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Merge branch 'sg' of git://git.kernel.dk/linux-2.6-block

Browse source 
* 'sg' of git://git.kernel.dk/linux-2.6-block:
  SG: work with the SCSI fixed maximum allocations.
  SG: Convert SCSI to use scatterlist helpers for sg chaining
  SG: Move functions to lib/scatterlist.c and add sg chaining allocator helpers
This commit is contained in:
Linus Torvalds 2008-01-29 08:51:05 +11:00
commit 68fbda7de0
6 changed files with 350 additions and 228 deletions
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146
drivers/scsi/scsi_lib.c
View file

@ -739,138 +739,43 @@ static inline unsigned int scsi_sgtable_index(unsigned short nents)
return index; return index;
} }
struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask) static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
{ {
struct scsi_host_sg_pool *sgp; struct scsi_host_sg_pool *sgp;
struct scatterlist *sgl, *prev, *ret;
unsigned int index; sgp = scsi_sg_pools + scsi_sgtable_index(nents);
int this, left; mempool_free(sgl, sgp->pool);
}
static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
{
struct scsi_host_sg_pool *sgp;
sgp = scsi_sg_pools + scsi_sgtable_index(nents);
return mempool_alloc(sgp->pool, gfp_mask);
}
int scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
{
int ret;
BUG_ON(!cmd->use_sg); BUG_ON(!cmd->use_sg);
left = cmd->use_sg; ret = __sg_alloc_table(&cmd->sg_table, cmd->use_sg,
ret = prev = NULL; SCSI_MAX_SG_SEGMENTS, gfp_mask, scsi_sg_alloc);
do { if (unlikely(ret))
this = left; __sg_free_table(&cmd->sg_table, SCSI_MAX_SG_SEGMENTS,
if (this > SCSI_MAX_SG_SEGMENTS) { scsi_sg_free);
this = SCSI_MAX_SG_SEGMENTS - 1;
index = SG_MEMPOOL_NR - 1;
} else
index = scsi_sgtable_index(this);
left -= this; cmd->request_buffer = cmd->sg_table.sgl;
sgp = scsi_sg_pools + index;
sgl = mempool_alloc(sgp->pool, gfp_mask);
if (unlikely(!sgl))
goto enomem;
sg_init_table(sgl, sgp->size);
/*
* first loop through, set initial index and return value
*/
if (!ret)
ret = sgl;
/*
* chain previous sglist, if any. we know the previous
* sglist must be the biggest one, or we would not have
* ended up doing another loop.
*/
if (prev)
sg_chain(prev, SCSI_MAX_SG_SEGMENTS, sgl);
/*
* if we have nothing left, mark the last segment as
* end-of-list
*/
if (!left)
sg_mark_end(&sgl[this - 1]);
/*
* don't allow subsequent mempool allocs to sleep, it would
* violate the mempool principle.
*/
gfp_mask &= ~__GFP_WAIT;
gfp_mask |= __GFP_HIGH;
prev = sgl;
} while (left);
/*
* ->use_sg may get modified after dma mapping has potentially
* shrunk the number of segments, so keep a copy of it for free.
*/
cmd->__use_sg = cmd->use_sg;
return ret; return ret;
enomem:
if (ret) {
/*
* Free entries chained off ret. Since we were trying to
* allocate another sglist, we know that all entries are of
* the max size.
*/
sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
prev = ret;
ret = &ret[SCSI_MAX_SG_SEGMENTS - 1];
while ((sgl = sg_chain_ptr(ret)) != NULL) {
ret = &sgl[SCSI_MAX_SG_SEGMENTS - 1];
mempool_free(sgl, sgp->pool);
}
mempool_free(prev, sgp->pool);
}
return NULL;
} }
EXPORT_SYMBOL(scsi_alloc_sgtable); EXPORT_SYMBOL(scsi_alloc_sgtable);
void scsi_free_sgtable(struct scsi_cmnd *cmd) void scsi_free_sgtable(struct scsi_cmnd *cmd)
{ {
struct scatterlist *sgl = cmd->request_buffer; __sg_free_table(&cmd->sg_table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
struct scsi_host_sg_pool *sgp;
/*
* if this is the biggest size sglist, check if we have
* chained parts we need to free
*/
if (cmd->__use_sg > SCSI_MAX_SG_SEGMENTS) {
unsigned short this, left;
struct scatterlist *next;
unsigned int index;
left = cmd->__use_sg - (SCSI_MAX_SG_SEGMENTS - 1);
next = sg_chain_ptr(&sgl[SCSI_MAX_SG_SEGMENTS - 1]);
while (left && next) {
sgl = next;
this = left;
if (this > SCSI_MAX_SG_SEGMENTS) {
this = SCSI_MAX_SG_SEGMENTS - 1;
index = SG_MEMPOOL_NR - 1;
} else
index = scsi_sgtable_index(this);
left -= this;
sgp = scsi_sg_pools + index;
if (left)
next = sg_chain_ptr(&sgl[sgp->size - 1]);
mempool_free(sgl, sgp->pool);
}
/*
* Restore original, will be freed below
*/
sgl = cmd->request_buffer;
sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
} else
sgp = scsi_sg_pools + scsi_sgtable_index(cmd->__use_sg);
mempool_free(sgl, sgp->pool);
} }
EXPORT_SYMBOL(scsi_free_sgtable); EXPORT_SYMBOL(scsi_free_sgtable);
@ -1120,8 +1025,7 @@ static int scsi_init_io(struct scsi_cmnd *cmd)
/* /*
* If sg table allocation fails, requeue request later. * If sg table allocation fails, requeue request later.
*/ */
cmd->request_buffer = scsi_alloc_sgtable(cmd, GFP_ATOMIC); if (unlikely(scsi_alloc_sgtable(cmd, GFP_ATOMIC))) {
if (unlikely(!cmd->request_buffer)) {
scsi_unprep_request(req); scsi_unprep_request(req);
return BLKPREP_DEFER; return BLKPREP_DEFER;
} }

