Initial import

1 files changed, 2520 insertions, 0 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
new file mode 100644
index 000000000..b2c8b31b2
--- /dev/null
+++ b/fs/nfs/dir.c
@@ -0,0 +1,2520 @@
+/*
+ *  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/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 "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 page*);
+
+const struct file_operations nfs_dir_operations = {
+	.llseek		= nfs_llseek_dir,
+	.read		= generic_read_dir,
+	.iterate	= nfs_readdir,
+	.open		= nfs_opendir,
+	.release	= nfs_closedir,
+	.fsync		= nfs_fsync_dir,
+};
+
+const struct address_space_operations nfs_dir_aops = {
+	.freepage = nfs_readdir_clear_array,
+};
+
+static struct nfs_open_dir_context *alloc_nfs_open_dir_context(struct inode *dir, struct rpc_cred *cred)
+{
+	struct nfs_inode *nfsi = NFS_I(dir);
+	struct nfs_open_dir_context *ctx;
+	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
+	if (ctx != NULL) {
+		ctx->duped = 0;
+		ctx->attr_gencount = nfsi->attr_gencount;
+		ctx->dir_cookie = 0;
+		ctx->dup_cookie = 0;
+		ctx->cred = get_rpccred(cred);
+		spin_lock(&dir->i_lock);
+		list_add(&ctx->list, &nfsi->open_files);
+		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(&ctx->list);
+	spin_unlock(&dir->i_lock);
+	put_rpccred(ctx->cred);
+	kfree(ctx);
+}
+
+/*
+ * Open file
+ */
+static int
+nfs_opendir(struct inode *inode, struct file *filp)
+{
+	int res = 0;
+	struct nfs_open_dir_context *ctx;
+	struct rpc_cred *cred;
+
+	dfprintk(FILE, "NFS: open dir(%pD2)\n", filp);
+
+	nfs_inc_stats(inode, NFSIOS_VFSOPEN);
+
+	cred = rpc_lookup_cred();
+	if (IS_ERR(cred))
+		return PTR_ERR(cred);
+	ctx = alloc_nfs_open_dir_context(inode, cred);
+	if (IS_ERR(ctx)) {
+		res = PTR_ERR(ctx);
+		goto out;
+	}
+	filp->private_data = ctx;
+	if (filp->f_path.dentry == filp->f_path.mnt->mnt_root) {
+		/* This is a mountpoint, so d_revalidate will never
+		 * have been called, so we need to refresh the
+		 * inode (for close-open consistency) ourselves.
+		 */
+		__nfs_revalidate_inode(NFS_SERVER(inode), inode);
+	}
+out:
+	put_rpccred(cred);
+	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;
+	struct qstr string;
+	unsigned char d_type;
+};
+
+struct nfs_cache_array {
+	int size;
+	int eof_index;
+	u64 last_cookie;
+	struct nfs_cache_array_entry array[0];
+};
+
+typedef int (*decode_dirent_t)(struct xdr_stream *, struct nfs_entry *, int);
+typedef struct {
+	struct file	*file;
+	struct page	*page;
+	struct dir_context *ctx;
+	unsigned long	page_index;
+	u64		*dir_cookie;
+	u64		last_cookie;
+	loff_t		current_index;
+	decode_dirent_t	decode;
+
+	unsigned long	timestamp;
+	unsigned long	gencount;
+	unsigned int	cache_entry_index;
+	unsigned int	plus:1;
+	unsigned int	eof:1;
+} nfs_readdir_descriptor_t;
+
+/*
+ * The caller is responsible for calling nfs_readdir_release_array(page)
+ */
+static
+struct nfs_cache_array *nfs_readdir_get_array(struct page *page)
+{
+	void *ptr;
+	if (page == NULL)
+		return ERR_PTR(-EIO);
+	ptr = kmap(page);
+	if (ptr == NULL)
+		return ERR_PTR(-ENOMEM);
+	return ptr;
+}
+
+static
+void nfs_readdir_release_array(struct page *page)
+{
+	kunmap(page);
+}
+
+/*
+ * we are freeing strings created by nfs_add_to_readdir_array()
+ */
+static
+void nfs_readdir_clear_array(struct page *page)
+{
+	struct nfs_cache_array *array;
+	int i;
+
+	array = kmap_atomic(page);
+	for (i = 0; i < array->size; i++)
+		kfree(array->array[i].string.name);
+	kunmap_atomic(array);
+}
+
+/*
+ * 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
+int nfs_readdir_make_qstr(struct qstr *string, const char *name, unsigned int len)
+{
+	string->len = len;
+	string->name = kmemdup(name, len, GFP_KERNEL);
+	if (string->name == NULL)
+		return -ENOMEM;
+	/*
+	 * Avoid a kmemleak false positive. The pointer to the name is stored
+	 * in a page cache page which kmemleak does not scan.
+	 */
+	kmemleak_not_leak(string->name);
+	string->hash = full_name_hash(name, len);
+	return 0;
+}
+
+static
+int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
+{
+	struct nfs_cache_array *array = nfs_readdir_get_array(page);
+	struct nfs_cache_array_entry *cache_entry;
+	int ret;
+
+	if (IS_ERR(array))
+		return PTR_ERR(array);
+
+	cache_entry = &array->array[array->size];
+
+	/* Check that this entry lies within the page bounds */
+	ret = -ENOSPC;
+	if ((char *)&cache_entry[1] - (char *)page_address(page) > PAGE_SIZE)
+		goto out;
+
+	cache_entry->cookie = entry->prev_cookie;
+	cache_entry->ino = entry->ino;
+	cache_entry->d_type = entry->d_type;
+	ret = nfs_readdir_make_qstr(&cache_entry->string, entry->name, entry->len);
+	if (ret)
+		goto out;
+	array->last_cookie = entry->cookie;
+	array->size++;
+	if (entry->eof != 0)
+		array->eof_index = array->size;
+out:
+	nfs_readdir_release_array(page);
+	return ret;
+}
+
+static
+int nfs_readdir_search_for_pos(struct nfs_cache_array *array, nfs_readdir_descriptor_t *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->eof_index >= 0)
+			goto out_eof;
+		return -EAGAIN;
+	}
+
+	index = (unsigned int)diff;
+	*desc->dir_cookie = array->array[index].cookie;
+	desc->cache_entry_index = index;
+	return 0;
+out_eof:
+	desc->eof = 1;
+	return -EBADCOOKIE;
+}
+
+static bool
+nfs_readdir_inode_mapping_valid(struct nfs_inode *nfsi)
+{
+	if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
+		return false;
+	smp_rmb();
+	return !test_bit(NFS_INO_INVALIDATING, &nfsi->flags);
+}
+
+static
+int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_descriptor_t *desc)
+{
+	int i;
+	loff_t new_pos;
+	int status = -EAGAIN;
+
+	for (i = 0; i < array->size; i++) {
+		if (array->array[i].cookie == *desc->dir_cookie) {
+			struct nfs_inode *nfsi = NFS_I(file_inode(desc->file));
+			struct nfs_open_dir_context *ctx = desc->file->private_data;
+
+			new_pos = desc->current_index + i;
+			if (ctx->attr_gencount != nfsi->attr_gencount ||
+			    !nfs_readdir_inode_mapping_valid(nfsi)) {
+				ctx->duped = 0;
+				ctx->attr_gencount = nfsi->attr_gencount;
+			} else if (new_pos < desc->ctx->pos) {
+				if (ctx->duped > 0
+				    && ctx->dup_cookie == *desc->dir_cookie) {
+					if (printk_ratelimit()) {
+						pr_notice("NFS: directory %pD2 contains a readdir loop."
