fs-verity: rename "file measurement" to "file digest"

I originally chose the name "file measurement" to refer to the fs-verity
file digest to avoid confusion with traditional full-file digests or
with the bare root hash of the Merkle tree.

But the name "file measurement" hasn't caught on, and usually people are
calling it something else, usually the "file digest".  E.g. see
"struct fsverity_digest" and "struct fsverity_formatted_digest", the
libfsverity_compute_digest() and libfsverity_sign_digest() functions in
libfsverity, and the "fsverity digest" command.

Having multiple names for the same thing is always confusing.

So to hopefully avoid confusion in the future, rename
"fs-verity file measurement" to "fs-verity file digest".

This leaves FS_IOC_MEASURE_VERITY as the only reference to "measure" in
the kernel, which makes some amount of sense since the ioctl is actively
"measuring" the file.

I'll be renaming this in fsverity-utils too (though similarly the
'fsverity measure' command, which is a wrapper for
FS_IOC_MEASURE_VERITY, will stay).

Acked-by: Luca Boccassi <luca.boccassi@microsoft.com>
Link: https://lore.kernel.org/r/20201113211918.71883-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/fs/verity/measure.c b/fs/verity/measure.c
index 5300b8d38537..f0d7b30c62db 100644
--- a/fs/verity/measure.c
+++ b/fs/verity/measure.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Ioctl to get a verity file's measurement
+ * Ioctl to get a verity file's digest
  *
  * Copyright 2019 Google LLC
  */
@@ -10,12 +10,12 @@
 #include <linux/uaccess.h>
 
 /**
- * fsverity_ioctl_measure() - get a verity file's measurement
- * @filp: file to get measurement of
+ * fsverity_ioctl_measure() - get a verity file's digest
+ * @filp: file to get digest of
  * @_uarg: user pointer to fsverity_digest
  *
- * Retrieve the file measurement that the kernel is enforcing for reads from a
- * verity file.  See the "FS_IOC_MEASURE_VERITY" section of
+ * Retrieve the file digest that the kernel is enforcing for reads from a verity
+ * file.  See the "FS_IOC_MEASURE_VERITY" section of
  * Documentation/filesystems/fsverity.rst for the documentation.
  *
  * Return: 0 on success, -errno on failure
@@ -51,7 +51,7 @@ int fsverity_ioctl_measure(struct file *filp, void __user *_uarg)
 	if (copy_to_user(uarg, &arg, sizeof(arg)))
 		return -EFAULT;
 
-	if (copy_to_user(uarg->digest, vi->measurement, hash_alg->digest_size))
+	if (copy_to_user(uarg->digest, vi->file_digest, hash_alg->digest_size))
 		return -EFAULT;
 
 	return 0;