X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=fs%2Fnfs%2Fdirect.c;fp=fs%2Fnfs%2Fdirect.c;h=bd21d7fde650a57722e8afbda83402d352b8e07a;hb=97bf2856c6014879bd04983a3e9dfcdac1e7fe85;hp=4e9b3a1b36c5cc1f38b7246f94933765b2376775;hpb=76828883507a47dae78837ab5dec5a5b4513c667;p=linux-2.6.git

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 4e9b3a1b3..bd21d7fde 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -7,11 +7,11 @@
  *
  * There are important applications whose performance or correctness
  * depends on uncached access to file data.  Database clusters
- * (multiple copies of the same instance running on separate hosts) 
+ * (multiple copies of the same instance running on separate hosts)
  * implement their own cache coherency protocol that subsumes file
- * system cache protocols.  Applications that process datasets 
- * considerably larger than the client's memory do not always benefit 
- * from a local cache.  A streaming video server, for instance, has no 
+ * system cache protocols.  Applications that process datasets
+ * considerably larger than the client's memory do not always benefit
+ * from a local cache.  A streaming video server, for instance, has no
  * need to cache the contents of a file.
  *
  * When an application requests uncached I/O, all read and write requests
@@ -34,10 +34,10 @@
  * 08 Jun 2003	Port to 2.5 APIs  --cel
  * 31 Mar 2004	Handle direct I/O without VFS support  --cel
  * 15 Sep 2004	Parallel async reads  --cel
+ * 04 May 2005	support O_DIRECT with aio  --cel
  *
  */
 
-#include <linux/config.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/kernel.h>
@@ -54,635 +54,697 @@
 #include <asm/uaccess.h>
 #include <asm/atomic.h>
 
+#include "iostat.h"
+
 #define NFSDBG_FACILITY		NFSDBG_VFS
-#define MAX_DIRECTIO_SIZE	(4096UL << PAGE_SHIFT)
 
-static void nfs_free_user_pages(struct page **pages, int npages, int do_dirty);
-static kmem_cache_t *nfs_direct_cachep;
+static struct kmem_cache *nfs_direct_cachep;
 
 /*
  * This represents a set of asynchronous requests that we're waiting on
  */
 struct nfs_direct_req {
 	struct kref		kref;		/* release manager */
-	struct list_head	list;		/* nfs_read_data structs */
-	wait_queue_head_t	wait;		/* wait for i/o completion */
-	struct page **		pages;		/* pages in our buffer */
-	unsigned int		npages;		/* count of pages */
-	atomic_t		complete,	/* i/os we're waiting for */
-				count,		/* bytes actually processed */
+
+	/* I/O parameters */
+	struct nfs_open_context	*ctx;		/* file open context info */
+	struct kiocb *		iocb;		/* controlling i/o request */
+	struct inode *		inode;		/* target file of i/o */
+
+	/* completion state */
+	atomic_t		io_count;	/* i/os we're waiting for */
+	spinlock_t		lock;		/* protect completion state */
+	ssize_t			count,		/* bytes actually processed */
 				error;		/* any reported error */
+	struct completion	completion;	/* wait for i/o completion */
+
+	/* commit state */
+	struct list_head	rewrite_list;	/* saved nfs_write_data structs */
+	struct nfs_write_data *	commit_data;	/* special write_data for commits */
+	int			flags;
+#define NFS_ODIRECT_DO_COMMIT		(1)	/* an unstable reply was received */
+#define NFS_ODIRECT_RESCHED_WRITES	(2)	/* write verification failed */
+	struct nfs_writeverf	verf;		/* unstable write verifier */
 };
 
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
+static const struct rpc_call_ops nfs_write_direct_ops;
 
-/**
- * nfs_get_user_pages - find and set up pages underlying user's buffer
- * rw: direction (read or write)
- * user_addr: starting address of this segment of user's buffer
- * count: size of this segment
- * @pages: returned array of page struct pointers underlying user's buffer
- */
-static inline int
-nfs_get_user_pages(int rw, unsigned long user_addr, size_t size,
-		struct page ***pages)
+static inline void get_dreq(struct nfs_direct_req *dreq)
 {
-	int result = -ENOMEM;
-	unsigned long page_count;
-	size_t array_size;
-
-	/* set an arbitrary limit to prevent type overflow */
-	/* XXX: this can probably be as large as INT_MAX */
-	if (size > MAX_DIRECTIO_SIZE) {
-		*pages = NULL;
-		return -EFBIG;
-	}
-
-	page_count = (user_addr + size + PAGE_SIZE - 1) >> PAGE_SHIFT;
-	page_count -= user_addr >> PAGE_SHIFT;
+	atomic_inc(&dreq->io_count);
+}
 
-	array_size = (page_count * sizeof(struct page *));
-	*pages = kmalloc(array_size, GFP_KERNEL);
-	if (*pages) {
-		down_read(&current->mm->mmap_sem);
-		result = get_user_pages(current, current->mm, user_addr,
-					page_count, (rw == READ), 0,
-					*pages, NULL);
-		up_read(&current->mm->mmap_sem);
-		/*
-		 * If we got fewer pages than expected from get_user_pages(),
-		 * the user buffer runs off the end of a mapping; return EFAULT.
-		 */
-		if (result >= 0 && result < page_count) {
-			nfs_free_user_pages(*pages, result, 0);
-			*pages = NULL;
-			result = -EFAULT;
-		}
-	}
-	return result;
+static inline int put_dreq(struct nfs_direct_req *dreq)
+{
+	return atomic_dec_and_test(&dreq->io_count);
 }
 
