NFS: Write the entire file if a server reboot occurs during fsync()

This is to ensure that we don't clear the NFS_CONTEXT_RESEND_WRITES
flag while there are still writes that haven't been resent.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/file.c

@@ -301,6 +301,13 @@ nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 		mutex_lock(&inode->i_mutex);
 		ret = nfs_file_fsync_commit(file, start, end, datasync);
 		mutex_unlock(&inode->i_mutex);
+		/*
+		 * If nfs_file_fsync_commit detected a server reboot, then
+		 * resend all dirty pages that might have been covered by
+		 * the NFS_CONTEXT_RESEND_WRITES flag
+		 */
+		start = 0;
+		end = LLONG_MAX;
 	} while (ret == -EAGAIN);
 
 	return ret;

fs/nfs/nfs4file.c

@@ -105,6 +105,13 @@ nfs4_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 			/* application has asked for meta-data sync */
 			ret = pnfs_layoutcommit_inode(inode, true);
 		mutex_unlock(&inode->i_mutex);
+		/*
+		 * If nfs_file_fsync_commit detected a server reboot, then
+		 * resend all dirty pages that might have been covered by
+		 * the NFS_CONTEXT_RESEND_WRITES flag
+		 */
+		start = 0;
+		end = LLONG_MAX;
 	} while (ret == -EAGAIN);
 
 	return ret;