From 1363d4662a0d28dfdb81ef426c88c9a8dbf7c338 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Wed, 6 Sep 2017 16:19:57 -0700 Subject: [PATCH] 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: Minchan Kim Cc: Juneho Choi Cc: Sergey Senozhatsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/zram/zram_drv.c | 48 ++++++++++++++++++++++++++++++++++- drivers/block/zram/zram_drv.h | 3 +++ 2 files changed, 50 insertions(+), 1 deletion(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 81eb81f17ef9..fcdbbb1e7745 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -292,6 +292,9 @@ 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, @@ -330,7 +333,8 @@ 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); @@ -369,16 +373,27 @@ 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); + bitmap = kvzalloc(bitmap_sz, GFP_KERNEL); + 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); @@ -386,6 +401,9 @@ 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); @@ -399,6 +417,34 @@ out: 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) {}; diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 113a41118918..707aec0a2681 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -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 -- 2.20.1