From 3239d834847627b6634a4139cf1dc58f6f137a46 Mon Sep 17 00:00:00 2001 From: Milosz Tanski Date: Tue, 29 Aug 2017 16:13:19 +0200 Subject: [PATCH] fs: support IOCB_NOWAIT in generic_file_buffered_read Allow generic_file_buffered_read to bail out early instead of waiting for the page lock or reading a page if IOCB_NOWAIT is specified. Signed-off-by: Milosz Tanski Reviewed-by: Christoph Hellwig Reviewed-by: Jeff Moyer Acked-by: Sage Weil Signed-off-by: Al Viro --- mm/filemap.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/mm/filemap.c b/mm/filemap.c index b7c039669020..92d4e0a6c012 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1939,6 +1939,8 @@ find_page: page = find_get_page(mapping, index); if (!page) { + if (iocb->ki_flags & IOCB_NOWAIT) + goto would_block; page_cache_sync_readahead(mapping, ra, filp, index, last_index - index); @@ -1952,6 +1954,11 @@ find_page: index, last_index - index); } if (!PageUptodate(page)) { + if (iocb->ki_flags & IOCB_NOWAIT) { + put_page(page); + goto would_block; + } + /* * See comment in do_read_cache_page on why * wait_on_page_locked is used to avoid unnecessarily @@ -2133,6 +2140,8 @@ no_cached_page: goto readpage; } +would_block: + error = -EAGAIN; out: ra->prev_pos = prev_index; ra->prev_pos <<= PAGE_SHIFT; -- 2.20.1