[PATCH] btrfs: send: gate SEND_A_MAX and SEND_C_MAX V3

[PATCH] btrfs: send: gate SEND_A_MAX and SEND_C_MAX V3

[Boris Burkov]

We haven't finalized send stream v3 yet, so gate setting the max command
values behind CONFIG_BTRFS_DEBUG.

In my testing, and judging from the code, this is a cosmetic change;
verity send commands are still produced (and processed by a compatible
btrfs-progs), even with CONFIG_BTRFS_DEBUG=n set.

Signed-off-by: Boris Burkov <boris@bur.io>
---
 fs/btrfs/send.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/fs/btrfs/send.h b/fs/btrfs/send.h
index 0a4537775e0c..23661b37ea64 100644
--- a/fs/btrfs/send.h
+++ b/fs/btrfs/send.h
@@ -94,9 +94,13 @@ enum btrfs_send_cmd {
 
 	/* Version 3 */
 	BTRFS_SEND_C_ENABLE_VERITY	= 26,
+#ifndef CONFIG_BTRFS_DEBUG
+	BTRFS_SEND_C_MAX		= 25,
+#else
 	BTRFS_SEND_C_MAX_V3		= 26,
 	/* End */
 	BTRFS_SEND_C_MAX		= 26,
+#endif
 };
 
 /* attributes in send stream */
@@ -168,9 +172,14 @@ enum {
 	BTRFS_SEND_A_VERITY_BLOCK_SIZE	= 33,
 	BTRFS_SEND_A_VERITY_SALT_DATA	= 34,
 	BTRFS_SEND_A_VERITY_SIG_DATA	= 35,
+
+#ifndef CONFIG_BTRFS_DEBUG
+	__BTRFS_SEND_A_MAX		= 31,
+#else
 	BTRFS_SEND_A_MAX_V3		= 35,
 
 	__BTRFS_SEND_A_MAX		= 35,
+#endif
 };
 
 long btrfs_ioctl_send(struct inode *inode, struct btrfs_ioctl_send_args *arg);
-- 
2.37.2

Re: [PATCH] btrfs: send: gate SEND_A_MAX and SEND_C_MAX V3

[David Sterba]

On Mon, Sep 26, 2022 at 11:15:22AM -0700, Boris Burkov wrote:
> We haven't finalized send stream v3 yet, so gate setting the max command
> values behind CONFIG_BTRFS_DEBUG.
> 
> In my testing, and judging from the code, this is a cosmetic change;
> verity send commands are still produced (and processed by a compatible
> btrfs-progs), even with CONFIG_BTRFS_DEBUG=n set.

There must be some misunderstanding and what you implemented is not what
I had in mind. The debug protection should have been for
BTRFS_SEND_STREAM_VERSION so we have v3 available for debug builds and
not otherwise. The version support is not determined by the command
definitions but by the BTRFS_SEND_STREAM_VERSION macro exported to
sysfs.

Re: [PATCH] btrfs: send: gate SEND_A_MAX and SEND_C_MAX V3

[Boris Burkov]

On Tue, Sep 27, 2022 at 02:24:12PM +0200, David Sterba wrote:
> On Mon, Sep 26, 2022 at 11:15:22AM -0700, Boris Burkov wrote:
> > We haven't finalized send stream v3 yet, so gate setting the max command
> > values behind CONFIG_BTRFS_DEBUG.
> > 
> > In my testing, and judging from the code, this is a cosmetic change;
> > verity send commands are still produced (and processed by a compatible
> > btrfs-progs), even with CONFIG_BTRFS_DEBUG=n set.
> 
> There must be some misunderstanding and what you implemented is not what
> I had in mind. The debug protection should have been for
> BTRFS_SEND_STREAM_VERSION so we have v3 available for debug builds and
> not otherwise. The version support is not determined by the command
> definitions but by the BTRFS_SEND_STREAM_VERSION macro exported to
> sysfs.

This makes way more sense, thanks! Working on fixing it. I will also
block sending verity based on the proto being >= 3. Sorry for
misunderstanding you in the first place.