = mode;
+	attr.ia_valid = ATTR_MODE;
+
+	trace_nfs_mknod_enter(dir, dentry);
+	status = NFS_PROTO(dir)->mknod(dir, dentry, &attr, rdev);
+	trace_nfs_mknod_exit(dir, dentry, status);
+	if (status != 0)
+		goto out_err;
+	return 0;
+out_err:
+	d_drop(dentry);
+	return status;
+}
+EXPORT_SYMBOL_GPL(nfs_mknod);
+
+/*
+ * See comments for nfs_proc_create regarding failed operations.
+ */
+int nfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
+	      struct dentry *dentry, umode_t mode)
+{
+	struct iattr attr;
+	int error;
+
+	dfprintk(VFS, "NFS: mkdir(%s/%lu), %pd\n",
+			dir->i_sb->s_id, dir->i_ino, dentry);
+
+	attr.ia_valid = ATTR_MODE;
+	attr.ia_mode = mode | S_IFDIR;
+
+	trace_nfs_mkdir_enter(dir, dentry);
+	error = NFS_PROTO(dir)->mkdir(dir, dentry, &attr);
+	trace_nfs_mkdir_exit(dir, dentry, error);
+	if (error != 0)
+		goto out_err;
+	return 0;
+out_err:
+	d_drop(dentry);
+	return error;
+}
+EXPORT_SYMBOL_GPL(nfs_mkdir);
+
+static void nfs_dentry_handle_enoent(struct dentry *dentry)
+{
+	if (simple_positive(dentry))
+		d_delete(dentry);
+}
+
+static void nfs_dentry_remove_handle_error(struct inode *dir,
+					   struct dentry *dentry, int error)
+{
+	switch (error) {
+	case -ENOENT:
+		if (d_really_is_positive(dentry))
+			d_delete(dentry);
+		nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+		break;
+	case 0:
+		nfs_d_prune_case_insensitive_aliases(d_inode(dentry));
+		nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+	}
+}
+
+int nfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	int error;
+
+	dfprintk(VFS, "NFS: rmdir(%s/%lu), %pd\n",
+			dir->i_sb->s_id, dir->i_ino, dentry);
+
+	trace_nfs_rmdir_enter(dir, dentry);
+	if (d_really_is_positive(dentry)) {
+		down_write(&NFS_I(d_inode(dentry))->rmdir_sem);
+		error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
+		/* Ensure the VFS deletes this inode */
+		switch (error) {
+		case 0:
+			clear_nlink(d_inode(dentry));
+			break;
+		case -ENOENT:
+			nfs_dentry_handle_enoent(dentry);
+		}
+		up_write(&NFS_I(d_inode(dentry))->rmdir_sem);
+	} else
+		error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
+	nfs_dentry_remove_handle_error(dir, dentry, error);
+	trace_nfs_rmdir_exit(dir, dentry, error);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(nfs_rmdir);
+
+/*
+ * Remove a file after making sure there are no pending writes,
+ * and after checking that the file has only one user. 
+ *
+ * We invalidate the attribute cache and free the inode prior to the operation
+ * to avoid possible races if the server reuses the inode.
+ */
+static int nfs_safe_remove(struct dentry *dentry)
+{
+	struct inode *dir = d_inode(dentry->d_parent);
+	struct inode *inode = d_inode(dentry);
+	int error = -EBUSY;
+		
+	dfprintk(VFS, "NFS: safe_remove(%pd2)\n", dentry);
+
+	/* If the dentry was sillyrenamed, we simply call d_delete() */
+	if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
+		error = 0;
+		goto out;
+	}
+
+	trace_nfs_remove_enter(dir, dentry);
+	if (inode != NULL) {
+		error = NFS_PROTO(dir)->remove(dir, dentry);
+		if (error == 0)
+			nfs_drop_nlink(inode);
+	} else
+		error = NFS_PROTO(dir)->remove(dir, dentry);
+	if (error == -ENOENT)
+		nfs_dentry_handle_enoent(dentry);
+	trace_nfs_remove_exit(dir, dentry, error);
+out:
+	return error;
+}
+
+/*  We do silly rename. In case sillyrename() returns -EBUSY, the inode
+ *  belongs to an active ".nfs..." file and we return -EBUSY.
+ *
+ *  If sillyrename() returns 0, we do nothing, otherwise we unlink.