3
drivers/scsi/scsi_tgt_lib.c
View file

@ -359,8 +359,7 @@ static int scsi_tgt_init_cmd(struct scsi_cmnd *cmd, gfp_t gfp_mask)
int count; int count;
cmd->use_sg = rq->nr_phys_segments; cmd->use_sg = rq->nr_phys_segments;
cmd->request_buffer = scsi_alloc_sgtable(cmd, gfp_mask); if (scsi_alloc_sgtable(cmd, gfp_mask))
if (!cmd->request_buffer)
return -ENOMEM; return -ENOMEM;
cmd->request_bufflen = rq->data_len; cmd->request_bufflen = rq->data_len;

126
include/linux/scatterlist.h
View file

@ -7,6 +7,12 @@
#include <linux/string.h> #include <linux/string.h>
#include <asm/io.h> #include <asm/io.h>
struct sg_table {
struct scatterlist *sgl; /* the list */
unsigned int nents; /* number of mapped entries */
unsigned int orig_nents; /* original size of list */
};
/* /*
* Notes on SG table design. * Notes on SG table design.
* *
@ -106,71 +112,12 @@ static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
} }
/**
* sg_next - return the next scatterlist entry in a list
* @sg: The current sg entry
*
* Description:
* Usually the next entry will be @sg@ + 1, but if this sg element is part
* of a chained scatterlist, it could jump to the start of a new
* scatterlist array.
*
**/
static inline struct scatterlist *sg_next(struct scatterlist *sg)
{
#ifdef CONFIG_DEBUG_SG
BUG_ON(sg->sg_magic != SG_MAGIC);
#endif
if (sg_is_last(sg))
return NULL;
sg++;
if (unlikely(sg_is_chain(sg)))
sg = sg_chain_ptr(sg);
return sg;
}
/* /*
* Loop over each sg element, following the pointer to a new list if necessary * Loop over each sg element, following the pointer to a new list if necessary
*/ */
#define for_each_sg(sglist, sg, nr, __i) \ #define for_each_sg(sglist, sg, nr, __i) \
for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg)) for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
/**
* sg_last - return the last scatterlist entry in a list
* @sgl: First entry in the scatterlist
* @nents: Number of entries in the scatterlist
*
* Description:
* Should only be used casually, it (currently) scan the entire list
* to get the last entry.
*
* Note that the @sgl@ pointer passed in need not be the first one,
* the important bit is that @nents@ denotes the number of entries that
* exist from @sgl@.
*
**/
static inline struct scatterlist *sg_last(struct scatterlist *sgl,
unsigned int nents)
{
#ifndef ARCH_HAS_SG_CHAIN
struct scatterlist *ret = &sgl[nents - 1];
#else
struct scatterlist *sg, *ret = NULL;
unsigned int i;
for_each_sg(sgl, sg, nents, i)
ret = sg;
#endif
#ifdef CONFIG_DEBUG_SG
BUG_ON(sgl[0].sg_magic != SG_MAGIC);
BUG_ON(!sg_is_last(ret));
#endif
return ret;
}
/** /**
* sg_chain - Chain two sglists together * sg_chain - Chain two sglists together
* @prv: First scatterlist * @prv: First scatterlist
@ -222,47 +169,6 @@ static inline void sg_mark_end(struct scatterlist *sg)
sg->page_link &= ~0x01; sg->page_link &= ~0x01;
} }
/**
* sg_init_table - Initialize SG table
* @sgl: The SG table
* @nents: Number of entries in table
*
* Notes:
* If this is part of a chained sg table, sg_mark_end() should be
* used only on the last table part.
*
**/
static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
{
memset(sgl, 0, sizeof(*sgl) * nents);
#ifdef CONFIG_DEBUG_SG
{
unsigned int i;
for (i = 0; i < nents; i++)
sgl[i].sg_magic = SG_MAGIC;
}
#endif
sg_mark_end(&sgl[nents - 1]);
}
/**
* sg_init_one - Initialize a single entry sg list
* @sg: SG entry
* @buf: Virtual address for IO
