Adding upstream version 4.19.249.upstream/4.19.249

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

1 files changed, 3110 insertions, 0 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
new file mode 100644
index 000000000..cfb1fe5df
--- /dev/null
+++ b/fs/nfs/pnfs.c
@@ -0,0 +1,3110 @@
+/*
+ *  pNFS functions to call and manage layout drivers.
+ *
+ *  Copyright (c) 2002 [year of first publication]
+ *  The Regents of the University of Michigan
+ *  All Rights Reserved
+ *
+ *  Dean Hildebrand <dhildebz@umich.edu>
+ *
+ *  Permission is granted to use, copy, create derivative works, and
+ *  redistribute this software and such derivative works for any purpose,
+ *  so long as the name of the University of Michigan is not used in
+ *  any advertising or publicity pertaining to the use or distribution
+ *  of this software without specific, written prior authorization. If
+ *  the above copyright notice or any other identification of the
+ *  University of Michigan is included in any copy of any portion of
+ *  this software, then the disclaimer below must also be included.
+ *
+ *  This software is provided as is, without representation or warranty
+ *  of any kind either express or implied, including without limitation
+ *  the implied warranties of merchantability, fitness for a particular
+ *  purpose, or noninfringement.  The Regents of the University of
+ *  Michigan shall not be liable for any damages, including special,
+ *  indirect, incidental, or consequential damages, with respect to any
+ *  claim arising out of or in connection with the use of the software,
+ *  even if it has been or is hereafter advised of the possibility of
+ *  such damages.
+ */
+
+#include <linux/nfs_fs.h>
+#include <linux/nfs_page.h>
+#include <linux/module.h>
+#include <linux/sort.h>
+#include "internal.h"
+#include "pnfs.h"
+#include "iostat.h"
+#include "nfs4trace.h"
+#include "delegation.h"
+#include "nfs42.h"
+#include "nfs4_fs.h"
+
+#define NFSDBG_FACILITY		NFSDBG_PNFS
+#define PNFS_LAYOUTGET_RETRY_TIMEOUT (120*HZ)
+
+/* Locking:
+ *
+ * pnfs_spinlock:
+ *      protects pnfs_modules_tbl.
+ */
+static DEFINE_SPINLOCK(pnfs_spinlock);
+
+/*
+ * pnfs_modules_tbl holds all pnfs modules
+ */
+static LIST_HEAD(pnfs_modules_tbl);
+
+static void pnfs_layoutreturn_before_put_layout_hdr(struct pnfs_layout_hdr *lo);
+static void pnfs_free_returned_lsegs(struct pnfs_layout_hdr *lo,
+		struct list_head *free_me,
+		const struct pnfs_layout_range *range,
+		u32 seq);
+static bool pnfs_lseg_dec_and_remove_zero(struct pnfs_layout_segment *lseg,
+		                struct list_head *tmp_list);
+
+/* Return the registered pnfs layout driver module matching given id */
+static struct pnfs_layoutdriver_type *
+find_pnfs_driver_locked(u32 id)
+{
+	struct pnfs_layoutdriver_type *local;
+
+	list_for_each_entry(local, &pnfs_modules_tbl, pnfs_tblid)
+		if (local->id == id)
+			goto out;
+	local = NULL;
+out:
+	dprintk("%s: Searching for id %u, found %p\n", __func__, id, local);
+	return local;
+}
+
+static struct pnfs_layoutdriver_type *
+find_pnfs_driver(u32 id)
+{
+	struct pnfs_layoutdriver_type *local;
+
+	spin_lock(&pnfs_spinlock);
+	local = find_pnfs_driver_locked(id);
+	if (local != NULL && !try_module_get(local->owner)) {
+		dprintk("%s: Could not grab reference on module\n", __func__);
+		local = NULL;
+	}
+	spin_unlock(&pnfs_spinlock);
+	return local;
+}
+
+const struct pnfs_layoutdriver_type *pnfs_find_layoutdriver(u32 id)
+{
+	return find_pnfs_driver(id);
+}
+
+void pnfs_put_layoutdriver(const struct pnfs_layoutdriver_type *ld)
+{
+	if (ld)
+		module_put(ld->owner);
+}
+
+void
+unset_pnfs_layoutdriver(struct nfs_server *nfss)
+{
+	if (nfss->pnfs_curr_ld) {
+		if (nfss->pnfs_curr_ld->clear_layoutdriver)
+			nfss->pnfs_curr_ld->clear_layoutdriver(nfss);
+		/* Decrement the MDS count. Purge the deviceid cache if zero */
+		if (atomic_dec_and_test(&nfss->nfs_client->cl_mds_count))
+			nfs4_deviceid_purge_client(nfss->nfs_client);
+		module_put(nfss->pnfs_curr_ld->owner);
+	}
+	nfss->pnfs_curr_ld = NULL;
+}
+
+/*
+ * When the server sends a list of layout types, we choose one in the order
+ * given in the list below.
+ *
+ * FIXME: should this list be configurable in some fashion? module param?
+ * 	  mount option? something else?
+ */
+static const u32 ld_prefs[] = {
+	LAYOUT_SCSI,
+	LAYOUT_BLOCK_VOLUME,
+	LAYOUT_OSD2_OBJECTS,
+	LAYOUT_FLEX_FILES,
+	LAYOUT_NFSV4_1_FILES,
+	0
+};
+
+static int
+ld_cmp(const void *e1, const void *e2)
+{
+	u32 ld1 = *((u32 *)e1);
+	u32 ld2 = *((u32 *)e2);
+	int i;
+
+	for (i = 0; ld_prefs[i] != 0; i++) {
+		if (ld1 == ld_prefs[i])
+			return -1;
+
+		if (ld2 == ld_prefs[i])
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * Try to set the server's pnfs module to the pnfs layout type specified by id.
+ * Currently only one pNFS layout driver per filesystem is supported.
+ *
+ * @ids array of layout types supported by MDS.
+ */
+void
+set_pnfs_layoutdriver(struct nfs_server *server, const struct nfs_fh *mntfh,
+		      struct nfs_fsinfo *fsinfo)
+{
+	struct pnfs_layoutdriver_type *ld_type = NULL;
+	u32 id;
+	int i;
+
+	if (fsinfo->nlayouttypes == 0)
+		goto out_no_driver;
+	if (!(server->nfs_client->cl_exchange_flags &
+		 (EXCHGID4_FLAG_USE_NON_PNFS | EXCHGID4_FLAG_USE_PNFS_MDS))) {
+		printk(KERN_ERR "NFS: %s: cl_exchange_flags 0x%x\n",
+			__func__, server->nfs_client->cl_exchange_flags);
+		goto out_no_driver;
+	}
+
+	sort(fsinfo->layouttype, fsinfo->nlayouttypes,
+		sizeof(*fsinfo->layouttype), ld_cmp, NULL);
+
+	for (i = 0; i < fsinfo->nlayouttypes; i++) {
+		id = fsinfo->layouttype[i];
+		ld_type = find_pnfs_driver(id);
+		if (!ld_type) {
+			request_module("%s-%u", LAYOUT_NFSV4_1_MODULE_PREFIX,
+					id);
+			ld_type = find_pnfs_driver(id);
+		}
+		if (ld_type)
+			break;
+	}
+
+	if (!ld_type) {
+		dprintk("%s: No pNFS module found!\n", __func__);
+		goto out_no_driver;
+	}
+
+	server->pnfs_curr_ld = ld_type;
+	if (ld_type->set_layoutdriver
+	    && ld_type->set_layoutdriver(server, mntfh)) {
+		printk(KERN_ERR "NFS: %s: Error initializing pNFS layout "
+			"driver %u.\n", __func__, id);
+		module_put(ld_type->owner);
+		goto out_no_driver;
+	}
+	/* Bump the MDS count */
+	atomic_inc(&server->nfs_client->cl_mds_count);
+
+	dprintk("%s: pNFS module for %u set\n", __func__, id);
+	return;
+
+out_no_driver:
+	dprintk("%s: Using NFSv4 I/O\n", __func__);
+	server->pnfs_curr_ld = NULL;
+}
+
+int
+pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
+{
+	int status = -EINVAL;
+	struct pnfs_layoutdriver_type *tmp;
+
+	if (ld_type->id == 0) {
+		printk(KERN_ERR "NFS: %s id 0 is reserved\n", __func__);
+		return status;
+	}
+	if (!ld_type->alloc_lseg || !ld_type->free_lseg) {
+		printk(KERN_ERR "NFS: %s Layout driver must provide "
+		       "alloc_lseg and free_lseg.\n", __func__);
+		return status;
+	}
+
+	spin_lock(&pnfs_spinlock);
+	tmp = find_pnfs_driver_locked(ld_type->id);
+	if (!tmp) {
+		list_add(&ld_type->pnfs_tblid, &pnfs_modules_tbl);
+		status = 0;
+		dprintk("%s Registering id:%u name:%s\n", __func__, ld_type->id,
+			ld_type->name);
+	} else {
+		printk(KERN_ERR "NFS: %s Module with id %d already loaded!\n",
+			__func__, ld_type->id);
+	}
+	spin_unlock(&pnfs_spinlock);
+
+	return status;
+}
+EXPORT_SYMBOL_GPL(pnfs_register_layoutdriver);
+
+void
+pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
+{
+	dprintk("%s Deregistering id:%u\n", __func__, ld_type->id);
+	spin_lock(&pnfs_spinlock);
+	list_del(&ld_type->pnfs_tblid);
+	spin_unlock(&pnfs_spinlock);
+}
+EXPORT_SYMBOL_GPL(pnfs_unregister_layoutdriver);
+
+/*
+ * pNFS client layout cache
+ */
+
+/* Need to hold i_lock if caller does not already hold reference */
+void
+pnfs_get_layout_hdr(struct pnfs_layout_hdr *lo)
+{
+	refcount_inc(&lo->plh_refcount);
+}
+
+static struct pnfs_layout_hdr *
+pnfs_alloc_layout_hdr(struct inode *ino, gfp_t gfp_flags)
+{
+	struct pnfs_layoutdriver_type *ld = NFS_SERVER(ino)->pnfs_curr_ld;
+	return ld->alloc_layout_hdr(ino, gfp_flags);
+}
+
+static void
+pnfs_free_layout_hdr(struct pnfs_layout_hdr *lo)
+{
+	struct nfs_server *server = NFS_SERVER(lo->plh_inode);
+	struct pnfs_layoutdriver_type *ld = server->pnfs_curr_ld;
+
+	if (!list_empty(&lo->plh_layouts)) {
+		struct nfs_client *clp = server->nfs_client;
+
+		spin_lock(&clp->cl_lock);
+		list_del_init(&lo->plh_layouts);
+		spin_unlock(&clp->cl_lock);
+	}
+	put_rpccred(lo->plh_lc_cred);
+	return ld->free_layout_hdr(lo);
+}
+
+static void
+pnfs_detach_layout_hdr(struct pnfs_layout_hdr *lo)
+{
+	struct nfs_inode *nfsi = NFS_I(lo->plh_inode);
+	dprintk("%s: freeing layout cache %p\n", __func__, lo);
+	nfsi->layout = NULL;
+	/* Reset MDS Threshold I/O counters */
+	nfsi->write_io = 0;
+	nfsi->read_io = 0;
+}
+
+void
+pnfs_put_layout_hdr(struct pnfs_layout_hdr *lo)
+{
+	struct inode *inode;
+	unsigned long i_state;
+
+	if (!lo)
+		return;
+	inode = lo->plh_inode;
+	pnfs_layoutreturn_before_put_layout_hdr(lo);
+
+	if (refcount_dec_and_lock(&lo->plh_refcount, &inode->i_lock)) {
+		if (!list_empty(&lo->plh_segs))
+			WARN_ONCE(1, "NFS: BUG unfreed layout segments.\n");
+		pnfs_detach_layout_hdr(lo);
+		i_state = inode->i_state;
+		spin_unlock(&inode->i_lock);
+		pnfs_free_layout_hdr(lo);
+		/* Notify pnfs_destroy_layout_final() that we're done */
+		if (i_state & (I_FREEING | I_CLEAR))
+			wake_up_var(lo);
+	}
+}
+
+static void
+pnfs_set_plh_return_info(struct pnfs_layout_hdr *lo, enum pnfs_iomode iomode,
+			 u32 seq)
+{
+	if (lo->plh_return_iomode != 0 && lo->plh_return_iomode != iomode)
+		iomode = IOMODE_ANY;
+	lo->plh_return_iomode = iomode;
+	set_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags);
+	if (seq != 0) {
+		WARN_ON_ONCE(lo->plh_return_seq != 0 && lo->plh_return_seq != seq);
+		lo->plh_return_seq = seq;
+	}
+}
+
+static void
+pnfs_clear_layoutreturn_info(struct pnfs_layout_hdr *lo)
+{
+	struct pnfs_layout_segment *lseg;
+	lo->plh_return_iomode = 0;
+	lo->plh_return_seq = 0;
+	clear_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags);
+	list_for_each_entry(lseg, &lo->plh_segs, pls_list) {
+		if (!test_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags))
+			continue;
+		pnfs_set_plh_return_info(lo, lseg->pls_range.iomode, 0);
+	}
+}
+
+static void pnfs_clear_layoutreturn_waitbit(struct pnfs_layout_hdr *lo)
+{
+	clear_bit_unlock(NFS_LAYOUT_RETURN, &lo->plh_flags);
+	clear_bit(NFS_LAYOUT_RETURN_LOCK, &lo->plh_flags);
+	smp_mb__after_atomic();
+	wake_up_bit(&lo->plh_flags, NFS_LAYOUT_RETURN);
+	rpc_wake_up(&NFS_SERVER(lo->plh_inode)->roc_rpcwaitq);
+}
+
+static void
+pnfs_clear_lseg_state(struct pnfs_layout_segment *lseg,
+		struct list_head *free_me)
+{
+	clear_bit(NFS_LSEG_ROC, &lseg->pls_flags);
+	clear_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags);
+	if (test_and_clear_bit(NFS_LSEG_VALID, &lseg->pls_flags))
+		pnfs_lseg_dec_and_remove_zero(lseg, free_me);
+	if (test_and_clear_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags))
+		pnfs_lseg_dec_and_remove_zero(lseg, free_me);
+}
+
+/*
+ * Update the seqid of a layout stateid
+ */
+bool nfs4_layoutreturn_refresh_stateid(nfs4_stateid *dst,
+		struct pnfs_layout_range *dst_range,
+		struct inode *inode)
+{
+	struct pnfs_layout_hdr *lo;
+	struct pnfs_layout_range range = {
+		.iomode = IOMODE_ANY,
+		.offset = 0,
+		.length = NFS4_MAX_UINT64,
+	};
+	bool ret = false;
+	LIST_HEAD(head);
+	int err;
+
+	spin_lock(&inode->i_lock);
+	lo = NFS_I(inode)->layout;
+	if (lo && nfs4_stateid_match_other(dst, &lo->plh_stateid)) {
+		err = pnfs_mark_matching_lsegs_return(lo, &head, &range, 0);
+		if (err != -EBUSY) {
+			dst->seqid = lo->plh_stateid.seqid;
+			*dst_range = range;
+			ret = true;
+		}
+	}
+	spin_unlock(&inode->i_lock);
+	pnfs_free_lseg_list(&head);
+	return ret;
+}
+
+/*
+ * Mark a pnfs_layout_hdr and all associated layout segments as invalid
+ *
+ * In order to continue using the pnfs_layout_hdr, a full recovery
+ * is required.
