Messages in this thread |  | | From | David Howells <> | Subject | Re: [GIT PULL] afs: Fixes | Date | Sat, 25 Nov 2017 22:35:43 +0000 |
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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?
> (b) can cause some really nasty latency issues
True, but I think the most common case is a file being opened, written start to finish and then closed. Actually, the worst-handled thing I've seen is a shell script appending a bunch of things to a file because ->flush() syncs the file each time it is closed:-/
What would you recommend instead? I'm currently trying and keep track of what needs to be written so that I only write what's changed to the server, rather than writing only whole pages.
David
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