NFS cleanup: speed up nfs_scan_commit using radix tree tags

Add a tag for requests that are waiting for a COMMIT
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/pagelist.c

@@ -381,10 +381,10 @@ void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
 /**
  * nfs_scan_list - Scan a list for matching requests
  * @nfsi: NFS inode
- * @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.
+ * @tag: tag to scan for
  *
  * Moves elements from one of the inode request lists.
  * If the number of requests is set to 0, the entire address_space
@@ -392,9 +392,9 @@ void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
  * 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 nfs_inode *nfsi, struct list_head *head,
+int nfs_scan_list(struct nfs_inode *nfsi,
 		struct list_head *dst, pgoff_t idx_start,
-		unsigned int npages)
+		unsigned int npages, int tag)
 {
 	struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
 	struct nfs_page *req;
@@ -409,9 +409,9 @@ int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *head,
 		idx_end = idx_start + npages - 1;
 
 	for (;;) {
-		found = radix_tree_gang_lookup(&nfsi->nfs_page_tree,
+		found = radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree,
 				(void **)&pgvec[0], idx_start,
-				NFS_SCAN_MAXENTRIES);
+				NFS_SCAN_MAXENTRIES, tag);
 		if (found <= 0)
 			break;
 		for (i = 0; i < found; i++) {
@@ -419,10 +419,10 @@ int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *head,
 			if (req->wb_index > idx_end)
 				goto out;
 			idx_start = req->wb_index + 1;
-			if (req->wb_list_head != head)
-				continue;
 			if (nfs_set_page_tag_locked(req)) {
 				nfs_list_remove_request(req);
+				radix_tree_tag_clear(&nfsi->nfs_page_tree,
+						req->wb_index, tag);
 				nfs_list_add_request(req, dst);
 				res++;
 			}

fs/nfs/write.c

@@ -462,6 +462,9 @@ nfs_mark_request_commit(struct nfs_page *req)
 	nfs_list_add_request(req, &nfsi->commit);
 	nfsi->ncommit++;
 	set_bit(PG_NEED_COMMIT, &(req)->wb_flags);
+	radix_tree_tag_set(&nfsi->nfs_page_tree,
+			req->wb_index,
+			NFS_PAGE_TAG_COMMIT);
 	spin_unlock(&nfsi->req_lock);
 	inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
 	__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
@@ -575,7 +578,8 @@ nfs_scan_commit(struct inode *inode, struct list_head *dst, pgoff_t idx_start, u
 	int res = 0;
 
 	if (nfsi->ncommit != 0) {
-		res = nfs_scan_list(nfsi, &nfsi->commit, dst, idx_start, npages);
+		res = nfs_scan_list(nfsi, dst, idx_start, npages,
+				NFS_PAGE_TAG_COMMIT);
 		nfsi->ncommit -= res;
 		if ((nfsi->ncommit == 0) != list_empty(&nfsi->commit))
 			printk(KERN_ERR "NFS: desynchronized value of nfs_i.ncommit.\n");

include/linux/nfs_page.h

@@ -22,6 +22,7 @@
  * Valid flags for the radix tree
  */
 #define NFS_PAGE_TAG_LOCKED	0
+#define NFS_PAGE_TAG_COMMIT	1
 
 /*
  * Valid flags for a dirty buffer
@@ -71,8 +72,8 @@ extern	void nfs_clear_request(struct nfs_page *req);
 extern	void nfs_release_request(struct nfs_page *req);
 
 
-extern	int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *head, struct list_head *dst,
-			  pgoff_t idx_start, unsigned int npages);
+extern	int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *dst,
+			  pgoff_t idx_start, unsigned int npages, int tag);
 extern	void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 			     struct inode *inode,
 			     int (*doio)(struct inode *, struct list_head *, unsigned int, size_t, int),