+								"Please contact your server vendor.  "
+								"The file: %.*s has duplicate cookie %llu\n",
+								desc->file, array->array[i].string.len,
+								array->array[i].string.name, *desc->dir_cookie);
+					}
+					status = -ELOOP;
+					goto out;
+				}
+				ctx->dup_cookie = *desc->dir_cookie;
+				ctx->duped = -1;
+			}
+			desc->ctx->pos = new_pos;
+			desc->cache_entry_index = i;
+			return 0;
+		}
+	}
+	if (array->eof_index >= 0) {
+		status = -EBADCOOKIE;
+		if (*desc->dir_cookie == array->last_cookie)
+			desc->eof = 1;
+	}
+out:
+	return status;
+}
+
+static
+int nfs_readdir_search_array(nfs_readdir_descriptor_t *desc)
+{
+	struct nfs_cache_array *array;
+	int status;
+
+	array = nfs_readdir_get_array(desc->page);
+	if (IS_ERR(array)) {
+		status = PTR_ERR(array);
+		goto out;
+	}
+
+	if (*desc->dir_cookie == 0)
+		status = nfs_readdir_search_for_pos(array, desc);
+	else
+		status = nfs_readdir_search_for_cookie(array, desc);
+
+	if (status == -EAGAIN) {
+		desc->last_cookie = array->last_cookie;
+		desc->current_index += array->size;
+		desc->page_index++;
+	}
+	nfs_readdir_release_array(desc->page);
+out:
+	return status;
+}
+
+/* Fill a page with xdr information before transferring to the cache page */
+static
+int nfs_readdir_xdr_filler(struct page **pages, nfs_readdir_descriptor_t *desc,
+			struct nfs_entry *entry, struct file *file, struct inode *inode)
+{
+	struct nfs_open_dir_context *ctx = file->private_data;
+	struct rpc_cred	*cred = ctx->cred;
+	unsigned long	timestamp, gencount;
+	int		error;
+
+ again:
+	timestamp = jiffies;
+	gencount = nfs_inc_attr_generation_counter();
+	error = NFS_PROTO(inode)->readdir(file->f_path.dentry, cred, entry->cookie, pages,
+					  NFS_SERVER(inode)->dtsize, desc->plus);
+	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;
+			clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);
+			desc->plus = 0;
+			goto again;
+		}
+		goto error;
+	}
+	desc->timestamp = timestamp;
+	desc->gencount = gencount;
+error:
+	return error;
+}
+
+static int xdr_decode(nfs_readdir_descriptor_t *desc,
+		      struct nfs_entry *entry, struct xdr_stream *xdr)
+{
+	int error;
+
+	error = desc->decode(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 nfs_inode *nfsi;
+
+	if (d_really_is_negative(dentry))
+		return 0;
+
+	nfsi = NFS_I(d_inode(dentry));
+	if (entry->fattr->fileid == nfsi->fileid)
+		return 1;
+	if (nfs_compare_fh(entry->fh, &nfsi->fh) == 0)
+		return 1;
+	return 0;
+}
+
+static
+bool nfs_use_readdirplus(struct inode *dir, struct dir_context *ctx)
+{
+	if (!nfs_server_capable(dir, NFS_CAP_READDIRPLUS))
+		return false;
+	if (test_and_clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(dir)->flags))
+		return true;
+	if (ctx->pos == 0)
+		return true;
+	return false;
+}
+
+/*
+ * This function is called by the lookup code to request the use of
+ * readdirplus to accelerate any future lookups in the same
+ * directory.
+ */
+static
+void nfs_advise_use_readdirplus(struct inode *dir)
+{
+	set_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(dir)->flags);
+}
+
+/*
+ * This function is mainly for use by nfs_getattr().
+ *
+ * If this is an 'ls -l', we want to force use of readdirplus.
+ * Do this by checking if there is an active file descriptor
+ * and calling nfs_advise_use_readdirplus, then forcing a
+ * cache flush.
+ */
+void nfs_force_use_readdirplus(struct inode *dir)
+{
+	if (!list_empty(&NFS_I(dir)->open_files)) {
+		nfs_advise_use_readdirplus(dir);
+		nfs_zap_mapping(dir, dir->i_mapping);
+	}
+}
+
+static
+void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry)
+{
+	struct qstr filename = QSTR_INIT(entry->name, entry->len);
+	struct dentry *dentry;
+	struct dentry *alias;
+	struct inode *dir = d_inode(parent);
+	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.name[0] == '.') {
+		if (filename.len == 1)
+			return;
+		if (filename.len == 2 && filename.name[1] == '.')
