lkml.org 
[lkml]   [2021]   [Jul]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.19 117/421] blk-wbt: introduce a new disable state to prevent false positive by rwb_enabled()
    Date
    From: Zhang Yi <yi.zhang@huawei.com>

    [ Upstream commit 1d0903d61e9645c6330b94247b96dd873dfc11c8 ]

    Now that we disable wbt by simply zero out rwb->wb_normal in
    wbt_disable_default() when switch elevator to bfq, but it's not safe
    because it will become false positive if we change queue depth. If it
    become false positive between wbt_wait() and wbt_track() when submit
    write request, it will lead to drop rqw->inflight to -1 in wbt_done(),
    which will end up trigger IO hung. Fix this issue by introduce a new
    state which mean the wbt was disabled.

    Fixes: a79050434b45 ("blk-rq-qos: refactor out common elements of blk-wbt")
    Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
    Link: https://lore.kernel.org/r/20210619093700.920393-2-yi.zhang@huawei.com
    Signed-off-by: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    block/blk-wbt.c | 5 +++--
    block/blk-wbt.h | 1 +
    2 files changed, 4 insertions(+), 2 deletions(-)

    diff --git a/block/blk-wbt.c b/block/blk-wbt.c
    index 50f2abfa1a60..08623f37617f 100644
    --- a/block/blk-wbt.c
    +++ b/block/blk-wbt.c
    @@ -76,7 +76,8 @@ enum {

    static inline bool rwb_enabled(struct rq_wb *rwb)
    {
    - return rwb && rwb->wb_normal != 0;
    + return rwb && rwb->enable_state != WBT_STATE_OFF_DEFAULT &&
    + rwb->wb_normal != 0;
    }

    static void wb_timestamp(struct rq_wb *rwb, unsigned long *var)
    @@ -764,7 +765,7 @@ void wbt_disable_default(struct request_queue *q)
    rwb = RQWB(rqos);
    if (rwb->enable_state == WBT_STATE_ON_DEFAULT) {
    blk_stat_deactivate(rwb->cb);
    - rwb->wb_normal = 0;
    + rwb->enable_state = WBT_STATE_OFF_DEFAULT;
    }
    }
    EXPORT_SYMBOL_GPL(wbt_disable_default);
    diff --git a/block/blk-wbt.h b/block/blk-wbt.h
    index f47218d5b3b2..dd0d0f297d1e 100644
    --- a/block/blk-wbt.h
    +++ b/block/blk-wbt.h
    @@ -34,6 +34,7 @@ enum {
    enum {
    WBT_STATE_ON_DEFAULT = 1,
    WBT_STATE_ON_MANUAL = 2,
    + WBT_STATE_OFF_DEFAULT
    };

    struct rq_wb {
    --
    2.30.2


    \
     
     \ /
      Last update: 2021-07-19 18:40    [W:4.171 / U:0.028 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site