[stgt] [PATCH] tgt: Add BSG v4 backstore support to usr/bs_sg.c
Nicholas A. Bellinger
nab at linux-iscsi.org
Thu Jun 17 07:42:08 CEST 2010
From: Nicholas Bellinger <nab at linux-iscsi.org>
This patch adds support for the block layer implementation of the sg v4 interface
(BSG) -> STGT with a new struct backingstore_template bsg_bst sharing code with the
original sg_bst. It adds for new function bs_bsg_cmd_submit() for incoming write I/O
and bs_bsg_cmd_complete() for polling read I/O using include/linux/bsg.h:struct sg_io_v4.
This patch adds BSG specific major checks in bs_sg_open() and for getting max_queue using
SG_GET_COMMAND_Q and calling SG_SET_RESERVED_SIZE following init_sg_device().
So far this has been tested with STGT/iSCSI <-> BSG <-> TCM_Loop SPC-4 iSCSI Target
Port emulation and is able to mkfs, fsck and mount a filesystem from a TCM/IBLOCK
Linux LVM kernel level backstore. This code has also been tested with SG_IO and the
legacy codepath.
Signed-off-by: Nicholas A. Bellinger <nab at linux-iscsi.org>
---
usr/bs_sg.c | 161 +++++++++++++++++++++++++++++++++++++++++++++++++++---
usr/scsi_cmnd.h | 3 +
2 files changed, 155 insertions(+), 9 deletions(-)
diff --git a/usr/bs_sg.c b/usr/bs_sg.c
index bb03d46..e8e3551 100644
--- a/usr/bs_sg.c
+++ b/usr/bs_sg.c
@@ -3,6 +3,9 @@
*
* Copyright (C) 2008 Alexander Nezhinsky <nezhinsky at gmail.com>
*
+ * Added linux/block/bsg.c support using struct sg_io_v4.
+ * Copyright (C) 2010 Nicholas A. Bellinger <nab at linux-iscsi.org>
+ *
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2 of the
@@ -33,6 +36,7 @@
#include <sys/stat.h>
#include <sys/epoll.h>
#include <scsi/sg.h>
+#include <linux/bsg.h>
#include "list.h"
#include "util.h"
@@ -45,6 +49,14 @@
#define BS_SG_TIMEOUT 2000
#define BS_SG_SHIFT 9
+//#define BSG_DEBUG_IO
+
+#ifdef BSG_DEBUG_IO
+#define BSG_IO(x...) eprintf(x)
+#else
+#define BSG_IO(x...)
+#endif
+
static int graceful_read(int fd, void *p_read, int to_read)
{
int err;
@@ -107,7 +119,7 @@ static int bs_sg_rw(int host_no, struct scsi_cmd *cmd)
return SAM_STAT_CHECK_CONDITION;
}
-static void set_cmd_failed(struct scsi_cmd *cmd)
+static int set_cmd_failed(struct scsi_cmd *cmd)
{
int result = SAM_STAT_CHECK_CONDITION;
uint16_t asc = ASC_READ_ERROR;
@@ -115,6 +127,52 @@ static void set_cmd_failed(struct scsi_cmd *cmd)
scsi_set_result(cmd, result);
sense_data_build(cmd, key, asc);
+
+ return result;
+}
+