+ * Note that caller must hold inode->i_lock.
+ */
+int
+pnfs_mark_layout_stateid_invalid(struct pnfs_layout_hdr *lo,
+		struct list_head *lseg_list)
+{
+	struct pnfs_layout_range range = {
+		.iomode = IOMODE_ANY,
+		.offset = 0,
+		.length = NFS4_MAX_UINT64,
+	};
+	struct pnfs_layout_segment *lseg, *next;
+
+	set_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
+	list_for_each_entry_safe(lseg, next, &lo->plh_segs, pls_list)
+		pnfs_clear_lseg_state(lseg, lseg_list);
+	pnfs_clear_layoutreturn_info(lo);
+	pnfs_free_returned_lsegs(lo, lseg_list, &range, 0);
+	if (test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags) &&
+	    !test_and_set_bit(NFS_LAYOUT_RETURN_LOCK, &lo->plh_flags))
+		pnfs_clear_layoutreturn_waitbit(lo);
+	return !list_empty(&lo->plh_segs);
+}
+
+static int
+pnfs_iomode_to_fail_bit(u32 iomode)
+{
+	return iomode == IOMODE_RW ?
+		NFS_LAYOUT_RW_FAILED : NFS_LAYOUT_RO_FAILED;
+}
+
+static void
+pnfs_layout_set_fail_bit(struct pnfs_layout_hdr *lo, int fail_bit)
+{
+	lo->plh_retry_timestamp = jiffies;
+	if (!test_and_set_bit(fail_bit, &lo->plh_flags))
+		refcount_inc(&lo->plh_refcount);
+}
+
+static void
+pnfs_layout_clear_fail_bit(struct pnfs_layout_hdr *lo, int fail_bit)
+{
+	if (test_and_clear_bit(fail_bit, &lo->plh_flags))
+		refcount_dec(&lo->plh_refcount);
+}
+
+static void
+pnfs_layout_io_set_failed(struct pnfs_layout_hdr *lo, u32 iomode)
+{
+	struct inode *inode = lo->plh_inode;
+	struct pnfs_layout_range range = {
+		.iomode = iomode,
+		.offset = 0,
+		.length = NFS4_MAX_UINT64,
+	};
+	LIST_HEAD(head);
+
+	spin_lock(&inode->i_lock);
+	pnfs_layout_set_fail_bit(lo, pnfs_iomode_to_fail_bit(iomode));
+	pnfs_mark_matching_lsegs_invalid(lo, &head, &range, 0);
+	spin_unlock(&inode->i_lock);
+	pnfs_free_lseg_list(&head);
+	dprintk("%s Setting layout IOMODE_%s fail bit\n", __func__,
+			iomode == IOMODE_RW ?  "RW" : "READ");
+}
+
+static bool
+pnfs_layout_io_test_failed(struct pnfs_layout_hdr *lo, u32 iomode)
+{
+	unsigned long start, end;
+	int fail_bit = pnfs_iomode_to_fail_bit(iomode);
+
+	if (test_bit(fail_bit, &lo->plh_flags) == 0)
+		return false;
+	end = jiffies;
+	start = end - PNFS_LAYOUTGET_RETRY_TIMEOUT;
+	if (!time_in_range(lo->plh_retry_timestamp, start, end)) {
+		/* It is time to retry the failed layoutgets */
+		pnfs_layout_clear_fail_bit(lo, fail_bit);
+		return false;
+	}
+	return true;
+}
+
+static void
+pnfs_init_lseg(struct pnfs_layout_hdr *lo, struct pnfs_layout_segment *lseg,
+		const struct pnfs_layout_range *range,
+		const nfs4_stateid *stateid)
+{
+	INIT_LIST_HEAD(&lseg->pls_list);
+	INIT_LIST_HEAD(&lseg->pls_lc_list);
+	refcount_set(&lseg->pls_refcount, 1);
+	set_bit(NFS_LSEG_VALID, &lseg->pls_flags);
+	lseg->pls_layout = lo;
+	lseg->pls_range = *range;
+	lseg->pls_seq = be32_to_cpu(stateid->seqid);
+}
+
+static void pnfs_free_lseg(struct pnfs_layout_segment *lseg)
+{
+	if (lseg != NULL) {
+		struct inode *inode = lseg->pls_layout->plh_inode;
+		NFS_SERVER(inode)->pnfs_curr_ld->free_lseg(lseg);
+	}
+}
+
+static void
+pnfs_layout_remove_lseg(struct pnfs_layout_hdr *lo,
+		struct pnfs_layout_segment *lseg)
+{
+	WARN_ON(test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
+	list_del_init(&lseg->pls_list);
+	/* Matched by pnfs_get_layout_hdr in pnfs_layout_insert_lseg */
+	refcount_dec(&lo->plh_refcount);
+	if (test_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags))
+		return;
+	if (list_empty(&lo->plh_segs) &&
+	    !test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags) &&
+	    !test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags)) {
+		if (atomic_read(&lo->plh_outstanding) == 0)
+			set_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
+		clear_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags);
+	}
+}
+
+static bool
+pnfs_cache_lseg_for_layoutreturn(struct pnfs_layout_hdr *lo,
+		struct pnfs_layout_segment *lseg)
+{
+	if (test_and_clear_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags) &&
+	    pnfs_layout_is_valid(lo)) {
+		pnfs_set_plh_return_info(lo, lseg->pls_range.iomode, 0);
+		list_move_tail(&lseg->pls_list, &lo->plh_return_segs);
+		return true;
+	}
+	return false;
+}
+
+void
+pnfs_put_lseg(struct pnfs_layout_segment *lseg)
+{
+	struct pnfs_layout_hdr *lo;
+	struct inode *inode;
+
+	if (!lseg)
+		return;
+
+	dprintk("%s: lseg %p ref %d valid %d\n", __func__, lseg,
+		refcount_read(&lseg->pls_refcount),
+		test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
+
+	lo = lseg->pls_layout;
+	inode = lo->plh_inode;
+
+	if (refcount_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) {
+		if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags)) {
+			spin_unlock(&inode->i_lock);
+			return;
+		}
+		pnfs_get_layout_hdr(lo);
+		pnfs_layout_remove_lseg(lo, lseg);
+		if (pnfs_cache_lseg_for_layoutreturn(lo, lseg))
+			lseg = NULL;
+		spin_unlock(&inode->i_lock);
+		pnfs_free_lseg(lseg);
+		pnfs_put_layout_hdr(lo);
+	}
+}
+EXPORT_SYMBOL_GPL(pnfs_put_lseg);
+
+/*
+ * is l2 fully contained in l1?
+ *   start1                             end1
+ *   [----------------------------------)
+ *           start2           end2
+ *           [----------------)
+ */
+static bool
+pnfs_lseg_range_contained(const struct pnfs_layout_range *l1,
+		 const struct pnfs_layout_range *l2)
+{
+	u64 start1 = l1->offset;
+	u64 end1 = pnfs_end_offset(start1, l1->length);
+	u64 start2 = l2->offset;
+	u64 end2 = pnfs_end_offset(start2, l2->length);
+
+	return (start1 <= start2) && (end1 >= end2);
+}
+
+static bool pnfs_lseg_dec_and_remove_zero(struct pnfs_layout_segment *lseg,
+		struct list_head *tmp_list)
+{
+	if (!refcount_dec_and_test(&lseg->pls_refcount))
+		return false;
+	pnfs_layout_remove_lseg(lseg->pls_layout, lseg);
+	list_add(&lseg->pls_list, tmp_list);
+	return true;
+}
+
+/* Returns 1 if lseg is removed from list, 0 otherwise */
+static int mark_lseg_invalid(struct pnfs_layout_segment *lseg,
+			     struct list_head *tmp_list)
+{
+	int rv = 0;
+
+	if (test_and_clear_bit(NFS_LSEG_VALID, &lseg->pls_flags)) {
+		/* Remove the reference keeping the lseg in the
+		 * list.  It will now be removed when all
+		 * outstanding io is finished.
+		 */
+		dprintk("%s: lseg %p ref %d\n", __func__, lseg,
+			refcount_read(&lseg->pls_refcount));
+		if (pnfs_lseg_dec_and_remove_zero(lseg, tmp_list))
+			rv = 1;
+	}
+	return rv;
+}
+
+/*
+ * Compare 2 layout stateid sequence ids, to see which is newer,
+ * taking into account wraparound issues.
+ */
+static bool pnfs_seqid_is_newer(u32 s1, u32 s2)
+{
+	return (s32)(s1 - s2) > 0;
+}
+
+static bool
+pnfs_should_free_range(const struct pnfs_layout_range *lseg_range,
+		 const struct pnfs_layout_range *recall_range)
+{
+	return (recall_range->iomode == IOMODE_ANY ||
+		lseg_range->iomode == recall_range->iomode) &&
+	       pnfs_lseg_range_intersecting(lseg_range, recall_range);
+}
+
+static bool
+pnfs_match_lseg_recall(const struct pnfs_layout_segment *lseg,
+		const struct pnfs_layout_range *recall_range,
+		u32 seq)
+{
+	if (seq != 0 && pnfs_seqid_is_newer(lseg->pls_seq, seq))
+		return false;
+	if (recall_range == NULL)
+		return true;
+	return pnfs_should_free_range(&lseg->pls_range, recall_range);
+}
+
+/**
+ * pnfs_mark_matching_lsegs_invalid - tear down lsegs or mark them for later
+ * @lo: layout header containing the lsegs
+ * @tmp_list: list head where doomed lsegs should go
+ * @recall_range: optional recall range argument to match (may be NULL)
+ * @seq: only invalidate lsegs obtained prior to this sequence (may be 0)
+ *
+ * Walk the list of lsegs in the layout header, and tear down any that should
+ * be destroyed. If "recall_range" is specified then the segment must match
+ * that range. If "seq" is non-zero, then only match segments that were handed
+ * out at or before that sequence.
+ *
+ * Returns number of matching invalid lsegs remaining in list after scanning
+ * it and purging them.
