Messages in this thread | | | Date | Fri, 3 Sep 2004 17:57:28 +0400 | From | Andrey Savochkin <> | Subject | Re: EXT3: problem with copy_from_user inside a transaction |
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On Fri, Sep 03, 2004 at 08:06:20AM -0400, Chris Mason wrote: > On Fri, 2004-09-03 at 08:35, Andrea Arcangeli wrote: > > On Fri, Sep 03, 2004 at 03:05:21PM +0400, Andrey Savochkin wrote: > > > > > > filemap_copy_from_user() between prepare_write() and commit_write() > > > appears to be a problem for ext3. > > > > And reiserv3, and maybe the other journaled filesystems. > > > yes, Chris is working on it for a few months. > > > Working is a generous term, I've somewhat been waiting for a better > solution to pop into my head. In the end, I think all we can do is not > allow filesystems to take locks (or implicit locks like starting a > transaction) inside the prepare_write call. > > This would mean that all the work is done during the commit_write > stage. The trick is that we would have to handle -ENOSPC since we might > not know we've run out of room until after the data has been copied from > userland.
What is the problem -ENOSPC? Do you think about the problem of the page existing before this write, it's content overwritten, but the filesystem being unable to commit that write because it needs more space?
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