+ */
+int nfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	int error;
+
+	dfprintk(VFS, "NFS: unlink(%s/%lu, %pd)\n", dir->i_sb->s_id,
+		dir->i_ino, dentry);
+
+	trace_nfs_unlink_enter(dir, dentry);
+	spin_lock(&dentry->d_lock);
+	if (d_count(dentry) > 1 && !test_bit(NFS_INO_PRESERVE_UNLINKED,
+					     &NFS_I(d_inode(dentry))->flags)) {
+		spin_unlock(&dentry->d_lock);
+		/* Start asynchronous writeout of the inode */
+		write_inode_now(d_inode(dentry), 0);
+		error = nfs_sillyrename(dir, dentry);
+		goto out;
+	}
+	/* We must prevent any concurrent open until the unlink
+	 * completes.  ->d_revalidate will wait for ->d_fsdata
+	 * to clear.  We set it here to ensure no lookup succeeds until
+	 * the unlink is complete on the server.
+	 */
+	error = -ETXTBSY;
+	if (WARN_ON(dentry->d_flags & DCACHE_NFSFS_RENAMED) ||
+	    WARN_ON(dentry->d_fsdata == NFS_FSDATA_BLOCKED)) {
+		spin_unlock(&dentry->d_lock);
+		goto out;
+	}
+	/* old devname */
+	kfree(dentry->d_fsdata);
+	dentry->d_fsdata = NFS_FSDATA_BLOCKED;
+
+	spin_unlock(&dentry->d_lock);
+	error = nfs_safe_remove(dentry);
+	nfs_dentry_remove_handle_error(dir, dentry, error);
+	dentry->d_fsdata = NULL;
+	wake_up_var(&dentry->d_fsdata);
+out:
+	trace_nfs_unlink_exit(dir, dentry, error);
+	return error;
+}
+EXPORT_SYMBOL_GPL(nfs_unlink);
+
+/*
+ * To create a symbolic link, most file systems instantiate a new inode,
+ * add a page to it containing the path, then write it out to the disk
+ * using prepare_write/commit_write.
+ *
+ * Unfortunately the NFS client can't create the in-core inode first
+ * because it needs a file handle to create an in-core inode (see
+ * fs/nfs/inode.c:nfs_fhget).  We only have a file handle *after* the
+ * symlink request has completed on the server.
+ *
+ * So instead we allocate a raw page, copy the symname into it, then do
+ * the SYMLINK request with the page as the buffer.  If it succeeds, we
+ * now have a new file handle and can instantiate an in-core NFS inode
+ * and move the raw page into its mapping.
+ */
+int nfs_symlink(struct mnt_idmap *idmap, struct inode *dir,
+		struct dentry *dentry, const char *symname)
+{
+	struct page *page;
+	char *kaddr;
+	struct iattr attr;
+	unsigned int pathlen = strlen(symname);
+	int error;
+
+	dfprintk(VFS, "NFS: symlink(%s/%lu, %pd, %s)\n", dir->i_sb->s_id,
+		dir->i_ino, dentry, symname);
+
+	if (pathlen > PAGE_SIZE)
+		return -ENAMETOOLONG;
+
+	attr.ia_mode = S_IFLNK | S_IRWXUGO;
+	attr.ia_valid = ATTR_MODE;
+
+	page = alloc_page(GFP_USER);
+	if (!page)
+		return -ENOMEM;
+
+	kaddr = page_address(page);
+	memcpy(kaddr, symname, pathlen);
+	if (pathlen < PAGE_SIZE)
+		memset(kaddr + pathlen, 0, PAGE_SIZE - pathlen);
+
+	trace_nfs_symlink_enter(dir, dentry);
+	error = NFS_PROTO(dir)->symlink(dir, dentry, page, pathlen, &attr);
+	trace_nfs_symlink_exit(dir, dentry, error);
+	if (error != 0) {
+		dfprintk(VFS, "NFS: symlink(%s/%lu, %pd, %s) error %d\n",
+			dir->i_sb->s_id, dir->i_ino,
+			dentry, symname, error);
+		d_drop(dentry);
+		__free_page(page);
+		return error;
+	}
+
+	nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+
+	/*
+	 * No big deal if we can't add this page to the page cache here.
+	 * READLINK will get the missing page from the server if needed.
+	 */
+	if (!add_to_page_cache_lru(page, d_inode(dentry)->i_mapping, 0,
+							GFP_KERNEL)) {
+		SetPageUptodate(page);
+		unlock_page(page);
+		/*
+		 * add_to_page_cache_lru() grabs an extra page refcount.
+		 * Drop it here to avoid leaking this page later.
