[PATCH BUGFIX] block: add missing group association in bio-cloning functions

[PATCH BUGFIX] block: add missing group association in bio-cloning functions

[Paolo Valente]

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.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
 block/bio.c          | 17 +++++++++++++++++
 fs/btrfs/extent_io.c |  6 ------
 include/linux/bio.h  |  2 ++
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 807d25e..e9b136a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -622,6 +622,8 @@ struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
 		}
 	}
 
+	bio_clone_blkcg_association(b, bio);
+
 	return b;
 }
 EXPORT_SYMBOL(bio_clone_fast);
@@ -695,6 +697,8 @@ integrity_clone:
 		}
 	}
 
+	bio_clone_blkcg_association(bio, bio_src);
+
 	return bio;
 }
 EXPORT_SYMBOL(bio_clone_bioset);
@@ -1811,6 +1815,8 @@ struct bio *bio_split(struct bio *bio, int sectors,
 
 	bio_advance(bio, split->bi_iter.bi_size);
 
+	bio_clone_blkcg_association(split, bio);
+
 	return split;
 }
 EXPORT_SYMBOL(bio_split);
@@ -2016,6 +2022,17 @@ 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 d247fc0..19f6739 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2686,12 +2686,6 @@ 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 6b7481f..a9ff116 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -527,11 +527,13 @@ 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) { }
+void bio_clone_blkcg_association(struct bio *dst, struct bio *src) { return 0; }
 #endif	/* CONFIG_BLK_CGROUP */
 
 #ifdef CONFIG_HIGHMEM
-- 
1.9.1

Re: [PATCH BUGFIX] block: add missing group association in bio-cloning functions

[Tejun Heo]

On Tue, May 10, 2016 at 10:23:41PM +0200, Paolo Valente wrote:
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index 6b7481f..a9ff116 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -527,11 +527,13 @@ 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) { }
> +void bio_clone_blkcg_association(struct bio *dst, struct bio *src) { return 0; }
   ^
   static inline

-- 
tejun

[PATCH BUGFIX V2] block: add missing group association in bio-cloning functions

[Paolo Valente]

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.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
 block/bio.c          | 17 +++++++++++++++++
 fs/btrfs/extent_io.c |  6 ------
 include/linux/bio.h  |  3 +++
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 807d25e..e9b136a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -622,6 +622,8 @@ struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
 		}
 	}
 
+	bio_clone_blkcg_association(b, bio);
+
 	return b;
 }
 EXPORT_SYMBOL(bio_clone_fast);
@@ -695,6 +697,8 @@ integrity_clone:
 		}
 	}
 
+	bio_clone_blkcg_association(bio, bio_src);
+
 	return bio;
 }
 EXPORT_SYMBOL(bio_clone_bioset);
@@ -1811,6 +1815,8 @@ struct bio *bio_split(struct bio *bio, int sectors,
 
 	bio_advance(bio, split->bi_iter.bi_size);
 
+	bio_clone_blkcg_association(split, bio);
+
 	return split;
 }
 EXPORT_SYMBOL(bio_split);
@@ -2016,6 +2022,17 @@ 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 d247fc0..19f6739 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2686,12 +2686,6 @@ 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 6b7481f..16cbe59 100644
--- 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) { return 0; }
 #endif	/* CONFIG_BLK_CGROUP */
 
 #ifdef CONFIG_HIGHMEM
-- 
1.9.1

Re: [PATCH BUGFIX V2] block: add missing group association in bio-cloning functions

[Tejun Heo]

On Tue, May 10, 2016 at 11:02:12PM +0200, Paolo Valente wrote:
> 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.
> 
> Signed-off-by: Paolo Valente <paolo.valente@linaro.org>

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun

Re: [PATCH BUGFIX V2] block: add missing group association in bio-cloning functions

[Jeff Moyer]

Paolo Valente <paolo.valente@linaro.org> writes:

