--- zzzz-none-000/linux-3.10.107/fs/nfs/pnfs.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/fs/nfs/pnfs.c	2021-02-04 17:41:59.000000000 +0000
@@ -33,6 +33,9 @@
 #include "internal.h"
 #include "pnfs.h"
 #include "iostat.h"
+#include "nfs4trace.h"
+#include "delegation.h"
+#include "nfs42.h"
 
 #define NFSDBG_FACILITY		NFSDBG_PNFS
 #define PNFS_LAYOUTGET_RETRY_TIMEOUT (120*HZ)
@@ -49,6 +52,10 @@
  */
 static LIST_HEAD(pnfs_modules_tbl);
 
+static int
+pnfs_send_layoutreturn(struct pnfs_layout_hdr *lo, nfs4_stateid stateid,
+		       enum pnfs_iomode iomode, bool sync);
+
 /* Return the registered pnfs layout driver module matching given id */
 static struct pnfs_layoutdriver_type *
 find_pnfs_driver_locked(u32 id)
@@ -237,6 +244,8 @@
 	struct inode *inode = lo->plh_inode;
 
 	if (atomic_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);
 		spin_unlock(&inode->i_lock);
 		pnfs_free_layout_hdr(lo);
@@ -336,6 +345,61 @@
 	rpc_wake_up(&NFS_SERVER(inode)->roc_rpcwaitq);
 }
 
+/* Return true if layoutreturn is needed */
+static bool
+pnfs_layout_need_return(struct pnfs_layout_hdr *lo,
+			struct pnfs_layout_segment *lseg)
+{
+	struct pnfs_layout_segment *s;
+
+	if (!test_and_clear_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags))
+		return false;
+
+	list_for_each_entry(s, &lo->plh_segs, pls_list)
+		if (s != lseg && test_bit(NFS_LSEG_LAYOUTRETURN, &s->pls_flags))
+			return false;
+
+	return true;
+}
+
+static bool
+pnfs_prepare_layoutreturn(struct pnfs_layout_hdr *lo)
+{
+	/* Serialise LAYOUTGET/LAYOUTRETURN */
+	if (atomic_read(&lo->plh_outstanding) != 0)
+		return false;
+	if (test_and_set_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
+		return false;
+	lo->plh_return_iomode = 0;
+	pnfs_get_layout_hdr(lo);
+	clear_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE, &lo->plh_flags);
+	return true;
+}
+
+static void pnfs_layoutreturn_before_put_lseg(struct pnfs_layout_segment *lseg,
+		struct pnfs_layout_hdr *lo, struct inode *inode)
+{
+	lo = lseg->pls_layout;
+	inode = lo->plh_inode;
+
+	spin_lock(&inode->i_lock);
+	if (pnfs_layout_need_return(lo, lseg)) {
+		nfs4_stateid stateid;
+		enum pnfs_iomode iomode;
+		bool send;
+
+		stateid = lo->plh_stateid;
+		iomode = lo->plh_return_iomode;
+		send = pnfs_prepare_layoutreturn(lo);
+		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);
+}
+
 void
 pnfs_put_lseg(struct pnfs_layout_segment *lseg)
 {
@@ -348,9 +412,22 @@
 	dprintk("%s: lseg %p ref %d valid %d\n", __func__, lseg,
 		atomic_read(&lseg->pls_refcount),
 		test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
+
+	/* Handle the case where refcount != 1 */
+	if (atomic_add_unless(&lseg->pls_refcount, -1, 1))
+		return;
+
 	lo = lseg->pls_layout;
 	inode = lo->plh_inode;
+	/* Do we need a layoutreturn? */
+	if (test_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags))
+		pnfs_layoutreturn_before_put_lseg(lseg, lo, inode);
+
 	if (atomic_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);
 		spin_unlock(&inode->i_lock);
@@ -360,7 +437,47 @@
 }
 EXPORT_SYMBOL_GPL(pnfs_put_lseg);
 
-static inline u64
+static void pnfs_free_lseg_async_work(struct work_struct *work)
+{
+	struct pnfs_layout_segment *lseg;
+	struct pnfs_layout_hdr *lo;
+
+	lseg = container_of(work, struct pnfs_layout_segment, pls_work);
+	lo = lseg->pls_layout;
+
+	pnfs_free_lseg(lseg);
+	pnfs_put_layout_hdr(lo);
+}
+
+static void pnfs_free_lseg_async(struct pnfs_layout_segment *lseg)
+{
+	INIT_WORK(&lseg->pls_work, pnfs_free_lseg_async_work);
+	schedule_work(&lseg->pls_work);
+}
+
+void
+pnfs_put_lseg_locked(struct pnfs_layout_segment *lseg)
+{
+	if (!lseg)
+		return;
+
+	assert_spin_locked(&lseg->pls_layout->plh_inode->i_lock);
+
+	dprintk("%s: lseg %p ref %d valid %d\n", __func__, lseg,
+		atomic_read(&lseg->pls_refcount),
+		test_bit(NFS_LSEG_VALID, &lseg->pls_flags));
+	if (atomic_dec_and_test(&lseg->pls_refcount)) {
+		struct pnfs_layout_hdr *lo = lseg->pls_layout;
+		if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags))
+			return;
+		pnfs_get_layout_hdr(lo);
+		pnfs_layout_remove_lseg(lo, lseg);
+		pnfs_free_lseg_async(lseg);
+	}
+}
+EXPORT_SYMBOL_GPL(pnfs_put_lseg_locked);
+
+static u64
 end_offset(u64 start, u64 len)
 {
 	u64 end;
@@ -376,9 +493,9 @@
  *           start2           end2
  *           [----------------)
  */
-static inline int
-lo_seg_contained(struct pnfs_layout_range *l1,
-		 struct pnfs_layout_range *l2)
+static bool
+pnfs_lseg_range_contained(const struct pnfs_layout_range *l1,
+		 const struct pnfs_layout_range *l2)
 {
 	u64 start1 = l1->offset;
 	u64 end1 = end_offset(start1, l1->length);
@@ -395,9 +512,9 @@
  *                              start2           end2
  *                              [----------------)
  */
-static inline int
-lo_seg_intersecting(struct pnfs_layout_range *l1,
-		    struct pnfs_layout_range *l2)
+static bool
+pnfs_lseg_range_intersecting(const struct pnfs_layout_range *l1,
+		    const struct pnfs_layout_range *l2)
 {
 	u64 start1 = l1->offset;
 	u64 end1 = end_offset(start1, l1->length);
@@ -409,12 +526,12 @@
 }
 
 static bool
-should_free_lseg(struct pnfs_layout_range *lseg_range,
-		 struct pnfs_layout_range *recall_range)
+should_free_lseg(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) &&
-	       lo_seg_intersecting(lseg_range, recall_range);
+	       pnfs_lseg_range_intersecting(lseg_range, recall_range);
 }
 
 static bool pnfs_lseg_dec_and_remove_zero(struct pnfs_layout_segment *lseg,
@@ -504,6 +621,7 @@
 		pnfs_get_layout_hdr(lo);
 		pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RO_FAILED);
 		pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RW_FAILED);
+		pnfs_clear_retry_layoutget(lo);
 		spin_unlock(&nfsi->vfs_inode.i_lock);
 		pnfs_free_lseg_list(&tmp_list);
 		pnfs_put_layout_hdr(lo);
@@ -576,6 +694,9 @@
 		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);
 		lo->plh_block_lgets++; /* permanently block new LAYOUTGETs */
@@ -661,7 +782,7 @@
  */
 static bool pnfs_seqid_is_newer(u32 s1, u32 s2)
 {
-	return (s32)s1 - (s32)s2 > 0;
+	return (s32)(s1 - s2) > 0;
 }
 
