block: add missing group association in bio-cloning functions

commit 20bd723ec6a3261df5e02250cd3a1fbb09a343f2 upstream.

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")
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/block/bio.c b/block/bio.c
index d4d144363250f7dfe2e2ed41ed9fca7425c18c0a..46e2cc1d4016e450dff6273f6ef8ee8755985848 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -584,6 +584,8 @@ 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);
 
@@ -689,6 +691,8 @@ integrity_clone:
                }
        }
 
+       bio_clone_blkcg_association(bio, bio_src);
+
        return bio;
 }
 EXPORT_SYMBOL(bio_clone_bioset);
@@ -2014,6 +2018,17 @@ 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 9abe18763a7fb001632246fd712a64fdffcc0225..257bbdcb5df64582236bfc9be9f721f418e957a0 100644 (file)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2786,12 +2786,6 @@ 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 fbe47bc700bd014ca647b7b1d872c8e5ddd04618..42e4e3cbb001951dd7a52dfd4b0b0857db4f93bf 100644 (file)
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -527,11 +527,14 @@ 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