* @buflen: IO length
*
* Notes:
* This should not be used on a single entry that is part of a larger
* table. Use sg_init_table() for that.
*
**/
static inline void sg_init_one(struct scatterlist *sg, const void *buf,
unsigned int buflen)
{
sg_init_table(sg, 1);
sg_set_buf(sg, buf, buflen);
}
/** /**
* sg_phys - Return physical address of an sg entry * sg_phys - Return physical address of an sg entry
* @sg: SG entry * @sg: SG entry
@ -293,4 +199,24 @@ static inline void *sg_virt(struct scatterlist *sg)
return page_address(sg_page(sg)) + sg->offset; return page_address(sg_page(sg)) + sg->offset;
} }
struct scatterlist *sg_next(struct scatterlist *);
struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
void sg_init_table(struct scatterlist *, unsigned int);
void sg_init_one(struct scatterlist *, const void *, unsigned int);
typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
void __sg_free_table(struct sg_table *, unsigned int, sg_free_fn *);
void sg_free_table(struct sg_table *);
int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, gfp_t,
sg_alloc_fn *);
int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
/*
* Maximum number of entries that will be allocated in one piece, if
* a list larger than this is required then chaining will be utilized.
*/
#define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
#endif /* _LINUX_SCATTERLIST_H */ #endif /* _LINUX_SCATTERLIST_H */

7
include/scsi/scsi_cmnd.h
View file

@ -8,7 +8,6 @@
#include <linux/scatterlist.h> #include <linux/scatterlist.h>
struct request; struct request;
struct scatterlist;
struct Scsi_Host; struct Scsi_Host;
struct scsi_device; struct scsi_device;
@ -68,8 +67,8 @@ struct scsi_cmnd {
void *request_buffer; /* Actual requested buffer */ void *request_buffer; /* Actual requested buffer */
/* These elements define the operation we ultimately want to perform */ /* These elements define the operation we ultimately want to perform */
struct sg_table sg_table;
unsigned short use_sg; /* Number of pieces of scatter-gather */ unsigned short use_sg; /* Number of pieces of scatter-gather */
unsigned short __use_sg;
unsigned underflow; /* Return error if less than unsigned underflow; /* Return error if less than
this amount is transferred */ this amount is transferred */
@ -128,14 +127,14 @@ extern void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
size_t *offset, size_t *len); size_t *offset, size_t *len);
extern void scsi_kunmap_atomic_sg(void *virt); extern void scsi_kunmap_atomic_sg(void *virt);
extern struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *, gfp_t); extern int scsi_alloc_sgtable(struct scsi_cmnd *, gfp_t);
extern void scsi_free_sgtable(struct scsi_cmnd *); extern void scsi_free_sgtable(struct scsi_cmnd *);
extern int scsi_dma_map(struct scsi_cmnd *cmd); extern int scsi_dma_map(struct scsi_cmnd *cmd);
extern void scsi_dma_unmap(struct scsi_cmnd *cmd); extern void scsi_dma_unmap(struct scsi_cmnd *cmd);
#define scsi_sg_count(cmd) ((cmd)->use_sg) #define scsi_sg_count(cmd) ((cmd)->use_sg)
#define scsi_sglist(cmd) ((struct scatterlist *)(cmd)->request_buffer) #define scsi_sglist(cmd) ((cmd)->sg_table.sgl)
#define scsi_bufflen(cmd) ((cmd)->request_bufflen) #define scsi_bufflen(cmd) ((cmd)->request_bufflen)
static inline void scsi_set_resid(struct scsi_cmnd *cmd, int resid) static inline void scsi_set_resid(struct scsi_cmnd *cmd, int resid)