+			return;
+	}
+	filename.hash = full_name_hash(filename.name, filename.len);
+
+	dentry = d_lookup(parent, &filename);
+	if (dentry != NULL) {
+		/* 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)) {
+			nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+			status = nfs_refresh_inode(d_inode(dentry), entry->fattr);
+			if (!status)
+				nfs_setsecurity(d_inode(dentry), entry->fattr, entry->label);
+			goto out;
+		} else {
+			d_invalidate(dentry);
+			dput(dentry);
+		}
+	}
+
+	dentry = d_alloc(parent, &filename);
+	if (dentry == NULL)
+		return;
+
+	inode = nfs_fhget(dentry->d_sb, entry->fh, entry->fattr, entry->label);
+	if (IS_ERR(inode))
+		goto out;
+
+	alias = d_splice_alias(inode, dentry);
+	if (IS_ERR(alias))
+		goto out;
+	else if (alias) {
+		nfs_set_verifier(alias, nfs_save_change_attribute(dir));
+		dput(alias);
+	} else
+		nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+
+out:
+	dput(dentry);
+}
+
+/* Perform conversion from xdr to cache array */
+static
+int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *entry,
+				struct page **xdr_pages, struct page *page, unsigned int buflen)
+{
+	struct xdr_stream stream;
+	struct xdr_buf buf;
+	struct page *scratch;
+	struct nfs_cache_array *array;
+	unsigned int count = 0;
+	int status;
+
+	scratch = alloc_page(GFP_KERNEL);
+	if (scratch == NULL)
+		return -ENOMEM;
+
+	if (buflen == 0)
+		goto out_nopages;
+
+	xdr_init_decode_pages(&stream, &buf, xdr_pages, buflen);
+	xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);
+
+	do {
+		status = xdr_decode(desc, entry, &stream);
+		if (status != 0) {
+			if (status == -EAGAIN)
+				status = 0;
+			break;
+		}
+
+		count++;
+
+		if (desc->plus != 0)
+			nfs_prime_dcache(desc->file->f_path.dentry, entry);
+
+		status = nfs_readdir_add_to_array(entry, page);
+		if (status != 0)
+			break;
+	} while (!entry->eof);
+
+out_nopages:
+	if (count == 0 || (status == -EBADCOOKIE && entry->eof != 0)) {
+		array = nfs_readdir_get_array(page);
+		if (!IS_ERR(array)) {
+			array->eof_index = array->size;
+			status = 0;
+			nfs_readdir_release_array(page);
+		} else
+			status = PTR_ERR(array);
+	}
+
+	put_page(scratch);
+	return status;
+}
+
+static
+void nfs_readdir_free_pagearray(struct page **pages, unsigned int npages)
+{
+	unsigned int i;
+	for (i = 0; i < npages; i++)
+		put_page(pages[i]);
+}
+
+static
+void nfs_readdir_free_large_page(void *ptr, struct page **pages,
+		unsigned int npages)
+{
+	nfs_readdir_free_pagearray(pages, npages);
+}
+
+/*
+ * nfs_readdir_large_page will allocate pages that must be freed with a call
+ * to nfs_readdir_free_large_page
+ */
+static
+int nfs_readdir_large_page(struct page **pages, unsigned int npages)
+{
+	unsigned int i;
+
+	for (i = 0; i < npages; i++) {
+		struct page *page = alloc_page(GFP_KERNEL);
+		if (page == NULL)
+			goto out_freepages;
+		pages[i] = page;
+	}
+	return 0;
+
+out_freepages:
+	nfs_readdir_free_pagearray(pages, i);
+	return -ENOMEM;
+}
+
+static
+int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page, struct inode *inode)
+{
+	struct page *pages[NFS_MAX_READDIR_PAGES];
+	void *pages_ptr = NULL;
+	struct nfs_entry entry;
+	struct file	*file = desc->file;
+	struct nfs_cache_array *array;
+	int status = -ENOMEM;
+	unsigned int array_size = ARRAY_SIZE(pages);
+
+	entry.prev_cookie = 0;
+	entry.cookie = desc->last_cookie;
+	entry.eof = 0;
+	entry.fh = nfs_alloc_fhandle();
+	entry.fattr = nfs_alloc_fattr();
+	entry.server = NFS_SERVER(inode);
+	if (entry.fh == NULL || entry.fattr == NULL)
+		goto out;
+
+	entry.label = nfs4_label_alloc(NFS_SERVER(inode), GFP_NOWAIT);
+	if (IS_ERR(entry.label)) {
+		status = PTR_ERR(entry.label);
+		goto out;
+	}
+
+	array = nfs_readdir_get_array(page);
+	if (IS_ERR(array)) {
+		status = PTR_ERR(array);
+		goto out_label_free;
+	}
+	memset(array, 0, sizeof(struct nfs_cache_array));
+	array->eof_index = -1;
+
+	status = nfs_readdir_large_page(pages, array_size);
+	if (status < 0)
+		goto out_release_array;
+	do {
+		unsigned int pglen;
+		status = nfs_readdir_xdr_filler(pages, desc, &entry, file, inode);
+
+		if (status < 0)
+			break;
+		pglen = status;
+		status = nfs_readdir_page_filler(desc, &entry, pages, page, pglen);
+		if (status < 0) {
+			if (status == -ENOSPC)
+				status = 0;
+			break;
+		}
+	} while (array->eof_index < 0);
+
+	nfs_readdir_free_large_page(pages_ptr, pages, array_size);
+out_release_array:
+	nfs_readdir_release_array(page);
+out_label_free:
+	nfs4_label_free(entry.label);
+out:
+	nfs_free_fattr(entry.fattr);
+	nfs_free_fhandle(entry.fh);
+	return status;
+}
+
+/*
+ * Now we cache directories properly, by converting xdr information
+ * to an array that can be used for lookups later.  This results in
+ * fewer cache pages, since we can store more information on each page.
+ * We only need to convert from xdr once so future lookups are much simpler
+ */
+static
+int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page* page)
+{
+	struct inode	*inode = file_inode(desc->file);
+	int ret;
+
+	ret = nfs_readdir_xdr_to_array(desc, page, inode);
+	if (ret < 0)
+		goto error;
+	SetPageUptodate(page);
+
+	if (invalidate_inode_pages2_range(inode->i_mapping, page->index + 1, -1) < 0) {
+		/* Should never happen */
+		nfs_zap_mapping(inode, inode->i_mapping);
+	}
+	unlock_page(page);
+	return 0;
+ error:
+	unlock_page(page);
+	return ret;
+}
+
+static
+void cache_page_release(nfs_readdir_descriptor_t *desc)
+{
+	if (!desc->page->mapping)
+		nfs_readdir_clear_array(desc->page);
+	page_cache_release(desc->page);
+	desc->page = NULL;
+}
+
+static
+struct page *get_cache_page(nfs_readdir_descriptor_t *desc)
+{
+	return read_cache_page(file_inode(desc->file)->i_mapping,
+			desc->page_index, (filler_t *)nfs_readdir_filler, desc);
+}
+
+/*
+ * Returns 0 if desc->dir_cookie was found on page desc->page_index
+ */
+static
+int find_cache_page(nfs_readdir_descriptor_t *desc)
+{
+	int res;
+
+	desc->page = get_cache_page(desc);
+	if (IS_ERR(desc->page))
+		return PTR_ERR(desc->page);
+
+	res = nfs_readdir_search_array(desc);
+	if (res != 0)
+		cache_page_release(desc);
+	return res;
+}
+
+/* Search for desc->dir_cookie from the beginning of the page cache */
+static inline
+int readdir_search_pagecache(nfs_readdir_descriptor_t *desc)
+{
+	int res;
+
+	if (desc->page_index == 0) {
+		desc->current_index = 0;
+		desc->last_cookie = 0;
+	}
+	do {
+		res = find_cache_page(desc);
+	} while (res == -EAGAIN);
+	return res;
+}
+
+/*
+ * Once we've found the start of the dirent within a page: fill 'er up...
