[PATCH 06/10] debugfs: implement symbolic links
From: Peter Oberparleiter <[EMAIL PROTECTED]>
debugfs: implement symbolic links
Implement a new function debugfs_create_symlink() which can be used
to create symbolic links in debugfs. This function can be useful
for people moving functionality from /proc to debugfs (e.g. the
gcov-kernel patch).
Signed-off-by: Peter Oberparleiter <[EMAIL PROTECTED]>
Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
---
fs/debugfs/file.c | 12 +++
fs/debugfs/inode.c | 76 --
include/linux/debugfs.h | 10 ++
3 files changed, 94 insertions(+), 4 deletions(-)
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 8d130cc..682f928 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -16,6 +16,7 @@
#include
#include
#include
+#include
#include
static ssize_t default_read_file(struct file *file, char __user *buf,
@@ -44,6 +45,17 @@ const struct file_operations debugfs_file_operations = {
.open = default_open,
};
+static void *debugfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ nd_set_link(nd, dentry->d_inode->i_private);
+ return NULL;
+}
+
+const struct inode_operations debugfs_link_operations = {
+ .readlink = generic_readlink,
+ .follow_link= debugfs_follow_link,
+};
+
static void debugfs_u8_set(void *data, u64 val)
{
*(u8 *)data = val;
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index c692487..9c51a9f 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -25,11 +25,13 @@
#include
#include
#include
+#include
#define DEBUGFS_MAGIC 0x64626720
/* declared over in file.c */
extern struct file_operations debugfs_file_operations;
+extern struct inode_operations debugfs_link_operations;
static struct vfsmount *debugfs_mount;
static int debugfs_mount_count;
@@ -51,6 +53,9 @@ static struct inode *debugfs_get_inode(struct super_block
*sb, int mode, dev_t d
case S_IFREG:
inode->i_fop = _file_operations;
break;
+ case S_IFLNK:
+ inode->i_op = _link_operations;
+ break;
case S_IFDIR:
inode->i_op = _dir_inode_operations;
inode->i_fop = _dir_operations;
@@ -96,6 +101,12 @@ static int debugfs_mkdir(struct inode *dir, struct dentry
*dentry, int mode)
return res;
}
+static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode)
+{
+ mode = (mode & S_IALLUGO) | S_IFLNK;
+ return debugfs_mknod(dir, dentry, mode, 0);
+}
+
static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode)
{
int res;
@@ -158,10 +169,17 @@ static int debugfs_create_by_name(const char *name,
mode_t mode,
mutex_lock(>d_inode->i_mutex);
*dentry = lookup_one_len(name, parent, strlen(name));
if (!IS_ERR(*dentry)) {
- if ((mode & S_IFMT) == S_IFDIR)
+ switch (mode & S_IFMT) {
+ case S_IFDIR:
error = debugfs_mkdir(parent->d_inode, *dentry, mode);
- else
+ break;
+ case S_IFLNK:
+ error = debugfs_link(parent->d_inode, *dentry, mode);
+ break;
+ default:
error = debugfs_create(parent->d_inode, *dentry, mode);
+ break;
+ }
dput(*dentry);
} else
error = PTR_ERR(*dentry);
@@ -259,6 +277,49 @@ struct dentry *debugfs_create_dir(const char *name, struct
dentry *parent)
EXPORT_SYMBOL_GPL(debugfs_create_dir);
/**
+ * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
+ * @name: a pointer to a string containing the name of the symbolic link to
+ *create.
+ * @parent: a pointer to the parent dentry for this symbolic link. This
+ * should be a directory dentry if set. If this paramater is NULL,
+ * then the symbolic link will be created in the root of the debugfs
+ * filesystem.
+ * @target: a pointer to a string containing the path to the target of the
+ * symbolic link.
+ *
+ * This function creates a symbolic link with the given name in debugfs that
+ * links to the given target path.
+ *
+ * This function will return a pointer to a dentry if it succeeds. This
+ * pointer must be passed to the debugfs_remove() function when the symbolic
+ * link is to be removed (no automatic cleanup happens if your module is
+ * unloaded, you are responsible here.) If an error occurs, %NULL will be
+ * returned.
+ *
+ * If debugfs is not enabled in the kernel, the value -%ENODEV will be
+ * returned. It is not wise to check for this value, but rather, check for
+ * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
+ * code.
+ */
+struct dentry
[PATCH 06/10] debugfs: implement symbolic links
From: Peter Oberparleiter [EMAIL PROTECTED]
debugfs: implement symbolic links
Implement a new function debugfs_create_symlink() which can be used
to create symbolic links in debugfs. This function can be useful
for people moving functionality from /proc to debugfs (e.g. the
gcov-kernel patch).
