Match the locking order used by the core block code by only freezing the queue after taking the limits lock using the queue_limits_commit_update_frozen helper and document the callers that do not freeze the queue at all. Signed-off-by: Christoph Hellwig <hch@xxxxxx> --- drivers/block/loop.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 560d6d5879d6..15e486baa223 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -311,6 +311,13 @@ static void loop_clear_limits(struct loop_device *lo, int mode) lim.discard_granularity = 0; } + /* + * XXX: this updates the queue limits without freezing the queue, which + * is against the locking protocol and dangerous. But we can't just + * freeze the queue as we're inside the ->queue_rq method here. So this + * should move out into a workqueue unless we get the file operations to + * advertise if they support specific fallocate operations. + */ queue_limits_commit_update(lo->lo_queue, &lim); } @@ -1091,6 +1098,7 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode, lim = queue_limits_start_update(lo->lo_queue); loop_update_limits(lo, &lim, config->block_size); + /* No need to freeze the queue as the device isn't bound yet. */ error = queue_limits_commit_update(lo->lo_queue, &lim); if (error) goto out_unlock; @@ -1151,7 +1159,12 @@ static void __loop_clr_fd(struct loop_device *lo) lo->lo_sizelimit = 0; memset(lo->lo_file_name, 0, LO_NAME_SIZE); - /* reset the block size to the default */ + /* + * Reset the block size to the default. + * + * No queue freezing needed because this is called from the final + * ->release call only, so there can't be any outstanding I/O. + */ lim = queue_limits_start_update(lo->lo_queue); lim.logical_block_size = SECTOR_SIZE; lim.physical_block_size = SECTOR_SIZE; @@ -1471,9 +1484,10 @@ static int loop_set_block_size(struct loop_device *lo, unsigned long arg) sync_blockdev(lo->lo_device); invalidate_bdev(lo->lo_device); - blk_mq_freeze_queue(lo->lo_queue); lim = queue_limits_start_update(lo->lo_queue); loop_update_limits(lo, &lim, arg); + + blk_mq_freeze_queue(lo->lo_queue); err = queue_limits_commit_update(lo->lo_queue, &lim); loop_update_dio(lo); blk_mq_unfreeze_queue(lo->lo_queue); -- 2.45.2
