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Commit 9b1d6c89 authored by Ming Lin's avatar Ming Lin Committed by Martin K. Petersen
Browse files

lib: scatterlist: move SG pool code from SCSI driver to lib/sg_pool.c 



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: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMing Lin <ming.l@ssi.samsung.com>
Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 65e8617f

drivers/scsi/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

drivers/scsi/scsi_lib.c

+0 −137
Original line number Diff line number Diff line
@@ -14,8 +14,6 @@ 
#include <linux/completion.h>

#include <linux/kernel.h>

#include <linux/export.h>

#include <linux/mempool.h>

#include <linux/slab.h>

#include <linux/init.h>

#include <linux/pci.h>

#include <linux/delay.h>
@@ -40,39 +38,6 @@ 
#include "scsi_logging.h"





#define SG_MEMPOOL_NR		ARRAY_SIZE(sg_pools)

#define SG_MEMPOOL_SIZE		2



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 slab %s\n",

					sgp->name);

			goto cleanup_sdb;

		}



		sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,

						     sgp->slab);

		if (!sgp->pool) {

			printk(KERN_ERR "SCSI: can't init sg mempool %s\n",

					sgp->name);

			goto cleanup_sdb;

		}

	}



	return 0;



cleanup_sdb:

	for (i = 0; i < SG_MEMPOOL_NR; i++) {

		struct sg_pool *sgp = sg_pools + i;

		if (sgp->pool)

			mempool_destroy(sgp->pool);

		if (sgp->slab)

			kmem_cache_destroy(sgp->slab);

	}

	kmem_cache_destroy(scsi_sdb_cache);



	return -ENOMEM;

}



void scsi_exit_queue(void)

{

	int i;



	kmem_cache_destroy(scsi_sdb_cache);



	for (i = 0; i < SG_MEMPOOL_NR; i++) {

		struct sg_pool *sgp = sg_pools + i;

		mempool_destroy(sgp->pool);

		kmem_cache_destroy(sgp->slab);

	}

}



/**

include/linux/scatterlist.h

+25 −0
Original line number Diff line number Diff line
@@ -285,6 +285,31 @@ size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, 
 */

#define SG_MAX_SINGLE_ALLOC		(PAGE_SIZE / sizeof(struct scatterlist))



/*

 * The maximum number of SG segments that we will put inside a

 * scatterlist (unless chaining is used). Should ideally fit inside a

 * single page, to avoid a higher order allocation.  We could define this

 * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order.  The

 * minimum value is 32

 */

#define SG_CHUNK_SIZE	128



/*

 * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit

 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.

 */

#ifdef CONFIG_ARCH_HAS_SG_CHAIN

#define SG_MAX_SEGMENTS	2048

#else

#define SG_MAX_SEGMENTS	SG_CHUNK_SIZE

#endif



#ifdef CONFIG_SG_POOL

void sg_free_table_chained(struct sg_table *table, bool first_chunk);

int sg_alloc_table_chained(struct sg_table *table, int nents,

			   struct scatterlist *first_chunk);

#endif



/*

 * sg page iterator

 *

include/scsi/scsi.h

+0 −19
Original line number Diff line number Diff line
@@ -17,25 +17,6 @@ enum scsi_timeouts { 
	SCSI_DEFAULT_EH_TIMEOUT		= 10 * HZ,

};



/*

 * The maximum number of SG segments that we will put inside a

 * scatterlist (unless chaining is used). Should ideally fit inside a

 * single page, to avoid a higher order allocation.  We could define this

 * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order.  The

 * minimum value is 32

 */

#define SG_CHUNK_SIZE	128



/*

 * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit

 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.

 */

#ifdef CONFIG_ARCH_HAS_SG_CHAIN

#define SG_MAX_SEGMENTS	2048

#else

#define SG_MAX_SEGMENTS	SG_CHUNK_SIZE

#endif



/*

 * DIX-capable adapters effectively support infinite chaining for the

 * protection information scatterlist

lib/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -523,6 +523,13 @@ config SG_SPLIT 
	 a scatterlist. This should be selected by a driver or an API which

	 whishes to split a scatterlist amongst multiple DMA channels.



config SG_POOL

	def_bool n

	help

	 Provides a helper to allocate chained scatterlists. This should be

	 selected by a driver or an API which whishes to allocate chained

	 scatterlist.



#

# sg chaining option

#