NFS: Convert struct nfs_page to use krefs

Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/pagelist.c

@@ -85,9 +85,8 @@ nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
 	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);
-
+	kref_init(&req->wb_kref);
 	return req;
 }
 
@@ -160,11 +159,9 @@ void nfs_clear_request(struct nfs_page *req)
  *
  * Note: Should never be called with the spinlock held!
  */
-void
-nfs_release_request(struct nfs_page *req)
+static void nfs_free_request(struct kref *kref)
 {
-	if (!atomic_dec_and_test(&req->wb_count))
-		return;
+	struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 
 	/* Release struct file or cached credential */
 	nfs_clear_request(req);
@@ -172,6 +169,11 @@ nfs_release_request(struct nfs_page *req)
 	nfs_page_free(req);
 }
 
+void nfs_release_request(struct nfs_page *req)
+{
+	kref_put(&req->wb_kref, nfs_free_request);
+}
+
 static int nfs_wait_bit_interruptible(void *word)
 {
 	int ret = 0;

fs/nfs/write.c

@@ -117,7 +117,7 @@ static struct nfs_page *nfs_page_find_request_locked(struct page *page)
 	if (PagePrivate(page)) {
 		req = (struct nfs_page *)page_private(page);
 		if (req != NULL)
-			atomic_inc(&req->wb_count);
+			kref_get(&req->wb_kref);
 	}
 	return req;
 }
@@ -398,7 +398,7 @@ static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
 	if (PageDirty(req->wb_page))
 		set_bit(PG_NEED_FLUSH, &req->wb_flags);
 	nfsi->npages++;
-	atomic_inc(&req->wb_count);
+	kref_get(&req->wb_kref);
 	return 0;
 }
 
@@ -531,7 +531,7 @@ static int nfs_wait_on_requests_locked(struct inode *inode, pgoff_t idx_start, u
 		next = req->wb_index + 1;
 		BUG_ON(!NFS_WBACK_BUSY(req));
 
-		atomic_inc(&req->wb_count);
+		kref_get(&req->wb_kref);
 		spin_unlock(&nfsi->req_lock);
 		error = nfs_wait_on_request(req);
 		nfs_release_request(req);

include/linux/nfs_page.h

@@ -16,7 +16,7 @@
 #include <linux/sunrpc/auth.h>
 #include <linux/nfs_xdr.h>
 
-#include <asm/atomic.h>
+#include <linux/kref.h>
 
 /*
  * Valid flags for the radix tree
@@ -42,7 +42,7 @@ struct nfs_page {
 	unsigned int		wb_offset,	/* Offset & ~PAGE_CACHE_MASK */
 				wb_pgbase,	/* Start of page data */
 				wb_bytes;	/* Length of request */
-	atomic_t		wb_count;	/* reference count */
+	struct kref		wb_kref;	/* reference count */
 	unsigned long		wb_flags;
 	struct nfs_writeverf	wb_verf;	/* Commit cookie */
 };
@@ -89,7 +89,7 @@ extern  void nfs_clear_page_writeback(struct nfs_page *req);
 
 
 /*
- * Lock the page of an asynchronous request without incrementing the wb_count
+ * Lock the page of an asynchronous request without getting a new reference
  */
 static inline int
 nfs_lock_request_dontget(struct nfs_page *req)
@@ -98,14 +98,14 @@ nfs_lock_request_dontget(struct nfs_page *req)
 }
 
 /*
- * Lock the page of an asynchronous request
+ * Lock the page of an asynchronous request and take a reference
  */
 static inline int
 nfs_lock_request(struct nfs_page *req)
 {
 	if (test_and_set_bit(PG_BUSY, &req->wb_flags))
 		return 0;
-	atomic_inc(&req->wb_count);
+	kref_get(&req->wb_kref);
 	return 1;
 }