 /* update lo->plh_stateid with new if is more recent */
@@ -700,27 +821,27 @@
 
 /* lget is set to 1 if called from inside send_layoutget call chain */
 static bool
-pnfs_layoutgets_blocked(const struct pnfs_layout_hdr *lo, int lget)
+pnfs_layoutgets_blocked(const struct pnfs_layout_hdr *lo)
 {
 	return lo->plh_block_lgets ||
-		test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags) ||
-		(list_empty(&lo->plh_segs) &&
-		 (atomic_read(&lo->plh_outstanding) > lget));
+		test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags);
 }
 
 int
 pnfs_choose_layoutget_stateid(nfs4_stateid *dst, struct pnfs_layout_hdr *lo,
+			      struct pnfs_layout_range *range,
 			      struct nfs4_state *open_state)
 {
 	int status = 0;
 
 	dprintk("--> %s\n", __func__);
 	spin_lock(&lo->plh_inode->i_lock);
-	if (pnfs_layoutgets_blocked(lo, 1)) {
+	if (pnfs_layoutgets_blocked(lo)) {
 		status = -EAGAIN;
 	} else if (!nfs4_valid_open_stateid(open_state)) {
 		status = -EBADF;
-	} else if (list_empty(&lo->plh_segs)) {
+	} else if (list_empty(&lo->plh_segs) ||
+		   test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags)) {
 		int seq;
 
 		do {
@@ -750,27 +871,42 @@
 	struct nfs_server *server = NFS_SERVER(ino);
 	struct nfs4_layoutget *lgp;
 	struct pnfs_layout_segment *lseg;
+	loff_t i_size;
 
 	dprintk("--> %s\n", __func__);
 
-	lgp = kzalloc(sizeof(*lgp), gfp_flags);
-	if (lgp == NULL)
-		return NULL;
+	/*
+	 * Synchronously retrieve layout information from server and
+	 * store in lseg. If we race with a concurrent seqid morphing
+	 * op, then re-send the LAYOUTGET.
+	 */
+	do {
+		lgp = kzalloc(sizeof(*lgp), gfp_flags);
+		if (lgp == NULL)
+			return NULL;
+
+		i_size = i_size_read(ino);
+
+		lgp->args.minlength = PAGE_CACHE_SIZE;
+		if (lgp->args.minlength > range->length)
+			lgp->args.minlength = range->length;
+		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;
+		lgp->args.range = *range;
+		lgp->args.type = server->pnfs_curr_ld->id;
+		lgp->args.inode = ino;
+		lgp->args.ctx = get_nfs_open_context(ctx);
+		lgp->gfp_flags = gfp_flags;
+		lgp->cred = lo->plh_lc_cred;
 
-	lgp->args.minlength = PAGE_CACHE_SIZE;
-	if (lgp->args.minlength > range->length)
-		lgp->args.minlength = range->length;
-	lgp->args.maxcount = PNFS_LAYOUT_MAXSIZE;
-	lgp->args.range = *range;
-	lgp->args.type = server->pnfs_curr_ld->id;
-	lgp->args.inode = ino;
-	lgp->args.ctx = get_nfs_open_context(ctx);
-	lgp->gfp_flags = gfp_flags;
+		lseg = nfs4_proc_layoutget(lgp, gfp_flags);
+	} while (lseg == ERR_PTR(-EAGAIN));
 
-	/* Synchronously retrieve layout information from server and
-	 * store in lseg.
-	 */
-	lseg = nfs4_proc_layoutget(lgp, gfp_flags);
 	if (IS_ERR(lseg)) {
 		switch (PTR_ERR(lseg)) {
 		case -ENOMEM:
@@ -781,7 +917,9 @@
 			pnfs_layout_io_set_failed(lo, range->iomode);
 		}
 		return NULL;
-	}
+	} else
+		pnfs_layout_clear_fail_bit(lo,
+				pnfs_iomode_to_fail_bit(range->iomode));
 
 	return lseg;
 }
@@ -801,6 +939,48 @@
 	}
 }
 
+void pnfs_clear_layoutreturn_waitbit(struct pnfs_layout_hdr *lo)
+{
+	clear_bit_unlock(NFS_LAYOUT_RETURN, &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 int
+pnfs_send_layoutreturn(struct pnfs_layout_hdr *lo, nfs4_stateid stateid,
+		       enum pnfs_iomode iomode, bool sync)
+{
+	struct inode *ino = lo->plh_inode;
+	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;
+	}
+
+	lrp->args.stateid = stateid;
+	lrp->args.layout_type = NFS_SERVER(ino)->pnfs_curr_ld->id;
+	lrp->args.inode = ino;
+	lrp->args.range.iomode = iomode;
+	lrp->args.range.offset = 0;
+	lrp->args.range.length = NFS4_MAX_UINT64;
+	lrp->args.layout = lo;
+	lrp->clp = NFS_SERVER(ino)->nfs_client;
+	lrp->cred = lo->plh_lc_cred;
+
+	status = nfs4_proc_layoutreturn(lrp, sync);
+out:
+	dprintk("<-- %s status: %d\n", __func__, status);
+	return status;
+}
+
 /*
  * Initiates a LAYOUTRETURN(FILE), and removes the pnfs_layout_hdr
  * when the layout segment list is empty.
@@ -815,9 +995,9 @@
 	struct pnfs_layout_hdr *lo = NULL;
 	struct nfs_inode *nfsi = NFS_I(ino);
 	LIST_HEAD(tmp_list);
-	struct nfs4_layoutreturn *lrp;
 	nfs4_stateid stateid;
 	int status = 0, empty;
+	bool send;
 
 	dprintk("NFS: %s for inode %lu\n", __func__, ino->i_ino);
 
@@ -834,34 +1014,31 @@
 	empty = list_empty(&lo->plh_segs);
 	pnfs_clear_layoutcommit(ino, &tmp_list);
 	pnfs_mark_matching_lsegs_invalid(lo, &tmp_list, NULL);
+
+	if (NFS_SERVER(ino)->pnfs_curr_ld->return_range) {
+		struct pnfs_layout_range range = {
+			.iomode		= IOMODE_ANY,
+			.offset		= 0,
+			.length		= NFS4_MAX_UINT64,
+		};
+		NFS_SERVER(ino)->pnfs_curr_ld->return_range(lo, &range);
+	}
+
 	/* Don't send a LAYOUTRETURN if list was initially empty */
 	if (empty) {
 		spin_unlock(&ino->i_lock);
-		pnfs_put_layout_hdr(lo);
 		dprintk("NFS: %s no layout segments to return\n", __func__);
-		goto out;
+		goto out_put_layout_hdr;
 	}
-	lo->plh_block_lgets++;
+
+	set_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
+	send = pnfs_prepare_layoutreturn(lo);
 	spin_unlock(&ino->i_lock);
 	pnfs_free_lseg_list(&tmp_list);
-
-	lrp = kzalloc(sizeof(*lrp), GFP_KERNEL);
-	if (unlikely(lrp == NULL)) {
-		status = -ENOMEM;
-		spin_lock(&ino->i_lock);
-		lo->plh_block_lgets--;
-		spin_unlock(&ino->i_lock);
-		pnfs_put_layout_hdr(lo);
-		goto out;
-	}
-
-	lrp->args.stateid = stateid;
-	lrp->args.layout_type = NFS_SERVER(ino)->pnfs_curr_ld->id;
-	lrp->args.inode = ino;
-	lrp->args.layout = lo;
-	lrp->clp = NFS_SERVER(ino)->nfs_client;
-
-	status = nfs4_proc_layoutreturn(lrp);
+	if (send)
+		status = pnfs_send_layoutreturn(lo, stateid, IOMODE_ANY, true);
+out_put_layout_hdr:
+	pnfs_put_layout_hdr(lo);
 out:
 	dprintk("<-- %s status: %d\n", __func__, status);
 	return status;
@@ -897,32 +1074,61 @@
 
 bool pnfs_roc(struct inode *ino)
 {
+	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, *tmp;
+	nfs4_stateid stateid;
 	LIST_HEAD(tmp_list);
-	bool found = false;
+	bool found = false, layoutreturn = false, roc = false;
 
 	spin_lock(&ino->i_lock);
-	lo = NFS_I(ino)->layout;
-	if (!lo || !test_and_clear_bit(NFS_LAYOUT_ROC, &lo->plh_flags) ||
-	    test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags))
-		goto out_nolayout;
+	lo = nfsi->layout;
+	if (!lo || test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags))
+		goto out_noroc;
+
+	/* no roc if we hold a delegation */
+	if (nfs4_check_delegation(ino, FMODE_READ))
+		goto out_noroc;
+
+	list_for_each_entry(ctx, &nfsi->open_files, list) {
+		state = ctx->state;
+		/* Don't return layout if there is open file state */
+		if (state != NULL && state->state != 0)
+			goto out_noroc;
+	}
+
+	stateid = lo->plh_stateid;
+	/* always send layoutreturn if being marked so */
+	if (test_and_clear_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE,
+				   &lo->plh_flags))
+		layoutreturn = pnfs_prepare_layoutreturn(lo);
+
+	pnfs_clear_retry_layoutget(lo);
 	list_for_each_entry_safe(lseg, tmp, &lo->plh_segs, pls_list)
-		if (test_bit(NFS_LSEG_ROC, &lseg->pls_flags)) {
+		/* If we are sending layoutreturn, invalidate all valid lsegs */
+		if (layoutreturn || test_bit(NFS_LSEG_ROC, &lseg->pls_flags)) {
 			mark_lseg_invalid(lseg, &tmp_list);
 			found = true;
 		}
-	if (!found)
-		goto out_nolayout;
-	lo->plh_block_lgets++;
-	pnfs_get_layout_hdr(lo); /* matched in pnfs_roc_release */
-	spin_unlock(&ino->i_lock);
-	pnfs_free_lseg_list(&tmp_list);
-	return true;
+	/* ROC in two conditions:
+	 * 1. there are ROC lsegs
+	 * 2. we don't send layoutreturn
+	 */
+	if (found && !layoutreturn) {
+		/* lo ref dropped in pnfs_roc_release() */
+		pnfs_get_layout_hdr(lo);
+		roc = true;
+	}
 
-out_nolayout:
+out_noroc:
 	spin_unlock(&ino->i_lock);
-	return false;
+	pnfs_free_lseg_list(&tmp_list);
+	pnfs_layoutcommit_inode(ino, true);
+	if (layoutreturn)
+		pnfs_send_layoutreturn(lo, stateid, IOMODE_ANY, true);
+	return roc;
 }
 
 void pnfs_roc_release(struct inode *ino)
@@ -931,7 +1137,7 @@
 
 	spin_lock(&ino->i_lock);
 	lo = NFS_I(ino)->layout;
-	lo->plh_block_lgets--;
+	pnfs_clear_layoutreturn_waitbit(lo);
 	if (atomic_dec_and_test(&lo->plh_refcount)) {
 		pnfs_detach_layout_hdr(lo);
 		spin_unlock(&ino->i_lock);
@@ -949,23 +1155,16 @@
 	if (pnfs_seqid_is_newer(barrier, lo->plh_barrier))
 		lo->plh_barrier = barrier;
 	spin_unlock(&ino->i_lock);
+	trace_nfs4_layoutreturn_on_close(ino, 0);
 }
 
-bool pnfs_roc_drain(struct inode *ino, u32 *barrier, struct rpc_task *task)
+void pnfs_roc_get_barrier(struct inode *ino, u32 *barrier)
 {
 	struct nfs_inode *nfsi = NFS_I(ino);
 	struct pnfs_layout_hdr *lo;
-	struct pnfs_layout_segment *lseg;
 	u32 current_seqid;
-	bool found = false;
 
 	spin_lock(&ino->i_lock);
-	list_for_each_entry(lseg, &nfsi->layout->plh_segs, pls_list)
-		if (test_bit(NFS_LSEG_ROC, &lseg->pls_flags)) {
-			rpc_sleep_on(&NFS_SERVER(ino)->roc_rpcwaitq, task, NULL);
-			found = true;
-			goto out;
-		}
 	lo = nfsi->layout;
 	current_seqid = be32_to_cpu(lo->plh_stateid.seqid);
 
@@ -973,9 +1172,25 @@
 	 * a barrier, we choose the worst-case barrier.
 	 */
 	*barrier = current_seqid + atomic_read(&lo->plh_outstanding);
-out:
 	spin_unlock(&ino->i_lock);
-	return found;
+}
+
+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;
 }
 
