From: Holger Smolinski Date: Wed, 9 May 2007 09:32:50 +0000 (-0700) Subject: dm raid1: one kmirrord per mirror X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=6ad36fe2b451cc85cc7b14f4128286759e217124;p=openwrt%2Fstaging%2Fblogic.git dm raid1: one kmirrord per mirror This patch replaces the single instance of kmirrord by one instance per mirror set. This change is required to avoid a deadlock in kmirrord when the persistent dirty log of a mirror itself resides on a mirror. The single instance of kmirrord then issues a sync write to the dirty log in write_bits which gets deferred to kmirrord itself later in the call chain. But kmirrord never does the deferred work because it is still waiting for the sync write_bits. _mirror_sets is removed as it no longer needed, and we always flush the workqueue before destroying it to ensure all work is complete before destroying it. Signed-off-by: Holger Smolinski Signed-off-by: Alasdair G Kergon Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c index 23a642619bed..c8b4c108da9e 100644 --- a/drivers/md/dm-raid1.c +++ b/drivers/md/dm-raid1.c @@ -22,15 +22,8 @@ #define DM_MSG_PREFIX "raid1" -static struct workqueue_struct *_kmirrord_wq; -static struct work_struct _kmirrord_work; static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped); -static inline void wake(void) -{ - queue_work(_kmirrord_wq, &_kmirrord_work); -} - /*----------------------------------------------------------------- * Region hash * @@ -136,6 +129,9 @@ struct mirror_set { struct mirror *default_mirror; /* Default mirror */ + struct workqueue_struct *kmirrord_wq; + struct work_struct kmirrord_work; + unsigned int nr_mirrors; struct mirror mirror[0]; }; @@ -153,6 +149,11 @@ static inline sector_t region_to_sector(struct region_hash *rh, region_t region) return region << rh->region_shift; } +static void wake(struct mirror_set *ms) +{ + queue_work(ms->kmirrord_wq, &ms->kmirrord_work); +} + /* FIXME move this */ static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw); @@ -471,7 +472,7 @@ static void rh_dec(struct region_hash *rh, region_t region) spin_unlock_irqrestore(&rh->region_lock, flags); if (should_wake) - wake(); + wake(rh->ms); } /* @@ -558,7 +559,7 @@ static void rh_recovery_end(struct region *reg, int success) list_add(®->list, ®->rh->recovered_regions); spin_unlock_irq(&rh->region_lock); - wake(); + wake(rh->ms); } static void rh_flush(struct region_hash *rh) @@ -592,7 +593,7 @@ static void rh_start_recovery(struct region_hash *rh) for (i = 0; i < MAX_RECOVERY; i++) up(&rh->recovery_count); - wake(); + wake(rh->ms); } /* @@ -870,11 +871,10 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes) /*----------------------------------------------------------------- * kmirrord *---------------------------------------------------------------*/ -static LIST_HEAD(_mirror_sets); -static DECLARE_RWSEM(_mirror_sets_lock); - -static void do_mirror(struct mirror_set *ms) +static void do_mirror(struct work_struct *work) { + struct mirror_set *ms =container_of(work, struct mirror_set, + kmirrord_work); struct bio_list reads, writes; spin_lock(&ms->lock); @@ -890,16 +890,6 @@ static void do_mirror(struct mirror_set *ms) do_writes(ms, &writes); } -static void do_work(struct work_struct *ignored) -{ - struct mirror_set *ms; - - down_read(&_mirror_sets_lock); - list_for_each_entry (ms, &_mirror_sets, list) - do_mirror(ms); - up_read(&_mirror_sets_lock); -} - /*----------------------------------------------------------------- * Target functions *---------------------------------------------------------------*/ @@ -978,23 +968,6 @@ static int get_mirror(struct mirror_set *ms, struct dm_target *ti, return 0; } -static int add_mirror_set(struct mirror_set *ms) -{ - down_write(&_mirror_sets_lock); - list_add_tail(&ms->list, &_mirror_sets); - up_write(&_mirror_sets_lock); - wake(); - - return 0; -} - -static void del_mirror_set(struct mirror_set *ms) -{ - down_write(&_mirror_sets_lock); - list_del(&ms->list); - up_write(&_mirror_sets_lock); -} - /* * Create dirty log: log_type #log_params */ @@ -1096,13 +1069,22 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv) ti->private = ms; ti->split_io = ms->rh.region_size; + ms->kmirrord_wq = create_singlethread_workqueue("kmirrord"); + if (!ms->kmirrord_wq) { + DMERR("couldn't start kmirrord"); + free_context(ms, ti, m); + return -ENOMEM; + } + INIT_WORK(&ms->kmirrord_work, do_mirror); + r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client); if (r) { + destroy_workqueue(ms->kmirrord_wq); free_context(ms, ti, ms->nr_mirrors); return r; } - add_mirror_set(ms); + wake(ms); return 0; } @@ -1110,8 +1092,9 @@ static void mirror_dtr(struct dm_target *ti) { struct mirror_set *ms = (struct mirror_set *) ti->private; - del_mirror_set(ms); + flush_workqueue(ms->kmirrord_wq); kcopyd_client_destroy(ms->kcopyd_client); + destroy_workqueue(ms->kmirrord_wq); free_context(ms, ti, ms->nr_mirrors); } @@ -1127,7 +1110,7 @@ static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw) spin_unlock(&ms->lock); if (should_wake) - wake(); + wake(ms); } /* @@ -1270,20 +1253,11 @@ static int __init dm_mirror_init(void) if (r) return r; - _kmirrord_wq = create_singlethread_workqueue("kmirrord"); - if (!_kmirrord_wq) { - DMERR("couldn't start kmirrord"); - dm_dirty_log_exit(); - return r; - } - INIT_WORK(&_kmirrord_work, do_work); - r = dm_register_target(&mirror_target); if (r < 0) { DMERR("%s: Failed to register mirror target", mirror_target.name); dm_dirty_log_exit(); - destroy_workqueue(_kmirrord_wq); } return r; @@ -1297,7 +1271,6 @@ static void __exit dm_mirror_exit(void) if (r < 0) DMERR("%s: unregister failed %d", mirror_target.name, r); - destroy_workqueue(_kmirrord_wq); dm_dirty_log_exit(); }