From: Jinliang Zheng Date: Fri, 11 Jul 2025 08:12:07 +0000 (+0800) Subject: iomap: avoid unnecessary ifs_set_range_uptodate() with locks X-Git-Tag: v6.16-rc7~19^2~3 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=177bb4cba97aae951b910d8ca248480715d09009;p=thirdparty%2Flinux.git iomap: avoid unnecessary ifs_set_range_uptodate() with locks In the buffer write path, iomap_set_range_uptodate() is called every time iomap_end_write() is called. But if folio_test_uptodate() holds, we know that all blocks in this folio are already in the uptodate state, so there is no need to go deep into the critical section of state_lock to execute bitmap_set(). This is because the folios always creep towards ifs_is_fully_uptodate() state and once they've gotten there folio_mark_uptodate() is called, which means the folio is uptodate. Then once a folio is uptodate, there is no route back to !uptodate without going through the removal of the folio from the page cache. Therefore, it's fine to use folio_test_uptodate() to short-circuit unnecessary code paths. Although state_lock may not have significant lock contention due to folio lock, this patch at least reduces the number of instructions, especially the expensive lock-prefixed instructions. Signed-off-by: Jinliang Zheng Link: https://lore.kernel.org/20250711081207.1782667-1-alexjlzheng@tencent.com Reviewed-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner --- diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 3729391a18f32..fb4519158f3a7 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -71,6 +71,9 @@ static void iomap_set_range_uptodate(struct folio *folio, size_t off, unsigned long flags; bool uptodate = true; + if (folio_test_uptodate(folio)) + return; + if (ifs) { spin_lock_irqsave(&ifs->state_lock, flags); uptodate = ifs_set_range_uptodate(folio, ifs, off, len);