+ */
+static 
+int nfs_do_filldir(nfs_readdir_descriptor_t *desc)
+{
+	struct file	*file = desc->file;
+	int i = 0;
+	int res = 0;
+	struct nfs_cache_array *array = NULL;
+	struct nfs_open_dir_context *ctx = file->private_data;
+
+	array = nfs_readdir_get_array(desc->page);
+	if (IS_ERR(array)) {
+		res = PTR_ERR(array);
+		goto out;
+	}
+
+	for (i = desc->cache_entry_index; i < array->size; i++) {
+		struct nfs_cache_array_entry *ent;
+
+		ent = &array->array[i];
+		if (!dir_emit(desc->ctx, ent->string.name, ent->string.len,
+		    nfs_compat_user_ino64(ent->ino), ent->d_type)) {
+			desc->eof = 1;
+			break;
+		}
+		desc->ctx->pos++;
+		if (i < (array->size-1))
+			*desc->dir_cookie = array->array[i+1].cookie;
+		else
+			*desc->dir_cookie = array->last_cookie;
+		if (ctx->duped != 0)
+			ctx->duped = 1;
+	}
+	if (array->eof_index >= 0)
+		desc->eof = 1;
+
+	nfs_readdir_release_array(desc->page);
+out:
+	cache_page_release(desc);
+	dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n",
+			(unsigned long long)*desc->dir_cookie, res);
+	return res;
+}
+
+/*
+ * 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 inline
+int uncached_readdir(nfs_readdir_descriptor_t *desc)
+{
+	struct page	*page = NULL;
+	int		status;
+	struct inode *inode = file_inode(desc->file);
+	struct nfs_open_dir_context *ctx = desc->file->private_data;
+
+	dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %Lu\n",
+			(unsigned long long)*desc->dir_cookie);
+
+	page = alloc_page(GFP_HIGHUSER);
+	if (!page) {
+		status = -ENOMEM;
+		goto out;
+	}
+
+	desc->page_index = 0;
+	desc->last_cookie = *desc->dir_cookie;
+	desc->page = page;
+	ctx->duped = 0;
+
+	status = nfs_readdir_xdr_to_array(desc, page, inode);
+	if (status < 0)
+		goto out_release;
+
+	status = nfs_do_filldir(desc);
+
+ out:
+	dfprintk(DIRCACHE, "NFS: %s: returns %d\n",
+			__func__, status);
+	return status;
+ out_release:
+	cache_page_release(desc);
+	goto out;
+}
+
+static bool nfs_dir_mapping_need_revalidate(struct inode *dir)
+{
+	struct nfs_inode *nfsi = NFS_I(dir);
+
+	if (nfs_attribute_cache_expired(dir))
+		return true;
+	if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
+		return true;
+	return false;
+}
+
+/* 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->f_path.dentry;
+	struct inode	*inode = d_inode(dentry);
+	nfs_readdir_descriptor_t my_desc,
+			*desc = &my_desc;
+	struct nfs_open_dir_context *dir_ctx = file->private_data;
+	int res = 0;
+
+	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.
+	 */
+	memset(desc, 0, sizeof(*desc));
+
+	desc->file = file;
+	desc->ctx = ctx;
+	desc->dir_cookie = &dir_ctx->dir_cookie;
+	desc->decode = NFS_PROTO(inode)->decode_dirent;
+	desc->plus = nfs_use_readdirplus(inode, ctx) ? 1 : 0;
+
+	nfs_block_sillyrename(dentry);
+	if (ctx->pos == 0 || nfs_dir_mapping_need_revalidate(inode))
+		res = nfs_revalidate_mapping(inode, file->f_mapping);
+	if (res < 0)
+		goto out;
+
+	do {
+		res = readdir_search_pagecache(desc);
+
+		if (res == -EBADCOOKIE) {
+			res = 0;
+			/* This means either end of directory */
+			if (*desc->dir_cookie && desc->eof == 0) {
+				/* Or that the server has 'lost' a cookie */
+				res = uncached_readdir(desc);
+				if (res == 0)
+					continue;
+			}
+			break;
+		}
+		if (res == -ETOOSMALL && desc->plus) {
+			clear_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);
+			nfs_zap_caches(inode);
+			desc->page_index = 0;
+			desc->plus = 0;
+			desc->eof = 0;
+			continue;
+		}
+		if (res < 0)
+			break;
+
+		res = nfs_do_filldir(desc);
+		if (res < 0)
+			break;
+	} while (!desc->eof);
+out:
+	nfs_unblock_sillyrename(dentry);
+	if (res > 0)
+		res = 0;
+	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 inode *inode = file_inode(filp);
+	struct nfs_open_dir_context *dir_ctx = filp->private_data;
+
+	dfprintk(FILE, "NFS: llseek dir(%pD2, %lld, %d)\n",
+			filp, offset, whence);
+
+	mutex_lock(&inode->i_mutex);
+	switch (whence) {
+		case 1:
+			offset += filp->f_pos;
+		case 0:
+			if (offset >= 0)
+				break;
+		default:
+			offset = -EINVAL;
+			goto out;
+	}
+	if (offset != filp->f_pos) {
+		filp->f_pos = offset;
+		dir_ctx->dir_cookie = 0;
+		dir_ctx->duped = 0;
+	}
+out:
+	mutex_unlock(&inode->i_mutex);
+	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)
+{
+	struct inode *inode = file_inode(filp);
+
+	dfprintk(FILE, "NFS: fsync dir(%pD2) datasync %d\n", filp, datasync);
+
+	mutex_lock(&inode->i_mutex);
+	nfs_inc_stats(inode, NFSIOS_VFSFSYNC);
+	mutex_unlock(&inode->i_mutex);
+	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.
