linux-ext4 - Re: [PATCH] ext4: move_extent explicitly invalidate page buffers

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Date:	Thu, 23 Oct 2014 17:03:31 +0400
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	linux-ext4@...r.kernel.org
Cc:	tytso@....edu, wangxg.fnst@...fujitsu.com
Subject: Re: [PATCH] ext4: move_extent explicitly invalidate page buffers

Dmitry Monakhov <dmonakhov@...nvz.org> writes:

> In hard core test-cases such as ext4/301, ext4/302 some bh may
> becomes dirty so try_to_release_page() will fail and result in
> false positive EBUSY failures. We can easily fix that by
> explicit ->invalidatepage() after we holds page which is locked
> and uptodate.
Sorry. This patch is not correct. Please ignore it.
>
> Tested-by: Xiaoguang Wang<wangxg.fnst@...fujitsu.com>
> Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
> ---
>  fs/ext4/move_extent.c |   10 +++++++---
>  1 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
> index c2b2b02..76c45b6 100644
> --- a/fs/ext4/move_extent.c
> +++ b/fs/ext4/move_extent.c
> @@ -348,8 +348,9 @@ again:
>  		     !try_to_release_page(pagep[0], 0)) ||
>  		    (page_has_private(pagep[1]) &&
>  		     !try_to_release_page(pagep[1], 0))) {
> -			*err = -EBUSY;
> -			goto drop_data_sem;
> +			/* One of buffers is busy, fall back data copy */
> +			ext4_double_up_write_data_sem(orig_inode, donor_inode);
> +			goto data_copy;
>  		}
>  		replaced_count = ext4_swap_extents(handle, orig_inode,
>  						   donor_inode, orig_blk_offset,
> @@ -360,12 +361,15 @@ again:
>  		goto unlock_pages;
>  	}
>  data_copy:
> -	*err = mext_page_mkuptodate(pagep[0], from, from + replaced_size);
> +	/* In order to drop all buffers we have to make page fully uptodate */
> +	*err = mext_page_mkuptodate(pagep[0], 0, PAGE_CACHE_SIZE);
>  	if (*err)
>  		goto unlock_pages;
>  
>  	/* At this point all buffers in range are uptodate, old mapping layout
>  	 * is no longer required, try to drop it now. */
> +	do_invalidatepage(pagep[0], 0, PAGE_CACHE_SIZE);
> +	do_invalidatepage(pagep[1], 0, PAGE_CACHE_SIZE);
>  	if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) ||
>  	    (page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) {
>  		*err = -EBUSY;
> -- 
> 1.7.1
>
> --
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