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Commit a644343c authored by Minchan Kim's avatar Minchan Kim Committed by Michael Benedict
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UPSTREAM: zram: add interface to specif backing device 

For writeback feature, user should set up backing device before the zram
working.

This patch enables the interface via /sys/block/zramX/backing_dev.

Currently, it supports block device only but it could be enhanced for
file as well.

Link: http://lkml.kernel.org/r/1498459987-24562-5-git-send-email-minchan@kernel.org


Signed-off-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Juneho Choi <juno.choi@lge.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>

(cherry picked from commit 013bf95a83ec760a2afc37fabd6bf13a9cdae205)
Signed-off-by: default avatarPeter Kalauskas <peskal@google.com>
Bug: 112488418
Change-Id: I4bbf12ed7496d476bddd574e756bac5c8a838089
parent ab46674a

drivers/block/zram/zram_drv.c

+142 −0
Original line number Diff line number Diff line
@@ -269,6 +269,141 @@ static ssize_t mem_used_max_store(struct device *dev, 
	return len;

}



#ifdef CONFIG_ZRAM_WRITEBACK

static bool zram_wb_enabled(struct zram *zram)

{

	return zram->backing_dev;

}



static void reset_bdev(struct zram *zram)

{

	struct block_device *bdev;



	if (!zram_wb_enabled(zram))

		return;



	bdev = zram->bdev;

	if (zram->old_block_size)

		set_blocksize(bdev, zram->old_block_size);

	blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);

	/* hope filp_close flush all of IO */

	filp_close(zram->backing_dev, NULL);

	zram->backing_dev = NULL;

	zram->old_block_size = 0;

	zram->bdev = NULL;

}



static ssize_t backing_dev_show(struct device *dev,

		struct device_attribute *attr, char *buf)

{

	struct zram *zram = dev_to_zram(dev);

	struct file *file = zram->backing_dev;

	char *p;

	ssize_t ret;



	down_read(&zram->init_lock);

	if (!zram_wb_enabled(zram)) {

		memcpy(buf, "none\n", 5);

		up_read(&zram->init_lock);

		return 5;

	}



	p = file_path(file, buf, PAGE_SIZE - 1);

	if (IS_ERR(p)) {

		ret = PTR_ERR(p);

		goto out;

	}



	ret = strlen(p);

	memmove(buf, p, ret);

	buf[ret++] = '\n';

out:

	up_read(&zram->init_lock);

	return ret;

}



static ssize_t backing_dev_store(struct device *dev,

		struct device_attribute *attr, const char *buf, size_t len)

{

	char *file_name;

	struct file *backing_dev = NULL;

	struct inode *inode;

	struct address_space *mapping;

	unsigned int old_block_size = 0;

	struct block_device *bdev = NULL;

	int err;

	struct zram *zram = dev_to_zram(dev);



	file_name = kmalloc(PATH_MAX, GFP_KERNEL);

	if (!file_name)

		return -ENOMEM;



	down_write(&zram->init_lock);

	if (init_done(zram)) {

		pr_info("Can't setup backing device for initialized device\n");

		err = -EBUSY;

		goto out;

	}



	strlcpy(file_name, buf, len);



	backing_dev = filp_open(file_name, O_RDWR|O_LARGEFILE, 0);

	if (IS_ERR(backing_dev)) {

		err = PTR_ERR(backing_dev);

		backing_dev = NULL;

		goto out;

	}



	mapping = backing_dev->f_mapping;

	inode = mapping->host;



	/* Support only block device in this moment */

	if (!S_ISBLK(inode->i_mode)) {

		err = -ENOTBLK;

		goto out;

	}



	bdev = bdgrab(I_BDEV(inode));

	err = blkdev_get(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL, zram);

	if (err < 0)

		goto out;



	old_block_size = block_size(bdev);

	err = set_blocksize(bdev, PAGE_SIZE);

	if (err)

		goto out;



	reset_bdev(zram);



	zram->old_block_size = old_block_size;

	zram->bdev = bdev;

	zram->backing_dev = backing_dev;

	up_write(&zram->init_lock);



	pr_info("setup backing device %s\n", file_name);

	kfree(file_name);



	return len;

out:

	if (bdev)

		blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);



	if (backing_dev)

		filp_close(backing_dev, NULL);



	up_write(&zram->init_lock);



	kfree(file_name);



	return err;

}



#else

static bool zram_wb_enabled(struct zram *zram) { return false; }

static inline void reset_bdev(struct zram *zram) {};

#endif





/*

 * We switched to per-cpu streams and this attr is not needed anymore.

 * However, we will keep it around for some time, because:
@@ -947,6 +1082,7 @@ static void zram_reset_device(struct zram *zram) 
	zram_meta_free(zram, disksize);

	memset(&zram->stats, 0, sizeof(zram->stats));

	zcomp_destroy(comp);

	reset_bdev(zram);

}



static ssize_t disksize_store(struct device *dev,
@@ -1072,6 +1208,9 @@ static DEVICE_ATTR_WO(mem_limit); 
static DEVICE_ATTR_WO(mem_used_max);

static DEVICE_ATTR_RW(max_comp_streams);

static DEVICE_ATTR_RW(comp_algorithm);

#ifdef CONFIG_ZRAM_WRITEBACK

static DEVICE_ATTR_RW(backing_dev);

#endif



static struct attribute *zram_disk_attrs[] = {

	&dev_attr_disksize.attr,
@@ -1082,6 +1221,9 @@ static struct attribute *zram_disk_attrs[] = { 
	&dev_attr_mem_used_max.attr,

	&dev_attr_max_comp_streams.attr,

	&dev_attr_comp_algorithm.attr,

#ifdef CONFIG_ZRAM_WRITEBACK

	&dev_attr_backing_dev.attr,

#endif

	&dev_attr_io_stat.attr,

	&dev_attr_mm_stat.attr,

	&dev_attr_debug_stat.attr,

drivers/block/zram/zram_drv.h

+5 −0
Original line number Diff line number Diff line
@@ -115,5 +115,10 @@ struct zram { 
	 * zram is claimed so open request will be failed

	 */

	bool claim; /* Protected by bdev->bd_mutex */

#ifdef CONFIG_ZRAM_WRITEBACK

	struct file *backing_dev;

	struct block_device *bdev;

	unsigned int old_block_size;

#endif

};

#endif