On Tue, Feb 26, 2019 at 12:07:37PM +0800, Qu Wenruo wrote:
>
>
> On 2019/2/25 下午11:46, Josef Bacik wrote:
> > On Mon, Feb 25, 2019 at 01:26:57PM +0100, David Sterba wrote:
> >> On Mon, Feb 25, 2019 at 08:17:52PM +0800, Qu Wenruo wrote:
> >>>
> >>>
> >>> On 2019/2/25 下午8:15, David Sterba wrote:
> >>>> On Mon, Feb 25, 2019 at 01:50:43PM +0800, Qu Wenruo wrote:
> >>>>> All users of extent_io_tree::private_data are expecting struct inode*.
> >>>>> So just use struct inode* to replace extent_io_tree::private_data, and
> >>>>> this should provide better type check.
> >>>>>
> >>>>> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
> >>>>> struct extent_io_tree {
> >>>>> struct rb_root state;
> >>>>> - void *private_data;
> >>>>> + struct inode *inode;
> >>>>> u64 dirty_bytes;
> >>>>> int track_uptodate;
> >>>>> spinlock_t lock;
> >>>>
> >>>> So this is effectively reverting c6100a4b4e3d1650deafd ("Btrfs: replace
> >>>> tree->mapping with tree->private_data"),
> >>>
> >>> That commit message doesn't explain why this is needed for btree_inode
> >>> removal.
> >>>
> >>> Any idea what the extra type would be used in that case?
> >>
> >> I don't know, Josef in CC to answer that.
> >
> > Yeah there's a mapping tree thing I make to keep track of the metadata, it holds
> > the radix tree for the eb's and a bunch of other stuff. This needs to stay a
> > void *. Thanks,
>
> Then what about an union here?
>
> BTW, for no btree_inode case, how do we distinguish regular inode
> pointer with yours? An extra member?
>
We don't have to, the only place the inode is used is when doing the callbacks.
The callbacks are implementation specific, so the btree extent_io callbacks know
that the void *private_data is their struct btrfs_eb_info, and the inode ones
know it's their struct inode *. Thanks,
Josef
