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Commit 0e05f38f authored by Minchan Kim's avatar Minchan Kim Committed by Peter Kalauskas
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BACKPORT: zram: add free space management in backing device 

With backing device, zram needs management of free space of backing
device.

This patch adds bitmap logic to manage free space which is very naive.
However, it would be simple enough as considering uncompressible pages's
frequenty in zram.

Link: http://lkml.kernel.org/r/1498459987-24562-6-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 1363d4662a0d28dfdb81ef426c88c9a8dbf7c338)
Signed-off-by: default avatarPeter Kalauskas <peskal@google.com>
Bug: 112488418
Change-Id: Ibfa13bb22a93a10150cd45d7ee6f34d4330922e9
parent 9ac886a3

drivers/block/zram/zram_drv.c

+55 −1
Original line number Diff line number Diff line
@@ -291,6 +291,9 @@ static void reset_bdev(struct zram *zram) 
	zram->backing_dev = NULL;

	zram->old_block_size = 0;

	zram->bdev = NULL;



	kvfree(zram->bitmap);

	zram->bitmap = NULL;

}



static ssize_t backing_dev_show(struct device *dev,
@@ -329,10 +332,12 @@ static ssize_t backing_dev_store(struct device *dev, 
	struct file *backing_dev = NULL;

	struct inode *inode;

	struct address_space *mapping;

	unsigned int old_block_size = 0;

	unsigned int bitmap_sz, old_block_size = 0;

	unsigned long nr_pages, *bitmap = NULL;

	struct block_device *bdev = NULL;

	int err;

	struct zram *zram = dev_to_zram(dev);

	gfp_t kmalloc_flags;



	file_name = kmalloc(PATH_MAX, GFP_KERNEL);

	if (!file_name)
@@ -368,16 +373,34 @@ static ssize_t backing_dev_store(struct device *dev, 
	if (err < 0)

		goto out;



	nr_pages = i_size_read(inode) >> PAGE_SHIFT;

	bitmap_sz = BITS_TO_LONGS(nr_pages) * sizeof(long);

	kmalloc_flags = GFP_KERNEL | __GFP_ZERO;

	if (bitmap_sz > PAGE_SIZE)

		kmalloc_flags |= __GFP_NOWARN | __GFP_NORETRY;



	bitmap = kmalloc_node(bitmap_sz, kmalloc_flags, NUMA_NO_NODE);

	if (!bitmap && bitmap_sz > PAGE_SIZE)

		bitmap = vzalloc(bitmap_sz);



	if (!bitmap) {

		err = -ENOMEM;

		goto out;

	}



	old_block_size = block_size(bdev);

	err = set_blocksize(bdev, PAGE_SIZE);

	if (err)

		goto out;



	reset_bdev(zram);

	spin_lock_init(&zram->bitmap_lock);



	zram->old_block_size = old_block_size;

	zram->bdev = bdev;

	zram->backing_dev = backing_dev;

	zram->bitmap = bitmap;

	zram->nr_pages = nr_pages;

	up_write(&zram->init_lock);



	pr_info("setup backing device %s\n", file_name);
@@ -385,6 +408,9 @@ static ssize_t backing_dev_store(struct device *dev, 


	return len;

out:

	if (bitmap)

		kvfree(bitmap);



	if (bdev)

		blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
@@ -398,6 +424,34 @@ static ssize_t backing_dev_store(struct device *dev, 
	return err;

}



static unsigned long get_entry_bdev(struct zram *zram)

{

	unsigned long entry;



	spin_lock(&zram->bitmap_lock);

	/* skip 0 bit to confuse zram.handle = 0 */

	entry = find_next_zero_bit(zram->bitmap, zram->nr_pages, 1);

	if (entry == zram->nr_pages) {

		spin_unlock(&zram->bitmap_lock);

		return 0;

	}



	set_bit(entry, zram->bitmap);

	spin_unlock(&zram->bitmap_lock);



	return entry;

}



static void put_entry_bdev(struct zram *zram, unsigned long entry)

{

	int was_set;



	spin_lock(&zram->bitmap_lock);

	was_set = test_and_clear_bit(entry, zram->bitmap);

	spin_unlock(&zram->bitmap_lock);

	WARN_ON_ONCE(!was_set);

}



#else

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

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

drivers/block/zram/zram_drv.h

+3 −0
Original line number Diff line number Diff line
@@ -119,6 +119,9 @@ struct zram { 
	struct file *backing_dev;

	struct block_device *bdev;

	unsigned int old_block_size;

	unsigned long *bitmap;

	unsigned long nr_pages;

	spinlock_t bitmap_lock;

#endif

};

#endif