On 7/24/17 17:03, Christoph Hellwig wrote: > On Mon, Jul 24, 2017 at 04:44:22PM +0900, Damien Le Moal wrote: >> Avoid metadata flush to be blocked by the writeback throttling code in >> wbt_wait(). Otherwise, we can end up with a deadlock under heavy write >> load with all chunk works active. In such situation, a deadlock can >> happen if the flush work is blocked by the throttling code while holding >> the metadata lock: as the chunk works will wait for the metadata lock >> too, no progress can be made. >> >> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx> >> --- >> drivers/md/dm-zoned-metadata.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/md/dm-zoned-metadata.c b/drivers/md/dm-zoned-metadata.c >> index 884ff7c170a0..f694fb98b002 100644 >> --- a/drivers/md/dm-zoned-metadata.c >> +++ b/drivers/md/dm-zoned-metadata.c >> @@ -567,7 +567,8 @@ static void dmz_write_mblock(struct dmz_metadata *zmd, struct dmz_mblock *mblk, >> bio->bi_bdev = zmd->dev->bdev; >> bio->bi_private = mblk; >> bio->bi_end_io = dmz_mblock_bio_end_io; >> - bio_set_op_attrs(bio, REQ_OP_WRITE, REQ_META | REQ_PRIO); >> + bio_set_op_attrs(bio, REQ_OP_WRITE, >> + REQ_META | REQ_PRIO | REQ_SYNC | REQ_IDLE); > > Please just assign bi_opf directly instea dof using bio_set_op_attrs > in new code. OK. Will do. > Also what do you need REQ_IDLE for? It is not really needed here, but the wbt_should_throttle() code test is: if ((bio->bi_opf & (REQ_SYNC | REQ_IDLE)) == (REQ_SYNC | REQ_IDLE)) return false; No if REQ_IDLE is not set, wbt will trigger. Having a req flag that says "no wb throttling please" would be a lot cleaner... -- Damien Le Moal, Western Digital -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
