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authorJens Axboe <jens.axboe@oracle.com>2007-11-15 09:13:11 +0100
committerJens Axboe <jens.axboe@oracle.com>2008-01-28 10:05:27 +0100
commit5ed7959ede0936c55e50421a53f153b17080e876 (patch)
tree52fae9cd4959b7855e37c5dc4d0ce7eb22656cdb /drivers/scsi/scsi_lib.c
parentSG: Move functions to lib/scatterlist.c and add sg chaining allocator helpers (diff)
downloadlinux-5ed7959ede0936c55e50421a53f153b17080e876.tar.xz
linux-5ed7959ede0936c55e50421a53f153b17080e876.zip
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@oracle.com>
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r--drivers/scsi/scsi_lib.c138
1 files changed, 20 insertions, 118 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 4cf902efbdbf..3b5121c4c081 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -739,138 +739,41 @@ 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;
+ sgp = scsi_sg_pools + scsi_sgtable_index(nents);
+ mempool_free(sgl, sgp->pool);
+}
- sgl = mempool_alloc(sgp->pool, gfp_mask);
- if (unlikely(!sgl))
- goto enomem;
+static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
+{
+ struct scsi_host_sg_pool *sgp;
- sg_init_table(sgl, sgp->size);
+ sgp = scsi_sg_pools + scsi_sgtable_index(nents);
+ return mempool_alloc(sgp->pool, gfp_mask);
+}
- /*
- * first loop through, set initial index and return value
- */
- if (!ret)
- ret = sgl;
+int scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
+{
+ int ret;
- /*
- * 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);
+ BUG_ON(!cmd->use_sg);
- /*
- * if we have nothing left, mark the last segment as
- * end-of-list
- */
- if (!left)
- sg_mark_end(&sgl[this - 1]);
+ ret = __sg_alloc_table(&cmd->sg_table, cmd->use_sg, gfp_mask, scsi_sg_alloc);
+ if (unlikely(ret))
+ __sg_free_table(&cmd->sg_table, scsi_sg_free);
- /*
- * 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;
+ 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);
@@ -1120,8 +1023,7 @@ 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;
}