From f14bf5f4f850ca39d1de1d0315e226bceb14db2f Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@kernel.org>
Date: Mon, 7 Apr 2014 15:38:21 -0700
Subject: zram: propagate error to user

When we initialized zcomp with single, we couldn't change
max_comp_streams without zram reset but current interface doesn't show
any error to user and even it changes max_comp_streams's value without
any effect so it would make user very confusing.

This patch prevents max_comp_streams's change when zcomp was initialized
as single zcomp and emit the error to user(ex, echo).

[akpm@linux-foundation.org: don't return with the lock held, per Sergey]
[fengguang.wu@intel.com: fix coccinelle warnings]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 Documentation/blockdev/zram.txt | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

(limited to 'Documentation')

diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index 7055bab..986b923 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -39,10 +39,11 @@ Note:
 In order to enable compression backend's multi stream support max_comp_streams
 must be initially set to desired concurrency level before ZRAM device
 initialisation. Once the device initialised as a single stream compression
-backend (max_comp_streams equals to 0) changing the value of max_comp_streams
-will not take any effect, because single stream compression backend implemented
-as a special case and does not support dynamic max_comp_streams. Only multi
-stream backend supports dynamic max_comp_streams adjustment.
+backend (max_comp_streams equals to 1), you will see error if you try to change
+the value of max_comp_streams because single stream compression backend
+implemented as a special case by lock overhead issue and does not support
+dynamic max_comp_streams. Only multi stream backend supports dynamic
+max_comp_streams adjustment.
 
 3) Select compression algorithm
 	Using comp_algorithm device attribute one can see available and
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