*/
#define BLOCK_SECTORS (8)
+/*
+ * reclaim runs every 1/4 disk size or 10G reclaimable space. This can prevent
+ * recovery scans a very long log
+ */
+#define RECLAIM_MAX_FREE_SPACE (10 * 1024 * 1024 * 2) /* sector */
+#define RECLAIM_MAX_FREE_SPACE_SHIFT (2)
+
struct r5l_log {
struct md_rdev *rdev;
sector_t device_size; /* log device size, round to
* BLOCK_SECTORS */
+ sector_t max_free_space; /* reclaim run if free space is at
+ * this size */
sector_t last_checkpoint; /* log tail. where recovery scan
* starts from */
struct list_head io_end_ios; /* io_units which have been completely
* written to the log but not yet written
* to the RAID */
+ struct list_head stripe_end_ios;/* io_units which have been completely
+ * written to the RAID but have not yet
+ * been considered for updating super */
struct kmem_cache *io_kc;
+ struct md_thread *reclaim_thread;
+ unsigned long reclaim_target; /* number of space that need to be
+ * reclaimed. if it's 0, reclaim spaces
+ * used by io_units which are in
+ * IO_UNIT_STRIPE_END state (eg, reclaim
+ * dones't wait for specific io_unit
+ * switching to IO_UNIT_STRIPE_END
+ * state) */
+
struct list_head no_space_stripes; /* pending stripes, log has no space */
spinlock_t no_space_stripes_lock;
};
}
}
+/*
+ * We don't want too many io_units reside in stripe_end_ios list, which will
+ * waste a lot of memory. So we try to remove some. But we must keep at least 2
+ * io_units. The superblock must point to a valid meta, if it's the last meta,
+ * recovery can scan less
+ */
+static void r5l_compress_stripe_end_list(struct r5l_log *log)
+{
+ struct r5l_io_unit *first, *last, *io;
+
+ first = list_first_entry(&log->stripe_end_ios,
+ struct r5l_io_unit, log_sibling);
+ last = list_last_entry(&log->stripe_end_ios,
+ struct r5l_io_unit, log_sibling);
+ if (first == last)
+ return;
+ list_del(&first->log_sibling);
+ list_del(&last->log_sibling);
+ while (!list_empty(&log->stripe_end_ios)) {
+ io = list_first_entry(&log->stripe_end_ios,
+ struct r5l_io_unit, log_sibling);
+ list_del(&io->log_sibling);
+ first->log_end = io->log_end;
+ r5l_free_io_unit(log, io);
+ }
+ list_add_tail(&first->log_sibling, &log->stripe_end_ios);
+ list_add_tail(&last->log_sibling, &log->stripe_end_ios);
+}
+
static void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
static void __r5l_set_io_unit_state(struct r5l_io_unit *io,
enum r5l_io_unit_state state)
if (state == IO_UNIT_IO_END)
r5l_move_io_unit_list(&log->running_ios, &log->io_end_ios,
IO_UNIT_IO_END);
+ if (state == IO_UNIT_STRIPE_END) {
+ struct r5l_io_unit *last;
+ sector_t reclaimable_space;
+
+ r5l_move_io_unit_list(&log->io_end_ios, &log->stripe_end_ios,
+ IO_UNIT_STRIPE_END);
+
+ last = list_last_entry(&log->stripe_end_ios,
+ struct r5l_io_unit, log_sibling);
+ reclaimable_space = r5l_ring_distance(log, log->last_checkpoint,
+ last->log_end);
+ if (reclaimable_space >= log->max_free_space)
+ r5l_wake_reclaim(log, 0);
+
+ r5l_compress_stripe_end_list(log);
+ }
wake_up(&io->wait_state);
}
spin_unlock(&log->no_space_stripes_lock);
}
+void r5l_stripe_write_finished(struct stripe_head *sh)
+{
+ struct r5l_io_unit *io;
+
+ /* Don't support stripe batch */
+ io = sh->log_io;
+ if (!io)
+ return;
+ sh->log_io = NULL;
+
+ if (atomic_dec_and_test(&io->pending_stripe))
+ r5l_set_io_unit_state(io, IO_UNIT_STRIPE_END);
+}
+
+/*
+ * Starting dispatch IO to raid.
