On 07/10/09 09:49, Mikulas Patocka wrote:
> patch to hold back bios --- untested (and not quite optimal because it
> scans the "failures" list in fixed intervals), but it shows the approach.
>
> ---
> drivers/md/dm-raid1.c | 10 +++++++---
> drivers/md/dm-region-hash.c | 6 +-----
> include/linux/dm-region-hash.h | 3 +--
> 3 files changed, 9 insertions(+), 10 deletions(-)
>
> Index: linux-2.6.31-rc2-devel/drivers/md/dm-raid1.c
> ===================================================================
> --- linux-2.6.31-rc2-devel.orig/drivers/md/dm-raid1.c 2009-07-10 14:48:19.000000000 +0200
> +++ linux-2.6.31-rc2-devel/drivers/md/dm-raid1.c 2009-07-10 15:46:11.000000000 +0200
> @@ -535,11 +535,11 @@ static void write_callback(unsigned long
> else
> uptodate = 1;
>
> - if (unlikely(!uptodate)) {
> + if (unlikely(!uptodate) || !errors_handled(ms)) {
> DMERR("All replicated volumes dead, failing I/O");
> /* None of the writes succeeded, fail the I/O. */
> ret = -EIO;
> - } else if (errors_handled(ms)) {
> + } else {
> /*
> * Need to raise event. Since raising
> * events can block, we need to do it in
> @@ -687,8 +687,12 @@ static void do_failures(struct mirror_se
> if (!ms->log_failure) {
> while ((bio = bio_list_pop(failures))) {
> ms->in_sync = 0;
> - dm_rh_mark_nosync(ms->rh, bio, bio->bi_size, 0);
> + dm_rh_mark_nosync(ms->rh, bio);
> + spin_lock_irq(&ms->lock);
> + bio_list_add(&ms->failures, bio);
> + spin_unlock_irq(&ms->lock);
> }
> + delayed_wake(ms);
> return;
> }
>
> Index: linux-2.6.31-rc2-devel/drivers/md/dm-region-hash.c
> ===================================================================
> --- linux-2.6.31-rc2-devel.orig/drivers/md/dm-region-hash.c 2009-07-10 14:54:07.000000000 +0200
> +++ linux-2.6.31-rc2-devel/drivers/md/dm-region-hash.c 2009-07-10 15:45:07.000000000 +0200
> @@ -392,8 +392,6 @@ static void complete_resync_work(struct
> /* dm_rh_mark_nosync
> * @ms
> * @bio
> - * @done
> - * @error
> *
> * The bio was written on some mirror(s) but failed on other mirror(s).
> * We can successfully endio the bio but should avoid the region being
> @@ -401,8 +399,7 @@ static void complete_resync_work(struct
> *
> * This function is _not_ safe in interrupt context!
> */
> -void dm_rh_mark_nosync(struct dm_region_hash *rh,
> - struct bio *bio, unsigned done, int error)
> +void dm_rh_mark_nosync(struct dm_region_hash *rh, struct bio *bio)
> {
> unsigned long flags;
> struct dm_dirty_log *log = rh->log;
> @@ -439,7 +436,6 @@ void dm_rh_mark_nosync(struct dm_region_
> BUG_ON(!list_empty(®->list));
> spin_unlock_irqrestore(&rh->region_lock, flags);
>
> - bio_endio(bio, error);
How do bios queued in ms->failures are processed later? It seems that
the bios stay in ms->failures forever, and the upper layer can not
receive "success" for those bios. Don't we need a mechanism to block/unblock
write bios to fix this issue?
> if (recovering)
> complete_resync_work(reg, 0);
> }
> Index: linux-2.6.31-rc2-devel/include/linux/dm-region-hash.h
> ===================================================================
> --- linux-2.6.31-rc2-devel.orig/include/linux/dm-region-hash.h 2009-07-10 15:45:26.000000000 +0200
> +++ linux-2.6.31-rc2-devel/include/linux/dm-region-hash.h 2009-07-10 15:45:36.000000000 +0200
> @@ -78,8 +78,7 @@ void dm_rh_dec(struct dm_region_hash *rh
> /* Delay bios on regions. */
> void dm_rh_delay(struct dm_region_hash *rh, struct bio *bio);
>
> -void dm_rh_mark_nosync(struct dm_region_hash *rh,
> - struct bio *bio, unsigned done, int error);
> +void dm_rh_mark_nosync(struct dm_region_hash *rh, struct bio *bio);
>
> /*
> * Region recovery control.
--
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