]> nv-tegra.nvidia Code Review - linux-2.6.git/blobdiff - fs/nfs/direct.c
NFS: Ensure that the read code cleans up properly when rpc_run_task() fails
[linux-2.6.git] / fs / nfs / direct.c
index 10ae377e68ff2e0e3253a51ef411c040a3a89f7d..9d9085b93a322249a3c823453129fb8a016f46aa 100644 (file)
@@ -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
  * 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>
-#include <linux/smp_lock.h>
 #include <linux/file.h>
 #include <linux/pagemap.h>
 #include <linux/kref.h>
 #include <asm/uaccess.h>
 #include <asm/atomic.h>
 
+#include "internal.h"
+#include "iostat.h"
+
 #define NFSDBG_FACILITY                NFSDBG_VFS
-#define MAX_DIRECTIO_SIZE      (4096UL << PAGE_SHIFT)
 
-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)
-{
-       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;
+static inline void get_dreq(struct nfs_direct_req *dreq)
+{
+       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);
-       }
-       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, unsigned int pgbase, size_t count)
 {
-       int i;
+       unsigned int npages;
+       unsigned int i;
+
+       if (count == 0)
+               return;
+       pages += (pgbase >> PAGE_SHIFT);
+       npages = (count + (pgbase & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
        for (i = 0; i < npages; i++) {
                struct page *page = pages[i];
-               if (do_dirty && !PageCompound(page))
-                       set_page_dirty_lock(page);
-               page_cache_release(page);
+               if (!PageCompound(page))
+                       set_page_dirty(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, unsigned int npages)
 {
-       struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
-       kmem_cache_free(nfs_direct_cachep, dreq);
+       unsigned 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_free(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);
+}
+
+static void nfs_direct_req_release(struct nfs_direct_req *dreq)
+{
+       kref_put(&dreq->kref, nfs_direct_req_free);
+}
+
+/*
+ * 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_killable(&dreq->completion);
+
+       if (!result)
+               result = dreq->error;
+       if (!result)
+               result = dreq->count;
+
+out:
+       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);
+
+       nfs_direct_req_release(dreq);
 }
 
-/**
- * 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_direct_req *dreq = (struct nfs_direct_req *) data->req;
+       struct nfs_read_data *data = calldata;
 
-       if (likely(status >= 0))
-               atomic_add(data->res.count, &dreq->count);
-       else
-               atomic_set(&dreq->error, status);
+       nfs_readpage_result(task, data);
+}
+
+static void nfs_direct_read_release(void *calldata)
+{
 
-       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);
+       struct nfs_read_data *data = calldata;
+       struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
+       int status = data->task.tk_status;
+
+       spin_lock(&dreq->lock);
+       if (unlikely(status < 0)) {
+               dreq->error = status;
+               spin_unlock(&dreq->lock);
+       } else {
+               dreq->count += data->res.count;
+               spin_unlock(&dreq->lock);
+               nfs_direct_dirty_pages(data->pagevec,
+                               data->args.pgbase,
+                               data->res.count);
        }
+       nfs_direct_release_pages(data->pagevec, data->npages);
+
+       if (put_dreq(dreq))
+               nfs_direct_complete(dreq);
+       nfs_readdata_release(calldata);
 }
 
-/**
- * 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_direct_read_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_segment(struct nfs_direct_req *dreq,
+                                               const struct iovec *iov,
+                                               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->path.dentry->d_inode;
+       unsigned long user_addr = (unsigned long)iov->iov_base;
+       size_t count = iov->iov_len;
+       size_t rsize = NFS_SERVER(inode)->rsize;
+       struct rpc_task *task;
+       struct rpc_message msg = {
+               .rpc_cred = ctx->cred,
+       };
+       struct rpc_task_setup task_setup_data = {
+               .rpc_client = NFS_CLIENT(inode),
+               .rpc_message = &msg,
+               .callback_ops = &nfs_read_direct_ops,
+               .workqueue = nfsiod_workqueue,
+               .flags = RPC_TASK_ASYNC,
+       };
+       unsigned int pgbase;
+       int result;
+       ssize_t started = 0;
 
