From 1d69a3f8ae77e3dbfdc1356225cce5ea9c366aec Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Tue, 8 Jan 2019 15:22:53 -0800 Subject: zram: idle writeback fixes and cleanup This patch includes some fixes and cleanup for idle-page writeback. 1. writeback_limit interface Now writeback_limit interface is rather conusing. For example, once writeback limit budget is exausted, admin can see 0 from /sys/block/zramX/writeback_limit which is same semantic with disable writeback_limit at this moment. IOW, admin cannot tell that zero came from disable writeback limit or exausted writeback limit. To make the interface clear, let's sepatate enable of writeback limit to another knob - /sys/block/zram0/writeback_limit_enable * before: while true : # to re-enable writeback limit once previous one is used up echo 0 > /sys/block/zram0/writeback_limit echo $((200<<20)) > /sys/block/zram0/writeback_limit .. .. # used up the writeback limit budget * new # To enable writeback limit, from the beginning, admin should # enable it. echo $((200<<20)) > /sys/block/zram0/writeback_limit echo 1 > /sys/block/zram/0/writeback_limit_enable while true : echo $((200<<20)) > /sys/block/zram0/writeback_limit .. .. # used up the writeback limit budget It's much strightforward. 2. fix condition check idle/huge writeback mode check The mode in writeback_store is not bit opeartion any more so no need to use bit operations. Furthermore, current condition check is broken in that it does writeback every pages regardless of huge/idle. 3. clean up idle_store No need to use goto. [minchan@kernel.org: missed spin_lock_init] Link: http://lkml.kernel.org/r/20190103001601.GA255139@google.com Link: http://lkml.kernel.org/r/20181224033529.19450-1-minchan@kernel.org Signed-off-by: Minchan Kim Suggested-by: John Dias Cc: Sergey Senozhatsky Cc: John Dias Cc: Srinivas Paladugu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/block/zram/zram_drv.c | 90 +++++++++++++++++++++++++++++++------------ 1 file changed, 66 insertions(+), 24 deletions(-) (limited to 'drivers/block/zram/zram_drv.c') diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 33c5cc879f24..04ca65912638 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -316,11 +316,9 @@ static ssize_t idle_store(struct device *dev, * See the comment in writeback_store. */ zram_slot_lock(zram, index); - if (!zram_allocated(zram, index) || - zram_test_flag(zram, index, ZRAM_UNDER_WB)) - goto next; - zram_set_flag(zram, index, ZRAM_IDLE); -next: + if (zram_allocated(zram, index) && + !zram_test_flag(zram, index, ZRAM_UNDER_WB)) + zram_set_flag(zram, index, ZRAM_IDLE); zram_slot_unlock(zram, index); } @@ -330,6 +328,41 @@ next: } #ifdef CONFIG_ZRAM_WRITEBACK +static ssize_t writeback_limit_enable_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + struct zram *zram = dev_to_zram(dev); + u64 val; + ssize_t ret = -EINVAL; + + if (kstrtoull(buf, 10, &val)) + return ret; + + down_read(&zram->init_lock); + spin_lock(&zram->wb_limit_lock); + zram->wb_limit_enable = val; + spin_unlock(&zram->wb_limit_lock); + up_read(&zram->init_lock); + ret = len; + + return ret; +} + +static ssize_t writeback_limit_enable_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + bool val; + struct zram *zram = dev_to_zram(dev); + + down_read(&zram->init_lock); + spin_lock(&zram->wb_limit_lock); + val = zram->wb_limit_enable; + spin_unlock(&zram->wb_limit_lock); + up_read(&zram->init_lock); + + return scnprintf(buf, PAGE_SIZE, "%d\n", val); +} + static ssize_t writeback_limit_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { @@ -341,9 +374,9 @@ static ssize_t writeback_limit_store(struct device *dev, return