 /**
- * nfs_free_user_pages - tear down page struct array
- * @pages: array of page struct pointers underlying target buffer
- * @npages: number of pages in the array
- * @do_dirty: dirty the pages as we release them
+ * nfs_direct_IO - NFS address space operation for direct I/O
+ * @rw: direction (read or write)
+ * @iocb: target I/O control block
+ * @iov: array of vectors that define I/O buffer
+ * @pos: offset in file to begin the operation
+ * @nr_segs: size of iovec array
+ *
+ * The presence of this routine in the address space ops vector means
+ * the NFS client supports direct I/O.  However, we shunt off direct
+ * read and write requests before the VFS gets them, so this method
+ * should never be called.
  */
-static void
-nfs_free_user_pages(struct page **pages, int npages, int do_dirty)
+ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
+{
+	dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
+			iocb->ki_filp->f_path.dentry->d_name.name,
+			(long long) pos, nr_segs);
+
+	return -EINVAL;
+}
+
+static void nfs_direct_dirty_pages(struct page **pages, int npages)
 {
 	int i;
 	for (i = 0; i < npages; i++) {
 		struct page *page = pages[i];
-		if (do_dirty && !PageCompound(page))
+		if (!PageCompound(page))
 			set_page_dirty_lock(page);
-		page_cache_release(page);
 	}
-	kfree(pages);
 }
 
-/**
- * nfs_direct_req_release - release  nfs_direct_req structure for direct read
- * @kref: kref object embedded in an nfs_direct_req structure
- *
- */
-static void nfs_direct_req_release(struct kref *kref)
+static void nfs_direct_release_pages(struct page **pages, int npages)
 {
-	struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
-	kmem_cache_free(nfs_direct_cachep, dreq);
+	int i;
+	for (i = 0; i < npages; i++)
+		page_cache_release(pages[i]);
 }
 
-/**
- * nfs_direct_read_alloc - allocate nfs_read_data structures for direct read
- * @count: count of bytes for the read request
- * @rsize: local rsize setting
- *
- * Note we also set the number of requests we have in the dreq when we are
- * done.  This prevents races with I/O completion so we will always wait
- * until all requests have been dispatched and completed.
- */
-static struct nfs_direct_req *nfs_direct_read_alloc(size_t nbytes, unsigned int rsize)
+static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
 {
-	struct list_head *list;
 	struct nfs_direct_req *dreq;
-	unsigned int reads = 0;
-	unsigned int rpages = (rsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 
-	dreq = kmem_cache_alloc(nfs_direct_cachep, SLAB_KERNEL);
+	dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
 	if (!dreq)
 		return NULL;
 
 	kref_init(&dreq->kref);
-	init_waitqueue_head(&dreq->wait);
-	INIT_LIST_HEAD(&dreq->list);
-	atomic_set(&dreq->count, 0);
-	atomic_set(&dreq->error, 0);
-
-	list = &dreq->list;
-	for(;;) {
-		struct nfs_read_data *data = nfs_readdata_alloc(rpages);
-
-		if (unlikely(!data)) {
-			while (!list_empty(list)) {
-				data = list_entry(list->next,
-						  struct nfs_read_data, pages);
-				list_del(&data->pages);
-				nfs_readdata_free(data);
-			}
-			kref_put(&dreq->kref, nfs_direct_req_release);
-			return NULL;
-		}
+	kref_get(&dreq->kref);
+	init_completion(&dreq->completion);
+	INIT_LIST_HEAD(&dreq->rewrite_list);
+	dreq->iocb = NULL;
+	dreq->ctx = NULL;
+	spin_lock_init(&dreq->lock);
+	atomic_set(&dreq->io_count, 0);
+	dreq->count = 0;
+	dreq->error = 0;
+	dreq->flags = 0;
 
-		INIT_LIST_HEAD(&data->pages);
-		list_add(&data->pages, list);
+	return dreq;
+}
 
-		data->req = (struct nfs_page *) dreq;
-		reads++;
-		if (nbytes <= rsize)
-			break;
-		nbytes -= rsize;
+static void nfs_direct_req_release(struct kref *kref)
+{
+	struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
+
+	if (dreq->ctx != NULL)
+		put_nfs_open_context(dreq->ctx);
+	kmem_cache_free(nfs_direct_cachep, dreq);
+}
+
+/*
+ * Collects and returns the final error value/byte-count.
+ */
+static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
+{
+	ssize_t result = -EIOCBQUEUED;
+
+	/* Async requests don't wait here */
+	if (dreq->iocb)
+		goto out;
+
+	result = wait_for_completion_interruptible(&dreq->completion);
+
+	if (!result)
+		result = dreq->error;
+	if (!result)
+		result = dreq->count;
+
+out:
+	kref_put(&dreq->kref, nfs_direct_req_release);
+	return (ssize_t) result;
+}
+
+/*
+ * Synchronous I/O uses a stack-allocated iocb.  Thus we can't trust
+ * the iocb is still valid here if this is a synchronous request.
+ */
+static void nfs_direct_complete(struct nfs_direct_req *dreq)
+{
+	if (dreq->iocb) {
+		long res = (long) dreq->error;
+		if (!res)
+			res = (long) dreq->count;
+		aio_complete(dreq->iocb, res, 0);
 	}
-	kref_get(&dreq->kref);
-	atomic_set(&dreq->complete, reads);
-	return dreq;
+	complete_all(&dreq->completion);
+
+	kref_put(&dreq->kref, nfs_direct_req_release);
 }
 
