Re: [PATCH] fuse: honour max_read and max_write in direct_io mode
From: Al Viro
Date: Wed Sep 24 2014 - 15:02:03 EST
On Wed, Sep 24, 2014 at 05:09:11PM +0200, Miklos Szeredi wrote:
> From: Miklos Szeredi <mszeredi@xxxxxxx>
>
> The third argument of fuse_get_user_pages() "nbytesp" refers to the number of
> bytes a caller asked to pack into fuse request. This value may be lesser
> than capacity of fuse request or iov_iter. So fuse_get_user_pages() must
> ensure that *nbytesp won't grow.
>
> Now, when helper iov_iter_get_pages() performs all hard work of extracting
> pages from iov_iter, it can be done by passing properly calculated
> "maxsize" to the helper.
>
> The other caller of iov_iter_get_pages() (dio_refill_pages()) doesn't need
> this capability, so pass LONG_MAX as the maxsize argument here.
>
> Fixes: c9c37e2e6378 ("fuse: switch to iov_iter_get_pages()")
> Reported-by: Werner Baumann <werner.baumann@xxxxxxxxxxxxx>
> Tested-by: Maxim Patlasov <mpatlasov@xxxxxxxxxxxxx>
> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
Applied, will be in tonight pull request.
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