On Thu, Dec 13, 2012 at 08:19:12PM +0000, Joe Thornber wrote:
> @@ -87,6 +79,20 @@ void dm_bio_prison_destroy(struct dm_bio_prison *prison)
> }
> EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
>
> +struct dm_bio_prison_cell *
> +dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
Let's keep that on one line.
> +int dm_bio_detain(struct dm_bio_prison *prison,
> + struct dm_cell_key *key,
> + struct bio *inmate,
> + struct dm_bio_prison_cell *memory,
The caller has already allocated 'memory' specifically to hold that struct.
Call it 'new_cell' perhaps? 'cell_prealloc' ?
> + struct dm_bio_prison_cell **ref)
cell_ref ?
> @@ -226,6 +226,53 @@ struct thin_c {
>
> /*----------------------------------------------------------------*/
>
> +static int bio_detain(struct pool *pool, struct dm_cell_key *key, struct bio *bio,
> + struct dm_bio_prison_cell **result)
> +{
> + int r;
> + struct dm_bio_prison_cell *cell;
> +
> + cell = dm_bio_prison_alloc_cell(pool->prison, GFP_NOIO);
> + if (!cell)
> + return -ENOMEM;
Redundant test? The mempool allocation always succeeds (or blocks).
> + r = dm_bio_detain(pool->prison, key, bio, cell, result);
> +
> + if (r)
> + /*
> + * We reused an old cell, or errored; we can get rid of
Can't have errored that I can see.
> + * the new one.
> + */
> + dm_bio_prison_free_cell(pool->prison, cell);
> +
> + return r;
> +}
Alasdair
--- a/dm-bio-prison.c 2013-01-14 19:32:36.000000000 +0000
+++ b/dm-bio-prison.c 2013-01-21 23:09:49.000000000 +0000
@@ -79,8 +79,7 @@
}
EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
-struct dm_bio_prison_cell *
-dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
+struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
{
return mempool_alloc(prison->cell_pool, gfp);
}
--- a/dm-thin.c 2013-01-18 15:00:00.000000000 +0000
+++ b/dm-thin.c 2013-01-21 23:09:48.000000000 +0000
@@ -250,16 +250,16 @@
int r;
struct dm_bio_prison_cell *cell;
+ /*
+ * Allocate a cell from the prison's mempool.
+ * This might block but it can't fail.
+ */
cell = dm_bio_prison_alloc_cell(pool->prison, GFP_NOIO);
- if (!cell)
- return -ENOMEM;
r = dm_bio_detain(pool->prison, key, bio, cell, result);
-
if (r)
/*
- * We reused an old cell, or errored; we can get rid of
- * the new one.
+ * We reused an old cell: get rid of the new one.
*/
dm_bio_prison_free_cell(pool->prison, cell);
--
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