Messages in this thread | | | Date | Wed, 27 Mar 2013 17:45:06 +0000 | From | Al Viro <> | Subject | Re: Yet another pipe related oops. |
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On Wed, Mar 27, 2013 at 09:33:35AM -0700, Linus Torvalds wrote:
> Applied. > > Do we actually have files with NULL f_ops pointers? Should we? What > could we possibly do with a file descriptor that doesn't have any > fops?
We shouldn't, at least not for something that has been successfully opened. I've a patch series cleaning that up a bit in the local queue; will check for bitrot and throw into for-next.
Another thing that is a definite for-next fodder - we really have no reason to put anything non-regular or opened not for write into ->s_files. And since read-only opens outnumber write-only/read-write ones by far (two orders of magnitude for something like kernel build), that gives a nice reduction of files_lglock accesses. OTOH, the only remaining user of those lists is forced remount to read-only, and I'm not at all sure we wouldn't be better off by leaving those opened files alone and just teaching file_start_write() to fail with EROFS on such fs. Then we could get rid of files_lglock and ->s_files completely...
> Also, perhaps we should do something more akin to what we do for > dentry functions where we validate them on registration, and we could > fix up or validate read/write pointers, with semantics something like > > if (!fop->write) > fop->write = fop->aio_write ? do_sync_write : EINVAL_write; > if (!fop->read) > fop->read = fop->aio_read ? do_sync_read : EINVAL_read; > > kind of things?
As it is, file_operations instances are const, and it's a good idea, IMO...
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