block: add missing group association in bio-cloning functions

When a bio is cloned, the newly created bio must be associated with
the same blkcg as the original bio (if BLK_CGROUP is enabled). If
this operation is not performed, then the new bio is not associated
with any group, and the group of the current task is returned when
the group of the bio is requested.

Depending on the cloning frequency, this may cause a large
percentage of the bios belonging to a given group to be treated
as if belonging to other groups (in most cases as if belonging to
the root group). The expected group isolation may thereby be broken.

This commit adds the missing association in bio-cloning functions.

Fixes: da2f0f74cf7d ("Btrfs: add support for blkio controllers")
Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Reviewed-by: Nikolay Borisov <kernel@kyup.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/bio.c b/block/bio.c
index 54ee3846c3a5e045b4f4578a11a1972f17336f6a..3f76a38a5e2d66f81fe78e4d3feffe825e3214eb 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -583,6 +583,8 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
        bio->bi_rw = bio_src->bi_rw;
        bio->bi_iter = bio_src->bi_iter;
        bio->bi_io_vec = bio_src->bi_io_vec;
+
+       bio_clone_blkcg_association(bio, bio_src);
 }
 EXPORT_SYMBOL(__bio_clone_fast);
 
@@ -687,6 +689,8 @@ integrity_clone:
                }
        }
 
+       bio_clone_blkcg_association(bio, bio_src);
+
        return bio;
 }
 EXPORT_SYMBOL(bio_clone_bioset);
@@ -2004,6 +2008,17 @@ void bio_disassociate_task(struct bio *bio)
        }
 }
 
+/**
+ * bio_clone_blkcg_association - clone blkcg association from src to dst bio
+ * @dst: destination bio
+ * @src: source bio
+ */
+void bio_clone_blkcg_association(struct bio *dst, struct bio *src)
+{
+       if (src->bi_css)
+               WARN_ON(bio_associate_blkcg(dst, src->bi_css));
+}
+
 #endif /* CONFIG_BLK_CGROUP */
 
 static void __init biovec_init_slabs(void)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index cee4cb99b8ce7b436c60f394b518e22256ecbf97..5850d79806f42cf100e91e8d3c02d3ca551d1839 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2697,12 +2697,6 @@ struct bio *btrfs_bio_clone(struct bio *bio, gfp_t gfp_mask)
                btrfs_bio->csum = NULL;
                btrfs_bio->csum_allocated = NULL;
                btrfs_bio->end_io = NULL;
-
-#ifdef CONFIG_BLK_CGROUP
-               /* FIXME, put this into bio_clone_bioset */
-               if (bio->bi_css)
-                       bio_associate_blkcg(new, bio->bi_css);
-#endif
        }
        return new;
 }

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 583c10810e323b0835fa856cda4930b901280989..e09a8895fc31d1a348606a29dd06e46425270595 100644 (file)
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -470,11 +470,14 @@ extern unsigned int bvec_nr_vecs(unsigned short idx);
 int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
 int bio_associate_current(struct bio *bio);
 void bio_disassociate_task(struct bio *bio);
+void bio_clone_blkcg_association(struct bio *dst, struct bio *src);
 #else  /* CONFIG_BLK_CGROUP */
 static inline int bio_associate_blkcg(struct bio *bio,
                        struct cgroup_subsys_state *blkcg_css) { return 0; }
 static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
 static inline void bio_disassociate_task(struct bio *bio) { }
+static inline void bio_clone_blkcg_association(struct bio *dst,
+                       struct bio *src) { }
 #endif /* CONFIG_BLK_CGROUP */
 
 #ifdef CONFIG_HIGHMEM