Merge tag 'nfs-for-3.17-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client updates from Trond Myklebust:
 "Highlights include:

   - stable fix for a bug in nfs3_list_one_acl()
   - speed up NFS path walks by supporting LOOKUP_RCU
   - more read/write code cleanups
   - pNFS fixes for layout return on close
   - fixes for the RCU handling in the rpcsec_gss code
   - more NFS/RDMA fixes"

* tag 'nfs-for-3.17-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (79 commits)
  nfs: reject changes to resvport and sharecache during remount
  NFS: Avoid infinite loop when RELEASE_LOCKOWNER getting expired error
  SUNRPC: remove all refcounting of groupinfo from rpcauth_lookupcred
  NFS: fix two problems in lookup_revalidate in RCU-walk
  NFS: allow lockless access to access_cache
  NFS: teach nfs_lookup_verify_inode to handle LOOKUP_RCU
  NFS: teach nfs_neg_need_reval to understand LOOKUP_RCU
  NFS: support RCU_WALK in nfs_permission()
  sunrpc/auth: allow lockless (rcu) lookup of credential cache.
  NFS: prepare for RCU-walk support but pushing tests later in code.
  NFS: nfs4_lookup_revalidate: only evaluate parent if it will be used.
  NFS: add checks for returned value of try_module_get()
  nfs: clear_request_commit while holding i_lock
  pnfs: add pnfs_put_lseg_async
  pnfs: find swapped pages on pnfs commit lists too
  nfs: fix comment and add warn_on for PG_INODE_REF
  nfs: check wait_on_bit_lock err in page_group_lock
  sunrpc: remove "ec" argument from encrypt_v2 operation
  sunrpc: clean up sparse endianness warnings in gss_krb5_wrap.c
  sunrpc: clean up sparse endianness warnings in gss_krb5_seal.c
  ...

30 files changed, 1124 insertions, 870 deletions

diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 9b431f44fad9..cbb1797149d5 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -210,8 +210,7 @@ static void bl_end_io_read(struct bio *bio, int err)
 			SetPageUptodate(bvec->bv_page);
 
 	if (err) {
-		struct nfs_pgio_data *rdata = par->data;
-		struct nfs_pgio_header *header = rdata->header;
+		struct nfs_pgio_header *header = par->data;
 
 		if (!header->pnfs_error)
 			header->pnfs_error = -EIO;
@@ -224,43 +223,44 @@ static void bl_end_io_read(struct bio *bio, int err)
 static void bl_read_cleanup(struct work_struct *work)
 {
 	struct rpc_task *task;
-	struct nfs_pgio_data *rdata;
+	struct nfs_pgio_header *hdr;
 	dprintk("%s enter\n", __func__);
 	task = container_of(work, struct rpc_task, u.tk_work);
-	rdata = container_of(task, struct nfs_pgio_data, task);
-	pnfs_ld_read_done(rdata);
+	hdr = container_of(task, struct nfs_pgio_header, task);
+	pnfs_ld_read_done(hdr);
 }
 
 static void
 bl_end_par_io_read(void *data, int unused)
 {
-	struct nfs_pgio_data *rdata = data;
+	struct nfs_pgio_header *hdr = data;
 
-	rdata->task.tk_status = rdata->header->pnfs_error;
-	INIT_WORK(&rdata->task.u.tk_work, bl_read_cleanup);
-	schedule_work(&rdata->task.u.tk_work);
+	hdr->task.tk_status = hdr->pnfs_error;
+	INIT_WORK(&hdr->task.u.tk_work, bl_read_cleanup);
+	schedule_work(&hdr->task.u.tk_work);
 }
 
 static enum pnfs_try_status
-bl_read_pagelist(struct nfs_pgio_data *rdata)
+bl_read_pagelist(struct nfs_pgio_header *hdr)
 {
-	struct nfs_pgio_header *header = rdata->header;
+	struct nfs_pgio_header *header = hdr;
 	int i, hole;
 	struct bio *bio = NULL;
 	struct pnfs_block_extent *be = NULL, *cow_read = NULL;
 	sector_t isect, extent_length = 0;
 	struct parallel_io *par;
-	loff_t f_offset = rdata->args.offset;
-	size_t bytes_left = rdata->args.count;
+	loff_t f_offset = hdr->args.offset;
+	size_t bytes_left = hdr->args.count;
 	unsigned int pg_offset, pg_len;
-	struct page **pages = rdata->args.pages;
-	int pg_index = rdata->args.pgbase >> PAGE_CACHE_SHIFT;
+	struct page **pages = hdr->args.pages;
+	int pg_index = hdr->args.pgbase >> PAGE_CACHE_SHIFT;
 	const bool is_dio = (header->dreq != NULL);
 
