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Subject[PATCH 08/13] dm: add kmem_cache for request-based dm
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This patch prepares some kmem_cache for request-based dm.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Alasdair G Kergon <agk@redhat.com>
---
drivers/md/dm.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 44 insertions(+), 1 deletion(-)
Index: 2.6.27-rc6/drivers/md/dm.c
===================================================================
--- 2.6.27-rc6.orig/drivers/md/dm.c
+++ 2.6.27-rc6/drivers/md/dm.c
@@ -32,6 +32,7 @@ static unsigned int _major = 0;

static DEFINE_SPINLOCK(_minor_lock);
/*
+ * For bio based dm.
* One of these is allocated per bio.
*/
struct dm_io {
@@ -43,6 +44,7 @@ struct dm_io {
};

/*
+ * For bio based dm.
* One of these is allocated per target within a bio. Hopefully
* this will be simplified out one day.
*/
@@ -52,6 +54,31 @@ struct dm_target_io {
union map_info info;
};

+/*
+ * For request based dm.
+ * One of these is allocated per request.
+ *
+ * Since assuming "original request : cloned request = 1 : 1" and
+ * a counter for number of clones like struct dm_io.io_count isn't needed,
+ * struct dm_io and struct target_io can be merged.
+ */
+struct dm_rq_target_io {
+ struct mapped_device *md;
+ struct dm_target *ti;
+ struct request *orig, clone;
+ int error;
+ union map_info info;
+};
+
+/*
+ * For request based dm.
+ * One of these is allocated per bio.
+ */
+struct dm_clone_bio_info {
+ struct bio *orig;
+ struct request *rq;
+};
+
union map_info *dm_get_mapinfo(struct bio *bio)
{
if (bio && bio->bi_private)
@@ -147,6 +174,8 @@ struct mapped_device {
#define MIN_IOS 256
static struct kmem_cache *_io_cache;
static struct kmem_cache *_tio_cache;
+static struct kmem_cache *_rq_tio_cache;
+static struct kmem_cache *_bio_info_cache;

static int __init local_init(void)
{
@@ -162,9 +191,17 @@ static int __init local_init(void)
if (!_tio_cache)
goto out_free_io_cache;

+ _rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);
+ if (!_rq_tio_cache)
+ goto out_free_tio_cache;
+
+ _bio_info_cache = KMEM_CACHE(dm_clone_bio_info, 0);
+ if (!_bio_info_cache)
+ goto out_free_rq_tio_cache;
+
r = dm_uevent_init();
if (r)
- goto out_free_tio_cache;
+ goto out_free_bio_info_cache;

_major = major;
r = register_blkdev(_major, _name);
@@ -178,6 +215,10 @@ static int __init local_init(void)

out_uevent_exit:
dm_uevent_exit();
+out_free_bio_info_cache:
+ kmem_cache_destroy(_bio_info_cache);
+out_free_rq_tio_cache:
+ kmem_cache_destroy(_rq_tio_cache);
out_free_tio_cache:
kmem_cache_destroy(_tio_cache);
out_free_io_cache:
@@ -188,6 +229,8 @@ out_free_io_cache:

static void local_exit(void)
{
+ kmem_cache_destroy(_bio_info_cache);
+ kmem_cache_destroy(_rq_tio_cache);
kmem_cache_destroy(_tio_cache);
kmem_cache_destroy(_io_cache);
unregister_blkdev(_major, _name);

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