From: Jack Qiu <jack.qiu@huawei.com> stable inclusion from linux-4.19.187 commit 7de46dc46efd49dc8cc59b52d56c5ab1eb8e8497 -------------------------------- commit df41872b68601059dd4a84858952dcae58acd331 upstream. I encountered a hung task issue, but not a performance one. I run DIO on a device (need lba continuous, for example open channel ssd), maybe hungtask in below case: DIO: Checkpoint: get addr A(at boundary), merge into BIO, no submit because boundary missing flush dirty data(get addr A+1), wait IO(A+1) writeback timeout, because DIO(A) didn't submit get addr A+2 fail, because checkpoint is doing dio_send_cur_page() may clear sdio->boundary, so prevent it from missing a boundary. Link: https://lkml.kernel.org/r/20210322042253.38312-1-jack.qiu@huawei.com Fixes: b1058b981272 ("direct-io: submit bio after boundary buffer is added to it") Signed-off-by: Jack Qiu <jack.qiu@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- fs/direct-io.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/direct-io.c b/fs/direct-io.c index 1abb7634b2d58..ec7c7d1c03297 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -856,6 +856,7 @@ submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page, struct buffer_head *map_bh) { int ret = 0; + int boundary = sdio->boundary; /* dio_send_cur_page may clear it */ if (dio->op == REQ_OP_WRITE) { /* @@ -894,10 +895,10 @@ submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page, sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits; out: /* - * If sdio->boundary then we want to schedule the IO now to + * If boundary then we want to schedule the IO now to * avoid metadata seeks. */ - if (sdio->boundary) { + if (boundary) { ret = dio_send_cur_page(dio, sdio, map_bh); if (sdio->bio) dio_bio_submit(dio, sdio); -- 2.25.1