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authorZhang Yi <yi.zhang@huawei.com>2021-06-19 12:36:59 +0300
committerJens Axboe <axboe@kernel.dk>2021-06-22 00:03:41 +0300
commit1d0903d61e9645c6330b94247b96dd873dfc11c8 (patch)
treea46e127deb8156f8a2390770c36d0a070a126749 /block
parentfb926032b3209300f9dc454a36b8299582ae545c (diff)
downloadlinux-1d0903d61e9645c6330b94247b96dd873dfc11c8.tar.xz
blk-wbt: introduce a new disable state to prevent false positive by rwb_enabled()
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>
Diffstat (limited to 'block')
-rw-r--r--block/blk-wbt.c5
-rw-r--r--block/blk-wbt.h1
2 files changed, 4 insertions, 2 deletions
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index b363b0532704..0ce0883df3d6 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -77,7 +77,8 @@ 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)
@@ -701,7 +702,7 @@ 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 16bdc85b8df9..2eb01becde8c 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 {