+static int bs_bsg_cmd_submit(struct scsi_cmd *cmd)
+{
+ struct scsi_lu *dev = cmd->dev;
+ int fd = dev->fd;
+ struct sg_io_v4 *io_hdr = &cmd->cmd_bsg_hdr;
+ int err = 0;
+ /*
+ * Following linux/include/linux/bsg.h
+ */
+ /* [i] 'Q' to differentiate from v3 */
+ io_hdr->guard = 'Q';
+ io_hdr->protocol = BSG_PROTOCOL_SCSI;
+ io_hdr->subprotocol = BSG_SUB_PROTOCOL_SCSI_CMD;
+ io_hdr->request_len = cmd->scb_len;
+ io_hdr->request = (unsigned long )cmd->scb;
+
+ io_hdr->dout_xfer_len = scsi_get_out_length(cmd);
+ io_hdr->dout_xferp = (unsigned long)scsi_get_out_buffer(cmd);
+ io_hdr->din_xfer_len = scsi_get_in_length(cmd);
+ io_hdr->din_xferp = (unsigned long)scsi_get_in_buffer(cmd);
+
+ io_hdr->max_response_len = sizeof(cmd->sense_buffer);
+ /* SCSI: (auto)sense data */
+ io_hdr->response = (unsigned long)cmd->sense_buffer;
+ /* Using the same 2000 millisecond timeout.. */
+ io_hdr->timeout = BS_SG_TIMEOUT;
+ /* [i->o] unused internally */
+ io_hdr->usr_ptr = (unsigned long)cmd;
+ BSG_IO("[%d] Set io_hdr->usr_ptr from cmd: %p\n", getpid(), cmd);
+ /* Bsg does Q_AT_HEAD by default */
+ io_hdr->flags |= BSG_FLAG_Q_AT_TAIL;
+
+ BSG_IO("[%d] Calling graceful_write for CDB: 0x%02x\n", getpid(), cmd->scb[0]);
+ err = graceful_write(fd, &cmd->cmd_bsg_hdr, sizeof(struct sg_io_v4));
+ if (!err)
+ set_cmd_async(cmd);
+ else {
+ eprintf("failed to start cmd 0x%p\n", cmd);
+ return set_cmd_failed(cmd);
+ }
+
+ return 0;
}
static int bs_sg_cmd_submit(struct scsi_cmd *cmd)
@@ -156,11 +214,47 @@ static int bs_sg_cmd_submit(struct scsi_cmd *cmd)
set_cmd_async(cmd);
else {
eprintf("failed to start cmd 0x%p\n", cmd);
- set_cmd_failed(cmd);
+ return set_cmd_failed(cmd);
}
return 0;
}
+static void bs_bsg_cmd_complete(int fd, int events, void *data)
+{
+ struct sg_io_v4 io_hdr;
+ struct scsi_cmd *cmd;
+ int err;
+
+ BSG_IO("[%d] bs_bsg_cmd_complete() called!\n", getpid());
+ memset(&io_hdr, 0, sizeof(io_hdr));
+ /* [i] 'Q' to differentiate from v3 */
+ io_hdr.guard = 'Q';
+
+ err = graceful_read(fd, &io_hdr, sizeof(io_hdr));
+ if (err)
+ return;
+
+ cmd = (struct scsi_cmd *)(unsigned long)io_hdr.usr_ptr;
+ BSG_IO("BSG Using cmd: %p for io_hdr.usr_ptr\n", cmd);
+ /*
+ * Check SCSI: command completion status
+ * */
+ if (!io_hdr.device_status) {
+ scsi_set_out_resid(cmd, io_hdr.dout_resid);
+ scsi_set_in_resid(cmd, io_hdr.din_resid);
+ } else {
+ /*
+ * NAB: Used by linux/block/bsg.c:bsg_ioctl(), is this
+ * right..?