+ *
+ * The caller should be holding dir->i_lock
+ */
+void nfs_force_lookup_revalidate(struct inode *dir)
+{
+	NFS_I(dir)->cache_change_attribute++;
+}
+EXPORT_SYMBOL_GPL(nfs_force_lookup_revalidate);
+
+/*
+ * 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)
+{
+	int ret;
+
+	if (IS_ROOT(dentry))
+		return 1;
+	if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
+		return 0;
+	if (!nfs_verify_change_attribute(dir, dentry->d_time))
+		return 0;
+	/* Revalidate nfsi->cache_change_attribute before we declare a match */
+	if (rcu_walk)
+		ret = nfs_revalidate_inode_rcu(NFS_SERVER(dir), dir);
+	else
+		ret = nfs_revalidate_inode(NFS_SERVER(dir), dir);
+	if (ret < 0)
+		return 0;
+	if (!nfs_verify_change_attribute(dir, dentry->d_time))
+		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;
+	/* VFS wants an on-the-wire revalidation */
+	if (flags & LOOKUP_REVAL)
+		goto out_force;
+	/* This is an open(2) */
+	if ((flags & LOOKUP_OPEN) && !(server->flags & NFS_MOUNT_NOCTO) &&
+	    (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
+		goto out_force;
+out:
+	return (inode->i_nlink == 0) ? -ENOENT : 0;
+out_force:
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+	ret = __nfs_revalidate_inode(server, inode);
+	if (ret != 0)
+		return ret;
+	goto out;
+}
+
+/*
+ * 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.
+ */
+static inline
+int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
+		       unsigned int flags)
+{
+	/* Don't revalidate a negative dentry if we're creating a new file */
+	if (flags & LOOKUP_CREATE)
+		return 0;
+	if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG)
+		return 1;
+	return !nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU);
+}
+
+/*
+ * 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_lookup_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct inode *dir;
+	struct inode *inode;
+	struct dentry *parent;
+	struct nfs_fh *fhandle = NULL;
+	struct nfs_fattr *fattr = NULL;
+	struct nfs4_label *label = NULL;
+	int error;
+
+	if (flags & LOOKUP_RCU) {
+		parent = ACCESS_ONCE(dentry->d_parent);
+		dir = d_inode_rcu(parent);
+		if (!dir)
+			return -ECHILD;
+	} else {
+		parent = dget_parent(dentry);
+		dir = d_inode(parent);
+	}
+	nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE);
+	inode = d_inode(dentry);
+
+	if (!inode) {
+		if (nfs_neg_need_reval(dir, dentry, flags)) {
+			if (flags & LOOKUP_RCU)
+				return -ECHILD;
+			goto out_bad;
+		}
+		goto out_valid_noent;
+	}
+
+	if (is_bad_inode(inode)) {
+		if (flags & LOOKUP_RCU)
+			return -ECHILD;
+		dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n",
+				__func__, dentry);
+		goto out_bad;
+	}
+
+	if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ))
+		goto out_set_verifier;
+
+	/* Force a full look up iff the parent directory has changed */
+	if (!nfs_is_exclusive_create(dir, flags) &&
+	    nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) {
+
+		if (nfs_lookup_verify_inode(inode, flags)) {
+			if (flags & LOOKUP_RCU)
+				return -ECHILD;
+			goto out_zap_parent;
+		}
+		goto out_valid;
+	}
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	if (NFS_STALE(inode))
+		goto out_bad;
+
+	error = -ENOMEM;
+	fhandle = nfs_alloc_fhandle();
+	fattr = nfs_alloc_fattr();
+	if (fhandle == NULL || fattr == NULL)
+		goto out_error;
+
+	label = nfs4_label_alloc(NFS_SERVER(inode), GFP_NOWAIT);
+	if (IS_ERR(label))
+		goto out_error;
+
+	trace_nfs_lookup_revalidate_enter(dir, dentry, flags);
+	error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label);
+	trace_nfs_lookup_revalidate_exit(dir, dentry, flags, error);
+	if (error)
+		goto out_bad;
+	if (nfs_compare_fh(NFS_FH(inode), fhandle))
+		goto out_bad;
+	if ((error = nfs_refresh_inode(inode, fattr)) != 0)
+		goto out_bad;
+
+	nfs_setsecurity(inode, fattr, label);
+
+	nfs_free_fattr(fattr);
+	nfs_free_fhandle(fhandle);
+	nfs4_label_free(label);
+
+out_set_verifier:
+	nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+ out_valid:
+	/* Success: notify readdir to use READDIRPLUS */
+	nfs_advise_use_readdirplus(dir);
+ out_valid_noent:
+	if (flags & LOOKUP_RCU) {
+		if (parent != ACCESS_ONCE(dentry->d_parent))
+			return -ECHILD;
+	} else
+		dput(parent);
+	dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is valid\n",
+			__func__, dentry);
+	return 1;
+out_zap_parent:
+	nfs_zap_caches(dir);
+ out_bad:
+	WARN_ON(flags & LOOKUP_RCU);
+	nfs_free_fattr(fattr);
+	nfs_free_fhandle(fhandle);
+	nfs4_label_free(label);
+	nfs_mark_for_revalidate(dir);
+	if (inode && S_ISDIR(inode->i_mode)) {
+		/* Purge readdir caches. */
+		nfs_zap_caches(inode);
+		/*
+		 * 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 (IS_ROOT(dentry))
+			goto out_valid;
+	}
+	dput(parent);
+	dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is invalid\n",
+			__func__, dentry);
+	return 0;
+out_error:
+	WARN_ON(flags & LOOKUP_RCU);
+	nfs_free_fattr(fattr);
+	nfs_free_fhandle(fhandle);
+	nfs4_label_free(label);
+	dput(parent);
+	dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) lookup returned error %d\n",
+			__func__, dentry, error);
+	return error;
+}
+
+/*
+ * 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)
+{
+	int error;
+	struct inode *inode = d_inode(dentry);
+
+	/*
+	 * 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_revalidate_inode(NFS_SERVER(inode), inode);
+	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 & MS_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 == 1)
+		clear_nlink(inode);
+	NFS_I(inode)->cache_validity |= NFS_INO_INVALID_ATTR;
+	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 (S_ISDIR(inode->i_mode))
+		/* drop any readdir cache as it could easily be old */
+		NFS_I(inode)->cache_validity |= NFS_INO_INVALID_DATA;
+
+	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 dentry *parent;
+	struct inode *inode = NULL;
+	struct nfs_fh *fhandle = NULL;
+	struct nfs_fattr *fattr = NULL;
+	struct nfs4_label *label = NULL;
+	int error;
+
+	dfprintk(VFS, "NFS: lookup(%pd2)\n", dentry);
+	nfs_inc_stats(dir, NFSIOS_VFSLOOKUP);
+
+	res = ERR_PTR(-ENAMETOOLONG);
+	if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
+		goto out;
+
+	/*
+	 * If we're doing an exclusive create, optimize away the lookup
+	 * but don't hash the dentry.