+		 */
+		put_page(page);
+	} else
+		__free_page(page);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nfs_symlink);
+
+int
+nfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = d_inode(old_dentry);
+	int error;
+
+	dfprintk(VFS, "NFS: link(%pd2 -> %pd2)\n",
+		old_dentry, dentry);
+
+	trace_nfs_link_enter(inode, dir, dentry);
+	d_drop(dentry);
+	if (S_ISREG(inode->i_mode))
+		nfs_sync_inode(inode);
+	error = NFS_PROTO(dir)->link(inode, dir, &dentry->d_name);
+	if (error == 0) {
+		nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+		ihold(inode);
+		d_add(dentry, inode);
+	}
+	trace_nfs_link_exit(inode, dir, dentry, error);
+	return error;
+}
+EXPORT_SYMBOL_GPL(nfs_link);
+
+static void
+nfs_unblock_rename(struct rpc_task *task, struct nfs_renamedata *data)
+{
+	struct dentry *new_dentry = data->new_dentry;
+
+	new_dentry->d_fsdata = NULL;
+	wake_up_var(&new_dentry->d_fsdata);
+}
+
+/*
+ * RENAME
+ * FIXME: Some nfsds, like the Linux user space nfsd, may generate a
+ * different file handle for the same inode after a rename (e.g. when
+ * moving to a different directory). A fail-safe method to do so would
+ * be to look up old_dir/old_name, create a link to new_dir/new_name and
+ * rename the old file using the sillyrename stuff. This way, the original
+ * file in old_dir will go away when the last process iput()s the inode.
+ *
+ * FIXED.
+ * 
+ * It actually works quite well. One needs to have the possibility for
+ * at least one ".nfs..." file in each directory the file ever gets
+ * moved or linked to which happens automagically with the new
+ * implementation that only depends on the dcache stuff instead of
+ * using the inode layer
+ *
+ * Unfortunately, things are a little more complicated than indicated
+ * above. For a cross-directory move, we want to make sure we can get
+ * rid of the old inode after the operation.  This means there must be
+ * no pending writes (if it's a file), and the use count must be 1.
+ * If these conditions are met, we can drop the dentries before doing
+ * the rename.
+ */
+int nfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
+	       struct dentry *old_dentry, struct inode *new_dir,
+	       struct dentry *new_dentry, unsigned int flags)
+{
+	struct inode *old_inode = d_inode(old_dentry);
+	struct inode *new_inode = d_inode(new_dentry);
+	struct dentry *dentry = NULL;
+	struct rpc_task *task;
+	bool must_unblock = false;
+	int error = -EBUSY;
+
+	if (flags)
+		return -EINVAL;
+
+	dfprintk(VFS, "NFS: rename(%pd2 -> %pd2, ct=%d)\n",
+		 old_dentry, new_dentry,
+		 d_count(new_dentry));
+
+	trace_nfs_rename_enter(old_dir, old_dentry, new_dir, new_dentry);
+	/*
+	 * For non-directories, check whether the target is busy and if so,
+	 * make a copy of the dentry and then do a silly-rename. If the
+	 * silly-rename succeeds, the copied dentry is hashed and becomes
+	 * the new target.
+	 */
+	if (new_inode && !S_ISDIR(new_inode->i_mode)) {
+		/* We must prevent any concurrent open until the unlink
+		 * completes.  ->d_revalidate will wait for ->d_fsdata
+		 * to clear.  We set it here to ensure no lookup succeeds until
+		 * the unlink is complete on the server.
