From: Jack Qiu <jack.qiu@xxxxxxxxxx> 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@xxxxxxxxxx Fixes: b1058b981272 ("direct-io: submit bio after boundary buffer is added to it") Signed-off-by: Jack Qiu <jack.qiu@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/direct-io.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -810,6 +810,7 @@ submit_page_section(struct dio *dio, str 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) { /* @@ -848,10 +849,10 @@ submit_page_section(struct dio *dio, str 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);