+	 */
+	if (nfs_is_exclusive_create(dir, flags)) {
+		d_instantiate(dentry, NULL);
+		res = NULL;
+		goto out;
+	}
+
+	res = ERR_PTR(-ENOMEM);
+	fhandle = nfs_alloc_fhandle();
+	fattr = nfs_alloc_fattr();
+	if (fhandle == NULL || fattr == NULL)
+		goto out;
+
+	label = nfs4_label_alloc(NFS_SERVER(dir), GFP_NOWAIT);
+	if (IS_ERR(label))
+		goto out;
+
+	parent = dentry->d_parent;
+	/* Protect against concurrent sillydeletes */
+	trace_nfs_lookup_enter(dir, dentry, flags);
+	nfs_block_sillyrename(parent);
+	error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label);
+	if (error == -ENOENT)
+		goto no_entry;
+	if (error < 0) {
+		res = ERR_PTR(error);
+		goto out_unblock_sillyrename;
+	}
+	inode = nfs_fhget(dentry->d_sb, fhandle, fattr, label);
+	res = ERR_CAST(inode);
+	if (IS_ERR(res))
+		goto out_unblock_sillyrename;
+
+	/* Success: notify readdir to use READDIRPLUS */
+	nfs_advise_use_readdirplus(dir);
+
+no_entry:
+	res = d_splice_alias(inode, dentry);
+	if (res != NULL) {
+		if (IS_ERR(res))
+			goto out_unblock_sillyrename;
+		dentry = res;
+	}
+	nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+out_unblock_sillyrename:
+	nfs_unblock_sillyrename(parent);
+	trace_nfs_lookup_exit(dir, dentry, flags, error);
+	nfs4_label_free(label);
+out:
+	nfs_free_fattr(fattr);
+	nfs_free_fhandle(fhandle);
+	return res;
+}
+EXPORT_SYMBOL_GPL(nfs_lookup);
+
+#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_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 fmode_t flags_to_mode(int flags)
+{
+	fmode_t res = (__force fmode_t)flags & FMODE_EXEC;
+	if ((flags & O_ACCMODE) != O_WRONLY)
+		res |= FMODE_READ;
+	if ((flags & O_ACCMODE) != O_RDONLY)
+		res |= FMODE_WRITE;
+	return res;
+}
+
+static struct nfs_open_context *create_nfs_open_context(struct dentry *dentry, int open_flags)
+{
+	return alloc_nfs_open_context(dentry, flags_to_mode(open_flags));
+}
+
+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 *opened)
+{
+	int err;
+
+	if ((open_flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
+		*opened |= FILE_CREATED;
+
+	err = finish_open(file, dentry, do_open, opened);
+	if (err)
+		goto out;
+	nfs_file_set_open_context(file, ctx);
+
+out:
+	return err;
+}
+
+int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
+		    struct file *file, unsigned open_flags,
+		    umode_t mode, int *opened)
+{
+	struct nfs_open_context *ctx;
+	struct dentry *res;
+	struct iattr attr = { .ia_valid = ATTR_OPEN };
+	struct inode *inode;
+	unsigned int lookup_flags = 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_unhashed(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) {
+		attr.ia_valid |= ATTR_MODE;
+		attr.ia_mode = mode & ~current_umask();
+	}
+	if (open_flags & O_TRUNC) {
+		attr.ia_valid |= ATTR_SIZE;
+		attr.ia_size = 0;
+	}
+
+	ctx = create_nfs_open_context(dentry, open_flags);
+	err = PTR_ERR(ctx);
+	if (IS_ERR(ctx))
+		goto out;
+
+	trace_nfs_atomic_open_enter(dir, ctx, open_flags);
+	nfs_block_sillyrename(dentry->d_parent);
+	inode = NFS_PROTO(dir)->open_context(dir, ctx, open_flags, &attr, opened);
+	nfs_unblock_sillyrename(dentry->d_parent);
+	if (IS_ERR(inode)) {
+		err = PTR_ERR(inode);
+		trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
+		put_nfs_open_context(ctx);
+		switch (err) {
+		case -ENOENT:
+			d_drop(dentry);
+			d_add(dentry, NULL);
+			nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+			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;
+	}
+
+	err = nfs_finish_open(ctx, ctx->dentry, file, open_flags, opened);
+	trace_nfs_atomic_open_exit(dir, ctx, open_flags, err);
+	put_nfs_open_context(ctx);
+out:
+	return err;
+
+no_open:
+	res = nfs_lookup(dir, dentry, lookup_flags);
+	err = PTR_ERR(res);
+	if (IS_ERR(res))
+		goto out;
+
+	return finish_no_open(file, res);
+}
+EXPORT_SYMBOL_GPL(nfs_atomic_open);
+
+static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct inode *inode;
+	int ret = 0;
+
+	if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY))
+		goto no_open;
+	if (d_mountpoint(dentry))
+		goto no_open;
+	if (NFS_SB(dentry->d_sb)->caps & NFS_CAP_ATOMIC_OPEN_V1)
+		goto no_open;
+
+	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) {
+		struct dentry *parent;
+		struct inode *dir;
+
+		if (flags & LOOKUP_RCU) {
+			parent = ACCESS_ONCE(dentry->d_parent);
+			dir = d_inode_rcu(parent);
+			if (!dir)
+				return -ECHILD;
+		} else {
+			parent = dget_parent(dentry);
+			dir = d_inode(parent);
+		}
+		if (!nfs_neg_need_reval(dir, dentry, flags))
+			ret = 1;
+		else if (flags & LOOKUP_RCU)
+			ret = -ECHILD;
+		if (!(flags & LOOKUP_RCU))
+			dput(parent);
+		else if (parent != ACCESS_ONCE(dentry->d_parent))
+			return -ECHILD;
+		goto out;
+	}
+
+	/* NFS only supports OPEN on regular files */
+	if (!S_ISREG(inode->i_mode))
+		goto no_open;
+	/* We cannot do exclusive creation on a positive dentry */
+	if (flags & LOOKUP_EXCL)
+		goto no_open;
+
+	/* Let f_op->open() actually open (and revalidate) the file */
+	ret = 1;
+
+out:
+	return ret;
+
+no_open:
+	return nfs_lookup_revalidate(dentry, flags);
+}
+
+#endif /* CONFIG_NFSV4 */
+
+/*
+ * Code common to create, mkdir, and mknod.
