[PATCH v12 12/17] btrfs: send: fix maximum command numbering

[Omar Sandoval <osandov@osandov.com>]

From: Omar Sandoval <osandov@fb.com>

Commit e77fbf990316 ("btrfs: send: prepare for v2 protocol") added
_BTRFS_SEND_C_MAX_V* macros equal to the maximum command number for the
version plus 1, but as written this creates gaps in the number space.
The maximum command number is currently 22, and __BTRFS_SEND_C_MAX_V1 is
accordingly 23. But then __BTRFS_SEND_C_MAX_V2 is 24, suggesting that v2
has a command numbered 23, and __BTRFS_SEND_C_MAX is 25, suggesting that
23 and 24 are valid commands.

Instead, let's explicitly set BTRFS_SEND_C_MAX_V* to the maximum command
number. This requires repeating the command name, but it has a clearer
meaning and avoids gaps. It also doesn't require updating
__BTRFS_SEND_C_MAX for every new version.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 fs/btrfs/send.c | 4 ++--
 fs/btrfs/send.h | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 500b866ede43..450c873684e8 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -316,8 +316,8 @@ __maybe_unused
 static bool proto_cmd_ok(const struct send_ctx *sctx, int cmd)
 {
 	switch (sctx->proto) {
-	case 1:	 return cmd < __BTRFS_SEND_C_MAX_V1;
-	case 2:	 return cmd < __BTRFS_SEND_C_MAX_V2;
+	case 1:	 return cmd <= BTRFS_SEND_C_MAX_V1;
+	case 2:	 return cmd <= BTRFS_SEND_C_MAX_V2;
 	default: return false;
 	}
 }
diff --git a/fs/btrfs/send.h b/fs/btrfs/send.h
index 23bcefc84e49..59a4be3b09cd 100644
--- a/fs/btrfs/send.h
+++ b/fs/btrfs/send.h
@@ -77,10 +77,10 @@ enum btrfs_send_cmd {
 
 	BTRFS_SEND_C_END,
 	BTRFS_SEND_C_UPDATE_EXTENT,
-	__BTRFS_SEND_C_MAX_V1,
+	BTRFS_SEND_C_MAX_V1 = BTRFS_SEND_C_UPDATE_EXTENT,
 
 	/* Version 2 */
-	__BTRFS_SEND_C_MAX_V2,
+	BTRFS_SEND_C_MAX_V2 = BTRFS_SEND_C_MAX_V1,
 
 	/* End */
 	__BTRFS_SEND_C_MAX,
-- 
2.34.0