1 files changed, 909 insertions, 212 deletions

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index d53857b148e..17fab89f635 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -9,29 +9,75 @@
  *
  */
 
-#include <linux/config.h>
 #include <linux/slab.h>
 #include <linux/file.h>
+#include <linux/sched.h>
 #include <linux/sunrpc/clnt.h>
+#include <linux/nfs.h>
 #include <linux/nfs3.h>
 #include <linux/nfs4.h>
 #include <linux/nfs_page.h>
 #include <linux/nfs_fs.h>
 #include <linux/nfs_mount.h>
+#include <linux/export.h>
 
-#define NFS_PARANOIA 1
+#include "internal.h"
+#include "pnfs.h"
 
-static kmem_cache_t *nfs_page_cachep;
+#define NFSDBG_FACILITY		NFSDBG_PAGECACHE
+
+static struct kmem_cache *nfs_page_cachep;
+static const struct rpc_call_ops nfs_pgio_common_ops;
+
+static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
+{
+	p->npages = pagecount;
+	if (pagecount <= ARRAY_SIZE(p->page_array))
+		p->pagevec = p->page_array;
+	else {
+		p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_KERNEL);
+		if (!p->pagevec)
+			p->npages = 0;
+	}
+	return p->pagevec != NULL;
+}
+
+void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
+		       struct nfs_pgio_header *hdr,
+		       void (*release)(struct nfs_pgio_header *hdr))
+{
+	hdr->req = nfs_list_entry(desc->pg_list.next);
+	hdr->inode = desc->pg_inode;
+	hdr->cred = hdr->req->wb_context->cred;
+	hdr->io_start = req_offset(hdr->req);
+	hdr->good_bytes = desc->pg_count;
+	hdr->dreq = desc->pg_dreq;
+	hdr->layout_private = desc->pg_layout_private;
+	hdr->release = release;
+	hdr->completion_ops = desc->pg_completion_ops;
+	if (hdr->completion_ops->init_hdr)
+		hdr->completion_ops->init_hdr(hdr);
+}
+EXPORT_SYMBOL_GPL(nfs_pgheader_init);
+
+void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
+{
+	spin_lock(&hdr->lock);
+	if (pos < hdr->io_start + hdr->good_bytes) {
+		set_bit(NFS_IOHDR_ERROR, &hdr->flags);
+		clear_bit(NFS_IOHDR_EOF, &hdr->flags);
+		hdr->good_bytes = pos - hdr->io_start;
+		hdr->error = error;
+	}
+	spin_unlock(&hdr->lock);
+}
 
 static inline struct nfs_page *
 nfs_page_alloc(void)
 {
-	struct nfs_page	*p;
-	p = kmem_cache_alloc(nfs_page_cachep, SLAB_KERNEL);
-	if (p) {
-		memset(p, 0, sizeof(*p));
+	struct nfs_page	*p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
+	if (p)
 		INIT_LIST_HEAD(&p->wb_list);
-	}
 	return p;
 }
 
@@ -41,56 +87,260 @@ nfs_page_free(struct nfs_page *p)
 	kmem_cache_free(nfs_page_cachep, p);
 }
 
