IB/iser: iSER handling of memory for RDMA

This file contains the processing carried over an SG list associated with
a SCSI command such that it can be registered with the IB verbs. The
registration produces a network virtual address (VA) and a remote access
key (RKEY or STAG in iSER spec notation) which are used by the target for
its RDMA operation.

Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Or Gerlitz 2006-05-11 10:03:08 +03:00 committed by Roland Dreier
parent 1cfa0a75db
commit 6461f64ab5

View File

@ -0,0 +1,401 @@
/*
* Copyright (c) 2004, 2005, 2006 Voltaire, Inc. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
* $Id: iser_memory.c 6964 2006-05-07 11:11:43Z ogerlitz $
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <asm/io.h>
#include <asm/scatterlist.h>
#include <linux/scatterlist.h>
#include "iscsi_iser.h"
#define ISER_KMALLOC_THRESHOLD 0x20000 /* 128K - kmalloc limit */
/**
* Decrements the reference count for the
* registered buffer & releases it
*
* returns 0 if released, 1 if deferred
*/
int iser_regd_buff_release(struct iser_regd_buf *regd_buf)
{
struct device *dma_device;
if ((atomic_read(&regd_buf->ref_count) == 0) ||
atomic_dec_and_test(&regd_buf->ref_count)) {
/* if we used the dma mr, unreg is just NOP */
if (regd_buf->reg.rkey != 0)
iser_unreg_mem(&regd_buf->reg);
if (regd_buf->dma_addr) {
dma_device = regd_buf->device->ib_device->dma_device;
dma_unmap_single(dma_device,
regd_buf->dma_addr,
regd_buf->data_size,
regd_buf->direction);
}
/* else this regd buf is associated with task which we */
/* dma_unmap_single/sg later */
return 0;
} else {
iser_dbg("Release deferred, regd.buff: 0x%p\n", regd_buf);
return 1;
}
}
/**
* iser_reg_single - fills registered buffer descriptor with
* registration information
*/
void iser_reg_single(struct iser_device *device,
struct iser_regd_buf *regd_buf,
enum dma_data_direction direction)
{
dma_addr_t dma_addr;
dma_addr = dma_map_single(device->ib_device->dma_device,
regd_buf->virt_addr,
regd_buf->data_size, direction);
BUG_ON(dma_mapping_error(dma_addr));
regd_buf->reg.lkey = device->mr->lkey;
regd_buf->reg.rkey = 0; /* indicate there's no need to unreg */
regd_buf->reg.len = regd_buf->data_size;
regd_buf->reg.va = dma_addr;
regd_buf->dma_addr = dma_addr;
regd_buf->direction = direction;
}
/**
* iser_start_rdma_unaligned_sg
*/
int iser_start_rdma_unaligned_sg(struct iscsi_iser_cmd_task *iser_ctask,
enum iser_data_dir cmd_dir)
{
int dma_nents;
struct device *dma_device;
char *mem = NULL;
struct iser_data_buf *data = &iser_ctask->data[cmd_dir];
unsigned long cmd_data_len = data->data_len;
if (cmd_data_len > ISER_KMALLOC_THRESHOLD)
mem = (void *)__get_free_pages(GFP_NOIO,
long_log2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT);
else
mem = kmalloc(cmd_data_len, GFP_NOIO);
if (mem == NULL) {
iser_err("Failed to allocate mem size %d %d for copying sglist\n",
data->size,(int)cmd_data_len);
return -ENOMEM;
}
if (cmd_dir == ISER_DIR_OUT) {
/* copy the unaligned sg the buffer which is used for RDMA */
struct scatterlist *sg = (struct scatterlist *)data->buf;
int i;
char *p, *from;
for (p = mem, i = 0; i < data->size; i++) {
from = kmap_atomic(sg[i].page, KM_USER0);
memcpy(p,
from + sg[i].offset,
sg[i].length);
kunmap_atomic(from, KM_USER0);
p += sg[i].length;
}
}
sg_init_one(&iser_ctask->data_copy[cmd_dir].sg_single, mem, cmd_data_len);
iser_ctask->data_copy[cmd_dir].buf =
&iser_ctask->data_copy[cmd_dir].sg_single;
iser_ctask->data_copy[cmd_dir].size = 1;
iser_ctask->data_copy[cmd_dir].copy_buf = mem;
dma_device = iser_ctask->iser_conn->ib_conn->device->ib_device->dma_device;
if (cmd_dir == ISER_DIR_OUT)
dma_nents = dma_map_sg(dma_device,
