On Sat, Jun 25, 2022 at 06:39:52AM -0700, Christoph Hellwig wrote: > On Sat, Jun 25, 2022 at 02:29:09PM +0100, Al Viro wrote: > > I wouldn't bet on that - as it is, an ->open() instance can decide > > in some cases to clear FMODE_LSEEK, despite having file_operations > > with non-NULL ->llseek. > > The interesting cases here are nonseekable_open and stream_open, > and I don't see why we could not fix this up in the file_operations. What's the point, really? We can easily enforce "no FMODE_LSEEK ever observed on files with NULL ->llseek" (this series does that), so we can use that check alone in e.g. vfs_llseek() or dump_skip(). Sure, we are tight on bits in ->f_mode, but there's a better way to relieve that problem - split the field into "stuff that needs to be preserved all the way until __fput()" and the rest; the latter could sit next to ->f_iocb_flags, with no increase of struct file size. So if you are worried about FMODE_... space getting exhausted, that's better dealt with in a different way, IMO.
