pnfs: Prepare for flexfiles by pulling out common code

The flexfilelayout driver will share some common code
with the filelayout driver. This set of changes refactors
that common code out to avoid any module depenencies.
Signed-off-by: Tom Haynes <loghyr@primarydata.com>

fs/nfs/Makefile

@@ -27,7 +27,7 @@ nfsv4-y := nfs4proc.o nfs4xdr.o nfs4state.o nfs4renewd.o nfs4super.o nfs4file.o
 	  dns_resolve.o nfs4trace.o
 nfsv4-$(CONFIG_NFS_USE_LEGACY_DNS) += cache_lib.o
 nfsv4-$(CONFIG_SYSCTL)	+= nfs4sysctl.o
-nfsv4-$(CONFIG_NFS_V4_1)	+= pnfs.o pnfs_dev.o
+nfsv4-$(CONFIG_NFS_V4_1)	+= pnfs.o pnfs_dev.o pnfs_nfs.o
 nfsv4-$(CONFIG_NFS_V4_2)	+= nfs42proc.o
 
 obj-$(CONFIG_PNFS_FILE_LAYOUT) += filelayout/

fs/nfs/filelayout/filelayout.c

@@ -118,13 +118,6 @@ static void filelayout_reset_read(struct nfs_pgio_header *hdr)
 	}
 }
 
-static void filelayout_fenceme(struct inode *inode, struct pnfs_layout_hdr *lo)
-{
-	if (!test_and_clear_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
-		return;
-	pnfs_return_layout(inode);
-}
-
 static int filelayout_async_handle_error(struct rpc_task *task,
 					 struct nfs4_state *state,
 					 struct nfs_client *clp,
@@ -339,16 +332,6 @@ static void filelayout_read_count_stats(struct rpc_task *task, void *data)
 	rpc_count_iostats(task, NFS_SERVER(hdr->inode)->client->cl_metrics);
 }
 
-static void filelayout_read_release(void *data)
-{
-	struct nfs_pgio_header *hdr = data;
-	struct pnfs_layout_hdr *lo = hdr->lseg->pls_layout;
-
-	filelayout_fenceme(lo->plh_inode, lo);
-	nfs_put_client(hdr->ds_clp);
-	hdr->mds_ops->rpc_release(data);
-}
-
 static int filelayout_write_done_cb(struct rpc_task *task,
 				struct nfs_pgio_header *hdr)
 {
@@ -371,17 +354,6 @@ static int filelayout_write_done_cb(struct rpc_task *task,
 	return 0;
 }
 
-/* Fake up some data that will cause nfs_commit_release to retry the writes. */
-static void prepare_to_resend_writes(struct nfs_commit_data *data)
-{
-	struct nfs_page *first = nfs_list_entry(data->pages.next);
-
-	data->task.tk_status = 0;
-	memcpy(&data->verf.verifier, &first->wb_verf,
-	       sizeof(data->verf.verifier));
-	data->verf.verifier.data[0]++; /* ensure verifier mismatch */
-}
-
 static int filelayout_commit_done_cb(struct rpc_task *task,
 				     struct nfs_commit_data *data)
 {
@@ -393,7 +365,7 @@ static int filelayout_commit_done_cb(struct rpc_task *task,
 
 	switch (err) {
 	case -NFS4ERR_RESET_TO_MDS:
-		prepare_to_resend_writes(data);
+		pnfs_generic_prepare_to_resend_writes(data);
 		return -EAGAIN;
 	case -EAGAIN:
 		rpc_restart_call_prepare(task);
@@ -451,16 +423,6 @@ static void filelayout_write_count_stats(struct rpc_task *task, void *data)
 	rpc_count_iostats(task, NFS_SERVER(hdr->inode)->client->cl_metrics);
 }
 
-static void filelayout_write_release(void *data)
-{
-	struct nfs_pgio_header *hdr = data;
-	struct pnfs_layout_hdr *lo = hdr->lseg->pls_layout;
-
-	filelayout_fenceme(lo->plh_inode, lo);
-	nfs_put_client(hdr->ds_clp);
-	hdr->mds_ops->rpc_release(data);
-}
-
 static void filelayout_commit_prepare(struct rpc_task *task, void *data)
 {
 	struct nfs_commit_data *wdata = data;
@@ -471,14 +433,6 @@ static void filelayout_commit_prepare(struct rpc_task *task, void *data)
 			task);
 }
 
