1 files changed, 28 insertions, 42 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index b65aee481d13..5b1eee4952b7 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -857,15 +857,14 @@ static void nfs_init_lock_context(struct nfs_lock_context *l_ctx)
 
 static struct nfs_lock_context *__nfs_find_lock_context(struct nfs_open_context *ctx)
 {
-	struct nfs_lock_context *head = &ctx->lock_context;
-	struct nfs_lock_context *pos = head;
+	struct nfs_lock_context *pos;
 
-	do {
+	list_for_each_entry_rcu(pos, &ctx->lock_context.list, list) {
 		if (pos->lockowner != current->files)
 			continue;
-		refcount_inc(&pos->count);
-		return pos;
-	} while ((pos = list_entry(pos->list.next, typeof(*pos), list)) != head);
+		if (refcount_inc_not_zero(&pos->count))
+			return pos;
+	}
 	return NULL;
 }
 
@@ -874,10 +873,10 @@ struct nfs_lock_context *nfs_get_lock_context(struct nfs_open_context *ctx)
 	struct nfs_lock_context *res, *new = NULL;
 	struct inode *inode = d_inode(ctx->dentry);
 
-	spin_lock(&inode->i_lock);
+	rcu_read_lock();
 	res = __nfs_find_lock_context(ctx);
+	rcu_read_unlock();
 	if (res == NULL) {
-		spin_unlock(&inode->i_lock);
 		new = kmalloc(sizeof(*new), GFP_KERNEL);
 		if (new == NULL)
 			return ERR_PTR(-ENOMEM);
@@ -885,14 +884,14 @@ struct nfs_lock_context *nfs_get_lock_context(struct nfs_open_context *ctx)
 		spin_lock(&inode->i_lock);
 		res = __nfs_find_lock_context(ctx);
 		if (res == NULL) {
-			list_add_tail(&new->list, &ctx->lock_context.list);
+			list_add_tail_rcu(&new->list, &ctx->lock_context.list);
 			new->open_context = ctx;
 			res = new;
 			new = NULL;
 		}
+		spin_unlock(&inode->i_lock);
+		kfree(new);
 	}
-	spin_unlock(&inode->i_lock);
-	kfree(new);
 	return res;
 }
 EXPORT_SYMBOL_GPL(nfs_get_lock_context);
@@ -904,9 +903,9 @@ void nfs_put_lock_context(struct nfs_lock_context *l_ctx)
 
 	if (!refcount_dec_and_lock(&l_ctx->count, &inode->i_lock))
 		return;
-	list_del(&l_ctx->list);
+	list_del_rcu(&l_ctx->list);
 	spin_unlock(&inode->i_lock);
-	kfree(l_ctx);
+	kfree_rcu(l_ctx, rcu_head);
 }
 EXPORT_SYMBOL_GPL(nfs_put_lock_context);
 
@@ -978,9 +977,9 @@ EXPORT_SYMBOL_GPL(alloc_nfs_open_context);
 
 struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx)
 {
-	if (ctx != NULL)
-		refcount_inc(&ctx->lock_context.count);
-	return ctx;
+	if (ctx != NULL && refcount_inc_not_zero(&ctx->lock_context.count))
+		return ctx;
+	return NULL;
 }
 EXPORT_SYMBOL_GPL(get_nfs_open_context);
 
@@ -989,13 +988,13 @@ static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync)
 	struct inode *inode = d_inode(ctx->dentry);
 	struct super_block *sb = ctx->dentry->d_sb;
 
+	if (!refcount_dec_and_test(&ctx->lock_context.count))
+		return;
 	if (!list_empty(&ctx->list)) {
-		if (!refcount_dec_and_lock(&ctx->lock_context.count, &inode->i_lock))
-			return;
-		list_del(&ctx->list);
+		spin_lock(&inode->i_lock);
+		list_del_rcu(&ctx->list);
 		spin_unlock(&inode->i_lock);
-	} else if (!refcount_dec_and_test(&ctx->lock_context.count))
-		return;
+	}
 	if (inode != NULL)
 		NFS_PROTO(inode)->close_context(ctx, is_sync);
 	if (ctx->cred != NULL)
@@ -1003,7 +1002,7 @@ static void __put_nfs_open_context(struct nfs_open_context *ctx, int is_sync)
 	dput(ctx->dentry);
 	nfs_sb_deactive(sb);
 	kfree(ctx->mdsthreshold);
-	kfree(ctx);
+	kfree_rcu(ctx, rcu_head);
 }
 
 void put_nfs_open_context(struct nfs_open_context *ctx)
@@ -1027,10 +1026,7 @@ void nfs_inode_attach_open_context(struct nfs_open_context *ctx)
 	struct nfs_inode *nfsi = NFS_I(inode);
 
 	spin_lock(&inode->i_lock);
-	if (ctx->mode & FMODE_WRITE)
-		list_add(&ctx->list, &nfsi->open_files);
-	else
-		list_add_tail(&ctx->list, &nfsi->open_files);
+	list_add_tail_rcu(&ctx->list, &nfsi->open_files);
 	spin_unlock(&inode->i_lock);
 }
 EXPORT_SYMBOL_GPL(nfs_inode_attach_open_context);
@@ -1051,16 +1047,17 @@ struct nfs_open_context *nfs_find_open_context(struct inode *inode, struct rpc_c
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct nfs_open_context *pos, *ctx = NULL;
 
-	spin_lock(&inode->i_lock);
-	list_for_each_entry(pos, &nfsi->open_files, list) {
+	rcu_read_lock();
+	list_for_each_entry_rcu(pos, &nfsi->open_files, list) {
 		if (cred != NULL && pos->cred != cred)
 			continue;
 		if ((pos->mode & (FMODE_READ|FMODE_WRITE)) != mode)
 			continue;
 		ctx = get_nfs_open_context(pos);
-		break;
+		if (ctx)
+			break;
 	}
-	spin_unlock(&inode->i_lock);
+	rcu_read_unlock();
 	return ctx;
 }
 
@@ -1078,9 +1075,6 @@ void nfs_file_clear_open_context(struct file *filp)
 		if (ctx->error < 0)
 			invalidate_inode_pages2(inode->i_mapping);
 		filp->private_data = NULL;
-		spin_lock(&inode->i_lock);
-		list_move_tail(&ctx->list, &NFS_I(inode)->open_files);
-		spin_unlock(&inode->i_lock);
 		put_nfs_open_context_sync(ctx);
 	}
 }
@@ -1329,19 +1323,11 @@ static bool nfs_file_has_writers(struct nfs_inode *nfsi)
 {
 	struct inode *inode = &nfsi->vfs_inode;
 
-	assert_spin_locked(&inode->i_lock);
-
 	if (!S_ISREG(inode->i_mode))
 		return false;
 	if (list_empty(&nfsi->open_files))
 		return false;
-	/* Note: This relies on nfsi->open_files being ordered with writers
-	 *       being placed at the head of the list.
-	 *       See nfs_inode_attach_open_context()
-	 */
-	return (list_first_entry(&nfsi->open_files,
-			struct nfs_open_context,
-			list)->mode & FMODE_WRITE) == FMODE_WRITE;
+	return inode_is_open_for_write(inode);
 }
 
 static bool nfs_file_has_buffered_writers(struct nfs_inode *nfsi)