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IB/srp: add support for indirect tables that don't fit in SRP_CMD
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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>
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David Dillow committed Mar 15, 2011
1 parent 8f26c9f commit c07d424
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Showing 2 changed files with 110 additions and 12 deletions.
117 changes: 105 additions & 12 deletions drivers/infiniband/ulp/srp/ib_srp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,8 @@ MODULE_LICENSE("Dual BSD/GPL");

static unsigned int srp_sg_tablesize;
static unsigned int cmd_sg_entries;
static unsigned int indirect_sg_entries;
static bool allow_ext_sg;
static int topspin_workarounds = 1;

module_param(srp_sg_tablesize, uint, 0444);
Expand All @@ -70,6 +72,14 @@ module_param(cmd_sg_entries, uint, 0444);
MODULE_PARM_DESC(cmd_sg_entries,
"Default number of gather/scatter entries in the SRP command (default is 12, max 255)");

module_param(indirect_sg_entries, uint, 0444);
MODULE_PARM_DESC(indirect_sg_entries,
"Default max number of gather/scatter entries (default is 12, max is " __stringify(SCSI_MAX_SG_CHAIN_SEGMENTS) ")");

module_param(allow_ext_sg, bool, 0444);
MODULE_PARM_DESC(allow_ext_sg,
"Default behavior when there are more than cmd_sg_entries S/G entries after mapping; fails the request when false (default false)");

module_param(topspin_workarounds, int, 0444);
MODULE_PARM_DESC(topspin_workarounds,
"Enable workarounds for Topspin/Cisco SRP target bugs if != 0");
Expand Down Expand Up @@ -446,12 +456,19 @@ static bool srp_change_state(struct srp_target_port *target,

static void srp_free_req_data(struct srp_target_port *target)
{
struct ib_device *ibdev = target->srp_host->srp_dev->dev;
struct srp_request *req;
int i;

for (i = 0, req = target->req_ring; i < SRP_CMD_SQ_SIZE; ++i, ++req) {
kfree(req->fmr_list);
kfree(req->map_page);
if (req->indirect_dma_addr) {
ib_dma_unmap_single(ibdev, req->indirect_dma_addr,
target->indirect_size,
DMA_TO_DEVICE);
}
kfree(req->indirect_desc);
}
}

Expand Down Expand Up @@ -790,7 +807,6 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
struct ib_device *ibdev;
struct srp_map_state state;
struct srp_indirect_buf *indirect_hdr;
dma_addr_t indirect_addr;
u32 table_len;
u8 fmt;

Expand Down Expand Up @@ -841,8 +857,11 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
*/
indirect_hdr = (void *) cmd->add_data;

ib_dma_sync_single_for_cpu(ibdev, req->indirect_dma_addr,
target->indirect_size, DMA_TO_DEVICE);

memset(&state, 0, sizeof(state));
state.desc = indirect_hdr->desc_list;
state.desc = req->indirect_desc;
state.pages = req->map_page;
state.next_fmr = req->fmr_list;

Expand Down Expand Up @@ -872,7 +891,11 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
if (use_fmr == SRP_MAP_ALLOW_FMR && srp_map_finish_fmr(&state, target))
goto backtrack;

/* We've mapped the request, fill in the command buffer.
/* We've mapped the request, now pull as much of the indirect
* descriptor table as we can into the command buffer. If this
* target is not using an external indirect table, we are
* guaranteed to fit into the command, as the SCSI layer won't
* give us more S/G entries than we allow.
*/
req->nfmr = state.nfmr;
if (state.ndesc == 1) {
Expand All @@ -881,27 +904,39 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
*/
struct srp_direct_buf *buf = (void *) cmd->add_data;

