blk-cgroup: increase number of supported policies (01c5f85a) · Commits · 戴 / test

After merging the iolatency policy, we potentially now have 4 policies being registered, but only support 3. This causes one of them to fail loading. Takashi reports that BFQ no longer works for him, because it fails to load due to policy registration failure. Bump to 5 policies, and also add a warning for when we have exceeded the global amount. If we have to touch this again, we should switch to a dynamic scheme instead. Reported-by:

Takashi Iwai <tiwai@suse.de> Reviewed-by:

Jeff Moyer <jmoyer@redhat.com> Tested-by:

Takashi Iwai <tiwai@suse.de> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

block/blk-cgroup.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -1510,8 +1510,10 @@ int blkcg_policy_register(struct blkcg_policy *pol)
		for (i = 0; i < BLKCG_MAX_POLS; i++)
		if (!blkcg_policy[i])
		break;
		if (i >= BLKCG_MAX_POLS)
		if (i >= BLKCG_MAX_POLS) {
		pr_warn("blkcg_policy_register: BLKCG_MAX_POLS too small\n");
		goto err_unlock;
		}

		/* Make sure cpd/pd_alloc_fn and cpd/pd_free_fn in pairs */
		if ((!pol->cpd_alloc_fn ^ !pol->cpd_free_fn) \|\|

include/linux/blkdev.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -54,7 +54,7 @@ struct blk_stat_callback;
		* Maximum number of blkcg policies allowed to be registered concurrently.
		* Defined here to simplify include dependency.
		*/
		#define BLKCG_MAX_POLS 3
		#define BLKCG_MAX_POLS 5

		typedef void (rq_end_io_fn)(struct request *, blk_status_t);

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