Signed-off-by: Peter Oberparleiter [EMAIL PROTECTED]
Signed-off-by: Greg Kroah-Hartman [EMAIL PROTECTED]
---
fs/debugfs/file.c | 12 +++
fs/debugfs/inode.c | 76 --
include/linux/debugfs.h | 10 ++
3 files changed, 94 insertions(+), 4 deletions(-)
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 8d130cc..682f928 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -16,6 +16,7 @@
#include linux/module.h
#include linux/fs.h
#include linux/pagemap.h
+#include linux/namei.h
#include linux/debugfs.h
static ssize_t default_read_file(struct file *file, char __user *buf,
@@ -44,6 +45,17 @@ const struct file_operations debugfs_file_operations = {
.open = default_open,
};
+static void *debugfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ nd_set_link(nd, dentry-d_inode-i_private);
+ return NULL;
+}
+
+const struct inode_operations debugfs_link_operations = {
+ .readlink = generic_readlink,
+ .follow_link= debugfs_follow_link,
+};
+
static void debugfs_u8_set(void *data, u64 val)
{
*(u8 *)data = val;
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index c692487..9c51a9f 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -25,11 +25,13 @@
#include linux/namei.h
#include linux/debugfs.h
#include linux/fsnotify.h
+#include linux/string.h
#define DEBUGFS_MAGIC 0x64626720
/* declared over in file.c */
extern struct file_operations debugfs_file_operations;
+extern struct inode_operations debugfs_link_operations;
static struct vfsmount *debugfs_mount;
static int debugfs_mount_count;
@@ -51,6 +53,9 @@ static struct inode *debugfs_get_inode(struct super_block
*sb, int mode, dev_t d
case S_IFREG:
inode-i_fop = debugfs_file_operations;
break;
+ case S_IFLNK:
+ inode-i_op = debugfs_link_operations;
+ break;
case S_IFDIR:
inode-i_op = simple_dir_inode_operations;
inode-i_fop = simple_dir_operations;
@@ -96,6 +101,12 @@ static int debugfs_mkdir(struct inode *dir, struct dentry
*dentry, int mode)
return res;
}
+static int debugfs_link(struct inode *dir, struct dentry *dentry, int mode)
+{
+ mode = (mode S_IALLUGO) | S_IFLNK;
+ return debugfs_mknod(dir, dentry, mode, 0);
+}
+
static int debugfs_create(struct inode *dir, struct dentry *dentry, int mode)
{
int res;
@@ -158,10 +169,17 @@ static int debugfs_create_by_name(const char *name,
mode_t mode,
mutex_lock(parent-d_inode-i_mutex);
*dentry = lookup_one_len(name, parent, strlen(name));
if (!IS_ERR(*dentry)) {
- if ((mode S_IFMT) == S_IFDIR)
+ switch (mode S_IFMT) {
+ case S_IFDIR:
error = debugfs_mkdir(parent-d_inode, *dentry, mode);
- else
+ break;
+ case S_IFLNK:
+ error = debugfs_link(parent-d_inode, *dentry, mode);
+ break;
+ default:
error = debugfs_create(parent-d_inode, *dentry, mode);
+ break;
+ }
dput(*dentry);
} else
error = PTR_ERR(*dentry);
@@ -259,6 +277,49 @@ struct dentry *debugfs_create_dir(const char *name, struct
dentry *parent)
EXPORT_SYMBOL_GPL(debugfs_create_dir);
/**
+ * debugfs_create_symlink- create a symbolic link in the debugfs filesystem
+ * @name: a pointer to a string containing the name of the symbolic link to
+ *create.
+ * @parent: a pointer to the parent dentry for this symbolic link. This
+ * should be a directory dentry if set. If this paramater is NULL,
+ * then the symbolic link will be created in the root of the debugfs
+ * filesystem.
+ * @target: a pointer to a string containing the path to the target of the
+ * symbolic link.
+ *
+ * This function creates a symbolic link with the given name in debugfs that
+ * links to the given target path.
+ *
+ * This function will return a pointer to a dentry if it succeeds. This
+ * pointer must be passed to the debugfs_remove() function when the symbolic
+ * link is to be removed (no automatic cleanup happens if your module is
+ * unloaded, you are responsible here.) If an error occurs, %NULL will be
+ * returned.
+ *
+ * If debugfs is not enabled in the kernel, the value -%ENODEV will be
+ * returned. It is not wise to check for this value, but