+ */
+int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
+				struct nfs_fattr *fattr,
+				struct nfs4_label *label)
+{
+	struct dentry *parent = dget_parent(dentry);
+	struct inode *dir = d_inode(parent);
+	struct inode *inode;
+	int error = -EACCES;
+
+	d_drop(dentry);
+
+	/* We may have been initialized further down */
+	if (d_really_is_positive(dentry))
+		goto out;
+	if (fhandle->size == 0) {
+		error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, NULL);
+		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, label);
+	error = PTR_ERR(inode);
+	if (IS_ERR(inode))
+		goto out_error;
+	d_add(dentry, inode);
+out:
+	dput(parent);
+	return 0;
+out_error:
+	nfs_mark_for_revalidate(dir);
+	dput(parent);
+	return error;
+}
+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 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 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);
+
+	if (!new_valid_dev(rdev))
+		return -EINVAL;
+
+	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 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 (d_really_is_positive(dentry) && !d_unhashed(dentry))
+		d_delete(dentry);
+}
+
+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)) {
+		nfs_wait_on_sillyrename(dentry);
+		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);
+		}
+	} else
+		error = NFS_PROTO(dir)->rmdir(dir, &dentry->d_name);
+	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) {
+		NFS_PROTO(inode)->return_delegation(inode);
+		error = NFS_PROTO(dir)->remove(dir, &dentry->d_name);
+		if (error == 0)
+			nfs_drop_nlink(inode);
+	} else
+		error = NFS_PROTO(dir)->remove(dir, &dentry->d_name);
+	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;
+	int need_rehash = 0;
+
+	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) {
+		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;
+	}
+	if (!d_unhashed(dentry)) {
+		__d_drop(dentry);
+		need_rehash = 1;
+	}
+	spin_unlock(&dentry->d_lock);
+	error = nfs_safe_remove(dentry);
+	if (!error || error == -ENOENT) {
+		nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
+	} else if (need_rehash)
+		d_rehash(dentry);
+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 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_HIGHUSER);
+	if (!page)
+		return -ENOMEM;
+
+	kaddr = kmap_atomic(page);
+	memcpy(kaddr, symname, pathlen);
+	if (pathlen < PAGE_SIZE)
+		memset(kaddr + pathlen, 0, PAGE_SIZE - pathlen);
+	kunmap_atomic(kaddr);
+
+	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;
+	}
+
+	/*
+	 * 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.
+		 */
+		page_cache_release(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);
+	NFS_PROTO(inode)->return_delegation(inode);
+
+	d_drop(dentry);
+	error = NFS_PROTO(dir)->link(inode, dir, &dentry->d_name);
+	if (error == 0) {
+		ihold(inode);
+		d_add(dentry, inode);
+	}
+	trace_nfs_link_exit(inode, dir, dentry, error);
+	return error;
+}
+EXPORT_SYMBOL_GPL(nfs_link);
+
+/*
+ * 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 inode *old_dir, struct dentry *old_dentry,
+		      struct inode *new_dir, struct dentry *new_dentry)
+{
+	struct inode *old_inode = d_inode(old_dentry);
+	struct inode *new_inode = d_inode(new_dentry);
+	struct dentry *dentry = NULL, *rehash = NULL;
+	struct rpc_task *task;
+	int error = -EBUSY;
+
+	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)) {
+		/*
+		 * To prevent any new references to the target during the
+		 * rename, we unhash the dentry in advance.
+		 */
+		if (!d_unhashed(new_dentry)) {
+			d_drop(new_dentry);
+			rehash = new_dentry;
+		}
+
+		if (d_count(new_dentry) > 2) {
+			int err;
+
+			/* 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;
+			rehash = NULL;
+			new_inode = NULL;
+		}
+	}
+
+	NFS_PROTO(old_inode)->return_delegation(old_inode);
+	if (new_inode != NULL)
+		NFS_PROTO(new_inode)->return_delegation(new_inode);
+
+	task = nfs_async_rename(old_dir, new_dir, old_dentry, new_dentry, NULL);
+	if (IS_ERR(task)) {
+		error = PTR_ERR(task);
+		goto out;
+	}
+
+	error = rpc_wait_for_completion_task(task);
+	if (error == 0)
+		error = task->tk_status;
+	rpc_put_task(task);
+	nfs_mark_for_revalidate(old_inode);
+out:
+	if (rehash)
+		d_rehash(rehash);
+	trace_nfs_rename_exit(old_dir, old_dentry,
+			new_dir, new_dentry, error);
+	if (!error) {
+		if (new_inode != NULL)
+			nfs_drop_nlink(new_inode);
+		d_move(old_dentry, new_dentry);
+		nfs_set_verifier(new_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 = ULONG_MAX;
+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_rpccred(entry->cred);
+	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 struct nfs_access_entry *nfs_access_search_rbtree(struct inode *inode, struct rpc_cred *cred)
+{
+	struct rb_node *n = NFS_I(inode)->access_cache.rb_node;
+	struct nfs_access_entry *entry;
+
+	while (n != NULL) {
+		entry = rb_entry(n, struct nfs_access_entry, rb_node);
+
+		if (cred < entry->cred)
+			n = n->rb_left;
+		else if (cred > entry->cred)
+			n = n->rb_right;
+		else
+			return entry;
+	}
+	return NULL;
+}
+
+static int nfs_access_get_cached(struct inode *inode, struct rpc_cred *cred, struct nfs_access_entry *res)
+{
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct nfs_access_entry *cache;
+	int err = -ENOENT;
+
+	spin_lock(&inode->i_lock);
+	if (nfsi->cache_validity & NFS_INO_INVALID_ACCESS)
+		goto out_zap;
+	cache = nfs_access_search_rbtree(inode, cred);
+	if (cache == NULL)
+		goto out;
+	if (!nfs_have_delegated_attributes(inode) &&
+	    !time_in_range_open(jiffies, cache->jiffies, cache->jiffies + nfsi->attrtimeo))
+		goto out_stale;
+	res->jiffies = cache->jiffies;
+	res->cred = cache->cred;
+	res->mask = cache->mask;
+	list_move_tail(&cache->lru, &nfsi->access_cache_entry_lru);
+	err = 0;
+out:
+	spin_unlock(&inode->i_lock);
+	return err;
+out_stale:
+	rb_erase(&cache->rb_node, &nfsi->access_cache);
+	list_del(&cache->lru);
+	spin_unlock(&inode->i_lock);
+	nfs_access_free_entry(cache);
+	return -ENOENT;
+out_zap:
+	spin_unlock(&inode->i_lock);
+	nfs_access_zap_cache(inode);
+	return -ENOENT;
+}
+
+static int nfs_access_get_cached_rcu(struct inode *inode, struct rpc_cred *cred, struct nfs_access_entry *res)
+{
+	/* Only check the most recently returned cache entry,
+	 * but do it without locking.
