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| author | Tejun Heo <tj@kernel.org> | 2014-05-13 12:16:21 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2014-05-13 12:16:21 -0400 |
| commit | b41686401e501430ffe93b575ef7959d2ecc6f2e (patch) | |
| tree | 9d38bb6b2878c3107aaad43ab53ac145c4ed9a9e /kernel | |
| parent | ec903c0c858e4963a9e0724bdcadfa837253341c (diff) | |
| download | lwn-b41686401e501430ffe93b575ef7959d2ecc6f2e.tar.gz lwn-b41686401e501430ffe93b575ef7959d2ecc6f2e.zip | |
cgroup: implement cftype->write()
During the recent conversion to kernfs, cftype's seq_file operations
are updated so that they are directly mapped to kernfs operations and
thus can fully access the associated kernfs and cgroup contexts;
however, write path hasn't seen similar updates and none of the
existing write operations has access to, for example, the associated
kernfs_open_file.
Let's introduce a new operation cftype->write() which maps directly to
the kernfs write operation and has access to all the arguments and
contexts. This will replace ->write_string() and ->trigger() and ease
manipulation of kernfs active protection from cgroup file operations.
Two accessors - of_cft() and of_css() - are introduced to enable
accessing the associated cgroup context from cftype->write() which
only takes kernfs_open_file for the context information. The
accessors for seq_file operations - seq_cft() and seq_css() - are
rewritten to wrap the of_ accessors.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 671d8a6dae37..a16f91d12f4e 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -283,11 +283,10 @@ static inline bool cgroup_is_dead(const struct cgroup *cgrp) return test_bit(CGRP_DEAD, &cgrp->flags); } -struct cgroup_subsys_state *seq_css(struct seq_file *seq) +struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) { - struct kernfs_open_file *of = seq->private; struct cgroup *cgrp = of->kn->parent->priv; - struct cftype *cft = seq_cft(seq); + struct cftype *cft = of_cft(of); /* * This is open and unprotected implementation of cgroup_css(). @@ -302,7 +301,7 @@ struct cgroup_subsys_state *seq_css(struct seq_file *seq) else return &cgrp->dummy_css; } -EXPORT_SYMBOL_GPL(seq_css); +EXPORT_SYMBOL_GPL(of_css); /** * cgroup_is_descendant - test ancestry @@ -1035,8 +1034,8 @@ static umode_t cgroup_file_mode(const struct cftype *cft) if (cft->read_u64 || cft->read_s64 || cft->seq_show) mode |= S_IRUGO; - if (cft->write_u64 || cft->write_s64 || cft->write_string || - cft->trigger) + if (cft->write_u64 || cft->write_s64 || cft->write || + cft->write_string || cft->trigger) mode |= S_IWUSR; return mode; @@ -2726,6 +2725,9 @@ static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, struct cgroup_subsys_state *css; int ret; + if (cft->write) + return cft->write(of, buf, nbytes, off); + /* * kernfs guarantees that a file isn't deleted with operations in * flight, which means that the matching css is and stays alive and |