-/**
- * nfs_direct_read_result - handle a read reply for a direct read request
- * @data: address of NFS READ operation control block
- * @status: status of this NFS READ operation
- *
+/*
  * We must hold a reference to all the pages in this direct read request
  * until the RPCs complete.  This could be long *after* we are woken up in
- * nfs_direct_read_wait (for instance, if someone hits ^C on a slow server).
+ * nfs_direct_wait (for instance, if someone hits ^C on a slow server).
  */
-static void nfs_direct_read_result(struct nfs_read_data *data, int status)
+static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
 {
+	struct nfs_read_data *data = calldata;
 	struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 
-	if (likely(status >= 0))
-		atomic_add(data->res.count, &dreq->count);
+	if (nfs_readpage_result(task, data) != 0)
+		return;
+
+	nfs_direct_dirty_pages(data->pagevec, data->npages);
+	nfs_direct_release_pages(data->pagevec, data->npages);
+
+	spin_lock(&dreq->lock);
+
+	if (likely(task->tk_status >= 0))
+		dreq->count += data->res.count;
 	else
-		atomic_set(&dreq->error, status);
+		dreq->error = task->tk_status;
 
-	if (unlikely(atomic_dec_and_test(&dreq->complete))) {
-		nfs_free_user_pages(dreq->pages, dreq->npages, 1);
-		wake_up(&dreq->wait);
-		kref_put(&dreq->kref, nfs_direct_req_release);
-	}
+	spin_unlock(&dreq->lock);
+
+	if (put_dreq(dreq))
+		nfs_direct_complete(dreq);
 }
 
-/**
- * nfs_direct_read_schedule - dispatch NFS READ operations for a direct read
- * @dreq: address of nfs_direct_req struct for this request
- * @inode: target inode
- * @ctx: target file open context
- * @user_addr: starting address of this segment of user's buffer
- * @count: size of this segment
- * @file_offset: offset in file to begin the operation
- *
- * For each nfs_read_data struct that was allocated on the list, dispatch
- * an NFS READ operation
+static const struct rpc_call_ops nfs_read_direct_ops = {
+	.rpc_call_done = nfs_direct_read_result,
+	.rpc_release = nfs_readdata_release,
+};
+
+/*
+ * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
+ * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
+ * bail and stop sending more reads.  Read length accounting is
+ * handled automatically by nfs_direct_read_result().  Otherwise, if
+ * no requests have been sent, just return an error.
  */
-static void nfs_direct_read_schedule(struct nfs_direct_req *dreq,
-		struct inode *inode, struct nfs_open_context *ctx,
-		unsigned long user_addr, size_t count, loff_t file_offset)
+static ssize_t nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos)
 {
-	struct list_head *list = &dreq->list;
-	struct page **pages = dreq->pages;
-	unsigned int curpage, pgbase;
-	unsigned int rsize = NFS_SERVER(inode)->rsize;
+	struct nfs_open_context *ctx = dreq->ctx;
+	struct inode *inode = ctx->dentry->d_inode;
+	size_t rsize = NFS_SERVER(inode)->rsize;
+	unsigned int pgbase;
+	int result;
+	ssize_t started = 0;
+
+	get_dreq(dreq);
 
-	curpage = 0;
-	pgbase = user_addr & ~PAGE_MASK;
 	do {
 		struct nfs_read_data *data;
-		unsigned int bytes;
+		size_t bytes;
 
-		bytes = rsize;
-		if (count < rsize)
-			bytes = count;
+		pgbase = user_addr & ~PAGE_MASK;
+		bytes = min(rsize,count);
 
-		data = list_entry(list->next, struct nfs_read_data, pages);
-		list_del_init(&data->pages);
+		result = -ENOMEM;
+		data = nfs_readdata_alloc(pgbase + bytes);
+		if (unlikely(!data))
+			break;
 
+		down_read(&current->mm->mmap_sem);
+		result = get_user_pages(current, current->mm, user_addr,
+					data->npages, 1, 0, data->pagevec, NULL);
+		up_read(&current->mm->mmap_sem);
+		if (unlikely(result < data->npages)) {
+			if (result > 0)
+				nfs_direct_release_pages(data->pagevec, result);
+			nfs_readdata_release(data);
+			break;
+		}
+
+		get_dreq(dreq);
+
+		data->req = (struct nfs_page *) dreq;
 		data->inode = inode;
 		data->cred = ctx->cred;
 		data->args.fh = NFS_FH(inode);
 		data->args.context = ctx;
-		data->args.offset = file_offset;
+		data->args.offset = pos;
 		data->args.pgbase = pgbase;
-		data->args.pages = &pages[curpage];
+		data->args.pages = data->pagevec;
 		data->args.count = bytes;
 		data->res.fattr = &data->fattr;
 		data->res.eof = 0;
 		data->res.count = bytes;
 
+		rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
+				&nfs_read_direct_ops, data);
 		NFS_PROTO(inode)->read_setup(data);
 
 		data->task.tk_cookie = (unsigned long) inode;
-		data->complete = nfs_direct_read_result;
 
-		lock_kernel();
 		rpc_execute(&data->task);
-		unlock_kernel();
 
-		dfprintk(VFS, "NFS: %4d initiated direct read call (req %s/%Ld, %u bytes @ offset %Lu)\n",
+		dfprintk(VFS, "NFS: %5u initiated direct read call (req %s/%Ld, %zu bytes @ offset %Lu)\n",
 				data->task.tk_pid,
 				inode->i_sb->s_id,
 				(long long)NFS_FILEID(inode),
 				bytes,
 				(unsigned long long)data->args.offset);
 
