[PATCH 1/3] virtiofsd: Add an option to enable/disable posix acls

[Vivek Goyal <vgoyal@redhat.com>]

fuse has an option FUSE_POSIX_ACL which needs to be opted in by fuse
server to enable posix acls.

Add virtiofsd option "-o posix_acl/no_posix_acl" to let users enable/disable
posix acl support. By default it is disabled as of now.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 tools/virtiofsd/passthrough_ll.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 147b59338a..34b2848e61 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -168,6 +168,7 @@ struct lo_data {
 
     /* An O_PATH file descriptor to /proc/self/fd/ */
     int proc_self_fd;
+    int user_posix_acl;
 };
 
 static const struct fuse_opt lo_opts[] = {
@@ -198,6 +199,8 @@ static const struct fuse_opt lo_opts[] = {
     { "allow_direct_io", offsetof(struct lo_data, allow_direct_io), 1 },
     { "no_allow_direct_io", offsetof(struct lo_data, allow_direct_io), 0 },
     { "announce_submounts", offsetof(struct lo_data, announce_submounts), 1 },
+    { "posix_acl", offsetof(struct lo_data, user_posix_acl), 1 },
+    { "no_posix_acl", offsetof(struct lo_data, user_posix_acl), 0 },
     FUSE_OPT_END
 };
 static bool use_syslog = false;
@@ -630,6 +633,23 @@ static void lo_init(void *userdata, struct fuse_conn_info *conn)
                  "does not support it\n");
         lo->announce_submounts = false;
     }
+
+    if (lo->user_posix_acl == 1) {
+        /*
+         * User explicitly asked for this option. Enable it unconditionally.
+         * If connection does not have this capability, it should fail
+         * in fuse_lowlevel.c
+         */
+        fuse_log(FUSE_LOG_DEBUG, "lo_init: enabling posix acl\n");
+        conn->want |= FUSE_CAP_POSIX_ACL;
+    } else {
+        /*
+         * Either user specified to disable posix_acl, or did not specify
+          * anything. In both the cases do not enable posix acl.
+         */
+        fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling posix_acl\n");
+        conn->want &= ~FUSE_CAP_POSIX_ACL;
+    }
 }
 
 static void lo_getattr(fuse_req_t req, fuse_ino_t ino,
@@ -3533,6 +3553,7 @@ int main(int argc, char *argv[])
         .posix_lock = 0,
         .allow_direct_io = 0,
         .proc_self_fd = -1,
+        .user_posix_acl = -1,
     };
     struct lo_map_elem *root_elem;
     struct lo_map_elem *reserve_elem;
-- 
2.25.4