[SCSI] mpt2sas: Create a pool of chain buffer instead of dedicated per IOs

Create a pool of chain buffers, instead of dedicated per IO:
This enahancment is to address memory allocation failure when asking
for more than 2300 IOs per host.   There is just not enough contiquious
DMA physical memory to make one single allocation to hold both message
frames and chain buffers when asking for more than 2300 request. In order
to address this problem we will have to allocate memory for each chain
buffer in a seperate individual memory allocation, placing each chain
element of 128 bytes onto a pool of available chains, which can be
shared amoung all request.
Signed-off-by: Kashyap Desai <kashyap.desai@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 17 insertions, 2 deletions

diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.h b/drivers/scsi/mpt2sas/mpt2sas_base.h
index 63f7a196f42..edf1a028db6 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_base.h
+++ b/drivers/scsi/mpt2sas/mpt2sas_base.h
@@ -419,6 +419,18 @@ enum reset_type {
 };
 
 /**
+ * struct chain_tracker - firmware chain tracker
+ * @chain_buffer: chain buffer
+ * @chain_buffer_dma: physical address
+ * @tracker_list: list of free request (ioc->free_chain_list)
+ */
+struct chain_tracker {
+	void *chain_buffer;
+	dma_addr_t chain_buffer_dma;
+	struct list_head tracker_list;
+};
+
+/**
  * struct request_tracker - firmware request tracker
  * @smid: system message id
  * @scmd: scsi request pointer
@@ -430,6 +442,7 @@ struct request_tracker {
 	u16	smid;
 	struct scsi_cmnd *scmd;
 	u8	cb_idx;
+	struct list_head chain_list;
 	struct list_head tracker_list;
 };
 
@@ -704,8 +717,10 @@ struct MPT2SAS_ADAPTER {
 	wait_queue_head_t reset_wq;
 
 	/* chain */
-	u8		*chain;
-	dma_addr_t	chain_dma;
+	struct chain_tracker *chain_lookup;
+	struct list_head free_chain_list;
+	struct dma_pool *chain_dma_pool;
+	ulong		chain_pages;
 	u16 		max_sges_in_main_message;
 	u16		max_sges_in_chain_message;
 	u16		chains_needed_per_io;