The branch main has been updated by asomers:
URL:
https://cgit.FreeBSD.org/src/commit/?id=9e682c426093a3afc0f609a1f04048b0beb021ec
commit 9e682c426093a3afc0f609a1f04048b0beb021ec
Author: Alan Somers <asom...@freebsd.org>
AuthorDate: 2025-06-11 21:26:48 +0000
Commit: Alan Somers <asom...@freebsd.org>
CommitDate: 2025-08-05 22:53:05 +0000
fusefs: don't fake the mountpoint's stat info before FUSE_INIT completes
Ever since the first GSoC contribution, fusefs has had a curious
behavior. If the daemon hasn't finished responding to FUSE_INIT,
fuse_vnop_getattr would reply to VOP_GETATTR requests for the mountpoint
by returning all zeros. I don't know why. It isn't necessary for
unmounting, even if the daemon is dead.
Delete that behavior. Now VOP_GETATTR for the mountpoint will wait for
the daemon to be ready, just like it will for any other vnode.
Reported by: Vassili Tchersky
Sponsored by: ConnectWise
Differential Revision: https://reviews.freebsd.org/D50800
---
sys/fs/fuse/fuse_vnops.c | 34 ++++++-------------
tests/sys/fs/fusefs/pre-init.cc | 72 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 81 insertions(+), 25 deletions(-)
diff --git a/sys/fs/fuse/fuse_vnops.c b/sys/fs/fuse/fuse_vnops.c
index 32872e8f3f3a..b90ce60ec664 100644
--- a/sys/fs/fuse/fuse_vnops.c
+++ b/sys/fs/fuse/fuse_vnops.c
@@ -1219,36 +1219,20 @@ fuse_vnop_getattr(struct vop_getattr_args *ap)
struct vattr *vap = ap->a_vap;
struct ucred *cred = ap->a_cred;
struct thread *td = curthread;
-
int err = 0;
- int dataflags;
-
- dataflags = fuse_get_mpdata(vnode_mount(vp))->dataflags;
-
- /* Note that we are not bailing out on a dead file system just yet. */
- if (!(dataflags & FSESS_INITED)) {
- if (!vnode_isvroot(vp)) {
- fdata_set_dead(fuse_get_mpdata(vnode_mount(vp)));
- return (EXTERROR(ENOTCONN, "FUSE daemon is not "
- "initialized"));
- } else {
- goto fake;
- }
- }
err = fuse_internal_getattr(vp, vap, cred, td);
if (err == ENOTCONN && vnode_isvroot(vp)) {
- /* see comment in fuse_vfsop_statfs() */
- goto fake;
- } else {
- return err;
+ /*
+ * We want to seem a legitimate fs even if the daemon is dead,
+ * so that, eg., we can still do path based unmounting after
+ * the daemon dies.
+ */
+ err = 0;
+ bzero(vap, sizeof(*vap));
+ vap->va_type = vnode_vtype(vp);
}
-
-fake:
- bzero(vap, sizeof(*vap));
- vap->va_type = vnode_vtype(vp);
-
- return 0;
+ return err;
}
/*
diff --git a/tests/sys/fs/fusefs/pre-init.cc b/tests/sys/fs/fusefs/pre-init.cc
index e990d3cafffa..2d3257500304 100644
--- a/tests/sys/fs/fusefs/pre-init.cc
+++ b/tests/sys/fs/fusefs/pre-init.cc
@@ -44,12 +44,26 @@ using namespace testing;
/* Tests for behavior that happens before the server responds to FUSE_INIT */
class PreInit: public FuseTest {
+public:
void SetUp() {
m_no_auto_init = true;
FuseTest::SetUp();
}
};
+/*
+ * Tests for behavior that happens before the server responds to FUSE_INIT,
+ * parameterized on default_permissions
+ */
+class PreInitP: public PreInit,
+ public WithParamInterface<bool>
+{
+void SetUp() {
+ m_default_permissions = GetParam();
+ PreInit::SetUp();
+}
+};
+
static void* unmount1(void* arg __unused) {
ssize_t r;
@@ -152,3 +166,61 @@ TEST_F(PreInit, signal_during_unmount_before_init)
sem_post(&sem0);
m_mock->join_daemon();
}
+
+/*
+ * If some process attempts VOP_GETATTR for the mountpoint before init is
+ * complete, fusefs should wait, just like it does for other VOPs.
+ *
+ * To verify that fuse_vnop_getattr does indeed wait for FUSE_INIT to complete,
+ * invoke the test like this:
+ *
+> sudo cpuset -c -l 0 dtrace -i 'fbt:fusefs:fuse_internal_init_callback:' -i
'fbt:fusefs:fuse_vnop_getattr:' -c "./pre-init
--gtest_filter=PI/PreInitP.getattr_before_init/0"
+...
+dtrace: pid 4224 has exited
+CPU ID FUNCTION:NAME
+ 0 68670 fuse_vnop_getattr:entry
+ 0 68893 fuse_internal_init_callback:entry
+ 0 68894 fuse_internal_init_callback:return
+ 0 68671 fuse_vnop_getattr:return
+ *
+ * Note that fuse_vnop_getattr was entered first, but exitted last.
+ */
+TEST_P(PreInitP, getattr_before_init)
+{
+ struct stat sb;
+ nlink_t nlink = 12345;
+
+ EXPECT_CALL(*m_mock, process(
+ ResultOf([=](auto in) {
+ return (in.header.opcode == FUSE_INIT);
+ }, Eq(true)),
+ _)
+ ).WillOnce(Invoke(ReturnImmediate([&](auto in, auto& out) {
+ SET_OUT_HEADER_LEN(out, init);
+ out.body.init.major = FUSE_KERNEL_VERSION;
+ out.body.init.minor = FUSE_KERNEL_MINOR_VERSION;
+ out.body.init.flags = in.body.init.flags & m_init_flags;
+ out.body.init.max_write = m_maxwrite;
+ out.body.init.max_readahead = m_maxreadahead;
+ out.body.init.time_gran = m_time_gran;
+ nap(); /* Allow stat() to run first */
+ })));
+ EXPECT_CALL(*m_mock, process(
+ ResultOf([=](auto in) {
+ return (in.header.opcode == FUSE_GETATTR &&
+ in.header.nodeid == FUSE_ROOT_ID);
+ }, Eq(true)),
+ _)
+ ).WillOnce(Invoke(ReturnImmediate([=](auto& in, auto& out) {
+ SET_OUT_HEADER_LEN(out, attr);
+ out.body.attr.attr.ino = in.header.nodeid;
+ out.body.attr.attr.mode = S_IFDIR | 0644;
+ out.body.attr.attr.nlink = nlink;
+ out.body.attr.attr_valid = UINT64_MAX;
+ })));
+
+ EXPECT_EQ(0, stat("mountpoint", &sb));
+ EXPECT_EQ(nlink, sb.st_nlink);
+}
+
+INSTANTIATE_TEST_SUITE_P(PI, PreInitP, Bool());