+static void
+nfs_iocounter_inc(struct nfs_io_counter *c)
+{
+	atomic_inc(&c->io_count);
+}
+
+static void
+nfs_iocounter_dec(struct nfs_io_counter *c)
+{
+	if (atomic_dec_and_test(&c->io_count)) {
+		clear_bit(NFS_IO_INPROGRESS, &c->flags);
+		smp_mb__after_atomic();
+		wake_up_bit(&c->flags, NFS_IO_INPROGRESS);
+	}
+}
+
+static int
+__nfs_iocounter_wait(struct nfs_io_counter *c)
+{
+	wait_queue_head_t *wq = bit_waitqueue(&c->flags, NFS_IO_INPROGRESS);
+	DEFINE_WAIT_BIT(q, &c->flags, NFS_IO_INPROGRESS);
+	int ret = 0;
+
+	do {
+		prepare_to_wait(wq, &q.wait, TASK_KILLABLE);
+		set_bit(NFS_IO_INPROGRESS, &c->flags);
+		if (atomic_read(&c->io_count) == 0)
+			break;
+		ret = nfs_wait_bit_killable(&c->flags);
+	} while (atomic_read(&c->io_count) != 0);
+	finish_wait(wq, &q.wait);
+	return ret;
+}
+
+/**
+ * nfs_iocounter_wait - wait for i/o to complete
+ * @c: nfs_io_counter to use
+ *
+ * returns -ERESTARTSYS if interrupted by a fatal signal.
+ * Otherwise returns 0 once the io_count hits 0.
+ */
+int
+nfs_iocounter_wait(struct nfs_io_counter *c)
+{
+	if (atomic_read(&c->io_count) == 0)
+		return 0;
+	return __nfs_iocounter_wait(c);
+}
+
+static int nfs_wait_bit_uninterruptible(void *word)
+{
+	io_schedule();
+	return 0;
+}
+
+/*
+ * nfs_page_group_lock - lock the head of the page group
+ * @req - request in group that is to be locked
+ *
+ * this lock must be held if modifying the page group list
+ */
+void
+nfs_page_group_lock(struct nfs_page *req)
+{
+	struct nfs_page *head = req->wb_head;
+
+	WARN_ON_ONCE(head != head->wb_head);
+
+	wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
+			nfs_wait_bit_uninterruptible,
+			TASK_UNINTERRUPTIBLE);
+}
+
+/*
+ * nfs_page_group_unlock - unlock the head of the page group
+ * @req - request in group that is to be unlocked
+ */
+void
+nfs_page_group_unlock(struct nfs_page *req)
+{
+	struct nfs_page *head = req->wb_head;
+
+	WARN_ON_ONCE(head != head->wb_head);
+
+	smp_mb__before_atomic();
+	clear_bit(PG_HEADLOCK, &head->wb_flags);
+	smp_mb__after_atomic();
+	wake_up_bit(&head->wb_flags, PG_HEADLOCK);
+}
+
+/*
+ * nfs_page_group_sync_on_bit_locked
+ *
+ * must be called with page group lock held
+ */
+static bool
+nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
+{
+	struct nfs_page *head = req->wb_head;
+	struct nfs_page *tmp;
+
+	WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
+	WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
+
+	tmp = req->wb_this_page;
+	while (tmp != req) {
+		if (!test_bit(bit, &tmp->wb_flags))
+			return false;
+		tmp = tmp->wb_this_page;
+	}
+
+	/* true! reset all bits */
+	tmp = req;
+	do {
+		clear_bit(bit, &tmp->wb_flags);
+		tmp = tmp->wb_this_page;
+	} while (tmp != req);
+
+	return true;
+}
+
+/*
+ * nfs_page_group_sync_on_bit - set bit on current request, but only
+ *   return true if the bit is set for all requests in page group
+ * @req - request in page group
+ * @bit - PG_* bit that is used to sync page group
+ */
+bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
+{
+	bool ret;
+
+	nfs_page_group_lock(req);
+	ret = nfs_page_group_sync_on_bit_locked(req, bit);
+	nfs_page_group_unlock(req);
+
+	return ret;
+}
+
+/*
+ * nfs_page_group_init - Initialize the page group linkage for @req
+ * @req - a new nfs request
+ * @prev - the previous request in page group, or NULL if @req is the first
+ *         or only request in the group (the head).
+ */
+static inline void
+nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
+{
+	WARN_ON_ONCE(prev == req);
+
+	if (!prev) {
+		/* a head request */
+		req->wb_head = req;
+		req->wb_this_page = req;
+	} else {
+		/* a subrequest */
+		WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
+		WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
+		req->wb_head = prev->wb_head;
+		req->wb_this_page = prev->wb_this_page;
+		prev->wb_this_page = req;
+
+		/* All subrequests take a ref on the head request until
+		 * nfs_page_group_destroy is called */
+		kref_get(&req->wb_head->wb_kref);
+
+		/* grab extra ref if head request has extra ref from
+		 * the write/commit path to handle handoff between write
+		 * and commit lists */
+		if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
+			set_bit(PG_INODE_REF, &req->wb_flags);
+			kref_get(&req->wb_kref);
+		}
+	}
+}
+
+/*
+ * nfs_page_group_destroy - sync the destruction of page groups
+ * @req - request that no longer needs the page group
+ *
+ * releases the page group reference from each member once all
+ * members have called this function.
+ */
+static void
+nfs_page_group_destroy(struct kref *kref)
+{
+	struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
+	struct nfs_page *tmp, *next;
+
+	/* subrequests must release the ref on the head request */
+	if (req->wb_head != req)
+		nfs_release_request(req->wb_head);
+
+	if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
+		return;
+
+	tmp = req;
+	do {
+		next = tmp->wb_this_page;
+		/* unlink and free */
+		tmp->wb_this_page = tmp;
+		tmp->wb_head = tmp;
+		nfs_free_request(tmp);
+		tmp = next;
+	} while (tmp != req);
+}
+
 /**
  * nfs_create_request - Create an NFS read/write request.
- * @file: file descriptor to use
- * @inode: inode to which the request is attached
+ * @ctx: open context to use
  * @page: page to write
+ * @last: last nfs request created for this page group or NULL if head
  * @offset: starting offset within the page for the write
  * @count: number of bytes to read/write
  *
  * The page must be locked by the caller. This makes sure we never
- * create two different requests for the same page, and avoids
- * a possible deadlock when we reach the hard limit on the number
- * of dirty pages.
+ * create two different requests for the same page.
  * User should ensure it is safe to sleep in this function.
  */
 struct nfs_page *
-nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
-		   struct page *page,
-		   unsigned int offset, unsigned int count)
+nfs_create_request(struct nfs_open_context *ctx, struct page *page,
+		   struct nfs_page *last, unsigned int offset,
+		   unsigned int count)
 {
-	struct nfs_server *server = NFS_SERVER(inode);
 	struct nfs_page		*req;
+	struct nfs_lock_context *l_ctx;
 
-	/* Deal with hard limits.  */
-	for (;;) {
-		/* try to allocate the request struct */
-		req = nfs_page_alloc();
-		if (req != NULL)
-			break;
+	if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
+		return ERR_PTR(-EBADF);
+	/* try to allocate the request struct */
+	req = nfs_page_alloc();
+	if (req == NULL)
+		return ERR_PTR(-ENOMEM);
 