-		file_offset += bytes;
+		started += bytes;
+		user_addr += bytes;
+		pos += bytes;
+		/* FIXME: Remove this unnecessary math from final patch */
 		pgbase += bytes;
-		curpage += pgbase >> PAGE_SHIFT;
 		pgbase &= ~PAGE_MASK;
+		BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
 
 		count -= bytes;
 	} while (count != 0);
-}
 
-/**
- * nfs_direct_read_wait - wait for I/O completion for direct reads
- * @dreq: request on which we are to wait
- * @intr: whether or not this wait can be interrupted
- *
- * Collects and returns the final error value/byte-count.
- */
-static ssize_t nfs_direct_read_wait(struct nfs_direct_req *dreq, int intr)
-{
-	int result = 0;
-
-	if (intr) {
-		result = wait_event_interruptible(dreq->wait,
-					(atomic_read(&dreq->complete) == 0));
-	} else {
-		wait_event(dreq->wait, (atomic_read(&dreq->complete) == 0));
-	}
-
-	if (!result)
-		result = atomic_read(&dreq->error);
-	if (!result)
-		result = atomic_read(&dreq->count);
+	if (put_dreq(dreq))
+		nfs_direct_complete(dreq);
 
-	kref_put(&dreq->kref, nfs_direct_req_release);
-	return (ssize_t) result;
+	if (started)
+		return 0;
+	return result < 0 ? (ssize_t) result : -EFAULT;
 }
 
-/**
- * nfs_direct_read_seg - Read in one iov segment.  Generate separate
- *                        read RPCs for each "rsize" bytes.
- * @inode: target inode
- * @ctx: target file open context
- * @user_addr: starting address of this segment of user's buffer
- * @count: size of this segment
- * @file_offset: offset in file to begin the operation
- * @pages: array of addresses of page structs defining user's buffer
- * @nr_pages: number of pages in the array
- *
- */
-static ssize_t nfs_direct_read_seg(struct inode *inode,
-		struct nfs_open_context *ctx, unsigned long user_addr,
-		size_t count, loff_t file_offset, struct page **pages,
-		unsigned int nr_pages)
+static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
 {
-	ssize_t result;
+	ssize_t result = 0;
 	sigset_t oldset;
+	struct inode *inode = iocb->ki_filp->f_mapping->host;
 	struct rpc_clnt *clnt = NFS_CLIENT(inode);
 	struct nfs_direct_req *dreq;
 
-	dreq = nfs_direct_read_alloc(count, NFS_SERVER(inode)->rsize);
+	dreq = nfs_direct_req_alloc();
 	if (!dreq)
 		return -ENOMEM;
 
-	dreq->pages = pages;
-	dreq->npages = nr_pages;
+	dreq->inode = inode;
+	dreq->ctx = get_nfs_open_context((struct nfs_open_context *)iocb->ki_filp->private_data);
+	if (!is_sync_kiocb(iocb))
+		dreq->iocb = iocb;
 
+	nfs_add_stats(inode, NFSIOS_DIRECTREADBYTES, count);
 	rpc_clnt_sigmask(clnt, &oldset);
-	nfs_direct_read_schedule(dreq, inode, ctx, user_addr, count,
-				 file_offset);
-	result = nfs_direct_read_wait(dreq, clnt->cl_intr);
+	result = nfs_direct_read_schedule(dreq, user_addr, count, pos);
+	if (!result)
+		result = nfs_direct_wait(dreq);
 	rpc_clnt_sigunmask(clnt, &oldset);
 
 	return result;
 }
 
-/**
- * nfs_direct_read - For each iov segment, map the user's buffer
- *                   then generate read RPCs.
- * @inode: target inode
- * @ctx: target file open context
- * @iov: array of vectors that define I/O buffer
- * file_offset: offset in file to begin the operation
- * nr_segs: size of iovec array
- *
- * We've already pushed out any non-direct writes so that this read
- * will see them when we read from the server.
- */
-static ssize_t
-nfs_direct_read(struct inode *inode, struct nfs_open_context *ctx,
-		const struct iovec *iov, loff_t file_offset,
-		unsigned long nr_segs)
+static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
 {
-	ssize_t tot_bytes = 0;
-	unsigned long seg = 0;
-
-	while ((seg < nr_segs) && (tot_bytes >= 0)) {
-		ssize_t result;
-		int page_count;
-		struct page **pages;
-		const struct iovec *vec = &iov[seg++];
-		unsigned long user_addr = (unsigned long) vec->iov_base;
-		size_t size = vec->iov_len;
-
-                page_count = nfs_get_user_pages(READ, user_addr, size, &pages);
-                if (page_count < 0) {
-                        nfs_free_user_pages(pages, 0, 0);
-			if (tot_bytes > 0)
-				break;
-                        return page_count;
-                }
+	while (!list_empty(&dreq->rewrite_list)) {
+		struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
+		list_del(&data->pages);
+		nfs_direct_release_pages(data->pagevec, data->npages);
+		nfs_writedata_release(data);
+	}
+}
 
-		result = nfs_direct_read_seg(inode, ctx, user_addr, size,
-				file_offset, pages, page_count);
+#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
+static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
+{
+	struct inode *inode = dreq->inode;
+	struct list_head *p;
+	struct nfs_write_data *data;
 
-		if (result <= 0) {
-			if (tot_bytes > 0)
-				break;
-			return result;
-		}
-		tot_bytes += result;
-		file_offset += result;
-		if (result < size)
-			break;
+	dreq->count = 0;
+	get_dreq(dreq);
+
+	list_for_each(p, &dreq->rewrite_list) {
+		data = list_entry(p, struct nfs_write_data, pages);
+
+		get_dreq(dreq);
+
+		/*
+		 * Reset data->res.
+		 */
+		nfs_fattr_init(&data->fattr);
+		data->res.count = data->args.count;
+		memset(&data->verf, 0, sizeof(data->verf));
+
+		/*
+		 * Reuse data->task; data->args should not have changed
+		 * since the original request was sent.
+		 */
+		rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
+				&nfs_write_direct_ops, data);
+		NFS_PROTO(inode)->write_setup(data, FLUSH_STABLE);
+
+		data->task.tk_priority = RPC_PRIORITY_NORMAL;
+		data->task.tk_cookie = (unsigned long) inode;
+
+		/*
+		 * We're called via an RPC callback, so BKL is already held.
+		 */
+		rpc_execute(&data->task);
+
+		dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
+				data->task.tk_pid,
+				inode->i_sb->s_id,
+				(long long)NFS_FILEID(inode),
+				data->args.count,
+				(unsigned long long)data->args.offset);
 	}
 
