[PATCH 02/15] blktrans: remove mtd_blkcore_priv and switch to per device queue and thread

Maxim Levitsky
2010-02-22T18:40:04Z

This is the biggest change. To make hotplug possible, and this layer clean,
the mtd_blktrans_dev now contains everything for a single mtd block translation device.
Also removed some very old leftovers

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
---
drivers/mtd/mtd_blkdevs.c | 124 ++++++++++++++++++++----------------------
include/linux/mtd/blktrans.h | 10 ++--
2 files changed, 63 insertions(+), 71 deletions(-)

diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 2f8c202..6a57262 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -14,7 +14,6 @@
#include <linux/mtd/mtd.h>
#include <linux/blkdev.h>
#include <linux/blkpg.h>
-#include <linux/freezer.h>
#include <linux/spinlock.h>
#include <linux/hdreg.h>
#include <linux/init.h>
@@ -26,11 +25,6 @@

static LIST_HEAD(blktrans_majors);

-struct mtd_blkcore_priv {
- struct task_struct *thread;
- struct request_queue *rq;
- spinlock_t queue_lock;
-};

static int do_blktrans_request(struct mtd_blktrans_ops *tr,
struct mtd_blktrans_dev *dev,
@@ -61,7 +55,6 @@ static int do_blktrans_request(struct mtd_blktrans_ops *tr,
return -EIO;
rq_flush_dcache_pages(req);
return 0;
-
case WRITE:
if (!tr->writesect)
return -EIO;
@@ -71,7 +64,6 @@ static int do_blktrans_request(struct mtd_blktrans_ops *tr,
if (tr->writesect(dev, block, buf))
return -EIO;
return 0;
-
default:
printk(KERN_NOTICE "Unknown request %u\n", rq_data_dir(req));
return -EIO;
@@ -80,14 +72,13 @@ static int do_blktrans_request(struct mtd_blktrans_ops *tr,

static int mtd_blktrans_thread(void *arg)
{
- struct mtd_blktrans_ops *tr = arg;
- struct request_queue *rq = tr->blkcore_priv->rq;
+ struct mtd_blktrans_dev *dev = arg;
+ struct request_queue *rq = dev->rq;
struct request *req = NULL;

spin_lock_irq(rq->queue_lock);

while (!kthread_should_stop()) {
- struct mtd_blktrans_dev *dev;
int res;

if (!req && !(req = blk_fetch_request(rq))) {
@@ -98,13 +89,10 @@ static int mtd_blktrans_thread(void *arg)
continue;
}

- dev = req->rq_disk->private_data;
- tr = dev->tr;
-
spin_unlock_irq(rq->queue_lock);

mutex_lock(&dev->lock);
- res = do_blktrans_request(tr, dev, req);
+ res = do_blktrans_request(dev->tr, dev, req);
mutex_unlock(&dev->lock);

spin_lock_irq(rq->queue_lock);
@@ -123,8 +111,8 @@ static int mtd_blktrans_thread(void *arg)

static void mtd_blktrans_request(struct request_queue *rq)
{
- struct mtd_blktrans_ops *tr = rq->queuedata;
- wake_up_process(tr->blkcore_priv->thread);
+ struct mtd_blktrans_dev *dev = rq->queuedata;
+ wake_up_process(dev->thread);
}

@@ -214,6 +202,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
struct mtd_blktrans_dev *d;
int last_devnum = -1;
struct gendisk *gd;
+ int ret;

if (mutex_trylock(&mtd_table_mutex)) {
mutex_unlock(&mtd_table_mutex);
@@ -239,6 +228,8 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
}
last_devnum = d->devnum;
}
+
+ ret = -EBUSY;
if (new->devnum == -1)
new->devnum = last_devnum+1;

@@ -247,7 +238,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
* with this number. */
if (new->devnum > (MINORMASK >> tr->part_bits) ||
(tr->part_bits && new->devnum >= 27 * 26))
- return -EBUSY;
+ goto error1;

list_add_tail(&new->list, &tr->devs);
added:
@@ -255,11 +246,16 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
if (!tr->writesect)
new->readonly = 1;

+
+ /* Create gendisk */
+ ret = -ENOMEM;
gd = alloc_disk(1 << tr->part_bits);
- if (!gd) {
- list_del(&new->list);
- return -ENOMEM;
- }
+
+ if (!gd)
+ goto error2;
+
+ new->disk = gd;
+ gd->private_data = new;
gd->major = tr->major;
gd->first_minor = (new->devnum) << tr->part_bits;
gd->fops = &mtd_blktrans_ops;
@@ -277,21 +273,49 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
snprintf(gd->disk_name, sizeof(gd->disk_name),
"%s%d", tr->name, new->devnum);

- /* 2.5 has capacity in units of 512 bytes while still
- having BLOCK_SIZE_BITS set to 10. Just to keep us amused. */
set_capacity(gd, (new->size * tr->blksize) >> 9);

