From: Angelo Ruocco <angeloruocc...@gmail.com> 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 <angeloruocc...@gmail.com> Signed-off-by: Paolo Valente <paolo.vale...@linaro.org> Signed-off-by: Jens Axboe <ax...@kernel.dk> https://jira.sw.ru/browse/PSBM-101019 (cherry-picked from 54b7b868e826b294687c439b68ec55fe20cafe5b) Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> Signed-off-by: Cyrill Gorcunov <gorcu...@virtuozzo.com> --- include/linux/cgroup-defs.h | 3 +++ kernel/cgroup/cgroup.c | 33 +++++++++++++++++++++++++++++---- 2 files changed, 32 insertions(+), 4 deletions(-) diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 583ce2bce98c..2ff9b68ad243 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -125,6 +125,8 @@ enum { */ CFTYPE_VE_WRITABLE = (1 << 15), + CFTYPE_SYMLINKED = (1 << 7), /* pointed to by symlink too */ + /* internal flags, do not use outside cgroup core proper */ __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */ __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */ @@ -552,6 +554,7 @@ struct cftype { * end of cftype array. */ char name[MAX_CFTYPE_NAME]; + char link_name[MAX_CFTYPE_NAME]; unsigned long private; /* diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 08b7cff7a1c3..74d0b503e696 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1471,8 +1471,8 @@ 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; @@ -1482,13 +1482,26 @@ 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 @@ -1647,6 +1660,9 @@ 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)); } /** @@ -4012,6 +4028,7 @@ 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; @@ -4042,6 +4059,14 @@ 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; } -- 2.31.1 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
