| Message ID | 1498855388-16990-17-git-send-email-bcache@lists.ewheeler.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2017/7/1 上午4:43, bcache@lists.ewheeler.net wrote: > From: Tang Junhui <tang.junhui@zte.com.cn> > > gc and write-back get raced (see the email "bcache get stucked" I sended > before): > gc thread write-back thread > | |bch_writeback_thread() > |bch_gc_thread() | > | |==>read_dirty() > |==>bch_btree_gc() | > |==>btree_root() //get btree root | > | node write locker | > |==>bch_btree_gc_root() | > | |==>read_dirty_submit() > | |==>write_dirty() > | |==>continue_at(cl, write_dirty_finish, system_wq); > | |==>write_dirty_finish()//excute in system_wq > | |==>bch_btree_insert() > | |==>bch_btree_map_leaf_nodes() > | |==>__bch_btree_map_nodes() > | |==>btree_root //try to get btree root node read lock > | |-----stuck here > |==>bch_btree_set_root() | > |==>bch_journal_meta() | > |==>bch_journal() | > |==>journal_try_write() | > |==>journal_write_unlocked() //journal_full(&c->journal) condition satisfied > |==>continue_at(cl, journal_write, system_wq); //try to excute journal_write in system_wq > | //but work queue is excuting write_dirty_finish() > |==>closure_sync(); //wait journal_write execute over and wake up gc, > | --stuck here > |==>release root node write locker > > This patch alloc a separate work-queue for write-back thread to avoid such > race. > > Signed-off-by: Tang Junhui <tang.junhui@zte.com.cn> > Cc: stable@vger.kernel.org Add a per-cached device work queue is a good idea, it's OK to me. Acked-by: Coly Li <colyli@suse.de> Thansk. Coly > --- > drivers/md/bcache/bcache.h | 1 + > drivers/md/bcache/super.c | 2 ++ > drivers/md/bcache/writeback.c | 8 ++++++-- > 3 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h > index 44123e4..deb0a6c 100644 > --- a/drivers/md/bcache/bcache.h > +++ b/drivers/md/bcache/bcache.h > @@ -333,6 +333,7 @@ struct cached_dev { > /* Limit number of writeback bios in flight */ > struct semaphore in_flight; > struct task_struct *writeback_thread; > + struct workqueue_struct *writeback_write_wq; > > struct keybuf writeback_keys; > > diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c > index e06641e..24cb9b7 100644 > --- a/drivers/md/bcache/super.c > +++ b/drivers/md/bcache/super.c > @@ -1063,6 +1063,8 @@ static void cached_dev_free(struct closure *cl) > cancel_delayed_work_sync(&dc->writeback_rate_update); > if (!IS_ERR_OR_NULL(dc->writeback_thread)) > kthread_stop(dc->writeback_thread); > + if (dc->writeback_write_wq) > + destroy_workqueue(dc->writeback_write_wq); > > mutex_lock(&bch_register_lock); > > diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c > index 4104eaa..4bc5daa 100644 > --- a/drivers/md/bcache/writeback.c > +++ b/drivers/md/bcache/writeback.c > @@ -189,7 +189,7 @@ static void write_dirty(struct closure *cl) > > closure_bio_submit(&io->bio, cl); > > - continue_at(cl, write_dirty_finish, system_wq); > + continue_at(cl, write_dirty_finish, io->dc->writeback_write_wq); > } > > static void read_dirty_endio(struct bio *bio) > @@ -209,7 +209,7 @@ static void read_dirty_submit(struct closure *cl) > > closure_bio_submit(&io->bio, cl); > > - continue_at(cl, write_dirty, system_wq); > + continue_at(cl, write_dirty, io->dc->writeback_write_wq); > } > > static void read_dirty(struct cached_dev *dc) > @@ -527,6 +527,10 @@ void bch_cached_dev_writeback_init(struct cached_dev *dc) > > int bch_cached_dev_writeback_start(struct cached_dev *dc) > { > + dc->writeback_write_wq = alloc_workqueue("bcache_writeback_wq", WQ_MEM_RECLAIM, 0); > + if (!dc->writeback_write_wq) > + return -ENOMEM; > + > dc->writeback_thread = kthread_create(bch_writeback_thread, dc, > "bcache_writeback"); > if (IS_ERR(dc->writeback_thread)) >
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h index 44123e4..deb0a6c 100644 --- a/drivers/md/bcache/bcache.h +++ b/drivers/md/bcache/bcache.h @@ -333,6 +333,7 @@ struct cached_dev { /* Limit number of writeback bios in flight */ struct semaphore in_flight; struct task_struct *writeback_thread; + struct workqueue_struct *writeback_write_wq; struct keybuf writeback_keys; diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index e06641e..24cb9b7 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1063,6 +1063,8 @@ static void cached_dev_free(struct closure *cl) cancel_delayed_work_sync(&dc->writeback_rate_update); if (!IS_ERR_OR_NULL(dc->writeback_thread)) kthread_stop(dc->writeback_thread); + if (dc->writeback_write_wq) + destroy_workqueue(dc->writeback_write_wq); mutex_lock(&bch_register_lock); diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index 4104eaa..4bc5daa 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -189,7 +189,7 @@ static void write_dirty(struct closure *cl) closure_bio_submit(&io->bio, cl); - continue_at(cl, write_dirty_finish, system_wq); + continue_at(cl, write_dirty_finish, io->dc->writeback_write_wq); } static void read_dirty_endio(struct bio *bio) @@ -209,7 +209,7 @@ static void read_dirty_submit(struct closure *cl) closure_bio_submit(&io->bio, cl); - continue_at(cl, write_dirty, system_wq); + continue_at(cl, write_dirty, io->dc->writeback_write_wq); } static void read_dirty(struct cached_dev *dc) @@ -527,6 +527,10 @@ void bch_cached_dev_writeback_init(struct cached_dev *dc) int bch_cached_dev_writeback_start(struct cached_dev *dc) { + dc->writeback_write_wq = alloc_workqueue("bcache_writeback_wq", WQ_MEM_RECLAIM, 0); + if (!dc->writeback_write_wq) + return -ENOMEM; + dc->writeback_thread = kthread_create(bch_writeback_thread, dc, "bcache_writeback"); if (IS_ERR(dc->writeback_thread))