[PATCH 2/3] SG: Convert SCSI to use scatterlist helpers for sg chaining

Boaz Harrosh
2007-12-20T14:05:00Z

From: Jens Axboe <jens.axboe@oracle.com>

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
drivers/scsi/libsrp.c | 2 +-
drivers/scsi/scsi_error.c | 4 +-
drivers/scsi/scsi_lib.c | 150 +++++-------------------------------------
drivers/usb/storage/isd200.c | 4 +-
include/scsi/scsi_cmnd.h | 9 +--
5 files changed, 24 insertions(+), 145 deletions(-)

diff --git a/drivers/scsi/libsrp.c b/drivers/scsi/libsrp.c
index 8a8562a..b81350d 100644
--- a/drivers/scsi/libsrp.c
+++ b/drivers/scsi/libsrp.c
@@ -427,7 +427,7 @@ int srp_cmd_queue(struct Scsi_Host *shost, struct srp_cmd *cmd, void *info,
sc->SCp.ptr = info;
memcpy(sc->cmnd, cmd->cdb, MAX_COMMAND_SIZE);
sc->sdb.length = len;
- sc->sdb.sglist = (void *) (unsigned long) addr;
+ sc->sdb.sgt.sgl = (void *) (unsigned long) addr;
sc->tag = tag;
err = scsi_tgt_queue_command(sc, itn_id, (struct scsi_lun *)&cmd->lun,
cmd->tag);
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 5c8ba6a..1fd2a8c 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -629,9 +629,9 @@ void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
sizeof(scmd->sense_buffer), sense_bytes);
sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
scmd->sdb.length);
- scmd->sdb.sglist = &ses->sense_sgl;
+ scmd->sdb.sgt.sgl = &ses->sense_sgl;
scmd->sc_data_direction = DMA_FROM_DEVICE;
- scmd->sdb.sg_count = 1;
+ scmd->sdb.sgt.nents = 1;
memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
scmd->cmnd[0] = REQUEST_SENSE;
scmd->cmnd[4] = scmd->sdb.length;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index a6aae56..c7107f1 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -750,136 +750,15 @@ static inline unsigned int scsi_sgtable_index(unsigned short nents)
return index;
}

-static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb,
- unsigned short sg_count, gfp_t gfp_mask)
+static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
{
- struct scsi_host_sg_pool *sgp;
- struct scatterlist *sgl, *prev, *ret;
- unsigned int index;
- int this, left;
-
- left = sg_count;
- 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;
-
- 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.
- */
- sdb->alloc_sg_count = sdb->sg_count = sg_count;
- sdb->sglist = ret;
- return 0;
-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 -ENOMEM;
+ return mempool_alloc(scsi_sg_pools[scsi_sgtable_index(nents)].pool,
+ gfp_mask);
}

-static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
+static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
{
- struct scatterlist *sgl = sdb->sglist;
- struct scsi_host_sg_pool *sgp;
-
- /*
- * if this is the biggest size sglist, check if we have
- * chained parts we need to free
- */
- if (sdb->alloc_sg_count > SCSI_MAX_SG_SEGMENTS) {
- unsigned short this, left;
- struct scatterlist *next;
- unsigned int index;
-
- left = sdb->alloc_sg_count - (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 = sdb->sglist;
- sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
- } else
- sgp = scsi_sg_pools + scsi_sgtable_index(sdb->alloc_sg_count);
-
- mempool_free(sgl, sgp->pool);
+ mempool_free(sgl, scsi_sg_pools[scsi_sgtable_index(nents)].pool);
}

/*
@@ -901,15 +780,15 @@ static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
*/
void scsi_release_buffers(struct scsi_cmnd *cmd)
{
- if (cmd->sdb.sglist)
- scsi_free_sgtable(&cmd->sdb);
+ if (cmd->sdb.sgt.sgl)
+ __sg_free_table(&cmd->sdb.sgt, scsi_sg_free);

memset(&cmd->sdb, 0, sizeof(cmd->sdb));

if (scsi_bidi_cmnd(cmd)) {
struct scsi_data_buffer *bidi_sdb =
cmd->request->next_rq->special;
- scsi_free_sgtable(bidi_sdb);
+ __sg_free_table(&bidi_sdb->sgt, scsi_sg_free);
kmem_cache_free(scsi_bidi_sdb_cache, bidi_sdb);
cmd->request->next_rq->special = NULL;
}
@@ -1135,9 +1014,12 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
gfp_t gfp_mask)
{
- int count;
+ int count, ret;

- if (scsi_alloc_sgtable(sdb, req->nr_phys_segments, gfp_mask)) {
+ ret = __sg_alloc_table(&sdb->sgt, req->nr_phys_segments, gfp_mask,
+ scsi_sg_alloc);
+ if (unlikely(ret)) {
+ __sg_free_table(&sdb->sgt, scsi_sg_free);
return BLKPREP_DEFER;
}

@@ -1151,9 +1033,9 @@ static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
* Next, walk the list, and fill in the addresses and sizes of
* each segment.
*/
- count = blk_rq_map_sg(req->q, req, sdb->sglist);
- BUG_ON(count > sdb->sg_count);
- sdb->sg_count = count;
+ count = blk_rq_map_sg(req->q, req, sdb->sgt.sgl);
+ BUG_ON(count > sdb->sgt.nents);
+ sdb->sgt.nents = count;
return BLKPREP_OK;
}

diff --git a/drivers/usb/storage/isd200.c b/drivers/usb/storage/isd200.c
index 2d9a32b..0214ddb 100644
--- a/drivers/usb/storage/isd200.c
+++ b/drivers/usb/storage/isd200.c
@@ -415,9 +415,9 @@ static void isd200_set_srb(struct isd200_info *info,
sg_init_one(&info->sg, buff, bufflen);

srb->sc_data_direction = dir;
- srb->sdb.sglist = buff ? &info->sg : NULL;
+ srb->sdb.sgt.sgl = buff ? &info->sg : NULL;
srb->sdb.length = bufflen;
- srb->sdb.sg_count = buff ? 1 : 0;
+ srb->sdb.sgt.nents = buff ? 1 : 0;
}

static void isd200_srb_set_bufflen(struct scsi_cmnd *srb, unsigned bufflen)
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index cd2851a..9933bbe 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -8,16 +8,13 @@
#include <linux/timer.h>
#include <linux/scatterlist.h>

-struct scatterlist;
struct Scsi_Host;
struct scsi_device;

struct scsi_data_buffer {
- struct scatterlist *sglist;
+ struct sg_table sgt;
unsigned length;
int resid;
- unsigned short sg_count;
- unsigned short alloc_sg_count; /* private to scsi_lib */
};

/* embedded in scsi_cmnd */
@@ -136,12 +133,12 @@ extern void scsi_dma_unmap(struct scsi_cmnd *cmd);

static inline unsigned scsi_sg_count(struct scsi_cmnd *cmd)
{
- return cmd->sdb.sg_count;
+ return cmd->sdb.sgt.nents;
}

static inline struct scatterlist *scsi_sglist(struct scsi_cmnd *cmd)
{
- return cmd->sdb.sglist;
+ return cmd->sdb.sgt.sgl;
}

static inline unsigned scsi_bufflen(struct scsi_cmnd *cmd)
--
1.5.3.3