+ * io_unit(meta) consists of a log. There is one situation we want to avoid. A
+ * broken meta in the middle of a log causes recovery can't find meta at the
+ * head of log. If operations require meta at the head persistent in log, we
+ * must make sure meta before it persistent in log too. A case is:
+ *
+ * stripe data/parity is in log, we start write stripe to raid disks. stripe
+ * data/parity must be persistent in log before we do the write to raid disks.
+ *
+ * The solution is we restrictly maintain io_unit list order. In this case, we
+ * only write stripes of an io_unit to raid disks till the io_unit is the first
+ * one whose data/parity is in log.
+ */
+void r5l_flush_stripe_to_raid(struct r5l_log *log)
+{
+ struct r5l_io_unit *io;
+ struct stripe_head *sh;
+ bool run_stripe;
+
+ if (!log)
+ return;
+ spin_lock_irq(&log->io_list_lock);
+ run_stripe = !list_empty(&log->io_end_ios);
+ spin_unlock_irq(&log->io_list_lock);
+
+ if (!run_stripe)
+ return;
+
+ blkdev_issue_flush(log->rdev->bdev, GFP_NOIO, NULL);
+
+ spin_lock_irq(&log->io_list_lock);
+ list_for_each_entry(io, &log->io_end_ios, log_sibling) {
+ if (io->state >= IO_UNIT_STRIPE_START)
+ continue;
+ __r5l_set_io_unit_state(io, IO_UNIT_STRIPE_START);
+
+ while (!list_empty(&io->stripe_list)) {
+ sh = list_first_entry(&io->stripe_list,
+ struct stripe_head, log_list);
+ list_del_init(&sh->log_list);
+ set_bit(STRIPE_HANDLE, &sh->state);
+ raid5_release_stripe(sh);
+ }
+ }
+ spin_unlock_irq(&log->io_list_lock);
+}
+
+static void r5l_kick_io_unit(struct r5l_log *log, struct r5l_io_unit *io)
+{
+ /* the log thread will write the io unit */
+ wait_event(io->wait_state, io->state >= IO_UNIT_IO_END);
+ if (io->state < IO_UNIT_STRIPE_START)
+ r5l_flush_stripe_to_raid(log);
+ wait_event(io->wait_state, io->state >= IO_UNIT_STRIPE_END);
+}
+
+static void r5l_write_super(struct r5l_log *log, sector_t cp);
+static void r5l_do_reclaim(struct r5l_log *log)
+{
+ struct r5l_io_unit *io, *last;
+ LIST_HEAD(list);
+ sector_t free = 0;
+ sector_t reclaim_target = xchg(&log->reclaim_target, 0);
+
+ spin_lock_irq(&log->io_list_lock);
+ /*
+ * move proper io_unit to reclaim list. We should not change the order.
