[PATCH 2/2] kernfs: Allow creation with external gen + ino numbers

From: Namhyung Kim
Date: Wed Oct 16 2019 - 08:50:42 EST

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In reply to: Namhyung Kim: "[PATCH 1/2] cgroup: Add generation number with cgroup id"
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Extend file and directory creation API to take external generation
number and inode number. Passing 0 as inode number will keep original
behavior.

The cgroup id will be used as inode number from now on so allocate id
for each file as well.

Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 4 +-
fs/kernfs/dir.c | 63 ++++++++++++++++++++------
fs/kernfs/file.c | 9 ++--
fs/kernfs/kernfs-internal.h | 5 ++
fs/sysfs/file.c | 2 +-
include/linux/kernfs.h | 25 +++++++---
kernel/cgroup/cgroup.c | 12 ++++-
7 files changed, 90 insertions(+), 30 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index a46dee8e78db..a2fbcab3189e 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -206,7 +206,7 @@ static int rdtgroup_add_file(struct kernfs_node *parent_kn, struct rftype *rft)

kn = __kernfs_create_file(parent_kn, rft->name, rft->mode,
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
- 0, rft->kf_ops, rft, NULL, NULL);
+ 0, rft->kf_ops, rft, NULL, NULL, 0, 0);
if (IS_ERR(kn))
return PTR_ERR(kn);

@@ -2294,7 +2294,7 @@ static int mon_addfile(struct kernfs_node *parent_kn, const char *name,

kn = __kernfs_create_file(parent_kn, name, 0444,
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, 0,
- &kf_mondata_ops, priv, NULL, NULL);
+ &kf_mondata_ops, priv, NULL, NULL, 0, 0);
if (IS_ERR(kn))
return PTR_ERR(kn);

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 6ebae6bbe6a5..f2e54532c110 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -618,10 +618,10 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
struct kernfs_node *parent,
const char *name, umode_t mode,
kuid_t uid, kgid_t gid,
+ u32 gen, int ino,
unsigned flags)
{
struct kernfs_node *kn;
- u32 gen;
int cursor;
int ret;

@@ -635,11 +635,24 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,

idr_preload(GFP_KERNEL);
spin_lock(&kernfs_idr_lock);
- cursor = idr_get_cursor(&root->ino_idr);
- ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC);
- if (ret >= 0 && ret < cursor)
- root->next_generation++;
- gen = root->next_generation;
+
+ if (ino == 0) {
+ cursor = idr_get_cursor(&root->ino_idr);
+ ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC);
+ if (ret >= 0 && ret < cursor)
+ root->next_generation++;
+ gen = root->next_generation;
+ } else {
+ ret = idr_alloc(&root->ino_idr, kn, ino, ino + 1, GFP_ATOMIC);
+ if (ret != ino) {
+ WARN_ONCE(1, "kernfs ino was used: %d", ino);
+ ret = -EINVAL;
+ } else {
+ WARN_ON(root->next_generation > gen);
+ root->next_generation = gen;
+ }
+ }
+
spin_unlock(&kernfs_idr_lock);
idr_preload_end();
if (ret < 0)
@@ -696,7 +709,24 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
struct kernfs_node *kn;

kn = __kernfs_new_node(kernfs_root(parent), parent,
- name, mode, uid, gid, flags);
+ name, mode, uid, gid, 0, 0, flags);
+ if (kn) {
+ kernfs_get(parent);
+ kn->parent = parent;
+ }
+ return kn;
+}
+
+struct kernfs_node *kernfs_new_node_with_id(struct kernfs_node *parent,
+ const char *name, umode_t mode,
+ kuid_t uid, kgid_t gid,
+ u32 gen, int ino,
+ unsigned flags)
+{
+ struct kernfs_node *kn;
+
+ kn = __kernfs_new_node(kernfs_root(parent), parent,
+ name, mode, uid, gid, gen, ino, flags);
if (kn) {
kernfs_get(parent);
kn->parent = parent;
@@ -965,7 +995,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
root->next_generation = 1;

kn = __kernfs_new_node(root, NULL, "", S_IFDIR | S_IRUGO | S_IXUGO,
- GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
+ GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, 0, 0,
KERNFS_DIR);
if (!kn) {
idr_destroy(&root->ino_idr);
@@ -1000,7 +1030,7 @@ void kernfs_destroy_root(struct kernfs_root *root)
}

