Re: [RFC PATCH] Btrfs: handle unaligned tail of data ranges more efficient

[Nikolay Borisov <nborisov@suse.com>]

On 25.08.2017 00:12, Timofey Titovets wrote:
> At now while switch page bits in data ranges
> we always hande +1 page, for cover case
> where end of data range is not page aligned
> 
> Let's handle that case more obvious and efficient
> Check end aligment directly and touch +1 page
> only then needed
> 
> Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
> ---
>  fs/btrfs/extent_io.c | 12 ++++++++++--
>  fs/btrfs/inode.c     |  6 +++++-
>  2 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index 98d85d2009f8..ccb66c1485e2 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -1360,7 +1360,11 @@ void extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end)
>  	unsigned long end_index = end >> PAGE_SHIFT;
>  	struct page *page;
> 
> -	while (index <= end_index) {
> +	/* Don't miss unaligned end */
> +	if (end%PAGE_SIZE > 0)
> +		end_index++;

if (!IS_ALIGNED(end, PAGE_SIZE)).



> +
> +	while (index < end_index) {
>  		page = find_get_page(inode->i_mapping, index);
>  		BUG_ON(!page); /* Pages should be in the extent_io_tree */
>  		clear_page_dirty_for_io(page);
> @@ -1375,7 +1379,11 @@ void extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end)
>  	unsigned long end_index = end >> PAGE_SHIFT;
>  	struct page *page;
> 
> -	while (index <= end_index) {
> +	/* Don't miss unaligned end */
> +	if (end%PAGE_SIZE > 0)
> +		end_index++;

ditto

> +
> +	while (index < end_index) {
>  		page = find_get_page(inode->i_mapping, index);
>  		BUG_ON(!page); /* Pages should be in the extent_io_tree */
>  		__set_page_dirty_nobuffers(page);
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index cb7779b08aaf..79feaea0fede 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -10745,7 +10745,11 @@ void btrfs_set_range_writeback(void *private_data, u64 start, u64 end)
>  	unsigned long end_index = end >> PAGE_SHIFT;
>  	struct page *page;
> 
> -	while (index <= end_index) {
> +	/* Don't miss unaligned end */
> +	if (end%PAGE_SIZE > 0)
> +		end_index++;
Ditto

> +
> +	while (index < end_index) {
>  		page = find_get_page(inode->i_mapping, index);
>  		ASSERT(page); /* Pages should be in the extent_io_tree */
>  		set_page_writeback(page);
> --
> 2.14.1
> --
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