Messages in this thread | | | Date | Wed, 17 Dec 2014 00:06:10 -0800 | From | Christoph Hellwig <> | Subject | Re: [PATCH 2/8] swap: lock i_mutex for swap_writepage direct_IO |
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On Tue, Dec 16, 2014 at 12:56:24AM -0800, Omar Sandoval wrote: > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1728,6 +1728,9 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) > } > > if (mapping->a_ops->swap_activate) { > + if (!mapping->a_ops->direct_IO) > + return -EINVAL; > + swap_file->f_flags |= O_DIRECT; > ret = mapping->a_ops->swap_activate(sis, swap_file, span); > if (!ret) { > sis->flags |= SWP_FILE;
This needs to hold swap_file->f_lock, but otherwise looks good.
> This seems to be more or less equivalent to doing a fcntl(F_SETFL) to > add the O_DIRECT flag to swap_file (which is a struct file *). Swapoff > calls filp_close on swap_file, so I don't see why it's necessary to > clear the flag.
filp_lose doesn't nessecarily destroy the file structure, there might be other reference to it, e.g. from dup() or descriptor passing.
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