X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=fs%2Fnfs%2Fdirect.c;h=b1630d53fbb1fa4484ddd16c160c4cdadb210631;hb=06cf6f2ed0b19629700794727d86ed57b9c0583e;hp=3c72b0c072839383950c59955da28c6c098897bf;hpb=55308c3712f56279d5547ef6e97d365ac3ab9e6d;p=linux-2.6

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 3c72b0c072..b1630d53fb 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -73,15 +73,10 @@ struct nfs_direct_req {
 	struct nfs_open_context	*ctx;		/* file open context info */
 	struct kiocb *		iocb;		/* controlling i/o request */
 	struct inode *		inode;		/* target file of i/o */
-	unsigned long		user_addr;	/* location of user's buffer */
-	size_t			user_count;	/* total bytes to move */
-	loff_t			pos;		/* starting offset in file */
-	struct page **		pages;		/* pages in our buffer */
-	unsigned int		npages;		/* count of pages */
 
 	/* completion state */
+	atomic_t		io_count;	/* i/os we're waiting for */
 	spinlock_t		lock;		/* protect completion state */
-	int			outstanding;	/* i/os we're waiting for */
 	ssize_t			count,		/* bytes actually processed */
 				error;		/* any reported error */
 	struct completion	completion;	/* wait for i/o completion */
@@ -94,8 +89,32 @@ struct nfs_direct_req {
 	struct nfs_writeverf	verf;		/* unstable write verifier */
 };
 
-static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, int sync);
 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
+static const struct rpc_call_ops nfs_write_direct_ops;
+
+static inline void get_dreq(struct nfs_direct_req *dreq)
+{
+	atomic_inc(&dreq->io_count);
+}
+
+static inline int put_dreq(struct nfs_direct_req *dreq)
+{
+	return atomic_dec_and_test(&dreq->io_count);
+}
+
+/*
+ * "size" is never larger than rsize or wsize.
+ */
+static inline int nfs_direct_count_pages(unsigned long user_addr, size_t size)
+{
+	int page_count;
+
+	page_count = (user_addr + size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	page_count -= user_addr >> PAGE_SHIFT;
+	BUG_ON(page_count < 0);
+
+	return page_count;
+}
 
 /**
  * nfs_direct_IO - NFS address space operation for direct I/O
@@ -119,50 +138,21 @@ ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_
 	return -EINVAL;
 }
 
-static void nfs_free_user_pages(struct page **pages, int npages, int do_dirty)
+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);
 }
 
-static inline int nfs_get_user_pages(int rw, unsigned long user_addr, size_t size, struct page ***pages)
+static void nfs_direct_release_pages(struct page **pages, int npages)
 {
-	int result = -ENOMEM;
-	unsigned long page_count;
-	size_t array_size;
-
-	page_count = (user_addr + size + PAGE_SIZE - 1) >> PAGE_SHIFT;
-	page_count -= user_addr >> PAGE_SHIFT;
-
-	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 (result != page_count) {
-			/*
-			 * 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) {
-				nfs_free_user_pages(*pages, result, 0);
-				result = -EFAULT;
-			} else
-				kfree(*pages);
-			*pages = NULL;
-		}
-	}
-	return result;
+	int i;
+	for (i = 0; i < npages; i++)
+		page_cache_release(pages[i]);
 }
 
 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
@@ -180,7 +170,7 @@ static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
 	dreq->iocb = NULL;
 	dreq->ctx = NULL;
 	spin_lock_init(&dreq->lock);
-	dreq->outstanding = 0;
+	atomic_set(&dreq->io_count, 0);
 	dreq->count = 0;
 	dreq->error = 0;
 	dreq->flags = 0;
@@ -221,18 +211,11 @@ out:
 }
 
 /*
- * 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_wait (for instance, if someone hits ^C on a slow server).
- *
- * In addition, 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.  If the waiter is woken prematurely, the iocb is long gone.
+ * 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)
 {
-	nfs_free_user_pages(dreq->pages, dreq->npages, 1);
-
 	if (dreq->iocb) {
 		long res = (long) dreq->error;
 		if (!res)
@@ -278,7 +261,7 @@ static struct nfs_direct_req *nfs_direct_read_alloc(size_t nbytes, size_t rsize)
 		list_add(&data->pages, list);
 
 		data->req = (struct nfs_page *) dreq;
-		dreq->outstanding++;
+		get_dreq(dreq);
 		if (nbytes <= rsize)
 			break;
 		nbytes -= rsize;
@@ -287,6 +270,11 @@ static struct nfs_direct_req *nfs_direct_read_alloc(size_t nbytes, size_t rsize)
 	return dreq;
 }
 