-		/* Try to free up at least one request in order to stay
-		 * below the hard limit
-		 */
-		if (signalled() && (server->flags & NFS_MOUNT_INTR))
-			return ERR_PTR(-ERESTARTSYS);
-		yield();
+	/* get lock context early so we can deal with alloc failures */
+	l_ctx = nfs_get_lock_context(ctx);
+	if (IS_ERR(l_ctx)) {
+		nfs_page_free(req);
+		return ERR_CAST(l_ctx);
 	}
+	req->wb_lock_context = l_ctx;
+	nfs_iocounter_inc(&l_ctx->io_count);
 
 	/* Initialize the request struct. Initially, we assume a
 	 * long write-back delay. This will be adjusted in
 	 * update_nfs_request below if the region is not locked. */
 	req->wb_page    = page;
-	atomic_set(&req->wb_complete, 0);
-	req->wb_index	= page->index;
+	req->wb_index	= page_file_index(page);
 	page_cache_get(page);
 	req->wb_offset  = offset;
 	req->wb_pgbase	= offset;
 	req->wb_bytes   = count;
-	atomic_set(&req->wb_count, 1);
 	req->wb_context = get_nfs_open_context(ctx);
-
+	kref_init(&req->wb_kref);
+	nfs_page_group_init(req, last);
 	return req;
 }
 
@@ -104,271 +354,709 @@ void nfs_unlock_request(struct nfs_page *req)
 		printk(KERN_ERR "NFS: Invalid unlock attempted\n");
 		BUG();
 	}
-	smp_mb__before_clear_bit();
+	smp_mb__before_atomic();
 	clear_bit(PG_BUSY, &req->wb_flags);
-	smp_mb__after_clear_bit();
+	smp_mb__after_atomic();
 	wake_up_bit(&req->wb_flags, PG_BUSY);
-	nfs_release_request(req);
 }
 
 /**
- * nfs_set_page_writeback_locked - Lock a request for writeback
+ * nfs_unlock_and_release_request - Unlock request and release the nfs_page
  * @req:
  */
-int nfs_set_page_writeback_locked(struct nfs_page *req)
+void nfs_unlock_and_release_request(struct nfs_page *req)
 {
-	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
-
-	if (!nfs_lock_request(req))
-		return 0;
-	radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
-	return 1;
-}
-
-/**
- * nfs_clear_page_writeback - Unlock request and wake up sleepers
- */
-void nfs_clear_page_writeback(struct nfs_page *req)
-{
-	struct nfs_inode *nfsi = NFS_I(req->wb_context->dentry->d_inode);
-
-	spin_lock(&nfsi->req_lock);
-	radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_WRITEBACK);
-	spin_unlock(&nfsi->req_lock);
 	nfs_unlock_request(req);
+	nfs_release_request(req);
 }
 
-/**
+/*
  * nfs_clear_request - Free up all resources allocated to the request
  * @req:
  *
- * Release page resources associated with a write request after it
- * has completed.
+ * Release page and open context resources associated with a read/write
+ * request after it has completed.
  */
-void nfs_clear_request(struct nfs_page *req)
+static void nfs_clear_request(struct nfs_page *req)
 {
-	if (req->wb_page) {
-		page_cache_release(req->wb_page);
+	struct page *page = req->wb_page;
+	struct nfs_open_context *ctx = req->wb_context;
+	struct nfs_lock_context *l_ctx = req->wb_lock_context;
+
+	if (page != NULL) {
+		page_cache_release(page);
 		req->wb_page = NULL;
 	}
+	if (l_ctx != NULL) {
+		nfs_iocounter_dec(&l_ctx->io_count);
+		nfs_put_lock_context(l_ctx);
+		req->wb_lock_context = NULL;
+	}
+	if (ctx != NULL) {
+		put_nfs_open_context(ctx);
+		req->wb_context = NULL;
+	}
 }
 
-
 /**
  * nfs_release_request - Release the count on an NFS read/write request
  * @req: request to release
  *
  * Note: Should never be called with the spinlock held!
  */
-void
-nfs_release_request(struct nfs_page *req)
+void nfs_free_request(struct nfs_page *req)
 {
-	if (!atomic_dec_and_test(&req->wb_count))
-		return;
+	WARN_ON_ONCE(req->wb_this_page != req);
 
-#ifdef NFS_PARANOIA
-	BUG_ON (!list_empty(&req->wb_list));
-	BUG_ON (NFS_WBACK_BUSY(req));
-#endif
+	/* extra debug: make sure no sync bits are still set */
+	WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
+	WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
+	WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
+	WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
+	WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 
-	/* Release struct file or cached credential */
+	/* Release struct file and open context */
 	nfs_clear_request(req);
-	put_nfs_open_context(req->wb_context);
 	nfs_page_free(req);
 }
 
-static int nfs_wait_bit_interruptible(void *word)
+void nfs_release_request(struct nfs_page *req)
 {
-	int ret = 0;
-
-	if (signal_pending(current))
-		ret = -ERESTARTSYS;
-	else
-		schedule();
-	return ret;
+	kref_put(&req->wb_kref, nfs_page_group_destroy);
 }
 
