Hello Sergey,
On Thu, Jan 09, 2014 at 03:57:46PM +0300, Sergey Senozhatsky wrote:
> Introduce init_done() helper function which allows us to drop
> `init_done' struct zram member. init_done() uses the fact that
> ->init_done == 1 equals to ->meta != NULL.
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com>
It would be good without any harm but I'm just considering to
change the lock with rcu with atomic variable.
Please give me a time and feedback to you in next week.
Thanks.
>
> ---
>
> drivers/block/zram/zram_drv.c | 21 +++++++++++----------
> drivers/block/zram/zram_drv.h | 12 +++++-------
> 2 files changed, 16 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 108f273..833d24f 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -42,6 +42,11 @@ static struct zram *zram_devices;
> /* Module params (documentation at end) */
> static unsigned int num_devices = 1;
>
> +static inline int init_done(struct zram *zram)
> +{
> + return zram->meta != NULL;
> +}
> +
> static inline struct zram *dev_to_zram(struct device *dev)
> {
> return (struct zram *)dev_to_disk(dev)->private_data;
> @@ -60,7 +65,7 @@ static ssize_t initstate_show(struct device *dev,
> {
> struct zram *zram = dev_to_zram(dev);
>
> - return sprintf(buf, "%u\n", zram->init_done);
> + return sprintf(buf, "%u\n", init_done(zram));
> }
>
> static ssize_t num_reads_show(struct device *dev,
> @@ -133,7 +138,7 @@ static ssize_t mem_used_total_show(struct device *dev,
> struct zram_meta *meta = zram->meta;
>
> down_read(&zram->init_lock);
> - if (zram->init_done)
> + if (init_done(zram))
> val = zs_get_total_size_bytes(meta->mem_pool);
> up_read(&zram->init_lock);
>
> @@ -556,14 +561,12 @@ static void zram_reset_device(struct zram *zram, bool
> reset_capacity)
> flush_work(&zram->free_work);
>
> down_write(&zram->init_lock);
> - if (!zram->init_done) {
> + if (!init_done(zram)) {
> up_write(&zram->init_lock);
> return;
> }
>
> meta = zram->meta;
> - zram->init_done = 0;
> -
> /* Free all pages that are still in this zram device */
> for (index = 0; index < zram->disksize >> PAGE_SHIFT; index++) {
> unsigned long handle = meta->table[index].handle;
> @@ -604,8 +607,6 @@ static void zram_init_device(struct zram *zram, struct
> zram_meta *meta)
> queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
>
> zram->meta = meta;
> - zram->init_done = 1;
> -
> pr_debug("Initialization done!\n");
> }
>
> @@ -623,7 +624,7 @@ static ssize_t disksize_store(struct device *dev,
> disksize = PAGE_ALIGN(disksize);
> meta = zram_meta_alloc(disksize);
> down_write(&zram->init_lock);
> - if (zram->init_done) {
> + if (init_done(zram)) {
> up_write(&zram->init_lock);
> zram_meta_free(meta);
> pr_info("Cannot change disksize for initialized device\n");
> @@ -744,7 +745,7 @@ static void zram_make_request(struct request_queue
> *queue, struct bio *bio)
> struct zram *zram = queue->queuedata;
>
> down_read(&zram->init_lock);
> - if (unlikely(!zram->init_done))
> + if (unlikely(!init_done(zram)))
> goto error;
>
> if (!valid_io_request(zram, bio)) {
> @@ -893,7 +894,7 @@ static int create_device(struct zram *zram, int device_id)
> goto out_free_disk;
> }
>
> - zram->init_done = 0;
> + zram->meta = NULL;
> return 0;
>
> out_free_disk:
> diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> index d8f6596..1388bad 100644
> --- a/drivers/block/zram/zram_drv.h
> +++ b/drivers/block/zram/zram_drv.h
> @@ -99,26 +99,24 @@ struct zram_slot_free {
> };
>
> struct zram {
> + /* Prevent concurrent execution of device init, reset and R/W request */
> + struct rw_semaphore init_lock;
> struct zram_meta *meta;
> +
> struct rw_semaphore lock; /* protect compression buffers, table,
> * 32bit stat counters against concurrent
> * notifications, reads and writes */
> -
> - struct work_struct free_work; /* handle pending free request */
> struct zram_slot_free *slot_free_rq; /* list head of free request */
> + spinlock_t slot_free_lock;
> + struct work_struct free_work; /* handle pending free request */
>
> struct request_queue *queue;
> struct gendisk *disk;
> - int init_done;
> - /* Prevent concurrent execution of device init, reset and R/W request */
> - struct rw_semaphore init_lock;
> /*
> * This is the limit on amount of *uncompressed* worth of data
> * we can store in a disk.
> */
> u64 disksize; /* bytes */
> - spinlock_t slot_free_lock;
> -
> struct zram_stats stats;
> };
> #endif
> --
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--
Kind regards,
Minchan Kim
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