1 files changed, 309 insertions, 0 deletions
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
new file mode 100644
index 000000000000..4f1ba723848d
--- /dev/null
+++ b/fs/nfs/pagelist.c
@@ -0,0 +1,309 @@
+/*
+ * linux/fs/nfs/pagelist.c
+ *
+ * A set of helper functions for managing NFS read and write requests.
+ * The main purpose of these routines is to provide support for the
+ * coalescing of several requests into a single RPC call.
+ *
+ * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/nfs3.h>
+#include <linux/nfs4.h>
+#include <linux/nfs_page.h>
+#include <linux/nfs_fs.h>
+#include <linux/nfs_mount.h>
+
+#define NFS_PARANOIA 1
+
+static kmem_cache_t *nfs_page_cachep;
+
+static inline struct nfs_page *
+nfs_page_alloc(void)
+{
+	struct nfs_page	*p;
+	p = kmem_cache_alloc(nfs_page_cachep, SLAB_KERNEL);
+	if (p) {
+		memset(p, 0, sizeof(*p));
+		INIT_LIST_HEAD(&p->wb_list);
+	}
+	return p;
+}
+
+static inline void
+nfs_page_free(struct nfs_page *p)
+{
+	kmem_cache_free(nfs_page_cachep, p);
+}
+
+/**
+ * nfs_create_request - Create an NFS read/write request.
+ * @file: file descriptor to use
+ * @inode: inode to which the request is attached
+ * @page: page to write
+ * @offset: starting offset within the page for the write
+ * @count: number of bytes to read/write
+ *
+ * The page must be locked by the caller. This makes sure we never
+ * create two different requests for the same page, and avoids
+ * a possible deadlock when we reach the hard limit on the number
+ * of dirty pages.
+ * User should ensure it is safe to sleep in this function.
+ */
+struct nfs_page *
+nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
+		   struct page *page,
+		   unsigned int offset, unsigned int count)
+{
+	struct nfs_server *server = NFS_SERVER(inode);
+	struct nfs_page		*req;
+
+	/* Deal with hard limits.  */
+	for (;;) {
+		/* try to allocate the request struct */
+		req = nfs_page_alloc();
+		if (req != NULL)
+			break;
+
+		/* Try to free up at least one request in order to stay
+		 * below the hard limit
+		 */
+		if (signalled() && (server->flags & NFS_MOUNT_INTR))
+			return ERR_PTR(-ERESTARTSYS);
+		yield();
+	}
+
+	/* Initialize the request struct. Initially, we assume a
+	 * long write-back delay. This will be adjusted in
+	 * update_nfs_request below if the region is not locked. */
+	req->wb_page    = page;
+	atomic_set(&req->wb_complete, 0);
+	req->wb_index	= page->index;
+	page_cache_get(page);
+	req->wb_offset  = offset;
+	req->wb_pgbase	= offset;
+	req->wb_bytes   = count;
+	atomic_set(&req->wb_count, 1);
+	req->wb_context = get_nfs_open_context(ctx);
+
+	return req;
+}
+
+/**
+ * nfs_unlock_request - Unlock request and wake up sleepers.
+ * @req:
+ */
+void nfs_unlock_request(struct nfs_page *req)
+{
+	if (!NFS_WBACK_BUSY(req)) {
+		printk(KERN_ERR "NFS: Invalid unlock attempted\n");
+		BUG();
+	}
+	smp_mb__before_clear_bit();
+	clear_bit(PG_BUSY, &req->wb_flags);
+	smp_mb__after_clear_bit();
+	wake_up_all(&req->wb_context->waitq);
+	nfs_release_request(req);
+}
+
+/**
+ * nfs_clear_request - Free up all resources allocated to the request
+ * @req:
+ *
+ * Release page resources associated with a write request after it
+ * has completed.
+ */
+void nfs_clear_request(struct nfs_page *req)
+{
+	if (req->wb_page) {
+		page_cache_release(req->wb_page);
+		req->wb_page = NULL;
+	}
+}
+
+
+/**
+ * nfs_release_request - Release the count on an NFS read/write request
+ * @req: request to release
+ *
+ * Note: Should never be called with the spinlock held!
+ */
+void
+nfs_release_request(struct nfs_page *req)
+{
+	if (!atomic_dec_and_test(&req->wb_count))
+		return;
+
+#ifdef NFS_PARANOIA
+	BUG_ON (!list_empty(&req->wb_list));
+	BUG_ON (NFS_WBACK_BUSY(req));
+#endif
+
+	/* Release struct file or cached credential */
+	nfs_clear_request(req);
+	put_nfs_open_context(req->wb_context);
+	nfs_page_free(req);
+}
+
+/**
+ * nfs_list_add_request - Insert a request into a sorted list
+ * @req: request
+ * @head: head of list into which to insert the request.
