Re: [PATCH v3 5/5] lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c

[Sagi Grimberg]

From: Ming Lin 

Now it's ready to move the mempool based SG chained allocator code from
SCSI driver to lib/sg_pool.c, which will be compiled only based on a Kconfig
symbol CONFIG_SG_POOL.

SCSI selects CONFIG_SG_POOL.

Reviewed-by: Christoph Hellwig 
Signed-off-by: Ming Lin 


Reviewed-by: Sagi Grimberg 
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[PATCH v3 5/5] lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c

[Ming Lin]

From: Ming Lin 

Now it's ready to move the mempool based SG chained allocator code from
SCSI driver to lib/sg_pool.c, which will be compiled only based on a Kconfig
symbol CONFIG_SG_POOL.

SCSI selects CONFIG_SG_POOL.

Reviewed-by: Christoph Hellwig 
Signed-off-by: Ming Lin 
---
 drivers/scsi/Kconfig|   1 +
 drivers/scsi/scsi_lib.c | 137 ---
 include/linux/scatterlist.h |  25 +++
 include/scsi/scsi.h |  19 -
 lib/Kconfig |   7 ++
 lib/Makefile|   1 +
 lib/sg_pool.c   | 172 
 7 files changed, 206 insertions(+), 156 deletions(-)
 create mode 100644 lib/sg_pool.c

diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
index 0950567..98e5d51 100644
--- a/drivers/scsi/Kconfig
+++ b/drivers/scsi/Kconfig
@@ -17,6 +17,7 @@ config SCSI
tristate "SCSI device support"
depends on BLOCK
select SCSI_DMA if HAS_DMA
+   select SG_POOL
---help---
  If you want to use a SCSI hard disk, SCSI tape drive, SCSI CD-ROM or
  any other SCSI device under Linux, say Y and make sure that you know
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 8f776f1..b920c5d 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -14,8 +14,6 @@
 #include 
 #include 
 #include 
-#include 
-#include 
 #include 
 #include 
 #include 
@@ -40,39 +38,6 @@
 #include "scsi_logging.h"
 
 
-#define SG_MEMPOOL_NR  ARRAY_SIZE(sg_pools)
-#define SG_MEMPOOL_SIZE2
-
-struct sg_pool {
-   size_t  size;
-   char*name;
-   struct kmem_cache   *slab;
-   mempool_t   *pool;
-};
-
-#define SP(x) { .size = x, "sgpool-" __stringify(x) }
-#if (SG_CHUNK_SIZE < 32)
-#error SG_CHUNK_SIZE is too small (must be 32 or greater)
-#endif
-static struct sg_pool sg_pools[] = {
-   SP(8),
-   SP(16),
-#if (SG_CHUNK_SIZE > 32)
-   SP(32),
-#if (SG_CHUNK_SIZE > 64)
-   SP(64),
-#if (SG_CHUNK_SIZE > 128)
-   SP(128),
-#if (SG_CHUNK_SIZE > 256)
-#error SG_CHUNK_SIZE is too large (256 MAX)
-#endif
-#endif
-#endif
-#endif
-   SP(SG_CHUNK_SIZE)
-};
-#undef SP
-
 struct kmem_cache *scsi_sdb_cache;
 
 /*
@@ -553,65 +518,6 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
scsi_run_queue(sdev->request_queue);
 }
 
-static inline unsigned int sg_pool_index(unsigned short nents)
-{
-   unsigned int index;
-
-   BUG_ON(nents > SG_CHUNK_SIZE);
-
-   if (nents <= 8)
-   index = 0;
-   else
-   index = get_count_order(nents) - 3;
-
-   return index;
-}
-
-static void sg_pool_free(struct scatterlist *sgl, unsigned int nents)
-{
-   struct sg_pool *sgp;
-
-   sgp = sg_pools + sg_pool_index(nents);
-   mempool_free(sgl, sgp->pool);
-}
-
-static struct scatterlist *sg_pool_alloc(unsigned int nents, gfp_t gfp_mask)
-{
-   struct sg_pool *sgp;
-
-   sgp = sg_pools + sg_pool_index(nents);
-   return mempool_alloc(sgp->pool, gfp_mask);
-}
-
-static void sg_free_table_chained(struct sg_table *table, bool first_chunk)
-{
-   if (first_chunk && table->orig_nents <= SG_CHUNK_SIZE)
-   return;
-   __sg_free_table(table, SG_CHUNK_SIZE, first_chunk, sg_pool_free);
-}
-
-static int sg_alloc_table_chained(struct sg_table *table, int nents,
-   struct scatterlist *first_chunk)
-{
-   int ret;
-
-   BUG_ON(!nents);
-
-   if (first_chunk) {
-   if (nents <= SG_CHUNK_SIZE) {
-   table->nents = table->orig_nents = nents;
-   sg_init_table(table->sgl, nents);
-   return 0;
-   }
-   }
-
-   ret = __sg_alloc_table(table, nents, SG_CHUNK_SIZE,
-  first_chunk, GFP_ATOMIC, sg_pool_alloc);
-   if (unlikely(ret))
-   sg_free_table_chained(table, (bool)first_chunk);
-   return ret;
-}
-
 static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
 {
if (cmd->request->cmd_type == REQ_TYPE_FS) {
@@ -2269,8 +2175,6 @@ EXPORT_SYMBOL(scsi_unblock_requests);
 
 int __init scsi_init_queue(void)
 {
-   int i;
-
scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
   sizeof(struct scsi_data_buffer),
   0, 0, NULL);
@@ -2279,53 +2183,12 @@ int __init scsi_init_queue(void)
return -ENOMEM;
}
 
-   for (i = 0; i < SG_MEMPOOL_NR; i++) {
-   struct sg_pool *sgp = sg_pools + i;
-   int size = sgp->size * sizeof(struct scatterlist);
-
-   sgp->slab = kmem_cache_create(sgp->name, size, 0,
-   SLAB_HWCACHE_ALIGN, NULL);
-   if (!sgp->slab) {
-   printk(KERN_ERR "SCSI: can't init sg