 /*
@@ -984,8 +1199,8 @@
  * are seen first.
  */
 static s64
-cmp_layout(struct pnfs_layout_range *l1,
-	   struct pnfs_layout_range *l2)
+pnfs_lseg_range_cmp(const struct pnfs_layout_range *l1,
+	   const struct pnfs_layout_range *l2)
 {
 	s64 d;
 
@@ -1003,16 +1218,41 @@
 	return (int)(l1->iomode == IOMODE_READ) - (int)(l2->iomode == IOMODE_READ);
 }
 
-static void
-pnfs_layout_insert_lseg(struct pnfs_layout_hdr *lo,
-		   struct pnfs_layout_segment *lseg)
+static bool
+pnfs_lseg_range_is_after(const struct pnfs_layout_range *l1,
+		const struct pnfs_layout_range *l2)
 {
-	struct pnfs_layout_segment *lp;
+	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(lp, &lo->plh_segs, pls_list) {
-		if (cmp_layout(&lseg->pls_range, &lp->pls_range) > 0)
+	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 "
@@ -1034,6 +1274,24 @@
 
 	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,
@@ -1050,7 +1308,7 @@
 	INIT_LIST_HEAD(&lo->plh_segs);
 	INIT_LIST_HEAD(&lo->plh_bulk_destroy);
 	lo->plh_inode = ino;
-	lo->plh_lc_cred = get_rpccred(ctx->state->owner->so_cred);
+	lo->plh_lc_cred = get_rpccred(ctx->cred);
 	return lo;
 }
 
@@ -1091,21 +1349,21 @@
  * READ		READ	true
  * READ		RW	true
  */
-static int
-is_matching_lseg(struct pnfs_layout_range *ls_range,
-		 struct pnfs_layout_range *range)
+static bool
+pnfs_lseg_range_match(const struct pnfs_layout_range *ls_range,
+		 const struct pnfs_layout_range *range)
 {
 	struct pnfs_layout_range range1;
 
 	if ((range->iomode == IOMODE_RW &&
 	     ls_range->iomode != IOMODE_RW) ||
-	    !lo_seg_intersecting(ls_range, range))
+	    !pnfs_lseg_range_intersecting(ls_range, range))
 		return 0;
 
 	/* range1 covers only the first byte in the range */
 	range1 = *range;
 	range1.length = 1;
-	return lo_seg_contained(ls_range, &range1);
+	return pnfs_lseg_range_contained(ls_range, &range1);
 }
 
 /*
@@ -1121,12 +1379,11 @@
 
 	list_for_each_entry(lseg, &lo->plh_segs, pls_list) {
 		if (test_bit(NFS_LSEG_VALID, &lseg->pls_flags) &&
-		    is_matching_lseg(&lseg->pls_range, range)) {
+		    !test_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags) &&
+		    pnfs_lseg_range_match(&lseg->pls_range, range)) {
 			ret = pnfs_get_lseg(lseg);
 			break;
 		}
-		if (lseg->pls_range.offset > range->offset)
-			break;
 	}
 
 	dprintk("%s:Return lseg %p ref %d\n",
@@ -1209,6 +1466,37 @@
 	return ret;
 }
 
+/* stop waiting if someone clears NFS_LAYOUT_RETRY_LAYOUTGET bit. */
+static int pnfs_layoutget_retry_bit_wait(struct wait_bit_key *key, int mode)
+{
+	if (!test_bit(NFS_LAYOUT_RETRY_LAYOUTGET, key->flags))
+		return 1;
+	return nfs_wait_bit_killable(key, mode);
+}
+
+static bool pnfs_prepare_to_retry_layoutget(struct pnfs_layout_hdr *lo)
+{
+	if (!pnfs_should_retry_layoutget(lo))
+		return false;
+	/*
+	 * 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,
+				   pnfs_layoutget_retry_bit_wait,
+				   TASK_UNINTERRUPTIBLE);
+}
+
+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);
+}
+
 /*
  * Layout segment is retreived from the server if not cached.
  * The appropriate layout segment is referenced and returned to the caller.
@@ -1236,9 +1524,15 @@
 	if (!pnfs_enabled_sb(NFS_SERVER(ino)))
 		goto out;
 
+	if (iomode == IOMODE_READ && i_size_read(ino) == 0)
+		goto out;
+
 	if (pnfs_within_mdsthreshold(ctx, ino, iomode))
 		goto out;
 
+lookup_again:
+	nfs4_client_recover_expired_lease(clp);
+	first = false;
 	spin_lock(&ino->i_lock);
 	lo = pnfs_find_alloc_layout(ino, ctx, gfp_flags);
 	if (lo == NULL) {
@@ -1253,27 +1547,61 @@
 	}
 
 	/* if LAYOUTGET already failed once we don't try again */
-	if (pnfs_layout_io_test_failed(lo, iomode))
+	if (pnfs_layout_io_test_failed(lo, iomode) &&
+	    !pnfs_should_retry_layoutget(lo))
 		goto out_unlock;
 
-	/* Check to see if the layout for the given range already exists */
-	lseg = pnfs_find_lseg(lo, &arg);
-	if (lseg)
-		goto out_unlock;
+	first = list_empty(&lo->plh_segs);
+	if (first) {
+		/* 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);
+			wait_on_bit(&lo->plh_flags, NFS_LAYOUT_FIRST_LAYOUTGET,
+				    TASK_UNINTERRUPTIBLE);
+			pnfs_put_layout_hdr(lo);
+			goto lookup_again;
+		}
+	} else {
+		/* Check to see if the layout for the given range
+		 * already exists
+		 */
+		lseg = pnfs_find_lseg(lo, &arg);
+		if (lseg)
+			goto out_unlock;
+	}
+
+	/*
+	 * 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__);
+		if (pnfs_prepare_to_retry_layoutget(lo)) {
+			if (first)
+				pnfs_clear_first_layoutget(lo);
+			pnfs_put_layout_hdr(lo);
+			dprintk("%s retrying\n", __func__);
+			goto lookup_again;
+		}
+		goto out_put_layout_hdr;
+	}
 
-	if (pnfs_layoutgets_blocked(lo, 0))
+	if (pnfs_layoutgets_blocked(lo))
 		goto out_unlock;
 	atomic_inc(&lo->plh_outstanding);
-
-	first = list_empty(&lo->plh_layouts) ? true : false;
 	spin_unlock(&ino->i_lock);
 
-	if (first) {
+	if (list_empty(&lo->plh_layouts)) {
 		/* 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);
-		list_add_tail(&lo->plh_layouts, &server->layouts);
+		if (list_empty(&lo->plh_layouts))
+			list_add_tail(&lo->plh_layouts, &server->layouts);
 		spin_unlock(&clp->cl_lock);
 	}
 