*buf = indirect_hdr->desc_list[0];
*buf = req->indirect_desc[0];
goto map_complete;
}

if (unlikely(target->cmd_sg_cnt < state.ndesc &&
!target->allow_ext_sg)) {
shost_printk(KERN_ERR, target->scsi_host,
"Could not fit S/G list into SRP_CMD\n");
return -EIO;
}

count = min(state.ndesc, target->cmd_sg_cnt);
table_len = state.ndesc * sizeof (struct srp_direct_buf);

fmt = SRP_DATA_DESC_INDIRECT;
len = sizeof(struct srp_cmd) + sizeof (struct srp_indirect_buf);
len += table_len;
len += count * sizeof (struct srp_direct_buf);

indirect_addr = req->cmd->dma + sizeof *cmd + sizeof *indirect_hdr;
memcpy(indirect_hdr->desc_list, req->indirect_desc,
count * sizeof (struct srp_direct_buf));

indirect_hdr->table_desc.va = cpu_to_be64(indirect_addr);
indirect_hdr->table_desc.va = cpu_to_be64(req->indirect_dma_addr);
indirect_hdr->table_desc.key = cpu_to_be32(target->rkey);
indirect_hdr->table_desc.len = cpu_to_be32(table_len);
indirect_hdr->len = cpu_to_be32(state.total_len);

if (scmnd->sc_data_direction == DMA_TO_DEVICE)
cmd->data_out_desc_cnt = state.ndesc;
cmd->data_out_desc_cnt = count;
else
cmd->data_in_desc_cnt = state.ndesc;
cmd->data_in_desc_cnt = count;

ib_dma_sync_single_for_device(ibdev, req->indirect_dma_addr, table_len,
DMA_TO_DEVICE);

map_complete:
if (scmnd->sc_data_direction == DMA_TO_DEVICE)
Expand Down Expand Up @@ -1759,6 +1794,14 @@ static ssize_t show_cmd_sg_entries(struct device *dev,
return sprintf(buf, "%u\n", target->cmd_sg_cnt);
}

static ssize_t show_allow_ext_sg(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct srp_target_port *target = host_to_target(class_to_shost(dev));

return sprintf(buf, "%s\n", target->allow_ext_sg ? "true" : "false");
}

static DEVICE_ATTR(id_ext, S_IRUGO, show_id_ext, NULL);
static DEVICE_ATTR(ioc_guid, S_IRUGO, show_ioc_guid, NULL);
static DEVICE_ATTR(service_id, S_IRUGO, show_service_id, NULL);
Expand All @@ -1770,6 +1813,7 @@ static DEVICE_ATTR(zero_req_lim, S_IRUGO, show_zero_req_lim, NULL);
static DEVICE_ATTR(local_ib_port, S_IRUGO, show_local_ib_port, NULL);
static DEVICE_ATTR(local_ib_device, S_IRUGO, show_local_ib_device, NULL);
static DEVICE_ATTR(cmd_sg_entries, S_IRUGO, show_cmd_sg_entries, NULL);
static DEVICE_ATTR(allow_ext_sg, S_IRUGO, show_allow_ext_sg, NULL);

static struct device_attribute *srp_host_attrs[] = {
&dev_attr_id_ext,
Expand All @@ -1783,6 +1827,7 @@ static struct device_attribute *srp_host_attrs[] = {
&dev_attr_local_ib_port,
&dev_attr_local_ib_device,
&dev_attr_cmd_sg_entries,
&dev_attr_allow_ext_sg,
NULL
};

Expand Down Expand Up @@ -1868,6 +1913,8 @@ enum {
SRP_OPT_IO_CLASS = 1 << 7,
SRP_OPT_INITIATOR_EXT = 1 << 8,
SRP_OPT_CMD_SG_ENTRIES = 1 << 9,
SRP_OPT_ALLOW_EXT_SG = 1 << 10,
SRP_OPT_SG_TABLESIZE = 1 << 11,
SRP_OPT_ALL = (SRP_OPT_ID_EXT |
SRP_OPT_IOC_GUID |
SRP_OPT_DGID |
Expand All @@ -1886,6 +1933,8 @@ static const match_table_t srp_opt_tokens = {
{ SRP_OPT_IO_CLASS, "io_class=%x" },
{ SRP_OPT_INITIATOR_EXT, "initiator_ext=%s" },
{ SRP_OPT_CMD_SG_ENTRIES, "cmd_sg_entries=%u" },
{ SRP_OPT_ALLOW_EXT_SG, "allow_ext_sg=%u" },
{ SRP_OPT_SG_TABLESIZE, "sg_tablesize=%u" },
{ SRP_OPT_ERR, NULL }
};

