Messages in this thread | | | Date | Fri, 04 Oct 2002 13:29:40 -0700 | From | Andrew Morton <> | Subject | Re: 2.5 O)DIRECT problem |
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Steve Lord wrote: > > Hi Andrew, > > I ran into a problem with 2.5's O_DIRECT read path, > > generic_file_direct_IO usually ends up in generic_direct_IO > this does bounds checking on the I/O and then flushes any > cached data. > > Once we return to generic_file_direct_IO we unconditionally > call invalidate_inode_pages2 if there are any cached pages. > > If we make a non-aligned O_DIRECT read call, the end result is we > call invalidate_inode_pages2, but we do not do the filemap_fdatawrite, > filemap_fdatawait calls. End result is we throw the buffered data away.
Well you could always switch to Linus' current BK tree, in which invalidate_inode_pages2() is a no-op (whoops).
> Either the flush needs to happen before the bounds checks, or the > invalidate should only be done on a successful write. It looks > pretty hard to detect the latter case with the current structure, > we can get EINVAL from the bounds check and possibly from an > aligned, but invalid memory address being passed in.
Yes I agree; let's just do the sync before any checks.
I think it should be moved into generic_file_direct_IO(), because that's the place where the invalidation happens, yes? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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