Return-Path: Received: from mx143.netapp.com ([216.240.21.24]:31729 "EHLO mx143.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751366AbdFZOtw (ORCPT ); Mon, 26 Jun 2017 10:49:52 -0400 From: Olga Kornievskaia To: , Subject: [PATCH 1/1] VFS permit cross device vfs_copy_file_range Date: Mon, 26 Jun 2017 10:49:43 -0400 Message-ID: <20170626144943.86070-1-kolga@netapp.com> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-nfs-owner@vger.kernel.org List-ID: Allow copy_file_range to copy between different superblocks but only of the same file system types. This feature is needed by NFSv4.2 to perform file copy operation on the same server or file copy between different NFSv4.2 servers. If a file system's fileoperations copy_file_range operation prohibits cross-device copies, fall back to do_splice_direct. This is needed for the NFS (destination) server side implementation of the file copy. Currently there is only 1 implementor of the copy_file_range FS operation -- CIFS. CIFS assumes incoming file descriptors are both CIFS but it will check if they are coming from different servers. NFS will allow for copies between different NFS servers. Adding to the vfs.txt documentation to explicitly warn about allowing for different superblocks of the same file type to be passed into the copy_file_range for the future users of copy_file_range method. Signed-off-by: Olga Kornievskaia --- Documentation/filesystems/vfs.txt | 7 +++++++ fs/read_write.c | 12 +++++------- 2 files changed, 12 insertions(+), 7 deletions(-) diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt index f42b906..cf22424 100644 --- a/Documentation/filesystems/vfs.txt +++ b/Documentation/filesystems/vfs.txt @@ -845,6 +845,8 @@ struct file_operations { #ifndef CONFIG_MMU unsigned (*mmap_capabilities)(struct file *); #endif + ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, + loff_t, size_t, unsigned int); }; Again, all methods are called without any locks being held, unless @@ -913,6 +915,11 @@ otherwise noted. fallocate: called by the VFS to preallocate blocks or punch a hole. + copy_file_range: called by copy_file_range(2) system call. This method + works on two file descriptors that might reside on + different superblocks of the same type of file system. + + Note that the file operations are implemented by the specific filesystem in which the inode resides. When opening a device node (character or block special) most filesystems will call special diff --git a/fs/read_write.c b/fs/read_write.c index 47c1d44..effbfb2 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1589,10 +1589,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, (file_out->f_flags & O_APPEND)) return -EBADF; - /* this could be relaxed once a method supports cross-fs copies */ - if (inode_in->i_sb != inode_out->i_sb) - return -EXDEV; - if (len == 0) return 0; @@ -1602,7 +1598,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, * Try cloning first, this is supported by more file systems, and * more efficient if both clone and copy are supported (e.g. NFS). */ - if (file_in->f_op->clone_file_range) { + if (inode_in->i_sb == inode_out->i_sb && + file_in->f_op->clone_file_range) { ret = file_in->f_op->clone_file_range(file_in, pos_in, file_out, pos_out, len); if (ret == 0) { @@ -1611,10 +1608,11 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, } } - if (file_out->f_op->copy_file_range) { + if (file_out->f_op->copy_file_range && + (file_in->f_op == file_out->f_op)) { ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, pos_out, len, flags); - if (ret != -EOPNOTSUPP) + if (ret != -EOPNOTSUPP && ret != -EXDEV) goto done; } -- 1.8.3.1