+ * reclaimable/unreclaimable io_unit can be mixed in the list, we
+ * shouldn't reuse space of an unreclaimable io_unit
+ */
+ while (1) {
+ while (!list_empty(&log->stripe_end_ios)) {
+ io = list_first_entry(&log->stripe_end_ios,
+ struct r5l_io_unit, log_sibling);
+ list_move_tail(&io->log_sibling, &list);
+ free += r5l_ring_distance(log, io->log_start,
+ io->log_end);
+ }
+
+ if (free >= reclaim_target ||
+ (list_empty(&log->running_ios) &&
+ list_empty(&log->io_end_ios) &&
+ list_empty(&log->stripe_end_ios)))
+ break;
+
+ /* Below waiting mostly happens when we shutdown the raid */
+ if (!list_empty(&log->io_end_ios)) {
+ io = list_first_entry(&log->io_end_ios,
+ struct r5l_io_unit, log_sibling);
+ spin_unlock_irq(&log->io_list_lock);
+ /* nobody else can delete the io, we are safe */
+ r5l_kick_io_unit(log, io);
+ spin_lock_irq(&log->io_list_lock);
+ continue;
+ }
+
+ if (!list_empty(&log->running_ios)) {
+ io = list_first_entry(&log->running_ios,
+ struct r5l_io_unit, log_sibling);
+ spin_unlock_irq(&log->io_list_lock);
+ /* nobody else can delete the io, we are safe */
+ r5l_kick_io_unit(log, io);
+ spin_lock_irq(&log->io_list_lock);
+ continue;
+ }
+ }
+ spin_unlock_irq(&log->io_list_lock);
+
+ if (list_empty(&list))
+ return;
+
+ /* super always point to last valid meta */
+ last = list_last_entry(&list, struct r5l_io_unit, log_sibling);
+ /*
+ * write_super will flush cache of each raid disk. We must write super
+ * here, because the log area might be reused soon and we don't want to
+ * confuse recovery
+ */
+ r5l_write_super(log, last->log_start);
+
+ mutex_lock(&log->io_mutex);
+ log->last_checkpoint = last->log_start;
+ log->last_cp_seq = last->seq;
+ mutex_unlock(&log->io_mutex);
+ r5l_run_no_space_stripes(log);
+
+ while (!list_empty(&list)) {
+ io = list_first_entry(&list, struct r5l_io_unit, log_sibling);
+ list_del(&io->log_sibling);
+ r5l_free_io_unit(log, io);
+ }
+}
+
+static void r5l_reclaim_thread(struct md_thread *thread)
+{
+ struct mddev *mddev = thread->mddev;
+ struct r5conf *conf = mddev->private;
+ struct r5l_log *log = conf->log;
+
+ if (!log)
+ return;
+ r5l_do_reclaim(log);
+}
+
static void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
{
- /* will implement later */
+ unsigned long target;
+ unsigned long new = (unsigned long)space; /* overflow in theory */
+
+ do {
+ target = log->reclaim_target;
+ if (new < target)
+ return;
+ } while (cmpxchg(&log->reclaim_target, target, new) != target);
+ md_wakeup_thread(log->reclaim_thread);
}
static int r5l_recovery_log(struct r5l_log *log)
log->last_cp_seq = le64_to_cpu(mb->seq);
log->device_size = round_down(rdev->sectors, BLOCK_SECTORS);
+ log->max_free_space = log->device_size >> RECLAIM_MAX_FREE_SPACE_SHIFT;
+ if (log->max_free_space > RECLAIM_MAX_FREE_SPACE)
+ log->max_free_space = RECLAIM_MAX_FREE_SPACE;
log->last_checkpoint = cp;
__free_page(page);
spin_lock_init(&log->io_list_lock);
INIT_LIST_HEAD(&log->running_ios);
+ INIT_LIST_HEAD(&log->io_end_ios);
+ INIT_LIST_HEAD(&log->stripe_end_ios);
log->io_kc = KMEM_CACHE(r5l_io_unit, 0);
if (!log->io_kc)
goto io_kc;
+ log->reclaim_thread = md_register_thread(r5l_reclaim_thread,
+ log->rdev->mddev, "reclaim");
+ if (!log->reclaim_thread)
+ goto reclaim_thread;
+
INIT_LIST_HEAD(&log->no_space_stripes);
spin_lock_init(&log->no_space_stripes_lock);
conf->log = log;
return 0;
error:
+ md_unregister_thread(&log->reclaim_thread);
+reclaim_thread:
kmem_cache_destroy(log->io_kc);
io_kc:
kfree(log);
void r5l_exit_log(struct r5l_log *log)
{
+ /*
+ * at this point all stripes are finished, so io_unit is at least in
+ * STRIPE_END state
+ */
+ r5l_wake_reclaim(log, -1L);
+ md_unregister_thread(&log->reclaim_thread);
+ r5l_do_reclaim(log);
+ /*
+ * force a super update, r5l_do_reclaim might updated the super.
+ * mddev->thread is already stopped
+ */
+ md_update_sb(log->rdev->mddev, 1);
+
kmem_cache_destroy(log->io_kc);
kfree(log);
}
projects / karo-tx-linux.git / commitdiff