From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: mm/filemap: move the iocb checks into filemap_update_page We don't need to give up when a non-blocking request sees a !Uptodate page. We may be able to satisfy the read from a partially-uptodate page. Link: https://lkml.kernel.org/r/20210122160140.223228-13-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Reviewed-by: Kent Overstreet <kent.overstreet@xxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/filemap.c | 24 ++++++++++-------------- 1 file changed, 10 insertions(+), 14 deletions(-) --- a/mm/filemap.c~mm-filemap-move-the-iocb-checks-into-filemap_update_page +++ a/mm/filemap.c @@ -2240,15 +2240,16 @@ static int filemap_update_page(struct ki struct inode *inode = mapping->host; int error; - if (iocb->ki_flags & IOCB_WAITQ) { - error = lock_page_async(page, iocb->ki_waitq); - if (error) - return error; - } else { - if (!trylock_page(page)) { + if (!trylock_page(page)) { + if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO)) + return -EAGAIN; + if (!(iocb->ki_flags & IOCB_WAITQ)) { put_and_wait_on_page_locked(page, TASK_KILLABLE); return AOP_TRUNCATED_PAGE; } + error = __lock_page_async(page, iocb->ki_waitq); + if (error) + return error; } if (!page->mapping) @@ -2366,14 +2367,9 @@ got_pages: } if (!PageUptodate(page)) { - if ((iocb->ki_flags & IOCB_NOWAIT) || - ((iocb->ki_flags & IOCB_WAITQ) && pvec->nr > 1)) { - put_page(page); - pvec->nr--; - err = -EAGAIN; - goto err; - } - + if ((iocb->ki_flags & IOCB_WAITQ) && + pagevec_count(pvec) > 1) + iocb->ki_flags |= IOCB_NOWAIT; err = filemap_update_page(iocb, mapping, iter, page, pg_pos, pg_count); if (err) { _