+/*
+ * 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_wait (for instance, if someone hits ^C on a slow server).
+ */
 static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
 {
 	struct nfs_read_data *data = calldata;
@@ -295,6 +283,9 @@ static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
 	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))
@@ -302,13 +293,10 @@ static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
 	else
 		dreq->error = task->tk_status;
 
-	if (--dreq->outstanding) {
-		spin_unlock(&dreq->lock);
-		return;
-	}
-
 	spin_unlock(&dreq->lock);
-	nfs_direct_complete(dreq);
+
+	if (put_dreq(dreq))
+		nfs_direct_complete(dreq);
 }
 
 static const struct rpc_call_ops nfs_read_direct_ops = {
@@ -318,23 +306,23 @@ static const struct rpc_call_ops nfs_read_direct_ops = {
 
 /*
  * For each nfs_read_data struct that was allocated on the list, dispatch
- * an NFS READ operation
+ * an NFS READ operation.  If get_user_pages() fails, we stop sending reads.
+ * Read length accounting is handled 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)
+static ssize_t nfs_direct_read_schedule(struct nfs_direct_req *dreq, unsigned long user_addr, size_t count, loff_t pos)
 {
 	struct nfs_open_context *ctx = dreq->ctx;
 	struct inode *inode = ctx->dentry->d_inode;
 	struct list_head *list = &dreq->list;
-	struct page **pages = dreq->pages;
-	size_t count = dreq->user_count;
-	loff_t pos = dreq->pos;
 	size_t rsize = NFS_SERVER(inode)->rsize;
-	unsigned int curpage, pgbase;
+	unsigned int pgbase;
+	int result;
+	ssize_t started = 0;
+	struct nfs_read_data *data;
 
-	curpage = 0;
-	pgbase = dreq->user_addr & ~PAGE_MASK;
+	pgbase = user_addr & ~PAGE_MASK;
 	do {
-		struct nfs_read_data *data;
 		size_t bytes;
 
 		bytes = rsize;
@@ -345,13 +333,21 @@ static void nfs_direct_read_schedule(struct nfs_direct_req *dreq)
 		data = list_entry(list->next, struct nfs_read_data, pages);
 		list_del_init(&data->pages);
 
+		data->npages = nfs_direct_count_pages(user_addr, bytes);
+		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))
+			goto out_err;
+
 		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 = &pages[curpage];
+		data->args.pages = data->pagevec;
 		data->args.count = bytes;
 		data->res.fattr = &data->fattr;
 		data->res.eof = 0;
@@ -374,17 +370,36 @@ static void nfs_direct_read_schedule(struct nfs_direct_req *dreq)
 				bytes,
 				(unsigned long long)data->args.offset);
 
+		started += bytes;
+		user_addr += bytes;
 		pos += bytes;
 		pgbase += bytes;
-		curpage += pgbase >> PAGE_SHIFT;
 		pgbase &= ~PAGE_MASK;
 
 		count -= bytes;
 	} while (count != 0);
 	BUG_ON(!list_empty(list));
+	return 0;
+
+out_err:
+	if (result > 0)
+		nfs_direct_release_pages(data->pagevec, result);
+
+	list_add(&data->pages, list);
+	while (!list_empty(list)) {
+		data = list_entry(list->next, struct nfs_read_data, pages);
+		list_del(&data->pages);
+		nfs_readdata_free(data);
+		if (put_dreq(dreq))
+			nfs_direct_complete(dreq);
+	}
+
+	if (started)
+		return 0;
+	return result < 0 ? (ssize_t) result : -EFAULT;
 }
 
-static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos, 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;
 	sigset_t oldset;
@@ -396,11 +411,6 @@ static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size
 	if (!dreq)
 		return -ENOMEM;
 
