[PULL 5/8] virtiofsd: Disable remote posix locks by default

["Dr. David Alan Gilbert (git)" <dgilbert@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>
---
 docs/tools/virtiofsd.rst         | 2 +-
 tools/virtiofsd/passthrough_ll.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/docs/tools/virtiofsd.rst b/docs/tools/virtiofsd.rst
index 824e713491..2cfdfd9ba2 100644
--- a/docs/tools/virtiofsd.rst
+++ b/docs/tools/virtiofsd.rst
@@ -67,7 +67,7 @@ Options
     Disable racy fallback.  The default is false.
 
   * posix_lock|no_posix_lock -
-    Enable/disable remote POSIX locks.  The default is ``posix_lock``.
+    Enable/disable remote POSIX locks.  The default is ``no_posix_lock``.
 
   * readdirplus|no_readdirplus -
     Enable/disable readdirplus.  The default is ``readdirplus``.
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 63d1d00565..a9feb90fd0 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -2823,7 +2823,7 @@ 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;
-- 
2.26.2