zram: deprecate zram attrs sysfs nodes
Add Documentation/ABI/obsolete/sysfs-block-zram file and list obsolete and deprecated attributes there. The patch also adds additional information to zram documentation and describes the basic strategy: - the existing RW nodes will be downgraded to WO nodes (in 4.11) - deprecated RO sysfs nodes will eventually be removed (in 4.11) Users will be additionally notified about deprecated attr usage by pr_warn_once() (added to every deprecated attr _show()), as suggested by Minchan Kim. User space is advised to use zram<id>/stat, zram<id>/io_stat and zram<id>/mm_stat files. Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reported-by: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Linus Torvalds
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4f2109f608
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8f7d282c71
@@ -128,6 +128,22 @@ mem_limit RW the maximum amount of memory ZRAM can use to store
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num_migrated RO the number of objects migrated migrated by compaction
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WARNING
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=======
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per-stat sysfs attributes are considered to be deprecated.
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The basic strategy is:
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-- the existing RW nodes will be downgraded to WO nodes (in linux 4.11)
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-- deprecated RO sysfs nodes will eventually be removed (in linux 4.11)
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The list of deprecated attributes can be found here:
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Documentation/ABI/obsolete/sysfs-block-zram
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Basically, every attribute that has its own read accessible sysfs node
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(e.g. num_reads) *AND* is accessible via one of the stat files (zram<id>/stat
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or zram<id>/io_stat or zram<id>/mm_stat) is considered to be deprecated.
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User space is advised to use the following files to read the device statistics.
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File /sys/block/zram<id>/stat
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Represents block layer statistics. Read Documentation/block/stat.txt for
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