1 files changed, 132 insertions, 110 deletions

diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index ca4b1d4ff42b..388950118f59 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -17,7 +17,8 @@
 #include <linux/nfs_page.h>
 #include <linux/nfs_fs.h>
 #include <linux/nfs_mount.h>
-#include <linux/writeback.h>
+
+#include "internal.h"
 
 #define NFS_PARANOIA 1
 
@@ -50,9 +51,7 @@ nfs_page_free(struct nfs_page *p)
  * @count: number of bytes to read/write
  *
  * The page must be locked by the caller. This makes sure we never
- * create two different requests for the same page, and avoids
- * a possible deadlock when we reach the hard limit on the number
- * of dirty pages.
+ * create two different requests for the same page.
  * User should ensure it is safe to sleep in this function.
  */
 struct nfs_page *
@@ -63,16 +62,12 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
 	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();
@@ -223,124 +218,151 @@ out:
 }
 
 /**
- * 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.
+ * nfs_pageio_init - initialise a page io descriptor
+ * @desc: pointer to descriptor
+ * @inode: pointer to inode
+ * @doio: pointer to io function
+ * @bsize: io block size
+ * @io_flags: extra parameters for the io function
  */
-int
-nfs_coalesce_requests(struct list_head *head, struct list_head *dst,
-		      unsigned int nmax)
+void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
+		     struct inode *inode,
+		     int (*doio)(struct inode *, struct list_head *, unsigned int, size_t, int),
+		     size_t bsize,
+		     int io_flags)
 {
-	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;
+	INIT_LIST_HEAD(&desc->pg_list);
+	desc->pg_bytes_written = 0;
+	desc->pg_count = 0;
+	desc->pg_bsize = bsize;
+	desc->pg_base = 0;
+	desc->pg_inode = inode;
+	desc->pg_doio = doio;
+	desc->pg_ioflags = io_flags;
+	desc->pg_error = 0;
 }
 
-#define NFS_SCAN_MAXENTRIES 16
 /**
- * nfs_scan_dirty - Scan the radix tree for dirty requests
- * @mapping: pointer to address space
- * @wbc: writeback_control structure
- * @dst: Destination list
+ * nfs_can_coalesce_requests - test two requests for compatibility
+ * @prev: pointer to nfs_page
+ * @req: pointer to nfs_page
  *
- * Moves elements from one of the inode request lists.
- * If the number of requests is set to 0, the entire address_space
- * starting at index idx_start, is scanned.
- * The requests are *not* checked to ensure that they form a contiguous set.
- * You must be holding the inode's req_lock when calling this function
+ * The nfs_page structures 'prev' and 'req' are compared to ensure that the
+ * page data area they describe is contiguous, and that their RPC
+ * credentials, NFSv4 open state, and lockowners are the same.
+ *
+ * Return 'true' if this is the case, else return 'false'.
  */
-long nfs_scan_dirty(struct address_space *mapping,
-			struct writeback_control *wbc,
-			struct list_head *dst)
+static int nfs_can_coalesce_requests(struct nfs_page *prev,
+				     struct nfs_page *req)
 {
-	struct nfs_inode *nfsi = NFS_I(mapping->host);
-	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
-	struct nfs_page *req;
-	pgoff_t idx_start, idx_end;
-	long res = 0;
-	int found, i;
-
-	if (nfsi->ndirty == 0)
+	if (req->wb_context->cred != prev->wb_context->cred)
 		return 0;
-	if (wbc->range_cyclic) {
-		idx_start = 0;
-		idx_end = ULONG_MAX;
-	} else if (wbc->range_end == 0) {
-		idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
-		idx_end = ULONG_MAX;
-	} else {
-		idx_start = wbc->range_start >> PAGE_CACHE_SHIFT;
-		idx_end = wbc->range_end >> PAGE_CACHE_SHIFT;
-	}
+	if (req->wb_context->lockowner != prev->wb_context->lockowner)
+		return 0;
+	if (req->wb_context->state != prev->wb_context->state)
+		return 0;
+	if (req->wb_index != (prev->wb_index + 1))
+		return 0;
+	if (req->wb_pgbase != 0)
+		return 0;
+	if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
+		return 0;
+	return 1;
+}
 