+ */
+ cmd->sense_len = SCSI_SENSE_BUFFERSIZE;
+ scsi_set_out_resid_by_actual(cmd, 0);
+ scsi_set_in_resid_by_actual(cmd, 0);
+ }
+ BSG_IO("[%d] BSG() Calling cmd->scsi_cmd_done()\n", getpid());
+ cmd->scsi_cmd_done(cmd, io_hdr.device_status);
+}
+
static void bs_sg_cmd_complete(int fd, int events, void *data)
{
struct sg_io_hdr io_hdr;
@@ -197,10 +291,41 @@ static int chk_sg_device(char *path)
return -1;
}
- if (S_ISCHR(st.st_mode) && major(st.st_rdev) == SCSI_GENERIC_MAJOR)
+ if (!S_ISCHR(st.st_mode)) {
+ eprintf("Not a character device: %s\n", path);
+ return -1;
+ }
+
+ /* Check for SG_IO major first.. */
+ if (major(st.st_rdev) == SCSI_GENERIC_MAJOR)
return 0;
- else
+
+ /* This is not yet defined in include/linux/major.h.. */
+ if (major(st.st_rdev) == 254)
+ return 1;
+
+ return -1;
+}
+
+static int init_bsg_device(int fd)
+{
+ int t, err;
+
+ err = ioctl(fd, SG_GET_COMMAND_Q, &t);
+ if (err < 0) {
+ eprintf("SG_GET_COMMAND_Q for bsd failed: %d\n", err);
return -1;
+ }
+ eprintf("bsg: Using max_queue: %d\n", t);
+
+ t = BS_SG_RESVD_SZ;
+ err = ioctl(fd, SG_SET_RESERVED_SIZE, &t);
+ if (err < 0) {
+ eprintf("SG_SET_RESERVED_SIZE errno: %d\n", errno);
+ return -1;
+ }
+
+ return 0;
}
static int init_sg_device(int fd)
@@ -241,10 +366,11 @@ static int bs_sg_init(struct scsi_lu *lu)
static int bs_sg_open(struct scsi_lu *lu, char *path, int *fd, uint64_t *size)
{
- int sg_fd, err;
+ void (*cmd_complete)(int, int, void *) = NULL;
+ int sg_fd, err, bsg = 0;
- err = chk_sg_device(path);
- if (err) {
+ bsg = chk_sg_device(path);
+ if (bsg < 0) {
eprintf("Not recognized %s as an SG device\n", path);
return -EINVAL;
}
@@ -255,13 +381,19 @@ static int bs_sg_open(struct scsi_lu *lu, char *path, int *fd, uint64_t *size)
return sg_fd;
}
- err = init_sg_device(sg_fd);
+ if (bsg) {
+ cmd_complete = &bs_bsg_cmd_complete;
+ err = init_bsg_device(sg_fd);
+ } else {
+ cmd_complete = bs_sg_cmd_complete;
+ err = init_sg_device(sg_fd);
+ }
if (err) {
eprintf("Failed to initialize sg device %s\n", path);
return err;
}
- err = tgt_event_add(sg_fd, EPOLLIN, bs_sg_cmd_complete, NULL);
+ err = tgt_event_add(sg_fd, EPOLLIN, cmd_complete, NULL);
if (err) {
eprintf("Failed to add sg device event %s\n", path);
return err;
@@ -300,6 +432,16 @@ static struct backingstore_template sg_bst = {
.bs_cmd_done = bs_sg_cmd_done,
};
+static struct backingstore_template bsg_bst = {
+ .bs_name = "bsg",
+ .bs_datasize = 0,
+ .bs_init = bs_sg_init,
+ .bs_open = bs_sg_open,
+ .bs_close = bs_sg_close,
+ .bs_cmd_submit = bs_bsg_cmd_submit,
+ .bs_cmd_done = bs_sg_cmd_done,
+};
+
static struct device_type_template sg_template = {
.type = TYPE_PT,
.lu_init = bs_sg_lu_init,
@@ -313,5 +455,6 @@ static struct device_type_template sg_template = {
__attribute__((constructor)) static void bs_sg_constructor(void)
{
register_backingstore_template(&sg_bst);
+ register_backingstore_template(&bsg_bst);
device_type_register(&sg_template);
}
diff --git a/usr/scsi_cmnd.h b/usr/scsi_cmnd.h
index fc4861a..67a46c3 100644
--- a/usr/scsi_cmnd.h
+++ b/usr/scsi_cmnd.h
@@ -18,6 +18,7 @@ struct scsi_data_buffer {
};
#include <scsi/sg.h>
+#include <linux/bsg.h>
struct scsi_cmd {
struct target *c_target;
@@ -35,6 +36,8 @@ struct scsi_cmd {
struct scsi_data_buffer out_sdb;
/* Used for bs_sg.c:bs_bs_cmd_submit() */
struct sg_iovec cmd_sg_iovec;
+ /* used for bs_sg.c:bs_bsg_cmd_submit() */
+ struct sg_io_v4 cmd_bsg_hdr;
uint64_t cmd_itn_id;
uint64_t offset;
--
1.5.6.5
--
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