On 11/01/2022 19:10, Sebastian Hasler wrote:
With the current implementation, blocking flock can lead to deadlock. Thus, it's better to return EOPNOTSUPP if a user attempts to perform a blocking flock request. Signed-off-by: Sebastian Hasler <sebastian.has...@stuvus.uni-stuttgart.de> --- tools/virtiofsd/passthrough_ll.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 64b5b4fbb1..f3cc307f6d 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -2442,6 +2442,12 @@ static void lo_flock(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, int res; (void)ino;+ if (!(op & LOCK_NB)) {+ /* Blocking flock is not supported */ + fuse_reply_err(req, EOPNOTSUPP); + return; + } + res = flock(lo_fi_fd(req, fi), op);fuse_reply_err(req, res == -1 ? errno : 0);
I tested this patch by cherry-picking it on v6.1.0 and using it with Kata Containers 2.3.0. The bash code
exec 42>/lock/flock flock -w 120 42 outputs flock: 42: Operation not supported while the bash code exec 42>/lock/flock flock --nonblock 42 still works. So it works as intended. -- Sebastian Hasler stuvus – Studierendenvertretung Universität Stuttgart
