On Fri, 07 Feb 2025, Kent Overstreet wrote: > On Fri, Feb 07, 2025 at 05:34:23PM +1100, NeilBrown wrote: > > On Fri, 07 Feb 2025, Kent Overstreet wrote: > > > On Fri, Feb 07, 2025 at 03:53:52PM +1100, NeilBrown wrote: > > > > Do you think there could be a problem with changing the error returned > > > > in this circumstance? i.e. if you try to destroy a subvolume with a > > > > non-existant name on a different filesystem could getting -ENOENT > > > > instead of -EXDEV be noticed? > > > > > > -EXDEV is the standard error code for "we're crossing a filesystem > > > boundary and we can't or aren't supposed to be", so no, let's not change > > > that. > > > > > > > OK. As bcachefs is the only user of user_path_locked_at() it shouldn't > > be too hard. > > Hang on, why does that require keeping user_path_locked_at()? Just > compare i_sb... > I changed user_path_locked_at() to not return a dentry at all when the full path couldn't be found. If there is no dentry, then there is no ->d_sb. (if there was an ->i_sb, there would be an inode and this all wouldn't be an issue). To recap: the difference happens if the path DOESN'T exist but the parent DOES exist on a DIFFERENT filesystem. It is very much a corner case and the error code shouldn't matter. But I had to ask... NeilBrown
