1 files changed, 77 insertions, 18 deletions

diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index e77fb6ea40c9..91d94b564433 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -169,7 +169,7 @@ static inline int is_partial_io(struct bio_vec *bvec)
 static inline int valid_io_request(struct zram *zram, struct bio *bio)
 {
 	u64 start, end, bound;
-	
+
 	/* unaligned request */
 	if (unlikely(bio->bi_sector & (ZRAM_SECTOR_PER_LOGICAL_BLOCK - 1)))
 		return 0;
@@ -418,14 +418,6 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 			goto out;
 	}
 
-	/*
-	 * System overwrites unused sectors. Free memory associated
-	 * with this sector now.
-	 */
-	if (meta->table[index].handle ||
-	    zram_test_flag(meta, index, ZRAM_ZERO))
-		zram_free_page(zram, index);
-
 	user_mem = kmap_atomic(page);
 
 	if (is_partial_io(bvec)) {
@@ -439,12 +431,23 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 
 	if (page_zero_filled(uncmem)) {
 		kunmap_atomic(user_mem);
+		/* Free memory associated with this sector now. */
+		zram_free_page(zram, index);
+
 		zram->stats.pages_zero++;
 		zram_set_flag(meta, index, ZRAM_ZERO);
 		ret = 0;
 		goto out;
 	}
 
+	/*
+	 * zram_slot_free_notify could miss free so that let's
+	 * double check.
+	 */
+	if (unlikely(meta->table[index].handle ||
+			zram_test_flag(meta, index, ZRAM_ZERO)))
+		zram_free_page(zram, index);
+
 	ret = lzo1x_1_compress(uncmem, PAGE_SIZE, src, &clen,
 			       meta->compress_workmem);
 
@@ -486,6 +489,12 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 
 	zs_unmap_object(meta->mem_pool, handle);
 
+	/*
+	 * Free memory associated with this sector
+	 * before overwriting unused sectors.
+	 */
+	zram_free_page(zram, index);
+
 	meta->table[index].handle = handle;
 	meta->table[index].size = clen;
 
@@ -504,6 +513,20 @@ 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)
 {
@@ -511,10 +534,12 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 
 	if (rw == READ) {
 		down_read(&zram->lock);
+		handle_pending_slot_free(zram);
 		ret = zram_bvec_read(zram, bvec, index, offset, bio);
 		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);
 	}
@@ -522,11 +547,13 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 	return ret;
 }
 
-static void zram_reset_device(struct zram *zram)
+static void zram_reset_device(struct zram *zram, bool reset_capacity)
 {
 	size_t index;
 	struct zram_meta *meta;
 
+	flush_work(&zram->free_work);
+
 	down_write(&zram->init_lock);
 	if (!zram->init_done) {
 		up_write(&zram->init_lock);
@@ -551,7 +578,8 @@ static void zram_reset_device(struct zram *zram)
 	memset(&zram->stats, 0, sizeof(zram->stats));
 
 	zram->disksize = 0;
-	set_capacity(zram->disk, 0);
+	if (reset_capacity)
+		set_capacity(zram->disk, 0);
 	up_write(&zram->init_lock);
 }
 
@@ -635,7 +663,7 @@ static ssize_t reset_store(struct device *dev,
 	if (bdev)
 		fsync_bdev(bdev);
 
-	zram_reset_device(zram);
+	zram_reset_device(zram, true);
 	return len;
 }
 
@@ -720,16 +748,40 @@ 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;
 
 	zram = bdev->bd_disk->private_data;
-	down_write(&zram->lock);
-	zram_free_page(zram, index);
-	up_write(&zram->lock);
 	atomic64_inc(&zram->stats.notify_free);
+
+	free_rq = kmalloc(sizeof(struct zram_slot_free), GFP_ATOMIC);
+	if (!free_rq)
+		return;
+
+	free_rq->index = index;
+	add_slot_free(zram, free_rq);
+	schedule_work(&zram->free_work);
 }
 
 static const struct block_device_operations zram_devops = {
@@ -776,6 +828,10 @@ 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",
@@ -902,10 +958,12 @@ static void __exit zram_exit(void)
 	for (i = 0; i < num_devices; i++) {
 		zram = &zram_devices[i];
 
-		get_disk(zram->disk);
 		destroy_device(zram);
-		zram_reset_device(zram);
-		put_disk(zram->disk);
+		/*
+		 * Shouldn't access zram->disk after destroy_device
+		 * because destroy_device already released zram->disk.
+		 */
+		zram_reset_device(zram, false);
 	}
 
 	unregister_blkdev(zram_major, "zram");
@@ -923,3 +981,4 @@ MODULE_PARM_DESC(num_devices, "Number of zram devices");
 MODULE_LICENSE("Dual BSD/GPL");
 MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
 MODULE_DESCRIPTION("Compressed RAM Block Device");
+MODULE_ALIAS("devname:zram");