-	dreq->user_addr = user_addr;
-	dreq->user_count = count;
-	dreq->pos = pos;
-	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))
@@ -408,8 +418,9 @@ static ssize_t nfs_direct_read(struct kiocb *iocb, unsigned long user_addr, size
 
 	nfs_add_stats(inode, NFSIOS_DIRECTREADBYTES, count);
 	rpc_clnt_sigmask(clnt, &oldset);
-	nfs_direct_read_schedule(dreq);
-	result = nfs_direct_wait(dreq);
+	result = nfs_direct_read_schedule(dreq, user_addr, count, pos);
+	if (!result)
+		result = nfs_direct_wait(dreq);
 	rpc_clnt_sigunmask(clnt, &oldset);
 
 	return result;
@@ -421,6 +432,7 @@ static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
 	while (!list_empty(&dreq->list)) {
 		struct nfs_write_data *data = list_entry(dreq->list.next, struct nfs_write_data, pages);
 		list_del(&data->pages);
+		nfs_direct_release_pages(data->pagevec, data->npages);
 		nfs_writedata_release(data);
 	}
 }
@@ -428,14 +440,51 @@ static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 {
-	struct list_head *pos;
+	struct inode *inode = dreq->inode;
+	struct list_head *p;
+	struct nfs_write_data *data;
 
-	list_splice_init(&dreq->rewrite_list, &dreq->list);
-	list_for_each(pos, &dreq->list)
-		dreq->outstanding++;
 	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);
 
-	nfs_direct_write_schedule(dreq, 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);
+	}
+
+	if (put_dreq(dreq))
+		nfs_direct_write_complete(dreq, inode);
 }
 
 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
@@ -472,8 +521,8 @@ static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
 	data->cred = dreq->ctx->cred;
 
 	data->args.fh = NFS_FH(data->inode);
-	data->args.offset = dreq->pos;
-	data->args.count = dreq->user_count;
+	data->args.offset = 0;
+	data->args.count = 0;
 	data->res.count = 0;
 	data->res.fattr = &data->fattr;
 	data->res.verf = &data->verf;
@@ -564,7 +613,7 @@ static struct nfs_direct_req *nfs_direct_write_alloc(size_t nbytes, size_t wsize
 		list_add(&data->pages, list);
 
 		data->req = (struct nfs_page *) dreq;
-		dreq->outstanding++;
+		get_dreq(dreq);
 		if (nbytes <= wsize)
 			break;
 		nbytes -= wsize;
@@ -605,8 +654,6 @@ static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
 				}
 		}
 	}
-	/* In case we have to resend */
-	data->args.stable = NFS_FILE_SYNC;
 
 	spin_unlock(&dreq->lock);
 }
@@ -620,14 +667,8 @@ 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;
 
-	spin_lock(&dreq->lock);
-	if (--dreq->outstanding) {
-		spin_unlock(&dreq->lock);
-		return;
-	}
-	spin_unlock(&dreq->lock);
-
-	nfs_direct_write_complete(dreq, data->inode);
+	if (put_dreq(dreq))
+		nfs_direct_write_complete(dreq, data->inode);
 }
 
 static const struct rpc_call_ops nfs_write_direct_ops = {
@@ -637,23 +678,23 @@ static const struct rpc_call_ops nfs_write_direct_ops = {
 
 /*
  * For each nfs_write_data struct that was allocated on the list, dispatch
- * an NFS WRITE operation
+ * an NFS WRITE operation.  If get_user_pages() fails, we stop sending writes.
+ * Write length accounting is handled by nfs_direct_write_result().
+ * Otherwise, if no requests have been sent, just return an error.
  */
-static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, int sync)
+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;
 	struct list_head *list = &dreq->list;
-	struct page **pages = dreq->pages;
-	size_t count = dreq->user_count;
-	loff_t pos = dreq->pos;
 	size_t wsize = NFS_SERVER(inode)->wsize;
-	unsigned int curpage, pgbase;
+	unsigned int pgbase;
+	int result;
+	ssize_t started = 0;
+	struct nfs_write_data *data;
 
-	curpage = 0;
-	pgbase = dreq->user_addr & ~PAGE_MASK;
+	pgbase = user_addr & ~PAGE_MASK;
 	do {
-		struct nfs_write_data *data;
 		size_t bytes;
 
 		bytes = wsize;
@@ -662,6 +703,15 @@ static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, int sync)
 