@@ -1286,8 +1614,11 @@
 		arg.length = PAGE_CACHE_ALIGN(arg.length);
 
 	lseg = send_layoutget(lo, ctx, &arg, gfp_flags);
+	pnfs_clear_retry_layoutget(lo);
 	atomic_dec(&lo->plh_outstanding);
 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 "
@@ -1305,6 +1636,26 @@
 }
 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;
+}
+
 struct pnfs_layout_segment *
 pnfs_layout_process(struct nfs4_layoutget *lgp)
 {
@@ -1312,7 +1663,11 @@
 	struct nfs4_layoutget_res *res = &lgp->res;
 	struct pnfs_layout_segment *lseg;
 	struct inode *ino = lo->plh_inode;
-	int status = 0;
+	LIST_HEAD(free_me);
+	int status = -EINVAL;
+
+	if (!pnfs_sanity_check_layout_range(&res->range))
+		goto out;
 
 	/* Inject layout blob into I/O device driver */
 	lseg = NFS_SERVER(ino)->pnfs_curr_ld->alloc_lseg(lo, res, lgp->gfp_flags);
@@ -1326,32 +1681,45 @@
 		goto out;
 	}
 
+	init_lseg(lo, lseg);
+	lseg->pls_range = res->range;
+
 	spin_lock(&ino->i_lock);
-	if (test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
-		dprintk("%s forget reply due to recall\n", __func__);
+	if (pnfs_layoutgets_blocked(lo)) {
+		dprintk("%s forget reply due to state\n", __func__);
 		goto out_forget_reply;
 	}
 
-	if (pnfs_layoutgets_blocked(lo, 1) ||
-	    pnfs_layout_stateid_blocked(lo, &res->stateid)) {
-		dprintk("%s forget reply due to state\n", __func__);
-		goto out_forget_reply;
+	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__);
+			status = -EAGAIN;
+			goto out_forget_reply;
+		}
+		pnfs_set_layout_stateid(lo, &res->stateid, false);
+	} else {
+		/*
+		 * We got an entirely new state ID.  Mark all segments for the
+		 * inode invalid, and don't bother validating the stateid
+		 * sequence number.
+		 */
+		pnfs_mark_matching_lsegs_invalid(lo, &free_me, NULL);
+
+		nfs4_stateid_copy(&lo->plh_stateid, &res->stateid);
+		lo->plh_barrier = be32_to_cpu(res->stateid.seqid);
 	}
 
-	/* Done processing layoutget. Set the layout stateid */
-	pnfs_set_layout_stateid(lo, &res->stateid, false);
+	clear_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags);
 
-	init_lseg(lo, lseg);
-	lseg->pls_range = res->range;
 	pnfs_get_lseg(lseg);
-	pnfs_layout_insert_lseg(lo, lseg);
+	pnfs_layout_insert_lseg(lo, lseg, &free_me);
 
-	if (res->return_on_close) {
+	if (res->return_on_close)
 		set_bit(NFS_LSEG_ROC, &lseg->pls_flags);
-		set_bit(NFS_LAYOUT_ROC, &lo->plh_flags);
-	}
 
 	spin_unlock(&ino->i_lock);
+	pnfs_free_lseg_list(&free_me);
 	return lseg;
 out:
 	return ERR_PTR(status);
@@ -1363,29 +1731,80 @@
 	goto out;
 }
 
+static void
+pnfs_mark_matching_lsegs_return(struct pnfs_layout_hdr *lo,
+				struct list_head *tmp_list,
+				struct pnfs_layout_range *return_range)
+{
+	struct pnfs_layout_segment *lseg, *next;
+
+	dprintk("%s:Begin lo %p\n", __func__, lo);
+
+	if (list_empty(&lo->plh_segs))
+		return;
+
+	list_for_each_entry_safe(lseg, next, &lo->plh_segs, pls_list)
+		if (should_free_lseg(&lseg->pls_range, return_range)) {
+			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);
+			set_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags);
+			mark_lseg_invalid(lseg, tmp_list);
+			set_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE,
+					&lo->plh_flags);
+		}
+}
+
+void pnfs_error_mark_layout_for_return(struct inode *inode,
+				       struct pnfs_layout_segment *lseg)
+{
+	struct pnfs_layout_hdr *lo = NFS_I(inode)->layout;
+	int iomode = pnfs_iomode_to_fail_bit(lseg->pls_range.iomode);
+	struct pnfs_layout_range range = {
+		.iomode = lseg->pls_range.iomode,
+		.offset = 0,
+		.length = NFS4_MAX_UINT64,
+	};
+	LIST_HEAD(free_me);
+
+	spin_lock(&inode->i_lock);
+	/* set failure bit so that pnfs path will be retried later */
+	pnfs_layout_set_fail_bit(lo, iomode);
+	if (lo->plh_return_iomode == 0)
+		lo->plh_return_iomode = range.iomode;
+	else if (lo->plh_return_iomode != range.iomode)
+		lo->plh_return_iomode = IOMODE_ANY;
+	/*
+	 * 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.
+	 */
+	pnfs_mark_matching_lsegs_return(lo, &free_me, &range);
+	spin_unlock(&inode->i_lock);
+	pnfs_free_lseg_list(&free_me);
+}
+EXPORT_SYMBOL_GPL(pnfs_error_mark_layout_for_return);
+
 void
 pnfs_generic_pg_init_read(struct nfs_pageio_descriptor *pgio, struct nfs_page *req)
 {
 	u64 rd_size = req->wb_bytes;
 
-	WARN_ON_ONCE(pgio->pg_lseg != NULL);
+	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);
 
-	if (req->wb_offset != req->wb_pgbase) {
-		nfs_pageio_reset_read_mds(pgio);
-		return;
+		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
+						   req->wb_context,
+						   req_offset(req),
+						   rd_size,
+						   IOMODE_READ,
+						   GFP_KERNEL);
 	}
-
-	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,
-					   GFP_KERNEL);
 	/* If no lseg, fall back to read through mds */
 	if (pgio->pg_lseg == NULL)
 		nfs_pageio_reset_read_mds(pgio);
@@ -1397,19 +1816,13 @@
 pnfs_generic_pg_init_write(struct nfs_pageio_descriptor *pgio,
 			   struct nfs_page *req, u64 wb_size)
 {
-	WARN_ON_ONCE(pgio->pg_lseg != NULL);
-
-	if (req->wb_offset != req->wb_pgbase) {
-		nfs_pageio_reset_write_mds(pgio);
-		return;
-	}
-
-	pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
-					   req->wb_context,
-					   req_offset(req),
-					   wb_size,
-					   IOMODE_RW,
-					   GFP_NOFS);
+	if (pgio->pg_lseg == NULL)
+		pgio->pg_lseg = pnfs_update_layout(pgio->pg_inode,
+						   req->wb_context,
+						   req_offset(req),
+						   wb_size,
+						   IOMODE_RW,
+						   GFP_NOFS);
 	/* If no lseg, fall back to write through mds */
 	if (pgio->pg_lseg == NULL)
 		nfs_pageio_reset_write_mds(pgio);
@@ -1417,93 +1830,81 @@
 EXPORT_SYMBOL_GPL(pnfs_generic_pg_init_write);
 
 void
-pnfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *inode,
-		      const struct nfs_pgio_completion_ops *compl_ops)
+pnfs_generic_pg_cleanup(struct nfs_pageio_descriptor *desc)
 {
-	struct nfs_server *server = NFS_SERVER(inode);
-	struct pnfs_layoutdriver_type *ld = server->pnfs_curr_ld;
-
-	if (ld == NULL)
-		nfs_pageio_init_read(pgio, inode, compl_ops);
-	else
-		nfs_pageio_init(pgio, inode, ld->pg_read_ops, compl_ops, server->rsize, 0);
+	if (desc->pg_lseg) {
+		pnfs_put_lseg(desc->pg_lseg);
+		desc->pg_lseg = NULL;
+	}
 }
+EXPORT_SYMBOL_GPL(pnfs_generic_pg_cleanup);
 
