fuse: don't block in fuse_get_dev() for non-sync_init case

Commit a8dd5f1b73bc ("fuse: create fuse_dev on /dev/fuse open instead of
mount") changed behavior so that fuse_get_dev() now unconditionally
blocks waiting for a connection, even in the case where sync_init was
not set. Previously, non-sync_init opens returned -EPERM immediately.

Restore the previous behavior of returning -EPERM.

Fixes: a8dd5f1b73bc ("fuse: create fuse_dev on /dev/fuse open instead of mount")
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/all/3c9f8396-41f4-4c88-b883-34bede72b427@sirena.org.uk/
Cc: <stable@vger.kernel.org>
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Tested-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 5dda7080f4a909740cd3dbf804a5260e7493b512..05b6d15afe61e3fbc9c7d8df8fbf013abff809ef 100644 (file)
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1562,9 +1562,15 @@ struct fuse_dev *fuse_get_dev(struct file *file)
        struct fuse_dev *fud = fuse_file_to_fud(file);
        int err;
 
-       err = wait_event_interruptible(fuse_dev_waitq, fuse_dev_fc_get(fud) != NULL);
-       if (err)
-               return ERR_PTR(err);
+       if (unlikely(!fuse_dev_fc_get(fud))) {
+               /* only block waiting for mount if sync init was requested */
+               if (!fud->sync_init)
+                       return ERR_PTR(-EPERM);
+
+               err = wait_event_interruptible(fuse_dev_waitq, fuse_dev_fc_get(fud) != NULL);
+               if (err)
+                       return ERR_PTR(err);
+       }
 
        return fud;
 }