&iser_ctask->data_copy[cmd_dir].sg_single,
1, DMA_TO_DEVICE);
else
dma_nents = dma_map_sg(dma_device,
&iser_ctask->data_copy[cmd_dir].sg_single,
1, DMA_FROM_DEVICE);
BUG_ON(dma_nents == 0);
iser_ctask->data_copy[cmd_dir].dma_nents = dma_nents;
return 0;
}
/**
* iser_finalize_rdma_unaligned_sg
*/
void iser_finalize_rdma_unaligned_sg(struct iscsi_iser_cmd_task *iser_ctask,
enum iser_data_dir cmd_dir)
{
struct device *dma_device;
struct iser_data_buf *mem_copy;
unsigned long cmd_data_len;
dma_device = iser_ctask->iser_conn->ib_conn->device->ib_device->dma_device;
mem_copy = &iser_ctask->data_copy[cmd_dir];
if (cmd_dir == ISER_DIR_OUT)
dma_unmap_sg(dma_device, &mem_copy->sg_single, 1,
DMA_TO_DEVICE);
else
dma_unmap_sg(dma_device, &mem_copy->sg_single, 1,
DMA_FROM_DEVICE);
if (cmd_dir == ISER_DIR_IN) {
char *mem;
struct scatterlist *sg;
unsigned char *p, *to;
unsigned int sg_size;
int i;
/* copy back read RDMA to unaligned sg */
mem = mem_copy->copy_buf;
sg = (struct scatterlist *)iser_ctask->data[ISER_DIR_IN].buf;
sg_size = iser_ctask->data[ISER_DIR_IN].size;
for (p = mem, i = 0; i < sg_size; i++){
to = kmap_atomic(sg[i].page, KM_SOFTIRQ0);
memcpy(to + sg[i].offset,
p,
sg[i].length);
kunmap_atomic(to, KM_SOFTIRQ0);
p += sg[i].length;
}
}
cmd_data_len = iser_ctask->data[cmd_dir].data_len;
if (cmd_data_len > ISER_KMALLOC_THRESHOLD)
free_pages((unsigned long)mem_copy->copy_buf,
long_log2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT);
else
kfree(mem_copy->copy_buf);
mem_copy->copy_buf = NULL;
}
/**
* iser_sg_to_page_vec - Translates scatterlist entries to physical addresses
* and returns the length of resulting physical address array (may be less than
* the original due to possible compaction).
*
* we build a "page vec" under the assumption that the SG meets the RDMA
* alignment requirements. Other then the first and last SG elements, all
* the "internal" elements can be compacted into a list whose elements are
* dma addresses of physical pages. The code supports also the weird case
* where --few fragments of the same page-- are present in the SG as
* consecutive elements. Also, it handles one entry SG.
*/
static int iser_sg_to_page_vec(struct iser_data_buf *data,
struct iser_page_vec *page_vec)
{
struct scatterlist *sg = (struct scatterlist *)data->buf;
dma_addr_t first_addr, last_addr, page;
int start_aligned, end_aligned;
unsigned int cur_page = 0;
unsigned long total_sz = 0;
int i;
/* compute the offset of first element */
page_vec->offset = (u64) sg[0].offset;
for (i = 0; i < data->dma_nents; i++) {
total_sz += sg_dma_len(&sg[i]);
first_addr = sg_dma_address(&sg[i]);
last_addr = first_addr + sg_dma_len(&sg[i]);
start_aligned = !(first_addr & ~PAGE_MASK);
end_aligned = !(last_addr & ~PAGE_MASK);
/* continue to collect page fragments till aligned or SG ends */
while (!end_aligned && (i + 1 < data->dma_nents)) {
i++;
total_sz += sg_dma_len(&sg[i]);
last_addr = sg_dma_address(&sg[i]) + sg_dma_len(&sg[i]);
end_aligned = !(last_addr & ~PAGE_MASK);
}
first_addr = first_addr & PAGE_MASK;
for (page = first_addr; page < last_addr; page += PAGE_SIZE)
page_vec->pages[cur_page++] = page;
}
page_vec->data_size = total_sz;
iser_dbg("page_vec->data_size:%d cur_page %d\n", page_vec->data_size,cur_page);
return cur_page;
}
#define MASK_4K ((1UL << 12) - 1) /* 0xFFF */
#define IS_4K_ALIGNED(addr) ((((unsigned long)addr) & MASK_4K) == 0)
/**
* iser_data_buf_aligned_len - Tries to determine the maximal correctly aligned
* for RDMA sub-list of a scatter-gather list of memory buffers, and returns
* the number of entries which are aligned correctly. Supports the case where
* consecutive SG elements are actually fragments of the same physcial page.