-void
-pnfs_pageio_init_write(struct nfs_pageio_descriptor *pgio, struct inode *inode,
-		       int ioflags,
-		       const struct nfs_pgio_completion_ops *compl_ops)
+/*
+ * 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)
 {
-	struct nfs_server *server = NFS_SERVER(inode);
-	struct pnfs_layoutdriver_type *ld = server->pnfs_curr_ld;
-
-	if (ld == NULL)
-		nfs_pageio_init_write(pgio, inode, ioflags, compl_ops);
-	else
-		nfs_pageio_init(pgio, inode, ld->pg_write_ops, compl_ops, server->wsize, ioflags);
-}
+	unsigned int size;
+	u64 seg_end, req_start, seg_left;
 
-bool
-pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
-		     struct nfs_page *req)
-{
-	if (pgio->pg_lseg == NULL)
-		return nfs_generic_pg_test(pgio, prev, req);
+	size = nfs_generic_pg_test(pgio, prev, req);
+	if (!size)
+		return 0;
 
 	/*
-	 * Test if a nfs_page is fully contained in the pnfs_layout_range.
-	 * Note that this test makes several assumptions:
-	 * - that the previous nfs_page in the struct nfs_pageio_descriptor
-	 *   is known to lie within the range.
-	 *   - that the nfs_page being tested is known to be contiguous with the
-	 *   previous nfs_page.
-	 *   - Layout ranges are page aligned, so we only have to test the
-	 *   start offset of the request.
+	 * '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?
 	 *
 	 */
-	return req_offset(req) < end_offset(pgio->pg_lseg->pls_range.offset,
-					 pgio->pg_lseg->pls_range.length);
+	if (pgio->pg_lseg) {
+		seg_end = end_offset(pgio->pg_lseg->pls_range.offset,
+				     pgio->pg_lseg->pls_range.length);
+		req_start = req_offset(req);
+		WARN_ON_ONCE(req_start >= seg_end);
+		/* start of request is past the last byte of this segment */
+		if (req_start >= seg_end) {
+			/* reference the new lseg */
+			if (pgio->pg_ops->pg_cleanup)
+				pgio->pg_ops->pg_cleanup(pgio);
+			if (pgio->pg_ops->pg_init)
+				pgio->pg_ops->pg_init(pgio, req);
+			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 inode *inode,
-				struct list_head *head,
-				const struct nfs_pgio_completion_ops *compl_ops,
-				struct nfs_direct_req *dreq)
+int pnfs_write_done_resend_to_mds(struct nfs_pgio_header *hdr)
 {
 	struct nfs_pageio_descriptor pgio;
-	LIST_HEAD(failed);
 
 	/* Resend all requests through the MDS */
-	nfs_pageio_init_write(&pgio, inode, FLUSH_STABLE, compl_ops);
-	pgio.pg_dreq = dreq;
-	while (!list_empty(head)) {
-		struct nfs_page *req = nfs_list_entry(head->next);
-
-		nfs_list_remove_request(req);
-		if (!nfs_pageio_add_request(&pgio, req))
-			nfs_list_add_request(req, &failed);
-	}
-	nfs_pageio_complete(&pgio);
-
-	if (!list_empty(&failed)) {
-		/* For some reason our attempt to resend pages. Mark the
-		 * overall send request as having failed, and let
-		 * nfs_writeback_release_full deal with the error.
-		 */
-		list_move(&failed, head);
-		return -EIO;
-	}
-	return 0;
+	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_write_data *data)
+static void pnfs_ld_handle_write_error(struct nfs_pgio_header *hdr)
 {
-	struct nfs_pgio_header *hdr = data->header;
 
 	dprintk("pnfs write error = %d\n", hdr->pnfs_error);
 	if (NFS_SERVER(hdr->inode)->pnfs_curr_ld->flags &
@@ -1511,49 +1912,47 @@
 		pnfs_return_layout(hdr->inode);
 	}
 	if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags))
-		data->task.tk_status = pnfs_write_done_resend_to_mds(hdr->inode,
-							&hdr->pages,
-							hdr->completion_ops,
-							hdr->dreq);
+		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_write_data *data)
+void pnfs_ld_write_done(struct nfs_pgio_header *hdr)
 {
-	struct nfs_pgio_header *hdr = data->header;
-
-	if (!hdr->pnfs_error) {
-		pnfs_set_layoutcommit(data);
-		hdr->mds_ops->rpc_call_done(&data->task, data);
-	} else
-		pnfs_ld_handle_write_error(data);
-	hdr->mds_ops->rpc_release(data);
+	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_write_data *data)
+		struct nfs_pgio_header *hdr)
 {
-	struct nfs_pgio_header *hdr = data->header;
+	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, &desc->pg_list);
+		list_splice_tail_init(&hdr->pages, &mirror->pg_list);
 		nfs_pageio_reset_write_mds(desc);
-		desc->pg_recoalesce = 1;
+		mirror->pg_recoalesce = 1;
 	}
-	nfs_writedata_release(data);
+	nfs_pgio_data_destroy(hdr);
+	hdr->release(hdr);
 }
 
 static enum pnfs_try_status
-pnfs_try_to_write_data(struct nfs_write_data *wdata,
+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 nfs_pgio_header *hdr = wdata->header;
 	struct inode *inode = hdr->inode;
 	enum pnfs_try_status trypnfs;
 	struct nfs_server *nfss = NFS_SERVER(inode);
@@ -1561,8 +1960,8 @@
 	hdr->mds_ops = call_ops;
 
 	dprintk("%s: Writing ino:%lu %u@%llu (how %d)\n", __func__,
-		inode->i_ino, wdata->args.count, wdata->args.offset, how);
-	trypnfs = nfss->pnfs_curr_ld->write_pagelist(wdata, how);
+		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);
@@ -1570,146 +1969,108 @@
 }
 
 static void
-pnfs_do_multiple_writes(struct nfs_pageio_descriptor *desc, struct list_head *head, int how)
+pnfs_do_write(struct nfs_pageio_descriptor *desc,
+	      struct nfs_pgio_header *hdr, int how)
 {
-	struct nfs_write_data *data;
 	const struct rpc_call_ops *call_ops = desc->pg_rpc_callops;
 	struct pnfs_layout_segment *lseg = desc->pg_lseg;
+	enum pnfs_try_status trypnfs;
 
