zram: remove workqueue for freeing removed pending slot

Commit a0c516cbfc74 ("zram: don't grab mutex in zram_slot_free_noity")
introduced free request pending code to avoid scheduling by mutex under
spinlock and it was a mess which made code lenghty and increased
overhead.

Now, we don't need zram->lock any more to free slot so this patch
reverts it and then, tb_lock should protect it.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 6 insertions, 58 deletions

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 24e6426cf258..f1a3c958d84b 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -522,20 +522,6 @@ out:
         return ret;
 }
 
-static void handle_pending_slot_free(struct zram *zram)
-{
-        struct zram_slot_free *free_rq;
-
-        spin_lock(&zram->slot_free_lock);
-        while (zram->slot_free_rq) {
-                free_rq = zram->slot_free_rq;
-                zram->slot_free_rq = free_rq->next;
-                zram_free_page(zram, free_rq->index);
-                kfree(free_rq);
-        }
-        spin_unlock(&zram->slot_free_lock);
-}
-
 static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
                         int offset, struct bio *bio, int rw)
 {
@@ -547,7 +533,6 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
                 up_read(&zram->lock);
         } else {
                 down_write(&zram->lock);
-                handle_pending_slot_free(zram);
                 ret = zram_bvec_write(zram, bvec, index, offset);
                 up_write(&zram->lock);
         }
@@ -566,8 +551,6 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
                 return;
         }
 
-        flush_work(&zram->free_work);
-
         meta = zram->meta;
         zram->init_done = 0;
 
@@ -769,40 +752,19 @@ error:
         bio_io_error(bio);
 }
 
-static void zram_slot_free(struct work_struct *work)
-{
-        struct zram *zram;
-
-        zram = container_of(work, struct zram, free_work);
-        down_write(&zram->lock);
-        handle_pending_slot_free(zram);
-        up_write(&zram->lock);
-}
-
-static void add_slot_free(struct zram *zram, struct zram_slot_free *free_rq)
-{
-        spin_lock(&zram->slot_free_lock);
-        free_rq->next = zram->slot_free_rq;
-        zram->slot_free_rq = free_rq;
-        spin_unlock(&zram->slot_free_lock);
-}
-
 static void zram_slot_free_notify(struct block_device *bdev,
                                 unsigned long index)
 {
         struct zram *zram;
-        struct zram_slot_free *free_rq;
+        struct zram_meta *meta;
 
         zram = bdev->bd_disk->private_data;
-        atomic64_inc(&zram->stats.notify_free);
-
-        free_rq = kmalloc(sizeof(struct zram_slot_free), GFP_ATOMIC);
-        if (!free_rq)
-                return;
+        meta = zram->meta;
 
-        free_rq->index = index;
-        add_slot_free(zram, free_rq);
-        schedule_work(&zram->free_work);
+        write_lock(&meta->tb_lock);
+        zram_free_page(zram, index);
+        write_unlock(&meta->tb_lock);
+        atomic64_inc(&zram->stats.notify_free);
 }
 
 static const struct block_device_operations zram_devops = {
@@ -849,10 +811,6 @@ static int create_device(struct zram *zram, int device_id)
         init_rwsem(&zram->lock);
         init_rwsem(&zram->init_lock);
 
-        INIT_WORK(&zram->free_work, zram_slot_free);
-        spin_lock_init(&zram->slot_free_lock);
-        zram->slot_free_rq = NULL;
-
         zram->queue = blk_alloc_queue(GFP_KERNEL);
         if (!zram->queue) {
                 pr_err("Error allocating disk queue for device %d\n",
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index c3f453f04974..d876300da6c9 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -90,20 +90,11 @@ struct zram_meta {
         struct zs_pool *mem_pool;
 };
 
-struct zram_slot_free {
-        unsigned long index;
-        struct zram_slot_free *next;
-};
-
 struct zram {
         struct zram_meta *meta;
         struct rw_semaphore lock; /* protect compression buffers,
                                    * reads and writes
                                    */
-
-        struct work_struct free_work;  /* handle pending free request */
-        struct zram_slot_free *slot_free_rq; /* list head of free request */
-
         struct request_queue *queue;
         struct gendisk *disk;
         int init_done;
@@ -114,7 +105,6 @@ struct zram {
          * we can store in a disk.
          */
         u64 disksize;   /* bytes */
-        spinlock_t slot_free_lock;
 
         struct zram_stats stats;
 };