zram: deprecate zram attrs sysfs nodes

[mirror_ubuntu-artful-kernel.git] / Documentation / blockdev / zram.txt

diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index 7920f4026d36608f5333c9dce2fdad8749f0237b..48a183e29988d968ee11172a2bd2f9726c4ad65b 100644 (file)
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -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