 /**
  * nfs_wait_on_request - Wait for a request to complete.
  * @req: request to wait upon.
  *
- * Interruptible by signals only if mounted with intr flag.
+ * Interruptible by fatal signals only.
  * The user is responsible for holding a count on the request.
  */
 int
 nfs_wait_on_request(struct nfs_page *req)
 {
-        struct rpc_clnt	*clnt = NFS_CLIENT(req->wb_context->dentry->d_inode);
-	sigset_t oldmask;
-	int ret = 0;
+	return wait_on_bit(&req->wb_flags, PG_BUSY,
+			nfs_wait_bit_uninterruptible,
+			TASK_UNINTERRUPTIBLE);
+}
+
+/*
+ * nfs_generic_pg_test - determine if requests can be coalesced
+ * @desc: pointer to descriptor
+ * @prev: previous request in desc, or NULL
+ * @req: this request
+ *
+ * Returns zero if @req can be coalesced into @desc, otherwise it returns
+ * the size of the request.
+ */
+size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
+			   struct nfs_page *prev, struct nfs_page *req)
+{
+	if (desc->pg_count > desc->pg_bsize) {
+		/* should never happen */
+		WARN_ON_ONCE(1);
+		return 0;
+	}
+
+	return min(desc->pg_bsize - desc->pg_count, (size_t)req->wb_bytes);
+}
+EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
+
+static inline struct nfs_rw_header *NFS_RW_HEADER(struct nfs_pgio_header *hdr)
+{
+	return container_of(hdr, struct nfs_rw_header, header);
+}
+
+/**
+ * nfs_rw_header_alloc - Allocate a header for a read or write
+ * @ops: Read or write function vector
+ */
+struct nfs_rw_header *nfs_rw_header_alloc(const struct nfs_rw_ops *ops)
+{
+	struct nfs_rw_header *header = ops->rw_alloc_header();
+
+	if (header) {
+		struct nfs_pgio_header *hdr = &header->header;
+
+		INIT_LIST_HEAD(&hdr->pages);
+		spin_lock_init(&hdr->lock);
+		atomic_set(&hdr->refcnt, 0);
+		hdr->rw_ops = ops;
+	}
+	return header;
+}
+EXPORT_SYMBOL_GPL(nfs_rw_header_alloc);
+
+/*
+ * nfs_rw_header_free - Free a read or write header
+ * @hdr: The header to free
+ */
+void nfs_rw_header_free(struct nfs_pgio_header *hdr)
+{
+	hdr->rw_ops->rw_free_header(NFS_RW_HEADER(hdr));
+}
+EXPORT_SYMBOL_GPL(nfs_rw_header_free);
+
+/**
+ * nfs_pgio_data_alloc - Allocate pageio data
+ * @hdr: The header making a request
+ * @pagecount: Number of pages to create
+ */
+static struct nfs_pgio_data *nfs_pgio_data_alloc(struct nfs_pgio_header *hdr,
+						 unsigned int pagecount)
+{
+	struct nfs_pgio_data *data, *prealloc;
 
