block: remove per-disk debugfs files in blk_unregister_queue

The block debugfs files are created in blk_register_queue, which is
called by add_disk and use a naming scheme based on the disk_name.
After del_gendisk returns that name can be reused and thus we must not
leave these debugfs files around, otherwise the kernel is unhappy
and spews messages like:

	Directory XXXXX with parent 'block' already present!

and the newly created devices will not have working debugfs files.

Move the unregistration to blk_unregister_queue instead (which matches
the sysfs unregistration) to make sure the debugfs life time rules match
those of the disk name.

As part of the move also make sure the whole debugfs unregistration is
inside a single debugfs_mutex critical section.

Note that this breaks blktests block/002, which checks that the debugfs
directory has not been removed while blktests is running, but that
particular check should simply be removed from the test case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220614074827.458955-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index f0fcfe1387cbc3a18591e172780f18d97ce68cca..4d1ce9ef4318789e968586a3f5e6af4b5b80f3bf 100644 (file)
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -840,14 +840,6 @@ void blk_mq_debugfs_register_rqos(struct rq_qos *rqos)
        debugfs_create_files(rqos->debugfs_dir, rqos, rqos->ops->debugfs_attrs);
 }
 
-void blk_mq_debugfs_unregister_queue_rqos(struct request_queue *q)
-{
-       lockdep_assert_held(&q->debugfs_mutex);
-
-       debugfs_remove_recursive(q->rqos_debugfs_dir);
-       q->rqos_debugfs_dir = NULL;
-}
-
 void blk_mq_debugfs_register_sched_hctx(struct request_queue *q,
                                        struct blk_mq_hw_ctx *hctx)
 {

diff --git a/block/blk-mq-debugfs.h b/block/blk-mq-debugfs.h
index 771d4583287885df513bc072108e937e5fe8af9b..9c7d4b6117d41ed343dab8c20b1859da2b9c6f60 100644 (file)
--- a/block/blk-mq-debugfs.h
+++ b/block/blk-mq-debugfs.h
@@ -35,7 +35,6 @@ void blk_mq_debugfs_unregister_sched_hctx(struct blk_mq_hw_ctx *hctx);
 
 void blk_mq_debugfs_register_rqos(struct rq_qos *rqos);
 void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos);
-void blk_mq_debugfs_unregister_queue_rqos(struct request_queue *q);
 #else
 static inline void blk_mq_debugfs_register(struct request_queue *q)
 {
@@ -82,10 +81,6 @@ static inline void blk_mq_debugfs_register_rqos(struct rq_qos *rqos)
 static inline void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos)
 {
 }
-
-static inline void blk_mq_debugfs_unregister_queue_rqos(struct request_queue *q)
-{
-}
 #endif
 
 #ifdef CONFIG_BLK_DEBUG_FS_ZONED

diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c
index 249a6f05dd3bd81b7157553ca1f305db4e2ec0d2..d3a75693adbf4ddf9ffb94b07d4302ffcd2ea0cb 100644 (file)
--- a/block/blk-rq-qos.c
+++ b/block/blk-rq-qos.c
@@ -294,10 +294,6 @@ void rq_qos_wait(struct rq_wait *rqw, void *private_data,
 
 void rq_qos_exit(struct request_queue *q)
 {
-       mutex_lock(&q->debugfs_mutex);
-       blk_mq_debugfs_unregister_queue_rqos(q);
-       mutex_unlock(&q->debugfs_mutex);
-
        while (q->rq_qos) {
                struct rq_qos *rqos = q->rq_qos;
                q->rq_qos = rqos->next;

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 6e4801b217a792cf9b01354efe771d3a61d60def..9b905e9443e49606e09311757985eddeebc6cbef 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -779,13 +779,6 @@ static void blk_release_queue(struct kobject *kobj)
        if (queue_is_mq(q))
                blk_mq_release(q);
 
-       mutex_lock(&q->debugfs_mutex);
-       blk_trace_shutdown(q);
-       debugfs_remove_recursive(q->debugfs_dir);
-       q->debugfs_dir = NULL;
-       q->sched_debugfs_dir = NULL;
-       mutex_unlock(&q->debugfs_mutex);
-
        bioset_exit(&q->bio_split);
 
        if (blk_queue_has_srcu(q))
@@ -946,8 +939,15 @@ void blk_unregister_queue(struct gendisk *disk)
        /* Now that we've deleted all child objects, we can delete the queue. */
        kobject_uevent(&q->kobj, KOBJ_REMOVE);
        kobject_del(&q->kobj);
-
        mutex_unlock(&q->sysfs_dir_lock);
 
+       mutex_lock(&q->debugfs_mutex);
+       blk_trace_shutdown(q);
+       debugfs_remove_recursive(q->debugfs_dir);
+       q->debugfs_dir = NULL;
+       q->sched_debugfs_dir = NULL;
+       q->rqos_debugfs_dir = NULL;
+       mutex_unlock(&q->debugfs_mutex);
+
        kobject_put(&disk_to_dev(disk)->kobj);
 }