-static void filelayout_write_commit_done(struct rpc_task *task, void *data)
-{
-	struct nfs_commit_data *wdata = data;
-
-	/* Note this may cause RPC to be resent */
-	wdata->mds_ops->rpc_call_done(task, data);
-}
-
 static void filelayout_commit_count_stats(struct rpc_task *task, void *data)
 {
 	struct nfs_commit_data *cdata = data;
@@ -486,35 +440,25 @@ static void filelayout_commit_count_stats(struct rpc_task *task, void *data)
 	rpc_count_iostats(task, NFS_SERVER(cdata->inode)->client->cl_metrics);
 }
 
-static void filelayout_commit_release(void *calldata)
-{
-	struct nfs_commit_data *data = calldata;
-
-	data->completion_ops->completion(data);
-	pnfs_put_lseg(data->lseg);
-	nfs_put_client(data->ds_clp);
-	nfs_commitdata_release(data);
-}
-
 static const struct rpc_call_ops filelayout_read_call_ops = {
 	.rpc_call_prepare = filelayout_read_prepare,
 	.rpc_call_done = filelayout_read_call_done,
 	.rpc_count_stats = filelayout_read_count_stats,
-	.rpc_release = filelayout_read_release,
+	.rpc_release = pnfs_generic_rw_release,
 };
 
 static const struct rpc_call_ops filelayout_write_call_ops = {
 	.rpc_call_prepare = filelayout_write_prepare,
 	.rpc_call_done = filelayout_write_call_done,
 	.rpc_count_stats = filelayout_write_count_stats,
-	.rpc_release = filelayout_write_release,
+	.rpc_release = pnfs_generic_rw_release,
 };
 
 static const struct rpc_call_ops filelayout_commit_call_ops = {
 	.rpc_call_prepare = filelayout_commit_prepare,
-	.rpc_call_done = filelayout_write_commit_done,
+	.rpc_call_done = pnfs_generic_write_commit_done,
 	.rpc_count_stats = filelayout_commit_count_stats,
-	.rpc_release = filelayout_commit_release,
+	.rpc_release = pnfs_generic_commit_release,
 };
 
 static enum pnfs_try_status
@@ -1004,33 +948,6 @@ static u32 select_bucket_index(struct nfs4_filelayout_segment *fl, u32 j)
 		return j;
 }
 
-/* The generic layer is about to remove the req from the commit list.
- * If this will make the bucket empty, it will need to put the lseg reference.
- * Note this is must be called holding the inode (/cinfo) lock
- */
-static void
-filelayout_clear_request_commit(struct nfs_page *req,
-				struct nfs_commit_info *cinfo)
-{
-	struct pnfs_layout_segment *freeme = NULL;
-
-	if (!test_and_clear_bit(PG_COMMIT_TO_DS, &req->wb_flags))
-		goto out;
-	cinfo->ds->nwritten--;
-	if (list_is_singular(&req->wb_list)) {
-		struct pnfs_commit_bucket *bucket;
-
-		bucket = list_first_entry(&req->wb_list,
-					  struct pnfs_commit_bucket,
-					  written);
-		freeme = bucket->wlseg;
-		bucket->wlseg = NULL;
-	}
-out:
-	nfs_request_remove_commit_list(req, cinfo);
-	pnfs_put_lseg_locked(freeme);
-}
-
 static void
 filelayout_mark_request_commit(struct nfs_page *req,
 			       struct pnfs_layout_segment *lseg,
@@ -1064,7 +981,7 @@ filelayout_mark_request_commit(struct nfs_page *req,
 		 * is normally transferred to the COMMIT call and released
 		 * there.  It could also be released if the last req is pulled
 		 * off due to a rewrite, in which case it will be done in
-		 * filelayout_clear_request_commit
+		 * pnfs_generic_clear_request_commit
 		 */
 		buckets[i].wlseg = pnfs_get_lseg(lseg);
 	}
@@ -1142,97 +1059,11 @@ static int filelayout_initiate_commit(struct nfs_commit_data *data, int how)
 				   &filelayout_commit_call_ops, how,
 				   RPC_TASK_SOFTCONN);
 out_err:
-	prepare_to_resend_writes(data);
-	filelayout_commit_release(data);
+	pnfs_generic_prepare_to_resend_writes(data);
+	pnfs_generic_commit_release(data);
 	return -EAGAIN;
 }
 
