vfs: deny copy_file_range() for non regular files

There is no in-tree file system that implements copy_file_range()
for non regular files.

Deny an attempt to copy_file_range() a directory with EISDIR
and any other non regualr file with EINVAL to conform with
behavior of vfs_{clone,dedup}_file_range().

This change is needed prior to converting sb_start_write()
to  file_start_write() in the vfs helper.

Cc: linux-api@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index 5816d4c4cab0..511178d7723b 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1518,6 +1518,11 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
         if (flags != 0)
                 return -EINVAL;
 
+        if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
+                return -EISDIR;
+        if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
+                return -EINVAL;
+
         ret = rw_verify_area(READ, file_in, &pos_in, len);
         if (unlikely(ret))
                 return ret;