-	return tot_bytes;
+	if (put_dreq(dreq))
+		nfs_direct_write_complete(dreq, inode);
 }
 
-/**
- * nfs_direct_write_seg - Write out one iov segment.  Generate separate
- *                        write RPCs for each "wsize" bytes, then commit.
- * @inode: target inode
- * @ctx: target file open context
- * user_addr: starting address of this segment of user's buffer
- * count: size of this segment
- * file_offset: offset in file to begin the operation
- * @pages: array of addresses of page structs defining user's buffer
- * nr_pages: size of pages array
- */
-static ssize_t nfs_direct_write_seg(struct inode *inode,
-		struct nfs_open_context *ctx, unsigned long user_addr,
-		size_t count, loff_t file_offset, struct page **pages,
-		int nr_pages)
+static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
 {
-	const unsigned int wsize = NFS_SERVER(inode)->wsize;
-	size_t request;
-	int curpage, need_commit;
-	ssize_t result, tot_bytes;
-	struct nfs_writeverf first_verf;
-	struct nfs_write_data *wdata;
-
-	wdata = nfs_writedata_alloc(NFS_SERVER(inode)->wpages);
-	if (!wdata)
-		return -ENOMEM;
+	struct nfs_write_data *data = calldata;
+	struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 
-	wdata->inode = inode;
-	wdata->cred = ctx->cred;
-	wdata->args.fh = NFS_FH(inode);
-	wdata->args.context = ctx;
-	wdata->args.stable = NFS_UNSTABLE;
-	if (IS_SYNC(inode) || NFS_PROTO(inode)->version == 2 || count <= wsize)
-		wdata->args.stable = NFS_FILE_SYNC;
-	wdata->res.fattr = &wdata->fattr;
-	wdata->res.verf = &wdata->verf;
+	/* Call the NFS version-specific code */
+	if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
+		return;
+	if (unlikely(task->tk_status < 0)) {
+		dreq->error = task->tk_status;
+		dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+	}
+	if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
+		dprintk("NFS: %5u commit verify failed\n", task->tk_pid);
+		dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+	}
 
-	nfs_begin_data_update(inode);
-retry:
-	need_commit = 0;
-	tot_bytes = 0;
-	curpage = 0;
-	request = count;
-	wdata->args.pgbase = user_addr & ~PAGE_MASK;
-	wdata->args.offset = file_offset;
-	do {
-		wdata->args.count = request;
-		if (wdata->args.count > wsize)
-			wdata->args.count = wsize;
-		wdata->args.pages = &pages[curpage];
+	dprintk("NFS: %5u commit returned %d\n", task->tk_pid, task->tk_status);
+	nfs_direct_write_complete(dreq, data->inode);
+}
 
-		dprintk("NFS: direct write: c=%u o=%Ld ua=%lu, pb=%u, cp=%u\n",
-			wdata->args.count, (long long) wdata->args.offset,
-			user_addr + tot_bytes, wdata->args.pgbase, curpage);
+static const struct rpc_call_ops nfs_commit_direct_ops = {
+	.rpc_call_done = nfs_direct_commit_result,
+	.rpc_release = nfs_commit_release,
+};
 
-		lock_kernel();
-		result = NFS_PROTO(inode)->write(wdata);
-		unlock_kernel();
+static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
+{
+	struct nfs_write_data *data = dreq->commit_data;
 
-		if (result <= 0) {
-			if (tot_bytes > 0)
-				break;
-			goto out;
-		}
+	data->inode = dreq->inode;
+	data->cred = dreq->ctx->cred;
 
-		if (tot_bytes == 0)
-			memcpy(&first_verf.verifier, &wdata->verf.verifier,
-						sizeof(first_verf.verifier));
-		if (wdata->verf.committed != NFS_FILE_SYNC) {
-			need_commit = 1;
-			if (memcmp(&first_verf.verifier, &wdata->verf.verifier,
-					sizeof(first_verf.verifier)))
-				goto sync_retry;
-		}
+	data->args.fh = NFS_FH(data->inode);
+	data->args.offset = 0;
+	data->args.count = 0;
+	data->res.count = 0;
+	data->res.fattr = &data->fattr;
+	data->res.verf = &data->verf;
 
-		tot_bytes += result;
+	rpc_init_task(&data->task, NFS_CLIENT(dreq->inode), RPC_TASK_ASYNC,
+				&nfs_commit_direct_ops, data);
+	NFS_PROTO(data->inode)->commit_setup(data, 0);
 
-		/* in case of a short write: stop now, let the app recover */
-		if (result < wdata->args.count)
-			break;
+	data->task.tk_priority = RPC_PRIORITY_NORMAL;
+	data->task.tk_cookie = (unsigned long)data->inode;
+	/* Note: task.tk_ops->rpc_release will free dreq->commit_data */
+	dreq->commit_data = NULL;
+
+	dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
 
