Christian Brauner <christian@xxxxxxxxxx> wrote: > So from reading the patch I got the impression that superblock mount > options passed via fsconfig() are passed as strings like "ro" and are > translated into approriate objects (e.g. flags etc.) by the kernel. I'm having second throughts about that - at least for "ro": that one is particularly problematic as it governs how source devices are opened. I'm kind of tempted to pass that as a flag to fsopen(). What I'd like to do in btrfs, ext4, etc. is open blockdevs as I get the parameters that enumerate them - but I have to hold the looked-up paths till the validate/get_tree stage so that I know the final ro/rw state before I can do the opening. > That seems like a future proof mechanism to extend mount options for > userspace without having to worry about exceeding any integer types in the > future. Maybe this would make sense for non-superblock options as well? I > can see that this is less performant that checking flags and string parsing > is a thing that is not particularly nice but it would be one option to solve > the running out of flags problem. Al disliked the idea of setting up a separate context to define the mount options. > > mount_setattr(int dfd, const char *path, unsigned int atflags, > > unsigned int attr_values, > > unsigned int attr_mask); > > If we go with the flag arguments wouldn't it make sense to use a larger > integer type? You can't - at least not directly through syscall args. They are 32-bit on a 32-bit system. > > where atflags can potentially include AT_RECURSIVE. > > Very much in favor of having this operate recursively! It gets complicated with propagation. David
