Messages in this thread | | | Date | Sun, 26 Nov 2017 09:48:06 +1100 | From | Dave Chinner <> | Subject | Re: [GIT PULL] afs: Fixes |
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On Sat, Nov 25, 2017 at 10:35:43PM +0000, David Howells wrote: > Linus Torvalds <torvalds@linux-foundation.org> wrote: > > > So I see in the commit message why afs needs to do this, but it's > > worth pointing out that it's > > > > (a) impossible to avoid the "inconsistent data" case for writable mmap'ed > > pages > > Doesn't clear_page_dirty_for_io() write-protect the PTE for the page to be > written out, in which case ->page_mkwrite() will get called again before the > page is redirtied?
Yes, but page_mkwrite will only block on writeback in progress is if the backing device says it needs stable pages. See wait_for_stable_page(). e.g. stable pages are required if RAID is in use, otherwise modification during IO can result in broken on-disk parity/mirroring....
Cheers,
Dave. -- Dave Chinner david@fromorbit.com
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