 	dprintk("%s enter nr_pages %u offset %lld count %u\n", __func__,
-	       rdata->pages.npages, f_offset, (unsigned int)rdata->args.count);
+		hdr->page_array.npages, f_offset,
+		(unsigned int)hdr->args.count);
 
-	par = alloc_parallel(rdata);
+	par = alloc_parallel(hdr);
 	if (!par)
 		goto use_mds;
 	par->pnfs_callback = bl_end_par_io_read;
@@ -268,7 +268,7 @@ bl_read_pagelist(struct nfs_pgio_data *rdata)
 
 	isect = (sector_t) (f_offset >> SECTOR_SHIFT);
 	/* Code assumes extents are page-aligned */
-	for (i = pg_index; i < rdata->pages.npages; i++) {
+	for (i = pg_index; i < hdr->page_array.npages; i++) {
 		if (!extent_length) {
 			/* We've used up the previous extent */
 			bl_put_extent(be);
@@ -317,7 +317,8 @@ bl_read_pagelist(struct nfs_pgio_data *rdata)
 			struct pnfs_block_extent *be_read;
 
 			be_read = (hole && cow_read) ? cow_read : be;
-			bio = do_add_page_to_bio(bio, rdata->pages.npages - i,
+			bio = do_add_page_to_bio(bio,
+						 hdr->page_array.npages - i,
 						 READ,
 						 isect, pages[i], be_read,
 						 bl_end_io_read, par,
@@ -332,10 +333,10 @@ bl_read_pagelist(struct nfs_pgio_data *rdata)
 		extent_length -= PAGE_CACHE_SECTORS;
 	}
 	if ((isect << SECTOR_SHIFT) >= header->inode->i_size) {
-		rdata->res.eof = 1;
-		rdata->res.count = header->inode->i_size - rdata->args.offset;
+		hdr->res.eof = 1;
+		hdr->res.count = header->inode->i_size - hdr->args.offset;
 	} else {
-		rdata->res.count = (isect << SECTOR_SHIFT) - rdata->args.offset;
+		hdr->res.count = (isect << SECTOR_SHIFT) - hdr->args.offset;
 	}
 out:
 	bl_put_extent(be);
@@ -390,8 +391,7 @@ static void bl_end_io_write_zero(struct bio *bio, int err)
 	}
 
 	if (unlikely(err)) {
-		struct nfs_pgio_data *data = par->data;
-		struct nfs_pgio_header *header = data->header;
+		struct nfs_pgio_header *header = par->data;
 
 		if (!header->pnfs_error)
 			header->pnfs_error = -EIO;
@@ -405,8 +405,7 @@ static void bl_end_io_write(struct bio *bio, int err)
 {
 	struct parallel_io *par = bio->bi_private;
 	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
-	struct nfs_pgio_data *data = par->data;
-	struct nfs_pgio_header *header = data->header;
+	struct nfs_pgio_header *header = par->data;
 
 	if (!uptodate) {
 		if (!header->pnfs_error)
@@ -423,32 +422,32 @@ static void bl_end_io_write(struct bio *bio, int err)
 static void bl_write_cleanup(struct work_struct *work)
 {
 	struct rpc_task *task;
-	struct nfs_pgio_data *wdata;
+	struct nfs_pgio_header *hdr;
 	dprintk("%s enter\n", __func__);
 	task = container_of(work, struct rpc_task, u.tk_work);
-	wdata = container_of(task, struct nfs_pgio_data, task);
-	if (likely(!wdata->header->pnfs_error)) {
+	hdr = container_of(task, struct nfs_pgio_header, task);
+	if (likely(!hdr->pnfs_error)) {
 		/* Marks for LAYOUTCOMMIT */
-		mark_extents_written(BLK_LSEG2EXT(wdata->header->lseg),
-				     wdata->args.offset, wdata->args.count);
+		mark_extents_written(BLK_LSEG2EXT(hdr->lseg),
+				     hdr->args.offset, hdr->args.count);
 	}
-	pnfs_ld_write_done(wdata);
+	pnfs_ld_write_done(hdr);
 }
 