-		wdata->args.offset += result;
-		wdata->args.pgbase += result;
-		curpage += wdata->args.pgbase >> PAGE_SHIFT;
-		wdata->args.pgbase &= ~PAGE_MASK;
-		request -= result;
-	} while (request != 0);
-
-	/*
-	 * Commit data written so far, even in the event of an error
-	 */
-	if (need_commit) {
-		wdata->args.count = tot_bytes;
-		wdata->args.offset = file_offset;
-
-		lock_kernel();
-		result = NFS_PROTO(inode)->commit(wdata);
-		unlock_kernel();
-
-		if (result < 0 || memcmp(&first_verf.verifier,
-					 &wdata->verf.verifier,
-					 sizeof(first_verf.verifier)) != 0)
-			goto sync_retry;
+	rpc_execute(&data->task);
+}
+
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
+{
+	int flags = dreq->flags;
+
+	dreq->flags = 0;
+	switch (flags) {
+		case NFS_ODIRECT_DO_COMMIT:
+			nfs_direct_commit_schedule(dreq);
+			break;
+		case NFS_ODIRECT_RESCHED_WRITES:
+			nfs_direct_write_reschedule(dreq);
+			break;
+		default:
+			nfs_end_data_update(inode);
+			if (dreq->commit_data != NULL)
+				nfs_commit_free(dreq->commit_data);
+			nfs_direct_free_writedata(dreq);
+			nfs_zap_mapping(inode, inode->i_mapping);
+			nfs_direct_complete(dreq);
 	}
-	result = tot_bytes;
+}
 
-out:
-	nfs_end_data_update(inode);
-	nfs_writedata_free(wdata);
-	return result;
+static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
+{
+	dreq->commit_data = nfs_commit_alloc();
+	if (dreq->commit_data != NULL)
+		dreq->commit_data->req = (struct nfs_page *) dreq;
+}
+#else
+static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
+{
+	dreq->commit_data = NULL;
+}
 
-sync_retry:
-	wdata->args.stable = NFS_FILE_SYNC;
-	goto retry;
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
+{
+	nfs_end_data_update(inode);
+	nfs_direct_free_writedata(dreq);
+	nfs_zap_mapping(inode, inode->i_mapping);
+	nfs_direct_complete(dreq);
 }
+#endif
 
-/**
- * nfs_direct_write - For each iov segment, map the user's buffer
- *                    then generate write and commit RPCs.
- * @inode: target inode
- * @ctx: target file open context
- * @iov: array of vectors that define I/O buffer
- * file_offset: offset in file to begin the operation
- * nr_segs: size of iovec array
- *
- * Upon return, generic_file_direct_IO invalidates any cached pages
- * that non-direct readers might access, so they will pick up these
- * writes immediately.
- */
-static ssize_t nfs_direct_write(struct inode *inode,
-		struct nfs_open_context *ctx, const struct iovec *iov,
-		loff_t file_offset, unsigned long nr_segs)
+static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
 {
-	ssize_t tot_bytes = 0;
-	unsigned long seg = 0;
-
-	while ((seg < nr_segs) && (tot_bytes >= 0)) {
-		ssize_t result;
-		int page_count;
-		struct page **pages;
-		const struct iovec *vec = &iov[seg++];
-		unsigned long user_addr = (unsigned long) vec->iov_base;
-		size_t size = vec->iov_len;
-
-                page_count = nfs_get_user_pages(WRITE, user_addr, size, &pages);
-                if (page_count < 0) {
-                        nfs_free_user_pages(pages, 0, 0);
-			if (tot_bytes > 0)
-				break;
-                        return page_count;
-                }
+	struct nfs_write_data *data = calldata;
+	struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
+	int status = task->tk_status;
+
+	if (nfs_writeback_done(task, data) != 0)
+		return;
+
+	spin_lock(&dreq->lock);
+
+	if (unlikely(status < 0)) {
+		dreq->error = status;
+		goto out_unlock;
+	}
 
-		result = nfs_direct_write_seg(inode, ctx, user_addr, size,
-				file_offset, pages, page_count);
-		nfs_free_user_pages(pages, page_count, 0);
+	dreq->count += data->res.count;
 
-		if (result <= 0) {
-			if (tot_bytes > 0)
+	if (data->res.verf->committed != NFS_FILE_SYNC) {
+		switch (dreq->flags) {
+			case 0:
+				memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
+				dreq->flags = NFS_ODIRECT_DO_COMMIT;
 				break;
-			return result;
+			case NFS_ODIRECT_DO_COMMIT:
+				if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
+					dprintk("NFS: %5u write verify failed\n", task->tk_pid);
+					dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+				}
 		}
-		tot_bytes += result;
-		file_offset += result;
-		if (result < size)
-			break;
 	}
-	return tot_bytes;
+out_unlock:
+	spin_unlock(&dreq->lock);
 }
 