-static int
-transfer_commit_list(struct list_head *src, struct list_head *dst,
-		     struct nfs_commit_info *cinfo, int max)
-{
-	struct nfs_page *req, *tmp;
-	int ret = 0;
-
-	list_for_each_entry_safe(req, tmp, src, wb_list) {
-		if (!nfs_lock_request(req))
-			continue;
-		kref_get(&req->wb_kref);
-		if (cond_resched_lock(cinfo->lock))
-			list_safe_reset_next(req, tmp, wb_list);
-		nfs_request_remove_commit_list(req, cinfo);
-		clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
-		nfs_list_add_request(req, dst);
-		ret++;
-		if ((ret == max) && !cinfo->dreq)
-			break;
-	}
-	return ret;
-}
-
-/* Note called with cinfo->lock held. */
-static int
-filelayout_scan_ds_commit_list(struct pnfs_commit_bucket *bucket,
-			       struct nfs_commit_info *cinfo,
-			       int max)
-{
-	struct list_head *src = &bucket->written;
-	struct list_head *dst = &bucket->committing;
-	int ret;
-
-	ret = transfer_commit_list(src, dst, cinfo, max);
-	if (ret) {
-		cinfo->ds->nwritten -= ret;
-		cinfo->ds->ncommitting += ret;
-		bucket->clseg = bucket->wlseg;
-		if (list_empty(src))
-			bucket->wlseg = NULL;
-		else
-			pnfs_get_lseg(bucket->clseg);
-	}
-	return ret;
-}
-
-/* Move reqs from written to committing lists, returning count of number moved.
- * Note called with cinfo->lock held.
- */
-static int filelayout_scan_commit_lists(struct nfs_commit_info *cinfo,
-					int max)
-{
-	int i, rv = 0, cnt;
-
-	for (i = 0; i < cinfo->ds->nbuckets && max != 0; i++) {
-		cnt = filelayout_scan_ds_commit_list(&cinfo->ds->buckets[i],
-						     cinfo, max);
-		max -= cnt;
-		rv += cnt;
-	}
-	return rv;
-}
-
-/* Pull everything off the committing lists and dump into @dst */
-static void filelayout_recover_commit_reqs(struct list_head *dst,
-					   struct nfs_commit_info *cinfo)
-{
-	struct pnfs_commit_bucket *b;
-	struct pnfs_layout_segment *freeme;
-	int i;
-
-restart:
-	spin_lock(cinfo->lock);
-	for (i = 0, b = cinfo->ds->buckets; i < cinfo->ds->nbuckets; i++, b++) {
-		if (transfer_commit_list(&b->written, dst, cinfo, 0)) {
-			freeme = b->wlseg;
-			b->wlseg = NULL;
-			spin_unlock(cinfo->lock);
-			pnfs_put_lseg(freeme);
-			goto restart;
-		}
-	}
-	cinfo->ds->nwritten = 0;
-	spin_unlock(cinfo->lock);
-}
-
 /* filelayout_search_commit_reqs - Search lists in @cinfo for the head reqest
  *				   for @page
  * @cinfo - commit info for current inode
@@ -1263,108 +1094,14 @@ filelayout_search_commit_reqs(struct nfs_commit_info *cinfo, struct page *page)
 	return NULL;
 }
 
