diff options
Diffstat (limited to 'include/linux/mm_inline.h')
| -rw-r--r-- | include/linux/mm_inline.h | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index d6c1011b38f2..f6a2b2d20016 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -617,4 +617,40 @@ static inline bool vma_has_recency(const struct vm_area_struct *vma) return true; } +/** + * num_pages_contiguous() - determine the number of contiguous pages + * that represent contiguous PFNs + * @pages: an array of page pointers + * @nr_pages: length of the array, at least 1 + * + * Determine the number of contiguous pages that represent contiguous PFNs + * in @pages, starting from the first page. + * + * In some kernel configs contiguous PFNs will not have contiguous struct + * pages. In these configurations num_pages_contiguous() will return a num + * smaller than ideal number. The caller should continue to check for pfn + * contiguity after each call to num_pages_contiguous(). + * + * Returns the number of contiguous pages. + */ +static inline size_t num_pages_contiguous(struct page **pages, size_t nr_pages) +{ + struct page *cur_page = pages[0]; + unsigned long section = memdesc_section(cur_page->flags); + size_t i; + + for (i = 1; i < nr_pages; i++) { + if (++cur_page != pages[i]) + break; + /* + * In unproblematic kernel configs, page_to_section() == 0 and + * the whole check will get optimized out. + */ + if (memdesc_section(cur_page->flags) != section) + break; + } + + return i; +} + #endif |