-       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(nfs_page_array_len(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 (result < 0) {
+                       nfs_readdata_release(data);
+                       break;
+               }
+               if ((unsigned)result < data->npages) {
+                       bytes = result * PAGE_SIZE;
+                       if (bytes <= pgbase) {
+                               nfs_direct_release_pages(data->pagevec, result);
+                               nfs_readdata_release(data);
+                               break;
+                       }
+                       bytes -= pgbase;
+                       data->npages = result;
+               }
+
+               get_dreq(dreq);
+
+               data->req = (struct nfs_page *) dreq;
                data->inode = inode;
-               data->cred = ctx->cred;
+               data->cred = msg.rpc_cred;
                data->args.fh = NFS_FH(inode);
-               data->args.context = ctx;
-               data->args.offset = file_offset;
+               data->args.context = get_nfs_open_context(ctx);
+               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;
+               msg.rpc_argp = &data->args;
+               msg.rpc_resp = &data->res;
 
-               NFS_PROTO(inode)->read_setup(data);
-
-               data->task.tk_cookie = (unsigned long) inode;
-               data->complete = nfs_direct_read_result;
+               task_setup_data.task = &data->task;
+               task_setup_data.callback_data = data;
+               NFS_PROTO(inode)->read_setup(data, &msg);
 
-               lock_kernel();
-               rpc_execute(&data->task);
-               unlock_kernel();
+               task = rpc_run_task(&task_setup_data);
+               if (!IS_ERR(task))
+                       rpc_put_task(task);
 
-               dfprintk(VFS, "NFS: %4d initiated direct read call (req %s/%Ld, %u bytes @ offset %Lu)\n",
+               dprintk("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);
+
+       if (started)
+               return started;
+       return result < 0 ? (ssize_t) result : -EFAULT;
 }
 
-/**
- * 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)
+static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
+                                             const struct iovec *iov,
+                                             unsigned long nr_segs,
+                                             loff_t pos)
 {
-       int result = 0;
+       ssize_t result = -EINVAL;
+       size_t requested_bytes = 0;
+       unsigned long seg;
 
-       if (intr) {
-               result = wait_event_interruptible(dreq->wait,
-                                       (atomic_read(&dreq->complete) == 0));
-       } else {
-               wait_event(dreq->wait, (atomic_read(&dreq->complete) == 0));
+       get_dreq(dreq);
+
+       for (seg = 0; seg < nr_segs; seg++) {
+               const struct iovec *vec = &iov[seg];
+               result = nfs_direct_read_schedule_segment(dreq, vec, pos);
+               if (result < 0)
+                       break;
+               requested_bytes += result;
+               if ((size_t)result < vec->iov_len)
+                       break;
+               pos += vec->iov_len;
        }
 
-       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 (requested_bytes != 0)
+               return 0;
+
+       if (result < 0)
+               return result;
+       return -EIO;
 }
 
-/**
- * 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)
-{
-       ssize_t result;
-       sigset_t oldset;
-       struct rpc_clnt *clnt = NFS_CLIENT(inode);
+static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
+                              unsigned long nr_segs, loff_t pos)
+{
+       ssize_t result = 0;
+       struct inode *inode = iocb->ki_filp->f_mapping->host;
        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(nfs_file_open_context(iocb->ki_filp));
+       if (!is_sync_kiocb(iocb))
+               dreq->iocb = iocb;
 
-       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);
-       rpc_clnt_sigunmask(clnt, &oldset);
+       result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
+       if (!result)
+               result = nfs_direct_wait(dreq);
+       nfs_direct_req_release(dreq);
 
        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)
-{
-       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;
-                }
+static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
+{
+       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);
+       }
+}
+
+#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;
+       struct rpc_task *task;
+       struct rpc_message msg = {
+               .rpc_cred = dreq->ctx->cred,
+       };
+       struct rpc_task_setup task_setup_data = {
+               .rpc_client = NFS_CLIENT(inode),
+               .callback_ops = &nfs_write_direct_ops,
+               .workqueue = nfsiod_workqueue,
+               .flags = RPC_TASK_ASYNC,
+       };
+
+       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);
+
+               /* Use stable writes */
+               data->args.stable = NFS_FILE_SYNC;
+
+               /*
+                * 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.
+                */
+               task_setup_data.task = &data->task;
+               task_setup_data.callback_data = data;
+               msg.rpc_argp = &data->args;
+               msg.rpc_resp = &data->res;
+               NFS_PROTO(inode)->write_setup(data, &msg);
+
+               /*
+                * We're called via an RPC callback, so BKL is already held.
+                */
+               task = rpc_run_task(&task_setup_data);
+               if (!IS_ERR(task))
+                       rpc_put_task(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);
+       }
+
+       if (put_dreq(dreq))
+               nfs_direct_write_complete(dreq, inode);
+}
 