-	for (;;) {
-		unsigned int toscan = NFS_SCAN_MAXENTRIES;
+/**
+ * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
+ * @desc: destination io descriptor
+ * @req: request
+ *
+ * Returns true if the request 'req' was successfully coalesced into the
+ * existing list of pages 'desc'.
+ */
+static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
+				     struct nfs_page *req)
+{
+	size_t newlen = req->wb_bytes;
 
-		found = radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree,
-				(void **)&pgvec[0], idx_start, toscan,
-				NFS_PAGE_TAG_DIRTY);
+	if (desc->pg_count != 0) {
+		struct nfs_page *prev;
 
-		/* Did we make progress? */
-		if (found <= 0)
-			break;
+		/*
+		 * FIXME: ideally we should be able to coalesce all requests
+		 * that are not block boundary aligned, but currently this
+		 * is problematic for the case of bsize < PAGE_CACHE_SIZE,
+		 * since nfs_flush_multi and nfs_pagein_multi assume you
+		 * can have only one struct nfs_page.
+		 */
+		if (desc->pg_bsize < PAGE_SIZE)
+			return 0;
+		newlen += desc->pg_count;
+		if (newlen > desc->pg_bsize)
+			return 0;
+		prev = nfs_list_entry(desc->pg_list.prev);
+		if (!nfs_can_coalesce_requests(prev, req))
+			return 0;
+	} else
+		desc->pg_base = req->wb_pgbase;
+	nfs_list_remove_request(req);
+	nfs_list_add_request(req, &desc->pg_list);
+	desc->pg_count = newlen;
+	return 1;
+}
 
-		for (i = 0; i < found; i++) {
-			req = pgvec[i];
-			if (!wbc->range_cyclic && req->wb_index > idx_end)
-				goto out;
+/*
+ * Helper for nfs_pageio_add_request and nfs_pageio_complete
+ */
+static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
+{
+	if (!list_empty(&desc->pg_list)) {
+		int error = desc->pg_doio(desc->pg_inode,
+					  &desc->pg_list,
+					  nfs_page_array_len(desc->pg_base,
+							     desc->pg_count),
+					  desc->pg_count,
+					  desc->pg_ioflags);
+		if (error < 0)
+			desc->pg_error = error;
+		else
+			desc->pg_bytes_written += desc->pg_count;
+	}
+	if (list_empty(&desc->pg_list)) {
+		desc->pg_count = 0;
+		desc->pg_base = 0;
+	}
+}
 
-			/* Try to lock request and mark it for writeback */
-			if (!nfs_set_page_writeback_locked(req))
-				goto next;
-			radix_tree_tag_clear(&nfsi->nfs_page_tree,
-					req->wb_index, NFS_PAGE_TAG_DIRTY);
-			nfsi->ndirty--;
-			nfs_list_remove_request(req);
-			nfs_list_add_request(req, dst);
-			res++;
-			if (res == LONG_MAX)
-				goto out;
-next:
-			idx_start = req->wb_index + 1;
-		}
+/**
+ * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
+ * @desc: destination io descriptor
+ * @req: request
+ *
+ * Returns true if the request 'req' was successfully coalesced into the
+ * existing list of pages 'desc'.
+ */
+int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
+			   struct nfs_page *req)
+{
+	while (!nfs_pageio_do_add_request(desc, req)) {
+		nfs_pageio_doio(desc);
+		if (desc->pg_error < 0)
+			return 0;
 	}
-out:
-	WARN_ON ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty));
-	return res;
+	return 1;
 }
 
 /**
+ * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
+ * @desc: pointer to io descriptor
+ */
+void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
+{
+	nfs_pageio_doio(desc);
+}
+
+#define NFS_SCAN_MAXENTRIES 16
+/**
  * nfs_scan_list - Scan a list for matching requests
  * @nfsi: NFS inode
  * @head: One of the NFS inode request lists
@@ -355,12 +377,12 @@ out:
  * You must be holding the inode's req_lock when calling this function
  */
 int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *head,
-		struct list_head *dst, unsigned long idx_start,
+		struct list_head *dst, pgoff_t idx_start,
 		unsigned int npages)
 {
 	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
 	struct nfs_page *req;
-	unsigned long idx_end;
+	pgoff_t idx_end;
 	int found, i;
 	int res;