+		 */
+		error = -ETXTBSY;
+		if (WARN_ON(new_dentry->d_flags & DCACHE_NFSFS_RENAMED) ||
+		    WARN_ON(new_dentry->d_fsdata == NFS_FSDATA_BLOCKED))
+			goto out;
+		if (new_dentry->d_fsdata) {
+			/* old devname */
+			kfree(new_dentry->d_fsdata);
+			new_dentry->d_fsdata = NULL;
+		}
+
+		spin_lock(&new_dentry->d_lock);
+		if (d_count(new_dentry) > 2) {
+			int err;
+
+			spin_unlock(&new_dentry->d_lock);
+
+			/* copy the target dentry's name */
+			dentry = d_alloc(new_dentry->d_parent,
+					 &new_dentry->d_name);
+			if (!dentry)
+				goto out;
+
+			/* silly-rename the existing target ... */
+			err = nfs_sillyrename(new_dir, new_dentry);
+			if (err)
+				goto out;
+
+			new_dentry = dentry;
+			new_inode = NULL;
+		} else {
+			new_dentry->d_fsdata = NFS_FSDATA_BLOCKED;
+			must_unblock = true;
+			spin_unlock(&new_dentry->d_lock);
+		}
+
+	}
+
+	if (S_ISREG(old_inode->i_mode))
+		nfs_sync_inode(old_inode);
+	task = nfs_async_rename(old_dir, new_dir, old_dentry, new_dentry,
+				must_unblock ? nfs_unblock_rename : NULL);
+	if (IS_ERR(task)) {
+		error = PTR_ERR(task);
+		goto out;
+	}
+
+	error = rpc_wait_for_completion_task(task);
+	if (error != 0) {
+		((struct nfs_renamedata *)task->tk_calldata)->cancelled = 1;
+		/* Paired with the atomic_dec_and_test() barrier in rpc_do_put_task() */
+		smp_wmb();
+	} else
+		error = task->tk_status;
+	rpc_put_task(task);
+	/* Ensure the inode attributes are revalidated */
+	if (error == 0) {
+		spin_lock(&old_inode->i_lock);
+		NFS_I(old_inode)->attr_gencount = nfs_inc_attr_generation_counter();
+		nfs_set_cache_invalid(old_inode, NFS_INO_INVALID_CHANGE |
+							 NFS_INO_INVALID_CTIME |
+							 NFS_INO_REVAL_FORCED);
+		spin_unlock(&old_inode->i_lock);
+	}
+out:
+	trace_nfs_rename_exit(old_dir, old_dentry,
+			new_dir, new_dentry, error);
+	if (!error) {
+		if (new_inode != NULL)
+			nfs_drop_nlink(new_inode);
+		/*
+		 * The d_move() should be here instead of in an async RPC completion
+		 * handler because we need the proper locks to move the dentry.  If
+		 * we're interrupted by a signal, the async RPC completion handler
+		 * should mark the directories for revalidation.
+		 */
+		d_move(old_dentry, new_dentry);
+		nfs_set_verifier(old_dentry,
+					nfs_save_change_attribute(new_dir));
+	} else if (error == -ENOENT)
+		nfs_dentry_handle_enoent(old_dentry);
+
+	/* new dentry created? */
+	if (dentry)
+		dput(dentry);
+	return error;
+}
+EXPORT_SYMBOL_GPL(nfs_rename);
+
+static DEFINE_SPINLOCK(nfs_access_lru_lock);
+static LIST_HEAD(nfs_access_lru_list);
+static atomic_long_t nfs_access_nr_entries;
+
+static unsigned long nfs_access_max_cachesize = 4*1024*1024;
+module_param(nfs_access_max_cachesize, ulong, 0644);
+MODULE_PARM_DESC(nfs_access_max_cachesize, "NFS access maximum total cache length");
+
+static void nfs_access_free_entry(struct nfs_access_entry *entry)
+{
+	put_group_info(entry->group_info);
+	kfree_rcu(entry, rcu_head);
+	smp_mb__before_atomic();
+	atomic_long_dec(&nfs_access_nr_entries);
+	smp_mb__after_atomic();
+}
+
+static void nfs_access_free_list(struct list_head *head)
+{
+	struct nfs_access_entry *cache;
+
+	while (!list_empty(head)) {
+		cache = list_entry(head->next, struct nfs_access_entry, lru);
+		list_del(&cache->lru);
+		nfs_access_free_entry(cache);
+	}
+}
+
+static unsigned long
+nfs_do_access_cache_scan(unsigned int nr_to_scan)
+{
+	LIST_HEAD(head);
+	struct nfs_inode *nfsi, *next;
+	struct nfs_access_entry *cache;
+	long freed = 0;
+
+	spin_lock(&nfs_access_lru_lock);
+	list_for_each_entry_safe(nfsi, next, &nfs_access_lru_list, access_cache_inode_lru) {
+		struct inode *inode;
+
+		if (nr_to_scan-- == 0)
+			break;
+		inode = &nfsi->vfs_inode;
+		spin_lock(&inode->i_lock);
+		if (list_empty(&nfsi->access_cache_entry_lru))
+			goto remove_lru_entry;
+		cache = list_entry(nfsi->access_cache_entry_lru.next,
+				struct nfs_access_entry, lru);
+		list_move(&cache->lru, &head);
+		rb_erase(&cache->rb_node, &nfsi->access_cache);
+		freed++;
+		if (!list_empty(&nfsi->access_cache_entry_lru))