-	if (!test_bit(PG_BUSY, &req->wb_flags))
+	prealloc = &NFS_RW_HEADER(hdr)->rpc_data;
+	if (prealloc->header == NULL)
+		data = prealloc;
+	else
+		data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
 		goto out;
-	/*
-	 * Note: the call to rpc_clnt_sigmask() suffices to ensure that we
-	 *	 are not interrupted if intr flag is not set
+
+	if (nfs_pgarray_set(&data->pages, pagecount)) {
+		data->header = hdr;
+		atomic_inc(&hdr->refcnt);
+	} else {
+		if (data != prealloc)
+			kfree(data);
+		data = NULL;
+	}
+out:
+	return data;
+}
+
+/**
+ * nfs_pgio_data_release - Properly free pageio data
+ * @data: The data to release
+ */
+void nfs_pgio_data_release(struct nfs_pgio_data *data)
+{
+	struct nfs_pgio_header *hdr = data->header;
+	struct nfs_rw_header *pageio_header = NFS_RW_HEADER(hdr);
+
+	put_nfs_open_context(data->args.context);
+	if (data->pages.pagevec != data->pages.page_array)
+		kfree(data->pages.pagevec);
+	if (data == &pageio_header->rpc_data) {
+		data->header = NULL;
+		data = NULL;
+	}
+	if (atomic_dec_and_test(&hdr->refcnt))
+		hdr->completion_ops->completion(hdr);
+	/* Note: we only free the rpc_task after callbacks are done.
+	 * See the comment in rpc_free_task() for why
 	 */
-	rpc_clnt_sigmask(clnt, &oldmask);
-	ret = out_of_line_wait_on_bit(&req->wb_flags, PG_BUSY,
-			nfs_wait_bit_interruptible, TASK_INTERRUPTIBLE);
-	rpc_clnt_sigunmask(clnt, &oldmask);
+	kfree(data);
+}
+EXPORT_SYMBOL_GPL(nfs_pgio_data_release);
+
+/**
+ * nfs_pgio_rpcsetup - Set up arguments for a pageio call
+ * @data: The pageio data
+ * @count: Number of bytes to read
+ * @offset: Initial offset
+ * @how: How to commit data (writes only)
+ * @cinfo: Commit information for the call (writes only)
+ */
+static void nfs_pgio_rpcsetup(struct nfs_pgio_data *data,
+			      unsigned int count, unsigned int offset,
+			      int how, struct nfs_commit_info *cinfo)
+{
+	struct nfs_page *req = data->header->req;
+
+	/* Set up the RPC argument and reply structs
+	 * NB: take care not to mess about with data->commit et al. */
+
+	data->args.fh     = NFS_FH(data->header->inode);
+	data->args.offset = req_offset(req) + offset;
+	/* pnfs_set_layoutcommit needs this */
+	data->mds_offset = data->args.offset;
+	data->args.pgbase = req->wb_pgbase + offset;
+	data->args.pages  = data->pages.pagevec;
+	data->args.count  = count;
+	data->args.context = get_nfs_open_context(req->wb_context);
+	data->args.lock_context = req->wb_lock_context;
+	data->args.stable  = NFS_UNSTABLE;
+	switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
+	case 0:
+		break;
+	case FLUSH_COND_STABLE:
+		if (nfs_reqs_to_commit(cinfo))
+			break;
+	default:
+		data->args.stable = NFS_FILE_SYNC;
+	}
+
+	data->res.fattr   = &data->fattr;
+	data->res.count   = count;
+	data->res.eof     = 0;
+	data->res.verf    = &data->verf;
+	nfs_fattr_init(&data->fattr);
+}
+
+/**
+ * nfs_pgio_prepare - Prepare pageio data to go over the wire
+ * @task: The current task
+ * @calldata: pageio data to prepare
+ */
+static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
+{
+	struct nfs_pgio_data *data = calldata;
+	int err;
+	err = NFS_PROTO(data->header->inode)->pgio_rpc_prepare(task, data);
+	if (err)
+		rpc_exit(task, err);
+}
+
+int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_data *data,
+		      const struct rpc_call_ops *call_ops, int how, int flags)
+{
+	struct rpc_task *task;
+	struct rpc_message msg = {
+		.rpc_argp = &data->args,
+		.rpc_resp = &data->res,
+		.rpc_cred = data->header->cred,
+	};
+	struct rpc_task_setup task_setup_data = {
+		.rpc_client = clnt,
+		.task = &data->task,
+		.rpc_message = &msg,
+		.callback_ops = call_ops,
+		.callback_data = data,
+		.workqueue = nfsiod_workqueue,
+		.flags = RPC_TASK_ASYNC | flags,
+	};
+	int ret = 0;
+
+	data->header->rw_ops->rw_initiate(data, &msg, &task_setup_data, how);
+
+	dprintk("NFS: %5u initiated pgio call "
+		"(req %s/%llu, %u bytes @ offset %llu)\n",
+		data->task.tk_pid,
+		data->header->inode->i_sb->s_id,
+		(unsigned long long)NFS_FILEID(data->header->inode),
+		data->args.count,
+		(unsigned long long)data->args.offset);
+
+	task = rpc_run_task(&task_setup_data);
+	if (IS_ERR(task)) {
+		ret = PTR_ERR(task);
+		goto out;
+	}
+	if (how & FLUSH_SYNC) {
+		ret = rpc_wait_for_completion_task(task);
+		if (ret == 0)
+			ret = task->tk_status;
+	}
+	rpc_put_task(task);
 out:
 	return ret;
 }
+EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
+
+/**
+ * nfs_pgio_error - Clean up from a pageio error
+ * @desc: IO descriptor
+ * @hdr: pageio header
+ */
+static int nfs_pgio_error(struct nfs_pageio_descriptor *desc,
+			  struct nfs_pgio_header *hdr)
+{
+	set_bit(NFS_IOHDR_REDO, &hdr->flags);
+	nfs_pgio_data_release(hdr->data);
+	hdr->data = NULL;
+	desc->pg_completion_ops->error_cleanup(&desc->pg_list);
+	return -ENOMEM;
+}
+
+/**
+ * nfs_pgio_release - Release pageio data
+ * @calldata: The pageio data to release
+ */
+static void nfs_pgio_release(void *calldata)
+{
+	struct nfs_pgio_data *data = calldata;
+	if (data->header->rw_ops->rw_release)
+		data->header->rw_ops->rw_release(data);
+	nfs_pgio_data_release(data);
+}
 
