summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorDennis Zhou <dennis@kernel.org>2018-10-20 14:56:12 -0400
committerJens Axboe <axboe@kernel.dk>2018-10-20 15:39:55 -0600
commitd459d853c2edc793135e4bfa4e345c758f1cc859 (patch)
treebef29425e5ddb78a788cca764e926b4f5601f473
parentb2c3fa546705944e748666b474ffdaebaec0569f (diff)
downloadlinux-d459d853c2edc793135e4bfa4e345c758f1cc859.tar.bz2
blkcg: reassociate bios when make_request() is called recursively
When submitting a bio, multiple recursive calls to make_request() may occur. This causes the initial associate done in blkcg_bio_issue_check() to be incorrect and reference the prior request_queue. This introduces a helper to do reassociation when make_request() is recursively called. Fixes: a7b39b4e961c ("blkcg: always associate a bio with a blkg") Reported-by: Valdis Kletnieks <valdis.kletnieks@vt.edu> Signed-off-by: Dennis Zhou <dennis@kernel.org> Tested-by: Valdis Kletnieks <valdis.kletnieks@vt.edu> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--block/bio.c20
-rw-r--r--block/blk-core.c1
-rw-r--r--include/linux/bio.h3
3 files changed, 24 insertions, 0 deletions
diff --git a/block/bio.c b/block/bio.c
index 17a8b0aa7050..bbfeb4ee2892 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -2084,6 +2084,26 @@ int bio_associate_create_blkg(struct request_queue *q, struct bio *bio)
}
/**
+ * bio_reassociate_blkg - reassociate a bio with a blkg from q
+ * @q: request_queue where bio is going
+ * @bio: target bio
+ *
+ * When submitting a bio, multiple recursive calls to make_request() may occur.
+ * This causes the initial associate done in blkcg_bio_issue_check() to be
+ * incorrect and reference the prior request_queue. This performs reassociation
+ * when this situation happens.
+ */
+int bio_reassociate_blkg(struct request_queue *q, struct bio *bio)
+{
+ if (bio->bi_blkg) {
+ blkg_put(bio->bi_blkg);
+ bio->bi_blkg = NULL;
+ }
+
+ return bio_associate_create_blkg(q, bio);
+}
+
+/**
* bio_disassociate_task - undo bio_associate_current()
* @bio: target bio
*/
diff --git a/block/blk-core.c b/block/blk-core.c
index cdfabc5646da..3ed60723e242 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2433,6 +2433,7 @@ blk_qc_t generic_make_request(struct bio *bio)
if (q)
blk_queue_exit(q);
q = bio->bi_disk->queue;
+ bio_reassociate_blkg(q, bio);
flags = 0;
if (bio->bi_opf & REQ_NOWAIT)
flags = BLK_MQ_REQ_NOWAIT;
diff --git a/include/linux/bio.h b/include/linux/bio.h
index f447b0ebb288..b47c7f716731 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -514,6 +514,7 @@ int bio_associate_blkg(struct bio *bio, struct blkcg_gq *blkg);
int bio_associate_blkg_from_css(struct bio *bio,
struct cgroup_subsys_state *css);
int bio_associate_create_blkg(struct request_queue *q, struct bio *bio);
+int bio_reassociate_blkg(struct request_queue *q, struct bio *bio);
void bio_disassociate_task(struct bio *bio);
void bio_clone_blkg_association(struct bio *dst, struct bio *src);
#else /* CONFIG_BLK_CGROUP */
@@ -522,6 +523,8 @@ static inline int bio_associate_blkg_from_css(struct bio *bio,
{ return 0; }
static inline int bio_associate_create_blkg(struct request_queue *q,
struct bio *bio) { return 0; }
+static inline int bio_reassociate_blkg(struct request_queue *q, struct bio *bio)
+{ return 0; }
static inline void bio_disassociate_task(struct bio *bio) { }
static inline void bio_clone_blkg_association(struct bio *dst,
struct bio *src) { }