+			list_move_tail(&nfsi->access_cache_inode_lru,
+					&nfs_access_lru_list);
+		else {
+remove_lru_entry:
+			list_del_init(&nfsi->access_cache_inode_lru);
+			smp_mb__before_atomic();
+			clear_bit(NFS_INO_ACL_LRU_SET, &nfsi->flags);
+			smp_mb__after_atomic();
+		}
+		spin_unlock(&inode->i_lock);
+	}
+	spin_unlock(&nfs_access_lru_lock);
+	nfs_access_free_list(&head);
+	return freed;
+}
+
+unsigned long
+nfs_access_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
+{
+	int nr_to_scan = sc->nr_to_scan;
+	gfp_t gfp_mask = sc->gfp_mask;
+
+	if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
+		return SHRINK_STOP;
+	return nfs_do_access_cache_scan(nr_to_scan);
+}
+
+
+unsigned long
+nfs_access_cache_count(struct shrinker *shrink, struct shrink_control *sc)
+{
+	return vfs_pressure_ratio(atomic_long_read(&nfs_access_nr_entries));
+}
+
+static void
+nfs_access_cache_enforce_limit(void)
+{
+	long nr_entries = atomic_long_read(&nfs_access_nr_entries);
+	unsigned long diff;
+	unsigned int nr_to_scan;
+
+	if (nr_entries < 0 || nr_entries <= nfs_access_max_cachesize)
+		return;
+	nr_to_scan = 100;
+	diff = nr_entries - nfs_access_max_cachesize;
+	if (diff < nr_to_scan)
+		nr_to_scan = diff;
+	nfs_do_access_cache_scan(nr_to_scan);
+}
+
+static void __nfs_access_zap_cache(struct nfs_inode *nfsi, struct list_head *head)
+{
+	struct rb_root *root_node = &nfsi->access_cache;
+	struct rb_node *n;
+	struct nfs_access_entry *entry;
+
+	/* Unhook entries from the cache */
+	while ((n = rb_first(root_node)) != NULL) {
+		entry = rb_entry(n, struct nfs_access_entry, rb_node);
+		rb_erase(n, root_node);
+		list_move(&entry->lru, head);
+	}
+	nfsi->cache_validity &= ~NFS_INO_INVALID_ACCESS;
+}
+
+void nfs_access_zap_cache(struct inode *inode)
+{
+	LIST_HEAD(head);
+
+	if (test_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags) == 0)
+		return;
+	/* Remove from global LRU init */
+	spin_lock(&nfs_access_lru_lock);
+	if (test_and_clear_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags))
+		list_del_init(&NFS_I(inode)->access_cache_inode_lru);
+
+	spin_lock(&inode->i_lock);
+	__nfs_access_zap_cache(NFS_I(inode), &head);
+	spin_unlock(&inode->i_lock);
+	spin_unlock(&nfs_access_lru_lock);
+	nfs_access_free_list(&head);
+}
+EXPORT_SYMBOL_GPL(nfs_access_zap_cache);
+
+static int access_cmp(const struct cred *a, const struct nfs_access_entry *b)
+{
+	struct group_info *ga, *gb;
+	int g;
+
+	if (uid_lt(a->fsuid, b->fsuid))
+		return -1;
+	if (uid_gt(a->fsuid, b->fsuid))
+		return 1;
+
+	if (gid_lt(a->fsgid, b->fsgid))
+		return -1;
+	if (gid_gt(a->fsgid, b->fsgid))
+		return 1;
+
+	ga = a->group_info;
+	gb = b->group_info;
+	if (ga == gb)
+		return 0;
+	if (ga == NULL)
+		return -1;
+	if (gb == NULL)
+		return 1;
+	if (ga->ngroups < gb->ngroups)
+		return -1;
+	if (ga->ngroups > gb->ngroups)
+		return 1;
+
+	for (g = 0; g < ga->ngroups; g++) {
+		if (gid_lt(ga->gid[g], gb->gid[g]))
+			return -1;
+		if (gid_gt(ga->gid[g], gb->gid[g]))
+			return 1;
+	}
+	return 0;
+}
+
+static struct nfs_access_entry *nfs_access_search_rbtree(struct inode *inode, const struct cred *cred)
+{
+	struct rb_node *n = NFS_I(inode)->access_cache.rb_node;
+
+	while (n != NULL) {
+		struct nfs_access_entry *entry =
+			rb_entry(n, struct nfs_access_entry, rb_node);
+		int cmp = access_cmp(cred, entry);
+
+		if (cmp < 0)
+			n = n->rb_left;
+		else if (cmp > 0)
+			n = n->rb_right;
+		else
+			return entry;
+	}
+	return NULL;
+}
+
+static u64 nfs_access_login_time(const struct task_struct *task,
+				 const struct cred *cred)
+{
+	const struct task_struct *parent;
+	const struct cred *pcred;
+	u64 ret;
+
+	rcu_read_lock();
+	for (;;) {
+		parent = rcu_dereference(task->real_parent);
+		pcred = __task_cred(parent);
+		if (parent == task || cred_fscmp(pcred, cred) != 0)
+			break;
+		task = parent;
+	}
+	ret = task->start_time;
+	rcu_read_unlock();
+	return ret;
+}
+
+static int nfs_access_get_cached_locked(struct inode *inode, const struct cred *cred, u32 *mask, bool may_block)
