[PATCH 03/18] mg_disk: dequeue and track in-flight request

Tejun Heo
2009-05-08T03:05:32Z

mg_disk has at most single request in flight per device. Till now,
whenever it needs to access the in-flight request it called
elv_next_request(). This patch makes mg_disk track the in-flight
request directly using mg_host->req and dequeue it when processing
starts.

q->queuedata is set to mg_host so that mg_host can be determined
without fetching request from the queue.

[ Impact: dequeue in-flight request, one elv_next_request() per request ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: unsik Kim <donari75@gmail.com>
---
drivers/block/mg_disk.c | 109 +++++++++++++++++++++++++---------------------
1 files changed, 59 insertions(+), 50 deletions(-)

diff --git a/drivers/block/mg_disk.c b/drivers/block/mg_disk.c
index be32388..1ca5d14 100644
--- a/drivers/block/mg_disk.c
+++ b/drivers/block/mg_disk.c
@@ -135,6 +135,7 @@ struct mg_host {
struct device *dev;

struct request_queue *breq;
+ struct request *req;
spinlock_t lock;
struct gendisk *gd;

@@ -171,17 +172,27 @@ struct mg_host {

static void mg_request(struct request_queue *);

+static bool mg_end_request(struct mg_host *host, int err, unsigned int nr_bytes)
+{
+ if (__blk_end_request(host->req, err, nr_bytes))
+ return true;
+
+ host->req = NULL;
+ return false;
+}
+
+static bool mg_end_request_cur(struct mg_host *host, int err)
+{
+ return mg_end_request(host, err, blk_rq_cur_bytes(host->req));
+}
+
static void mg_dump_status(const char *msg, unsigned int stat,
struct mg_host *host)
{
char *name = MG_DISK_NAME;
- struct request *req;

- if (host->breq) {
- req = elv_next_request(host->breq);
- if (req)
- name = req->rq_disk->disk_name;
- }
+ if (host->req)
+ name = host->req->rq_disk->disk_name;

printk(KERN_ERR "%s: %s: status=0x%02x { ", name, msg, stat & 0xff);
if (stat & ATA_BUSY)
@@ -217,13 +228,9 @@ static void mg_dump_status(const char *msg, unsigned int stat,
printk("AddrMarkNotFound ");
printk("}");
if (host->error & (ATA_BBK | ATA_UNC | ATA_IDNF | ATA_AMNF)) {
- if (host->breq) {
- req = elv_next_request(host->breq);
- if (req)
- printk(", sector=%u",
- (unsigned int)blk_rq_pos(req));
- }
-
+ if (host->req)
+ printk(", sector=%u",
+ (unsigned int)blk_rq_pos(host->req));
}
printk("\n");
}
@@ -453,11 +460,10 @@ static int mg_disk_init(struct mg_host *host)

static void mg_bad_rw_intr(struct mg_host *host)
{
- struct request *req = elv_next_request(host->breq);
- if (req != NULL)
- if (++req->errors >= MG_MAX_ERRORS ||
- host->error == MG_ERR_TIMEOUT)
- __blk_end_request_cur(req, -EIO);
+ if (host->req)
+ if (++host->req->errors >= MG_MAX_ERRORS ||
+ host->error == MG_ERR_TIMEOUT)
+ mg_end_request_cur(host, -EIO);
}

static unsigned int mg_out(struct mg_host *host,
@@ -515,7 +521,7 @@ static void mg_read(struct request *req)

outb(MG_CMD_RD_CONF, (unsigned long)host->dev_base +
MG_REG_COMMAND);
- } while (__blk_end_request(req, 0, MG_SECTOR_SIZE));
+ } while (mg_end_request(host, 0, MG_SECTOR_SIZE));
}

static void mg_write(struct request *req)
@@ -545,14 +551,14 @@ static void mg_write(struct request *req)

outb(MG_CMD_WR_CONF, (unsigned long)host->dev_base +
MG_REG_COMMAND);
- } while (__blk_end_request(req, 0, MG_SECTOR_SIZE));
+ } while (mg_end_request(host, 0, MG_SECTOR_SIZE));
}

static void mg_read_intr(struct mg_host *host)
{
+ struct request *req = host->req;
u32 i;
u16 *buff;
- struct request *req;

/* check status */
do {
@@ -571,7 +577,6 @@ static void mg_read_intr(struct mg_host *host)

ok_to_read:
/* get current segment of request */
- req = elv_next_request(host->breq);
buff = (u16 *)req->buffer;