2
lib/Makefile
View file

@ -6,7 +6,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
rbtree.o radix-tree.o dump_stack.o \ rbtree.o radix-tree.o dump_stack.o \
idr.o int_sqrt.o extable.o prio_tree.o \ idr.o int_sqrt.o extable.o prio_tree.o \
sha1.o irq_regs.o reciprocal_div.o argv_split.o \ sha1.o irq_regs.o reciprocal_div.o argv_split.o \
proportions.o prio_heap.o proportions.o prio_heap.o scatterlist.o
lib-$(CONFIG_MMU) += ioremap.o lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o lib-$(CONFIG_SMP) += cpumask.o

294
lib/scatterlist.c Normal file
View file

@ -0,0 +1,294 @@
/*
* Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
*
* Scatterlist handling helpers.
*
* This source code is licensed under the GNU General Public License,
* Version 2. See the file COPYING for more details.
*/
#include <linux/module.h>
#include <linux/scatterlist.h>
/**
* sg_next - return the next scatterlist entry in a list
* @sg: The current sg entry
*
* Description:
* Usually the next entry will be @sg@ + 1, but if this sg element is part
* of a chained scatterlist, it could jump to the start of a new
* scatterlist array.
*
**/
struct scatterlist *sg_next(struct scatterlist *sg)
{
#ifdef CONFIG_DEBUG_SG
BUG_ON(sg->sg_magic != SG_MAGIC);
#endif
if (sg_is_last(sg))
return NULL;
sg++;
if (unlikely(sg_is_chain(sg)))
sg = sg_chain_ptr(sg);
return sg;
}
EXPORT_SYMBOL(sg_next);
/**
* sg_last - return the last scatterlist entry in a list
* @sgl: First entry in the scatterlist
* @nents: Number of entries in the scatterlist
*
* Description:
* Should only be used casually, it (currently) scans the entire list
* to get the last entry.
*
* Note that the @sgl@ pointer passed in need not be the first one,
* the important bit is that @nents@ denotes the number of entries that
* exist from @sgl@.
*
**/
struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
{
#ifndef ARCH_HAS_SG_CHAIN
struct scatterlist *ret = &sgl[nents - 1];
#else
struct scatterlist *sg, *ret = NULL;
unsigned int i;
for_each_sg(sgl, sg, nents, i)
ret = sg;
#endif
#ifdef CONFIG_DEBUG_SG
BUG_ON(sgl[0].sg_magic != SG_MAGIC);
BUG_ON(!sg_is_last(ret));
#endif
return ret;
}
EXPORT_SYMBOL(sg_last);
/**
* sg_init_table - Initialize SG table
* @sgl: The SG table
* @nents: Number of entries in table
*
* Notes:
* If this is part of a chained sg table, sg_mark_end() should be
* used only on the last table part.
*
**/
void sg_init_table(struct scatterlist *sgl, unsigned int nents)
{
memset(sgl, 0, sizeof(*sgl) * nents);
#ifdef CONFIG_DEBUG_SG
{
unsigned int i;
for (i = 0; i < nents; i++)
sgl[i].sg_magic = SG_MAGIC;
}
#endif
sg_mark_end(&sgl[nents - 1]);
}
EXPORT_SYMBOL(sg_init_table);
/**
* sg_init_one - Initialize a single entry sg list
* @sg: SG entry
* @buf: Virtual address for IO
* @buflen: IO length
*
**/
void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
{
sg_init_table(sg, 1);
sg_set_buf(sg, buf, buflen);
}
EXPORT_SYMBOL(sg_init_one);
/*
* The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
* helpers.
*/
static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
{
if (nents == SG_MAX_SINGLE_ALLOC)
return (struct scatterlist *) __get_free_page(gfp_mask);
else
return kmalloc(nents * sizeof(struct scatterlist), gfp_mask);
}
static void sg_kfree(struct scatterlist *sg, unsigned int nents)
{
if (nents == SG_MAX_SINGLE_ALLOC)
free_page((unsigned long) sg);
else
kfree(sg);
}
/**
* __sg_free_table - Free a previously mapped sg table
* @table: The sg table header to use
* @max_ents: The maximum number of entries per single scatterlist
* @free_fn: Free function
*
* Description:
* Free an sg table previously allocated and setup with