-               result = nfs_direct_read_seg(inode, ctx, user_addr, size,
-                               file_offset, pages, page_count);
+static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
+{
+       struct nfs_write_data *data = calldata;
+       struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
+
+       /* Call the NFS version-specific code */
+       if (NFS_PROTO(data->inode)->commit_done(task, data) != 0)
+               return;
+       if (unlikely(task->tk_status < 0)) {
+               dprintk("NFS: %5u commit failed with error %d.\n",
+                               task->tk_pid, task->tk_status);
+               dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
+       } else 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;
+       }
+
+       dprintk("NFS: %5u commit returned %d\n", task->tk_pid, task->tk_status);
+       nfs_direct_write_complete(dreq, data->inode);
+}
+
+static const struct rpc_call_ops nfs_commit_direct_ops = {
+       .rpc_call_done = nfs_direct_commit_result,
+       .rpc_release = nfs_commit_release,
+};
+
+static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
+{
+       struct nfs_write_data *data = dreq->commit_data;
+       struct rpc_task *task;
+       struct rpc_message msg = {
+               .rpc_argp = &data->args,
+               .rpc_resp = &data->res,
+               .rpc_cred = dreq->ctx->cred,
+       };
+       struct rpc_task_setup task_setup_data = {
+               .task = &data->task,
+               .rpc_client = NFS_CLIENT(dreq->inode),
+               .rpc_message = &msg,
+               .callback_ops = &nfs_commit_direct_ops,
+               .callback_data = data,
+               .workqueue = nfsiod_workqueue,
+               .flags = RPC_TASK_ASYNC,
+       };
+
+       data->inode = dreq->inode;
+       data->cred = msg.rpc_cred;
+
+       data->args.fh = NFS_FH(data->inode);
+       data->args.offset = 0;
+       data->args.count = 0;
+       data->args.context = get_nfs_open_context(dreq->ctx);
+       data->res.count = 0;
+       data->res.fattr = &data->fattr;
+       data->res.verf = &data->verf;
+
+       NFS_PROTO(data->inode)->commit_setup(data, &msg);
+
+       /* 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);
+
+       task = rpc_run_task(&task_setup_data);
+       if (!IS_ERR(task))
+               rpc_put_task(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:
+                       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);
+       }
+}
+
+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;
+}
 
-               if (result <= 0) {
-                       if (tot_bytes > 0)
+static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
+{
+       nfs_direct_free_writedata(dreq);
+       nfs_zap_mapping(inode, inode->i_mapping);
+       nfs_direct_complete(dreq);
+}
+#endif
+
+static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
+{
+       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)) {
+               /* An error has occurred, so we should not commit */
+               dreq->flags = 0;
+               dreq->error = status;
+       }
+       if (unlikely(dreq->error != 0))
+               goto out_unlock;
+
+       dreq->count += data->res.count;
+
+       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;
        }
+out_unlock:
+       spin_unlock(&dreq->lock);
+}
+
+/*
+ * NB: Return the value of the first error return code.  Subsequent
+ *     errors after the first one are ignored.
+ */
+static void nfs_direct_write_release(void *calldata)
+{
+       struct nfs_write_data *data = calldata;
+       struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
 