+ */
+int
+pnfs_mark_matching_lsegs_invalid(struct pnfs_layout_hdr *lo,
+			    struct list_head *tmp_list,
+			    const struct pnfs_layout_range *recall_range,
+			    u32 seq)
+{
+	struct pnfs_layout_segment *lseg, *next;
+	int remaining = 0;
+
+	dprintk("%s:Begin lo %p\n", __func__, lo);
+
+	if (list_empty(&lo->plh_segs))
+		return 0;
+	list_for_each_entry_safe(lseg, next, &lo->plh_segs, pls_list)
+		if (pnfs_match_lseg_recall(lseg, recall_range, seq)) {
+			dprintk("%s: freeing lseg %p iomode %d seq %u "
+				"offset %llu length %llu\n", __func__,
+				lseg, lseg->pls_range.iomode, lseg->pls_seq,
+				lseg->pls_range.offset, lseg->pls_range.length);
+			if (!mark_lseg_invalid(lseg, tmp_list))
+				remaining++;
+		}
+	dprintk("%s:Return %i\n", __func__, remaining);
+	return remaining;
+}
+
+static void
+pnfs_free_returned_lsegs(struct pnfs_layout_hdr *lo,
+		struct list_head *free_me,
+		const struct pnfs_layout_range *range,
+		u32 seq)
+{
+	struct pnfs_layout_segment *lseg, *next;
+
+	list_for_each_entry_safe(lseg, next, &lo->plh_return_segs, pls_list) {
+		if (pnfs_match_lseg_recall(lseg, range, seq))
+			list_move_tail(&lseg->pls_list, free_me);
+	}
+}
+
+/* note free_me must contain lsegs from a single layout_hdr */
+void
+pnfs_free_lseg_list(struct list_head *free_me)
+{
+	struct pnfs_layout_segment *lseg, *tmp;
+
+	if (list_empty(free_me))
+		return;
+
+	list_for_each_entry_safe(lseg, tmp, free_me, pls_list) {
+		list_del(&lseg->pls_list);
+		pnfs_free_lseg(lseg);
+	}
+}
+
+static struct pnfs_layout_hdr *__pnfs_destroy_layout(struct nfs_inode *nfsi)
+{
+	struct pnfs_layout_hdr *lo;
+	LIST_HEAD(tmp_list);
+
+	spin_lock(&nfsi->vfs_inode.i_lock);
+	lo = nfsi->layout;
+	if (lo) {
+		pnfs_get_layout_hdr(lo);
+		pnfs_mark_layout_stateid_invalid(lo, &tmp_list);
+		pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RO_FAILED);
+		pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RW_FAILED);
+		spin_unlock(&nfsi->vfs_inode.i_lock);
+		pnfs_free_lseg_list(&tmp_list);
+		nfs_commit_inode(&nfsi->vfs_inode, 0);
+		pnfs_put_layout_hdr(lo);
+	} else
+		spin_unlock(&nfsi->vfs_inode.i_lock);
+	return lo;
+}
+
+void pnfs_destroy_layout(struct nfs_inode *nfsi)
+{
+	__pnfs_destroy_layout(nfsi);
+}
+EXPORT_SYMBOL_GPL(pnfs_destroy_layout);
+
+static bool pnfs_layout_removed(struct nfs_inode *nfsi,
+				struct pnfs_layout_hdr *lo)
+{
+	bool ret;
+
+	spin_lock(&nfsi->vfs_inode.i_lock);
+	ret = nfsi->layout != lo;
+	spin_unlock(&nfsi->vfs_inode.i_lock);
+	return ret;
+}
+
+void pnfs_destroy_layout_final(struct nfs_inode *nfsi)
+{
+	struct pnfs_layout_hdr *lo = __pnfs_destroy_layout(nfsi);
+
+	if (lo)
+		wait_var_event(lo, pnfs_layout_removed(nfsi, lo));
+}
+
+static bool
+pnfs_layout_add_bulk_destroy_list(struct inode *inode,
+		struct list_head *layout_list)
+{
+	struct pnfs_layout_hdr *lo;
+	bool ret = false;
+
+	spin_lock(&inode->i_lock);
+	lo = NFS_I(inode)->layout;
+	if (lo != NULL && list_empty(&lo->plh_bulk_destroy)) {
+		pnfs_get_layout_hdr(lo);
+		list_add(&lo->plh_bulk_destroy, layout_list);
+		ret = true;
+	}
+	spin_unlock(&inode->i_lock);
+	return ret;
+}
+
+/* Caller must hold rcu_read_lock and clp->cl_lock */
+static int
+pnfs_layout_bulk_destroy_byserver_locked(struct nfs_client *clp,
+		struct nfs_server *server,
+		struct list_head *layout_list)
+	__must_hold(&clp->cl_lock)
+	__must_hold(RCU)
+{
+	struct pnfs_layout_hdr *lo, *next;
+	struct inode *inode;
+
+	list_for_each_entry_safe(lo, next, &server->layouts, plh_layouts) {
+		if (test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags) ||
+		    test_bit(NFS_LAYOUT_INODE_FREEING, &lo->plh_flags) ||
+		    !list_empty(&lo->plh_bulk_destroy))
+			continue;
+		/* If the sb is being destroyed, just bail */
+		if (!nfs_sb_active(server->super))
+			break;
+		inode = igrab(lo->plh_inode);
+		if (inode != NULL) {
+			list_del_init(&lo->plh_layouts);
+			if (pnfs_layout_add_bulk_destroy_list(inode,
+						layout_list))
+				continue;
+			rcu_read_unlock();
+			spin_unlock(&clp->cl_lock);
+			iput(inode);
+		} else {
+			rcu_read_unlock();
+			spin_unlock(&clp->cl_lock);
+			set_bit(NFS_LAYOUT_INODE_FREEING, &lo->plh_flags);
+		}
+		nfs_sb_deactive(server->super);
+		spin_lock(&clp->cl_lock);
+		rcu_read_lock();
+		return -EAGAIN;
+	}
+	return 0;
+}
+
+static int
+pnfs_layout_free_bulk_destroy_list(struct list_head *layout_list,
+		bool is_bulk_recall)
+{
+	struct pnfs_layout_hdr *lo;
+	struct inode *inode;
+	LIST_HEAD(lseg_list);
+	int ret = 0;
+
+	while (!list_empty(layout_list)) {
+		lo = list_entry(layout_list->next, struct pnfs_layout_hdr,
+				plh_bulk_destroy);
+		dprintk("%s freeing layout for inode %lu\n", __func__,
+			lo->plh_inode->i_ino);
+		inode = lo->plh_inode;
+
+		pnfs_layoutcommit_inode(inode, false);
+
+		spin_lock(&inode->i_lock);
+		list_del_init(&lo->plh_bulk_destroy);
+		if (pnfs_mark_layout_stateid_invalid(lo, &lseg_list)) {
+			if (is_bulk_recall)
+				set_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags);
+			ret = -EAGAIN;
+		}
+		spin_unlock(&inode->i_lock);
+		pnfs_free_lseg_list(&lseg_list);
+		/* Free all lsegs that are attached to commit buckets */
+		nfs_commit_inode(inode, 0);
+		pnfs_put_layout_hdr(lo);
+		nfs_iput_and_deactive(inode);
+	}
+	return ret;
+}
+
+int
+pnfs_destroy_layouts_byfsid(struct nfs_client *clp,
+		struct nfs_fsid *fsid,
+		bool is_recall)
+{
+	struct nfs_server *server;
+	LIST_HEAD(layout_list);
+
+	spin_lock(&clp->cl_lock);
+	rcu_read_lock();
+restart:
+	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+		if (memcmp(&server->fsid, fsid, sizeof(*fsid)) != 0)
+			continue;
+		if (pnfs_layout_bulk_destroy_byserver_locked(clp,
+				server,
+				&layout_list) != 0)
+			goto restart;
+	}
+	rcu_read_unlock();
+	spin_unlock(&clp->cl_lock);
+
+	if (list_empty(&layout_list))
+		return 0;
+	return pnfs_layout_free_bulk_destroy_list(&layout_list, is_recall);
+}
+
+int
+pnfs_destroy_layouts_byclid(struct nfs_client *clp,
+		bool is_recall)
+{
+	struct nfs_server *server;
+	LIST_HEAD(layout_list);
+
+	spin_lock(&clp->cl_lock);
+	rcu_read_lock();
+restart:
+	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+		if (pnfs_layout_bulk_destroy_byserver_locked(clp,
+					server,
+					&layout_list) != 0)
+			goto restart;
+	}
+	rcu_read_unlock();
+	spin_unlock(&clp->cl_lock);
+
+	if (list_empty(&layout_list))
+		return 0;
+	return pnfs_layout_free_bulk_destroy_list(&layout_list, is_recall);
+}
+
+/*
+ * Called by the state manger to remove all layouts established under an
+ * expired lease.
+ */
+void
+pnfs_destroy_all_layouts(struct nfs_client *clp)
+{
+	nfs4_deviceid_mark_client_invalid(clp);
+	nfs4_deviceid_purge_client(clp);
+
+	pnfs_destroy_layouts_byclid(clp, false);
+}
+
+/* update lo->plh_stateid with new if is more recent */
+void
+pnfs_set_layout_stateid(struct pnfs_layout_hdr *lo, const nfs4_stateid *new,
+			bool update_barrier)
+{
+	u32 oldseq, newseq, new_barrier = 0;
+
+	oldseq = be32_to_cpu(lo->plh_stateid.seqid);
+	newseq = be32_to_cpu(new->seqid);
+
+	if (!pnfs_layout_is_valid(lo)) {
+		nfs4_stateid_copy(&lo->plh_stateid, new);
+		lo->plh_barrier = newseq;
+		pnfs_clear_layoutreturn_info(lo);
+		clear_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
+		return;
+	}
+	if (pnfs_seqid_is_newer(newseq, oldseq)) {
+		nfs4_stateid_copy(&lo->plh_stateid, new);
+		/*
+		 * Because of wraparound, we want to keep the barrier
+		 * "close" to the current seqids.
+		 */
+		new_barrier = newseq - atomic_read(&lo->plh_outstanding);
+	}
+	if (update_barrier)
+		new_barrier = be32_to_cpu(new->seqid);
+	else if (new_barrier == 0)
+		return;
+	if (pnfs_seqid_is_newer(new_barrier, lo->plh_barrier))
+		lo->plh_barrier = new_barrier;
+}
+
+static bool
+pnfs_layout_stateid_blocked(const struct pnfs_layout_hdr *lo,
+		const nfs4_stateid *stateid)
+{
+	u32 seqid = be32_to_cpu(stateid->seqid);
+
+	return !pnfs_seqid_is_newer(seqid, lo->plh_barrier);
+}
+
+/* lget is set to 1 if called from inside send_layoutget call chain */
+static bool
+pnfs_layoutgets_blocked(const struct pnfs_layout_hdr *lo)
+{
+	return lo->plh_block_lgets ||
+		test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags);
+}
+
+static struct nfs_server *
+pnfs_find_server(struct inode *inode, struct nfs_open_context *ctx)
+{
+	struct nfs_server *server;
+
+	if (inode) {
+		server = NFS_SERVER(inode);
+	} else {
+		struct dentry *parent_dir = dget_parent(ctx->dentry);
+		server = NFS_SERVER(parent_dir->d_inode);
+		dput(parent_dir);
+	}
+	return server;
+}
+
+static void nfs4_free_pages(struct page **pages, size_t size)
+{
+	int i;
+
+	if (!pages)
+		return;
+
+	for (i = 0; i < size; i++) {
+		if (!pages[i])
+			break;
+		__free_page(pages[i]);
+	}
+	kfree(pages);
+}
+
+static struct page **nfs4_alloc_pages(size_t size, gfp_t gfp_flags)
+{
+	struct page **pages;
+	int i;
+
+	pages = kcalloc(size, sizeof(struct page *), gfp_flags);
+	if (!pages) {
+		dprintk("%s: can't alloc array of %zu pages\n", __func__, size);
+		return NULL;
+	}
+
+	for (i = 0; i < size; i++) {
+		pages[i] = alloc_page(gfp_flags);
+		if (!pages[i]) {
+			dprintk("%s: failed to allocate page\n", __func__);
+			nfs4_free_pages(pages, size);
+			return NULL;
+		}
+	}
+
+	return pages;
+}
+
+static struct nfs4_layoutget *
+pnfs_alloc_init_layoutget_args(struct inode *ino,
+	   struct nfs_open_context *ctx,
+	   const nfs4_stateid *stateid,
+	   const struct pnfs_layout_range *range,
+	   gfp_t gfp_flags)
+{
+	struct nfs_server *server = pnfs_find_server(ino, ctx);
+	size_t max_pages = max_response_pages(server);
+	struct nfs4_layoutget *lgp;
+
+	dprintk("--> %s\n", __func__);
+
+	lgp = kzalloc(sizeof(*lgp), gfp_flags);
+	if (lgp == NULL)
+		return NULL;
+
+	lgp->args.layout.pages = nfs4_alloc_pages(max_pages, gfp_flags);
+	if (!lgp->args.layout.pages) {
+		kfree(lgp);
+		return NULL;
+	}
+	lgp->args.layout.pglen = max_pages * PAGE_SIZE;
+	lgp->res.layoutp = &lgp->args.layout;
+
+	/* Don't confuse uninitialised result and success */
+	lgp->res.status = -NFS4ERR_DELAY;
+
+	lgp->args.minlength = PAGE_SIZE;
+	if (lgp->args.minlength > range->length)
+		lgp->args.minlength = range->length;
+	if (ino) {
+		loff_t i_size = i_size_read(ino);
+
+		if (range->iomode == IOMODE_READ) {
+			if (range->offset >= i_size)
+				lgp->args.minlength = 0;
+			else if (i_size - range->offset < lgp->args.minlength)
+				lgp->args.minlength = i_size - range->offset;
+		}
+	}
+	lgp->args.maxcount = PNFS_LAYOUT_MAXSIZE;
+	pnfs_copy_range(&lgp->args.range, range);
+	lgp->args.type = server->pnfs_curr_ld->id;
+	lgp->args.inode = ino;
+	lgp->args.ctx = get_nfs_open_context(ctx);
+	nfs4_stateid_copy(&lgp->args.stateid, stateid);
+	lgp->gfp_flags = gfp_flags;
+	lgp->cred = get_rpccred(ctx->cred);
+	return lgp;
+}
+
+void pnfs_layoutget_free(struct nfs4_layoutget *lgp)
+{
+	size_t max_pages = lgp->args.layout.pglen / PAGE_SIZE;
+
+	nfs4_free_pages(lgp->args.layout.pages, max_pages);
+	if (lgp->args.inode)
+		pnfs_put_layout_hdr(NFS_I(lgp->args.inode)->layout);
+	put_rpccred(lgp->cred);
+	put_nfs_open_context(lgp->args.ctx);
+	kfree(lgp);
+}
+
+static void pnfs_clear_layoutcommit(struct inode *inode,
+		struct list_head *head)
+{
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct pnfs_layout_segment *lseg, *tmp;
+
+	if (!test_and_clear_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags))
+		return;
+	list_for_each_entry_safe(lseg, tmp, &nfsi->layout->plh_segs, pls_list) {
+		if (!test_and_clear_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags))
+			continue;
+		pnfs_lseg_dec_and_remove_zero(lseg, head);
+	}
+}
+
+void pnfs_layoutreturn_free_lsegs(struct pnfs_layout_hdr *lo,
+		const nfs4_stateid *arg_stateid,
+		const struct pnfs_layout_range *range,
+		const nfs4_stateid *stateid)
+{
+	struct inode *inode = lo->plh_inode;
+	LIST_HEAD(freeme);
+
+	spin_lock(&inode->i_lock);
+	if (!pnfs_layout_is_valid(lo) || !arg_stateid ||
+	    !nfs4_stateid_match_other(&lo->plh_stateid, arg_stateid))
+		goto out_unlock;
+	if (stateid) {
+		u32 seq = be32_to_cpu(arg_stateid->seqid);
+
+		pnfs_mark_matching_lsegs_invalid(lo, &freeme, range, seq);
+		pnfs_free_returned_lsegs(lo, &freeme, range, seq);
+		pnfs_set_layout_stateid(lo, stateid, true);
+	} else
+		pnfs_mark_layout_stateid_invalid(lo, &freeme);
+out_unlock:
+	pnfs_clear_layoutreturn_waitbit(lo);
+	spin_unlock(&inode->i_lock);
+	pnfs_free_lseg_list(&freeme);
+
+}
+
+static bool
+pnfs_prepare_layoutreturn(struct pnfs_layout_hdr *lo,
+		nfs4_stateid *stateid,
+		enum pnfs_iomode *iomode)
+{
+	/* Serialise LAYOUTGET/LAYOUTRETURN */
+	if (atomic_read(&lo->plh_outstanding) != 0)
+		return false;
+	if (test_and_set_bit(NFS_LAYOUT_RETURN_LOCK, &lo->plh_flags))
+		return false;
+	set_bit(NFS_LAYOUT_RETURN, &lo->plh_flags);
+	pnfs_get_layout_hdr(lo);
+	if (test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags)) {
+		if (stateid != NULL) {
+			nfs4_stateid_copy(stateid, &lo->plh_stateid);
+			if (lo->plh_return_seq != 0)
+				stateid->seqid = cpu_to_be32(lo->plh_return_seq);
+		}
+		if (iomode != NULL)
+			*iomode = lo->plh_return_iomode;
+		pnfs_clear_layoutreturn_info(lo);
+		return true;
+	}
+	if (stateid != NULL)
+		nfs4_stateid_copy(stateid, &lo->plh_stateid);
+	if (iomode != NULL)
+		*iomode = IOMODE_ANY;
+	return true;
+}
+
+static void
+pnfs_init_layoutreturn_args(struct nfs4_layoutreturn_args *args,
+		struct pnfs_layout_hdr *lo,
+		const nfs4_stateid *stateid,
+		enum pnfs_iomode iomode)
+{
+	struct inode *inode = lo->plh_inode;
+
+	args->layout_type = NFS_SERVER(inode)->pnfs_curr_ld->id;
+	args->inode = inode;
+	args->range.iomode = iomode;
+	args->range.offset = 0;
+	args->range.length = NFS4_MAX_UINT64;
+	args->layout = lo;
+	nfs4_stateid_copy(&args->stateid, stateid);
+}
+
+static int
+pnfs_send_layoutreturn(struct pnfs_layout_hdr *lo, const nfs4_stateid *stateid,
+		       enum pnfs_iomode iomode, bool sync)
+{
+	struct inode *ino = lo->plh_inode;
+	struct pnfs_layoutdriver_type *ld = NFS_SERVER(ino)->pnfs_curr_ld;
+	struct nfs4_layoutreturn *lrp;
+	int status = 0;
+
+	lrp = kzalloc(sizeof(*lrp), GFP_NOFS);
+	if (unlikely(lrp == NULL)) {
+		status = -ENOMEM;
+		spin_lock(&ino->i_lock);
+		pnfs_clear_layoutreturn_waitbit(lo);
+		spin_unlock(&ino->i_lock);
+		pnfs_put_layout_hdr(lo);
+		goto out;
+	}
+
+	pnfs_init_layoutreturn_args(&lrp->args, lo, stateid, iomode);
+	lrp->args.ld_private = &lrp->ld_private;
+	lrp->clp = NFS_SERVER(ino)->nfs_client;
+	lrp->cred = lo->plh_lc_cred;
+	if (ld->prepare_layoutreturn)
+		ld->prepare_layoutreturn(&lrp->args);
+
+	status = nfs4_proc_layoutreturn(lrp, sync);
+out:
+	dprintk("<-- %s status: %d\n", __func__, status);
+	return status;
+}
+
+static bool
+pnfs_layout_segments_returnable(struct pnfs_layout_hdr *lo,
+				enum pnfs_iomode iomode,
+				u32 seq)
+{
+	struct pnfs_layout_range recall_range = {
+		.length = NFS4_MAX_UINT64,
+		.iomode = iomode,
+	};
+	return pnfs_mark_matching_lsegs_return(lo, &lo->plh_return_segs,
+					       &recall_range, seq) != -EBUSY;
+}
+
+/* Return true if layoutreturn is needed */
+static bool
+pnfs_layout_need_return(struct pnfs_layout_hdr *lo)
+{
+	if (!test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags))
+		return false;
+	return pnfs_layout_segments_returnable(lo, lo->plh_return_iomode,
+					       lo->plh_return_seq);
+}
+
+static void pnfs_layoutreturn_before_put_layout_hdr(struct pnfs_layout_hdr *lo)
+{
+	struct inode *inode= lo->plh_inode;
+
+	if (!test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags))
+		return;
+	spin_lock(&inode->i_lock);
+	if (pnfs_layout_need_return(lo)) {
+		nfs4_stateid stateid;
+		enum pnfs_iomode iomode;
+		bool send;
+
+		send = pnfs_prepare_layoutreturn(lo, &stateid, &iomode);
+		spin_unlock(&inode->i_lock);
+		if (send) {
+			/* Send an async layoutreturn so we dont deadlock */
+			pnfs_send_layoutreturn(lo, &stateid, iomode, false);
+		}
+	} else
+		spin_unlock(&inode->i_lock);
+}
+
+/*
+ * Initiates a LAYOUTRETURN(FILE), and removes the pnfs_layout_hdr
+ * when the layout segment list is empty.