 /**
- * nfs_coalesce_requests - Split coalesced requests out from a list.
- * @head: source list
- * @dst: destination list
- * @nmax: maximum number of requests to coalesce
+ * nfs_pageio_init - initialise a page io descriptor
+ * @desc: pointer to descriptor
+ * @inode: pointer to inode
+ * @doio: pointer to io function
+ * @bsize: io block size
+ * @io_flags: extra parameters for the io function
+ */
+void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
+		     struct inode *inode,
+		     const struct nfs_pageio_ops *pg_ops,
+		     const struct nfs_pgio_completion_ops *compl_ops,
+		     const struct nfs_rw_ops *rw_ops,
+		     size_t bsize,
+		     int io_flags)
+{
+	INIT_LIST_HEAD(&desc->pg_list);
+	desc->pg_bytes_written = 0;
+	desc->pg_count = 0;
+	desc->pg_bsize = bsize;
+	desc->pg_base = 0;
+	desc->pg_moreio = 0;
+	desc->pg_recoalesce = 0;
+	desc->pg_inode = inode;
+	desc->pg_ops = pg_ops;
+	desc->pg_completion_ops = compl_ops;
+	desc->pg_rw_ops = rw_ops;
+	desc->pg_ioflags = io_flags;
+	desc->pg_error = 0;
+	desc->pg_lseg = NULL;
+	desc->pg_dreq = NULL;
+	desc->pg_layout_private = NULL;
+}
+EXPORT_SYMBOL_GPL(nfs_pageio_init);
+
+/**
+ * nfs_pgio_result - Basic pageio error handling
+ * @task: The task that ran
+ * @calldata: Pageio data to check
+ */
+static void nfs_pgio_result(struct rpc_task *task, void *calldata)
+{
+	struct nfs_pgio_data *data = calldata;
+	struct inode *inode = data->header->inode;
+
+	dprintk("NFS: %s: %5u, (status %d)\n", __func__,
+		task->tk_pid, task->tk_status);
+
+	if (data->header->rw_ops->rw_done(task, data, inode) != 0)
+		return;
+	if (task->tk_status < 0)
+		nfs_set_pgio_error(data->header, task->tk_status, data->args.offset);
+	else
+		data->header->rw_ops->rw_result(task, data);
+}
+
+/*
+ * Create an RPC task for the given read or write request and kick it.
+ * The page must have been locked by the caller.
  *
- * Moves a maximum of 'nmax' elements from one list to another.
- * The elements are checked to ensure that they form a contiguous set
- * of pages, and that the RPC credentials are the same.
+ * It may happen that the page we're passed is not marked dirty.
+ * This is the case if nfs_updatepage detects a conflicting request
+ * that has been written but not committed.
  */
-int
-nfs_coalesce_requests(struct list_head *head, struct list_head *dst,
-		      unsigned int nmax)
+int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
+		     struct nfs_pgio_header *hdr)
 {
-	struct nfs_page		*req = NULL;
-	unsigned int		npages = 0;
+	struct nfs_page		*req;
+	struct page		**pages;
+	struct nfs_pgio_data	*data;
+	struct list_head *head = &desc->pg_list;
+	struct nfs_commit_info cinfo;
 
-	while (!list_empty(head)) {
-		struct nfs_page	*prev = req;
+	data = nfs_pgio_data_alloc(hdr, nfs_page_array_len(desc->pg_base,
+							   desc->pg_count));
+	if (!data)
+		return nfs_pgio_error(desc, hdr);
 
+	nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
+	pages = data->pages.pagevec;
+	while (!list_empty(head)) {
 		req = nfs_list_entry(head->next);
-		if (prev) {
-			if (req->wb_context->cred != prev->wb_context->cred)
-				break;
-			if (req->wb_context->lockowner != prev->wb_context->lockowner)
-				break;
-			if (req->wb_context->state != prev->wb_context->state)
-				break;
-			if (req->wb_index != (prev->wb_index + 1))
-				break;
-
-			if (req->wb_pgbase != 0)
-				break;
-		}
 		nfs_list_remove_request(req);
-		nfs_list_add_request(req, dst);
-		npages++;
-		if (req->wb_pgbase + req->wb_bytes != PAGE_CACHE_SIZE)
-			break;
-		if (npages >= nmax)
-			break;
+		nfs_list_add_request(req, &hdr->pages);
+		*pages++ = req->wb_page;
+	}
+
+	if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
+	    (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
+		desc->pg_ioflags &= ~FLUSH_COND_STABLE;
+
+	/* Set up the argument struct */
+	nfs_pgio_rpcsetup(data, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
+	hdr->data = data;
+	desc->pg_rpc_callops = &nfs_pgio_common_ops;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nfs_generic_pgio);
+
+static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
+{
+	struct nfs_rw_header *rw_hdr;
+	struct nfs_pgio_header *hdr;
+	int ret;
+
+	rw_hdr = nfs_rw_header_alloc(desc->pg_rw_ops);
+	if (!rw_hdr) {
+		desc->pg_completion_ops->error_cleanup(&desc->pg_list);
+		return -ENOMEM;
 	}
-	return npages;
+	hdr = &rw_hdr->header;
+	nfs_pgheader_init(desc, hdr, nfs_rw_header_free);
+	atomic_inc(&hdr->refcnt);
+	ret = nfs_generic_pgio(desc, hdr);
+	if (ret == 0)
+		ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
+					hdr->data, desc->pg_rpc_callops,
+					desc->pg_ioflags, 0);
+	if (atomic_dec_and_test(&hdr->refcnt))
+		hdr->completion_ops->completion(hdr);
+	return ret;
+}
+
+static bool nfs_match_open_context(const struct nfs_open_context *ctx1,
+		const struct nfs_open_context *ctx2)
+{
+	return ctx1->cred == ctx2->cred && ctx1->state == ctx2->state;
+}
+
+static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
+		const struct nfs_lock_context *l2)
+{
+	return l1->lockowner.l_owner == l2->lockowner.l_owner
+		&& l1->lockowner.l_pid == l2->lockowner.l_pid;
 }
 
