Fix example/fix-notify_inval_inode.c (#908)

Similar issue as fixed in commit
3c7ba570 "examples/notify_store_retrieve: Add a clean shutdown".
Basically a clean shutdown was missing, but even with clean
shutdown it does not work, as kernel side releases inodes before
sending FUSE_DESTROY - the intervaled thread then gets
-ENOENT.

Co-authored-by: Bernd Schubert <bschubert@ddn.com>

1 files changed, 27 insertions, 5 deletions

diff --git a/example/notify_inval_inode.c b/example/notify_inval_inode.c
index b3b50aa..b1fb8f7 100644
--- a/example/notify_inval_inode.c
+++ b/example/notify_inval_inode.c
@@ -71,6 +71,8 @@
 #include <stddef.h>
 #include <unistd.h>
 #include <pthread.h>
+#include <stdbool.h>
+#include <stdatomic.h>
 
 /* We can't actually tell the kernel that there is no
    timeout, so we just send a big value */
@@ -82,6 +84,7 @@
 static char file_contents[MAX_STR_LEN];
 static int lookup_cnt = 0;
 static size_t file_size;
+static _Atomic bool is_stop = false;
 
 /* Command line parsing */
 struct options {
@@ -120,6 +123,13 @@ static int tfs_stat(fuse_ino_t ino, struct stat *stbuf) {
     return 0;
 }
 
+static void tfs_destroy(void *userarg)
+{
+    (void)userarg;
+
+    is_stop = true;
+}
+
 static void tfs_lookup(fuse_req_t req, fuse_ino_t parent,
                        const char *name) {
     struct fuse_entry_param e;
@@ -240,6 +250,7 @@ static void tfs_read(fuse_req_t req, fuse_ino_t ino, size_t size,
 }
 
 static const struct fuse_lowlevel_ops tfs_oper = {
+    .destroy    = tfs_destroy,
     .lookup	= tfs_lookup,
     .getattr	= tfs_getattr,
     .readdir	= tfs_readdir,
@@ -263,13 +274,24 @@ static void update_fs(void) {
 static void* update_fs_loop(void *data) {
     struct fuse_session *se = (struct fuse_session*) data;
 
-    while(1) {
+    while(!is_stop) {
         update_fs();
         if (!options.no_notify && lookup_cnt) {
-            /* Only send notification if the kernel
-               is aware of the inode */
-            assert(fuse_lowlevel_notify_inval_inode
-                   (se, FILE_INO, 0, 0) == 0);
+            /* Only send notification if the kernel is aware of the inode */
+
+            /* Some errors (ENOENT, EBADFD, ENODEV) have to be accepted as the
+             * might come up during umount, when kernel side already releases
+             * all inodes, but does not send FUSE_DESTROY yet.
+             */
+            int ret =
+                fuse_lowlevel_notify_inval_inode(se, FILE_INO, 0, 0);
+            if ((ret != 0 && !is_stop) &&
+                 ret != -ENOENT && ret != -EBADFD && ret != -ENODEV) {
+                fprintf(stderr,
+                        "ERROR: fuse_lowlevel_notify_store() failed with %s (%d)\n",
+                        strerror(-ret), -ret);
+                abort();
+            }
         }
         sleep(options.update_interval);
     }