-	desc->pg_lseg = NULL;
-	while (!list_empty(head)) {
-		enum pnfs_try_status trypnfs;
-
-		data = list_first_entry(head, struct nfs_write_data, list);
-		list_del_init(&data->list);
-
-		trypnfs = pnfs_try_to_write_data(data, call_ops, lseg, how);
-		if (trypnfs == PNFS_NOT_ATTEMPTED)
-			pnfs_write_through_mds(desc, data);
-	}
-	pnfs_put_lseg(lseg);
+	trypnfs = pnfs_try_to_write_data(hdr, call_ops, lseg, how);
+	if (trypnfs == PNFS_NOT_ATTEMPTED)
+		pnfs_write_through_mds(desc, hdr);
 }
 
 static void pnfs_writehdr_free(struct nfs_pgio_header *hdr)
 {
 	pnfs_put_lseg(hdr->lseg);
-	nfs_writehdr_free(hdr);
+	nfs_pgio_header_free(hdr);
 }
-EXPORT_SYMBOL_GPL(pnfs_writehdr_free);
 
 int
 pnfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
 {
-	struct nfs_write_header *whdr;
+	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
+
 	struct nfs_pgio_header *hdr;
 	int ret;
 
-	whdr = nfs_writehdr_alloc();
-	if (!whdr) {
-		desc->pg_completion_ops->error_cleanup(&desc->pg_list);
-		pnfs_put_lseg(desc->pg_lseg);
-		desc->pg_lseg = NULL;
+	hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
+	if (!hdr) {
+		desc->pg_completion_ops->error_cleanup(&mirror->pg_list);
 		return -ENOMEM;
 	}
-	hdr = &whdr->header;
 	nfs_pgheader_init(desc, hdr, pnfs_writehdr_free);
+
 	hdr->lseg = pnfs_get_lseg(desc->pg_lseg);
-	atomic_inc(&hdr->refcnt);
-	ret = nfs_generic_flush(desc, hdr);
-	if (ret != 0) {
-		pnfs_put_lseg(desc->pg_lseg);
-		desc->pg_lseg = NULL;
-	} else
-		pnfs_do_multiple_writes(desc, &hdr->rpc_list, desc->pg_ioflags);
-	if (atomic_dec_and_test(&hdr->refcnt))
-		hdr->completion_ops->completion(hdr);
+	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 inode *inode,
-				struct list_head *head,
-				const struct nfs_pgio_completion_ops *compl_ops,
-				struct nfs_direct_req *dreq)
+int pnfs_read_done_resend_to_mds(struct nfs_pgio_header *hdr)
 {
 	struct nfs_pageio_descriptor pgio;
-	LIST_HEAD(failed);
 
 	/* Resend all requests through the MDS */
-	nfs_pageio_init_read(&pgio, inode, compl_ops);
-	pgio.pg_dreq = dreq;
-	while (!list_empty(head)) {
-		struct nfs_page *req = nfs_list_entry(head->next);
-
-		nfs_list_remove_request(req);
-		if (!nfs_pageio_add_request(&pgio, req))
-			nfs_list_add_request(req, &failed);
-	}
-	nfs_pageio_complete(&pgio);
-
-	if (!list_empty(&failed)) {
-		list_move(&failed, head);
-		return -EIO;
-	}
-	return 0;
+	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_read_data *data)
+static void pnfs_ld_handle_read_error(struct nfs_pgio_header *hdr)
 {
-	struct nfs_pgio_header *hdr = data->header;
-
 	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))
-		data->task.tk_status = pnfs_read_done_resend_to_mds(hdr->inode,
-							&hdr->pages,
-							hdr->completion_ops,
-							hdr->dreq);
+		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_read_data *data)
+void pnfs_ld_read_done(struct nfs_pgio_header *hdr)
 {
-	struct nfs_pgio_header *hdr = data->header;
-
 	if (likely(!hdr->pnfs_error)) {
-		__nfs4_read_done_cb(data);
-		hdr->mds_ops->rpc_call_done(&data->task, data);
-	} else
-		pnfs_ld_handle_read_error(data);
-	hdr->mds_ops->rpc_release(data);
+		__nfs4_read_done_cb(hdr);
+		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_read_data *data)
+		struct nfs_pgio_header *hdr)
 {
-	struct nfs_pgio_header *hdr = data->header;
+	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, &desc->pg_list);
+		list_splice_tail_init(&hdr->pages, &mirror->pg_list);
 		nfs_pageio_reset_read_mds(desc);
-		desc->pg_recoalesce = 1;
+		mirror->pg_recoalesce = 1;
 	}
-	nfs_readdata_release(data);
+	nfs_pgio_data_destroy(hdr);
+	hdr->release(hdr);
 }
 
 /*
  * Call the appropriate parallel I/O subsystem read function.
  */
 static enum pnfs_try_status
-pnfs_try_to_read_data(struct nfs_read_data *rdata,
+pnfs_try_to_read_data(struct nfs_pgio_header *hdr,
 		       const struct rpc_call_ops *call_ops,
 		       struct pnfs_layout_segment *lseg)
 {
-	struct nfs_pgio_header *hdr = rdata->header;
 	struct inode *inode = hdr->inode;
 	struct nfs_server *nfss = NFS_SERVER(inode);
 	enum pnfs_try_status trypnfs;
@@ -1717,74 +2078,77 @@
 	hdr->mds_ops = call_ops;
 
 	dprintk("%s: Reading ino:%lu %u@%llu\n",
-		__func__, inode->i_ino, rdata->args.count, rdata->args.offset);
+		__func__, inode->i_ino, hdr->args.count, hdr->args.offset);
 
-	trypnfs = nfss->pnfs_curr_ld->read_pagelist(rdata);
+	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. */
+int pnfs_read_resend_pnfs(struct nfs_pgio_header *hdr)
+{
+	struct nfs_pageio_descriptor pgio;
+
+	nfs_pageio_init_read(&pgio, hdr->inode, false, hdr->completion_ops);
+	return nfs_pageio_resend(&pgio, hdr);
+}
+EXPORT_SYMBOL_GPL(pnfs_read_resend_pnfs);
+
 static void
-pnfs_do_multiple_reads(struct nfs_pageio_descriptor *desc, struct list_head *head)
+pnfs_do_read(struct nfs_pageio_descriptor *desc, struct nfs_pgio_header *hdr)
 {
-	struct nfs_read_data *data;
 	const struct rpc_call_ops *call_ops = desc->pg_rpc_callops;
 	struct pnfs_layout_segment *lseg = desc->pg_lseg;
+	enum pnfs_try_status trypnfs;
+	int err = 0;
 
