bcache: cannot set writeback_running via sysfs if no writeback kthread created (f383ae30) · Commits · 戴 / test

"echo 1 > writeback_running" marks writeback_running even if no writeback kthread created as "d_strtoul(writeback_running)" will simply set dc-> writeback_running without checking the existence of dc->writeback_thread. Add check for setting writeback_running via sysfs: if no writeback kthread available, reject setting to 1. v2 -> v3: * Make message on wrong assignment more clear. * Print name of bcache device instead of name of backing device. Signed-off-by:

Shenghui Wang <shhuiw@foxmail.com> Signed-off-by:

Coly Li <colyli@suse.de> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

drivers/md/bcache/sysfs.c

+19 −2

Original line number	Diff line number	Diff line
		@@ -384,8 +384,25 @@ STORE(bch_cached_dev)
		mutex_lock(&bch_register_lock);
		size = __cached_dev_store(kobj, attr, buf, size);

		if (attr == &sysfs_writeback_running)
		if (attr == &sysfs_writeback_running) {
		/* dc->writeback_running changed in __cached_dev_store() */
		if (IS_ERR_OR_NULL(dc->writeback_thread)) {
		/*
		* reject setting it to 1 via sysfs if writeback
		* kthread is not created yet.
		*/
		if (dc->writeback_running) {
		dc->writeback_running = false;
		pr_err("%s: failed to run non-existent writeback thread",
		dc->disk.disk->disk_name);
		}
		} else
		/*
		* writeback kthread will check if dc->writeback_running
		* is true or false.
		*/
		bch_writeback_queue(dc);
		}

		if (attr == &sysfs_writeback_percent)
		if (!test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))

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