+ *
+ * Note that a pnfs_layout_hdr can exist with an empty layout segment
+ * list when LAYOUTGET has failed, or when LAYOUTGET succeeded, but the
+ * deviceid is marked invalid.
+ */
+int
+_pnfs_return_layout(struct inode *ino)
+{
+	struct pnfs_layout_hdr *lo = NULL;
+	struct nfs_inode *nfsi = NFS_I(ino);
+	struct pnfs_layout_range range = {
+		.iomode		= IOMODE_ANY,
+		.offset		= 0,
+		.length		= NFS4_MAX_UINT64,
+	};
+	LIST_HEAD(tmp_list);
+	nfs4_stateid stateid;
+	int status = 0;
+	bool send, valid_layout;
+
+	dprintk("NFS: %s for inode %lu\n", __func__, ino->i_ino);
+
+	spin_lock(&ino->i_lock);
+	lo = nfsi->layout;
+	if (!lo) {
+		spin_unlock(&ino->i_lock);
+		dprintk("NFS: %s no layout to return\n", __func__);
+		goto out;
+	}
+	/* Reference matched in nfs4_layoutreturn_release */
+	pnfs_get_layout_hdr(lo);
+	/* Is there an outstanding layoutreturn ? */
+	if (test_bit(NFS_LAYOUT_RETURN_LOCK, &lo->plh_flags)) {
+		spin_unlock(&ino->i_lock);
+		if (wait_on_bit(&lo->plh_flags, NFS_LAYOUT_RETURN,
+					TASK_UNINTERRUPTIBLE))
+			goto out_put_layout_hdr;
+		spin_lock(&ino->i_lock);
+	}
+	valid_layout = pnfs_layout_is_valid(lo);
+	pnfs_clear_layoutcommit(ino, &tmp_list);
+	pnfs_mark_matching_lsegs_return(lo, &tmp_list, &range, 0);
+
+	if (NFS_SERVER(ino)->pnfs_curr_ld->return_range)
+		NFS_SERVER(ino)->pnfs_curr_ld->return_range(lo, &range);
+
+	/* Don't send a LAYOUTRETURN if list was initially empty */
+	if (!test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags) ||
+			!valid_layout) {
+		spin_unlock(&ino->i_lock);
+		dprintk("NFS: %s no layout segments to return\n", __func__);
+		goto out_put_layout_hdr;
+	}
+
+	send = pnfs_prepare_layoutreturn(lo, &stateid, NULL);
+	spin_unlock(&ino->i_lock);
+	if (send)
+		status = pnfs_send_layoutreturn(lo, &stateid, IOMODE_ANY, true);
+out_put_layout_hdr:
+	pnfs_free_lseg_list(&tmp_list);
+	pnfs_put_layout_hdr(lo);
+out:
+	dprintk("<-- %s status: %d\n", __func__, status);
+	return status;
+}
+
+int
+pnfs_commit_and_return_layout(struct inode *inode)
+{
+	struct pnfs_layout_hdr *lo;
+	int ret;
+
+	spin_lock(&inode->i_lock);
+	lo = NFS_I(inode)->layout;
+	if (lo == NULL) {
+		spin_unlock(&inode->i_lock);
+		return 0;
+	}
+	pnfs_get_layout_hdr(lo);
+	/* Block new layoutgets and read/write to ds */
+	lo->plh_block_lgets++;
+	spin_unlock(&inode->i_lock);
+	filemap_fdatawait(inode->i_mapping);
+	ret = pnfs_layoutcommit_inode(inode, true);
+	if (ret == 0)
+		ret = _pnfs_return_layout(inode);
+	spin_lock(&inode->i_lock);
+	lo->plh_block_lgets--;
+	spin_unlock(&inode->i_lock);
+	pnfs_put_layout_hdr(lo);
+	return ret;
+}
+
+bool pnfs_roc(struct inode *ino,
+		struct nfs4_layoutreturn_args *args,
+		struct nfs4_layoutreturn_res *res,
+		const struct rpc_cred *cred)
+{
+	struct nfs_inode *nfsi = NFS_I(ino);
+	struct nfs_open_context *ctx;
+	struct nfs4_state *state;
+	struct pnfs_layout_hdr *lo;
+	struct pnfs_layout_segment *lseg, *next;
+	nfs4_stateid stateid;
+	enum pnfs_iomode iomode = 0;
+	bool layoutreturn = false, roc = false;
+	bool skip_read = false;
+
+	if (!nfs_have_layout(ino))
+		return false;
+retry:
+	spin_lock(&ino->i_lock);
+	lo = nfsi->layout;
+	if (!lo || !pnfs_layout_is_valid(lo) ||
+	    test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
+		lo = NULL;
+		goto out_noroc;
+	}
+	pnfs_get_layout_hdr(lo);
+	if (test_bit(NFS_LAYOUT_RETURN_LOCK, &lo->plh_flags)) {
+		spin_unlock(&ino->i_lock);
+		wait_on_bit(&lo->plh_flags, NFS_LAYOUT_RETURN,
+				TASK_UNINTERRUPTIBLE);
+		pnfs_put_layout_hdr(lo);
+		goto retry;
+	}
+
+	/* no roc if we hold a delegation */
+	if (nfs4_check_delegation(ino, FMODE_READ)) {
+		if (nfs4_check_delegation(ino, FMODE_WRITE))
+			goto out_noroc;
+		skip_read = true;
+	}
+
+	list_for_each_entry(ctx, &nfsi->open_files, list) {
+		state = ctx->state;
+		if (state == NULL)
+			continue;
+		/* Don't return layout if there is open file state */
+		if (state->state & FMODE_WRITE)
+			goto out_noroc;
+		if (state->state & FMODE_READ)
+			skip_read = true;
+	}
+
+
+	list_for_each_entry_safe(lseg, next, &lo->plh_segs, pls_list) {
+		if (skip_read && lseg->pls_range.iomode == IOMODE_READ)
+			continue;
+		/* If we are sending layoutreturn, invalidate all valid lsegs */
+		if (!test_and_clear_bit(NFS_LSEG_ROC, &lseg->pls_flags))
+			continue;
+		/*
+		 * Note: mark lseg for return so pnfs_layout_remove_lseg
+		 * doesn't invalidate the layout for us.
+		 */
+		set_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags);
+		if (!mark_lseg_invalid(lseg, &lo->plh_return_segs))
+			continue;
+		pnfs_set_plh_return_info(lo, lseg->pls_range.iomode, 0);
+	}
+
+	if (!test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags))
+		goto out_noroc;
+
+	/* ROC in two conditions:
+	 * 1. there are ROC lsegs
+	 * 2. we don't send layoutreturn
+	 */
+	/* lo ref dropped in pnfs_roc_release() */
+	layoutreturn = pnfs_prepare_layoutreturn(lo, &stateid, &iomode);
+	/* If the creds don't match, we can't compound the layoutreturn */
+	if (!layoutreturn || cred != lo->plh_lc_cred)
+		goto out_noroc;
+
+	roc = layoutreturn;
+	pnfs_init_layoutreturn_args(args, lo, &stateid, iomode);
+	res->lrs_present = 0;
+	layoutreturn = false;
+
+out_noroc:
+	spin_unlock(&ino->i_lock);
+	pnfs_layoutcommit_inode(ino, true);
+	if (roc) {
+		struct pnfs_layoutdriver_type *ld = NFS_SERVER(ino)->pnfs_curr_ld;
+		if (ld->prepare_layoutreturn)
+			ld->prepare_layoutreturn(args);
+		pnfs_put_layout_hdr(lo);
+		return true;
+	}
+	if (layoutreturn)
+		pnfs_send_layoutreturn(lo, &stateid, iomode, true);
+	pnfs_put_layout_hdr(lo);
+	return false;
+}
+
+void pnfs_roc_release(struct nfs4_layoutreturn_args *args,
+		struct nfs4_layoutreturn_res *res,
+		int ret)
+{
+	struct pnfs_layout_hdr *lo = args->layout;
+	struct inode *inode = args->inode;
+	const nfs4_stateid *arg_stateid = NULL;
+	const nfs4_stateid *res_stateid = NULL;
+	struct nfs4_xdr_opaque_data *ld_private = args->ld_private;
+
+	switch (ret) {
+	case -NFS4ERR_NOMATCHING_LAYOUT:
+		spin_lock(&inode->i_lock);
+		if (pnfs_layout_is_valid(lo) &&
+		    nfs4_stateid_match_other(&args->stateid, &lo->plh_stateid))
+			pnfs_set_plh_return_info(lo, args->range.iomode, 0);
+		spin_unlock(&inode->i_lock);
+		break;
+	case 0:
+		if (res->lrs_present)
+			res_stateid = &res->stateid;
+		/* Fallthrough */
+	default:
+		arg_stateid = &args->stateid;
+	}
+	pnfs_layoutreturn_free_lsegs(lo, arg_stateid, &args->range,
+			res_stateid);
+	if (ld_private && ld_private->ops && ld_private->ops->free)
+		ld_private->ops->free(ld_private);
+	pnfs_put_layout_hdr(lo);
+	trace_nfs4_layoutreturn_on_close(args->inode, 0);
+}
+
+bool pnfs_wait_on_layoutreturn(struct inode *ino, struct rpc_task *task)
+{
+	struct nfs_inode *nfsi = NFS_I(ino);
+        struct pnfs_layout_hdr *lo;
+        bool sleep = false;
+
+	/* we might not have grabbed lo reference. so need to check under
+	 * i_lock */
+        spin_lock(&ino->i_lock);
+        lo = nfsi->layout;
+        if (lo && test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags)) {
+                rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
+                sleep = true;
+	}
+        spin_unlock(&ino->i_lock);
+        return sleep;
+}
+
+/*
+ * Compare two layout segments for sorting into layout cache.
+ * We want to preferentially return RW over RO layouts, so ensure those
+ * are seen first.