-/**
- * nfs_direct_IO - NFS address space operation for direct I/O
- * rw: direction (read or write)
- * @iocb: target I/O control block
- * @iov: array of vectors that define I/O buffer
- * file_offset: offset in file to begin the operation
- * nr_segs: size of iovec array
- *
+/*
+ * NB: Return the value of the first error return code.  Subsequent
+ *     errors after the first one are ignored.
  */
-ssize_t
-nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
-		loff_t file_offset, unsigned long nr_segs)
+static void nfs_direct_write_release(void *calldata)
 {
-	ssize_t result = -EINVAL;
-	struct file *file = iocb->ki_filp;
-	struct nfs_open_context *ctx;
-	struct dentry *dentry = file->f_dentry;
-	struct inode *inode = dentry->d_inode;
+	struct nfs_write_data *data = calldata;
+	struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 
-	/*
-	 * No support for async yet
-	 */
+	if (put_dreq(dreq))
+		nfs_direct_write_complete(dreq, data->inode);
+}
+
+static const struct rpc_call_ops nfs_write_direct_ops = {
+	.rpc_call_done = nfs_direct_write_result,
+	.rpc_release = nfs_direct_write_release,
+};
+
+/*
+ * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
+ * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
+ * bail and stop sending more writes.  Write length accounting is
+ * handled automatically by nfs_direct_write_result().  Otherwise, if
+ * no requests have been sent, just return an error.
+ */
+static ssize_t nfs_direct_write_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos, int sync)
+{
+	struct nfs_open_context *ctx = dreq->ctx;
+	struct inode *inode = ctx->dentry->d_inode;
+	size_t wsize = NFS_SERVER(inode)->wsize;
+	unsigned int pgbase;
+	int result;
+	ssize_t started = 0;
+
+	get_dreq(dreq);
+
+	do {
+		struct nfs_write_data *data;
+		size_t bytes;
+
+		pgbase = user_addr & ~PAGE_MASK;
+		bytes = min(wsize,count);
+
+		result = -ENOMEM;
+		data = nfs_writedata_alloc(pgbase + bytes);
+		if (unlikely(!data))
+			break;
+
+		down_read(&current->mm->mmap_sem);
+		result = get_user_pages(current, current->mm, user_addr,
+					data->npages, 0, 0, data->pagevec, NULL);
+		up_read(&current->mm->mmap_sem);
+		if (unlikely(result < data->npages)) {
+			if (result > 0)
+				nfs_direct_release_pages(data->pagevec, result);
+			nfs_writedata_release(data);
+			break;
+		}
+
+		get_dreq(dreq);
+
+		list_move_tail(&data->pages, &dreq->rewrite_list);
+
+		data->req = (struct nfs_page *) dreq;
+		data->inode = inode;
+		data->cred = ctx->cred;
+		data->args.fh = NFS_FH(inode);
+		data->args.context = ctx;
+		data->args.offset = pos;
+		data->args.pgbase = pgbase;
+		data->args.pages = data->pagevec;
+		data->args.count = bytes;
+		data->res.fattr = &data->fattr;
+		data->res.count = bytes;
+		data->res.verf = &data->verf;
+
+		rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC,
+				&nfs_write_direct_ops, data);
+		NFS_PROTO(inode)->write_setup(data, sync);
+
+		data->task.tk_priority = RPC_PRIORITY_NORMAL;
+		data->task.tk_cookie = (unsigned long) inode;
+
+		rpc_execute(&data->task);
+
+		dfprintk(VFS, "NFS: %5u initiated direct write call (req %s/%Ld, %zu bytes @ offset %Lu)\n",
+				data->task.tk_pid,
+				inode->i_sb->s_id,
+				(long long)NFS_FILEID(inode),
+				bytes,
+				(unsigned long long)data->args.offset);
+
+		started += bytes;
+		user_addr += bytes;
+		pos += bytes;
+
+		/* FIXME: Remove this useless math from the final patch */
+		pgbase += bytes;
+		pgbase &= ~PAGE_MASK;
+		BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
+
+		count -= bytes;
+	} while (count != 0);
+
+	if (put_dreq(dreq))
+		nfs_direct_write_complete(dreq, inode);
+
+	if (started)
+		return 0;
+	return result < 0 ? (ssize_t) result : -EFAULT;
+}
+
+static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
+{
+	ssize_t result = 0;
+	sigset_t oldset;
+	struct inode *inode = iocb->ki_filp->f_mapping->host;
+	struct rpc_clnt *clnt = NFS_CLIENT(inode);
+	struct nfs_direct_req *dreq;
+	size_t wsize = NFS_SERVER(inode)->wsize;
+	int sync = 0;
+
+	dreq = nfs_direct_req_alloc();
+	if (!dreq)
+		return -ENOMEM;
+	nfs_alloc_commit_data(dreq);
+
+	if (dreq->commit_data == NULL || count < wsize)
+		sync = FLUSH_STABLE;
+
+	dreq->inode = inode;
+	dreq->ctx = get_nfs_open_context((struct nfs_open_context *)iocb->ki_filp->private_data);
 	if (!is_sync_kiocb(iocb))
-		return result;
-
-	ctx = (struct nfs_open_context *)file->private_data;
-	switch (rw) {
-	case READ:
-		dprintk("NFS: direct_IO(read) (%s) off/no(%Lu/%lu)\n",
-				dentry->d_name.name, file_offset, nr_segs);
-
-		result = nfs_direct_read(inode, ctx, iov,
-						file_offset, nr_segs);
-		break;
-	case WRITE:
-		dprintk("NFS: direct_IO(write) (%s) off/no(%Lu/%lu)\n",
-				dentry->d_name.name, file_offset, nr_segs);
-
-		result = nfs_direct_write(inode, ctx, iov,
-						file_offset, nr_segs);
-		break;
-	default:
-		break;
-	}
+		dreq->iocb = iocb;
+
+	nfs_add_stats(inode, NFSIOS_DIRECTWRITTENBYTES, count);
+
+	nfs_begin_data_update(inode);
+
+	rpc_clnt_sigmask(clnt, &oldset);
+	result = nfs_direct_write_schedule(dreq, user_addr, count, pos, sync);
+	if (!result)
+		result = nfs_direct_wait(dreq);
+	rpc_clnt_sigunmask(clnt, &oldset);
+
 	return result;
 }
 
 /**
  * nfs_file_direct_read - file direct read operation for NFS files
  * @iocb: target I/O control block
- * @buf: user's buffer into which to read data
- * count: number of bytes to read
- * pos: byte offset in file where reading starts
+ * @iov: vector of user buffers into which to read data
+ * @nr_segs: size of iov vector
+ * @pos: byte offset in file where reading starts
  *
  * We use this function for direct reads instead of calling
  * generic_file_aio_read() in order to avoid gfar's check to see if
  * the request starts before the end of the file.  For that check
  * to work, we must generate a GETATTR before each direct read, and
  * even then there is a window between the GETATTR and the subsequent
- * READ where the file size could change.  So our preference is simply
+ * READ where the file size could change.  Our preference is simply
  * to do all reads the application wants, and the server will take
  * care of managing the end of file boundary.
- * 
+ *
  * This function also eliminates unnecessarily updating the file's
  * atime locally, as the NFS server sets the file's atime, and this
  * client must read the updated atime from the server back into its
  * cache.
  */
-ssize_t
-nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
+ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
+				unsigned long nr_segs, loff_t pos)
 {
 	ssize_t retval = -EINVAL;
-	loff_t *ppos = &iocb->ki_pos;
 	struct file *file = iocb->ki_filp;
-	struct nfs_open_context *ctx =
-			(struct nfs_open_context *) file->private_data;
 	struct address_space *mapping = file->f_mapping;
-	struct inode *inode = mapping->host;
-	struct iovec iov = {
-		.iov_base = buf,
-		.iov_len = count,
-	};
+	/* XXX: temporary */
+	const char __user *buf = iov[0].iov_base;
+	size_t count = iov[0].iov_len;
 
