On Wed, Sep 23, 2020 at 07:46:36PM +0300, Alexander Mikhalitsyn wrote: > During execution of vfs_fsconfig_locked function we can get ERESTARTNOINTR > error (or other interrupt error). But we changing fs context fc->phase > field to transient states and our entry fc->phase checks in switch cases > (see FS_CONTEXT_CREATE_PARAMS, FS_CONTEXT_RECONF_PARAMS) will always fail > after syscall restart which will lead to returning -EBUSY to the userspace. > > The idea of the fix is to save entry-time fs_context phase field value and > recover fc->phase value to the original one before exiting with > "interrupt error" (ERESTARTNOINTR or similar). If you have e.g. vfs_create_tree() fail in the middle of ->get_tree(), the only thing you can do to that thing is to discard it. The state is *NOT* required to be recoverable after a failure exit - quite a bit of config might've been consumed and freed by that point. CREATE and RECONFIGURE are simply not restartable.
