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authorSebastian Hasler <sebastian.hasler@stuvus.uni-stuttgart.de>2022-01-13 16:32:49 +0100
committerDr. David Alan Gilbert <dgilbert@redhat.com>2022-02-16 17:29:31 +0000
commit41af4459ac47e107093c3f54b6875d54723aa613 (patch)
tree85cef71580611193c403b071c403a304c69ee789 /tools/virtiofsd/passthrough_ll.c
parentc13b8e9973635f34f3ce4356af27a311c993729c (diff)
virtiofsd: Do not support blocking flock
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.hasler@stuvus.uni-stuttgart.de> Message-Id: <20220113153249.710216-1-sebastian.hasler@stuvus.uni-stuttgart.de> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Greg Kurz <groug@kaod.org>
Diffstat (limited to 'tools/virtiofsd/passthrough_ll.c')
-rw-r--r--tools/virtiofsd/passthrough_ll.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index b3d0674f6d..3e56d1cd95 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -2467,6 +2467,15 @@ 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 can deadlock as there is only one thread
+ * serving the queue.
+ */
+ fuse_reply_err(req, EOPNOTSUPP);
+ return;
+ }
+
res = flock(lo_fi_fd(req, fi), op);
fuse_reply_err(req, res == -1 ? errno : 0);