> diff --git a/block/bio.c b/block/bio.c
> index 807d25e..e9b136a 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -622,6 +622,8 @@ struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
>  		}
>  	}
>  
> +	bio_clone_blkcg_association(b, bio);
> +
>  	return b;
>  }
>  EXPORT_SYMBOL(bio_clone_fast);
> @@ -695,6 +697,8 @@ integrity_clone:
>  		}
>  	}
>  
> +	bio_clone_blkcg_association(bio, bio_src);
> +
>  	return bio;
>  }
>  EXPORT_SYMBOL(bio_clone_bioset);
> @@ -1811,6 +1815,8 @@ struct bio *bio_split(struct bio *bio, int sectors,
>  
>  	bio_advance(bio, split->bi_iter.bi_size);
>  
> +	bio_clone_blkcg_association(split, bio);
> +

Hi, Paolo,

Did you test this?  bio_split calls bio_clone_bioset or bio_clone_fast,
so I'd be surprised if you didn't trigger that newly added warning.  :-)
Please remove the bio_split call site.

Cheers,
Jeff

Re: [PATCH BUGFIX V2] block: add missing group association in bio-cloning functions

[Paolo]

Il 10/05/2016 23:34, Jeff Moyer ha scritto:
> Paolo Valente <paolo.valente@linaro.org> writes:
>
>> diff --git a/block/bio.c b/block/bio.c
>> index 807d25e..e9b136a 100644
>> --- a/block/bio.c
>> +++ b/block/bio.c
>> @@ -622,6 +622,8 @@ struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
>>   		}
>>   	}
>>
>> +	bio_clone_blkcg_association(b, bio);
>> +
>>   	return b;
>>   }
>>   EXPORT_SYMBOL(bio_clone_fast);
>> @@ -695,6 +697,8 @@ integrity_clone:
>>   		}
>>   	}
>>
>> +	bio_clone_blkcg_association(bio, bio_src);
>> +
>>   	return bio;
>>   }
>>   EXPORT_SYMBOL(bio_clone_bioset);
>> @@ -1811,6 +1815,8 @@ struct bio *bio_split(struct bio *bio, int sectors,
>>
>>   	bio_advance(bio, split->bi_iter.bi_size);
>>
>> +	bio_clone_blkcg_association(split, bio);
>> +
>
> Hi, Paolo,
>
> Did you test this?  bio_split calls bio_clone_bioset or bio_clone_fast,
> so I'd be surprised if you didn't trigger that newly added warning.  :-)

Of course I didn't check the kernel log ...

I hope next version will not introduce more bugs than it will fix.

Thanks,
Paolo
> Please remove the bio_split call site.
>
> Cheers,
> Jeff
>

[PATCH BUGFIX V3] block: add missing group association in bio-cloning functions

[Paolo Valente]

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.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
 block/bio.c          | 15 +++++++++++++++
 fs/btrfs/extent_io.c |  6 ------
 include/linux/bio.h  |  3 +++
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 807d25e..5eaf0b5 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -622,6 +622,8 @@ struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs)
 		}
 	}
 
+	bio_clone_blkcg_association(b, bio);
+
 	return b;
 }
 EXPORT_SYMBOL(bio_clone_fast);
@@ -695,6 +697,8 @@ integrity_clone:
 		}
 	}
 
+	bio_clone_blkcg_association(bio, bio_src);
+
 	return bio;
 }
 EXPORT_SYMBOL(bio_clone_bioset);
@@ -2016,6 +2020,17 @@ 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 d247fc0..19f6739 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2686,12 +2686,6 @@ 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 6b7481f..16cbe59 100644
--- 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) { return 0; }
 #endif	/* CONFIG_BLK_CGROUP */
 
 #ifdef CONFIG_HIGHMEM
-- 
1.9.1

Re: [PATCH BUGFIX V3] block: add missing group association in bio-cloning functions

[Nikolay Borisov]

On 05/11/2016 01:01 AM, Paolo Valente wrote:
> 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.
> 
> Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
> ---
>  block/bio.c          | 15 +++++++++++++++
>  fs/btrfs/extent_io.c |  6 ------
>  include/linux/bio.h  |  3 +++
>  3 files changed, 18 insertions(+), 6 deletions(-)
> 

Just for reference something like that was already proposed (and tested)
before, though it never got merged :

https://www.redhat.com/archives/dm-devel/2016-March/msg00007.html

So you might also want to patch __bio_clone_fast to also apply this for
dm backed devices.

