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

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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 <hch@lst.de>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Ming Lin 2016-04-04 14:48:11 -07:00 committed by Martin K. Petersen
parent 65e8617fba
commit 9b1d6c8950
7 changed files with 206 additions and 156 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
drivers/scsi/Kconfig
View file

@ -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

137
drivers/scsi/scsi_lib.c
View file

@ -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);
}
}
/**

25
include/linux/scatterlist.h
View file

@ -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
*

19
include/scsi/scsi.h
View file

@ -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

7
lib/Kconfig
View file

@ -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
#

1
lib/Makefile
View file

@ -178,6 +178,7 @@ obj-$(CONFIG_GENERIC_STRNLEN_USER) += strnlen_user.o
obj-$(CONFIG_GENERIC_NET_UTILS) += net_utils.o
obj-$(CONFIG_SG_SPLIT) += sg_split.o
obj-$(CONFIG_SG_POOL) += sg_pool.o
obj-$(CONFIG_STMP_DEVICE) += stmp_device.o
obj-$(CONFIG_IRQ_POLL) += irq_poll.o

172
lib/sg_pool.c Normal file
View file

@ -0,0 +1,172 @@
#include <linux/module.h>
#include <linux/scatterlist.h>
#include <linux/mempool.h>
#include <linux/slab.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
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);
}
/**
* sg_free_table_chained - Free a previously mapped sg table
* @table: The sg table header to use
* @first_chunk: was first_chunk not NULL in sg_alloc_table_chained?
*
* Description:
* Free an sg table previously allocated and setup with
* sg_alloc_table_chained().
*
**/
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);
}
EXPORT_SYMBOL_GPL(sg_free_table_chained);
/**
* sg_alloc_table_chained - Allocate and chain SGLs in an sg table
* @table: The sg table header to use
* @nents: Number of entries in sg list
* @first_chunk: first SGL
*
* Description:
* Allocate and chain SGLs in an sg table. If @nents@ is larger than
* SG_CHUNK_SIZE a chained sg table will be setup.
*
**/
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;
}
EXPORT_SYMBOL_GPL(sg_alloc_table_chained);
static __init int sg_pool_init(void)
{
int i;
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 "SG_POOL: 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 "SG_POOL: 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);
}
return -ENOMEM;
}
static __exit void sg_pool_exit(void)
{
int i;
for (i = 0; i < SG_MEMPOOL_NR; i++) {
struct sg_pool *sgp = sg_pools + i;
mempool_destroy(sgp->pool);
kmem_cache_destroy(sgp->slab);
}
}
module_init(sg_pool_init);
module_exit(sg_pool_exit);