 /* Called when last of bios associated with a bl_write_pagelist call finishes */
 static void bl_end_par_io_write(void *data, int num_se)
 {
-	struct nfs_pgio_data *wdata = data;
+	struct nfs_pgio_header *hdr = data;
 
-	if (unlikely(wdata->header->pnfs_error)) {
-		bl_free_short_extents(&BLK_LSEG2EXT(wdata->header->lseg)->bl_inval,
+	if (unlikely(hdr->pnfs_error)) {
+		bl_free_short_extents(&BLK_LSEG2EXT(hdr->lseg)->bl_inval,
 					num_se);
 	}
 
-	wdata->task.tk_status = wdata->header->pnfs_error;
-	wdata->verf.committed = NFS_FILE_SYNC;
-	INIT_WORK(&wdata->task.u.tk_work, bl_write_cleanup);
-	schedule_work(&wdata->task.u.tk_work);
+	hdr->task.tk_status = hdr->pnfs_error;
+	hdr->verf.committed = NFS_FILE_SYNC;
+	INIT_WORK(&hdr->task.u.tk_work, bl_write_cleanup);
+	schedule_work(&hdr->task.u.tk_work);
 }
 
 /* FIXME STUB - mark intersection of layout and page as bad, so is not
@@ -673,18 +672,17 @@ check_page:
 }
 
 static enum pnfs_try_status
-bl_write_pagelist(struct nfs_pgio_data *wdata, int sync)
+bl_write_pagelist(struct nfs_pgio_header *header, int sync)
 {
-	struct nfs_pgio_header *header = wdata->header;
 	int i, ret, npg_zero, pg_index, last = 0;
 	struct bio *bio = NULL;
 	struct pnfs_block_extent *be = NULL, *cow_read = NULL;
 	sector_t isect, last_isect = 0, extent_length = 0;
 	struct parallel_io *par = NULL;
-	loff_t offset = wdata->args.offset;
-	size_t count = wdata->args.count;
+	loff_t offset = header->args.offset;
+	size_t count = header->args.count;
 	unsigned int pg_offset, pg_len, saved_len;
-	struct page **pages = wdata->args.pages;
+	struct page **pages = header->args.pages;
 	struct page *page;
 	pgoff_t index;
 	u64 temp;
@@ -699,11 +697,11 @@ bl_write_pagelist(struct nfs_pgio_data *wdata, int sync)
 		dprintk("pnfsblock nonblock aligned DIO writes. Resend MDS\n");
 		goto out_mds;
 	}
-	/* At this point, wdata->pages is a (sequential) list of nfs_pages.
+	/* At this point, header->page_aray is a (sequential) list of nfs_pages.
 	 * We want to write each, and if there is an error set pnfs_error
 	 * to have it redone using nfs.
 	 */
-	par = alloc_parallel(wdata);
+	par = alloc_parallel(header);
 	if (!par)
 		goto out_mds;
 	par->pnfs_callback = bl_end_par_io_write;
@@ -790,8 +788,8 @@ next_page:
 	bio = bl_submit_bio(WRITE, bio);
 
 	/* Middle pages */
-	pg_index = wdata->args.pgbase >> PAGE_CACHE_SHIFT;
-	for (i = pg_index; i < wdata->pages.npages; i++) {
+	pg_index = header->args.pgbase >> PAGE_CACHE_SHIFT;
+	for (i = pg_index; i < header->page_array.npages; i++) {
 		if (!extent_length) {
 			/* We've used up the previous extent */
 			bl_put_extent(be);
@@ -862,7 +860,8 @@ next_page:
 		}
 