-	desc->pg_lseg = NULL;
-	while (!list_empty(head)) {
-		enum pnfs_try_status trypnfs;
-
-		data = list_first_entry(head, struct nfs_read_data, list);
-		list_del_init(&data->list);
-
-		trypnfs = pnfs_try_to_read_data(data, call_ops, lseg);
-		if (trypnfs == PNFS_NOT_ATTEMPTED)
-			pnfs_read_through_mds(desc, data);
-	}
-	pnfs_put_lseg(lseg);
+	trypnfs = pnfs_try_to_read_data(hdr, call_ops, lseg);
+	if (trypnfs == PNFS_TRY_AGAIN)
+		err = pnfs_read_resend_pnfs(hdr);
+	if (trypnfs == PNFS_NOT_ATTEMPTED || err)
+		pnfs_read_through_mds(desc, hdr);
 }
 
 static void pnfs_readhdr_free(struct nfs_pgio_header *hdr)
 {
 	pnfs_put_lseg(hdr->lseg);
-	nfs_readhdr_free(hdr);
+	nfs_pgio_header_free(hdr);
 }
-EXPORT_SYMBOL_GPL(pnfs_readhdr_free);
 
 int
 pnfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc)
 {
-	struct nfs_read_header *rhdr;
+	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
+
 	struct nfs_pgio_header *hdr;
 	int ret;
 
-	rhdr = nfs_readhdr_alloc();
-	if (!rhdr) {
-		desc->pg_completion_ops->error_cleanup(&desc->pg_list);
-		ret = -ENOMEM;
-		pnfs_put_lseg(desc->pg_lseg);
-		desc->pg_lseg = NULL;
-		return ret;
+	hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
+	if (!hdr) {
+		desc->pg_completion_ops->error_cleanup(&mirror->pg_list);
+		return -ENOMEM;
 	}
-	hdr = &rhdr->header;
 	nfs_pgheader_init(desc, hdr, pnfs_readhdr_free);
 	hdr->lseg = pnfs_get_lseg(desc->pg_lseg);
-	atomic_inc(&hdr->refcnt);
-	ret = nfs_generic_pagein(desc, hdr);
-	if (ret != 0) {
-		pnfs_put_lseg(desc->pg_lseg);
-		desc->pg_lseg = NULL;
-	} else
-		pnfs_do_multiple_reads(desc, &hdr->rpc_list);
-	if (atomic_dec_and_test(&hdr->refcnt))
-		hdr->completion_ops->completion(hdr);
+	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.
  */
@@ -1802,7 +2166,6 @@
 static void pnfs_list_write_lseg_done(struct inode *inode, struct list_head *listp)
 {
 	struct pnfs_layout_segment *lseg, *tmp;
-	unsigned long *bitlock = &NFS_I(inode)->flags;
 
 	/* Matched by references in pnfs_set_layoutcommit */
 	list_for_each_entry_safe(lseg, tmp, listp, pls_lc_list) {
@@ -1810,9 +2173,7 @@
 		pnfs_put_lseg(lseg);
 	}
 
-	clear_bit_unlock(NFS_INO_LAYOUTCOMMITTING, bitlock);
-	smp_mb__after_clear_bit();
-	wake_up_bit(bitlock, NFS_INO_LAYOUTCOMMITTING);
+	pnfs_clear_layoutcommitting(inode);
 }
 
 void pnfs_set_lo_fail(struct pnfs_layout_segment *lseg)
@@ -1822,29 +2183,27 @@
 EXPORT_SYMBOL_GPL(pnfs_set_lo_fail);
 
 void
-pnfs_set_layoutcommit(struct nfs_write_data *wdata)
+pnfs_set_layoutcommit(struct inode *inode, struct pnfs_layout_segment *lseg,
+		loff_t end_pos)
 {
-	struct nfs_pgio_header *hdr = wdata->header;
-	struct inode *inode = hdr->inode;
 	struct nfs_inode *nfsi = NFS_I(inode);
-	loff_t end_pos = wdata->mds_offset + wdata->res.count;
 	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);
-	}
-	if (!test_and_set_bit(NFS_LSEG_LAYOUTCOMMIT, &hdr->lseg->pls_flags)) {
+	} 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(hdr->lseg);
+		pnfs_get_lseg(lseg);
 	}
-	if (end_pos > nfsi->layout->plh_lwb)
-		nfsi->layout->plh_lwb = end_pos;
 	spin_unlock(&inode->i_lock);
 	dprintk("%s: lseg %p end_pos %llu\n",
-		__func__, hdr->lseg, nfsi->layout->plh_lwb);
+		__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 */
@@ -1873,50 +2232,44 @@
 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 = 0;
+	int status;
 
-	dprintk("--> %s inode %lu\n", __func__, inode->i_ino);
-
-	if (!test_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags))
+	if (!pnfs_layoutcommit_outstanding(inode))
 		return 0;
 
-	/* Note kzalloc ensures data->res.seq_res.sr_slot == NULL */
-	data = kzalloc(sizeof(*data), GFP_NOFS);
-	if (!data) {
-		status = -ENOMEM;
-		goto out;
-	}
-
-	if (!test_bit(NFS_INO_LAYOUTCOMMIT, &nfsi->flags))
-		goto out_free;
+	dprintk("--> %s inode %lu\n", __func__, inode->i_ino);
 
+	status = -EAGAIN;
 	if (test_and_set_bit(NFS_INO_LAYOUTCOMMITTING, &nfsi->flags)) {
-		if (!sync) {
-			status = -EAGAIN;
-			goto out_free;
-		}
-		status = wait_on_bit_lock(&nfsi->flags, NFS_INO_LAYOUTCOMMITTING,
-					nfs_wait_bit_killable, TASK_KILLABLE);
+		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_free;
+			goto out;
 	}
 
-	INIT_LIST_HEAD(&data->lseg_list);
+	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)) {
-		clear_bit(NFS_INO_LAYOUTCOMMITTING, &nfsi->flags);
-		spin_unlock(&inode->i_lock);
-		wake_up_bit(&nfsi->flags, NFS_INO_LAYOUTCOMMITTING);
-		goto out_free;
-	}
+	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;
-	nfsi->layout->plh_lwb = 0;
 
 	nfs4_stateid_copy(&data->args.stateid, &nfsi->layout->plh_stateid);
 	spin_unlock(&inode->i_lock);
@@ -1929,16 +2282,40 @@
 	data->args.lastbytewritten = end_pos - 1;
 	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_free:
+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)
 {
@@ -1951,3 +2328,67 @@
 	}
 	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;
+	}
+	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;
+	nfs4_stateid_copy(&data->args.stateid, &hdr->plh_stateid);
+	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);
+	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);