[PATCH v6 53/99] fs: Convert writeback to XArray

From: Matthew Wilcox
Date: Wed Jan 17 2018 - 15:47:10 EST


From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>

A couple of short loops.

Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
---
fs/fs-writeback.c | 25 +++++++++----------------
1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index e2c1ca667d9a..897a89489fe9 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -339,9 +339,9 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
struct address_space *mapping = inode->i_mapping;
struct bdi_writeback *old_wb = inode->i_wb;
struct bdi_writeback *new_wb = isw->new_wb;
- struct radix_tree_iter iter;
+ XA_STATE(xas, &mapping->pages, 0);
+ struct page *page;
bool switched = false;
- void **slot;

/*
* By the time control reaches here, RCU grace period has passed
@@ -375,25 +375,18 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
* to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to
* pages actually under writeback.
*/
- radix_tree_for_each_tagged(slot, &mapping->pages, &iter, 0,
- PAGECACHE_TAG_DIRTY) {
- struct page *page = radix_tree_deref_slot_protected(slot,
- &mapping->pages.xa_lock);
- if (likely(page) && PageDirty(page)) {
+ xas_for_each_tag(&xas, page, ULONG_MAX, PAGECACHE_TAG_DIRTY) {
+ if (PageDirty(page)) {
dec_wb_stat(old_wb, WB_RECLAIMABLE);
inc_wb_stat(new_wb, WB_RECLAIMABLE);
}
}

- radix_tree_for_each_tagged(slot, &mapping->pages, &iter, 0,
- PAGECACHE_TAG_WRITEBACK) {
- struct page *page = radix_tree_deref_slot_protected(slot,
- &mapping->pages.xa_lock);
- if (likely(page)) {
- WARN_ON_ONCE(!PageWriteback(page));
- dec_wb_stat(old_wb, WB_WRITEBACK);
- inc_wb_stat(new_wb, WB_WRITEBACK);
- }
+ xas_set(&xas, 0);
+ xas_for_each_tag(&xas, page, ULONG_MAX, PAGECACHE_TAG_WRITEBACK) {
+ WARN_ON_ONCE(!PageWriteback(page));
+ dec_wb_stat(old_wb, WB_WRITEBACK);
+ inc_wb_stat(new_wb, WB_WRITEBACK);
}

wb_get(new_wb);
--
2.15.1