-static void filelayout_retry_commit(struct nfs_commit_info *cinfo, int idx)
-{
-	struct pnfs_ds_commit_info *fl_cinfo = cinfo->ds;
-	struct pnfs_commit_bucket *bucket;
-	struct pnfs_layout_segment *freeme;
-	int i;
-
-	for (i = idx; i < fl_cinfo->nbuckets; i++) {
-		bucket = &fl_cinfo->buckets[i];
-		if (list_empty(&bucket->committing))
-			continue;
-		nfs_retry_commit(&bucket->committing, bucket->clseg, cinfo);
-		spin_lock(cinfo->lock);
-		freeme = bucket->clseg;
-		bucket->clseg = NULL;
-		spin_unlock(cinfo->lock);
-		pnfs_put_lseg(freeme);
-	}
-}
-
-static unsigned int
-alloc_ds_commits(struct nfs_commit_info *cinfo, struct list_head *list)
-{
-	struct pnfs_ds_commit_info *fl_cinfo;
-	struct pnfs_commit_bucket *bucket;
-	struct nfs_commit_data *data;
-	int i;
-	unsigned int nreq = 0;
-
-	fl_cinfo = cinfo->ds;
-	bucket = fl_cinfo->buckets;
-	for (i = 0; i < fl_cinfo->nbuckets; i++, bucket++) {
-		if (list_empty(&bucket->committing))
-			continue;
-		data = nfs_commitdata_alloc();
-		if (!data)
-			break;
-		data->ds_commit_index = i;
-		spin_lock(cinfo->lock);
-		data->lseg = bucket->clseg;
-		bucket->clseg = NULL;
-		spin_unlock(cinfo->lock);
-		list_add(&data->pages, list);
-		nreq++;
-	}
-
-	/* Clean up on error */
-	filelayout_retry_commit(cinfo, i);
-	/* Caller will clean up entries put on list */
-	return nreq;
-}
-
-/* This follows nfs_commit_list pretty closely */
 static int
 filelayout_commit_pagelist(struct inode *inode, struct list_head *mds_pages,
 			   int how, struct nfs_commit_info *cinfo)
 {
-	struct nfs_commit_data *data, *tmp;
-	LIST_HEAD(list);
-	unsigned int nreq = 0;
-
-	if (!list_empty(mds_pages)) {
-		data = nfs_commitdata_alloc();
-		if (data != NULL) {
-			data->lseg = NULL;
-			list_add(&data->pages, &list);
-			nreq++;
-		} else {
-			nfs_retry_commit(mds_pages, NULL, cinfo);
-			filelayout_retry_commit(cinfo, 0);
-			cinfo->completion_ops->error_cleanup(NFS_I(inode));
-			return -ENOMEM;
-		}
-	}
-
-	nreq += alloc_ds_commits(cinfo, &list);
-
-	if (nreq == 0) {
-		cinfo->completion_ops->error_cleanup(NFS_I(inode));
-		goto out;
-	}
-
-	atomic_add(nreq, &cinfo->mds->rpcs_out);
-
-	list_for_each_entry_safe(data, tmp, &list, pages) {
-		list_del_init(&data->pages);
-		if (!data->lseg) {
-			nfs_init_commit(data, mds_pages, NULL, cinfo);
-			nfs_initiate_commit(NFS_CLIENT(inode), data,
-					    data->mds_ops, how, 0);
-		} else {
-			struct pnfs_commit_bucket *buckets;
-
-			buckets = cinfo->ds->buckets;
-			nfs_init_commit(data, &buckets[data->ds_commit_index].committing, data->lseg, cinfo);
-			filelayout_initiate_commit(data, how);
-		}
-	}
-out:
-	cinfo->ds->ncommitting = 0;
-	return PNFS_ATTEMPTED;
+	return pnfs_generic_commit_pagelist(inode, mds_pages, how, cinfo,
+					    filelayout_initiate_commit);
 }
+
 static struct nfs4_deviceid_node *
 filelayout_alloc_deviceid_node(struct nfs_server *server,
 		struct pnfs_device *pdev, gfp_t gfp_flags)
@@ -1421,9 +1158,9 @@ static struct pnfs_layoutdriver_type filelayout_type = {
 	.pg_write_ops		= &filelayout_pg_write_ops,
 	.get_ds_info		= &filelayout_get_ds_info,
 	.mark_request_commit	= filelayout_mark_request_commit,
-	.clear_request_commit	= filelayout_clear_request_commit,
-	.scan_commit_lists	= filelayout_scan_commit_lists,
-	.recover_commit_reqs	= filelayout_recover_commit_reqs,
+	.clear_request_commit	= pnfs_generic_clear_request_commit,
+	.scan_commit_lists	= pnfs_generic_scan_commit_lists,
+	.recover_commit_reqs	= pnfs_generic_recover_commit_reqs,
 	.search_commit_reqs	= filelayout_search_commit_reqs,
 	.commit_pagelist	= filelayout_commit_pagelist,
 	.read_pagelist		= filelayout_read_pagelist,

fs/nfs/filelayout/filelayout.h

@@ -119,17 +119,6 @@ FILELAYOUT_DEVID_NODE(struct pnfs_layout_segment *lseg)
 	return &FILELAYOUT_LSEG(lseg)->dsaddr->id_node;
 }
 
