IB/srp: add support for indirect tables that don't fit in SRP_CMD

This allows us to guarantee the ability to submit up to 8 MB requests
based on the current value of SCSI_MAX_SG_CHAIN_SEGMENTS. While FMR will
usually condense the requests into 8 SG entries, it is imperative that
the target support external tables in case the FMR mapping fails or is
not supported.

We add a safety valve to allow targets without the needed support to
reap the benefits of the large tables, but fail in a manner that lets
the user know that the data didn't make it to the device. The user must
add "allow_ext_sg=1" to the target parameters to indicate that the
target has the needed support.

If indirect_sg_entries is not specified in the modules options, then
the sg_tablesize for the target will default to cmd_sg_entries unless
overridden by the target options.

Signed-off-by: David Dillow <dillowda@ornl.gov>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index b43b5e7acbde..cf696218eeeb 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -117,6 +117,8 @@ struct srp_request {
         struct srp_iu          *cmd;
         struct ib_pool_fmr    **fmr_list;
         u64                    *map_page;
+        struct srp_direct_buf  *indirect_desc;
+        dma_addr_t              indirect_dma_addr;
         short                   nfmr;
         short                   index;
 };
@@ -137,6 +139,8 @@ struct srp_target_port {
         enum srp_target_state   state;
         unsigned int            max_iu_len;
         unsigned int            cmd_sg_cnt;
+        unsigned int            indirect_size;
+        bool                    allow_ext_sg;
 
         /* Everything above this point is used in the hot path of
          * command processing. Try to keep them packed into cachelines.
@@ -151,6 +155,7 @@ struct srp_target_port {
         struct Scsi_Host       *scsi_host;
         char                    target_name[32];
         unsigned int            scsi_id;
+        unsigned int            sg_tablesize;
 
         struct ib_sa_path_rec   path;
         __be16                  orig_dgid[8];