-       return tot_bytes;
+       if (put_dreq(dreq))
+               nfs_direct_write_complete(dreq, data->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 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_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)
-{
-       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;
+static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
+                                                const struct iovec *iov,
+                                                loff_t pos, int sync)
+{
+       struct nfs_open_context *ctx = dreq->ctx;
+       struct inode *inode = ctx->path.dentry->d_inode;
+       unsigned long user_addr = (unsigned long)iov->iov_base;
+       size_t count = iov->iov_len;
+       struct rpc_task *task;
+       struct rpc_message msg = {
+               .rpc_cred = ctx->cred,
+       };
+       struct rpc_task_setup task_setup_data = {
+               .rpc_client = NFS_CLIENT(inode),
+               .rpc_message = &msg,
+               .callback_ops = &nfs_write_direct_ops,
+               .workqueue = nfsiod_workqueue,
+               .flags = RPC_TASK_ASYNC,
+       };
+       size_t wsize = NFS_SERVER(inode)->wsize;
+       unsigned int pgbase;
+       int result;
+       ssize_t started = 0;
 
-       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;
-
-       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];
+               struct nfs_write_data *data;
+               size_t bytes;
 
-               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);
+               pgbase = user_addr & ~PAGE_MASK;
+               bytes = min(wsize,count);
 
-               lock_kernel();
-               result = NFS_PROTO(inode)->write(wdata);
-               unlock_kernel();
+               result = -ENOMEM;
+               data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
+               if (unlikely(!data))
+                       break;
 
-               if (result <= 0) {
-                       if (tot_bytes > 0)
+               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 (result < 0) {
+                       nfs_writedata_release(data);
+                       break;
+               }
+               if ((unsigned)result < data->npages) {
+                       bytes = result * PAGE_SIZE;
+                       if (bytes <= pgbase) {
+                               nfs_direct_release_pages(data->pagevec, result);
+                               nfs_writedata_release(data);
                                break;
-                       goto out;
+                       }
+                       bytes -= pgbase;
+                       data->npages = result;
                }
 
-               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;
-               }
+               get_dreq(dreq);
 
-               tot_bytes += result;
+               list_move_tail(&data->pages, &dreq->rewrite_list);
 
-               /* in case of a short write: stop now, let the app recover */
-               if (result < wdata->args.count)
-                       break;
+               data->req = (struct nfs_page *) dreq;
+               data->inode = inode;
+               data->cred = msg.rpc_cred;
+               data->args.fh = NFS_FH(inode);
+               data->args.context = get_nfs_open_context(ctx);
+               data->args.offset = pos;
+               data->args.pgbase = pgbase;
+               data->args.pages = data->pagevec;
+               data->args.count = bytes;
+               data->args.stable = sync;
+               data->res.fattr = &data->fattr;
+               data->res.count = bytes;
+               data->res.verf = &data->verf;
 
-               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;
-       }
-       result = tot_bytes;
+               task_setup_data.task = &data->task;
+               task_setup_data.callback_data = data;
+               msg.rpc_argp = &data->args;
+               msg.rpc_resp = &data->res;
+               NFS_PROTO(inode)->write_setup(data, &msg);
 
-out:
-       nfs_end_data_update(inode);
-       nfs_writedata_free(wdata);
-       return result;
+               task = rpc_run_task(&task_setup_data);
+               if (!IS_ERR(task))
+                       rpc_put_task(task);
+
+               dprintk("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);
 
-sync_retry:
-       wdata->args.stable = NFS_FILE_SYNC;
-       goto retry;
+       if (started)
+               return started;
+       return result < 0 ? (ssize_t) result : -EFAULT;
 }
 
-/**
- * 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)
-{
-       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;
-                }
+static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
+                                              const struct iovec *iov,
+                                              unsigned long nr_segs,
+                                              loff_t pos, int sync)
+{
+       ssize_t result = 0;
+       size_t requested_bytes = 0;
+       unsigned long seg;
 
-               result = nfs_direct_write_seg(inode, ctx, user_addr, size,
-                               file_offset, pages, page_count);
-               nfs_free_user_pages(pages, page_count, 0);
+       get_dreq(dreq);
 