+ */
+static s64
+pnfs_lseg_range_cmp(const struct pnfs_layout_range *l1,
+	   const struct pnfs_layout_range *l2)
+{
+	s64 d;
+
+	/* high offset > low offset */
+	d = l1->offset - l2->offset;
+	if (d)
+		return d;
+
+	/* short length > long length */
+	d = l2->length - l1->length;
+	if (d)
+		return d;
+
+	/* read > read/write */
+	return (int)(l1->iomode == IOMODE_READ) - (int)(l2->iomode == IOMODE_READ);
+}
+
+static bool
+pnfs_lseg_range_is_after(const struct pnfs_layout_range *l1,
+		const struct pnfs_layout_range *l2)
+{
+	return pnfs_lseg_range_cmp(l1, l2) > 0;
+}
+
+static bool
+pnfs_lseg_no_merge(struct pnfs_layout_segment *lseg,
+		struct pnfs_layout_segment *old)
+{
+	return false;
+}
+
+void
+pnfs_generic_layout_insert_lseg(struct pnfs_layout_hdr *lo,
+		   struct pnfs_layout_segment *lseg,
+		   bool (*is_after)(const struct pnfs_layout_range *,
+			   const struct pnfs_layout_range *),
+		   bool (*do_merge)(struct pnfs_layout_segment *,
+			   struct pnfs_layout_segment *),
+		   struct list_head *free_me)
+{
+	struct pnfs_layout_segment *lp, *tmp;
+
+	dprintk("%s:Begin\n", __func__);
+
+	list_for_each_entry_safe(lp, tmp, &lo->plh_segs, pls_list) {
+		if (test_bit(NFS_LSEG_VALID, &lp->pls_flags) == 0)
+			continue;
+		if (do_merge(lseg, lp)) {
+			mark_lseg_invalid(lp, free_me);
+			continue;
+		}
+		if (is_after(&lseg->pls_range, &lp->pls_range))
+			continue;
+		list_add_tail(&lseg->pls_list, &lp->pls_list);
+		dprintk("%s: inserted lseg %p "
+			"iomode %d offset %llu length %llu before "
+			"lp %p iomode %d offset %llu length %llu\n",
+			__func__, lseg, lseg->pls_range.iomode,
+			lseg->pls_range.offset, lseg->pls_range.length,
+			lp, lp->pls_range.iomode, lp->pls_range.offset,
+			lp->pls_range.length);
+		goto out;
+	}
+	list_add_tail(&lseg->pls_list, &lo->plh_segs);
+	dprintk("%s: inserted lseg %p "
+		"iomode %d offset %llu length %llu at tail\n",
+		__func__, lseg, lseg->pls_range.iomode,
+		lseg->pls_range.offset, lseg->pls_range.length);
+out:
+	pnfs_get_layout_hdr(lo);
+
+	dprintk("%s:Return\n", __func__);
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_layout_insert_lseg);
+
+static void
+pnfs_layout_insert_lseg(struct pnfs_layout_hdr *lo,
+		   struct pnfs_layout_segment *lseg,
+		   struct list_head *free_me)
+{
+	struct inode *inode = lo->plh_inode;
+	struct pnfs_layoutdriver_type *ld = NFS_SERVER(inode)->pnfs_curr_ld;
+
+	if (ld->add_lseg != NULL)
+		ld->add_lseg(lo, lseg, free_me);
+	else
+		pnfs_generic_layout_insert_lseg(lo, lseg,
+				pnfs_lseg_range_is_after,
+				pnfs_lseg_no_merge,
+				free_me);
+}
+
+static struct pnfs_layout_hdr *
+alloc_init_layout_hdr(struct inode *ino,
+		      struct nfs_open_context *ctx,
+		      gfp_t gfp_flags)
+{
+	struct pnfs_layout_hdr *lo;
+
+	lo = pnfs_alloc_layout_hdr(ino, gfp_flags);
+	if (!lo)
+		return NULL;
+	refcount_set(&lo->plh_refcount, 1);
+	INIT_LIST_HEAD(&lo->plh_layouts);
+	INIT_LIST_HEAD(&lo->plh_segs);
+	INIT_LIST_HEAD(&lo->plh_return_segs);
+	INIT_LIST_HEAD(&lo->plh_bulk_destroy);
+	lo->plh_inode = ino;
+	lo->plh_lc_cred = get_rpccred(ctx->cred);
+	lo->plh_flags |= 1 << NFS_LAYOUT_INVALID_STID;
+	return lo;
+}
+
+static struct pnfs_layout_hdr *
+pnfs_find_alloc_layout(struct inode *ino,
+		       struct nfs_open_context *ctx,
+		       gfp_t gfp_flags)
+	__releases(&ino->i_lock)
+	__acquires(&ino->i_lock)
+{
+	struct nfs_inode *nfsi = NFS_I(ino);
+	struct pnfs_layout_hdr *new = NULL;
+
+	dprintk("%s Begin ino=%p layout=%p\n", __func__, ino, nfsi->layout);
+
+	if (nfsi->layout != NULL)
+		goto out_existing;
+	spin_unlock(&ino->i_lock);
+	new = alloc_init_layout_hdr(ino, ctx, gfp_flags);
+	spin_lock(&ino->i_lock);
+
+	if (likely(nfsi->layout == NULL)) {	/* Won the race? */
+		nfsi->layout = new;
+		return new;
+	} else if (new != NULL)
+		pnfs_free_layout_hdr(new);
+out_existing:
+	pnfs_get_layout_hdr(nfsi->layout);
+	return nfsi->layout;
+}
+
+/*
+ * iomode matching rules:
+ * iomode	lseg	strict match
+ *                      iomode
+ * -----	-----	------ -----
+ * ANY		READ	N/A    true
+ * ANY		RW	N/A    true
+ * RW		READ	N/A    false
+ * RW		RW	N/A    true
+ * READ		READ	N/A    true
+ * READ		RW	true   false
+ * READ		RW	false  true
+ */
+static bool
+pnfs_lseg_range_match(const struct pnfs_layout_range *ls_range,
+		 const struct pnfs_layout_range *range,
+		 bool strict_iomode)
+{
+	struct pnfs_layout_range range1;
+
+	if ((range->iomode == IOMODE_RW &&
+	     ls_range->iomode != IOMODE_RW) ||
+	    (range->iomode != ls_range->iomode &&
+	     strict_iomode) ||
+	    !pnfs_lseg_range_intersecting(ls_range, range))
+		return false;
+
+	/* range1 covers only the first byte in the range */
+	range1 = *range;
+	range1.length = 1;
+	return pnfs_lseg_range_contained(ls_range, &range1);
+}
+
+/*
+ * lookup range in layout
+ */
+static struct pnfs_layout_segment *
+pnfs_find_lseg(struct pnfs_layout_hdr *lo,
+		struct pnfs_layout_range *range,
+		bool strict_iomode)
+{
+	struct pnfs_layout_segment *lseg, *ret = NULL;
+
+	dprintk("%s:Begin\n", __func__);
+
+	list_for_each_entry(lseg, &lo->plh_segs, pls_list) {
+		if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags) &&
+		    pnfs_lseg_range_match(&lseg->pls_range, range,
+					  strict_iomode)) {
+			ret = pnfs_get_lseg(lseg);
+			break;
+		}
+	}
+
+	dprintk("%s:Return lseg %p ref %d\n",
+		__func__, ret, ret ? refcount_read(&ret->pls_refcount) : 0);
+	return ret;
+}
+
+/*
+ * Use mdsthreshold hints set at each OPEN to determine if I/O should go
+ * to the MDS or over pNFS
+ *
+ * The nfs_inode read_io and write_io fields are cumulative counters reset
+ * when there are no layout segments. Note that in pnfs_update_layout iomode
+ * is set to IOMODE_READ for a READ request, and set to IOMODE_RW for a
+ * WRITE request.
+ *
+ * A return of true means use MDS I/O.
+ *
+ * From rfc 5661:
+ * If a file's size is smaller than the file size threshold, data accesses
+ * SHOULD be sent to the metadata server.  If an I/O request has a length that
+ * is below the I/O size threshold, the I/O SHOULD be sent to the metadata
+ * server.  If both file size and I/O size are provided, the client SHOULD
+ * reach or exceed  both thresholds before sending its read or write
+ * requests to the data server.
+ */
+static bool pnfs_within_mdsthreshold(struct nfs_open_context *ctx,
+				     struct inode *ino, int iomode)
+{
+	struct nfs4_threshold *t = ctx->mdsthreshold;
+	struct nfs_inode *nfsi = NFS_I(ino);
+	loff_t fsize = i_size_read(ino);
+	bool size = false, size_set = false, io = false, io_set = false, ret = false;
+
+	if (t == NULL)
+		return ret;
+
+	dprintk("%s bm=0x%x rd_sz=%llu wr_sz=%llu rd_io=%llu wr_io=%llu\n",
+		__func__, t->bm, t->rd_sz, t->wr_sz, t->rd_io_sz, t->wr_io_sz);
+
+	switch (iomode) {
+	case IOMODE_READ:
+		if (t->bm & THRESHOLD_RD) {
+			dprintk("%s fsize %llu\n", __func__, fsize);
+			size_set = true;
+			if (fsize < t->rd_sz)
+				size = true;
+		}
+		if (t->bm & THRESHOLD_RD_IO) {
+			dprintk("%s nfsi->read_io %llu\n", __func__,
+				nfsi->read_io);
+			io_set = true;
+			if (nfsi->read_io < t->rd_io_sz)
+				io = true;
+		}
+		break;
+	case IOMODE_RW:
+		if (t->bm & THRESHOLD_WR) {
+			dprintk("%s fsize %llu\n", __func__, fsize);
+			size_set = true;
+			if (fsize < t->wr_sz)
+				size = true;
+		}
+		if (t->bm & THRESHOLD_WR_IO) {
+			dprintk("%s nfsi->write_io %llu\n", __func__,
+				nfsi->write_io);
+			io_set = true;
+			if (nfsi->write_io < t->wr_io_sz)
+				io = true;
+		}
+		break;
+	}
+	if (size_set && io_set) {
+		if (size && io)
+			ret = true;
+	} else if (size || io)
+		ret = true;
+
+	dprintk("<-- %s size %d io %d ret %d\n", __func__, size, io, ret);
+	return ret;
+}
+
+static int pnfs_prepare_to_retry_layoutget(struct pnfs_layout_hdr *lo)
+{
+	/*
+	 * send layoutcommit as it can hold up layoutreturn due to lseg
+	 * reference
+	 */
+	pnfs_layoutcommit_inode(lo->plh_inode, false);
+	return wait_on_bit_action(&lo->plh_flags, NFS_LAYOUT_RETURN,
+				   nfs_wait_bit_killable,
+				   TASK_KILLABLE);
+}
+
+static void nfs_layoutget_begin(struct pnfs_layout_hdr *lo)
+{
+	atomic_inc(&lo->plh_outstanding);
+}
+
+static void nfs_layoutget_end(struct pnfs_layout_hdr *lo)
+{
+	if (atomic_dec_and_test(&lo->plh_outstanding))
+		wake_up_var(&lo->plh_outstanding);
+}
+
+static void pnfs_clear_first_layoutget(struct pnfs_layout_hdr *lo)
+{
+	unsigned long *bitlock = &lo->plh_flags;
+
+	clear_bit_unlock(NFS_LAYOUT_FIRST_LAYOUTGET, bitlock);
+	smp_mb__after_atomic();
+	wake_up_bit(bitlock, NFS_LAYOUT_FIRST_LAYOUTGET);
+}
+
+static void _add_to_server_list(struct pnfs_layout_hdr *lo,
+				struct nfs_server *server)
+{
+	if (list_empty(&lo->plh_layouts)) {
+		struct nfs_client *clp = server->nfs_client;
+
+		/* The lo must be on the clp list if there is any
+		 * chance of a CB_LAYOUTRECALL(FILE) coming in.
+		 */
+		spin_lock(&clp->cl_lock);
+		if (list_empty(&lo->plh_layouts))
+			list_add_tail(&lo->plh_layouts, &server->layouts);
+		spin_unlock(&clp->cl_lock);
+	}
+}
+
+/*
+ * Layout segment is retreived from the server if not cached.
+ * The appropriate layout segment is referenced and returned to the caller.
+ */
+struct pnfs_layout_segment *
+pnfs_update_layout(struct inode *ino,
+		   struct nfs_open_context *ctx,
+		   loff_t pos,
+		   u64 count,
+		   enum pnfs_iomode iomode,
+		   bool strict_iomode,
+		   gfp_t gfp_flags)
+{
+	struct pnfs_layout_range arg = {
+		.iomode = iomode,
+		.offset = pos,
+		.length = count,
+	};
+	unsigned pg_offset;
+	struct nfs_server *server = NFS_SERVER(ino);
+	struct nfs_client *clp = server->nfs_client;
+	struct pnfs_layout_hdr *lo = NULL;
+	struct pnfs_layout_segment *lseg = NULL;
+	struct nfs4_layoutget *lgp;
+	nfs4_stateid stateid;
+	long timeout = 0;
+	unsigned long giveup = jiffies + (clp->cl_lease_time << 1);
+	bool first;
+
+	if (!pnfs_enabled_sb(NFS_SERVER(ino))) {
+		trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
+				 PNFS_UPDATE_LAYOUT_NO_PNFS);
+		goto out;
+	}
+
+	if (pnfs_within_mdsthreshold(ctx, ino, iomode)) {
+		trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
+				 PNFS_UPDATE_LAYOUT_MDSTHRESH);
+		goto out;
+	}
+
+lookup_again:
+	lseg = ERR_PTR(nfs4_client_recover_expired_lease(clp));
+	if (IS_ERR(lseg))
+		goto out;
+	first = false;
+	spin_lock(&ino->i_lock);
+	lo = pnfs_find_alloc_layout(ino, ctx, gfp_flags);
+	if (lo == NULL) {
+		spin_unlock(&ino->i_lock);
+		lseg = ERR_PTR(-ENOMEM);
+		trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
+				 PNFS_UPDATE_LAYOUT_NOMEM);
+		goto out;
+	}
+
+	/* Do we even need to bother with this? */
+	if (test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
+		trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
+				 PNFS_UPDATE_LAYOUT_BULK_RECALL);
+		dprintk("%s matches recall, use MDS\n", __func__);
+		goto out_unlock;
+	}
+
+	/* if LAYOUTGET already failed once we don't try again */
+	if (pnfs_layout_io_test_failed(lo, iomode)) {
+		trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
+				 PNFS_UPDATE_LAYOUT_IO_TEST_FAIL);
+		goto out_unlock;
+	}
+
+	/*
+	 * If the layout segment list is empty, but there are outstanding
+	 * layoutget calls, then they might be subject to a layoutrecall.
+	 */
+	if (list_empty(&lo->plh_segs) &&
+	    atomic_read(&lo->plh_outstanding) != 0) {
+		spin_unlock(&ino->i_lock);
+		lseg = ERR_PTR(wait_var_event_killable(&lo->plh_outstanding,
+					!atomic_read(&lo->plh_outstanding)));
+		if (IS_ERR(lseg))
+			goto out_put_layout_hdr;
+		pnfs_put_layout_hdr(lo);
+		goto lookup_again;
+	}
+
+	lseg = pnfs_find_lseg(lo, &arg, strict_iomode);
+	if (lseg) {
+		trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
+				PNFS_UPDATE_LAYOUT_FOUND_CACHED);
+		goto out_unlock;
+	}
+
+	if (!nfs4_valid_open_stateid(ctx->state)) {
+		trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
+				PNFS_UPDATE_LAYOUT_INVALID_OPEN);
+		goto out_unlock;
+	}
+
+	/*
+	 * Choose a stateid for the LAYOUTGET. If we don't have a layout
+	 * stateid, or it has been invalidated, then we must use the open
+	 * stateid.
+	 */
+	if (test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags)) {
+
+		/*
+		 * The first layoutget for the file. Need to serialize per
+		 * RFC 5661 Errata 3208.
