loop: Only change blocksize when needed. (7e81f99a) · Commits · 戴 / test

Return early in loop_set_block_size() if the requested block size is identical to the one we already have; this avoids expensive calls to freeze the block queue. Reviewed-by:

Christoph Hellwig <hch@lst.de> Signed-off-by:

Martijn Coenen <maco@android.com> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

drivers/block/loop.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -1539,16 +1539,16 @@ static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
		if (arg < 512 \|\| arg > PAGE_SIZE \|\| !is_power_of_2(arg))
		return -EINVAL;

		if (lo->lo_queue->limits.logical_block_size != arg) {
		if (lo->lo_queue->limits.logical_block_size == arg)
		return 0;

		sync_blockdev(lo->lo_device);
		kill_bdev(lo->lo_device);
		}

		blk_mq_freeze_queue(lo->lo_queue);

		/* kill_bdev should have truncated all the pages */
		if (lo->lo_queue->limits.logical_block_size != arg &&
		lo->lo_device->bd_inode->i_mapping->nrpages) {
		if (lo->lo_device->bd_inode->i_mapping->nrpages) {
		err = -EAGAIN;
		pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
		__func__, lo->lo_number, lo->lo_file_name,

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