-               if (result <= 0) {
-                       if (tot_bytes > 0)
-                               break;
-                       return result;
-               }
-               tot_bytes += result;
-               file_offset += result;
-               if (result < size)
+       for (seg = 0; seg < nr_segs; seg++) {
+               const struct iovec *vec = &iov[seg];
+               result = nfs_direct_write_schedule_segment(dreq, vec,
+                                                          pos, sync);
+               if (result < 0)
+                       break;
+               requested_bytes += result;
+               if ((size_t)result < vec->iov_len)
                        break;
+               pos += vec->iov_len;
        }
-       return tot_bytes;
+
+       if (put_dreq(dreq))
+               nfs_direct_write_complete(dreq, dreq->inode);
+
+       if (requested_bytes != 0)
+               return 0;
+
+       if (result < 0)
+               return result;
+       return -EIO;
 }
 
-/**
- * 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
- *
- */
-ssize_t
-nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
-               loff_t file_offset, unsigned long nr_segs)
+static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
+                               unsigned long nr_segs, loff_t pos,
+                               size_t count)
 {
-       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;
+       ssize_t result = 0;
+       struct inode *inode = iocb->ki_filp->f_mapping->host;
+       struct nfs_direct_req *dreq;
+       size_t wsize = NFS_SERVER(inode)->wsize;
+       int sync = NFS_UNSTABLE;
+
+       dreq = nfs_direct_req_alloc();
+       if (!dreq)
+               return -ENOMEM;
+       nfs_alloc_commit_data(dreq);
+
+       if (dreq->commit_data == NULL || count < wsize)
+               sync = NFS_FILE_SYNC;
 
-       /*
-        * No support for async yet
-        */
+       dreq->inode = inode;
+       dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
        if (!is_sync_kiocb(iocb))
-               return result;
+               dreq->iocb = iocb;
+
+       result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
+       if (!result)
+               result = nfs_direct_wait(dreq);
+       nfs_direct_req_release(dreq);
 
-       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;
-       }
        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,
-       };
+       size_t count;
 
-       dprintk("nfs: direct read(%s/%s, %lu@%Ld)\n",
-               file->f_dentry->d_parent->d_name.name,
-               file->f_dentry->d_name.name,
-               (unsigned long) count, (long long) pos);
+       count = iov_length(iov, nr_segs);
+       nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
+
+       dprintk("nfs: direct read(%s/%s, %zd@%Ld)\n",
+               file->f_path.dentry->d_parent->d_name.name,
+               file->f_path.dentry->d_name.name,
+               count, (long long) pos);
 
-       if (!is_sync_kiocb(iocb))
-               goto out;
-       if (count < 0)
-               goto out;
-       retval = -EFAULT;
-       if (!access_ok(VERIFY_WRITE, iov.iov_base, iov.iov_len))
-               goto out;
        retval = 0;
        if (!count)
                goto out;
@@ -682,9 +895,9 @@ 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, iov, nr_segs, pos);
        if (retval > 0)
-               *ppos = pos + retval;
+               iocb->ki_pos = pos + retval;
 
 out:
        return retval;
@@ -693,9 +906,9 @@ 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
@@ -715,27 +928,21 @@ 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;
+       ssize_t retval = -EINVAL;
        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,
-       };
+       size_t count;
 
-       dfprintk(VFS, "nfs: direct write(%s/%s, %lu@%Ld)\n",
-               file->f_dentry->d_parent->d_name.name,
-               file->f_dentry->d_name.name,
-               (unsigned long) count, (long long) pos);
+       count = iov_length(iov, nr_segs);
+       nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
 
-       retval = -EINVAL;
-       if (!is_sync_kiocb(iocb))
-               goto out;
+       dfprintk(VFS, "nfs: direct write(%s/%s, %zd@%Ld)\n",
+               file->f_path.dentry->d_parent->d_name.name,
+               file->f_path.dentry->d_name.name,
+               count, (long long) pos);
 
        retval = generic_write_checks(file, &pos, &count, 0);
        if (retval)
@@ -747,19 +954,13 @@ 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))
-               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, iov, nr_segs, pos, count);
+
        if (retval > 0)
                iocb->ki_pos = pos + retval;
 
@@ -767,20 +968,28 @@ 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,
-                                               NULL, NULL);
+                                               0, (SLAB_RECLAIM_ACCOUNT|
+                                                       SLAB_MEM_SPREAD),
+                                               NULL);
        if (nfs_direct_cachep == NULL)
                return -ENOMEM;
 
        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);
 }