zram: deprecate zram attrs sysfs nodes (8f7d282c) · Commits · 戴 / test

Documentation/ABI/obsolete/sysfs-block-zram

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		What: /sys/block/zram<id>/num_reads
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The num_reads file is read-only and specifies the number of
		reads (failed or successful) done on this device.
		Now accessible via zram<id>/stat node.

		What: /sys/block/zram<id>/num_writes
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The num_writes file is read-only and specifies the number of
		writes (failed or successful) done on this device.
		Now accessible via zram<id>/stat node.

		What: /sys/block/zram<id>/invalid_io
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The invalid_io file is read-only and specifies the number of
		non-page-size-aligned I/O requests issued to this device.
		Now accessible via zram<id>/io_stat node.

		What: /sys/block/zram<id>/failed_reads
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The failed_reads file is read-only and specifies the number of
		failed reads happened on this device.
		Now accessible via zram<id>/io_stat node.

		What: /sys/block/zram<id>/failed_writes
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The failed_writes file is read-only and specifies the number of
		failed writes happened on this device.
		Now accessible via zram<id>/io_stat node.

		What: /sys/block/zram<id>/notify_free
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The notify_free file is read-only. Depending on device usage
		scenario it may account a) the number of pages freed because
		of swap slot free notifications or b) the number of pages freed
		because of REQ_DISCARD requests sent by bio. The former ones
		are sent to a swap block device when a swap slot is freed, which
		implies that this disk is being used as a swap disk. The latter
		ones are sent by filesystem mounted with discard option,
		whenever some data blocks are getting discarded.
		Now accessible via zram<id>/io_stat node.

		What: /sys/block/zram<id>/zero_pages
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The zero_pages file is read-only and specifies number of zero
		filled pages written to this disk. No memory is allocated for
		such pages.
		Now accessible via zram<id>/mm_stat node.

		What: /sys/block/zram<id>/orig_data_size
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The orig_data_size file is read-only and specifies uncompressed
		size of data stored in this disk. This excludes zero-filled
		pages (zero_pages) since no memory is allocated for them.
		Unit: bytes
		Now accessible via zram<id>/mm_stat node.

		What: /sys/block/zram<id>/compr_data_size
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The compr_data_size file is read-only and specifies compressed
		size of data stored in this disk. So, compression ratio can be
		calculated using orig_data_size and this statistic.
		Unit: bytes
		Now accessible via zram<id>/mm_stat node.

		What: /sys/block/zram<id>/mem_used_total
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The mem_used_total file is read-only and specifies the amount
		of memory, including allocator fragmentation and metadata
		overhead, allocated for this disk. So, allocator space
		efficiency can be calculated using compr_data_size and this
		statistic.
		Unit: bytes
		Now accessible via zram<id>/mm_stat node.

		What: /sys/block/zram<id>/mem_used_max
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The mem_used_max file is read/write and specifies the amount
		of maximum memory zram have consumed to store compressed data.
		For resetting the value, you should write "0". Otherwise,
		you could see -EINVAL.
		Unit: bytes
		Downgraded to write-only node: so it's possible to set new
		value only; its current value is stored in zram<id>/mm_stat
		node.

		What: /sys/block/zram<id>/mem_limit
		Date: August 2015
		Contact: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
		Description:
		The mem_limit file is read/write and specifies the maximum
		amount of memory ZRAM can use to store the compressed data.
		The limit could be changed in run time and "0" means disable
		the limit. No limit is the initial state. Unit: bytes
		Downgraded to write-only node: so it's possible to set new
		value only; its current value is stored in zram<id>/mm_stat
		node.

Documentation/blockdev/zram.txt

+16 −0

Original line number	Diff line number	Diff line
		@@ -128,6 +128,22 @@ mem_limit RW the maximum amount of memory ZRAM can use to store
		num_migrated RO the number of objects migrated migrated by compaction


		WARNING
		=======
		per-stat sysfs attributes are considered to be deprecated.
		The basic strategy is:
		-- the existing RW nodes will be downgraded to WO nodes (in linux 4.11)
		-- deprecated RO sysfs nodes will eventually be removed (in linux 4.11)

		The list of deprecated attributes can be found here:
		Documentation/ABI/obsolete/sysfs-block-zram

		Basically, every attribute that has its own read accessible sysfs node
		(e.g. num_reads) AND is accessible via one of the stat files (zram<id>/stat
		or zram<id>/io_stat or zram<id>/mm_stat) is considered to be deprecated.

		User space is advised to use the following files to read the device statistics.

		File /sys/block/zram<id>/stat

		Represents block layer statistics. Read Documentation/block/stat.txt for

drivers/block/zram/zram_drv.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -43,11 +43,22 @@ static const char *default_compressor = "lzo";
		/* Module params (documentation at end) */
		static unsigned int num_devices = 1;

		static inline void deprecated_attr_warn(const char *name)
		{
		pr_warn_once("%d (%s) Attribute %s (and others) will be removed. %s\n",
		task_pid_nr(current),
		current->comm,
		name,
		"See zram documentation.");
		}

		#define ZRAM_ATTR_RO(name) \
		static ssize_t name##_show(struct device *d, \
		struct device_attribute attr, char b) \
		{ \
		struct zram *zram = dev_to_zram(d); \
		\
		deprecated_attr_warn(__stringify(name)); \
		return scnprintf(b, PAGE_SIZE, "%llu\n", \
		(u64)atomic64_read(&zram->stats.name)); \
		} \
		@@ -89,6 +100,7 @@ static ssize_t orig_data_size_show(struct device *dev,
		{
		struct zram *zram = dev_to_zram(dev);

		deprecated_attr_warn("orig_data_size");
		return scnprintf(buf, PAGE_SIZE, "%llu\n",
		(u64)(atomic64_read(&zram->stats.pages_stored)) << PAGE_SHIFT);
		}
		@@ -99,6 +111,7 @@ static ssize_t mem_used_total_show(struct device *dev,
		u64 val = 0;
		struct zram *zram = dev_to_zram(dev);

		deprecated_attr_warn("mem_used_total");
		down_read(&zram->init_lock);
		if (init_done(zram)) {
		struct zram_meta *meta = zram->meta;
		@@ -128,6 +141,7 @@ static ssize_t mem_limit_show(struct device *dev,
		u64 val;
		struct zram *zram = dev_to_zram(dev);

		deprecated_attr_warn("mem_limit");
		down_read(&zram->init_lock);
		val = zram->limit_pages;
		up_read(&zram->init_lock);
		@@ -159,6 +173,7 @@ static ssize_t mem_used_max_show(struct device *dev,
		u64 val = 0;
		struct zram *zram = dev_to_zram(dev);

		deprecated_attr_warn("mem_used_max");
		down_read(&zram->init_lock);
		if (init_done(zram))
		val = atomic_long_read(&zram->stats.max_used_pages);

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