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path: root/drivers/scsi/scsi_lib.c
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Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r--drivers/scsi/scsi_lib.c74
1 files changed, 18 insertions, 56 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 4560713ecb14..e1c7eebfe907 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -8,6 +8,7 @@
*/
#include <linux/bio.h>
+#include <linux/bitops.h>
#include <linux/blkdev.h>
#include <linux/completion.h>
#include <linux/kernel.h>
@@ -34,13 +35,6 @@
#define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
#define SG_MEMPOOL_SIZE 2
-/*
- * 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.
- */
-#define SCSI_MAX_SG_SEGMENTS 128
-
struct scsi_host_sg_pool {
size_t size;
char *name;
@@ -48,19 +42,26 @@ struct scsi_host_sg_pool {
mempool_t *pool;
};
-#define SP(x) { x, "sgpool-" #x }
+#define SP(x) { x, "sgpool-" __stringify(x) }
+#if (SCSI_MAX_SG_SEGMENTS < 32)
+#error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater)
+#endif
static struct scsi_host_sg_pool scsi_sg_pools[] = {
SP(8),
SP(16),
-#if (SCSI_MAX_SG_SEGMENTS > 16)
- SP(32),
#if (SCSI_MAX_SG_SEGMENTS > 32)
- SP(64),
+ SP(32),
#if (SCSI_MAX_SG_SEGMENTS > 64)
+ SP(64),
+#if (SCSI_MAX_SG_SEGMENTS > 128)
SP(128),
+#if (SCSI_MAX_SG_SEGMENTS > 256)
+#error SCSI_MAX_SG_SEGMENTS is too large (256 MAX)
#endif
#endif
#endif
+#endif
+ SP(SCSI_MAX_SG_SEGMENTS)
};
#undef SP
@@ -692,42 +693,16 @@ static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
return NULL;
}
-/*
- * Like SCSI_MAX_SG_SEGMENTS, but for archs that have sg chaining. This limit
- * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
- */
-#define SCSI_MAX_SG_CHAIN_SEGMENTS 2048
-
static inline unsigned int scsi_sgtable_index(unsigned short nents)
{
unsigned int index;
- switch (nents) {
- case 1 ... 8:
+ BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
+
+ if (nents <= 8)
index = 0;
- break;
- case 9 ... 16:
- index = 1;
- break;
-#if (SCSI_MAX_SG_SEGMENTS > 16)
- case 17 ... 32:
- index = 2;
- break;
-#if (SCSI_MAX_SG_SEGMENTS > 32)
- case 33 ... 64:
- index = 3;
- break;
-#if (SCSI_MAX_SG_SEGMENTS > 64)
- case 65 ... 128:
- index = 4;
- break;
-#endif
-#endif
-#endif
- default:
- printk(KERN_ERR "scsi: bad segment count=%d\n", nents);
- BUG();
- }
+ else
+ index = get_count_order(nents) - 3;
return index;
}
@@ -1603,20 +1578,7 @@ struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
* this limit is imposed by hardware restrictions
*/
blk_queue_max_hw_segments(q, shost->sg_tablesize);
-
- /*
- * In the future, sg chaining support will be mandatory and this
- * ifdef can then go away. Right now we don't have all archs
- * converted, so better keep it safe.
- */
-#ifdef ARCH_HAS_SG_CHAIN
- if (shost->use_sg_chaining)
- blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
- else
- blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
-#else
- blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
-#endif
+ blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
blk_queue_max_sectors(q, shost->max_sectors);
blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));