Otherwise:

Reviewed-by: Nikolay Borisov <kernel@kyup.com>

Re: [PATCH BUGFIX V3] block: add missing group association in bio-cloning functions

[Nikolay Borisov]

On 05/11/2016 09:38 AM, Nikolay Borisov wrote:
> 
> 
> On 05/11/2016 01:01 AM, Paolo Valente wrote:
>> 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.
>>
>> Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
>> ---
>>  block/bio.c          | 15 +++++++++++++++
>>  fs/btrfs/extent_io.c |  6 ------
>>  include/linux/bio.h  |  3 +++
>>  3 files changed, 18 insertions(+), 6 deletions(-)
>>
> 
> Just for reference something like that was already proposed (and tested)
> before, though it never got merged :
> 
> https://www.redhat.com/archives/dm-devel/2016-March/msg00007.html
> 
> So you might also want to patch __bio_clone_fast to also apply this for
> dm backed devices.

Right, to correct myself: You might want to move the association to
__blk_clone_fast that way you are also covering dm devices as well as
users of bio_clone_fast.


> 
> Otherwise:
> 
> Reviewed-by: Nikolay Borisov <kernel@kyup.com>
> 

Re: [PATCH BUGFIX V3] block: add missing group association in bio-cloning functions

[Paolo]

Il 11/05/2016 08:43, Nikolay Borisov ha scritto:
>
>
> On 05/11/2016 09:38 AM, Nikolay Borisov wrote:
>>
>>
>> On 05/11/2016 01:01 AM, Paolo Valente wrote:
>>> 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.
>>>
>>> Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
>>> ---
>>>   block/bio.c          | 15 +++++++++++++++
>>>   fs/btrfs/extent_io.c |  6 ------
>>>   include/linux/bio.h  |  3 +++
>>>   3 files changed, 18 insertions(+), 6 deletions(-)
>>>
>>
>> Just for reference something like that was already proposed (and tested)
>> before, though it never got merged :
>>
>> https://www.redhat.com/archives/dm-devel/2016-March/msg00007.html
>>
>> So you might also want to patch __bio_clone_fast to also apply this for
>> dm backed devices.
>
> Right, to correct myself: You might want to move the association to
> __blk_clone_fast that way you are also covering dm devices as well as
> users of bio_clone_fast.
>

Definitely (I didn't do that in the first place, because I worried
only about doing the association when bio_clone_fast was certainly
successful).

I'm sending a fresh patch.

Thanks,
Paolo

>
>>
>> Otherwise:
>>
>> Reviewed-by: Nikolay Borisov <kernel@kyup.com>
>>

[PATCH BUGFIX V4] block: add missing group association in bio-cloning functions

[Paolo Valente]

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.

Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Reviewed-by: Nikolay Borisov <kernel@kyup.com>
---
Tejun: I didn't add also your Ack, just because this version is slightly
different from the one you acked.
---
 block/bio.c          | 15 +++++++++++++++
 fs/btrfs/extent_io.c |  6 ------
 include/linux/bio.h  |  3 +++
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 807d25e..89f517c 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -590,6 +590,8 @@ 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);
 
@@ -695,6 +697,8 @@ integrity_clone:
 		}
 	}
 
+	bio_clone_blkcg_association(bio, bio_src);
+
 	return bio;
 }
 EXPORT_SYMBOL(bio_clone_bioset);
@@ -2016,6 +2020,17 @@ 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 d247fc0..19f6739 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2686,12 +2686,6 @@ 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 6b7481f..16cbe59 100644
--- 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) { return 0; }
 #endif	/* CONFIG_BLK_CGROUP */
 