+{
+	struct nfs_inode *nfsi = NFS_I(inode);
+	u64 login_time = nfs_access_login_time(current, cred);
+	struct nfs_access_entry *cache;
+	bool retry = true;
+	int err;
+
+	spin_lock(&inode->i_lock);
+	for(;;) {
+		if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
+			goto out_zap;
+		cache = nfs_access_search_rbtree(inode, cred);
+		err = -ENOENT;
+		if (cache == NULL)
+			goto out;
+		/* Found an entry, is our attribute cache valid? */
+		if (!nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
+			break;
+		if (!retry)
+			break;
+		err = -ECHILD;
+		if (!may_block)
+			goto out;
+		spin_unlock(&inode->i_lock);
+		err = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
+		if (err)
+			return err;
+		spin_lock(&inode->i_lock);
+		retry = false;
+	}
+	err = -ENOENT;
+	if ((s64)(login_time - cache->timestamp) > 0)
+		goto out;
+	*mask = cache->mask;
+	list_move_tail(&cache->lru, &nfsi->access_cache_entry_lru);
+	err = 0;
+out:
+	spin_unlock(&inode->i_lock);
+	return err;
+out_zap:
+	spin_unlock(&inode->i_lock);
+	nfs_access_zap_cache(inode);
+	return -ENOENT;
+}
+
+static int nfs_access_get_cached_rcu(struct inode *inode, const struct cred *cred, u32 *mask)
+{
+	/* Only check the most recently returned cache entry,
+	 * but do it without locking.
+	 */
+	struct nfs_inode *nfsi = NFS_I(inode);
+	u64 login_time = nfs_access_login_time(current, cred);
+	struct nfs_access_entry *cache;
+	int err = -ECHILD;
+	struct list_head *lh;
+
+	rcu_read_lock();
+	if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
+		goto out;
+	lh = rcu_dereference(list_tail_rcu(&nfsi->access_cache_entry_lru));
+	cache = list_entry(lh, struct nfs_access_entry, lru);
+	if (lh == &nfsi->access_cache_entry_lru ||
+	    access_cmp(cred, cache) != 0)
+		cache = NULL;
+	if (cache == NULL)
+		goto out;
+	if ((s64)(login_time - cache->timestamp) > 0)
+		goto out;
+	if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_ACCESS))
+		goto out;
+	*mask = cache->mask;
+	err = 0;
+out:
+	rcu_read_unlock();
+	return err;
+}
+
+int nfs_access_get_cached(struct inode *inode, const struct cred *cred,
+			  u32 *mask, bool may_block)
+{
+	int status;
+
+	status = nfs_access_get_cached_rcu(inode, cred, mask);
+	if (status != 0)
+		status = nfs_access_get_cached_locked(inode, cred, mask,
+		    may_block);
+
+	return status;
+}
+EXPORT_SYMBOL_GPL(nfs_access_get_cached);
+
+static void nfs_access_add_rbtree(struct inode *inode,
+				  struct nfs_access_entry *set,
+				  const struct cred *cred)
+{
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct rb_root *root_node = &nfsi->access_cache;
+	struct rb_node **p = &root_node->rb_node;
+	struct rb_node *parent = NULL;
+	struct nfs_access_entry *entry;
+	int cmp;
+
+	spin_lock(&inode->i_lock);
+	while (*p != NULL) {
+		parent = *p;
+		entry = rb_entry(parent, struct nfs_access_entry, rb_node);
+		cmp = access_cmp(cred, entry);
+
+		if (cmp < 0)
+			p = &parent->rb_left;
+		else if (cmp > 0)
+			p = &parent->rb_right;
+		else
+			goto found;
+	}
+	rb_link_node(&set->rb_node, parent, p);
+	rb_insert_color(&set->rb_node, root_node);
+	list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
+	spin_unlock(&inode->i_lock);
+	return;
+found:
+	rb_replace_node(parent, &set->rb_node, root_node);
+	list_add_tail(&set->lru, &nfsi->access_cache_entry_lru);
+	list_del(&entry->lru);
+	spin_unlock(&inode->i_lock);
+	nfs_access_free_entry(entry);
+}
+
+void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set,
+			  const struct cred *cred)
+{
+	struct nfs_access_entry *cache = kmalloc(sizeof(*cache), GFP_KERNEL);
+	if (cache == NULL)
+		return;
+	RB_CLEAR_NODE(&cache->rb_node);
+	cache->fsuid = cred->fsuid;
+	cache->fsgid = cred->fsgid;
+	cache->group_info = get_group_info(cred->group_info);
+	cache->mask = set->mask;
+	cache->timestamp = ktime_get_ns();
+
+	/* The above field assignments must be visible
+	 * before this item appears on the lru.  We cannot easily
+	 * use rcu_assign_pointer, so just force the memory barrier.
