zram: delete zram_init_device()

allocate new `zram_meta' in disksize_store() only for uninitialised zram
device, saving a number of allocations and deallocations in case if
disksize_store() was called on currently used device. at the same time
zram_meta stack variable is not necessary, because we can set ->meta
directly. there is also no need in setting QUEUE_FLAG_NONROT queue on
every disksize_store(), set it once during device creation.

[[e-mail]: handle zram->meta alloc fail case]
[[e-mail]: prevent lockdep spew of init_lock]
Signed-off-by: Sergey Senozhatsky <[e-mail]>
Signed-off-by: Minchan Kim <[e-mail]>
Acked-by: Jerome Marchand <[e-mail]>
Cc: Sasha Levin <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/block/zram/zram_drv.c

···
 	up_write(&zram->init_lock);
 }
 
-static void zram_init_device(struct zram *zram, struct zram_meta *meta)
-{
-	/* zram devices sort of resembles non-rotational disks */
-	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
-	zram->meta = meta;
-	pr_debug("Initialization done!\n");
-}
-
 static ssize_t disksize_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
···
 	meta = zram_meta_alloc(disksize);
 	if (!meta)
 		return -ENOMEM;
+
 	down_write(&zram->init_lock);
 	if (init_done(zram)) {
-		up_write(&zram->init_lock);
 		zram_meta_free(meta);
+		up_write(&zram->init_lock);
 		pr_info("Cannot change disksize for initialized device\n");
 		return -EBUSY;
 	}
 
+	zram->meta = meta;
 	zram->disksize = disksize;
 	set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
-	zram_init_device(zram, meta);
 	up_write(&zram->init_lock);
 
 	return len;
···
 
 	/* Actual capacity set using syfs (/sys/block/zram<id>/disksize */
 	set_capacity(zram->disk, 0);
-
+	/* zram devices sort of resembles non-rotational disks */
+	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, zram->disk->queue);
 	/*
 	 * To ensure that we always get PAGE_SIZE aligned
 	 * and n*PAGE_SIZED sized I/O requests.