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dm thin: switch to an atomic_t for tracking pending new block preparations

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Previously we used separate boolean values to track quiescing and
copying actions.  By switching to an atomic_t we can support blocks that
need a partial copy and partial zero.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2014-06-13 13:57:09 +01:00 committed by Mike Snitzer
parent 6afbc01d75
commit 50f3c3efdd
1 changed files with 16 additions and 13 deletions
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29
drivers/md/dm-thin.c
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@ -554,11 +554,16 @@ static void remap_and_issue(struct thin_c *tc, struct bio *bio,
struct dm_thin_new_mapping {
struct list_head list;
bool quiesced:1;
bool prepared:1;
bool pass_discard:1;
bool definitely_not_shared:1;
/*
* Track quiescing, copying and zeroing preparation actions. When this
* counter hits zero the block is prepared and can be inserted into the
* btree.
*/
atomic_t prepare_actions;
int err;
struct thin_c *tc;
dm_block_t virt_block;
@ -575,11 +580,11 @@ struct dm_thin_new_mapping {
bio_end_io_t *saved_bi_end_io;
};
static void __maybe_add_mapping(struct dm_thin_new_mapping *m)
static void __complete_mapping_preparation(struct dm_thin_new_mapping *m)
{
struct pool *pool = m->tc->pool;
if (m->quiesced && m->prepared) {
if (atomic_dec_and_test(&m->prepare_actions)) {
list_add_tail(&m->list, &pool->prepared_mappings);
wake_worker(pool);
}
@ -594,8 +599,7 @@ static void copy_complete(int read_err, unsigned long write_err, void *context)
m->err = read_err || write_err ? -EIO : 0;
spin_lock_irqsave(&pool->lock, flags);
m->prepared = true;
__maybe_add_mapping(m);
__complete_mapping_preparation(m);
spin_unlock_irqrestore(&pool->lock, flags);
}
@ -609,8 +613,7 @@ static void overwrite_endio(struct bio *bio, int err)
m->err = err;
spin_lock_irqsave(&pool->lock, flags);
m->prepared = true;
__maybe_add_mapping(m);
__complete_mapping_preparation(m);
spin_unlock_irqrestore(&pool->lock, flags);
}
@ -836,7 +839,9 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
m->cell = cell;
if (!dm_deferred_set_add_work(pool->shared_read_ds, &m->list))
m->quiesced = true;
atomic_set(&m->prepare_actions, 1); /* copy only */
else
atomic_set(&m->prepare_actions, 2); /* quiesce + copy */
/*
* IO to pool_dev remaps to the pool target's data_dev.
@ -896,8 +901,7 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
struct pool *pool = tc->pool;
struct dm_thin_new_mapping *m = get_next_mapping(pool);
m->quiesced = true;
m->prepared = false;
atomic_set(&m->prepare_actions, 1); /* no need to quiesce */
m->tc = tc;
m->virt_block = virt_block;
m->data_block = data_block;
@ -3361,8 +3365,7 @@ static int thin_endio(struct dm_target *ti, struct bio *bio, int err)
spin_lock_irqsave(&pool->lock, flags);
list_for_each_entry_safe(m, tmp, &work, list) {
list_del(&m->list);
m->quiesced = true;
__maybe_add_mapping(m);
__complete_mapping_preparation(m);
}
spin_unlock_irqrestore(&pool->lock, flags);
}