From 8fa8e538e4be359e9042573737632dda35a8700d Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Tue, 16 Jan 2018 06:26:49 -0500 Subject: page cache: Convert filemap_range_has_page to XArray Instead of calling find_get_pages_range() and putting any reference, use xas_find() to iterate over any entries in the range, skipping the shadow/swap entries. Signed-off-by: Matthew Wilcox --- mm/filemap.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) (limited to 'mm/filemap.c') diff --git a/mm/filemap.c b/mm/filemap.c index bedd8680f789..6b36516bc31d 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -455,20 +455,31 @@ EXPORT_SYMBOL(filemap_flush); bool filemap_range_has_page(struct address_space *mapping, loff_t start_byte, loff_t end_byte) { - pgoff_t index = start_byte >> PAGE_SHIFT; - pgoff_t end = end_byte >> PAGE_SHIFT; struct page *page; + XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT); + pgoff_t max = end_byte >> PAGE_SHIFT; if (end_byte < start_byte) return false; - if (mapping->nrpages == 0) - return false; + rcu_read_lock(); + for (;;) { + page = xas_find(&xas, max); + if (xas_retry(&xas, page)) + continue; + /* Shadow entries don't count */ + if (xa_is_value(page)) + continue; + /* + * We don't need to try to pin this page; we're about to + * release the RCU lock anyway. It is enough to know that + * there was a page here recently. + */ + break; + } + rcu_read_unlock(); - if (!find_get_pages_range(mapping, &index, end, 1, &page)) - return false; - put_page(page); - return true; + return page != NULL; } EXPORT_SYMBOL(filemap_range_has_page); -- cgit v1.2.3-55-g7522