On Wed 08-08-18 10:26:36, Dave Jiang wrote:
> This patch is the duplicate of ross's fix for ext4 for xfs.
> 
> If the refcount of a page is lowered between the time that it is returned
> by dax_busy_page() and when the refcount is again checked in
> xfs_break_layouts() => ___wait_var_event(), the waiting function
> xfs_wait_dax_page() will never be called.  This means that
> xfs_break_layouts() will still have 'retry' set to false, so we'll stop
> looping and never check the refcount of other pages in this inode.
> 
> Instead, always continue looping as long as dax_layout_busy_page() gives us
> a page which it found with an elevated refcount.
> 
> Signed-off-by: Dave Jiang <[email protected]>

I think I gave you my reviewed-by tag already for the previous version. But
here it is again:

Reviewed-by: Jan Kara <[email protected]>

                                                                Honza

> ---
> 
> v2:
> - Rename parameter from did_unlock to retry (Jan) 
> 
>  fs/xfs/xfs_file.c |    9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index a3e7767a5715..cd6f0d8c4922 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -721,12 +721,10 @@ xfs_file_write_iter(
>  
>  static void
>  xfs_wait_dax_page(
> -     struct inode            *inode,
> -     bool                    *did_unlock)
> +     struct inode            *inode)
>  {
>       struct xfs_inode        *ip = XFS_I(inode);
>  
> -     *did_unlock = true;
>       xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
>       schedule();
>       xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
> @@ -736,7 +734,7 @@ static int
>  xfs_break_dax_layouts(
>       struct inode            *inode,
>       uint                    iolock,
> -     bool                    *did_unlock)
> +     bool                    *retry)
>  {
>       struct page             *page;
>  
> @@ -746,9 +744,10 @@ xfs_break_dax_layouts(
>       if (!page)
>               return 0;
>  
> +     *retry = true;
>       return ___wait_var_event(&page->_refcount,
>                       atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
> -                     0, 0, xfs_wait_dax_page(inode, did_unlock));
> +                     0, 0, xfs_wait_dax_page(inode));
>  }
>  
>  int
> 
-- 
Jan Kara <[email protected]>
SUSE Labs, CR
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