From b590eb41be766c5a63acc7e8896a042f7a4e8293 Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Wed, 1 Nov 2023 22:03:28 +0000
Subject: [PATCH] afs: Fix file locking on R/O volumes to operate in local mode
Git-commit: b590eb41be766c5a63acc7e8896a042f7a4e8293
Patch-mainline: v6.7-rc3
References: git-fixes

AFS doesn't really do locking on R/O volumes as fileservers don't maintain
state with each other and thus a lock on a R/O volume file on one
fileserver will not be be visible to someone looking at the same file on
another fileserver.

Further, the server may return an error if you try it.

Fix this by doing what other AFS clients do and handle filelocking on R/O
volume files entirely within the client and don't touch the server.

Fixes: 6c6c1d63c243 ("afs: Provide mount-time configurable byte-range file locking emulation")
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
Cc: linux-afs@lists.infradead.org
Acked-by: Anthony Iliopoulos <ailiop@suse.com>

---
 fs/afs/super.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/afs/super.c b/fs/afs/super.c
index 95d713074dc8..e95fb4cb4fcd 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -407,6 +407,8 @@ static int afs_validate_fc(struct fs_context *fc)
 			return PTR_ERR(volume);
 
 		ctx->volume = volume;
+		if (volume->type != AFSVL_RWVOL)
+			ctx->flock_mode = afs_flock_mode_local;
 	}
 
 	return 0;
-- 
2.43.0