From 3ec945ba7c2649cca13cf6070c6365b1262ad1ec Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Fri, 6 Aug 2021 11:58:26 -0400
Subject: [PATCH 1/2] virtiofsd: Disable remote posix locks by default
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RH-Author: Max Reitz <mreitz@redhat.com>
Message-id: <20210806115827.740945-2-mreitz@redhat.com>
Patchwork-id: 101970
O-Subject: [RHEL-8.5.0 qemu-kvm PATCH 1/2] virtiofsd: Disable remote posix locks by default
Bugzilla: 1967496
RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>
RH-Acked-by: Vivek Goyal <vgoyal@redhat.com>

From: Vivek Goyal <vgoyal@redhat.com>

Right now we enable remote posix locks by default. That means when guest
does a posix lock it sends request to server (virtiofsd). But currently
we only support non-blocking posix lock and return -EOPNOTSUPP for
blocking version.

This means that existing applications which are doing blocking posix
locks get -EOPNOTSUPP and fail. To avoid this, people have been
running virtiosd with option "-o no_posix_lock". For new users it
is still a surprise and trial and error takes them to this option.

Given posix lock implementation is not complete in virtiofsd, disable
it by default. This means that posix locks will work with-in applications
in a guest but not across guests. Anyway we don't support sharing
filesystem among different guests yet in virtiofs so this should
not lead to any kind of surprise or regression and will make life
little easier for virtiofs users.

Reported-by: Aa Aa <jimbothom@yandex.com>
Suggested-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
(cherry picked from commit 88fc107956a5812649e5918e0c092d3f78bb28ad)

Conflicts:
	docs/tools/virtiofsd.rst
	We do not have virtiofsd.rst downstream (added upstream in
	commit 6a7e2bbee5fa), so I dropped that hunk (which effectively
	updated the default value in the man page).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 tools/virtiofsd/passthrough_ll.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index cb0992f2db..b47029da89 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -3001,7 +3001,7 @@ int main(int argc, char *argv[])
     struct lo_data lo = {
         .debug = 0,
         .writeback = 0,
-        .posix_lock = 1,
+        .posix_lock = 0,
         .proc_self_fd = -1,
     };
     struct lo_map_elem *root_elem;
-- 
2.27.0