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Revert "blk-mq: Micro-optimize bt_get()"

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This reverts commit 52f7eb945f2ba62b324bb9ae16d945326a961dcf.

The optimization is only really safe for a single queue, otherwise
'bs' and 'bt' can indeed change, and if we don't do a finish_wait()
for each loop, we'll potentially change the wait structure and
corrupt task wait list.

Reported-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jens Axboe 2014-12-15 08:30:26 -07:00
parent 67e2c38838
commit 35d37c6635
1 changed files with 3 additions and 1 deletions
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4
block/blk-mq-tag.c
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@ -248,8 +248,8 @@ static int bt_get(struct blk_mq_alloc_data *data,
if (!(data->gfp & __GFP_WAIT))
return -1;
bs = bt_wait_ptr(bt, hctx);
do {
bs = bt_wait_ptr(bt, hctx);
prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE);
tag = __bt_get(hctx, bt, last_tag);
@ -285,6 +285,8 @@ static int bt_get(struct blk_mq_alloc_data *data,
hctx = data->hctx;
bt = &hctx->tags->bitmap_tags;
}
finish_wait(&bs->wait, &wait);
bs = bt_wait_ptr(bt, hctx);
} while (1);
finish_wait(&bs->wait, &wait);