 
-		bio = do_add_page_to_bio(bio, wdata->pages.npages - i, WRITE,
+		bio = do_add_page_to_bio(bio, header->page_array.npages - i,
+					 WRITE,
 					 isect, pages[i], be,
 					 bl_end_io_write, par,
 					 pg_offset, pg_len);
@@ -890,7 +889,7 @@ next_page:
 	}
 
 write_done:
-	wdata->res.count = wdata->args.count;
+	header->res.count = header->args.count;
 out:
 	bl_put_extent(be);
 	bl_put_extent(cow_read);
@@ -1063,7 +1062,7 @@ nfs4_blk_get_deviceinfo(struct nfs_server *server, const struct nfs_fh *fh,
 		return ERR_PTR(-ENOMEM);
 	}
 
-	pages = kzalloc(max_pages * sizeof(struct page *), GFP_NOFS);
+	pages = kcalloc(max_pages, sizeof(struct page *), GFP_NOFS);
 	if (pages == NULL) {
 		kfree(dev);
 		return ERR_PTR(-ENOMEM);
diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index 073b4cf67ed9..54de482143cc 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -428,6 +428,18 @@ check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
 	if (p == NULL)
 		return 0;
 
+	/*
+	 * Did we get the acceptor from userland during the SETCLIENID
+	 * negotiation?
+	 */
+	if (clp->cl_acceptor)
+		return !strcmp(p, clp->cl_acceptor);
+
+	/*
+	 * Otherwise try to verify it using the cl_hostname. Note that this
+	 * doesn't work if a non-canonical hostname was used in the devname.
+	 */
+
 	/* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */
 
 	if (memcmp(p, "nfs@", 4) != 0)
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 180d1ec9c32e..1c5ff6d58385 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -110,8 +110,8 @@ struct nfs_subversion *get_nfs_version(unsigned int version)
 		mutex_unlock(&nfs_version_mutex);
 	}
 
-	if (!IS_ERR(nfs))
-		try_module_get(nfs->owner);
+	if (!IS_ERR(nfs) && !try_module_get(nfs->owner))
+		return ERR_PTR(-EAGAIN);
 	return nfs;
 }
 
@@ -158,7 +158,8 @@ struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init)
 		goto error_0;
 
 	clp->cl_nfs_mod = cl_init->nfs_mod;
-	try_module_get(clp->cl_nfs_mod->owner);
+	if (!try_module_get(clp->cl_nfs_mod->owner))
+		goto error_dealloc;
 
 	clp->rpc_ops = clp->cl_nfs_mod->rpc_ops;
 
@@ -190,6 +191,7 @@ struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init)
 
 error_cleanup:
 	put_nfs_version(clp->cl_nfs_mod);
+error_dealloc:
 	kfree(clp);
 error_0:
 	return ERR_PTR(err);
@@ -252,6 +254,7 @@ void nfs_free_client(struct nfs_client *clp)
 	put_net(clp->cl_net);
 	put_nfs_version(clp->cl_nfs_mod);
 	kfree(clp->cl_hostname);
+	kfree(clp->cl_acceptor);
 	kfree(clp);
 
 	dprintk("<-- nfs_free_client()\n");
@@ -482,8 +485,13 @@ nfs_get_client(const struct nfs_client_initdata *cl_init,
 	struct nfs_net *nn = net_generic(cl_init->net, nfs_net_id);
 	const struct nfs_rpc_ops *rpc_ops = cl_init->nfs_mod->rpc_ops;
 
+	if (cl_init->hostname == NULL) {
+		WARN_ON(1);
+		return NULL;
+	}
+
 	dprintk("--> nfs_get_client(%s,v%u)\n",
-		cl_init->hostname ?: "", rpc_ops->version);
+		cl_init->hostname, rpc_ops->version);
 
 	/* see if the client already exists */
 	do {
@@ -510,7 +518,7 @@ nfs_get_client(const struct nfs_client_initdata *cl_init,
 	} while (!IS_ERR(new));
 
 	dprintk("<-- nfs_get_client() Failed to find %s (%ld)\n",
-		cl_init->hostname ?: "", PTR_ERR(new));
+		cl_init->hostname, PTR_ERR(new));
 	return new;
 }
 EXPORT_SYMBOL_GPL(nfs_get_client);
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 5d8ccecf5f5c..5853f53db732 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -41,14 +41,8 @@ void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
 	set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
 }
 