 	dprintk("nfs: direct read(%s/%s, %lu@%Ld)\n",
-		file->f_dentry->d_parent->d_name.name,
-		file->f_dentry->d_name.name,
+		file->f_path.dentry->d_parent->d_name.name,
+		file->f_path.dentry->d_name.name,
 		(unsigned long) count, (long long) pos);
 
-	if (!is_sync_kiocb(iocb))
-		goto out;
+	if (nr_segs != 1)
+		return -EINVAL;
+
 	if (count < 0)
 		goto out;
 	retval = -EFAULT;
-	if (!access_ok(VERIFY_WRITE, iov.iov_base, iov.iov_len))
+	if (!access_ok(VERIFY_WRITE, buf, count))
 		goto out;
 	retval = 0;
 	if (!count)
@@ -692,9 +754,9 @@ nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t
 	if (retval)
 		goto out;
 
-	retval = nfs_direct_read(inode, ctx, &iov, pos, 1);
+	retval = nfs_direct_read(iocb, (unsigned long) buf, count, pos);
 	if (retval > 0)
-		*ppos = pos + retval;
+		iocb->ki_pos = pos + retval;
 
 out:
 	return retval;
@@ -703,9 +765,9 @@ out:
 /**
  * nfs_file_direct_write - file direct write operation for NFS files
  * @iocb: target I/O control block
- * @buf: user's buffer from which to write data
- * count: number of bytes to write
- * pos: byte offset in file where writing starts
+ * @iov: vector of user buffers from which to write data
+ * @nr_segs: size of iov vector
+ * @pos: byte offset in file where writing starts
  *
  * We use this function for direct writes instead of calling
  * generic_file_aio_write() in order to avoid taking the inode
@@ -725,27 +787,23 @@ out:
  * Note that O_APPEND is not supported for NFS direct writes, as there
  * is no atomic O_APPEND write facility in the NFS protocol.
  */
-ssize_t
-nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t count, loff_t pos)
+ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
+				unsigned long nr_segs, loff_t pos)
 {
 	ssize_t retval;
 	struct file *file = iocb->ki_filp;
-	struct nfs_open_context *ctx =
-			(struct nfs_open_context *) file->private_data;
 	struct address_space *mapping = file->f_mapping;
-	struct inode *inode = mapping->host;
-	struct iovec iov = {
-		.iov_base = (char __user *)buf,
-	};
+	/* XXX: temporary */
+	const char __user *buf = iov[0].iov_base;
+	size_t count = iov[0].iov_len;
 
 	dfprintk(VFS, "nfs: direct write(%s/%s, %lu@%Ld)\n",
-		file->f_dentry->d_parent->d_name.name,
-		file->f_dentry->d_name.name,
+		file->f_path.dentry->d_parent->d_name.name,
+		file->f_path.dentry->d_name.name,
 		(unsigned long) count, (long long) pos);
 
-	retval = -EINVAL;
-	if (!is_sync_kiocb(iocb))
-		goto out;
+	if (nr_segs != 1)
+		return -EINVAL;
 
 	retval = generic_write_checks(file, &pos, &count, 0);
 	if (retval)
@@ -757,19 +815,17 @@ nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t count,
 	retval = 0;
 	if (!count)
 		goto out;
-	iov.iov_len = count,
 
 	retval = -EFAULT;
-	if (!access_ok(VERIFY_READ, iov.iov_base, iov.iov_len))
+	if (!access_ok(VERIFY_READ, buf, count))
 		goto out;
 
 	retval = nfs_sync_mapping(mapping);
 	if (retval)
 		goto out;
 
-	retval = nfs_direct_write(inode, ctx, &iov, pos, 1);
-	if (mapping->nrpages)
-		invalidate_inode_pages2(mapping);
+	retval = nfs_direct_write(iocb, (unsigned long) buf, count, pos);
+
 	if (retval > 0)
 		iocb->ki_pos = pos + retval;
 
@@ -777,11 +833,16 @@ out:
 	return retval;
 }
 
-int nfs_init_directcache(void)
+/**
+ * nfs_init_directcache - create a slab cache for nfs_direct_req structures
+ *
+ */
+int __init nfs_init_directcache(void)
 {
 	nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
 						sizeof(struct nfs_direct_req),
-						0, SLAB_RECLAIM_ACCOUNT,
+						0, (SLAB_RECLAIM_ACCOUNT|
+							SLAB_MEM_SPREAD),
 						NULL, NULL);
 	if (nfs_direct_cachep == NULL)
 		return -ENOMEM;
@@ -789,8 +850,11 @@ int nfs_init_directcache(void)
 	return 0;
 }
 
+/**
+ * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
+ *
+ */
 void nfs_destroy_directcache(void)
 {
-	if (kmem_cache_destroy(nfs_direct_cachep))
-		printk(KERN_INFO "nfs_direct_cache: not all structures were freed\n");
+	kmem_cache_destroy(nfs_direct_cachep);
 }