-#define NFS_SCAN_MAXENTRIES 16
 /**
- * nfs_scan_lock_dirty - Scan the radix tree for dirty requests
- * @nfsi: NFS inode
- * @dst: Destination list
- * @idx_start: lower bound of page->index to scan
- * @npages: idx_start + npages sets the upper bound to scan.
+ * nfs_can_coalesce_requests - test two requests for compatibility
+ * @prev: pointer to nfs_page
+ * @req: pointer to nfs_page
  *
- * Moves elements from one of the inode request lists.
- * If the number of requests is set to 0, the entire address_space
- * starting at index idx_start, is scanned.
- * The requests are *not* checked to ensure that they form a contiguous set.
- * You must be holding the inode's req_lock when calling this function
+ * The nfs_page structures 'prev' and 'req' are compared to ensure that the
+ * page data area they describe is contiguous, and that their RPC
+ * credentials, NFSv4 open state, and lockowners are the same.
+ *
+ * Return 'true' if this is the case, else return 'false'.
  */
-int
-nfs_scan_lock_dirty(struct nfs_inode *nfsi, struct list_head *dst,
-	      unsigned long idx_start, unsigned int npages)
-{
-	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
-	struct nfs_page *req;
-	unsigned long idx_end;
-	int found, i;
-	int res;
-
-	res = 0;
-	if (npages == 0)
-		idx_end = ~0;
-	else
-		idx_end = idx_start + npages - 1;
+static bool nfs_can_coalesce_requests(struct nfs_page *prev,
+				      struct nfs_page *req,
+				      struct nfs_pageio_descriptor *pgio)
+{
+	size_t size;
 
-	for (;;) {
-		found = radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree,
-				(void **)&pgvec[0], idx_start, NFS_SCAN_MAXENTRIES,
-				NFS_PAGE_TAG_DIRTY);
-		if (found <= 0)
-			break;
-		for (i = 0; i < found; i++) {
-			req = pgvec[i];
-			if (req->wb_index > idx_end)
-				goto out;
-
-			idx_start = req->wb_index + 1;
-
-			if (nfs_set_page_writeback_locked(req)) {
-				radix_tree_tag_clear(&nfsi->nfs_page_tree,
-						req->wb_index, NFS_PAGE_TAG_DIRTY);
-				nfs_list_remove_request(req);
-				nfs_list_add_request(req, dst);
-				res++;
-			}
-		}
+	if (prev) {
+		if (!nfs_match_open_context(req->wb_context, prev->wb_context))
+			return false;
+		if (req->wb_context->dentry->d_inode->i_flock != NULL &&
+		    !nfs_match_lock_context(req->wb_lock_context,
+					    prev->wb_lock_context))
+			return false;
+		if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
+			return false;
 	}
-out:
-	return res;
+	size = pgio->pg_ops->pg_test(pgio, prev, req);
+	WARN_ON_ONCE(size > req->wb_bytes);
+	if (size && size < req->wb_bytes)
+		req->wb_bytes = size;
+	return size > 0;
 }
 
 /**
- * nfs_scan_list - Scan a list for matching requests
- * @head: One of the NFS inode request lists
- * @dst: Destination list
- * @idx_start: lower bound of page->index to scan
- * @npages: idx_start + npages sets the upper bound to scan.
+ * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
+ * @desc: destination io descriptor
+ * @req: request
  *
- * Moves elements from one of the inode request lists.
- * If the number of requests is set to 0, the entire address_space
- * starting at index idx_start, is scanned.
- * The requests are *not* checked to ensure that they form a contiguous set.
- * You must be holding the inode's req_lock when calling this function
+ * Returns true if the request 'req' was successfully coalesced into the
+ * existing list of pages 'desc'.
  */
-int
-nfs_scan_list(struct list_head *head, struct list_head *dst,
-	      unsigned long idx_start, unsigned int npages)
+static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
+				     struct nfs_page *req)
 {
-	struct list_head	*pos, *tmp;
-	struct nfs_page		*req;
-	unsigned long		idx_end;
-	int			res;
+	struct nfs_page *prev = NULL;
+	if (desc->pg_count != 0) {
+		prev = nfs_list_entry(desc->pg_list.prev);
+	} else {
+		if (desc->pg_ops->pg_init)
+			desc->pg_ops->pg_init(desc, req);
+		desc->pg_base = req->wb_pgbase;
+	}
+	if (!nfs_can_coalesce_requests(prev, req, desc))
+		return 0;
+	nfs_list_remove_request(req);
+	nfs_list_add_request(req, &desc->pg_list);
+	desc->pg_count += req->wb_bytes;
+	return 1;
+}
 
-	res = 0;
-	if (npages == 0)
-		idx_end = ~0;
-	else
-		idx_end = idx_start + npages - 1;
+/*
+ * Helper for nfs_pageio_add_request and nfs_pageio_complete
+ */
+static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
+{
+	if (!list_empty(&desc->pg_list)) {
+		int error = desc->pg_ops->pg_doio(desc);
+		if (error < 0)
+			desc->pg_error = error;
+		else
+			desc->pg_bytes_written += desc->pg_count;
+	}
+	if (list_empty(&desc->pg_list)) {
+		desc->pg_count = 0;
+		desc->pg_base = 0;
+	}
+}
 
-	list_for_each_safe(pos, tmp, head) {
+/**
+ * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
+ * @desc: destination io descriptor
+ * @req: request
+ *
+ * This may split a request into subrequests which are all part of the
+ * same page group.
+ *
+ * Returns true if the request 'req' was successfully coalesced into the
+ * existing list of pages 'desc'.
+ */
+static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
+			   struct nfs_page *req)
+{
+	struct nfs_page *subreq;
+	unsigned int bytes_left = 0;
+	unsigned int offset, pgbase;
 
-		req = nfs_list_entry(pos);
+	nfs_page_group_lock(req);
 