+	 */
+	struct nfs_inode *nfsi = NFS_I(inode);
+	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(nfsi->access_cache_entry_lru.prev);
+	cache = list_entry(lh, struct nfs_access_entry, lru);
+	if (lh == &nfsi->access_cache_entry_lru ||
+	    cred != cache->cred)
+		cache = NULL;
+	if (cache == NULL)
+		goto out;
+	if (!nfs_have_delegated_attributes(inode) &&
+	    !time_in_range_open(jiffies, cache->jiffies, cache->jiffies + nfsi->attrtimeo))
+		goto out;
+	res->jiffies = cache->jiffies;
+	res->cred = cache->cred;
+	res->mask = cache->mask;
+	err = 0;
+out:
+	rcu_read_unlock();
+	return err;
+}
+
+static void nfs_access_add_rbtree(struct inode *inode, struct nfs_access_entry *set)
+{
+	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;
+
+	spin_lock(&inode->i_lock);
+	while (*p != NULL) {
+		parent = *p;
+		entry = rb_entry(parent, struct nfs_access_entry, rb_node);
+
+		if (set->cred < entry->cred)
+			p = &parent->rb_left;
+		else if (set->cred > entry->cred)
+			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)
+{
+	struct nfs_access_entry *cache = kmalloc(sizeof(*cache), GFP_KERNEL);
+	if (cache == NULL)
+		return;
+	RB_CLEAR_NODE(&cache->rb_node);
+	cache->jiffies = set->jiffies;
+	cache->cred = get_rpccred(set->cred);
+	cache->mask = set->mask;
+
+	/* 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);
+
+	/* 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);
+
+void nfs_access_set_mask(struct nfs_access_entry *entry, u32 access_result)
+{
+	entry->mask = 0;
+	if (access_result & NFS4_ACCESS_READ)
+		entry->mask |= MAY_READ;
+	if (access_result &
+	    (NFS4_ACCESS_MODIFY | NFS4_ACCESS_EXTEND | NFS4_ACCESS_DELETE))
+		entry->mask |= MAY_WRITE;
+	if (access_result & (NFS4_ACCESS_LOOKUP|NFS4_ACCESS_EXECUTE))
+		entry->mask |= MAY_EXEC;
+}
+EXPORT_SYMBOL_GPL(nfs_access_set_mask);
+
+static int nfs_do_access(struct inode *inode, struct rpc_cred *cred, int mask)
+{
+	struct nfs_access_entry cache;
+	int status;
+
+	trace_nfs_access_enter(inode);
+
+	status = nfs_access_get_cached_rcu(inode, cred, &cache);
+	if (status != 0)
+		status = nfs_access_get_cached(inode, cred, &cache);
+	if (status == 0)
+		goto out_cached;
+
+	status = -ECHILD;
+	if (mask & MAY_NOT_BLOCK)
+		goto out;
+
+	/* Be clever: ask server to check for all possible rights */
+	cache.mask = MAY_EXEC | MAY_WRITE | MAY_READ;
+	cache.cred = cred;
+	cache.jiffies = jiffies;
+	status = NFS_PROTO(inode)->access(inode, &cache);
+	if (status != 0) {
+		if (status == -ESTALE) {
+			nfs_zap_caches(inode);
+			if (!S_ISDIR(inode->i_mode))
+				set_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
+		}
+		goto out;
+	}
+	nfs_access_add_cache(inode, &cache);
+out_cached:
+	if ((mask & ~cache.mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) != 0)
+		status = -EACCES;
+out:
+	trace_nfs_access_exit(inode, 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, struct rpc_cred *cred, int openflags)
+{
+	return nfs_do_access(inode, cred, nfs_open_permission_mask(openflags));
+}
+EXPORT_SYMBOL_GPL(nfs_may_open);
+
+int nfs_permission(struct inode *inode, int mask)
+{
+	struct rpc_cred *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:
+			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;
+
+	/* Always try fast lookups first */
+	rcu_read_lock();
+	cred = rpc_lookup_cred_nonblock();
+	if (!IS_ERR(cred))
+		res = nfs_do_access(inode, cred, mask|MAY_NOT_BLOCK);
+	else
+		res = PTR_ERR(cred);
+	rcu_read_unlock();
+	if (res == -ECHILD && !(mask & MAY_NOT_BLOCK)) {
+		/* Fast lookup failed, try the slow way */
+		cred = rpc_lookup_cred();
+		if (!IS_ERR(cred)) {
+			res = nfs_do_access(inode, cred, mask);
+			put_rpccred(cred);
+		} else
+			res = PTR_ERR(cred);
+	}
+out:
+	if (!res && (mask & MAY_EXEC) && !execute_ok(inode))
+		res = -EACCES;
+
+	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(NFS_SERVER(inode), inode);
+	if (res == 0)
+		res = generic_permission(inode, mask);
+	goto out;
+}
+EXPORT_SYMBOL_GPL(nfs_permission);
+
+/*
+ * Local variables:
+ *  version-control: t
+ *  kept-new-versions: 5
+ * End:
+ */