Re: [PATCH v5 8/9] vfs: Add vfs_copy_file_range() support for pagecache copies

On 10/07/2015 09:40 PM, Neil Brown wrote:

Anna Schumaker [off-list ref] writes:

quoted

@@ -1338,34 +1362,26 @@ ssize_t vfs_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)
 {
-	struct inode *inode_in;
-	struct inode *inode_out;
 	ssize_t ret;
 
-	if (flags)
+	/* Flags should only be used exclusively. */
+	if ((flags & COPY_FR_COPY) && (flags & ~COPY_FR_COPY))
+		return -EINVAL;
+	if ((flags & COPY_FR_REFLINK) && (flags & ~COPY_FR_REFLINK))
+		return -EINVAL;
+	if ((flags & COPY_FR_DEDUP) && (flags & ~COPY_FR_DEDUP))
 		return -EINVAL;
 

Do you also need:

   if (flags & ~(COPY_FR_COPY | COPY_FR_REFLINK | COPY_FR_DEDUP))
   	return -EINVAL;

so that future user-space can test if the kernel supports new flags?

Probably.  I'll add that in!

Thanks,
Anna

NeilBrown