| Message ID | 20191204170638.28163-1-ntsironis@arrikto.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Mike Snitzer |
| Headers | show |
| Series | dm thin: Avoid flushing the data device twice | expand |
On Wed, Dec 04 2019 at 12:06P -0500, Nikos Tsironis <ntsironis@arrikto.com> wrote: > Since we flush the data device as part of a metadata commit, it's > redundant to then submit any deferred REQ_PREFLUSH bios. > > Add a check in process_deferred_bios() for deferred REQ_PREFLUSH bios > and complete them immediately. > > Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com> > --- > drivers/md/dm-thin.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c > index e0be545080d0..40d8a255dbc3 100644 > --- a/drivers/md/dm-thin.c > +++ b/drivers/md/dm-thin.c > @@ -2383,8 +2383,18 @@ static void process_deferred_bios(struct pool *pool) > while ((bio = bio_list_pop(&bio_completions))) > bio_endio(bio); > > - while ((bio = bio_list_pop(&bios))) > - generic_make_request(bio); > + while ((bio = bio_list_pop(&bios))) { > + if (bio->bi_opf & REQ_PREFLUSH) { > + /* > + * We just flushed the data device as part of the > + * metadata commit, so there is no reason to send > + * another flush. > + */ > + bio_endio(bio); > + } else { > + generic_make_request(bio); > + } > + } > } > > static void do_worker(struct work_struct *ws) > -- > 2.11.0 > Don't we need to check if the the bio is an empty flush? I have this incremental: --- drivers/md/dm-thin.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index 40d8a255dbc3..9c9a323c0c30 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -2384,16 +2384,15 @@ static void process_deferred_bios(struct pool *pool) bio_endio(bio); while ((bio = bio_list_pop(&bios))) { - if (bio->bi_opf & REQ_PREFLUSH) { - /* - * We just flushed the data device as part of the - * metadata commit, so there is no reason to send - * another flush. - */ + /* + * The data device was flushed as part of metadata commit, + * so complete additional deferred empty REQ_PREFLUSH bios + * immediately. + */ + if ((bio->bi_opf & REQ_PREFLUSH) && !bio_has_data(bio)) bio_endio(bio); - } else { + else generic_make_request(bio); - } } }
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index e0be545080d0..40d8a255dbc3 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -2383,8 +2383,18 @@ static void process_deferred_bios(struct pool *pool) while ((bio = bio_list_pop(&bio_completions))) bio_endio(bio); - while ((bio = bio_list_pop(&bios))) - generic_make_request(bio); + while ((bio = bio_list_pop(&bios))) { + if (bio->bi_opf & REQ_PREFLUSH) { + /* + * We just flushed the data device as part of the + * metadata commit, so there is no reason to send + * another flush. + */ + bio_endio(bio); + } else { + generic_make_request(bio); + } + } } static void do_worker(struct work_struct *ws)
Since we flush the data device as part of a metadata commit, it's redundant to then submit any deferred REQ_PREFLUSH bios. Add a check in process_deferred_bios() for deferred REQ_PREFLUSH bios and complete them immediately. Signed-off-by: Nikos Tsironis <ntsironis@arrikto.com> --- drivers/md/dm-thin.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)