+ *
+ * Note that the wb_list is sorted by page index in order to facilitate
+ * coalescing of requests.
+ * We use an insertion sort that is optimized for the case of appended
+ * writes.
+ */
+void
+nfs_list_add_request(struct nfs_page *req, struct list_head *head)
+{
+	struct list_head *pos;
+
+#ifdef NFS_PARANOIA
+	if (!list_empty(&req->wb_list)) {
+		printk(KERN_ERR "NFS: Add to list failed!\n");
+		BUG();
+	}
+#endif
+	list_for_each_prev(pos, head) {
+		struct nfs_page	*p = nfs_list_entry(pos);
+		if (p->wb_index < req->wb_index)
+			break;
+	}
+	list_add(&req->wb_list, pos);
+	req->wb_list_head = head;
+}
+
+/**
+ * nfs_wait_on_request - Wait for a request to complete.
+ * @req: request to wait upon.
+ *
+ * Interruptible by signals only if mounted with intr flag.
+ * The user is responsible for holding a count on the request.
+ */
+int
+nfs_wait_on_request(struct nfs_page *req)
+{
+	struct inode	*inode = req->wb_context->dentry->d_inode;
+        struct rpc_clnt	*clnt = NFS_CLIENT(inode);
+
+	if (!NFS_WBACK_BUSY(req))
+		return 0;
+	return nfs_wait_event(clnt, req->wb_context->waitq, !NFS_WBACK_BUSY(req));
+}
+
+/**
+ * nfs_coalesce_requests - Split coalesced requests out from a list.
+ * @head: source list
+ * @dst: destination list
+ * @nmax: maximum number of requests to coalesce
+ *
+ * Moves a maximum of 'nmax' elements from one list to another.
+ * The elements are checked to ensure that they form a contiguous set
+ * of pages, and that the RPC credentials are the same.
+ */
+int
+nfs_coalesce_requests(struct list_head *head, struct list_head *dst,
+		      unsigned int nmax)
+{
+	struct nfs_page		*req = NULL;
+	unsigned int		npages = 0;
+
+	while (!list_empty(head)) {
+		struct nfs_page	*prev = req;
+
+		req = nfs_list_entry(head->next);
+		if (prev) {
+			if (req->wb_context->cred != prev->wb_context->cred)
+				break;
+			if (req->wb_context->lockowner != prev->wb_context->lockowner)
+				break;
+			if (req->wb_context->state != prev->wb_context->state)
+				break;
+			if (req->wb_index != (prev->wb_index + 1))
+				break;
+
+			if (req->wb_pgbase != 0)
+				break;
+		}
+		nfs_list_remove_request(req);
+		nfs_list_add_request(req, dst);
+		npages++;
+		if (req->wb_pgbase + req->wb_bytes != PAGE_CACHE_SIZE)
+			break;
+		if (npages >= nmax)
+			break;
+	}
+	return npages;
+}
+
+/**
+ * nfs_scan_list - Scan a list for matching requests
+ * @head: One of the NFS inode request lists
+ * @dst: Destination list
+ * @idx_start: lower bound of page->index to scan
+ * @npages: idx_start + npages sets the upper bound to scan.
+ *
+ * Moves elements from one of the inode request lists.
+ * If the number of requests is set to 0, the entire address_space
+ * starting at index idx_start, is scanned.
+ * The requests are *not* checked to ensure that they form a contiguous set.
+ * You must be holding the inode's req_lock when calling this function
+ */
+int
+nfs_scan_list(struct list_head *head, struct list_head *dst,
+	      unsigned long idx_start, unsigned int npages)
+{
+	struct list_head	*pos, *tmp;
+	struct nfs_page		*req;
+	unsigned long		idx_end;
+	int			res;
+
+	res = 0;
+	if (npages == 0)
+		idx_end = ~0;
+	else
+		idx_end = idx_start + npages - 1;
+
+	list_for_each_safe(pos, tmp, head) {
+
+		req = nfs_list_entry(pos);
+
+		if (req->wb_index < idx_start)
+			continue;
+		if (req->wb_index > idx_end)
+			break;
+
+		if (!nfs_lock_request(req))
+			continue;
+		nfs_list_remove_request(req);
+		nfs_list_add_request(req, dst);
+		res++;
+	}
+	return res;
+}
+
+int nfs_init_nfspagecache(void)
+{
+	nfs_page_cachep = kmem_cache_create("nfs_page",
+					    sizeof(struct nfs_page),
+					    0, SLAB_HWCACHE_ALIGN,
+					    NULL, NULL);
+	if (nfs_page_cachep == NULL)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void nfs_destroy_nfspagecache(void)
+{
+	if (kmem_cache_destroy(nfs_page_cachep))
+		printk(KERN_INFO "nfs_page: not all structures were freed\n");
+}
+