From f8ee8909ac818e555ef18b57b0ee4b9fd0478b82 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 5 Nov 2021 13:37:13 -0700 Subject: [PATCH] mm: move more expensive part of XA setup out of mapping check The fast path here is not needing any writeback, yet we spend time setting up the xarray lookup data upfront. Move the part that actually needs to iterate the address space mapping into a separate helper, saving ~30% of the time here. Link: https://lkml.kernel.org/r/49f67983-b802-8929-edab-d807f745c9ca@kernel.dk Signed-off-by: Jens Axboe Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/filemap.c | 43 +++++++++++++++++++++++++------------------ 1 file changed, 25 insertions(+), 18 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 28c57c2536d0..938f52702a7a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -639,6 +639,30 @@ static bool mapping_needs_writeback(struct address_space *mapping) return mapping->nrpages; } +static bool filemap_range_has_writeback(struct address_space *mapping, + loff_t start_byte, loff_t end_byte) +{ + XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT); + pgoff_t max = end_byte >> PAGE_SHIFT; + struct page *page; + + if (end_byte < start_byte) + return false; + + rcu_read_lock(); + xas_for_each(&xas, page, max) { + if (xas_retry(&xas, page)) + continue; + if (xa_is_value(page)) + continue; + if (PageDirty(page) || PageLocked(page) || PageWriteback(page)) + break; + } + rcu_read_unlock(); + return page != NULL; + +} + /** * filemap_range_needs_writeback - check if range potentially needs writeback * @mapping: address space within which to check @@ -656,29 +680,12 @@ static bool mapping_needs_writeback(struct address_space *mapping) bool filemap_range_needs_writeback(struct address_space *mapping, loff_t start_byte, loff_t end_byte) { - XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT); - pgoff_t max = end_byte >> PAGE_SHIFT; - struct page *page; - if (!mapping_needs_writeback(mapping)) return false; if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) && !mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) return false; - if (end_byte < start_byte) - return false; - - rcu_read_lock(); - xas_for_each(&xas, page, max) { - if (xas_retry(&xas, page)) - continue; - if (xa_is_value(page)) - continue; - if (PageDirty(page) || PageLocked(page) || PageWriteback(page)) - break; - } - rcu_read_unlock(); - return page != NULL; + return filemap_range_has_writeback(mapping, start_byte, end_byte); } EXPORT_SYMBOL_GPL(filemap_range_needs_writeback); -- 2.11.0