dm persistent data: create new dm_block_manager struct

This patch introduces a separate struct for the block_manager.
It also uses IS_ERR to check the return value of dm_bufio_client_create
instead of testing incorrectly for NULL.

Prior to this patch a struct dm_block_manager was really an alias for
a struct dm_bufio_client.  We want to add some functionality to the
block manager that will require extra fields, so this one to one
mapping is no longer valid.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

2 files changed, 41 insertions, 23 deletions

diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 82b82c318f14..afd84cacca4b 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -681,10 +681,11 @@ struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
         bm = dm_block_manager_create(bdev, THIN_METADATA_BLOCK_SIZE,
                                      THIN_METADATA_CACHE_SIZE,
                                      THIN_MAX_CONCURRENT_LOCKS);
-        if (!bm) {
+        if (IS_ERR(bm)) {
+                r = PTR_ERR(bm);
                 DMERR("could not create block manager");
                 kfree(pmd);
-                return ERR_PTR(-ENOMEM);
+                return ERR_PTR(r);
         }
 
         r = superblock_all_zeroes(bm, &create);
@@ -694,7 +695,6 @@ struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
                 return ERR_PTR(r);
         }
 
-
         r = init_pmd(pmd, bm, 0, create);
         if (r) {
                 dm_block_manager_destroy(bm);
diff --git a/drivers/md/persistent-data/dm-block-manager.c b/drivers/md/persistent-data/dm-block-manager.c
index 8ec46dd511f9..c70ad6e303d3 100644
--- a/drivers/md/persistent-data/dm-block-manager.c
+++ b/drivers/md/persistent-data/dm-block-manager.c
@@ -325,11 +325,6 @@ static struct dm_buffer *to_buffer(struct dm_block *b)
         return (struct dm_buffer *) b;
 }
 
-static struct dm_bufio_client *to_bufio(struct dm_block_manager *bm)
-{
-        return (struct dm_bufio_client *) bm;
-}
-
 dm_block_t dm_block_location(struct dm_block *b)
 {
         return dm_bufio_get_block_number(to_buffer(b));
@@ -367,34 +362,57 @@ static void dm_block_manager_write_callback(struct dm_buffer *buf)
 /*----------------------------------------------------------------
  * Public interface
  *--------------------------------------------------------------*/
+struct dm_block_manager {
+        struct dm_bufio_client *bufio;
+};
+
 struct dm_block_manager *dm_block_manager_create(struct block_device *bdev,
                                                  unsigned block_size,
                                                  unsigned cache_size,
                                                  unsigned max_held_per_thread)
 {
-        return (struct dm_block_manager *)
-                dm_bufio_client_create(bdev, block_size, max_held_per_thread,
-                                       sizeof(struct buffer_aux),
-                                       dm_block_manager_alloc_callback,
-                                       dm_block_manager_write_callback);
+        int r;
+        struct dm_block_manager *bm;
+
+        bm = kmalloc(sizeof(*bm), GFP_KERNEL);
+        if (!bm) {
+                r = -ENOMEM;
+                goto bad;
+        }
+
+        bm->bufio = dm_bufio_client_create(bdev, block_size, max_held_per_thread,
+                                           sizeof(struct buffer_aux),
+                                           dm_block_manager_alloc_callback,
+                                           dm_block_manager_write_callback);
+        if (IS_ERR(bm->bufio)) {
+                r = PTR_ERR(bm->bufio);
+                kfree(bm);
+                goto bad;
+        }
+
+        return bm;
+
+bad:
+        return ERR_PTR(r);
 }
 EXPORT_SYMBOL_GPL(dm_block_manager_create);
 
 void dm_block_manager_destroy(struct dm_block_manager *bm)
 {
-        return dm_bufio_client_destroy(to_bufio(bm));
+        dm_bufio_client_destroy(bm->bufio);
+        kfree(bm);
 }
 EXPORT_SYMBOL_GPL(dm_block_manager_destroy);
 
 unsigned dm_bm_block_size(struct dm_block_manager *bm)
 {
-        return dm_bufio_get_block_size(to_bufio(bm));
+        return dm_bufio_get_block_size(bm->bufio);
 }
 EXPORT_SYMBOL_GPL(dm_bm_block_size);
 
 dm_block_t dm_bm_nr_blocks(struct dm_block_manager *bm)
 {
-        return dm_bufio_get_device_size(to_bufio(bm));
+        return dm_bufio_get_device_size(bm->bufio);
 }
 
 static int dm_bm_validate_buffer(struct dm_block_manager *bm,
@@ -406,7 +424,7 @@ static int dm_bm_validate_buffer(struct dm_block_manager *bm,
                 int r;
                 if (!v)
                         return 0;
-                r = v->check(v, (struct dm_block *) buf, dm_bufio_get_block_size(to_bufio(bm)));
+                r = v->check(v, (struct dm_block *) buf, dm_bufio_get_block_size(bm->bufio));
                 if (unlikely(r))
                         return r;
                 aux->validator = v;
@@ -430,7 +448,7 @@ int dm_bm_read_lock(struct dm_block_manager *bm, dm_block_t b,
         void *p;
         int r;
 
-        p = dm_bufio_read(to_bufio(bm), b, (struct dm_buffer **) result);
+        p = dm_bufio_read(bm->bufio, b, (struct dm_buffer **) result);
         if (unlikely(IS_ERR(p)))
                 return PTR_ERR(p);
 
@@ -463,7 +481,7 @@ int dm_bm_write_lock(struct dm_block_manager *bm,
         void *p;
         int r;
 
-        p = dm_bufio_read(to_bufio(bm), b, (struct dm_buffer **) result);
+        p = dm_bufio_read(bm->bufio, b, (struct dm_buffer **) result);
         if (unlikely(IS_ERR(p)))
                 return PTR_ERR(p);
 
@@ -496,7 +514,7 @@ int dm_bm_read_try_lock(struct dm_block_manager *bm,
         void *p;
         int r;
 
-        p = dm_bufio_get(to_bufio(bm), b, (struct dm_buffer **) result);
+        p = dm_bufio_get(bm->bufio, b, (struct dm_buffer **) result);
         if (unlikely(IS_ERR(p)))
                 return PTR_ERR(p);
         if (unlikely(!p))
@@ -529,7 +547,7 @@ int dm_bm_write_lock_zero(struct dm_block_manager *bm,
         struct buffer_aux *aux;
         void *p;
 
-        p = dm_bufio_new(to_bufio(bm), b, (struct dm_buffer **) result);
+        p = dm_bufio_new(bm->bufio, b, (struct dm_buffer **) result);
         if (unlikely(IS_ERR(p)))
                 return PTR_ERR(p);
 
@@ -586,7 +604,7 @@ int dm_bm_flush_and_unlock(struct dm_block_manager *bm,
 {
         int r;
 
-        r = dm_bufio_write_dirty_buffers(to_bufio(bm));
+        r = dm_bufio_write_dirty_buffers(bm->bufio);
         if (unlikely(r)) {
                 dm_bm_unlock(superblock);
                 return r;
@@ -594,7 +612,7 @@ int dm_bm_flush_and_unlock(struct dm_block_manager *bm,
 
         dm_bm_unlock(superblock);
 
-        return dm_bufio_write_dirty_buffers(to_bufio(bm));
+        return dm_bufio_write_dirty_buffers(bm->bufio);
 }
 
 u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor)