On Tue, Oct 08, 2013 at 01:31:57PM -0400, Josef Bacik wrote:
> Liu fixed part of this problem and unfortunately I steered him in slightly the
> wrong direction and so didn't completely fix the problem. The problem is we
> limit the size of the delalloc range we are looking for to max bytes and then we
> try to lock that range. If we fail to lock the pages in that range we will
> shrink the max bytes to a single page and re loop. However if our first page is
> inside of the delalloc range then we will end up limiting the end of the range
> to a period before our first page. This is illustrated below
>
> [0 -------- delalloc range --------- 256mb]
> [page]
>
> So find_delalloc_range will return with delalloc_start as 0 and end as 128mb,
> and then we will notice that delalloc_start < *start and adjust it up, but not
> adjust delalloc_end up, so things go sideways. To fix this we need to not limit
This makes me more confused...
so do you mean that 'delalloc_end < delalloc_start' leads to the not locked pages?
-liubo
thanks,
> the max bytes in find_delalloc_range, but in find_lock_delalloc_range and that
> way we don't end up with this confusion. Thanks,
>
> Signed-off-by: Josef Bacik <jbacik@xxxxxxxxxxxx>
> ---
> fs/btrfs/extent_io.c | 12 ++++--------
> 1 file changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index b48942f..2bf6f46 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -1491,10 +1491,8 @@ static noinline u64 find_delalloc_range(struct extent_io_tree *tree,
> cur_start = state->end + 1;
> node = rb_next(node);
> total_bytes += state->end - state->start + 1;
> - if (total_bytes >= max_bytes) {
> - *end = *start + max_bytes - 1;
> + if (total_bytes >= max_bytes)
> break;
> - }
> if (!node)
> break;
> }
> @@ -1636,10 +1634,9 @@ again:
>
> /*
> * make sure to limit the number of pages we try to lock down
> - * if we're looping.
> */
> - if (delalloc_end + 1 - delalloc_start > max_bytes && loops)
> - delalloc_end = delalloc_start + PAGE_CACHE_SIZE - 1;
> + if (delalloc_end + 1 - delalloc_start > max_bytes)
> + delalloc_end = delalloc_start + max_bytes - 1;
>
> /* step two, lock all the pages after the page that has start */
> ret = lock_delalloc_pages(inode, locked_page,
> @@ -1650,8 +1647,7 @@ again:
> */
> free_extent_state(cached_state);
> if (!loops) {
> - unsigned long offset = (*start) & (PAGE_CACHE_SIZE - 1);
> - max_bytes = PAGE_CACHE_SIZE - offset;
> + max_bytes = PAGE_CACHE_SIZE;
> loops = 1;
> goto again;
> } else {
> --
> 1.8.3.1
>
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