-/**
- * nfs_have_delegation - check if inode has a delegation
- * @inode: inode to check
- * @flags: delegation types to check for
- *
- * Returns one if inode has the indicated delegation, otherwise zero.
- */
-int nfs4_have_delegation(struct inode *inode, fmode_t flags)
+static int
+nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
 {
 	struct nfs_delegation *delegation;
 	int ret = 0;
@@ -58,12 +52,34 @@ int nfs4_have_delegation(struct inode *inode, fmode_t flags)
 	delegation = rcu_dereference(NFS_I(inode)->delegation);
 	if (delegation != NULL && (delegation->type & flags) == flags &&
 	    !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
-		nfs_mark_delegation_referenced(delegation);
+		if (mark)
+			nfs_mark_delegation_referenced(delegation);
 		ret = 1;
 	}
 	rcu_read_unlock();
 	return ret;
 }
+/**
+ * nfs_have_delegation - check if inode has a delegation, mark it
+ * NFS_DELEGATION_REFERENCED if there is one.
+ * @inode: inode to check
+ * @flags: delegation types to check for
+ *
+ * Returns one if inode has the indicated delegation, otherwise zero.
+ */
+int nfs4_have_delegation(struct inode *inode, fmode_t flags)
+{
+	return nfs4_do_check_delegation(inode, flags, true);
+}
+
+/*
+ * nfs4_check_delegation - check if inode has a delegation, do not mark
+ * NFS_DELEGATION_REFERENCED if it has one.
+ */
+int nfs4_check_delegation(struct inode *inode, fmode_t flags)
+{
+	return nfs4_do_check_delegation(inode, flags, false);
+}
 
 static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_state *state, const nfs4_stateid *stateid)
 {
diff --git a/fs/nfs/delegation.h b/fs/nfs/delegation.h
index 9a79c7a99d6d..5c1cce39297f 100644
--- a/fs/nfs/delegation.h
+++ b/fs/nfs/delegation.h
@@ -59,6 +59,7 @@ bool nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode, fmode_
 
 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation);
 int nfs4_have_delegation(struct inode *inode, fmode_t flags);
+int nfs4_check_delegation(struct inode *inode, fmode_t flags);
 
 #endif
 
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 4a3d4ef76127..36d921f0c602 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -988,9 +988,13 @@ 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)
+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)
@@ -998,7 +1002,11 @@ static int nfs_check_verifier(struct inode *dir, struct dentry *dentry)
 	if (!nfs_verify_change_attribute(dir, dentry->d_time))
 		return 0;
 	/* Revalidate nfsi->cache_change_attribute before we declare a match */
-	if (nfs_revalidate_inode(NFS_SERVER(dir), dir) < 0)
+	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;
@@ -1042,6 +1050,8 @@ int nfs_lookup_verify_inode(struct inode *inode, unsigned int flags)
 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;
@@ -1054,6 +1064,9 @@ out_force:
  *
  * 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,
@@ -1064,7 +1077,7 @@ int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
 		return 0;
 	if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG)
 		return 1;
-	return !nfs_check_verifier(dir, dentry);
+	return !nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU);
 }
 
 /*
@@ -1088,21 +1101,30 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 	struct nfs4_label *label = NULL;
 	int error;
 
-	if (flags & LOOKUP_RCU)
-		return -ECHILD;
-
-	parent = dget_parent(dentry);
-	dir = parent->d_inode;
+	if (flags & LOOKUP_RCU) {
+		parent = ACCESS_ONCE(dentry->d_parent);
+		dir = ACCESS_ONCE(parent->d_inode);
+		if (!dir)
+			return -ECHILD;
+	} else {
+		parent = dget_parent(dentry);
+		dir = parent->d_inode;
+	}
 	nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE);
 	inode = dentry->d_inode;
 
 	if (!inode) {
-		if (nfs_neg_need_reval(dir, dentry, flags))
+		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;
@@ -1112,12 +1134,20 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 		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)) {
-		if (nfs_lookup_verify_inode(inode, flags))
+	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;
 
