diff options
| -rw-r--r-- | drivers/md/md.c | 56 | ||||
| -rw-r--r-- | drivers/md/md.h | 4 |
2 files changed, 60 insertions, 0 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index fb11170c717e..6e853c61d87e 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -445,6 +445,61 @@ void md_flush_request(mddev_t *mddev, struct bio *bio) } EXPORT_SYMBOL(md_flush_request); +/* Support for plugging. + * This mirrors the plugging support in request_queue, but does not + * require having a whole queue or request structures. + * We allocate an md_plug_cb for each md device and each thread it gets + * plugged on. This links tot the private plug_handle structure in the + * personality data where we keep a count of the number of outstanding + * plugs so other code can see if a plug is active. + */ +struct md_plug_cb { + struct blk_plug_cb cb; + mddev_t *mddev; +}; + +static void plugger_unplug(struct blk_plug_cb *cb) +{ + struct md_plug_cb *mdcb = container_of(cb, struct md_plug_cb, cb); + if (atomic_dec_and_test(&mdcb->mddev->plug_cnt)) + md_wakeup_thread(mdcb->mddev->thread); + kfree(mdcb); +} + +/* Check that an unplug wakeup will come shortly. + * If not, wakeup the md thread immediately + */ +int mddev_check_plugged(mddev_t *mddev) +{ + struct blk_plug *plug = current->plug; + struct md_plug_cb *mdcb; + + if (!plug) + return 0; + + list_for_each_entry(mdcb, &plug->cb_list, cb.list) { + if (mdcb->cb.callback == plugger_unplug && + mdcb->mddev == mddev) { + /* Already on the list, move to top */ + if (mdcb != list_first_entry(&plug->cb_list, + struct md_plug_cb, + cb.list)) + list_move(&mdcb->cb.list, &plug->cb_list); + return 1; + } + } + /* Not currently on the callback list */ + mdcb = kmalloc(sizeof(*mdcb), GFP_ATOMIC); + if (!mdcb) + return 0; + + mdcb->mddev = mddev; + mdcb->cb.callback = plugger_unplug; + atomic_inc(&mddev->plug_cnt); + list_add(&mdcb->cb.list, &plug->cb_list); + return 1; +} +EXPORT_SYMBOL_GPL(mddev_check_plugged); static inline mddev_t *mddev_get(mddev_t *mddev) { @@ -494,6 +549,7 @@ void mddev_init(mddev_t *mddev) atomic_set(&mddev->active, 1); atomic_set(&mddev->openers, 0); atomic_set(&mddev->active_io, 0); + atomic_set(&mddev->plug_cnt, 0); spin_lock_init(&mddev->write_lock); atomic_set(&mddev->flush_pending, 0); init_waitqueue_head(&mddev->sb_wait); diff --git a/drivers/md/md.h b/drivers/md/md.h index fad90228672f..0b1fd3f1d85b 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -179,6 +179,9 @@ struct mddev_s int delta_disks, new_level, new_layout; int new_chunk_sectors; + atomic_t plug_cnt; /* If device is expecting + * more bios soon. + */ struct mdk_thread_s *thread; /* management thread */ struct mdk_thread_s *sync_thread; /* doing resync or reconstruct */ sector_t curr_resync; /* last block scheduled */ @@ -508,4 +511,5 @@ extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask, mddev_t *mddev); extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs, mddev_t *mddev); +extern int mddev_check_plugged(mddev_t *mddev); #endif /* _MD_MD_H */ |