+	 */
+	smp_wmb();
+	nfs_access_add_rbtree(inode, cache, cred);
+
+	/* Update accounting */
+	smp_mb__before_atomic();
+	atomic_long_inc(&nfs_access_nr_entries);
+	smp_mb__after_atomic();
+
+	/* Add inode to global LRU list */
+	if (!test_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags)) {
+		spin_lock(&nfs_access_lru_lock);
+		if (!test_and_set_bit(NFS_INO_ACL_LRU_SET, &NFS_I(inode)->flags))
+			list_add_tail(&NFS_I(inode)->access_cache_inode_lru,
+					&nfs_access_lru_list);
+		spin_unlock(&nfs_access_lru_lock);
+	}
+	nfs_access_cache_enforce_limit();
+}
+EXPORT_SYMBOL_GPL(nfs_access_add_cache);
+
+#define NFS_MAY_READ (NFS_ACCESS_READ)
+#define NFS_MAY_WRITE (NFS_ACCESS_MODIFY | \
+		NFS_ACCESS_EXTEND | \
+		NFS_ACCESS_DELETE)
+#define NFS_FILE_MAY_WRITE (NFS_ACCESS_MODIFY | \
+		NFS_ACCESS_EXTEND)
+#define NFS_DIR_MAY_WRITE NFS_MAY_WRITE
+#define NFS_MAY_LOOKUP (NFS_ACCESS_LOOKUP)
+#define NFS_MAY_EXECUTE (NFS_ACCESS_EXECUTE)
+static int
+nfs_access_calc_mask(u32 access_result, umode_t umode)
+{
+	int mask = 0;
+
+	if (access_result & NFS_MAY_READ)
+		mask |= MAY_READ;
+	if (S_ISDIR(umode)) {
+		if ((access_result & NFS_DIR_MAY_WRITE) == NFS_DIR_MAY_WRITE)
+			mask |= MAY_WRITE;
+		if ((access_result & NFS_MAY_LOOKUP) == NFS_MAY_LOOKUP)
+			mask |= MAY_EXEC;
+	} else if (S_ISREG(umode)) {
+		if ((access_result & NFS_FILE_MAY_WRITE) == NFS_FILE_MAY_WRITE)
+			mask |= MAY_WRITE;
+		if ((access_result & NFS_MAY_EXECUTE) == NFS_MAY_EXECUTE)
+			mask |= MAY_EXEC;
+	} else if (access_result & NFS_MAY_WRITE)
+			mask |= MAY_WRITE;
+	return mask;
+}
+
+void nfs_access_set_mask(struct nfs_access_entry *entry, u32 access_result)
+{
+	entry->mask = access_result;
+}
+EXPORT_SYMBOL_GPL(nfs_access_set_mask);
+
+static int nfs_do_access(struct inode *inode, const struct cred *cred, int mask)
+{
+	struct nfs_access_entry cache;
+	bool may_block = (mask & MAY_NOT_BLOCK) == 0;
+	int cache_mask = -1;
+	int status;
+
+	trace_nfs_access_enter(inode);
+
+	status = nfs_access_get_cached(inode, cred, &cache.mask, may_block);
+	if (status == 0)
+		goto out_cached;
+
+	status = -ECHILD;
+	if (!may_block)
+		goto out;
+
+	/*
+	 * Determine which access bits we want to ask for...
