Messages in this thread |  | | Date | Tue, 15 May 2001 11:04:30 +0100 | From | Anton Altaparmakov <> | Subject | Re: Getting FS access events |
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At 08:13 15/05/01, Linus Torvalds wrote: >On Tue, 15 May 2001, Richard Gooch wrote: > > So what happens if I dd from the block device and also from a file on > > the mounted FS, where that file overlaps the bnums I dd'ed? Do we get > > two copies in the page cache? One for the block device access, and one > > for the file access? > >Yup. And never the two shall meet. > >Why should they? Why would you ever do something like that, or care about >the fact?
They shouldn't, but maybe some stupid utility or a typo will do it creating two incoherent copies of the same block on the device. -> Bad Things can happen.
Can't we simply stop people from doing it by say having mount lock the device from further opens (and vice versa of course, doing a "dd" should result in lock of device preventing a mount during the duration of "dd"). - Wouldn't this be a good thing, guaranteeing that problems cannot happen while not incurring any overhead except on device open/close? Or is this a matter of "give the user enough rope"? - If proper rw locking is implemented it could allow simultaneous -o ro mount with a dd from the device but do exclusive write locking, for example, for maximum flexibility.
Just my 2p.
Anton
-- Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @) Linux NTFS Maintainer / WWW: http://sourceforge.net/projects/linux-ntfs/ ICQ: 8561279 / WWW: http://www-stu.christs.cam.ac.uk/~aia21/
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