 #ifdef CONFIG_HIGHMEM
-- 
1.9.1

Re: [PATCH BUGFIX V4] block: add missing group association in bio-cloning functions

[Tejun Heo]

On Wed, May 11, 2016 at 11:28:04AM +0200, Paolo Valente wrote:
> 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.
> 
> Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
> Reviewed-by: Nikolay Borisov <kernel@kyup.com>

 Acked-by: Tejun Heo <tj@kernel.org>

It prolly should also have the following tags

Fixes: da2f0f74cf7d ("Btrfs: add support for blkio controllers")
Cc: stable@vger.kernel.org # v4.3+

Thanks.

-- 
tejun

Re: [PATCH BUGFIX V4] block: add missing group association in bio-cloning functions

[Jeff Moyer]

Paolo Valente <paolo.valente@linaro.org> writes:

> 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.
>
> Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
> Reviewed-by: Nikolay Borisov <kernel@kyup.com>

I think this one's golden!  Thanks, Paolo!

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


> ---
> Tejun: I didn't add also your Ack, just because this version is slightly
> different from the one you acked.
> ---
>  block/bio.c          | 15 +++++++++++++++
>  fs/btrfs/extent_io.c |  6 ------
>  include/linux/bio.h  |  3 +++
>  3 files changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index 807d25e..89f517c 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -590,6 +590,8 @@ 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);
>  
> @@ -695,6 +697,8 @@ integrity_clone:
>  		}
>  	}
>  
> +	bio_clone_blkcg_association(bio, bio_src);
> +
>  	return bio;
>  }
>  EXPORT_SYMBOL(bio_clone_bioset);
> @@ -2016,6 +2020,17 @@ 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 d247fc0..19f6739 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -2686,12 +2686,6 @@ 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 6b7481f..16cbe59 100644
> --- 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) { return 0; }
>  #endif	/* CONFIG_BLK_CGROUP */
>  
>  #ifdef CONFIG_HIGHMEM

Re: [PATCH BUGFIX V4] block: add missing group association in bio-cloning functions

[Paolo]

Jens,
are you picking this fix?

Thanks,
Paolo

Il 13/05/2016 22:42, Jeff Moyer ha scritto:
> Paolo Valente <paolo.valente@linaro.org> writes:
>
>> 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.
>>
>> Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
>> Reviewed-by: Nikolay Borisov <kernel@kyup.com>
>
> I think this one's golden!  Thanks, Paolo!
>
> Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
>
>
>> ---
>> Tejun: I didn't add also your Ack, just because this version is slightly
>> different from the one you acked.
>> ---
>>   block/bio.c          | 15 +++++++++++++++
>>   fs/btrfs/extent_io.c |  6 ------
>>   include/linux/bio.h  |  3 +++
>>   3 files changed, 18 insertions(+), 6 deletions(-)
>>
>> diff --git a/block/bio.c b/block/bio.c
>> index 807d25e..89f517c 100644
>> --- a/block/bio.c
>> +++ b/block/bio.c
>> @@ -590,6 +590,8 @@ 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);
>>
>> @@ -695,6 +697,8 @@ integrity_clone:
>>   		}
>>   	}
>>
>> +	bio_clone_blkcg_association(bio, bio_src);
>> +
>>   	return bio;
>>   }
>>   EXPORT_SYMBOL(bio_clone_bioset);
>> @@ -2016,6 +2020,17 @@ 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 d247fc0..19f6739 100644
>> --- a/fs/btrfs/extent_io.c
>> +++ b/fs/btrfs/extent_io.c
>> @@ -2686,12 +2686,6 @@ 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 6b7481f..16cbe59 100644
>> --- 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) { return 0; }
>>   #endif	/* CONFIG_BLK_CGROUP */
>>
>>   #ifdef CONFIG_HIGHMEM

[PATCH BUGFIX V4] block: add missing group association in bio-cloning functions

[Paolo Valente]

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>
---
 block/bio.c          | 15 +++++++++++++++
 fs/btrfs/extent_io.c |  6 ------
 include/linux/bio.h  |  3 +++
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 0e4aa42..4623869 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -579,6 +579,8 @@ 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);
 