Expand Down Expand Up @@ -2021,6 +2070,23 @@ static int srp_parse_options(const char *buf, struct srp_target_port *target)
target->cmd_sg_cnt = token;
break;

case SRP_OPT_ALLOW_EXT_SG:
if (match_int(args, &token)) {
printk(KERN_WARNING PFX "bad allow_ext_sg parameter '%s'\n", p);
goto out;
}
target->allow_ext_sg = !!token;
break;

case SRP_OPT_SG_TABLESIZE:
if (match_int(args, &token) || token < 1 ||
token > SCSI_MAX_SG_CHAIN_SEGMENTS) {
printk(KERN_WARNING PFX "bad max sg_tablesize parameter '%s'\n", p);
goto out;
}
target->sg_tablesize = token;
break;

default:
printk(KERN_WARNING PFX "unknown parameter or missing value "
"'%s' in target creation request\n", p);
Expand Down Expand Up @@ -2051,6 +2117,8 @@ static ssize_t srp_create_target(struct device *dev,
container_of(dev, struct srp_host, dev);
struct Scsi_Host *target_host;
struct srp_target_port *target;
struct ib_device *ibdev = host->srp_dev->dev;
dma_addr_t dma_addr;
int i, ret;

target_host = scsi_host_alloc(&srp_template,
Expand All @@ -2070,12 +2138,22 @@ static ssize_t srp_create_target(struct device *dev,
target->lkey = host->srp_dev->mr->lkey;
target->rkey = host->srp_dev->mr->rkey;
target->cmd_sg_cnt = cmd_sg_entries;
target->sg_tablesize = indirect_sg_entries ? : cmd_sg_entries;
target->allow_ext_sg = allow_ext_sg;

ret = srp_parse_options(buf, target);
if (ret)
goto err;

target_host->sg_tablesize = target->cmd_sg_cnt;
if (!host->srp_dev->fmr_pool && !target->allow_ext_sg &&
target->cmd_sg_cnt < target->sg_tablesize) {
printk(KERN_WARNING PFX "No FMR pool and no external indirect descriptors, limiting sg_tablesize to cmd_sg_cnt\n");
target->sg_tablesize = target->cmd_sg_cnt;
}

target_host->sg_tablesize = target->sg_tablesize;
target->indirect_size = target->sg_tablesize *
sizeof (struct srp_direct_buf);
target->max_iu_len = sizeof (struct srp_cmd) +
sizeof (struct srp_indirect_buf) +
target->cmd_sg_cnt * sizeof (struct srp_direct_buf);
Expand All @@ -2090,14 +2168,22 @@ static ssize_t srp_create_target(struct device *dev,
GFP_KERNEL);
req->map_page = kmalloc(SRP_FMR_SIZE * sizeof (void *),
GFP_KERNEL);
if (!req->fmr_list || !req->map_page)
req->indirect_desc = kmalloc(target->indirect_size, GFP_KERNEL);
if (!req->fmr_list || !req->map_page || !req->indirect_desc)
goto err_free_mem;

dma_addr = ib_dma_map_single(ibdev, req->indirect_desc,
target->indirect_size,
DMA_TO_DEVICE);
if (ib_dma_mapping_error(ibdev, dma_addr))
goto err_free_mem;

req->indirect_dma_addr = dma_addr;
req->index = i;
list_add_tail(&req->list, &target->free_reqs);
}

ib_query_gid(host->srp_dev->dev, host->port, 0, &target->path.sgid);
ib_query_gid(ibdev, host->port, 0, &target->path.sgid);

shost_printk(KERN_DEBUG, target->scsi_host, PFX
"new target: id_ext %016llx ioc_guid %016llx pkey %04x "
Expand Down Expand Up @@ -2377,6 +2463,13 @@ static int __init srp_init_module(void)
cmd_sg_entries = 255;
}

if (!indirect_sg_entries)
indirect_sg_entries = cmd_sg_entries;
else if (indirect_sg_entries < cmd_sg_entries) {
printk(KERN_WARNING PFX "Bumping up indirect_sg_entries to match cmd_sg_entries (%u)\n", cmd_sg_entries);
indirect_sg_entries = cmd_sg_entries;
}

ib_srp_transport_template =
srp_attach_transport(&ib_srp_transport_functions);
if (!ib_srp_transport_template)
Expand Down
5 changes: 5 additions & 0 deletions drivers/infiniband/ulp/srp/ib_srp.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
};
Expand All @@ -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.
Expand All @@ -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];
Expand Down

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