From f6e02ff4a0d7023896e16b08bdaf422c49d0dc8f Mon Sep 17 00:00:00 2001
From: Casey Bodley <cbodley@citi.umich.edu>
Date: Fri, 4 May 2012 11:32:31 -0400
Subject: [PATCH] driver: make mount upcalls for shared mounts

even if CreateVNetRoot() finds an existing compatible mount, make a MOUNT upcall and pass that session to the daemon.  the daemon can avoid creating a new root/client/seession, but still has a chance to verify the mount path with LOOKUPs and fetch fs attributes for the new VNetRoot

when the daemon is given an existing root, handle_mount() avoids any extra reference counting on it.  while we can make multiple MOUNT upcalls on a shared mount, we'll still only send the one UNMOUNT upcall on FinalizeNetRoot()

Signed-off-by: Casey Bodley <cbodley@citi.umich.edu>
---
 daemon/mount.c     | 35 ++++++++++++++++++++++-------------
 sys/nfs41_driver.c | 32 +++++++++++++++-----------------
 2 files changed, 37 insertions(+), 30 deletions(-)

diff --git a/daemon/mount.c b/daemon/mount.c
index 8c4efe8..55345f6 100644
--- a/daemon/mount.c
+++ b/daemon/mount.c
@@ -69,17 +69,24 @@ static int handle_mount(nfs41_upcall *upcall)
         eprintf("nfs41_server_resolve() failed with %d\n", status);
         goto out;
     }
-    // create root
-    status = nfs41_root_create(args->hostname, args->sec_flavor,
-        args->wsize + WRITE_OVERHEAD, args->rsize + READ_OVERHEAD, &root);
-    if (status) {
-        eprintf("nfs41_root_create() failed %d\n", status);
-        goto out;
-    }
-    // add a mount
-    root->uid = upcall->uid;
-    root->gid = upcall->gid;
 
+    if (upcall->root_ref != INVALID_HANDLE_VALUE) {
+        /* use an existing root from a previous mount, but don't take an
+         * extra reference; we'll only get one UNMOUNT upcall for each root */
+        root = upcall->root_ref;
+    } else {
+        // create root
+        status = nfs41_root_create(args->hostname, args->sec_flavor,
+            args->wsize + WRITE_OVERHEAD, args->rsize + READ_OVERHEAD, &root);
+        if (status) {
+            eprintf("nfs41_root_create() failed %d\n", status);
+            goto out;
+        }
+        root->uid = upcall->uid;
+        root->gid = upcall->gid;
+    }
+
+    // find or create the client/session
     status = nfs41_root_mount_addrs(root, &addrs, 0, 0, &client);
     if (status) {
         eprintf("nfs41_root_mount_addrs() failed with %d\n", status);
@@ -89,7 +96,7 @@ static int handle_mount(nfs41_upcall *upcall)
     // make a copy of the path for nfs41_lookup()
     InitializeSRWLock(&path.lock);
     if (FAILED(StringCchCopyA(path.path, NFS41_MAX_PATH_LEN, args->path))) {
-        status = ERROR_BUFFER_OVERFLOW;
+        status = ERROR_FILENAME_EXCED_RANGE;
         goto out_err;
     }
     path.len = (unsigned short)strlen(path.path);
@@ -105,14 +112,16 @@ static int handle_mount(nfs41_upcall *upcall)
 
     nfs41_superblock_fs_attributes(file.fh.superblock, &args->FsAttrs);
 
+    if (upcall->root_ref == INVALID_HANDLE_VALUE)
+        nfs41_root_ref(root);
     upcall->root_ref = root;
-    nfs41_root_ref(upcall->root_ref);
     args->lease_time = client->session->lease_time;
 out:
     return status;
 
 out_err:
-    nfs41_root_deref(root);
+    if (upcall->root_ref == INVALID_HANDLE_VALUE)
+        nfs41_root_deref(root);
     goto out;
 }
 
diff --git a/sys/nfs41_driver.c b/sys/nfs41_driver.c
index 641cbfd..392247b 100644
--- a/sys/nfs41_driver.c
+++ b/sys/nfs41_driver.c
@@ -2619,7 +2619,7 @@ NTSTATUS nfs41_mount(
     DbgP("Server Name %wZ Mount Point %wZ SecFlavor %d\n",
         &config->SrvName, &config->MntPt, sec_flavor);
 #endif
-    status = nfs41_UpcallCreate(NFS41_MOUNT, NULL, INVALID_HANDLE_VALUE,
+    status = nfs41_UpcallCreate(NFS41_MOUNT, NULL, *session,
         INVALID_HANDLE_VALUE, *version, &config->MntPt, &entry);
     if (status) goto out;
 
@@ -3050,23 +3050,21 @@ NTSTATUS nfs41_CreateVNetRoot(
 #endif
     }
 
-    if (!found_existing_mount || !found_matching_flavor) {
-        /* send the mount upcall */
-        status = nfs41_mount(Config, pVNetRootContext->sec_flavor,
-            &pVNetRootContext->session, &nfs41d_version,
-            &pVNetRootContext->FsAttrs);
-        if (status != STATUS_SUCCESS) {
-            if (!found_existing_mount && 
-                    IsListEmpty(&pNetRootContext->mounts.head)) {
-                pNetRootContext->mounts_init = FALSE;
-                pVNetRootContext->session = INVALID_HANDLE_VALUE;
-            }
-            goto out_free;
+    /* send the mount upcall */
+    status = nfs41_mount(Config, pVNetRootContext->sec_flavor,
+        &pVNetRootContext->session, &nfs41d_version,
+        &pVNetRootContext->FsAttrs);
+    if (status != STATUS_SUCCESS) {
+        if (!found_existing_mount &&
+                IsListEmpty(&pNetRootContext->mounts.head)) {
+            pNetRootContext->mounts_init = FALSE;
         }
-        pVNetRootContext->timeout = Config->timeout;
-        RtlCopyMemory(&pNetRootContext->FsAttrs, &pVNetRootContext->FsAttrs,
-            sizeof(pVNetRootContext->FsAttrs));
-    } 
+        pVNetRootContext->session = INVALID_HANDLE_VALUE;
+        goto out_free;
+    }
+    pVNetRootContext->timeout = Config->timeout;
+    RtlCopyMemory(&pNetRootContext->FsAttrs, &pVNetRootContext->FsAttrs,
+        sizeof(pVNetRootContext->FsAttrs));
 
     if (!found_existing_mount) {
         /* create a new mount entry and add it to the list */