/* read 1 sector */
@@ -585,7 +590,7 @@ ok_to_read:
/* send read confirm */
outb(MG_CMD_RD_CONF, (unsigned long)host->dev_base + MG_REG_COMMAND);

- if (__blk_end_request(req, 0, MG_SECTOR_SIZE)) {
+ if (mg_end_request(host, 0, MG_SECTOR_SIZE)) {
/* set handler if read remains */
host->mg_do_intr = mg_read_intr;
mod_timer(&host->timer, jiffies + 3 * HZ);
@@ -595,14 +600,11 @@ ok_to_read:

static void mg_write_intr(struct mg_host *host)
{
+ struct request *req = host->req;
u32 i, j;
u16 *buff;
- struct request *req;
bool rem;

- /* get current segment of request */
- req = elv_next_request(host->breq);
-
/* check status */
do {
i = inb((unsigned long)host->dev_base + MG_REG_STATUS);
@@ -619,7 +621,7 @@ static void mg_write_intr(struct mg_host *host)
return;

ok_to_write:
- if ((rem = __blk_end_request(req, 0, MG_SECTOR_SIZE))) {
+ if ((rem = mg_end_request(host, 0, MG_SECTOR_SIZE))) {
/* write 1 sector and set handler if remains */
buff = (u16 *)req->buffer;
for (j = 0; j < MG_STORAGE_BUFFER_SIZE >> 1; j++) {
@@ -644,44 +646,47 @@ void mg_times_out(unsigned long data)
{
struct mg_host *host = (struct mg_host *)data;
char *name;
- struct request *req;

spin_lock_irq(&host->lock);

- req = elv_next_request(host->breq);
- if (!req)
+ if (!host->req)
goto out_unlock;

host->mg_do_intr = NULL;

- name = req->rq_disk->disk_name;
+ name = host->req->rq_disk->disk_name;
printk(KERN_DEBUG "%s: timeout\n", name);

host->error = MG_ERR_TIMEOUT;
mg_bad_rw_intr(host);

- mg_request(host->breq);
out_unlock:
+ mg_request(host->breq);
spin_unlock_irq(&host->lock);
}

static void mg_request_poll(struct request_queue *q)
{
- struct request *req;
- struct mg_host *host;
+ struct mg_host *host = q->queuedata;

- while ((req = elv_next_request(q)) != NULL) {
- host = req->rq_disk->private_data;
+ while (1) {
+ if (!host->req) {
+ host->req = elv_next_request(q);
+ if (host->req)
+ blkdev_dequeue_request(host->req);
+ else
+ break;
+ }

- if (unlikely(!blk_fs_request(req))) {
- __blk_end_request_cur(req, -EIO);
+ if (unlikely(!blk_fs_request(host->req))) {
+ mg_end_request_cur(host, -EIO);
continue;
}

- if (rq_data_dir(req) == READ)
- mg_read(req);
+ if (rq_data_dir(host->req) == READ)
+ mg_read(host->req);
else
- mg_write(req);
+ mg_write(host->req);
}
}

@@ -733,16 +738,19 @@ static unsigned int mg_issue_req(struct request *req,
/* This function also called from IRQ context */
static void mg_request(struct request_queue *q)
{
+ struct mg_host *host = q->queuedata;
struct request *req;
- struct mg_host *host;
u32 sect_num, sect_cnt;

while (1) {
- req = elv_next_request(q);
- if (!req)
- return;
-
- host = req->rq_disk->private_data;
+ if (!host->req) {
+ host->req = elv_next_request(q);
+ if (host->req)
+ blkdev_dequeue_request(host->req);
+ else
+ break;
+ }
+ req = host->req;

/* check unwanted request call */
if (host->mg_do_intr)
@@ -762,12 +770,12 @@ static void mg_request(struct request_queue *q)
"%s: bad access: sector=%d, count=%d\n",
req->rq_disk->disk_name,
sect_num, sect_cnt);
- __blk_end_request_cur(req, -EIO);
+ mg_end_request_cur(host, -EIO);
continue;
}

if (unlikely(!blk_fs_request(req))) {
- __blk_end_request_cur(req, -EIO);
+ mg_end_request_cur(host, -EIO);
continue;
}

@@ -981,6 +989,7 @@ static int mg_probe(struct platform_device *plat_dev)
__func__, __LINE__);
goto probe_err_5;
}
+ host->breq->queuedata = host;

/* mflash is random device, thanx for the noop */
elevator_exit(host->breq->elevator);
--
1.6.0.2