* __sg_alloc_table(). The @max_ents value must be identical to
* that previously used with __sg_alloc_table().
*
**/
void __sg_free_table(struct sg_table *table, unsigned int max_ents,
sg_free_fn *free_fn)
{
struct scatterlist *sgl, *next;
if (unlikely(!table->sgl))
return;
sgl = table->sgl;
while (table->orig_nents) {
unsigned int alloc_size = table->orig_nents;
unsigned int sg_size;
/*
* If we have more than max_ents segments left,
* then assign 'next' to the sg table after the current one.
* sg_size is then one less than alloc size, since the last
* element is the chain pointer.
*/
if (alloc_size > max_ents) {
next = sg_chain_ptr(&sgl[max_ents - 1]);
alloc_size = max_ents;
sg_size = alloc_size - 1;
} else {
sg_size = alloc_size;
next = NULL;
}
table->orig_nents -= sg_size;
free_fn(sgl, alloc_size);
sgl = next;
}
table->sgl = NULL;
}
EXPORT_SYMBOL(__sg_free_table);
/**
* sg_free_table - Free a previously allocated sg table
* @table: The mapped sg table header
*
**/
void sg_free_table(struct sg_table *table)
{
__sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree);
}
EXPORT_SYMBOL(sg_free_table);
/**
* __sg_alloc_table - Allocate and initialize an sg table with given allocator
* @table: The sg table header to use
* @nents: Number of entries in sg list
* @max_ents: The maximum number of entries the allocator returns per call
* @gfp_mask: GFP allocation mask
* @alloc_fn: Allocator to use
*
* Description:
* This function returns a @table @nents long. The allocator is
* defined to return scatterlist chunks of maximum size @max_ents.
* Thus if @nents is bigger than @max_ents, the scatterlists will be
* chained in units of @max_ents.
*
* Notes:
* If this function returns non-0 (eg failure), the caller must call
* __sg_free_table() to cleanup any leftover allocations.
*
**/
int __sg_alloc_table(struct sg_table *table, unsigned int nents,
unsigned int max_ents, gfp_t gfp_mask,
sg_alloc_fn *alloc_fn)
{
struct scatterlist *sg, *prv;
unsigned int left;
#ifndef ARCH_HAS_SG_CHAIN
BUG_ON(nents > max_ents);
#endif
memset(table, 0, sizeof(*table));
left = nents;
prv = NULL;
do {
unsigned int sg_size, alloc_size = left;
if (alloc_size > max_ents) {
alloc_size = max_ents;
sg_size = alloc_size - 1;
} else
sg_size = alloc_size;
left -= sg_size;
sg = alloc_fn(alloc_size, gfp_mask);
if (unlikely(!sg))
return -ENOMEM;
sg_init_table(sg, alloc_size);
table->nents = table->orig_nents += sg_size;
/*
* If this is the first mapping, assign the sg table header.
* If this is not the first mapping, chain previous part.
*/
if (prv)
sg_chain(prv, max_ents, sg);
else
table->sgl = sg;
/*
* If no more entries after this one, mark the end
*/
if (!left)
sg_mark_end(&sg[sg_size - 1]);
/*
* only really needed for mempool backed sg allocations (like
* SCSI), a possible improvement here would be to pass the
* table pointer into the allocator and let that clear these
* flags
*/
gfp_mask &= ~__GFP_WAIT;
gfp_mask |= __GFP_HIGH;
prv = sg;
} while (left);
return 0;
}
EXPORT_SYMBOL(__sg_alloc_table);
/**
* sg_alloc_table - Allocate and initialize an sg table
* @table: The sg table header to use
* @nents: Number of entries in sg list
* @gfp_mask: GFP allocation mask
*
* Description:
* Allocate and initialize an sg table. If @nents@ is larger than
* SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
*
**/
int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
{
int ret;
ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
gfp_mask, sg_kmalloc);
if (unlikely(ret))
__sg_free_table(table, SG_MAX_SINGLE_ALLOC, sg_kfree);
return ret;
}
EXPORT_SYMBOL(sg_alloc_table);