linux/copy_file_range: properly request a fallback copy on Linux <5.3

Before Linux 5.3, the filesystem's copy_file_range handler had to signal back to the kernel that we can't fulfull the request and it should fallback to a content copy. This is done by returning -EOPNOTSUPP. This commit converts the EXDEV return from zfs_clone_range to EOPNOTSUPP, to force the kernel to fallback for all the valid reasons it might be unable to clone. Without it the copy_file_range() syscall will return EXDEV to userspace, breaking its semantics. Signed-off-by: Rob Norris <[email protected]>
openzfs · Aug 1, 2023 · 88de7b3 · 88de7b3
1 parent 89e861b
commit 88de7b3
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/module/os/linux/zfs/zpl_file_range.c b/module/os/linux/zfs/zpl_file_range.c
@@ -106,6 +106,13 @@ zpl_copy_file_range(struct file *src_file, loff_t src_off,
 	if (ret == -EOPNOTSUPP || ret == -EXDEV)
 		ret = generic_copy_file_range(src_file, src_off, dst_file,
 		    dst_off, len, flags);
+#else
+	/*
+	 * Before Linux 5.3 the filesystem has to return -EOPNOTSUPP to signal
+	 * to the kernel that it should fallback to a content copy.
+	 */
+	if (ret == -EXDEV)
+		ret = -EOPNOTSUPP;
 #endif /* HAVE_VFS_GENERIC_COPY_FILE_RANGE */
 
 	return (ret);