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    Subject[PATCH 02/14] blktrans: remove mtd_blkcore_priv and switch to per device queue and thread
    Date
    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 | 126 ++++++++++++++++++++----------------------
    include/linux/mtd/blktrans.h | 10 ++--
    2 files changed, 64 insertions(+), 72 deletions(-)

    diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
    index c82e09b..bbdb26d 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);
    @@ -239,12 +228,13 @@ 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;

    - if ((new->devnum << tr->part_bits) > 256) {
    - return -EBUSY;
    - }
    + if ((new->devnum << tr->part_bits) > 256)
    + goto error1;

    list_add_tail(&new->list, &tr->devs);
    added:
    @@ -252,11 +242,16 @@ 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;
    @@ -274,13 +269,33 @@ 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)
    @@ -289,6 +304,15 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
    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)
    @@ -300,9 +324,13 @@ 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;
    }

    @@ -343,9 +371,6 @@ 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);

    @@ -353,39 +378,12 @@ 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);

    @@ -405,8 +403,6 @@ 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);
    @@ -414,13 +410,9 @@ 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


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