- gd->private_data = new;
- new->blkcore_priv = gd;
- gd->queue = tr->blkcore_priv->rq;
+
+ /* Create the request queue */
+ spin_lock_init(&new->queue_lock);
+ new->rq = blk_init_queue(mtd_blktrans_request, &new->queue_lock);
+
+ if (!new->rq)
+ goto error3;
+
+ new->rq->queuedata = new;
+ blk_queue_logical_block_size(new->rq, tr->blksize);
+
+ if (tr->discard)
+ queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
+ new->rq);
+
+ gd->queue = new->rq;
+
+ /* Create processing thread */
+ /* TODO: workqueue ? */
+ new->thread = kthread_run(mtd_blktrans_thread, new,
+ "%s%d", tr->name, new->mtd->index);
+ if (IS_ERR(new->thread)) {
+ ret = PTR_ERR(new->thread);
+ goto error4;
+ }
gd->driverfs_dev = &new->mtd->dev;

if (new->readonly)
set_disk_ro(gd, 1);

add_disk(gd);
-
return 0;
+error4:
+ blk_cleanup_queue(new->rq);
+error3:
+ put_disk(new->disk);
+error2:
+ list_del(&new->list);
+error1:
+ kfree(new);
+ return ret;
}

int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)
@@ -303,9 +327,13 @@ int del_mtd_blktrans_dev(struct mtd_blktrans_dev *old)

list_del(&old->list);

- del_gendisk(old->blkcore_priv);
- put_disk(old->blkcore_priv);
+ /* stop new requests to arrive */
+ del_gendisk(old->disk);

+ /* Stop the thread */
+ kthread_stop(old->thread);
+
+ blk_cleanup_queue(old->rq);
return 0;
}

@@ -347,9 +375,6 @@ int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
if (!blktrans_notifier.list.next)
register_mtd_user(&blktrans_notifier);

- tr->blkcore_priv = kzalloc(sizeof(*tr->blkcore_priv), GFP_KERNEL);
- if (!tr->blkcore_priv)
- return -ENOMEM;

mutex_lock(&mtd_table_mutex);

@@ -357,39 +382,12 @@ int register_mtd_blktrans(struct mtd_blktrans_ops *tr)
if (ret) {
printk(KERN_WARNING "Unable to register %s block device on major %d: %d\n",
tr->name, tr->major, ret);
- kfree(tr->blkcore_priv);
mutex_unlock(&mtd_table_mutex);
return ret;
}
- spin_lock_init(&tr->blkcore_priv->queue_lock);
-
- tr->blkcore_priv->rq = blk_init_queue(mtd_blktrans_request, &tr->blkcore_priv->queue_lock);
- if (!tr->blkcore_priv->rq) {
- unregister_blkdev(tr->major, tr->name);
- kfree(tr->blkcore_priv);
- mutex_unlock(&mtd_table_mutex);
- return -ENOMEM;
- }
-
- tr->blkcore_priv->rq->queuedata = tr;
- blk_queue_logical_block_size(tr->blkcore_priv->rq, tr->blksize);
- if (tr->discard)
- queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
- tr->blkcore_priv->rq);

tr->blkshift = ffs(tr->blksize) - 1;

- tr->blkcore_priv->thread = kthread_run(mtd_blktrans_thread, tr,
- "%sd", tr->name);
- if (IS_ERR(tr->blkcore_priv->thread)) {
- ret = PTR_ERR(tr->blkcore_priv->thread);
- blk_cleanup_queue(tr->blkcore_priv->rq);
- unregister_blkdev(tr->major, tr->name);
- kfree(tr->blkcore_priv);
- mutex_unlock(&mtd_table_mutex);
- return ret;
- }
-
INIT_LIST_HEAD(&tr->devs);
list_add(&tr->list, &blktrans_majors);

@@ -408,8 +406,6 @@ int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)

mutex_lock(&mtd_table_mutex);

- /* Clean up the kernel thread */
- kthread_stop(tr->blkcore_priv->thread);

/* Remove it from the list of active majors */
list_del(&tr->list);
@@ -417,13 +413,9 @@ int deregister_mtd_blktrans(struct mtd_blktrans_ops *tr)
list_for_each_entry_safe(dev, next, &tr->devs, list)
tr->remove_dev(dev);

- blk_cleanup_queue(tr->blkcore_priv->rq);
unregister_blkdev(tr->major, tr->name);
-
mutex_unlock(&mtd_table_mutex);

- kfree(tr->blkcore_priv);
-
BUG_ON(!list_empty(&tr->devs));
return 0;
}
diff --git a/include/linux/mtd/blktrans.h b/include/linux/mtd/blktrans.h
index 8b4aa05..a4b3928 100644
--- a/include/linux/mtd/blktrans.h
+++ b/include/linux/mtd/blktrans.h
@@ -24,11 +24,13 @@ struct mtd_blktrans_dev {
int devnum;
unsigned long size;
int readonly;
- void *blkcore_priv; /* gendisk in 2.5, devfs_handle in 2.4 */
+ struct gendisk *disk;
+ struct task_struct *thread;
+ struct request_queue *rq;
+ spinlock_t queue_lock;
+ void *priv;
};

-struct blkcore_priv; /* Differs for 2.4 and 2.5 kernels; private */
-
struct mtd_blktrans_ops {
char *name;
int major;
@@ -60,8 +62,6 @@ struct mtd_blktrans_ops {
struct list_head devs;
struct list_head list;
struct module *owner;
-
- struct mtd_blkcore_priv *blkcore_priv;
};

extern int register_mtd_blktrans(struct mtd_blktrans_ops *tr);
--
1.6.3.3