-static inline void
-filelayout_mark_devid_invalid(struct nfs4_deviceid_node *node)
-{
-	u32 *p = (u32 *)&node->deviceid;
-
-	printk(KERN_WARNING "NFS: Deviceid [%x%x%x%x] marked out of use.\n",
-		p[0], p[1], p[2], p[3]);
-
-	set_bit(NFS_DEVICEID_INVALID, &node->flags);
-}
-
 static inline bool
 filelayout_test_devid_invalid(struct nfs4_deviceid_node *node)
 {

fs/nfs/filelayout/filelayoutdev.c

@@ -708,7 +708,7 @@ nfs4_fl_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx)
 	if (ds == NULL) {
 		printk(KERN_ERR "NFS: %s: No data server for offset index %d\n",
 			__func__, ds_idx);
-		filelayout_mark_devid_invalid(devid);
+		pnfs_generic_mark_devid_invalid(devid);
 		goto out;
 	}
 	smp_rmb();

fs/nfs/pnfs.h

@@ -275,6 +275,23 @@ void nfs4_mark_deviceid_unavailable(struct nfs4_deviceid_node *node);
 bool nfs4_test_deviceid_unavailable(struct nfs4_deviceid_node *node);
 void nfs4_deviceid_purge_client(const struct nfs_client *);
 
+/* pnfs_nfs.c */
+void pnfs_generic_clear_request_commit(struct nfs_page *req,
+				       struct nfs_commit_info *cinfo);
+void pnfs_generic_commit_release(void *calldata);
+void pnfs_generic_prepare_to_resend_writes(struct nfs_commit_data *data);
+void pnfs_generic_rw_release(void *data);
+void pnfs_generic_recover_commit_reqs(struct list_head *dst,
+				      struct nfs_commit_info *cinfo);
+int pnfs_generic_commit_pagelist(struct inode *inode,
+				 struct list_head *mds_pages,
+				 int how,
+				 struct nfs_commit_info *cinfo,
+				 int (*initiate_commit)(struct nfs_commit_data *data,
+							int how));
+int pnfs_generic_scan_commit_lists(struct nfs_commit_info *cinfo, int max);
+void pnfs_generic_write_commit_done(struct rpc_task *task, void *data);
+
 static inline struct nfs4_deviceid_node *
 nfs4_get_deviceid(struct nfs4_deviceid_node *d)
 {
@@ -317,6 +334,12 @@ pnfs_get_ds_info(struct inode *inode)
 	return ld->get_ds_info(inode);
 }
 
+static inline void
+pnfs_generic_mark_devid_invalid(struct nfs4_deviceid_node *node)
+{
+	set_bit(NFS_DEVICEID_INVALID, &node->flags);
+}
+
 static inline bool
 pnfs_mark_request_commit(struct nfs_page *req, struct pnfs_layout_segment *lseg,
 			 struct nfs_commit_info *cinfo)