@@ -684,6 +686,8 @@ integrity_clone:
 		}
 	}
 
+	bio_clone_blkcg_association(bio, bio_src);
+
 	return bio;
 }
 EXPORT_SYMBOL(bio_clone_bioset);
@@ -2005,6 +2009,17 @@ 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 75533ad..92fe3f8 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2696,12 +2696,6 @@ 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 9faebf7..c9403b7 100644
--- 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) { return 0; }
 #endif	/* CONFIG_BLK_CGROUP */
 
 #ifdef CONFIG_HIGHMEM
-- 
1.9.1

Re: [PATCH BUGFIX V4] block: add missing group association in bio-cloning functions

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 2594 bytes --]

Hi,

[auto build test WARNING on block/for-next]
[also build test WARNING on v4.7 next-20160726]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Paolo-Valente/block-add-missing-group-association-in-bio-cloning-functions/20160727-005044
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
config: x86_64-randconfig-x015-201630 (attached as .config)
compiler: gcc-6 (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   In file included from block/bio.c:20:0:
   include/linux/bio.h: In function 'bio_clone_blkcg_association':
>> include/linux/bio.h:480:30: warning: 'return' with a value, in function returning void
       struct bio *src) { return 0; }
                                 ^
   include/linux/bio.h:479:20: note: declared here
    static inline void bio_clone_blkcg_association(struct bio *dst,
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~

vim +/return +480 include/linux/bio.h

   464	void zero_fill_bio(struct bio *bio);
   465	extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
   466	extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
   467	extern unsigned int bvec_nr_vecs(unsigned short idx);
   468	
   469	#ifdef CONFIG_BLK_CGROUP
   470	int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css);
   471	int bio_associate_current(struct bio *bio);
   472	void bio_disassociate_task(struct bio *bio);
   473	void bio_clone_blkcg_association(struct bio *dst, struct bio *src);
   474	#else	/* CONFIG_BLK_CGROUP */
   475	static inline int bio_associate_blkcg(struct bio *bio,
   476				struct cgroup_subsys_state *blkcg_css) { return 0; }
   477	static inline int bio_associate_current(struct bio *bio) { return -ENOENT; }
   478	static inline void bio_disassociate_task(struct bio *bio) { }
   479	static inline void bio_clone_blkcg_association(struct bio *dst,
 > 480				struct bio *src) { return 0; }
   481	#endif	/* CONFIG_BLK_CGROUP */
   482	
   483	#ifdef CONFIG_HIGHMEM
   484	/*
   485	 * remember never ever reenable interrupts between a bvec_kmap_irq and
   486	 * bvec_kunmap_irq!
   487	 */
   488	static inline char *bvec_kmap_irq(struct bio_vec *bvec, unsigned long *flags)

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 26155 bytes --]

[PATCH BUGFIX V5] block: add missing group association in bio-cloning functions

[Paolo Valente]

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>
---
Fixed a compilation issue reported by kbuild test robot
---
 block/bio.c          | 15 +++++++++++++++
 fs/btrfs/extent_io.c |  6 ------
 include/linux/bio.h  |  3 +++
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 0e4aa42..4623869 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -579,6 +579,8 @@ 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);
 
@@ -684,6 +686,8 @@ integrity_clone:
 		}
 	}
 
+	bio_clone_blkcg_association(bio, bio_src);
+
 	return bio;
 }
 EXPORT_SYMBOL(bio_clone_bioset);
@@ -2005,6 +2009,17 @@ 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 75533ad..92fe3f8 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2696,12 +2696,6 @@ 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 9faebf7..75fadd2 100644
--- 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
-- 
1.9.1

Re: [PATCH BUGFIX V5] block: add missing group association in bio-cloning functions

[Jens Axboe]

On 07/26/2016 11:22 PM, Paolo Valente wrote:
> 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.

Added for 4.8, thanks.

-- 
Jens Axboe