+	 */
+	cache.mask = NFS_ACCESS_READ | NFS_ACCESS_MODIFY | NFS_ACCESS_EXTEND |
+		     nfs_access_xattr_mask(NFS_SERVER(inode));
+	if (S_ISDIR(inode->i_mode))
+		cache.mask |= NFS_ACCESS_DELETE | NFS_ACCESS_LOOKUP;
+	else
+		cache.mask |= NFS_ACCESS_EXECUTE;
+	status = NFS_PROTO(inode)->access(inode, &cache, cred);
+	if (status != 0) {
+		if (status == -ESTALE) {
+			if (!S_ISDIR(inode->i_mode))
+				nfs_set_inode_stale(inode);
+			else
+				nfs_zap_caches(inode);
+		}
+		goto out;
+	}
+	nfs_access_add_cache(inode, &cache, cred);
+out_cached:
+	cache_mask = nfs_access_calc_mask(cache.mask, inode->i_mode);
+	if ((mask & ~cache_mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) != 0)
+		status = -EACCES;
+out:
+	trace_nfs_access_exit(inode, mask, cache_mask, status);
+	return status;
+}
+
+static int nfs_open_permission_mask(int openflags)
+{
+	int mask = 0;
+
+	if (openflags & __FMODE_EXEC) {
+		/* ONLY check exec rights */
+		mask = MAY_EXEC;
+	} else {
+		if ((openflags & O_ACCMODE) != O_WRONLY)
+			mask |= MAY_READ;
+		if ((openflags & O_ACCMODE) != O_RDONLY)
+			mask |= MAY_WRITE;
+	}
+
+	return mask;
+}
+
+int nfs_may_open(struct inode *inode, const struct cred *cred, int openflags)
+{
+	return nfs_do_access(inode, cred, nfs_open_permission_mask(openflags));
+}
+EXPORT_SYMBOL_GPL(nfs_may_open);
+
+static int nfs_execute_ok(struct inode *inode, int mask)
+{
+	struct nfs_server *server = NFS_SERVER(inode);
+	int ret = 0;
+
+	if (S_ISDIR(inode->i_mode))
+		return 0;
+	if (nfs_check_cache_invalid(inode, NFS_INO_INVALID_MODE)) {
+		if (mask & MAY_NOT_BLOCK)
+			return -ECHILD;
+		ret = __nfs_revalidate_inode(server, inode);
+	}
+	if (ret == 0 && !execute_ok(inode))
+		ret = -EACCES;
+	return ret;
+}
+
+int nfs_permission(struct mnt_idmap *idmap,
+		   struct inode *inode,
+		   int mask)
+{
+	const struct cred *cred = current_cred();
+	int res = 0;
+
+	nfs_inc_stats(inode, NFSIOS_VFSACCESS);
+
+	if ((mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
+		goto out;
+	/* Is this sys_access() ? */
+	if (mask & (MAY_ACCESS | MAY_CHDIR))
+		goto force_lookup;
+
+	switch (inode->i_mode & S_IFMT) {
+		case S_IFLNK:
+			goto out;
+		case S_IFREG:
+			if ((mask & MAY_OPEN) &&
+			   nfs_server_capable(inode, NFS_CAP_ATOMIC_OPEN))
+				return 0;
+			break;
+		case S_IFDIR:
+			/*
+			 * Optimize away all write operations, since the server
+			 * will check permissions when we perform the op.
+			 */
+			if ((mask & MAY_WRITE) && !(mask & MAY_READ))
+				goto out;
+	}
+
+force_lookup:
+	if (!NFS_PROTO(inode)->access)
+		goto out_notsup;
+
+	res = nfs_do_access(inode, cred, mask);
+out:
+	if (!res && (mask & MAY_EXEC))
+		res = nfs_execute_ok(inode, mask);
+
+	dfprintk(VFS, "NFS: permission(%s/%lu), mask=0x%x, res=%d\n",
+		inode->i_sb->s_id, inode->i_ino, mask, res);
+	return res;
+out_notsup:
+	if (mask & MAY_NOT_BLOCK)
+		return -ECHILD;
+
+	res = nfs_revalidate_inode(inode, NFS_INO_INVALID_MODE |
+						  NFS_INO_INVALID_OTHER);
+	if (res == 0)
+		res = generic_permission(&nop_mnt_idmap, inode, mask);
+	goto out;
+}
+EXPORT_SYMBOL_GPL(nfs_permission);