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@xxxxxxxxxx>
---
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@xxxxxxxx>
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