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dm thin: add mappings to end of prepared_* lists 

Mappings could be processed in descending logical block order,
particularly if buffered IO is used.  This could adversely affect the
latency of IO processing.  Fix this by adding mappings to the end of the
'prepared_mappings' and 'prepared_discards' lists.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
This commit is contained in:
Mike Snitzer 2013-12-11 14:01:20 -05:00
parent 8d30abff75
commit daec338bbd
1 changed files with 3 additions and 3 deletions
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6
drivers/md/dm-thin.c
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@ -535,7 +535,7 @@ static void __maybe_add_mapping(struct dm_thin_new_mapping *m)
struct pool *pool = m->tc->pool;
if (m->quiesced && m->prepared) {
list_add(&m->list, &pool->prepared_mappings);
list_add_tail(&m->list, &pool->prepared_mappings);
wake_worker(pool);
}
}
@ -1058,7 +1058,7 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list)) {
spin_lock_irqsave(&pool->lock, flags);
list_add(&m->list, &pool->prepared_discards);
list_add_tail(&m->list, &pool->prepared_discards);
spin_unlock_irqrestore(&pool->lock, flags);
wake_worker(pool);
}
@ -2919,7 +2919,7 @@ static int thin_endio(struct dm_target *ti, struct bio *bio, int err)
if (!list_empty(&work)) {
spin_lock_irqsave(&pool->lock, flags);
list_for_each_entry_safe(m, tmp, &work, list)
list_add(&m->list, &pool->prepared_discards);
list_add_tail(&m->list, &pool->prepared_discards);
spin_unlock_irqrestore(&pool->lock, flags);
wake_worker(pool);
}