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Date: Mon, 26 Jan 2015 15:58:22 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Al Viro <viro@...IV.linux.org.uk>
Cc: linux-kernel@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Ingo Molnar <mingo@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 00/16 v3] tracing: Add new file system tracefs
On Mon, 26 Jan 2015 15:44:19 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:
> Now what I could also do is to only allow this to be called once. And
> in that case, we can hard code what mkdir and rmdir are. This could
> work as currently there only exists a single instance of the instances
> directory.
>
> I might just do that too.
And just did:
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index c7eb4c58579e..13e17bf677f4 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -50,6 +50,11 @@ static const struct file_operations tracefs_file_operations = {
.llseek = noop_llseek,
};
+struct tracefs_dir_ops {
+ int (*mkdir)(const char *name);
+ int (*rmdir)(const char *name);
+};
+
static char *get_dname(struct dentry *dentry)
{
const char *dname;
@@ -67,13 +72,10 @@ static char *get_dname(struct dentry *dentry)
static int tracefs_syscall_mkdir(struct inode *inode, struct dentry *dentry, umode_t mode)
{
- const struct tracefs_dir_ops *ops = inode ? inode->i_private : NULL;
+ const struct tracefs_dir_ops *ops = inode->i_private;
char *name;
int ret;
- if (!ops)
- return -EPERM;
-
name = get_dname(dentry);
if (!name)
return -ENOMEM;
@@ -98,9 +100,6 @@ static int tracefs_syscall_rmdir(struct inode *inode, struct dentry *dentry)
char *name;
int ret;
- if (!ops)
- return -EPERM;
-
name = get_dname(dentry);
if (!name)
return -ENOMEM;
@@ -317,16 +316,6 @@ static struct file_system_type trace_fs_type = {
};
MODULE_ALIAS_FS("tracefs");
-void tracefs_add_dir_ops(struct dentry *dentry, const struct tracefs_dir_ops *ops)
-{
- struct inode *inode = dentry->d_inode;
-
- if (!inode)
- return;
-
- inode->i_private = (void *)ops;
-}
-
static struct dentry *start_creating(const char *name, struct dentry *parent)
{
struct dentry *dentry;
@@ -425,6 +414,31 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
return end_creating(dentry);
}
+static struct dentry *__create_dir(const char *name, struct dentry *parent,
+ const struct inode_operations *ops)
+{
+ struct dentry *dentry = start_creating(name, parent);
+ struct inode *inode;
+
+ if (IS_ERR(dentry))
+ return NULL;
+
+ inode = tracefs_get_inode(dentry->d_sb);
+ if (unlikely(!inode))
+ return failed_creating(dentry);
+
+ inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
+ inode->i_op = ops;
+ inode->i_fop = &simple_dir_operations;
+
+ /* directory inodes start off with i_nlink == 2 (for "." entry) */
+ inc_nlink(inode);
+ d_instantiate(dentry, inode);
+ inc_nlink(dentry->d_parent->d_inode);
+ fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
+ return end_creating(dentry);
+}
+
/**
* tracefs_create_dir - create a directory in the tracefs filesystem
* @name: a pointer to a string containing the name of the directory to
@@ -444,26 +458,30 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
*/
struct dentry *tracefs_create_dir(const char *name, struct dentry *parent)
{
- struct dentry *dentry = start_creating(name, parent);
- struct inode *inode;
+ return __create_dir(name, parent, &simple_dir_inode_operations);
+}
- if (IS_ERR(dentry))
+struct dentry *tracefs_create_instance_dir(const char *name, struct dentry *parent,
+ int (*mkdir)(const char *name),
+ int (*rmdir)(const char *name))
+{
+ struct tracefs_dir_ops *dir_ops;
+ struct dentry *dentry;
+
+ dir_ops = kmalloc(sizeof(*dir_ops), GFP_KERNEL);
+ if (!dir_ops)
return NULL;
- inode = tracefs_get_inode(dentry->d_sb);
- if (unlikely(!inode))
- return failed_creating(dentry);
+ dir_ops->mkdir = mkdir;
+ dir_ops->rmdir = mkdir;
- inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
- inode->i_op = &tracefs_dir_inode_operations;
- inode->i_fop = &simple_dir_operations;
+ dentry = __create_dir(name, parent, &tracefs_dir_inode_operations);
+ if (!dentry)
+ return NULL;
- /* directory inodes start off with i_nlink == 2 (for "." entry) */
- inc_nlink(inode);
- d_instantiate(dentry, inode);
- inc_nlink(dentry->d_parent->d_inode);
- fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
- return end_creating(dentry);
+ dentry->d_inode->i_private = (void *)dir_ops;
+
+ return dentry;
}
static inline int tracefs_positive(struct dentry *dentry)
diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h
index d142b1f9d453..5b727a17beee 100644
--- a/include/linux/tracefs.h
+++ b/include/linux/tracefs.h
@@ -34,12 +34,9 @@ struct dentry *tracefs_create_dir(const char *name, struct dentry *parent);
void tracefs_remove(struct dentry *dentry);
void tracefs_remove_recursive(struct dentry *dentry);
-struct tracefs_dir_ops {
- int (*mkdir)(const char *name);
- int (*rmdir)(const char *name);
-};
-
-void tracefs_add_dir_ops(struct dentry *dentry, const struct tracefs_dir_ops *ops);
+struct dentry *tracefs_create_instance_dir(const char *name, struct dentry *parent,
+ int (*mkdir)(const char *name),
+ int (*rmdir)(const char *name));
bool tracefs_initialized(void);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c555027c8aaf..2047501dcd16 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6445,18 +6445,13 @@ static int instance_rmdir(const char *name)
return ret;
}
-static const struct tracefs_dir_ops instance_dir_ops = {
- .mkdir = instance_mkdir,
- .rmdir = instance_rmdir,
-};
-
static __init void create_trace_instances(struct dentry *d_tracer)
{
- trace_instance_dir = tracefs_create_dir("instances", d_tracer);
+ trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer,
+ instance_mkdir,
+ instance_rmdir);
if (WARN_ON(!trace_instance_dir))
return;
-
- tracefs_add_dir_ops(trace_instance_dir, &instance_dir_ops);
}
static void
--
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