NFS: Clean up nfs_scan_dirty()

Pass down struct writeback control.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/pagelist.c

@@ -17,6 +17,7 @@
 #include <linux/nfs_page.h>
 #include <linux/nfs_fs.h>
 #include <linux/nfs_mount.h>
+#include <linux/writeback.h>
 
 #define NFS_PARANOIA 1
 
@@ -268,11 +269,10 @@ nfs_coalesce_requests(struct list_head *head, struct list_head *dst,
 
 #define NFS_SCAN_MAXENTRIES 16
 /**
- * nfs_scan_lock_dirty - Scan the radix tree for dirty requests
- * @nfsi: NFS inode
+ * nfs_scan_dirty - Scan the radix tree for dirty requests
+ * @mapping: pointer to address space
+ * @wbc: writeback_control structure
  * @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
@@ -280,46 +280,72 @@ nfs_coalesce_requests(struct list_head *head, struct list_head *dst,
  * 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_lock_dirty(struct nfs_inode *nfsi, struct list_head *dst,
-	      unsigned long idx_start, unsigned int npages)
+long nfs_scan_dirty(struct address_space *mapping,
+			struct writeback_control *wbc,
+			struct list_head *dst)
 {
+	struct nfs_inode *nfsi = NFS_I(mapping->host);
 	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
 	struct nfs_page *req;
-	unsigned long idx_end;
+	pgoff_t idx_start, idx_end;
+	long count = wbc->nr_to_write;
+	long res = 0;
 	int found, i;
-	int res;
 
-	res = 0;
-	if (npages == 0)
-		idx_end = ~0;
-	else
-		idx_end = idx_start + npages - 1;
+	if (nfsi->ndirty == 0 || count <= 0)
+		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;
+	}
 
 	for (;;) {
+		unsigned int toscan = NFS_SCAN_MAXENTRIES;
+
+		if (toscan > count)
+			toscan = count;
 		found = radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree,
-				(void **)&pgvec[0], idx_start, NFS_SCAN_MAXENTRIES,
+				(void **)&pgvec[0], idx_start, toscan,
 				NFS_PAGE_TAG_DIRTY);
+
+		/* Did we make progress? */
 		if (found <= 0)
 			break;
+
 		for (i = 0; i < found; i++) {
 			req = pgvec[i];
-			if (req->wb_index > idx_end)
+			if (!wbc->range_cyclic && req->wb_index > idx_end)
 				goto out;
 
-			idx_start = req->wb_index + 1;
+			/* 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);
+			dec_zone_page_state(req->wb_page, NR_FILE_DIRTY);
+			res++;
+			if (res == LONG_MAX)
+				goto out;
+			count--;
+			if (count == 0)
+				goto out;
 
-			if (nfs_set_page_writeback_locked(req)) {
-				radix_tree_tag_clear(&nfsi->nfs_page_tree,
-						req->wb_index, NFS_PAGE_TAG_DIRTY);
-				nfs_list_remove_request(req);
-				nfs_list_add_request(req, dst);
-				dec_zone_page_state(req->wb_page, NR_FILE_DIRTY);
-				res++;
-			}
+next:
+			idx_start = req->wb_index + 1;
 		}
 	}
 out:
+	wbc->nr_to_write = count;
+	WARN_ON ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty));
 	return res;
 }
 

fs/nfs/write.c

@@ -79,7 +79,7 @@ static struct nfs_page * nfs_update_request(struct nfs_open_context*,
 					    unsigned int, unsigned int);
 static int nfs_wait_on_write_congestion(struct address_space *, int);
 static int nfs_wait_on_requests(struct inode *, unsigned long, unsigned int);
-static int nfs_flush_mapping(struct address_space *mapping, struct writeback_control *wbc, int how);
+static long nfs_flush_mapping(struct address_space *mapping, struct writeback_control *wbc, int how);
 static const struct rpc_call_ops nfs_write_partial_ops;
 static const struct rpc_call_ops nfs_write_full_ops;
 static const struct rpc_call_ops nfs_commit_ops;
@@ -400,10 +400,8 @@ int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 			goto out;
 	}
 	err = nfs_commit_inode(inode, wb_priority(wbc));
-	if (err > 0) {
-		wbc->nr_to_write -= err;
+	if (err > 0)
 		err = 0;
-	}
 out:
 	clear_bit(BDI_write_congested, &bdi->state);
 	wake_up_all(&nfs_write_congestion);
@@ -607,31 +605,6 @@ static void nfs_cancel_commit_list(struct list_head *head)
 	}
 }
 
