From 5dae222a5ff0c269730393018a5539cc970a4726 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Wed, 5 Jun 2019 08:04:50 -0700 Subject: vfs: allow copy_file_range to copy across devices We want to enable cross-filesystem copy_file_range functionality where possible, so push the "same superblock only" checks down to the individual filesystem callouts so they can make their own decisions about cross-superblock copy offload and fallack to generic_copy_file_range() for cross-superblock copy. [Amir] We do not call ->remap_file_range() in case the files are not on the same sb and do not call ->copy_file_range() in case the files do not belong to the same filesystem driver. This changes behavior of the copy_file_range(2) syscall, which will now allow cross filesystem in-kernel copy. CIFS already supports cross-superblock copy, between two shares to the same server. This functionality will now be available via the copy_file_range(2) syscall. Cc: Steve French Signed-off-by: Dave Chinner Signed-off-by: Amir Goldstein Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/read_write.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) (limited to 'fs/read_write.c') diff --git a/fs/read_write.c b/fs/read_write.c index cec7e7b1f693..1f5088dec566 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1599,7 +1599,16 @@ static ssize_t do_copy_file_range(struct file *file_in, loff_t pos_in, struct file *file_out, loff_t pos_out, size_t len, unsigned int flags) { - if (file_out->f_op->copy_file_range) + /* + * Although we now allow filesystems to handle cross sb copy, passing + * a file of the wrong filesystem type to filesystem driver can result + * in an attempt to dereference the wrong type of ->private_data, so + * avoid doing that until we really have a good reason. NFS defines + * several different file_system_type structures, but they all end up + * using the same ->copy_file_range() function pointer. + */ + if (file_out->f_op->copy_file_range && + file_out->f_op->copy_file_range == file_in->f_op->copy_file_range) return file_out->f_op->copy_file_range(file_in, pos_in, file_out, pos_out, len, flags); @@ -1622,10 +1631,6 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, if (flags != 0) return -EINVAL; - /* this could be relaxed once a method supports cross-fs copies */ - if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb) - return -EXDEV; - ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len, flags); if (unlikely(ret)) @@ -1648,7 +1653,8 @@ 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->remap_file_range) { + if (file_in->f_op->remap_file_range && + file_inode(file_in)->i_sb == file_inode(file_out)->i_sb) { loff_t cloned; cloned = file_in->f_op->remap_file_range(file_in, pos_in, -- cgit v1.2.3-55-g7522