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authorDennis Zhou <dennis@kernel.org>2018-12-05 12:10:34 -0500
committerJens Axboe <axboe@kernel.dk>2018-12-07 22:26:37 -0700
commitfd42df305f804ddc0d5ac028e944784283b2f92d (patch)
treef10e4821b3dca25647f1eaf401b8f4529d0d2ade /Documentation/admin-guide
parent6a7f6d86a561473032287c8e4583eac5853c6efa (diff)
blkcg: associate writeback bios with a blkg
One of the goals of this series is to remove a separate reference to the css of the bio. This can and should be accessed via bio_blkcg(). In this patch, wbc_init_bio() now requires a bio to have a device associated with it. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/cgroup-v2.rst8
1 files changed, 5 insertions, 3 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 476722b7b636..baf19bf28385 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1879,8 +1879,10 @@ following two functions.
wbc_init_bio(@wbc, @bio)
Should be called for each bio carrying writeback data and
- associates the bio with the inode's owner cgroup. Can be
- called anytime between bio allocation and submission.
+ associates the bio with the inode's owner cgroup and the
+ corresponding request queue. This must be called after
+ a queue (device) has been associated with the bio and
+ before submission.
wbc_account_io(@wbc, @page, @bytes)
Should be called for each data segment being written out.
@@ -1899,7 +1901,7 @@ the configuration, the bio may be executed at a lower priority and if
the writeback session is holding shared resources, e.g. a journal
entry, may lead to priority inversion. There is no one easy solution
for the problem. Filesystems can try to work around specific problem
-cases by skipping wbc_init_bio() or using bio_associate_blkcg()
+cases by skipping wbc_init_bio() and using bio_associate_blkg()
directly.