emacs-28 5946370: Check, whether an FUSE mount has been broken in Tramp

[Michael Albinus]

branch: emacs-28
commit 5946370cd1d6728f2edd071fa8befc88fd0bd7a7
Author: Michael Albinus <michael.albinus@gmx.de>
Commit: Michael Albinus <michael.albinus@gmx.de>

    Check, whether an FUSE mount has been broken in Tramp
    
    * lisp/net/tramp-fuse.el (tramp-fuse-mount-timeout): New defconst.
    (tramp-fuse-mounted-p): Use it.  Check for a file property instead
    of a connection property.
    (tramp-fuse-unmount): Dito.
    
    * lisp/net/tramp-sshfs.el (tramp-sshfs-maybe-open-connection):
    Do not trust existence of a process, whether the volume is mounted.
---
 lisp/net/tramp-fuse.el  | 25 ++++++++++++++++---------
 lisp/net/tramp-sshfs.el | 50 ++++++++++++++++++++++++-------------------------
 2 files changed, 41 insertions(+), 34 deletions(-)

diff --git a/lisp/net/tramp-fuse.el b/lisp/net/tramp-fuse.el
index d2bac2d..c359082 100644
--- a/lisp/net/tramp-fuse.el
+++ b/lisp/net/tramp-fuse.el
@@ -156,19 +156,27 @@
        (tramp-file-name-host-port vec))
        tramp-compat-temporary-file-directory)))
 
+(defconst tramp-fuse-mount-timeout
+  (eval (car (get 'remote-file-name-inhibit-cache 'standard-value)) t)
+  "Time period to check whether the mount point still exists.
+It has the same meaning as `remote-file-name-inhibit-cache'.")
+
 (defun tramp-fuse-mounted-p (vec)
   "Check, whether fuse volume determined by VEC is mounted."
-  (when (tramp-get-connection-process vec)
-    ;; We cannot use `with-connection-property', because we don't want
-    ;; to cache a nil result.
-    (or (tramp-get-connection-property
-         (tramp-get-connection-process vec) "mounted" nil)
+  ;; Remember the mount status by using a file property on "/",
+  ;; instead of using a connection property, because a file property
+  ;; has a timeout.  Having a timeout lets us regularly recheck the
+  ;; mount status, as requested by `tramp-fuse-mount-timeout'.  We
+  ;; cannot use `with-tramp-file-property', because we don't want to
+  ;; cache a nil result.
+  (let ((remote-file-name-inhibit-cache tramp-fuse-mount-timeout))
+    (or (tramp-get-file-property vec "/" "mounted" nil)
         (let* ((default-directory tramp-compat-temporary-file-directory)
                (command (format "mount -t fuse.%s" (tramp-file-name-method 
vec)))
               (mount (shell-command-to-string command)))
           (tramp-message vec 6 "%s\n%s" command mount)
-          (tramp-set-connection-property
-           (tramp-get-connection-process vec) "mounted"
+          (tramp-set-file-property
+          vec "/" "mounted"
            (when (string-match
                  (format
                    "^\\(%s\\)\\s-" (regexp-quote (tramp-fuse-mount-spec vec)))
@@ -191,8 +199,7 @@
         (mount-point (tramp-fuse-mount-point vec))
          (command (format "%s -u %s" (tramp-fuse-get-fusermount) mount-point)))
     (tramp-message vec 6 "%s\n%s" command (shell-command-to-string command))
-    (tramp-flush-connection-property
-     (tramp-get-connection-process vec) "mounted")
+    (tramp-flush-file-property vec "/" "mounted")
     (setq tramp-fuse-mount-points
          (delete (tramp-file-name-unify vec) tramp-fuse-mount-points))
     ;; Give the caches a chance to expire.
diff --git a/lisp/net/tramp-sshfs.el b/lisp/net/tramp-sshfs.el
index 2be0485..1bd4c5d 100644
--- a/lisp/net/tramp-sshfs.el
+++ b/lisp/net/tramp-sshfs.el
@@ -349,31 +349,31 @@ connection if a previous connection has died for some 
reason."
       (tramp-set-connection-property p "lock-pid" (truncate (time-to-seconds)))
 
       ;; Set connection-local variables.
-      (tramp-set-connection-local-variables vec)
-
-      ;; Create directory.
-      (unless (file-directory-p (tramp-fuse-mount-point vec))
-       (make-directory (tramp-fuse-mount-point vec) 'parents))
-
-      (unless
-         (or (tramp-fuse-mounted-p vec)
-             (with-temp-buffer
-               (zerop
-                (apply
-                 #'tramp-call-process
-                 vec tramp-sshfs-program nil t nil
-                 (tramp-fuse-mount-spec vec)
-                 (tramp-fuse-mount-point vec)
-                 (tramp-expand-args
-                  vec 'tramp-mount-args
-                  ?p (or (tramp-file-name-port vec) "")))))
-         (tramp-error
-          vec 'file-error "Error mounting %s" (tramp-fuse-mount-spec vec))))
-
-      ;; Mark it as connected.
-      (add-to-list 'tramp-fuse-mount-points (tramp-file-name-unify vec))
-      (tramp-set-connection-property
-       (tramp-get-connection-process vec) "connected" t)))
+      (tramp-set-connection-local-variables vec)))
+
+  ;; Create directory.
+  (unless (file-directory-p (tramp-fuse-mount-point vec))
+    (make-directory (tramp-fuse-mount-point vec) 'parents))
+
+  (unless
+      (or (tramp-fuse-mounted-p vec)
+         (with-temp-buffer
+           (zerop
+            (apply
+             #'tramp-call-process
+             vec tramp-sshfs-program nil t nil
+             (tramp-fuse-mount-spec vec)
+             (tramp-fuse-mount-point vec)
+             (tramp-expand-args
+              vec 'tramp-mount-args
+              ?p (or (tramp-file-name-port vec) ""))))))
+    (tramp-error
+     vec 'file-error "Error mounting %s" (tramp-fuse-mount-spec vec)))
+
+  ;; Mark it as connected.
+  (add-to-list 'tramp-fuse-mount-points (tramp-file-name-unify vec))
+  (tramp-set-connection-property
+   (tramp-get-connection-process vec) "connected" t)
 
   ;; In `tramp-check-cached-permissions', the connection properties
   ;; "{uid,gid}-{integer,string}" are used.  We set them to proper values.