From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Matthew Wilcox To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Cc: Matthew Wilcox , Jan Kara , Jeff Layton , Lukas Czerner , Ross Zwisler , Christoph Hellwig , Goldwyn Rodrigues , Nicholas Piggin , Ryusuke Konishi , linux-nilfs@vger.kernel.org, Jaegeuk Kim , Chao Yu , linux-f2fs-devel@lists.sourceforge.net, Oleg Drokin , Andreas Dilger , James Simmons , Mike Kravetz Subject: [PATCH v10 44/62] memfd: Convert shmem_wait_for_pins to XArray Date: Thu, 29 Mar 2018 20:42:27 -0700 Message-Id: <20180330034245.10462-45-willy@infradead.org> In-Reply-To: <20180330034245.10462-1-willy@infradead.org> References: <20180330034245.10462-1-willy@infradead.org> Sender: owner-linux-mm@kvack.org List-ID: From: Matthew Wilcox As with shmem_tag_pins(), hold the lock around the entire loop instead of acquiring & dropping it for each entry we're going to untag. Signed-off-by: Matthew Wilcox --- mm/memfd.c | 61 +++++++++++++++++++++++++------------------------------------ 1 file changed, 25 insertions(+), 36 deletions(-) diff --git a/mm/memfd.c b/mm/memfd.c index 3b299d72df78..0e0835e63af2 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -64,9 +64,7 @@ static void shmem_tag_pins(struct address_space *mapping) */ static int shmem_wait_for_pins(struct address_space *mapping) { - struct radix_tree_iter iter; - void __rcu **slot; - pgoff_t start; + XA_STATE(xas, &mapping->i_pages, 0); struct page *page; int error, scan; @@ -74,7 +72,9 @@ static int shmem_wait_for_pins(struct address_space *mapping) error = 0; for (scan = 0; scan <= LAST_SCAN; scan++) { - if (!radix_tree_tagged(&mapping->i_pages, SHMEM_TAG_PINNED)) + unsigned int tagged = 0; + + if (!xas_tagged(&xas, SHMEM_TAG_PINNED)) break; if (!scan) @@ -82,45 +82,34 @@ static int shmem_wait_for_pins(struct address_space *mapping) else if (schedule_timeout_killable((HZ << scan) / 200)) scan = LAST_SCAN; - start = 0; - rcu_read_lock(); - radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter, - start, SHMEM_TAG_PINNED) { - - page = radix_tree_deref_slot(slot); - if (radix_tree_exception(page)) { - if (radix_tree_deref_retry(page)) { - slot = radix_tree_iter_retry(&iter); - continue; - } - - page = NULL; - } - - if (page && - page_count(page) - page_mapcount(page) != 1) { - if (scan < LAST_SCAN) - goto continue_resched; - + xas_set(&xas, 0); + xas_lock_irq(&xas); + xas_for_each_tag(&xas, page, ULONG_MAX, SHMEM_TAG_PINNED) { + bool clear = true; + if (xa_is_value(page)) + continue; + if (page_count(page) - page_mapcount(page) != 1) { /* * On the last scan, we clean up all those tags * we inserted; but make a note that we still * found pages pinned. */ - error = -EBUSY; - } - - xa_lock_irq(&mapping->i_pages); - radix_tree_tag_clear(&mapping->i_pages, - iter.index, SHMEM_TAG_PINNED); - xa_unlock_irq(&mapping->i_pages); -continue_resched: - if (need_resched()) { - slot = radix_tree_iter_resume(slot, &iter); - cond_resched_rcu(); + if (scan == LAST_SCAN) + error = -EBUSY; + else + clear = false; } + if (clear) + xas_clear_tag(&xas, SHMEM_TAG_PINNED); + if (++tagged % XA_CHECK_SCHED) + continue; + + xas_pause(&xas); + xas_unlock_irq(&xas); + cond_resched(); + xas_lock_irq(&xas); } - rcu_read_unlock(); + xas_unlock_irq(&xas); } return error; -- 2.16.2