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>
This commit is contained in:
Sergey Senozhatsky
2015-04-15 16:16:09 -07:00
committed by Linus Torvalds
parent 4f2109f608
commit 8f7d282c71
3 changed files with 150 additions and 0 deletions
+16
View File
@@ -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