From 2b2da2f6dc80e1299586f7e046a071809d5dee7f Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Wed, 12 Oct 2022 17:40:34 +0800 Subject: [PATCH] blk-iocost: prevent configuration update concurrent with io throttling This won't cause any severe problem currently, however, this doesn't seems appropriate: 1) 'ioc->params' is read from multiple places without holding 'ioc->lock', unexpected value might be read if writing it concurrently. 2) If configuration is changed while io is throttling, the functionality might be affected. For example, if module params is updated and cost becomes smaller, waiting for timer that is caculated under old configuration is not appropriate. Signed-off-by: Yu Kuai Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20221012094035.390056-4-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe --- block/blk-iocost.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) diff --git a/block/blk-iocost.c b/block/blk-iocost.c index 6d36a4bd4382..5acc5f13bbd6 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -3187,6 +3187,9 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input, ioc = q_to_ioc(disk->queue); } + blk_mq_freeze_queue(disk->queue); + blk_mq_quiesce_queue(disk->queue); + spin_lock_irq(&ioc->lock); memcpy(qos, ioc->params.qos, sizeof(qos)); enable = ioc->enabled; @@ -3278,10 +3281,17 @@ static ssize_t ioc_qos_write(struct kernfs_open_file *of, char *input, ioc_refresh_params(ioc, true); spin_unlock_irq(&ioc->lock); + blk_mq_unquiesce_queue(disk->queue); + blk_mq_unfreeze_queue(disk->queue); + blkdev_put_no_open(bdev); return nbytes; einval: spin_unlock_irq(&ioc->lock); + + blk_mq_unquiesce_queue(disk->queue); + blk_mq_unfreeze_queue(disk->queue); + ret = -EINVAL; err: blkdev_put_no_open(bdev); @@ -3336,6 +3346,7 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input, size_t nbytes, loff_t off) { struct block_device *bdev; + struct request_queue *q; struct ioc *ioc; u64 u[NR_I_LCOEFS]; bool user; @@ -3346,14 +3357,18 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input, if (IS_ERR(bdev)) return PTR_ERR(bdev); - ioc = q_to_ioc(bdev_get_queue(bdev)); + q = bdev_get_queue(bdev); + ioc = q_to_ioc(q); if (!ioc) { ret = blk_iocost_init(bdev->bd_disk); if (ret) goto err; - ioc = q_to_ioc(bdev_get_queue(bdev)); + ioc = q_to_ioc(q); } + blk_mq_freeze_queue(q); + blk_mq_quiesce_queue(q); + spin_lock_irq(&ioc->lock); memcpy(u, ioc->params.i_lcoefs, sizeof(u)); user = ioc->user_cost_model; @@ -3402,11 +3417,18 @@ static ssize_t ioc_cost_model_write(struct kernfs_open_file *of, char *input, ioc_refresh_params(ioc, true); spin_unlock_irq(&ioc->lock); + blk_mq_unquiesce_queue(q); + blk_mq_unfreeze_queue(q); + blkdev_put_no_open(bdev); return nbytes; einval: spin_unlock_irq(&ioc->lock); + + blk_mq_unquiesce_queue(q); + blk_mq_unfreeze_queue(q); + ret = -EINVAL; err: blkdev_put_no_open(bdev);