>From 7b2421e1c075d3c262e28d0598608141add2e7da Mon Sep 17 00:00:00 2001
From: Jens Axboe <jens.axboe@xxxxxxxxxx>
Date: Wed, 14 Nov 2007 12:36:47 +0100
Subject: [PATCH] SG: Convert SCSI to use scatterlist helpers for sg chaining
Also change scsi_alloc_sgtable() to just return 0/failure, since it
maps to the command passed in. ->request_buffer is now no longer needed,
once drivers are adapted to use scsi_sglist() it can be killed.
Signed-off-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
---
drivers/scsi/scsi_lib.c | 137 ++++++-------------------------------------
drivers/scsi/scsi_tgt_lib.c | 3 +-
include/scsi/scsi_cmnd.h | 7 +-
3 files changed, 23 insertions(+), 124 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 0e81e4c..1fb3c2e 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -737,138 +737,40 @@ static inline unsigned int scsi_sgtable_index(unsigned short nents)
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 scatterlist *sgl, *prev, *ret;
- unsigned int index;
- int this, left;
-
- BUG_ON(!cmd->use_sg);
-
- left = cmd->use_sg;
- ret = prev = NULL;
- do {
- 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;
-
- sgl = mempool_alloc(sgp->pool, gfp_mask);
- if (unlikely(!sgl))
- goto enomem;
+ sgp = scsi_sg_pools + scsi_sgtable_index(nents);
+ mempool_free(sgl, sgp->pool);
+}
- sg_init_table(sgl, sgp->size);
+static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
+{
+ struct scsi_host_sg_pool *sgp;
- /*
- * first loop through, set initial index and return value
- */
- if (!ret)
- ret = sgl;
+ sgp = scsi_sg_pools + scsi_sgtable_index(nents);
+ return mempool_alloc(sgp->pool, gfp_mask);
+}
- /*
- * 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);
+int scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
+{
+ int ret;
- /*
- * if we have nothing left, mark the last segment as
- * end-of-list
- */
- if (!left)
- sg_mark_end(&sgl[this - 1]);
+ BUG_ON(!cmd->use_sg);
- /*
- * 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);
+ ret = __sg_alloc_table(&cmd->sg_table, cmd->use_sg, gfp_mask,
+ scsi_sg_alloc, scsi_sg_free);
- /*
- * ->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;
+ cmd->request_buffer = cmd->sg_table.sgl;
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);
void scsi_free_sgtable(struct scsi_cmnd *cmd)
{
- struct scatterlist *sgl = cmd->request_buffer;
- 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);
+ __sg_free_table(&cmd->sg_table, scsi_sg_free);
}
EXPORT_SYMBOL(scsi_free_sgtable);
@@ -1119,8 +1021,7 @@ static int scsi_init_io(struct scsi_cmnd *cmd)
/*
* If sg table allocation fails, requeue request later.
*/
- cmd->request_buffer = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
- if (unlikely(!cmd->request_buffer)) {
+ if (unlikely(scsi_alloc_sgtable(cmd, GFP_ATOMIC))) {
scsi_unprep_request(req);
return BLKPREP_DEFER;
}
diff --git a/drivers/scsi/scsi_tgt_lib.c b/drivers/scsi/scsi_tgt_lib.c
index a91761c..742e1e3 100644
--- a/drivers/scsi/scsi_tgt_lib.c
+++ b/drivers/scsi/scsi_tgt_lib.c
@@ -359,8 +359,7 @@ static int scsi_tgt_init_cmd(struct scsi_cmnd *cmd, gfp_t gfp_mask)
int count;
cmd->use_sg = rq->nr_phys_segments;
- cmd->request_buffer = scsi_alloc_sgtable(cmd, gfp_mask);
- if (!cmd->request_buffer)
+ if (scsi_alloc_sgtable(cmd, gfp_mask))
return -ENOMEM;
cmd->request_bufflen = rq->data_len;
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 3f47e52..40f7c7c 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -8,7 +8,6 @@
#include <linux/scatterlist.h>
struct request;
-struct scatterlist;
struct Scsi_Host;
struct scsi_device;
@@ -68,8 +67,8 @@ struct scsi_cmnd {
void *request_buffer; /* Actual requested buffer */
/* 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;
unsigned underflow; /* Return error if less than
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);
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 int scsi_dma_map(struct scsi_cmnd *cmd);
extern void scsi_dma_unmap(struct scsi_cmnd *cmd);
#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)
static inline void scsi_set_resid(struct scsi_cmnd *cmd, int resid)
--
1.5.3.GIT
--
Jens Axboe
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
