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 <stfrench@microsoft.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index c65823270313..f11eea6125c1 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1149,7 +1149,7 @@ static ssize_t cifs_copy_file_range(struct file *src_file, loff_t off,
 					len, flags);
 	free_xid(xid);
 
-	if (rc == -EOPNOTSUPP)
+	if (rc == -EOPNOTSUPP || rc == -EXDEV)
 		rc = generic_copy_file_range(src_file, off, dst_file,
 					     destoff, len, flags);
 	return rc;