fs/nfs/pnfs_nfs.c

+/*
+ * Common NFS I/O  operations for the pnfs file based
+ * layout drivers.
+ *
+ * Copyright (c) 2014, Primary Data, Inc. All rights reserved.
+ *
+ * Tom Haynes <loghyr@primarydata.com>
+ */
+
+#include <linux/nfs_fs.h>
+#include <linux/nfs_page.h>
+
+#include "internal.h"
+#include "pnfs.h"
+
+static void pnfs_generic_fenceme(struct inode *inode,
+				 struct pnfs_layout_hdr *lo)
+{
+	if (!test_and_clear_bit(NFS_LAYOUT_RETURN, &lo->plh_flags))
+		return;
+	pnfs_return_layout(inode);
+}
+
+void pnfs_generic_rw_release(void *data)
+{
+	struct nfs_pgio_header *hdr = data;
+	struct pnfs_layout_hdr *lo = hdr->lseg->pls_layout;
+
+	pnfs_generic_fenceme(lo->plh_inode, lo);
+	nfs_put_client(hdr->ds_clp);
+	hdr->mds_ops->rpc_release(data);
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_rw_release);
+
+/* Fake up some data that will cause nfs_commit_release to retry the writes. */
+void pnfs_generic_prepare_to_resend_writes(struct nfs_commit_data *data)
+{
+	struct nfs_page *first = nfs_list_entry(data->pages.next);
+
+	data->task.tk_status = 0;
+	memcpy(&data->verf.verifier, &first->wb_verf,
+	       sizeof(data->verf.verifier));
+	data->verf.verifier.data[0]++; /* ensure verifier mismatch */
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_prepare_to_resend_writes);
+
+void pnfs_generic_write_commit_done(struct rpc_task *task, void *data)
+{
+	struct nfs_commit_data *wdata = data;
+
+	/* Note this may cause RPC to be resent */
+	wdata->mds_ops->rpc_call_done(task, data);
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_write_commit_done);
+
+void pnfs_generic_commit_release(void *calldata)
+{
+	struct nfs_commit_data *data = calldata;
+
+	data->completion_ops->completion(data);
+	pnfs_put_lseg(data->lseg);
+	nfs_put_client(data->ds_clp);
+	nfs_commitdata_release(data);
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_commit_release);
+
+/* The generic layer is about to remove the req from the commit list.
+ * If this will make the bucket empty, it will need to put the lseg reference.
+ * Note this is must be called holding the inode (/cinfo) lock
+ */
+void
+pnfs_generic_clear_request_commit(struct nfs_page *req,
+				  struct nfs_commit_info *cinfo)
+{
+	struct pnfs_layout_segment *freeme = NULL;
+
+	if (!test_and_clear_bit(PG_COMMIT_TO_DS, &req->wb_flags))
+		goto out;
+	cinfo->ds->nwritten--;
+	if (list_is_singular(&req->wb_list)) {
+		struct pnfs_commit_bucket *bucket;
+
+		bucket = list_first_entry(&req->wb_list,
+					  struct pnfs_commit_bucket,
+					  written);
+		freeme = bucket->wlseg;
+		bucket->wlseg = NULL;
+	}
+out:
+	nfs_request_remove_commit_list(req, cinfo);
+	pnfs_put_lseg_locked(freeme);
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_clear_request_commit);
+
+static int
+pnfs_generic_transfer_commit_list(struct list_head *src, struct list_head *dst,
+				  struct nfs_commit_info *cinfo, int max)
+{
+	struct nfs_page *req, *tmp;
+	int ret = 0;
+
+	list_for_each_entry_safe(req, tmp, src, wb_list) {
+		if (!nfs_lock_request(req))
+			continue;
+		kref_get(&req->wb_kref);
+		if (cond_resched_lock(cinfo->lock))
+			list_safe_reset_next(req, tmp, wb_list);
+		nfs_request_remove_commit_list(req, cinfo);
+		clear_bit(PG_COMMIT_TO_DS, &req->wb_flags);
+		nfs_list_add_request(req, dst);
+		ret++;
+		if ((ret == max) && !cinfo->dreq)
+			break;
+	}
+	return ret;
+}
+
+/* Note called with cinfo->lock held. */
+static int
+pnfs_generic_scan_ds_commit_list(struct pnfs_commit_bucket *bucket,
+				 struct nfs_commit_info *cinfo,
+				 int max)
+{
+	struct list_head *src = &bucket->written;
+	struct list_head *dst = &bucket->committing;
+	int ret;
+
+	ret = pnfs_generic_transfer_commit_list(src, dst, cinfo, max);
+	if (ret) {
+		cinfo->ds->nwritten -= ret;
+		cinfo->ds->ncommitting += ret;
+		bucket->clseg = bucket->wlseg;
+		if (list_empty(src))
+			bucket->wlseg = NULL;
+		else
+			pnfs_get_lseg(bucket->clseg);
+	}
+	return ret;
+}
+