+		 */
+		if (test_and_set_bit(NFS_LAYOUT_FIRST_LAYOUTGET,
+				     &lo->plh_flags)) {
+			spin_unlock(&ino->i_lock);
+			lseg = ERR_PTR(wait_on_bit(&lo->plh_flags,
+						NFS_LAYOUT_FIRST_LAYOUTGET,
+						TASK_KILLABLE));
+			if (IS_ERR(lseg))
+				goto out_put_layout_hdr;
+			pnfs_put_layout_hdr(lo);
+			dprintk("%s retrying\n", __func__);
+			goto lookup_again;
+		}
+
+		first = true;
+		if (nfs4_select_rw_stateid(ctx->state,
+					iomode == IOMODE_RW ? FMODE_WRITE : FMODE_READ,
+					NULL, &stateid, NULL) != 0) {
+			trace_pnfs_update_layout(ino, pos, count,
+					iomode, lo, lseg,
+					PNFS_UPDATE_LAYOUT_INVALID_OPEN);
+			goto out_unlock;
+		}
+	} else {
+		nfs4_stateid_copy(&stateid, &lo->plh_stateid);
+	}
+
+	/*
+	 * Because we free lsegs before sending LAYOUTRETURN, we need to wait
+	 * for LAYOUTRETURN even if first is true.
+	 */
+	if (test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags)) {
+		spin_unlock(&ino->i_lock);
+		dprintk("%s wait for layoutreturn\n", __func__);
+		lseg = ERR_PTR(pnfs_prepare_to_retry_layoutget(lo));
+		if (!IS_ERR(lseg)) {
+			if (first)
+				pnfs_clear_first_layoutget(lo);
+			pnfs_put_layout_hdr(lo);
+			dprintk("%s retrying\n", __func__);
+			trace_pnfs_update_layout(ino, pos, count, iomode, lo,
+					lseg, PNFS_UPDATE_LAYOUT_RETRY);
+			goto lookup_again;
+		}
+		trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
+				PNFS_UPDATE_LAYOUT_RETURN);
+		goto out_put_layout_hdr;
+	}
+
+	if (pnfs_layoutgets_blocked(lo)) {
+		trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
+				PNFS_UPDATE_LAYOUT_BLOCKED);
+		goto out_unlock;
+	}
+	nfs_layoutget_begin(lo);
+	spin_unlock(&ino->i_lock);
+
+	_add_to_server_list(lo, server);
+
+	pg_offset = arg.offset & ~PAGE_MASK;
+	if (pg_offset) {
+		arg.offset -= pg_offset;
+		arg.length += pg_offset;
+	}
+	if (arg.length != NFS4_MAX_UINT64)
+		arg.length = PAGE_ALIGN(arg.length);
+
+	lgp = pnfs_alloc_init_layoutget_args(ino, ctx, &stateid, &arg, gfp_flags);
+	if (!lgp) {
+		lseg = ERR_PTR(-ENOMEM);
+		trace_pnfs_update_layout(ino, pos, count, iomode, lo, NULL,
+					 PNFS_UPDATE_LAYOUT_NOMEM);
+		nfs_layoutget_end(lo);
+		goto out_put_layout_hdr;
+	}
+
+	lseg = nfs4_proc_layoutget(lgp, &timeout);
+	trace_pnfs_update_layout(ino, pos, count, iomode, lo, lseg,
+				 PNFS_UPDATE_LAYOUT_SEND_LAYOUTGET);
+	nfs_layoutget_end(lo);
+	if (IS_ERR(lseg)) {
+		switch(PTR_ERR(lseg)) {
+		case -EBUSY:
+			if (time_after(jiffies, giveup))
+				lseg = NULL;
+			break;
+		case -ERECALLCONFLICT:
+		case -EAGAIN:
+			break;
+		case -ENODATA:
+			/* The server returned NFS4ERR_LAYOUTUNAVAILABLE */
+			pnfs_layout_set_fail_bit(
+				lo, pnfs_iomode_to_fail_bit(iomode));
+			lseg = NULL;
+			goto out_put_layout_hdr;
+		default:
+			if (!nfs_error_is_fatal(PTR_ERR(lseg))) {
+				pnfs_layout_clear_fail_bit(lo, pnfs_iomode_to_fail_bit(iomode));
+				lseg = NULL;
+			}
+			goto out_put_layout_hdr;
+		}
+		if (lseg) {
+			if (first)
+				pnfs_clear_first_layoutget(lo);
+			trace_pnfs_update_layout(ino, pos, count,
+				iomode, lo, lseg, PNFS_UPDATE_LAYOUT_RETRY);
+			pnfs_put_layout_hdr(lo);
+			goto lookup_again;
+		}
+	} else {
+		pnfs_layout_clear_fail_bit(lo, pnfs_iomode_to_fail_bit(iomode));
+	}
+
+out_put_layout_hdr:
+	if (first)
+		pnfs_clear_first_layoutget(lo);
+	pnfs_put_layout_hdr(lo);
+out:
+	dprintk("%s: inode %s/%llu pNFS layout segment %s for "
+			"(%s, offset: %llu, length: %llu)\n",
+			__func__, ino->i_sb->s_id,
+			(unsigned long long)NFS_FILEID(ino),
+			IS_ERR_OR_NULL(lseg) ? "not found" : "found",
+			iomode==IOMODE_RW ?  "read/write" : "read-only",
+			(unsigned long long)pos,
+			(unsigned long long)count);
+	return lseg;
+out_unlock:
+	spin_unlock(&ino->i_lock);
+	goto out_put_layout_hdr;
+}
+EXPORT_SYMBOL_GPL(pnfs_update_layout);
+
+static bool
+pnfs_sanity_check_layout_range(struct pnfs_layout_range *range)
+{
+	switch (range->iomode) {
+	case IOMODE_READ:
+	case IOMODE_RW:
+		break;
+	default:
+		return false;
+	}
+	if (range->offset == NFS4_MAX_UINT64)
+		return false;
+	if (range->length == 0)
+		return false;
+	if (range->length != NFS4_MAX_UINT64 &&
+	    range->length > NFS4_MAX_UINT64 - range->offset)
+		return false;
+	return true;
+}
+
+static struct pnfs_layout_hdr *
+_pnfs_grab_empty_layout(struct inode *ino, struct nfs_open_context *ctx)
+{
+	struct pnfs_layout_hdr *lo;
+
+	spin_lock(&ino->i_lock);
+	lo = pnfs_find_alloc_layout(ino, ctx, GFP_KERNEL);
+	if (!lo)
+		goto out_unlock;
+	if (!test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags))
+		goto out_unlock;
+	if (test_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
+		goto out_unlock;
+	if (pnfs_layoutgets_blocked(lo))
+		goto out_unlock;
+	if (test_and_set_bit(NFS_LAYOUT_FIRST_LAYOUTGET, &lo->plh_flags))
+		goto out_unlock;
+	nfs_layoutget_begin(lo);
+	spin_unlock(&ino->i_lock);
+	_add_to_server_list(lo, NFS_SERVER(ino));
+	return lo;
+
+out_unlock:
+	spin_unlock(&ino->i_lock);
+	pnfs_put_layout_hdr(lo);
+	return NULL;
+}
+
+extern const nfs4_stateid current_stateid;
+
+static void _lgopen_prepare_attached(struct nfs4_opendata *data,
+				     struct nfs_open_context *ctx)
+{
+	struct inode *ino = data->dentry->d_inode;
+	struct pnfs_layout_range rng = {
+		.iomode = (data->o_arg.fmode & FMODE_WRITE) ?
+			  IOMODE_RW: IOMODE_READ,
+		.offset = 0,
+		.length = NFS4_MAX_UINT64,
+	};
+	struct nfs4_layoutget *lgp;
+	struct pnfs_layout_hdr *lo;
+
+	/* Heuristic: don't send layoutget if we have cached data */
+	if (rng.iomode == IOMODE_READ &&
+	   (i_size_read(ino) == 0 || ino->i_mapping->nrpages != 0))
+		return;
+
+	lo = _pnfs_grab_empty_layout(ino, ctx);
+	if (!lo)
+		return;
+	lgp = pnfs_alloc_init_layoutget_args(ino, ctx, &current_stateid,
+					     &rng, GFP_KERNEL);
+	if (!lgp) {
+		pnfs_clear_first_layoutget(lo);
+		nfs_layoutget_end(lo);
+		pnfs_put_layout_hdr(lo);
+		return;
+	}
+	data->lgp = lgp;
+	data->o_arg.lg_args = &lgp->args;
+	data->o_res.lg_res = &lgp->res;
+}
+
+static void _lgopen_prepare_floating(struct nfs4_opendata *data,
+				     struct nfs_open_context *ctx)
+{
+	struct pnfs_layout_range rng = {
+		.iomode = (data->o_arg.fmode & FMODE_WRITE) ?
+			  IOMODE_RW: IOMODE_READ,
+		.offset = 0,
+		.length = NFS4_MAX_UINT64,
+	};
+	struct nfs4_layoutget *lgp;
+
+	lgp = pnfs_alloc_init_layoutget_args(NULL, ctx, &current_stateid,
+					     &rng, GFP_KERNEL);
+	if (!lgp)
+		return;
+	data->lgp = lgp;
+	data->o_arg.lg_args = &lgp->args;
+	data->o_res.lg_res = &lgp->res;
+}
+
+void pnfs_lgopen_prepare(struct nfs4_opendata *data,
+			 struct nfs_open_context *ctx)
+{
+	struct nfs_server *server = NFS_SERVER(data->dir->d_inode);
+
+	if (!(pnfs_enabled_sb(server) &&
+	      server->pnfs_curr_ld->flags & PNFS_LAYOUTGET_ON_OPEN))
+		return;
+	/* Could check on max_ops, but currently hardcoded high enough */
+	if (!nfs_server_capable(data->dir->d_inode, NFS_CAP_LGOPEN))
+		return;
+	if (data->state)
+		_lgopen_prepare_attached(data, ctx);
+	else
+		_lgopen_prepare_floating(data, ctx);
+}
+
+void pnfs_parse_lgopen(struct inode *ino, struct nfs4_layoutget *lgp,
+		       struct nfs_open_context *ctx)
+{
+	struct pnfs_layout_hdr *lo;
+	struct pnfs_layout_segment *lseg;
+	struct nfs_server *srv = NFS_SERVER(ino);
+	u32 iomode;
+
+	if (!lgp)
+		return;
+	dprintk("%s: entered with status %i\n", __func__, lgp->res.status);
+	if (lgp->res.status) {
+		switch (lgp->res.status) {
+		default:
+			break;
+		/*
+		 * Halt lgopen attempts if the server doesn't recognise
+		 * the "current stateid" value, the layout type, or the
+		 * layoutget operation as being valid.
+		 * Also if it complains about too many ops in the compound
+		 * or of the request/reply being too big.
+		 */
+		case -NFS4ERR_BAD_STATEID:
+		case -NFS4ERR_NOTSUPP:
+		case -NFS4ERR_REP_TOO_BIG:
+		case -NFS4ERR_REP_TOO_BIG_TO_CACHE:
+		case -NFS4ERR_REQ_TOO_BIG:
+		case -NFS4ERR_TOO_MANY_OPS:
+		case -NFS4ERR_UNKNOWN_LAYOUTTYPE:
+			srv->caps &= ~NFS_CAP_LGOPEN;
+		}
+		return;
+	}
+	if (!lgp->args.inode) {
+		lo = _pnfs_grab_empty_layout(ino, ctx);
+		if (!lo)
+			return;
+		lgp->args.inode = ino;
+	} else
+		lo = NFS_I(lgp->args.inode)->layout;
+
+	lseg = pnfs_layout_process(lgp);
+	if (!IS_ERR(lseg)) {
+		iomode = lgp->args.range.iomode;
+		pnfs_layout_clear_fail_bit(lo, pnfs_iomode_to_fail_bit(iomode));
+		pnfs_put_lseg(lseg);
+	}
+}
+
+void nfs4_lgopen_release(struct nfs4_layoutget *lgp)
+{
+	if (lgp != NULL) {
+		struct inode *inode = lgp->args.inode;
+		if (inode) {
+			struct pnfs_layout_hdr *lo = NFS_I(inode)->layout;
+			pnfs_clear_first_layoutget(lo);
+			nfs_layoutget_end(lo);
+		}
+		pnfs_layoutget_free(lgp);
+	}
+}
+
+struct pnfs_layout_segment *
+pnfs_layout_process(struct nfs4_layoutget *lgp)
+{
+	struct pnfs_layout_hdr *lo = NFS_I(lgp->args.inode)->layout;
+	struct nfs4_layoutget_res *res = &lgp->res;
+	struct pnfs_layout_segment *lseg;
+	struct inode *ino = lo->plh_inode;
+	LIST_HEAD(free_me);
+
+	if (!pnfs_sanity_check_layout_range(&res->range))
+		return ERR_PTR(-EINVAL);
+
+	/* Inject layout blob into I/O device driver */
+	lseg = NFS_SERVER(ino)->pnfs_curr_ld->alloc_lseg(lo, res, lgp->gfp_flags);
+	if (IS_ERR_OR_NULL(lseg)) {
+		if (!lseg)
+			lseg = ERR_PTR(-ENOMEM);
+
+		dprintk("%s: Could not allocate layout: error %ld\n",
+		       __func__, PTR_ERR(lseg));
+		return lseg;
+	}
+
+	pnfs_init_lseg(lo, lseg, &res->range, &res->stateid);
+
+	spin_lock(&ino->i_lock);
+	if (pnfs_layoutgets_blocked(lo)) {
+		dprintk("%s forget reply due to state\n", __func__);
+		goto out_forget;
+	}
+
+	if (!pnfs_layout_is_valid(lo)) {
+		/* We have a completely new layout */
+		pnfs_set_layout_stateid(lo, &res->stateid, true);
+	} else if (nfs4_stateid_match_other(&lo->plh_stateid, &res->stateid)) {
+		/* existing state ID, make sure the sequence number matches. */
+		if (pnfs_layout_stateid_blocked(lo, &res->stateid)) {
+			dprintk("%s forget reply due to sequence\n", __func__);
+			goto out_forget;
+		}
+		pnfs_set_layout_stateid(lo, &res->stateid, false);
+	} else {
+		/*
+		 * We got an entirely new state ID.  Mark all segments for the
+		 * inode invalid, and retry the layoutget
+		 */
+		struct pnfs_layout_range range = {
+			.iomode = IOMODE_ANY,
+			.length = NFS4_MAX_UINT64,
+		};
+		pnfs_set_plh_return_info(lo, IOMODE_ANY, 0);
+		pnfs_mark_matching_lsegs_return(lo, &lo->plh_return_segs,
+						&range, 0);
+		goto out_forget;
+	}
+
+	pnfs_get_lseg(lseg);
+	pnfs_layout_insert_lseg(lo, lseg, &free_me);
+
+
+	if (res->return_on_close)
+		set_bit(NFS_LSEG_ROC, &lseg->pls_flags);
+
+	spin_unlock(&ino->i_lock);
+	pnfs_free_lseg_list(&free_me);
+	return lseg;
+
+out_forget:
+	spin_unlock(&ino->i_lock);
+	lseg->pls_layout = lo;
+	NFS_SERVER(ino)->pnfs_curr_ld->free_lseg(lseg);
+	pnfs_free_lseg_list(&free_me);
+	return ERR_PTR(-EAGAIN);
+}
+
+/**
+ * pnfs_mark_matching_lsegs_return - Free or return matching layout segments
+ * @lo: pointer to layout header
+ * @tmp_list: list header to be used with pnfs_free_lseg_list()
+ * @return_range: describe layout segment ranges to be returned
+ * @seq: stateid seqid to match
+ *
+ * This function is mainly intended for use by layoutrecall. It attempts
+ * to free the layout segment immediately, or else to mark it for return
+ * as soon as its reference count drops to zero.