 		BUG_ON(list_empty(list));
 		data = list_entry(list->next, struct nfs_write_data, pages);
+
+		data->npages = nfs_direct_count_pages(user_addr, bytes);
+		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))
+			goto out_err;
+
 		list_move_tail(&data->pages, &dreq->rewrite_list);
 
 		data->inode = inode;
@@ -670,7 +720,7 @@ static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, int sync)
 		data->args.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.count = bytes;
@@ -694,17 +744,36 @@ static void nfs_direct_write_schedule(struct nfs_direct_req *dreq, int sync)
 				bytes,
 				(unsigned long long)data->args.offset);
 
+		started += bytes;
+		user_addr += bytes;
 		pos += bytes;
 		pgbase += bytes;
-		curpage += pgbase >> PAGE_SHIFT;
 		pgbase &= ~PAGE_MASK;
 
 		count -= bytes;
 	} while (count != 0);
 	BUG_ON(!list_empty(list));
+	return 0;
+
+out_err:
+	if (result > 0)
+		nfs_direct_release_pages(data->pagevec, result);
+
+	list_add(&data->pages, list);
+	while (!list_empty(list)) {
+		data = list_entry(list->next, struct nfs_write_data, pages);
+		list_del(&data->pages);
+		nfs_writedata_free(data);
+		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, struct page **pages, int nr_pages)
+static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, size_t count, loff_t pos)
 {
 	ssize_t result;
 	sigset_t oldset;
@@ -720,11 +789,6 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, siz
 	if (dreq->commit_data == NULL || count < wsize)
 		sync = FLUSH_STABLE;
 
-	dreq->user_addr = user_addr;
-	dreq->user_count = count;
-	dreq->pos = pos;
-	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))
@@ -735,8 +799,9 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, siz
 	nfs_begin_data_update(inode);
 
 	rpc_clnt_sigmask(clnt, &oldset);
-	nfs_direct_write_schedule(dreq, sync);
-	result = nfs_direct_wait(dreq);
+	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;
@@ -766,8 +831,6 @@ static ssize_t nfs_direct_write(struct kiocb *iocb, unsigned long user_addr, siz
 ssize_t nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
 {
 	ssize_t retval = -EINVAL;
-	int page_count;
-	struct page **pages;
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
 
@@ -789,14 +852,7 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count,
 	if (retval)
 		goto out;
 
-	retval = nfs_get_user_pages(READ, (unsigned long) buf,
-						count, &pages);
-	if (retval < 0)
-		goto out;
-	page_count = retval;
-
-	retval = nfs_direct_read(iocb, (unsigned long) buf, count, pos,
-						pages, page_count);
+	retval = nfs_direct_read(iocb, (unsigned long) buf, count, pos);
 	if (retval > 0)
 		iocb->ki_pos = pos + retval;
 
@@ -832,8 +888,6 @@ out:
 ssize_t nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t count, loff_t pos)
 {
 	ssize_t retval;
-	int page_count;
-	struct page **pages;
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
 
@@ -861,14 +915,7 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t
 	if (retval)
 		goto out;
 
-	retval = nfs_get_user_pages(WRITE, (unsigned long) buf,
-						count, &pages);
-	if (retval < 0)
-		goto out;
-	page_count = retval;
-
-	retval = nfs_direct_write(iocb, (unsigned long) buf, count,
-					pos, pages, page_count);
+	retval = nfs_direct_write(iocb, (unsigned long) buf, count, pos);
 
 	/*
 	 * XXX: nfs_end_data_update() already ensures this file's
@@ -892,7 +939,7 @@ out:
  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
  *
  */
-int nfs_init_directcache(void)
+int __init nfs_init_directcache(void)
 {
 	nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
 						sizeof(struct nfs_direct_req),
@@ -906,10 +953,10 @@ int nfs_init_directcache(void)
 }
 
 /**
- * nfs_init_directcache - destroy the slab cache for nfs_direct_req structures
+ * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
  *
  */
-void nfs_destroy_directcache(void)
+void __exit nfs_destroy_directcache(void)
 {
 	if (kmem_cache_destroy(nfs_direct_cachep))
 		printk(KERN_INFO "nfs_direct_cache: not all structures were freed\n");