@@ -1153,13 +1183,18 @@ out_set_verifier:
 	/* Success: notify readdir to use READDIRPLUS */
 	nfs_advise_use_readdirplus(dir);
  out_valid_noent:
-	dput(parent);
+	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);
@@ -1185,6 +1220,7 @@ out_zap_parent:
 			__func__, dentry);
 	return 0;
 out_error:
+	WARN_ON(flags & LOOKUP_RCU);
 	nfs_free_fattr(fattr);
 	nfs_free_fhandle(fhandle);
 	nfs4_label_free(label);
@@ -1529,14 +1565,9 @@ EXPORT_SYMBOL_GPL(nfs_atomic_open);
 
 static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 {
-	struct dentry *parent = NULL;
 	struct inode *inode;
-	struct inode *dir;
 	int ret = 0;
 
-	if (flags & LOOKUP_RCU)
-		return -ECHILD;
-
 	if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY))
 		goto no_open;
 	if (d_mountpoint(dentry))
@@ -1545,34 +1576,47 @@ static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags)
 		goto no_open;
 
 	inode = dentry->d_inode;
-	parent = dget_parent(dentry);
-	dir = parent->d_inode;
 
 	/* 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 = ACCESS_ONCE(parent->d_inode);
+			if (!dir)
+				return -ECHILD;
+		} else {
+			parent = dget_parent(dentry);
+			dir = parent->d_inode;
+		}
 		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_dput;
+		goto no_open;
 	/* We cannot do exclusive creation on a positive dentry */
 	if (flags & LOOKUP_EXCL)
-		goto no_open_dput;
+		goto no_open;
 
 	/* Let f_op->open() actually open (and revalidate) the file */
 	ret = 1;
 
 out:
-	dput(parent);
 	return ret;
 
-no_open_dput:
-	dput(parent);
 no_open:
 	return nfs_lookup_revalidate(dentry, flags);
 }
@@ -2028,10 +2072,14 @@ 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(entry);
+	kfree_rcu(entry, rcu_head);
 	smp_mb__before_atomic();
 	atomic_long_dec(&nfs_access_nr_entries);
 	smp_mb__after_atomic();
@@ -2048,19 +2096,14 @@ static void nfs_access_free_list(struct list_head *head)
 	}
 }
 
-unsigned long
-nfs_access_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
+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;
-	int nr_to_scan = sc->nr_to_scan;
-	gfp_t gfp_mask = sc->gfp_mask;
 	long freed = 0;
 
-	if ((gfp_mask & GFP_KERNEL) != GFP_KERNEL)
-		return SHRINK_STOP;
-
 	spin_lock(&nfs_access_lru_lock);
 	list_for_each_entry_safe(nfsi, next, &nfs_access_lru_list, access_cache_inode_lru) {
 		struct inode *inode;
@@ -2094,11 +2137,39 @@ remove_lru_entry:
 }
 
 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;
@@ -2186,6 +2257,38 @@ out_zap:
 	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);
@@ -2229,6 +2332,11 @@ void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
 	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 */
@@ -2244,6 +2352,7 @@ void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
 					&nfs_access_lru_list);
 		spin_unlock(&nfs_access_lru_lock);
 	}
+	nfs_access_cache_enforce_limit();
 }
 EXPORT_SYMBOL_GPL(nfs_access_add_cache);
 
@@ -2267,10 +2376,16 @@ static int nfs_do_access(struct inode *inode, struct rpc_cred *cred, int mask)
 
 	trace_nfs_access_enter(inode);
 
-	status = nfs_access_get_cached(inode, cred, &cache);
+	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;
@@ -2321,9 +2436,6 @@ int nfs_permission(struct inode *inode, int mask)
 	struct rpc_cred *cred;
 	int res = 0;
 
-	if (mask & MAY_NOT_BLOCK)
-		return -ECHILD;
-
 	nfs_inc_stats(inode, NFSIOS_VFSACCESS);
 
 	if ((mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
@@ -2350,12 +2462,23 @@ force_lookup:
 	if (!NFS_PROTO(inode)->access)
 		goto out_notsup;
 
-	cred = rpc_lookup_cred();
-	if (!IS_ERR(cred)) {
-		res = nfs_do_access(inode, cred, mask);
-		put_rpccred(cred);
-	} else
+	/* 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);
+