cgroup/bfq: revert bfq.weight symlink change

There's some discussion on how to do this the best, and Tejun prefers
that BFQ just create the file itself instead of having cgroups support
a symlink feature.

Hence revert commit 54b7b868e826 and 19e9da9e86c4 for 5.2, and this
can be done properly for 5.3.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 6 insertions, 36 deletions

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 59f46904cb11..b3796a40a61a 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -1046,8 +1046,7 @@ struct blkcg_policy blkcg_policy_bfq = {
 struct cftype bfq_blkcg_legacy_files[] = {
         {
                 .name = "bfq.weight",
-                .link_name = "weight",
-                .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_SYMLINKED,
+                .flags = CFTYPE_NOT_ON_ROOT,
                 .seq_show = bfq_io_show_weight,
                 .write_u64 = bfq_io_set_weight_legacy,
         },
@@ -1167,8 +1166,7 @@ struct cftype bfq_blkcg_legacy_files[] = {
 struct cftype bfq_blkg_files[] = {
         {
                 .name = "bfq.weight",
-                .link_name = "weight",
-                .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_SYMLINKED,
+                .flags = CFTYPE_NOT_ON_ROOT,
                 .seq_show = bfq_io_show_weight,
                 .write = bfq_io_set_weight,
         },
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index d71b079bb021..11e215d7937e 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -106,8 +106,6 @@ enum {
         CFTYPE_WORLD_WRITABLE   = (1 << 4),     /* (DON'T USE FOR NEW FILES) S_IWUGO */
         CFTYPE_DEBUG            = (1 << 5),     /* create when cgroup_debug */
 
-        CFTYPE_SYMLINKED        = (1 << 6),     /* 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 */
@@ -545,7 +543,6 @@ 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 155048b0eca2..426a0026225c 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_fill_name(struct cgroup *cgrp, const struct cftype *cft,
-                              char *buf, bool write_link_name)
+static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
+                              char *buf)
 {
         struct cgroup_subsys *ss = cft->ss;
 
@@ -1471,26 +1471,13 @@ static char *cgroup_fill_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,
-                         write_link_name ? cft->link_name : cft->name);
+                         cft->name);
         } else {
-                strscpy(buf, write_link_name ? cft->link_name : cft->name,
-                        CGROUP_FILE_NAME_MAX);
+                strscpy(buf, 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
@@ -1649,9 +1636,6 @@ 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));
 }
 
 /**
@@ -3837,7 +3821,6 @@ 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;
 
@@ -3868,14 +3851,6 @@ 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;
 }