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authorAngelo Ruocco <angeloruocco90@gmail.com>2019-05-21 10:01:54 +0200
committerJens Axboe <axboe@kernel.dk>2019-06-07 01:29:39 -0600
commit54b7b868e826b294687c439b68ec55fe20cafe5b (patch)
treeb313bb034660d32f62dc725718a373e214aceeca /kernel
parentc3e2219216c92919a6bd1711f340f5faa98695e6 (diff)
downloadlinux-54b7b868e826b294687c439b68ec55fe20cafe5b.tar.bz2
cgroup: let a symlink too be created with a cftype file
This commit enables a cftype to have a symlink (of any name) that points to the file associated with the cftype. Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup/cgroup.c33
1 files changed, 29 insertions, 4 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 426a0026225c..155048b0eca2 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1460,8 +1460,8 @@ struct cgroup *task_cgroup_from_root(struct task_struct *task,
static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
-static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
- char *buf)
+static char *cgroup_fill_name(struct cgroup *cgrp, const struct cftype *cft,
+ char *buf, bool write_link_name)
{
struct cgroup_subsys *ss = cft->ss;
@@ -1471,13 +1471,26 @@ static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
snprintf(buf, CGROUP_FILE_NAME_MAX, "%s%s.%s",
dbg, cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name,
- cft->name);
+ write_link_name ? cft->link_name : cft->name);
} else {
- strscpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
+ strscpy(buf, write_link_name ? cft->link_name : cft->name,
+ CGROUP_FILE_NAME_MAX);
}
return buf;
}
+static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
+ char *buf)
+{
+ return cgroup_fill_name(cgrp, cft, buf, false);
+}
+
+static char *cgroup_link_name(struct cgroup *cgrp, const struct cftype *cft,
+ char *buf)
+{
+ return cgroup_fill_name(cgrp, cft, buf, true);
+}
+
/**
* cgroup_file_mode - deduce file mode of a control file
* @cft: the control file in question
@@ -1636,6 +1649,9 @@ static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
}
kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
+ if (cft->flags & CFTYPE_SYMLINKED)
+ kernfs_remove_by_name(cgrp->kn,
+ cgroup_link_name(cgrp, cft, name));
}
/**
@@ -3821,6 +3837,7 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
{
char name[CGROUP_FILE_NAME_MAX];
struct kernfs_node *kn;
+ struct kernfs_node *kn_link;
struct lock_class_key *key = NULL;
int ret;
@@ -3851,6 +3868,14 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
spin_unlock_irq(&cgroup_file_kn_lock);
}
+ if (cft->flags & CFTYPE_SYMLINKED) {
+ kn_link = kernfs_create_link(cgrp->kn,
+ cgroup_link_name(cgrp, cft, name),
+ kn);
+ if (IS_ERR(kn_link))
+ return PTR_ERR(kn_link);
+ }
+
return 0;
}