-/*
- * nfs_scan_dirty - Scan an inode for dirty requests
- * @inode: NFS inode to scan
- * @dst: destination list
- * @idx_start: lower bound of page->index to scan.
- * @npages: idx_start + npages sets the upper bound to scan.
- *
- * Moves requests from the inode's dirty page list.
- * The requests are *not* checked to ensure that they form a contiguous set.
- */
-static int
-nfs_scan_dirty(struct inode *inode, struct list_head *dst, unsigned long idx_start, unsigned int npages)
-{
-	struct nfs_inode *nfsi = NFS_I(inode);
-	int res = 0;
-
-	if (nfsi->ndirty != 0) {
-		res = nfs_scan_lock_dirty(nfsi, dst, idx_start, npages);
-		nfsi->ndirty -= res;
-		if ((nfsi->ndirty == 0) != list_empty(&nfsi->dirty))
-			printk(KERN_ERR "NFS: desynchronized value of nfs_i.ndirty.\n");
-	}
-	return res;
-}
-
 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 /*
  * nfs_scan_commit - Scan an inode for commit requests
@@ -1467,22 +1440,19 @@ static inline int nfs_commit_list(struct inode *inode, struct list_head *head, i
 }
 #endif
 
-static int nfs_flush_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
+static long nfs_flush_mapping(struct address_space *mapping, struct writeback_control *wbc, int how)
 {
 	struct nfs_inode *nfsi = NFS_I(mapping->host);
 	LIST_HEAD(head);
-	pgoff_t index = wbc->range_start >> PAGE_CACHE_SHIFT;
-	unsigned long npages = 1 + (wbc->range_end >> PAGE_CACHE_SHIFT) - index;
-	int res;
+	long res;
 
 	spin_lock(&nfsi->req_lock);
-	res = nfs_scan_dirty(mapping->host, &head, index, npages);
+	res = nfs_scan_dirty(mapping, wbc, &head);
 	spin_unlock(&nfsi->req_lock);
 	if (res) {
 		int error = nfs_flush_list(mapping->host, &head, res, how);
 		if (error < 0)
 			return error;
-		wbc->nr_to_write -= res;
 	}
 	return res;
 }
@@ -1506,13 +1476,21 @@ int nfs_commit_inode(struct inode *inode, int how)
 }
 #endif
 
-int nfs_sync_inode_wait(struct inode *inode, unsigned long idx_start,
+long nfs_sync_inode_wait(struct inode *inode, unsigned long idx_start,
 		unsigned int npages, int how)
 {
 	struct nfs_inode *nfsi = NFS_I(inode);
+	struct address_space *mapping = inode->i_mapping;
+	struct writeback_control wbc = {
+		.bdi = mapping->backing_dev_info,
+		.sync_mode = WB_SYNC_ALL,
+		.nr_to_write = LONG_MAX,
+		.range_start = ((loff_t)idx_start) << PAGE_CACHE_SHIFT,
+		.range_end = ((loff_t)(idx_start + npages - 1)) << PAGE_CACHE_SHIFT,
+	};
 	LIST_HEAD(head);
 	int nocommit = how & FLUSH_NOCOMMIT;
-	int pages, ret;
+	long pages, ret;
 
 	how &= ~FLUSH_NOCOMMIT;
 	spin_lock(&nfsi->req_lock);
@@ -1520,7 +1498,7 @@ int nfs_sync_inode_wait(struct inode *inode, unsigned long idx_start,
 		ret = nfs_wait_on_requests_locked(inode, idx_start, npages);
 		if (ret != 0)
 			continue;
-		pages = nfs_scan_dirty(inode, &head, idx_start, npages);
+		pages = nfs_scan_dirty(mapping, &wbc, &head);
 		if (pages != 0) {
 			spin_unlock(&nfsi->req_lock);
 			if (how & FLUSH_INVALIDATE) {

include/linux/nfs_fs.h

@@ -432,7 +432,7 @@ extern void nfs_writedata_release(void *);
  * Try to write back everything synchronously (but check the
  * return value!)
  */
-extern int  nfs_sync_inode_wait(struct inode *, unsigned long, unsigned int, int);
+extern long nfs_sync_inode_wait(struct inode *, unsigned long, unsigned int, int);
 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
 extern int  nfs_commit_inode(struct inode *, int);
 extern struct nfs_write_data *nfs_commit_alloc(void);

include/linux/nfs_page.h

@@ -60,8 +60,9 @@ extern	void nfs_clear_request(struct nfs_page *req);
 extern	void nfs_release_request(struct nfs_page *req);
 
 
-extern  int nfs_scan_lock_dirty(struct nfs_inode *nfsi, struct list_head *dst,
-				unsigned long idx_start, unsigned int npages);
+extern	long nfs_scan_dirty(struct address_space *mapping,
+				struct writeback_control *wbc,
+				struct list_head *dst);
 extern	int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *head, struct list_head *dst,
 			  unsigned long idx_start, unsigned int npages);
 extern	int nfs_coalesce_requests(struct list_head *, struct list_head *,