+/* Move reqs from written to committing lists, returning count of number moved.
+ * Note called with cinfo->lock held.
+ */
+int pnfs_generic_scan_commit_lists(struct nfs_commit_info *cinfo,
+				   int max)
+{
+	int i, rv = 0, cnt;
+
+	for (i = 0; i < cinfo->ds->nbuckets && max != 0; i++) {
+		cnt = pnfs_generic_scan_ds_commit_list(&cinfo->ds->buckets[i],
+						       cinfo, max);
+		max -= cnt;
+		rv += cnt;
+	}
+	return rv;
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_scan_commit_lists);
+
+/* Pull everything off the committing lists and dump into @dst */
+void pnfs_generic_recover_commit_reqs(struct list_head *dst,
+				      struct nfs_commit_info *cinfo)
+{
+	struct pnfs_commit_bucket *b;
+	struct pnfs_layout_segment *freeme;
+	int i;
+
+restart:
+	spin_lock(cinfo->lock);
+	for (i = 0, b = cinfo->ds->buckets; i < cinfo->ds->nbuckets; i++, b++) {
+		if (pnfs_generic_transfer_commit_list(&b->written, dst,
+						      cinfo, 0)) {
+			freeme = b->wlseg;
+			b->wlseg = NULL;
+			spin_unlock(cinfo->lock);
+			pnfs_put_lseg(freeme);
+			goto restart;
+		}
+	}
+	cinfo->ds->nwritten = 0;
+	spin_unlock(cinfo->lock);
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_recover_commit_reqs);
+
+static void pnfs_generic_retry_commit(struct nfs_commit_info *cinfo, int idx)
+{
+	struct pnfs_ds_commit_info *fl_cinfo = cinfo->ds;
+	struct pnfs_commit_bucket *bucket;
+	struct pnfs_layout_segment *freeme;
+	int i;
+
+	for (i = idx; i < fl_cinfo->nbuckets; i++) {
+		bucket = &fl_cinfo->buckets[i];
+		if (list_empty(&bucket->committing))
+			continue;
+		nfs_retry_commit(&bucket->committing, bucket->clseg, cinfo);
+		spin_lock(cinfo->lock);
+		freeme = bucket->clseg;
+		bucket->clseg = NULL;
+		spin_unlock(cinfo->lock);
+		pnfs_put_lseg(freeme);
+	}
+}
+
+static unsigned int
+pnfs_generic_alloc_ds_commits(struct nfs_commit_info *cinfo,
+			      struct list_head *list)
+{
+	struct pnfs_ds_commit_info *fl_cinfo;
+	struct pnfs_commit_bucket *bucket;
+	struct nfs_commit_data *data;
+	int i;
+	unsigned int nreq = 0;
+
+	fl_cinfo = cinfo->ds;
+	bucket = fl_cinfo->buckets;
+	for (i = 0; i < fl_cinfo->nbuckets; i++, bucket++) {
+		if (list_empty(&bucket->committing))
+			continue;
+		data = nfs_commitdata_alloc();
+		if (!data)
+			break;
+		data->ds_commit_index = i;
+		spin_lock(cinfo->lock);
+		data->lseg = bucket->clseg;
+		bucket->clseg = NULL;
+		spin_unlock(cinfo->lock);
+		list_add(&data->pages, list);
+		nreq++;
+	}
+
+	/* Clean up on error */
+	pnfs_generic_retry_commit(cinfo, i);
+	return nreq;
+}
+
+/* This follows nfs_commit_list pretty closely */
+int
+pnfs_generic_commit_pagelist(struct inode *inode, struct list_head *mds_pages,
+			     int how, struct nfs_commit_info *cinfo,
+			     int (*initiate_commit)(struct nfs_commit_data *data,
+						    int how))
+{
+	struct nfs_commit_data *data, *tmp;
+	LIST_HEAD(list);
+	unsigned int nreq = 0;
+
+	if (!list_empty(mds_pages)) {
+		data = nfs_commitdata_alloc();
+		if (data != NULL) {
+			data->lseg = NULL;
+			list_add(&data->pages, &list);
+			nreq++;
+		} else {
+			nfs_retry_commit(mds_pages, NULL, cinfo);
+			pnfs_generic_retry_commit(cinfo, 0);
+			cinfo->completion_ops->error_cleanup(NFS_I(inode));
+			return -ENOMEM;
+		}
+	}
+
+	nreq += pnfs_generic_alloc_ds_commits(cinfo, &list);
+
+	if (nreq == 0) {
+		cinfo->completion_ops->error_cleanup(NFS_I(inode));
+		goto out;
+	}
+
+	atomic_add(nreq, &cinfo->mds->rpcs_out);
+
+	list_for_each_entry_safe(data, tmp, &list, pages) {
+		list_del_init(&data->pages);
+		if (!data->lseg) {
+			nfs_init_commit(data, mds_pages, NULL, cinfo);
+			nfs_initiate_commit(NFS_CLIENT(inode), data,
+					    data->mds_ops, how, 0);
+		} else {
+			struct pnfs_commit_bucket *buckets;
+
+			buckets = cinfo->ds->buckets;
+			nfs_init_commit(data,
+					&buckets[data->ds_commit_index].committing,
+					data->lseg,
+					cinfo);
+			initiate_commit(data, how);
+		}
+	}
+out:
+	cinfo->ds->ncommitting = 0;
+	return PNFS_ATTEMPTED;
+}
+EXPORT_SYMBOL_GPL(pnfs_generic_commit_pagelist);