+ *
+ * Returns
+ * - 0: a layoutreturn needs to be scheduled.
+ * - EBUSY: there are layout segment that are still in use.
+ * - ENOENT: there are no layout segments that need to be returned.
+ */
+int
+pnfs_mark_matching_lsegs_return(struct pnfs_layout_hdr *lo,
+				struct list_head *tmp_list,
+				const struct pnfs_layout_range *return_range,
+				u32 seq)
+{
+	struct pnfs_layout_segment *lseg, *next;
+	int remaining = 0;
+
+	dprintk("%s:Begin lo %p\n", __func__, lo);
+
+	assert_spin_locked(&lo->plh_inode->i_lock);
+
+	if (test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags))
+		tmp_list = &lo->plh_return_segs;
+
+	list_for_each_entry_safe(lseg, next, &lo->plh_segs, pls_list)
+		if (pnfs_match_lseg_recall(lseg, return_range, seq)) {
+			dprintk("%s: marking lseg %p iomode %d "
+				"offset %llu length %llu\n", __func__,
+				lseg, lseg->pls_range.iomode,
+				lseg->pls_range.offset,
+				lseg->pls_range.length);
+			if (test_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags))
+				tmp_list = &lo->plh_return_segs;
+			if (mark_lseg_invalid(lseg, tmp_list))
+				continue;
+			remaining++;
+			set_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags);
+		}
+
+	if (remaining) {
+		pnfs_set_plh_return_info(lo, return_range->iomode, seq);
+		return -EBUSY;
+	}
+
+	if (!list_empty(&lo->plh_return_segs)) {
+		pnfs_set_plh_return_info(lo, return_range->iomode, seq);
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+void pnfs_error_mark_layout_for_return(struct inode *inode,
+				       struct pnfs_layout_segment *lseg)
+{
+	struct pnfs_layout_hdr *lo = NFS_I(inode)->layout;
+	struct pnfs_layout_range range = {
+		.iomode = lseg->pls_range.iomode,
+		.offset = 0,
+		.length = NFS4_MAX_UINT64,
+	};
+	bool return_now = false;
+
+	spin_lock(&inode->i_lock);
+	if (!pnfs_layout_is_valid(lo)) {
+		spin_unlock(&inode->i_lock);
+		return;
+	}
+	pnfs_set_plh_return_info(lo, range.iomode, 0);
+	/*
+	 * mark all matching lsegs so that we are sure to have no live
+	 * segments at hand when sending layoutreturn. See pnfs_put_lseg()
+	 * for how it works.
+	 */
+	if (pnfs_mark_matching_lsegs_return(lo, &lo->plh_return_segs, &range, 0) != -EBUSY) {
+		nfs4_stateid stateid;
+		enum pnfs_iomode iomode;
+
+		return_now = pnfs_prepare_layoutreturn(lo, &stateid, &iomode);
+		spin_unlock(&inode->i_lock);
+		if (return_now)
+			pnfs_send_layoutreturn(lo, &stateid, iomode, false);
+	} else {
+		spin_unlock(&inode->i_lock);
+		nfs_commit_inode(inode, 0);
+	}
+}
+EXPORT_SYMBOL_GPL(pnfs_error_mark_layout_for_return);
+
+void
+pnfs_generic_pg_check_layout(struct nfs_pageio_descriptor *pgio)
+{
+	if (pgio->pg_lseg == NULL ||
+	    test_bit(NFS_LSEG_VALID, &pgio->pg_lseg->pls_flags))
+		return;
+	pnfs_put_lseg(pgio->pg_lseg);
+	pgio->pg_lseg = NULL;
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_check_layout);
+
+/*
+ * Check for any intersection between the request and the pgio->pg_lseg,
+ * and if none, put this pgio->pg_lseg away.
+ */
+static void
+pnfs_generic_pg_check_range(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
+{
+	if (pgio->pg_lseg && !pnfs_lseg_request_intersecting(pgio->pg_lseg, req)) {
+		pnfs_put_lseg(pgio->pg_lseg);
+		pgio->pg_lseg = NULL;
+	}
+}
+
+void
+pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
+{
+	u64 rd_size = req->wb_bytes;
+
+	pnfs_generic_pg_check_layout(pgio);
+	pnfs_generic_pg_check_range(pgio, req);
+	if (pgio->pg_lseg == NULL) {
+		if (pgio->pg_dreq == NULL)
+			rd_size = i_size_read(pgio->pg_inode) - req_offset(req);
+		else
+			rd_size = nfs_dreq_bytes_left(pgio->pg_dreq);
+
+		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
+						   req->wb_context,
+						   req_offset(req),
+						   rd_size,
+						   IOMODE_READ,
+						   false,
+						   GFP_KERNEL);
+		if (IS_ERR(pgio->pg_lseg)) {
+			pgio->pg_error = PTR_ERR(pgio->pg_lseg);
+			pgio->pg_lseg = NULL;
+			return;
+		}
+	}
+	/* If no lseg, fall back to read through mds */
+	if (pgio->pg_lseg == NULL)
+		nfs_pageio_reset_read_mds(pgio);
+
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_read);
+
+void
+pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio,
+			   struct nfs_page *req, u64 wb_size)
+{
+	pnfs_generic_pg_check_layout(pgio);
+	pnfs_generic_pg_check_range(pgio, req);
+	if (pgio->pg_lseg == NULL) {
+		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
+						   req->wb_context,
+						   req_offset(req),
+						   wb_size,
+						   IOMODE_RW,
+						   false,
+						   GFP_NOFS);
+		if (IS_ERR(pgio->pg_lseg)) {
+			pgio->pg_error = PTR_ERR(pgio->pg_lseg);
+			pgio->pg_lseg = NULL;
+			return;
+		}
+	}
+	/* If no lseg, fall back to write through mds */
+	if (pgio->pg_lseg == NULL)
+		nfs_pageio_reset_write_mds(pgio);
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_write);
+
+void
+pnfs_generic_pg_cleanup(struct nfs_pageio_descriptor *desc)
+{
+	if (desc->pg_lseg) {
+		pnfs_put_lseg(desc->pg_lseg);
+		desc->pg_lseg = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_cleanup);
+
+/*
+ * Return 0 if @req cannot be coalesced into @pgio, otherwise return the number
+ * of bytes (maximum @req->wb_bytes) that can be coalesced.
+ */
+size_t
+pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio,
+		     struct nfs_page *prev, struct nfs_page *req)
+{
+	unsigned int size;
+	u64 seg_end, req_start, seg_left;
+
+	size = nfs_generic_pg_test(pgio, prev, req);
+	if (!size)
+		return 0;
+
+	/*
+	 * 'size' contains the number of bytes left in the current page (up
+	 * to the original size asked for in @req->wb_bytes).
+	 *
+	 * Calculate how many bytes are left in the layout segment
+	 * and if there are less bytes than 'size', return that instead.
+	 *
+	 * Please also note that 'end_offset' is actually the offset of the
+	 * first byte that lies outside the pnfs_layout_range. FIXME?
+	 *
+	 */
+	if (pgio->pg_lseg) {
+		seg_end = pnfs_end_offset(pgio->pg_lseg->pls_range.offset,
+				     pgio->pg_lseg->pls_range.length);
+		req_start = req_offset(req);
+
+		/* start of request is past the last byte of this segment */
+		if (req_start >= seg_end)
+			return 0;
+
+		/* adjust 'size' iff there are fewer bytes left in the
+		 * segment than what nfs_generic_pg_test returned */
+		seg_left = seg_end - req_start;
+		if (seg_left < size)
+			size = (unsigned int)seg_left;
+	}
+
+	return size;
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_test);
+
+int pnfs_write_done_resend_to_mds(struct nfs_pgio_header *hdr)
+{
+	struct nfs_pageio_descriptor pgio;
+
+	/* Resend all requests through the MDS */
+	nfs_pageio_init_write(&pgio, hdr->inode, FLUSH_STABLE, true,
+			      hdr->completion_ops);
+	set_bit(NFS_CONTEXT_RESEND_WRITES, &hdr->args.context->flags);
+	return nfs_pageio_resend(&pgio, hdr);
+}
+EXPORT_SYMBOL_GPL(pnfs_write_done_resend_to_mds);
+
+static void pnfs_ld_handle_write_error(struct nfs_pgio_header *hdr)
+{
+
+	dprintk("pnfs write error = %d\n", hdr->pnfs_error);
+	if (NFS_SERVER(hdr->inode)->pnfs_curr_ld->flags &
+	    PNFS_LAYOUTRET_ON_ERROR) {
+		pnfs_return_layout(hdr->inode);
+	}
+	if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags))
+		hdr->task.tk_status = pnfs_write_done_resend_to_mds(hdr);
+}
+
+/*
+ * Called by non rpc-based layout drivers
+ */
+void pnfs_ld_write_done(struct nfs_pgio_header *hdr)
+{
+	if (likely(!hdr->pnfs_error)) {
+		pnfs_set_layoutcommit(hdr->inode, hdr->lseg,
+				hdr->mds_offset + hdr->res.count);
+		hdr->mds_ops->rpc_call_done(&hdr->task, hdr);
+	}
+	trace_nfs4_pnfs_write(hdr, hdr->pnfs_error);
+	if (unlikely(hdr->pnfs_error))
+		pnfs_ld_handle_write_error(hdr);
+	hdr->mds_ops->rpc_release(hdr);
+}
+EXPORT_SYMBOL_GPL(pnfs_ld_write_done);
+
+static void
+pnfs_write_through_mds(struct nfs_pageio_descriptor *desc,
+		struct nfs_pgio_header *hdr)
+{
+	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
+
+	if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
+		list_splice_tail_init(&hdr->pages, &mirror->pg_list);
+		nfs_pageio_reset_write_mds(desc);
+		mirror->pg_recoalesce = 1;
+	}
+	hdr->completion_ops->completion(hdr);
+}
+
+static enum pnfs_try_status
+pnfs_try_to_write_data(struct nfs_pgio_header *hdr,
+			const struct rpc_call_ops *call_ops,
+			struct pnfs_layout_segment *lseg,
+			int how)
+{
+	struct inode *inode = hdr->inode;
+	enum pnfs_try_status trypnfs;
+	struct nfs_server *nfss = NFS_SERVER(inode);
+
+	hdr->mds_ops = call_ops;
+
+	dprintk("%s: Writing ino:%lu %u@%llu (how %d)\n", __func__,
+		inode->i_ino, hdr->args.count, hdr->args.offset, how);
+	trypnfs = nfss->pnfs_curr_ld->write_pagelist(hdr, how);
+	if (trypnfs != PNFS_NOT_ATTEMPTED)
+		nfs_inc_stats(inode, NFSIOS_PNFS_WRITE);
+	dprintk("%s End (trypnfs:%d)\n", __func__, trypnfs);
+	return trypnfs;
+}
+
+static void
+pnfs_do_write(struct nfs_pageio_descriptor *desc,
+	      struct nfs_pgio_header *hdr, int how)
+{
+	const struct rpc_call_ops *call_ops = desc->pg_rpc_callops;
+	struct pnfs_layout_segment *lseg = desc->pg_lseg;
+	enum pnfs_try_status trypnfs;
+
+	trypnfs = pnfs_try_to_write_data(hdr, call_ops, lseg, how);
+	switch (trypnfs) {
+	case PNFS_NOT_ATTEMPTED:
+		pnfs_write_through_mds(desc, hdr);
+	case PNFS_ATTEMPTED:
+		break;
+	case PNFS_TRY_AGAIN:
+		/* cleanup hdr and prepare to redo pnfs */
+		if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
+			struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
+			list_splice_init(&hdr->pages, &mirror->pg_list);
+			mirror->pg_recoalesce = 1;
+		}
+		hdr->mds_ops->rpc_release(hdr);
+	}
+}
+
+static void pnfs_writehdr_free(struct nfs_pgio_header *hdr)
+{
+	pnfs_put_lseg(hdr->lseg);
+	nfs_pgio_header_free(hdr);
+}
+
+int
+pnfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
+{
+	struct nfs_pgio_header *hdr;
+	int ret;
+
+	hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
+	if (!hdr) {
+		desc->pg_error = -ENOMEM;
+		return desc->pg_error;
+	}
+	nfs_pgheader_init(desc, hdr, pnfs_writehdr_free);
+
+	hdr->lseg = pnfs_get_lseg(desc->pg_lseg);
+	ret = nfs_generic_pgio(desc, hdr);
+	if (!ret)
+		pnfs_do_write(desc, hdr, desc->pg_ioflags);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_writepages);
+
+int pnfs_read_done_resend_to_mds(struct nfs_pgio_header *hdr)
+{
+	struct nfs_pageio_descriptor pgio;
+
+	/* Resend all requests through the MDS */
+	nfs_pageio_init_read(&pgio, hdr->inode, true, hdr->completion_ops);
+	return nfs_pageio_resend(&pgio, hdr);
+}
+EXPORT_SYMBOL_GPL(pnfs_read_done_resend_to_mds);
+
+static void pnfs_ld_handle_read_error(struct nfs_pgio_header *hdr)
+{
+	dprintk("pnfs read error = %d\n", hdr->pnfs_error);
+	if (NFS_SERVER(hdr->inode)->pnfs_curr_ld->flags &
+	    PNFS_LAYOUTRET_ON_ERROR) {
+		pnfs_return_layout(hdr->inode);
+	}
+	if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags))
+		hdr->task.tk_status = pnfs_read_done_resend_to_mds(hdr);
+}
+
+/*
+ * Called by non rpc-based layout drivers
+ */
+void pnfs_ld_read_done(struct nfs_pgio_header *hdr)
+{
+	if (likely(!hdr->pnfs_error))
+		hdr->mds_ops->rpc_call_done(&hdr->task, hdr);
+	trace_nfs4_pnfs_read(hdr, hdr->pnfs_error);
+	if (unlikely(hdr->pnfs_error))
+		pnfs_ld_handle_read_error(hdr);
+	hdr->mds_ops->rpc_release(hdr);
+}
+EXPORT_SYMBOL_GPL(pnfs_ld_read_done);
+
+static void
+pnfs_read_through_mds(struct nfs_pageio_descriptor *desc,
+		struct nfs_pgio_header *hdr)
+{
+	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
+
+	if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
+		list_splice_tail_init(&hdr->pages, &mirror->pg_list);
+		nfs_pageio_reset_read_mds(desc);
+		mirror->pg_recoalesce = 1;
+	}
+	hdr->completion_ops->completion(hdr);
+}
+
+/*
+ * Call the appropriate parallel I/O subsystem read function.