ret; down_read(&zram->init_lock); - atomic64_set(&zram->stats.bd_wb_limit, val); - if (val == 0) - zram->stop_writeback = false; + spin_lock(&zram->wb_limit_lock); + zram->bd_wb_limit = val; + spin_unlock(&zram->wb_limit_lock); up_read(&zram->init_lock); ret = len; @@ -357,7 +390,9 @@ static ssize_t writeback_limit_show(struct device *dev, struct zram *zram = dev_to_zram(dev); down_read(&zram->init_lock); - val = atomic64_read(&zram->stats.bd_wb_limit); + spin_lock(&zram->wb_limit_lock); + val = zram->bd_wb_limit; + spin_unlock(&zram->wb_limit_lock); up_read(&zram->init_lock); return scnprintf(buf, PAGE_SIZE, "%llu\n", val); @@ -588,8 +623,8 @@ static int read_from_bdev_async(struct zram *zram, struct bio_vec *bvec, return 1; } -#define HUGE_WRITEBACK 0x1 -#define IDLE_WRITEBACK 0x2 +#define HUGE_WRITEBACK 1 +#define IDLE_WRITEBACK 2 static ssize_t writeback_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) @@ -602,7 +637,7 @@ static ssize_t writeback_store(struct device *dev, struct page *page; ssize_t ret, sz; char mode_buf[8]; - unsigned long mode = -1UL; + int mode = -1; unsigned long blk_idx = 0; sz = strscpy(mode_buf, buf, sizeof(mode_buf)); @@ -618,7 +653,7 @@ static ssize_t writeback_store(struct device *dev, else if (!strcmp(mode_buf, "huge")) mode = HUGE_WRITEBACK; - if (mode == -1UL) + if (mode == -1) return -EINVAL; down_read(&zram->init_lock); @@ -645,10 +680,13 @@ static ssize_t writeback_store(struct device *dev, bvec.bv_len = PAGE_SIZE; bvec.bv_offset = 0; - if (zram->stop_writeback) { + spin_lock(&zram->wb_limit_lock); + if (zram->wb_limit_enable && !zram->bd_wb_limit) { + spin_unlock(&zram->wb_limit_lock); ret = -EIO; break; } + spin_unlock(&zram->wb_limit_lock); if (!blk_idx) { blk_idx = alloc_block_bdev(zram); @@ -667,10 +705,11 @@ static ssize_t writeback_store(struct device *dev, zram_test_flag(zram, index, ZRAM_UNDER_WB)) goto next; - if ((mode & IDLE_WRITEBACK && - !zram_test_flag(zram, index, ZRAM_IDLE)) && - (mode & HUGE_WRITEBACK && - !zram_test_flag(zram, index, ZRAM_HUGE))) + if (mode == IDLE_WRITEBACK && + !zram_test_flag(zram, index, ZRAM_IDLE)) + goto next; + if (mode == HUGE_WRITEBACK && + !zram_test_flag(zram, index, ZRAM_HUGE)) goto next; /* * Clearing ZRAM_UNDER_WB is duty of caller. @@ -732,11 +771,10 @@ static ssize_t writeback_store(struct device *dev, zram_set_element(zram, index, blk_idx); blk_idx = 0; atomic64_inc(&zram->stats.pages_stored); - if (atomic64_add_unless(&zram->stats.bd_wb_limit, - -1 << (PAGE_SHIFT - 12), 0)) { - if (atomic64_read(&zram->stats.bd_wb_limit) == 0) - zram->stop_writeback = true; - } + spin_lock(&zram->wb_limit_lock); + if (zram->wb_limit_enable && zram->bd_wb_limit > 0) + zram->bd_wb_limit -= 1UL << (PAGE_SHIFT - 12); + spin_unlock(&zram->wb_limit_lock); next: zram_slot_unlock(zram, index); } @@ -1812,6 +1850,7 @@ static DEVICE_ATTR_RW(comp_algorithm); static DEVICE_ATTR_RW(backing_dev); static DEVICE_ATTR_WO(writeback); static DEVICE_ATTR_RW(writeback_limit); +static DEVICE_ATTR_RW(writeback_limit_enable); #endif static struct attribute *zram_disk_attrs[] = { @@ -1828,6 +1867,7 @@ static struct attribute *zram_disk_attrs[] = { &dev_attr_backing_dev.attr, &dev_attr_writeback.attr, &dev_attr_writeback_limit.attr, + &dev_attr_writeback_limit_enable.attr, #endif &dev_attr_io_stat.attr, &dev_attr_mm_stat.attr, @@ -1867,7 +1907,9 @@ static int zram_add(void) device_id = ret; init_rwsem(&zram->init_lock); - +#ifdef CONFIG_ZRAM_WRITEBACK + spin_lock_init(&zram->wb_limit_lock); +#endif queue = blk_alloc_queue(GFP_KERNEL); if (!queue) { pr_err("Error allocating disk queue for device %d\n", -- cgit v1.2.3-59-g8ed1b