/**
- * kernfs_create_dir_ns - create a directory
+ * __kernfs_create_dir - create a directory
* @parent: parent in which to create a new directory
* @name: name of the new directory
* @mode: mode of the new directory
@@ -1008,20 +1038,23 @@ void kernfs_destroy_root(struct kernfs_root *root)
* @gid: gid of the new directory
* @priv: opaque data associated with the new directory
* @ns: optional namespace tag of the directory
+ * @gen: optional inode generation number
+ * @ino: optional inode number
*
* Returns the created node on success, ERR_PTR() value on failure.
*/
-struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
- const char *name, umode_t mode,
- kuid_t uid, kgid_t gid,
- void *priv, const void *ns)
+struct kernfs_node *__kernfs_create_dir(struct kernfs_node *parent,
+ const char *name, umode_t mode,
+ kuid_t uid, kgid_t gid,
+ void *priv, const void *ns,
+ u32 gen, int ino)
{
struct kernfs_node *kn;
int rc;

/* allocate */
- kn = kernfs_new_node(parent, name, mode | S_IFDIR,
- uid, gid, KERNFS_DIR);
+ kn = kernfs_new_node_with_id(parent, name, mode | S_IFDIR,
+ uid, gid, gen, ino, KERNFS_DIR);
if (!kn)
return ERR_PTR(-ENOMEM);

diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index e8c792b49616..8280b750b733 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -981,6 +981,8 @@ const struct file_operations kernfs_file_fops = {
* @priv: private data for the file
* @ns: optional namespace tag of the file
* @key: lockdep key for the file's active_ref, %NULL to disable lockdep
+ * @gen: optional inode generation number
+ * @ino: optional inode number
*
* Returns the created node on success, ERR_PTR() value on error.
*/
@@ -990,7 +992,8 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
loff_t size,
const struct kernfs_ops *ops,
void *priv, const void *ns,
- struct lock_class_key *key)
+ struct lock_class_key *key,
+ u32 gen, int ino)
{
struct kernfs_node *kn;
unsigned flags;
@@ -998,8 +1001,8 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,

flags = KERNFS_FILE;

- kn = kernfs_new_node(parent, name, (mode & S_IALLUGO) | S_IFREG,
- uid, gid, flags);
+ kn = kernfs_new_node_with_id(parent, name, (mode & S_IALLUGO) | S_IFREG,
+ uid, gid, gen, ino, flags);
if (!kn)
return ERR_PTR(-ENOMEM);

diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 02ce570a9a3c..42c787720a1f 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -109,6 +109,11 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
const char *name, umode_t mode,
kuid_t uid, kgid_t gid,
unsigned flags);
+struct kernfs_node *kernfs_new_node_with_id(struct kernfs_node *parent,
+ const char *name, umode_t mode,
+ kuid_t uid, kgid_t gid,
+ u32 gen, int ino,
+ unsigned flags);
struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root,
unsigned int ino);

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 130fc6fbcc03..a21aa1aa2106 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -303,7 +303,7 @@ int sysfs_add_file_mode_ns(struct kernfs_node *parent,
#endif

kn = __kernfs_create_file(parent, attr->name, mode & 0777, uid, gid,
- size, ops, (void *)attr, ns, key);
+ size, ops, (void *)attr, ns, key, 0, 0);
if (IS_ERR(kn)) {
if (PTR_ERR(kn) == -EEXIST)
sysfs_warn_dup(parent, attr->name);
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 936b61bd504e..3764a870a279 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -340,10 +340,11 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
unsigned int flags, void *priv);
void kernfs_destroy_root(struct kernfs_root *root);

-struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
+struct kernfs_node *__kernfs_create_dir(struct kernfs_node *parent,
const char *name, umode_t mode,
kuid_t uid, kgid_t gid,
- void *priv, const void *ns);
+ void *priv, const void *ns,
+ u32 gen, int ino);
struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
const char *name);
struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
@@ -352,7 +353,8 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
loff_t size,
const struct kernfs_ops *ops,
void *priv, const void *ns,
- struct lock_class_key *key);
+ struct lock_class_key *key,
+ u32 gen, int ino);
struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
const char *name,
struct kernfs_node *target);
@@ -438,16 +440,17 @@ kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags,
static inline void kernfs_destroy_root(struct kernfs_root *root) { }

static inline struct kernfs_node *
-kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
+__kernfs_create_dir(struct kernfs_node *parent, const char *name,
umode_t mode, kuid_t uid, kgid_t gid,
- void *priv, const void *ns)
+ void *priv, const void *ns, u32 gen, int ino)
{ return ERR_PTR(-ENOSYS); }

static inline struct kernfs_node *
__kernfs_create_file(struct kernfs_node *parent, const char *name,
umode_t mode, kuid_t uid, kgid_t gid,
loff_t size, const struct kernfs_ops *ops,
- void *priv, const void *ns, struct lock_class_key *key)
+ void *priv, const void *ns, struct lock_class_key *key,
+ u32 gen, int ino)
{ return ERR_PTR(-ENOSYS); }

static inline struct kernfs_node *
@@ -528,6 +531,14 @@ kernfs_walk_and_get(struct kernfs_node *kn, const char *path)
return kernfs_walk_and_get_ns(kn, path, NULL);
}

+static inline struct kernfs_node *
+kernfs_create_dir_ns(struct kernfs_node *parent, const char *name, umode_t mode,
+ kuid_t uid, kgid_t gid, void *priv, const void *ns)
+{
+ return __kernfs_create_dir(parent, name, mode,
+ uid, gid, priv, ns, 0, 0);
+}
+
static inline struct kernfs_node *
kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
void *priv)
@@ -549,7 +560,7 @@ kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
key = (struct lock_class_key *)&ops->lockdep_key;
#endif
return __kernfs_create_file(parent, name, mode, uid, gid,
- size, ops, priv, ns, key);
+ size, ops, priv, ns, key, 0, 0);
}

static inline struct kernfs_node *
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 44c67d26c1fe..13d0d181a9f8 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -3916,16 +3916,22 @@ static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
char name[CGROUP_FILE_NAME_MAX];
struct kernfs_node *kn;
struct lock_class_key *key = NULL;
+ struct cgroup_root *root = cgrp->root;
+ int ino, gen;
int ret;

#ifdef CONFIG_DEBUG_LOCK_ALLOC
key = &cft->lockdep_key;
#endif
+
+ ino = cgroup_idr_alloc(&root->cgroup_idr, NULL, false, GFP_KERNEL);
+ gen = root->cgroup_idr.generation;
+
kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
cgroup_file_mode(cft),
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
0, cft->kf_ops, cft,
- NULL, key);
+ NULL, key, gen, ino);
if (IS_ERR(kn))
return PTR_ERR(kn);

@@ -5426,7 +5432,9 @@ int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
}

/* create the directory */
- kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
+ kn = __kernfs_create_dir(parent->kn, name, mode,
+ GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
+ cgrp, NULL, cgrp->gen, cgrp->id);
if (IS_ERR(kn)) {
ret = PTR_ERR(kn);
goto out_destroy;
--
2.23.0.700.g56cf767bdb-goog

Next message: David Hildenbrand: "Re: [PATCH RFC v3 6/9] mm: Allow to offline PageOffline() pages with a reference count of 0"
Previous message: Luis Chamberlain: "Re: Module loading problem since 5.3"
In reply to: Namhyung Kim: "[PATCH 1/2] cgroup: Add generation number with cgroup id"
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