diff options
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 209 | ||||
| -rw-r--r-- | include/scsi/scsi.h | 7 | ||||
| -rw-r--r-- | include/scsi/scsi_cmnd.h | 1 |
3 files changed, 163 insertions, 54 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 7e1dcc57f11..c75cb6ad6d9 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -36,33 +36,19 @@ 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), SP(32), -#if (SCSI_MAX_PHYS_SEGMENTS > 32) SP(64), -#if (SCSI_MAX_PHYS_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); @@ -698,45 +684,126 @@ 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; +/* + * 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 - BUG_ON(!cmd->use_sg); +/* + * 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 - switch (cmd->use_sg) { +static inline unsigned int scsi_sgtable_index(unsigned short nents) +{ + unsigned int index; + + switch (nents) { case 1 ... 8: - cmd->sglist_len = 0; + index = 0; break; case 9 ... 16: - cmd->sglist_len = 1; + index = 1; break; case 17 ... 32: - cmd->sglist_len = 2; + index = 2; break; -#if (SCSI_MAX_PHYS_SEGMENTS > 32) case 33 ... 64: - cmd->sglist_len = 3; + index = 3; break; -#if (SCSI_MAX_PHYS_SEGMENTS > 64) - case 65 ... 128: - cmd->sglist_len = 4; + case 65 ... SCSI_MAX_SG_SEGMENTS: + index = 4; break; -#if (SCSI_MAX_PHYS_SEGMENTS > 128) - case 129 ... 256: - cmd->sglist_len = 5; - 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) { + cmd->sglist_len = index; + 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); @@ -748,6 +815,42 @@ void scsi_free_sgtable(struct scsi_cmnd *cmd) BUG_ON(cmd->sglist_len >= 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 + cmd->sglist_len; mempool_free(sgl, sgp->pool); } @@ -988,7 +1091,6 @@ 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; /* @@ -1001,14 +1103,13 @@ 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 @@ -1533,8 +1634,22 @@ 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 + blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_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); diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h index 9f8f80ab0c8..702fcfeb37f 100644 --- a/include/scsi/scsi.h +++ b/include/scsi/scsi.h @@ -11,13 +11,6 @@ #include <linux/types.h> /* - * The maximum sg list length SCSI can cope with - * (currently must be a power of 2 between 32 and 256) - */ -#define SCSI_MAX_PHYS_SEGMENTS MAX_PHYS_SEGMENTS - - -/* * SCSI command lengths */ diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h index a5439a4b8f9..4a5fa2d1c44 100644 --- a/include/scsi/scsi_cmnd.h +++ b/include/scsi/scsi_cmnd.h @@ -70,6 +70,7 @@ struct scsi_cmnd { /* These elements define the operation we ultimately want to perform */ unsigned short use_sg; /* Number of pieces of scatter-gather */ unsigned short sglist_len; /* size of malloc'd scatter-gather list */ + unsigned short __use_sg; unsigned underflow; /* Return error if less than this amount is transferred */ |