On Thu, May 20, 2010 at 12:18 AM, Miao Xie <miaox@xxxxxxxxxxxxxx> wrote:
> From: Liu Bo <liubo2009@xxxxxxxxxxxxxx>
>
> If add_to_page_cache_lru() returns -EEXIST, it indicates the page
> that belongs to this page_index has been added and this readahead
> action can go on to next page.
>
> If add_to_page_cache_lru() returns -ENOMEM, it should break for
> no memory left.
>
> Signed-off-by: Liu Bo <liubo2009@xxxxxxxxxxxxxx>
> Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/compression.c | 19 ++++++++++++++++---
> 1 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
> index 1d54c53..1bd4d92 100644
> --- a/fs/btrfs/compression.c
> +++ b/fs/btrfs/compression.c
> @@ -480,10 +480,23 @@ static noinline int add_ra_bio_pages(struct inode *inode,
> if (!page)
> break;
>
> - if (add_to_page_cache_lru(page, mapping, page_index,
> - GFP_NOFS)) {
> + ret = add_to_page_cache_lru(page, mapping, page_index,
> + GFP_NOFS);
> + if (ret) {
> page_cache_release(page);
> - goto next;
> +
> + /*
> + * -EEXIST indicates the page has been added, so
> + * it can move on to next page.
> + */
> + if (ret == -EEXIST) {
> + misses++;
> + if (misses > 4)
> + break;
Shouldn't this use a pre-processor label instead of hard coding
compression sensitivity or readahead tuning? this way it'll be set in
one place.
> + goto next;
> + }
> +
> + break;
> }
>
> end = last_offset + PAGE_CACHE_SIZE - 1;
> --
> 1.6.5.2
>
> --
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