Staging: zram: Remove need for explicit device initialization

Currently, the user has to explicitly write a positive value to
initstate sysfs node before the device can be used. This event
triggers allocation of per-device metadata like memory pool,
table array and so on.

We do not pre-initialize all zram devices since the 'table' array,
mapping disk blocks to compressed chunks, takes considerable amount
of memory (8 bytes per page). So, pre-initializing all devices will
be quite wasteful if only few or none of the devices are actually
used.

This explicit device initialization from user is an odd requirement and
can be easily avoided. We now initialize the device when first write is
done to the device.

Signed-off-by: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index 2ef93cc..a481551 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -108,6 +108,8 @@ struct zram {
 	struct request_queue *queue;
 	struct gendisk *disk;
 	int init_done;
+	/* Prevent concurrent execution of device init and reset */
+	struct mutex init_lock;
 	/*
 	 * This is the limit on amount of *uncompressed* worth of data
 	 * we can store in a disk.