-		if (req->wb_index < idx_start)
+	subreq = req;
+	bytes_left = subreq->wb_bytes;
+	offset = subreq->wb_offset;
+	pgbase = subreq->wb_pgbase;
+
+	do {
+		if (!nfs_pageio_do_add_request(desc, subreq)) {
+			/* make sure pg_test call(s) did nothing */
+			WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
+			WARN_ON_ONCE(subreq->wb_offset != offset);
+			WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
+
+			nfs_page_group_unlock(req);
+			desc->pg_moreio = 1;
+			nfs_pageio_doio(desc);
+			if (desc->pg_error < 0)
+				return 0;
+			if (desc->pg_recoalesce)
+				return 0;
+			/* retry add_request for this subreq */
+			nfs_page_group_lock(req);
 			continue;
-		if (req->wb_index > idx_end)
+		}
+
+		/* check for buggy pg_test call(s) */
+		WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
+		WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
+		WARN_ON_ONCE(subreq->wb_bytes == 0);
+
+		bytes_left -= subreq->wb_bytes;
+		offset += subreq->wb_bytes;
+		pgbase += subreq->wb_bytes;
+
+		if (bytes_left) {
+			subreq = nfs_create_request(req->wb_context,
+					req->wb_page,
+					subreq, pgbase, bytes_left);
+			if (IS_ERR(subreq))
+				goto err_ptr;
+			nfs_lock_request(subreq);
+			subreq->wb_offset  = offset;
+			subreq->wb_index = req->wb_index;
+		}
+	} while (bytes_left > 0);
+
+	nfs_page_group_unlock(req);
+	return 1;
+err_ptr:
+	desc->pg_error = PTR_ERR(subreq);
+	nfs_page_group_unlock(req);
+	return 0;
+}
+
+static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
+{
+	LIST_HEAD(head);
+
+	do {
+		list_splice_init(&desc->pg_list, &head);
+		desc->pg_bytes_written -= desc->pg_count;
+		desc->pg_count = 0;
+		desc->pg_base = 0;
+		desc->pg_recoalesce = 0;
+		desc->pg_moreio = 0;
+
+		while (!list_empty(&head)) {
+			struct nfs_page *req;
+
+			req = list_first_entry(&head, struct nfs_page, wb_list);
+			nfs_list_remove_request(req);
+			if (__nfs_pageio_add_request(desc, req))
+				continue;
+			if (desc->pg_error < 0)
+				return 0;
 			break;
+		}
+	} while (desc->pg_recoalesce);
+	return 1;
+}
 
-		if (!nfs_set_page_writeback_locked(req))
-			continue;
-		nfs_list_remove_request(req);
-		nfs_list_add_request(req, dst);
-		res++;
+int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
+		struct nfs_page *req)
+{
+	int ret;
+
+	do {
+		ret = __nfs_pageio_add_request(desc, req);
+		if (ret)
+			break;
+		if (desc->pg_error < 0)
+			break;
+		ret = nfs_do_recoalesce(desc);
+	} while (ret);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nfs_pageio_add_request);
+
+/**
+ * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
+ * @desc: pointer to io descriptor
+ */
+void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
+{
+	for (;;) {
+		nfs_pageio_doio(desc);
+		if (!desc->pg_recoalesce)
+			break;
+		if (!nfs_do_recoalesce(desc))
+			break;
 	}
-	return res;
 }
+EXPORT_SYMBOL_GPL(nfs_pageio_complete);
 
-int nfs_init_nfspagecache(void)
+/**
+ * nfs_pageio_cond_complete - Conditional I/O completion
+ * @desc: pointer to io descriptor
+ * @index: page index
+ *
+ * It is important to ensure that processes don't try to take locks
+ * on non-contiguous ranges of pages as that might deadlock. This
+ * function should be called before attempting to wait on a locked
+ * nfs_page. It will complete the I/O if the page index 'index'
+ * is not contiguous with the existing list of pages in 'desc'.
+ */
+void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
+{
+	if (!list_empty(&desc->pg_list)) {
+		struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
+		if (index != prev->wb_index + 1)
+			nfs_pageio_complete(desc);
+	}
+}
+
+int __init nfs_init_nfspagecache(void)
 {
 	nfs_page_cachep = kmem_cache_create("nfs_page",
 					    sizeof(struct nfs_page),
 					    0, SLAB_HWCACHE_ALIGN,
-					    NULL, NULL);
+					    NULL);
 	if (nfs_page_cachep == NULL)
 		return -ENOMEM;
 
@@ -377,7 +1065,16 @@ int nfs_init_nfspagecache(void)
 
 void nfs_destroy_nfspagecache(void)
 {
-	if (kmem_cache_destroy(nfs_page_cachep))
-		printk(KERN_INFO "nfs_page: not all structures were freed\n");
+	kmem_cache_destroy(nfs_page_cachep);
 }
 
+static const struct rpc_call_ops nfs_pgio_common_ops = {
+	.rpc_call_prepare = nfs_pgio_prepare,
+	.rpc_call_done = nfs_pgio_result,
+	.rpc_release = nfs_pgio_release,
+};
+
+const struct nfs_pageio_ops nfs_pgio_rw_ops = {
+	.pg_test = nfs_generic_pg_test,
+	.pg_doio = nfs_generic_pg_pgios,
+};