NFS: Fix another O_DIRECT race

 Ensure we call unmap_mapping_range() and sync dirty pages to disk before
 doing an NFS direct write.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/direct.c

@@ -678,15 +678,9 @@ nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t
 	if (!count)
 		goto out;
 
-	if (mapping->nrpages) {
-		retval = filemap_fdatawrite(mapping);
-		if (retval == 0)
-			retval = nfs_wb_all(inode);
-		if (retval == 0)
-			retval = filemap_fdatawait(mapping);
-		if (retval)
-			goto out;
-	}
+	retval = nfs_sync_mapping(mapping);
+	if (retval)
+		goto out;
 
 	retval = nfs_direct_read(inode, ctx, &iov, pos, 1);
 	if (retval > 0)
@@ -764,15 +758,9 @@ nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t count,
 	if (!count)
 		goto out;
 
-	if (mapping->nrpages) {
-		retval = filemap_fdatawrite(mapping);
-		if (retval == 0)
-			retval = nfs_wb_all(inode);
-		if (retval == 0)
-			retval = filemap_fdatawait(mapping);
-		if (retval)
-			goto out;
-	}
+	retval = nfs_sync_mapping(mapping);
+	if (retval)
+		goto out;
 
 	retval = nfs_direct_write(inode, ctx, &iov, pos, 1);
 	if (mapping->nrpages)

fs/nfs/file.c

@@ -433,11 +433,7 @@ static int do_unlk(struct file *filp, int cmd, struct file_lock *fl)
 	 * Flush all pending writes before doing anything
 	 * with locks..
 	 */
-	filemap_fdatawrite(filp->f_mapping);
-	down(&inode->i_sem);
-	nfs_wb_all(inode);
-	up(&inode->i_sem);
-	filemap_fdatawait(filp->f_mapping);
+	nfs_sync_mapping(filp->f_mapping);
 
 	/* NOTE: special case
 	 * 	If we're signalled while cleaning up locks on process exit, we
@@ -465,15 +461,8 @@ static int do_setlk(struct file *filp, int cmd, struct file_lock *fl)
 	 * Flush all pending writes before doing anything
 	 * with locks..
 	 */
-	status = filemap_fdatawrite(filp->f_mapping);
-	if (status == 0) {
-		down(&inode->i_sem);
-		status = nfs_wb_all(inode);
-		up(&inode->i_sem);
-		if (status == 0)
-			status = filemap_fdatawait(filp->f_mapping);
-	}
-	if (status < 0)
+	status = nfs_sync_mapping(filp->f_mapping);
+	if (status != 0)
 		goto out;
 
 	lock_kernel();
@@ -497,11 +486,7 @@ static int do_setlk(struct file *filp, int cmd, struct file_lock *fl)
 	 * Make sure we clear the cache whenever we try to get the lock.
 	 * This makes locking act as a cache coherency point.
 	 */
-	filemap_fdatawrite(filp->f_mapping);
-	down(&inode->i_sem);
-	nfs_wb_all(inode);	/* we may have slept */
-	up(&inode->i_sem);
-	filemap_fdatawait(filp->f_mapping);
+	nfs_sync_mapping(filp->f_mapping);
 	nfs_zap_caches(inode);
 out:
 	rpc_clnt_sigunmask(NFS_CLIENT(inode), &oldset);

fs/nfs/inode.c

@@ -640,6 +640,27 @@ static int nfs_show_options(struct seq_file *m, struct vfsmount *mnt)
 	return 0;
 }
 
+/**
+ * nfs_sync_mapping - helper to flush all mmapped dirty data to disk
+ */
+int nfs_sync_mapping(struct address_space *mapping)
+{
+	int ret;
+
+	if (mapping->nrpages == 0)
+		return 0;
+	unmap_mapping_range(mapping, 0, 0, 0);
+	ret = filemap_fdatawrite(mapping);
+	if (ret != 0)
+		goto out;
+	ret = filemap_fdatawait(mapping);
+	if (ret != 0)
+		goto out;
+	ret = nfs_wb_all(mapping->host);
+out:
+	return ret;
+}
+
 /*
  * Invalidate the local caches
  */
@@ -1179,11 +1200,8 @@ void nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
 	struct nfs_inode *nfsi = NFS_I(inode);
 
 	if (nfsi->cache_validity & NFS_INO_INVALID_DATA) {
-		if (S_ISREG(inode->i_mode)) {
-			if (filemap_fdatawrite(mapping) == 0)
-				filemap_fdatawait(mapping);
-			nfs_wb_all(inode);
-		}
+		if (S_ISREG(inode->i_mode))
+			nfs_sync_mapping(mapping);
 		invalidate_inode_pages2(mapping);
 
 		spin_lock(&inode->i_lock);

include/linux/nfs_fs.h

@@ -291,6 +291,7 @@ static inline int nfs_verify_change_attribute(struct inode *inode, unsigned long
 /*
  * linux/fs/nfs/inode.c
  */
+extern int nfs_sync_mapping(struct address_space *mapping);
 extern void nfs_zap_caches(struct inode *);
 extern struct inode *nfs_fhget(struct super_block *, struct nfs_fh *,
 				struct nfs_fattr *);