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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.c238
1 files changed, 185 insertions, 53 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 207f1aa08869..aac8a02cbe80 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -17,6 +17,7 @@
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/hardirq.h>
+#include <linux/scatterlist.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
@@ -33,35 +34,34 @@
#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;
+ char *name;
struct kmem_cache *slab;
mempool_t *pool;
};
-#if (SCSI_MAX_PHYS_SEGMENTS < 32)
-#error SCSI_MAX_PHYS_SEGMENTS is too small
-#endif
-
-#define SP(x) { x, "sgpool-" #x }
+#define SP(x) { x, "sgpool-" #x }
static struct scsi_host_sg_pool scsi_sg_pools[] = {
SP(8),
SP(16),
+#if (SCSI_MAX_SG_SEGMENTS > 16)
SP(32),
-#if (SCSI_MAX_PHYS_SEGMENTS > 32)
+#if (SCSI_MAX_SG_SEGMENTS > 32)
SP(64),
-#if (SCSI_MAX_PHYS_SEGMENTS > 64)
+#if (SCSI_MAX_SG_SEGMENTS > 64)
SP(128),
-#if (SCSI_MAX_PHYS_SEGMENTS > 128)
- SP(256),
-#if (SCSI_MAX_PHYS_SEGMENTS > 256)
-#error SCSI_MAX_PHYS_SEGMENTS is too large
-#endif
#endif
#endif
#endif
-};
+};
#undef SP
static void scsi_run_queue(struct request_queue *q);
@@ -289,14 +289,16 @@ static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
struct request_queue *q = rq->q;
int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned int data_len = bufflen, len, bytes, off;
+ struct scatterlist *sg;
struct page *page;
struct bio *bio = NULL;
int i, err, nr_vecs = 0;
- for (i = 0; i < nsegs; i++) {
- page = sgl[i].page;
- off = sgl[i].offset;
- len = sgl[i].length;
+ for_each_sg(sgl, sg, nsegs, i) {
+ page = sg->page;
+ off = sg->offset;
+ len = sg->length;
+ data_len += len;
while (len > 0 && data_len > 0) {
/*
@@ -695,56 +697,170 @@ static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
return NULL;
}
-struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
-{
- struct scsi_host_sg_pool *sgp;
- struct scatterlist *sgl;
+/*
+ * 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
- BUG_ON(!cmd->use_sg);
+static inline unsigned int scsi_sgtable_index(unsigned short nents)
+{
+ unsigned int index;
- switch (cmd->use_sg) {
+ switch (nents) {
case 1 ... 8:
- cmd->sglist_len = 0;
+ index = 0;
break;
case 9 ... 16:
- cmd->sglist_len = 1;
+ index = 1;
break;
+#if (SCSI_MAX_SG_SEGMENTS > 16)
case 17 ... 32:
- cmd->sglist_len = 2;
+ index = 2;
break;
-#if (SCSI_MAX_PHYS_SEGMENTS > 32)
+#if (SCSI_MAX_SG_SEGMENTS > 32)
case 33 ... 64:
- cmd->sglist_len = 3;
+ index = 3;
break;
-#if (SCSI_MAX_PHYS_SEGMENTS > 64)
+#if (SCSI_MAX_SG_SEGMENTS > 64)
case 65 ... 128:
- cmd->sglist_len = 4;
- break;
-#if (SCSI_MAX_PHYS_SEGMENTS > 128)
- case 129 ... 256:
- cmd->sglist_len = 5;
+ index = 4;
break;
#endif
#endif
#endif
default:
- return NULL;
+ printk(KERN_ERR "scsi: bad segment count=%d\n", nents);
+ BUG();
}
- sgp = scsi_sg_pools + cmd->sglist_len;
- sgl = mempool_alloc(sgp->pool, gfp_mask);
- return sgl;
+ return index;
+}
+
+struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
+{
+ 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;
+
+ memset(sgl, 0, sizeof(*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);
+
+ /*
+ * 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;
+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 scatterlist *sgl, int index)
+void scsi_free_sgtable(struct scsi_cmnd *cmd)
{
+ struct scatterlist *sgl = cmd->request_buffer;
struct scsi_host_sg_pool *sgp;
- BUG_ON(index >= SG_MEMPOOL_NR);
+ /*
+ * 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);
- sgp = scsi_sg_pools + index;
mempool_free(sgl, sgp->pool);
}
@@ -770,7 +886,7 @@ EXPORT_SYMBOL(scsi_free_sgtable);
static void scsi_release_buffers(struct scsi_cmnd *cmd)
{
if (cmd->use_sg)
- scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
+ scsi_free_sgtable(cmd);
/*
* Zero these out. They now point to freed memory, and it is
@@ -984,7 +1100,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
static int scsi_init_io(struct scsi_cmnd *cmd)
{
struct request *req = cmd->request;
- struct scatterlist *sgpnt;
int count;
/*
@@ -997,14 +1112,13 @@ static int scsi_init_io(struct scsi_cmnd *cmd)
/*
* If sg table allocation fails, requeue request later.
*/
- sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
- if (unlikely(!sgpnt)) {
+ cmd->request_buffer = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
+ if (unlikely(!cmd->request_buffer)) {
scsi_unprep_request(req);
return BLKPREP_DEFER;
}
req->buffer = NULL;
- cmd->request_buffer = (char *) sgpnt;
if (blk_pc_request(req))
cmd->request_bufflen = req->data_len;
else
@@ -1529,8 +1643,25 @@ struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
if (!q)
return NULL;
+ /*
+ * this limit is imposed by hardware restrictions
+ */
blk_queue_max_hw_segments(q, shost->sg_tablesize);
- blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
+
+ /*
+ * 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_sectors(q, shost->max_sectors);
blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
blk_queue_segment_boundary(q, shost->dma_boundary);
@@ -2193,18 +2324,19 @@ EXPORT_SYMBOL_GPL(scsi_target_unblock);
*
* Returns virtual address of the start of the mapped page
*/
-void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
+void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
size_t *offset, size_t *len)
{
int i;
size_t sg_len = 0, len_complete = 0;
+ struct scatterlist *sg;
struct page *page;
WARN_ON(!irqs_disabled());
- for (i = 0; i < sg_count; i++) {
+ for_each_sg(sgl, sg, sg_count, i) {
len_complete = sg_len; /* Complete sg-entries */
- sg_len += sg[i].length;
+ sg_len += sg->length;
if (sg_len > *offset)
break;
}
@@ -2218,10 +2350,10 @@ void *scsi_kmap_atomic_sg(struct scatterlist *sg, int sg_count,
}
/* Offset starting from the beginning of first page in this sg-entry */
- *offset = *offset - len_complete + sg[i].offset;
+ *offset = *offset - len_complete + sg->offset;
/* Assumption: contiguous pages can be accessed as "page + i" */
- page = nth_page(sg[i].page, (*offset >> PAGE_SHIFT));
+ page = nth_page(sg->page, (*offset >> PAGE_SHIFT));
*offset &= ~PAGE_MASK;
/* Bytes in this sg-entry from *offset to the end of the page */