*/
static unsigned int iser_data_buf_aligned_len(struct iser_data_buf *data)
{
struct scatterlist *sg;
dma_addr_t end_addr, next_addr;
int i, cnt;
unsigned int ret_len = 0;
sg = (struct scatterlist *)data->buf;
for (cnt = 0, i = 0; i < data->dma_nents; i++, cnt++) {
/* iser_dbg("Checking sg iobuf [%d]: phys=0x%08lX "
"offset: %ld sz: %ld\n", i,
(unsigned long)page_to_phys(sg[i].page),
(unsigned long)sg[i].offset,
(unsigned long)sg[i].length); */
end_addr = sg_dma_address(&sg[i]) +
sg_dma_len(&sg[i]);
/* iser_dbg("Checking sg iobuf end address "
"0x%08lX\n", end_addr); */
if (i + 1 < data->dma_nents) {
next_addr = sg_dma_address(&sg[i+1]);
/* are i, i+1 fragments of the same page? */
if (end_addr == next_addr)
continue;
else if (!IS_4K_ALIGNED(end_addr)) {
ret_len = cnt + 1;
break;
}
}
}
if (i == data->dma_nents)
ret_len = cnt; /* loop ended */
iser_dbg("Found %d aligned entries out of %d in sg:0x%p\n",
ret_len, data->dma_nents, data);
return ret_len;
}
static void iser_data_buf_dump(struct iser_data_buf *data)
{
struct scatterlist *sg = (struct scatterlist *)data->buf;
int i;
for (i = 0; i < data->size; i++)
iser_err("sg[%d] dma_addr:0x%lX page:0x%p "
"off:%d sz:%d dma_len:%d\n",
i, (unsigned long)sg_dma_address(&sg[i]),
sg[i].page, sg[i].offset,
sg[i].length,sg_dma_len(&sg[i]));
}
static void iser_dump_page_vec(struct iser_page_vec *page_vec)
{
int i;
iser_err("page vec length %d data size %d\n",
page_vec->length, page_vec->data_size);
for (i = 0; i < page_vec->length; i++)
iser_err("%d %lx\n",i,(unsigned long)page_vec->pages[i]);
}
static void iser_page_vec_build(struct iser_data_buf *data,
struct iser_page_vec *page_vec)
{
int page_vec_len = 0;
page_vec->length = 0;
page_vec->offset = 0;
iser_dbg("Translating sg sz: %d\n", data->dma_nents);
page_vec_len = iser_sg_to_page_vec(data,page_vec);
iser_dbg("sg len %d page_vec_len %d\n", data->dma_nents,page_vec_len);
page_vec->length = page_vec_len;
if (page_vec_len * PAGE_SIZE < page_vec->data_size) {
iser_err("page_vec too short to hold this SG\n");
iser_data_buf_dump(data);
iser_dump_page_vec(page_vec);
BUG();
}
}
/**
* iser_reg_rdma_mem - Registers memory intended for RDMA,
* obtaining rkey and va
*
* returns 0 on success, errno code on failure
*/
int iser_reg_rdma_mem(struct iscsi_iser_cmd_task *iser_ctask,
enum iser_data_dir cmd_dir)
{
struct iser_conn *ib_conn = iser_ctask->iser_conn->ib_conn;
struct iser_data_buf *mem = &iser_ctask->data[cmd_dir];
struct iser_regd_buf *regd_buf;
int aligned_len;
int err;
regd_buf = &iser_ctask->rdma_regd[cmd_dir];
aligned_len = iser_data_buf_aligned_len(mem);
if (aligned_len != mem->size) {
iser_err("rdma alignment violation %d/%d aligned\n",
aligned_len, mem->size);
iser_data_buf_dump(mem);
/* allocate copy buf, if we are writing, copy the */
/* unaligned scatterlist, dma map the copy */
if (iser_start_rdma_unaligned_sg(iser_ctask, cmd_dir) != 0)
return -ENOMEM;
mem = &iser_ctask->data_copy[cmd_dir];
}
iser_page_vec_build(mem, ib_conn->page_vec);
err = iser_reg_page_vec(ib_conn, ib_conn->page_vec, &regd_buf->reg);
if (err)
return err;
/* take a reference on this regd buf such that it will not be released *
* (eg in send dto completion) before we get the scsi response */
atomic_inc(&regd_buf->ref_count);
return 0;
}