+ */
+static enum pnfs_try_status
+pnfs_try_to_read_data(struct nfs_pgio_header *hdr,
+		       const struct rpc_call_ops *call_ops,
+		       struct pnfs_layout_segment *lseg)
+{
+	struct inode *inode = hdr->inode;
+	struct nfs_server *nfss = NFS_SERVER(inode);
+	enum pnfs_try_status trypnfs;
+
+	hdr->mds_ops = call_ops;
+
+	dprintk("%s: Reading ino:%lu %u@%llu\n",
+		__func__, inode->i_ino, hdr->args.count, hdr->args.offset);
+
+	trypnfs = nfss->pnfs_curr_ld->read_pagelist(hdr);
+	if (trypnfs != PNFS_NOT_ATTEMPTED)
+		nfs_inc_stats(inode, NFSIOS_PNFS_READ);
+	dprintk("%s End (trypnfs:%d)\n", __func__, trypnfs);
+	return trypnfs;
+}
+
+/* Resend all requests through pnfs. */
+void pnfs_read_resend_pnfs(struct nfs_pgio_header *hdr)
+{
+	struct nfs_pageio_descriptor pgio;
+
+	if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
+		/* Prevent deadlocks with layoutreturn! */
+		pnfs_put_lseg(hdr->lseg);
+		hdr->lseg = NULL;
+
+		nfs_pageio_init_read(&pgio, hdr->inode, false,
+					hdr->completion_ops);
+		hdr->task.tk_status = nfs_pageio_resend(&pgio, hdr);
+	}
+}
+EXPORT_SYMBOL_GPL(pnfs_read_resend_pnfs);
+
+static void
+pnfs_do_read(struct nfs_pageio_descriptor *desc, struct nfs_pgio_header *hdr)
+{
+	const struct rpc_call_ops *call_ops = desc->pg_rpc_callops;
+	struct pnfs_layout_segment *lseg = desc->pg_lseg;
+	enum pnfs_try_status trypnfs;
+
+	trypnfs = pnfs_try_to_read_data(hdr, call_ops, lseg);
+	switch (trypnfs) {
+	case PNFS_NOT_ATTEMPTED:
+		pnfs_read_through_mds(desc, hdr);
+	case PNFS_ATTEMPTED:
+		break;
+	case PNFS_TRY_AGAIN:
+		/* cleanup hdr and prepare to redo pnfs */
+		if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
+			struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
+			list_splice_init(&hdr->pages, &mirror->pg_list);
+			mirror->pg_recoalesce = 1;
+		}
+		hdr->mds_ops->rpc_release(hdr);
+	}
+}
+
+static void pnfs_readhdr_free(struct nfs_pgio_header *hdr)
+{
+	pnfs_put_lseg(hdr->lseg);
+	nfs_pgio_header_free(hdr);
+}
+
+int
+pnfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc)
+{
+	struct nfs_pgio_header *hdr;
+	int ret;
+
+	hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
+	if (!hdr) {
+		desc->pg_error = -ENOMEM;
+		return desc->pg_error;
+	}
+	nfs_pgheader_init(desc, hdr, pnfs_readhdr_free);
+	hdr->lseg = pnfs_get_lseg(desc->pg_lseg);
+	ret = nfs_generic_pgio(desc, hdr);
+	if (!ret)
+		pnfs_do_read(desc, hdr);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_readpages);
+
+static void pnfs_clear_layoutcommitting(struct inode *inode)
+{
+	unsigned long *bitlock = &NFS_I(inode)->flags;
+
+	clear_bit_unlock(NFS_INO_LAYOUTCOMMITTING, bitlock);
+	smp_mb__after_atomic();
+	wake_up_bit(bitlock, NFS_INO_LAYOUTCOMMITTING);
+}
+
+/*
+ * There can be multiple RW segments.
+ */
+static void pnfs_list_write_lseg(struct inode *inode, struct list_head *listp)
+{
+	struct pnfs_layout_segment *lseg;
+
+	list_for_each_entry(lseg, &NFS_I(inode)->layout->plh_segs, pls_list) {
+		if (lseg->pls_range.iomode == IOMODE_RW &&
+		    test_and_clear_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags))
+			list_add(&lseg->pls_lc_list, listp);
+	}
+}
+
+static void pnfs_list_write_lseg_done(struct inode *inode, struct list_head *listp)
+{
+	struct pnfs_layout_segment *lseg, *tmp;
+
+	/* Matched by references in pnfs_set_layoutcommit */
+	list_for_each_entry_safe(lseg, tmp, listp, pls_lc_list) {
+		list_del_init(&lseg->pls_lc_list);
+		pnfs_put_lseg(lseg);
+	}
+
+	pnfs_clear_layoutcommitting(inode);
+}
+
+void pnfs_set_lo_fail(struct pnfs_layout_segment *lseg)
+{
+	pnfs_layout_io_set_failed(lseg->pls_layout, lseg->pls_range.iomode);
+}
+EXPORT_SYMBOL_GPL(pnfs_set_lo_fail);
+
+void
+pnfs_set_layoutcommit(struct inode *inode, struct pnfs_layout_segment *lseg,
+		loff_t end_pos)
+{
+	struct nfs_inode *nfsi = NFS_I(inode);
+	bool mark_as_dirty = false;
+
+	spin_lock(&inode->i_lock);
+	if (!test_and_set_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags)) {
+		nfsi->layout->plh_lwb = end_pos;
+		mark_as_dirty = true;
+		dprintk("%s: Set layoutcommit for inode %lu ",
+			__func__, inode->i_ino);
+	} else if (end_pos > nfsi->layout->plh_lwb)
+		nfsi->layout->plh_lwb = end_pos;
+	if (!test_and_set_bit(NFS_LSEG_LAYOUTCOMMIT, &lseg->pls_flags)) {
+		/* references matched in nfs4_layoutcommit_release */
+		pnfs_get_lseg(lseg);
+	}
+	spin_unlock(&inode->i_lock);
+	dprintk("%s: lseg %p end_pos %llu\n",
+		__func__, lseg, nfsi->layout->plh_lwb);
+
+	/* if pnfs_layoutcommit_inode() runs between inode locks, the next one
+	 * will be a noop because NFS_INO_LAYOUTCOMMIT will not be set */
+	if (mark_as_dirty)
+		mark_inode_dirty_sync(inode);
+}
+EXPORT_SYMBOL_GPL(pnfs_set_layoutcommit);
+
+void pnfs_cleanup_layoutcommit(struct nfs4_layoutcommit_data *data)
+{
+	struct nfs_server *nfss = NFS_SERVER(data->args.inode);
+
+	if (nfss->pnfs_curr_ld->cleanup_layoutcommit)
+		nfss->pnfs_curr_ld->cleanup_layoutcommit(data);
+	pnfs_list_write_lseg_done(data->args.inode, &data->lseg_list);
+}
+
+/*
+ * For the LAYOUT4_NFSV4_1_FILES layout type, NFS_DATA_SYNC WRITEs and
+ * NFS_UNSTABLE WRITEs with a COMMIT to data servers must store enough
+ * data to disk to allow the server to recover the data if it crashes.
+ * LAYOUTCOMMIT is only needed when the NFL4_UFLG_COMMIT_THRU_MDS flag
+ * is off, and a COMMIT is sent to a data server, or
+ * if WRITEs to a data server return NFS_DATA_SYNC.
+ */
+int
+pnfs_layoutcommit_inode(struct inode *inode, bool sync)
+{
+	struct pnfs_layoutdriver_type *ld = NFS_SERVER(inode)->pnfs_curr_ld;
+	struct nfs4_layoutcommit_data *data;
+	struct nfs_inode *nfsi = NFS_I(inode);
+	loff_t end_pos;
+	int status;
+
+	if (!pnfs_layoutcommit_outstanding(inode))
+		return 0;
+
+	dprintk("--> %s inode %lu\n", __func__, inode->i_ino);
+
+	status = -EAGAIN;
+	if (test_and_set_bit(NFS_INO_LAYOUTCOMMITTING, &nfsi->flags)) {
+		if (!sync)
+			goto out;
+		status = wait_on_bit_lock_action(&nfsi->flags,
+				NFS_INO_LAYOUTCOMMITTING,
+				nfs_wait_bit_killable,
+				TASK_KILLABLE);
+		if (status)
+			goto out;
+	}
+
+	status = -ENOMEM;
+	/* Note kzalloc ensures data->res.seq_res.sr_slot == NULL */
+	data = kzalloc(sizeof(*data), GFP_NOFS);
+	if (!data)
+		goto clear_layoutcommitting;
+
+	status = 0;
+	spin_lock(&inode->i_lock);
+	if (!test_and_clear_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags))
+		goto out_unlock;
+
+	INIT_LIST_HEAD(&data->lseg_list);
+	pnfs_list_write_lseg(inode, &data->lseg_list);
+
+	end_pos = nfsi->layout->plh_lwb;
+
+	nfs4_stateid_copy(&data->args.stateid, &nfsi->layout->plh_stateid);
+	spin_unlock(&inode->i_lock);
+
+	data->args.inode = inode;
+	data->cred = get_rpccred(nfsi->layout->plh_lc_cred);
+	nfs_fattr_init(&data->fattr);
+	data->args.bitmask = NFS_SERVER(inode)->cache_consistency_bitmask;
+	data->res.fattr = &data->fattr;
+	if (end_pos != 0)
+		data->args.lastbytewritten = end_pos - 1;
+	else
+		data->args.lastbytewritten = U64_MAX;
+	data->res.server = NFS_SERVER(inode);
+
+	if (ld->prepare_layoutcommit) {
+		status = ld->prepare_layoutcommit(&data->args);
+		if (status) {
+			put_rpccred(data->cred);
+			spin_lock(&inode->i_lock);
+			set_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags);
+			if (end_pos > nfsi->layout->plh_lwb)
+				nfsi->layout->plh_lwb = end_pos;
+			goto out_unlock;
+		}
+	}
+
+
+	status = nfs4_proc_layoutcommit(data, sync);
+out:
+	if (status)
+		mark_inode_dirty_sync(inode);
+	dprintk("<-- %s status %d\n", __func__, status);
+	return status;
+out_unlock:
+	spin_unlock(&inode->i_lock);
+	kfree(data);
+clear_layoutcommitting:
+	pnfs_clear_layoutcommitting(inode);
+	goto out;
+}
+EXPORT_SYMBOL_GPL(pnfs_layoutcommit_inode);
+
+int
+pnfs_generic_sync(struct inode *inode, bool datasync)
+{
+	return pnfs_layoutcommit_inode(inode, true);
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_sync);
+
+struct nfs4_threshold *pnfs_mdsthreshold_alloc(void)
+{
+	struct nfs4_threshold *thp;
+
+	thp = kzalloc(sizeof(*thp), GFP_NOFS);
+	if (!thp) {
+		dprintk("%s mdsthreshold allocation failed\n", __func__);
+		return NULL;
+	}
+	return thp;
+}
+
+#if IS_ENABLED(CONFIG_NFS_V4_2)
+int
+pnfs_report_layoutstat(struct inode *inode, gfp_t gfp_flags)
+{
+	struct pnfs_layoutdriver_type *ld = NFS_SERVER(inode)->pnfs_curr_ld;
+	struct nfs_server *server = NFS_SERVER(inode);
+	struct nfs_inode *nfsi = NFS_I(inode);
+	struct nfs42_layoutstat_data *data;
+	struct pnfs_layout_hdr *hdr;
+	int status = 0;
+
+	if (!pnfs_enabled_sb(server) || !ld->prepare_layoutstats)
+		goto out;
+
+	if (!nfs_server_capable(inode, NFS_CAP_LAYOUTSTATS))
+		goto out;
+
+	if (test_and_set_bit(NFS_INO_LAYOUTSTATS, &nfsi->flags))
+		goto out;
+
+	spin_lock(&inode->i_lock);
+	if (!NFS_I(inode)->layout) {
+		spin_unlock(&inode->i_lock);
+		goto out_clear_layoutstats;
+	}
+	hdr = NFS_I(inode)->layout;
+	pnfs_get_layout_hdr(hdr);
+	spin_unlock(&inode->i_lock);
+
+	data = kzalloc(sizeof(*data), gfp_flags);
+	if (!data) {
+		status = -ENOMEM;
+		goto out_put;
+	}
+
+	data->args.fh = NFS_FH(inode);
+	data->args.inode = inode;
+	status = ld->prepare_layoutstats(&data->args);
+	if (status)
+		goto out_free;
+
+	status = nfs42_proc_layoutstats_generic(NFS_SERVER(inode), data);
+
+out:
+	dprintk("%s returns %d\n", __func__, status);
+	return status;
+
+out_free:
+	kfree(data);
+out_put:
+	pnfs_put_layout_hdr(hdr);
+out_clear_layoutstats:
+	smp_mb__before_atomic();
+	clear_bit(NFS_INO_LAYOUTSTATS, &nfsi->flags);
+	smp_mb__after_atomic();
+	goto out;
+}
+EXPORT_SYMBOL_GPL(pnfs_report_layoutstat);
+#endif
+
+unsigned int layoutstats_timer;
+module_param(layoutstats_timer, uint, 0644);
+EXPORT_SYMBOL_GPL(layoutstats_timer);