debugfs: add support for more elaborate ->d_fsdata
Currently, the user provided fops, "real_fops", are stored directly into
->d_fsdata.
In order to be able to store more per-file state and thus prepare for more
granular file removal protection, wrap the real_fops into a dynamically
allocated container struct, debugfs_fsdata.
A struct debugfs_fsdata gets allocated at file creation and freed from the
newly intoduced ->d_release().
Finally, move the implementation of debugfs_real_fops() out of the public
debugfs header such that struct debugfs_fsdata's declaration can be kept
private.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index c59f015..a9c3d3e 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -185,6 +185,11 @@ static const struct super_operations debugfs_super_operations = {
.evict_inode = debugfs_evict_inode,
};
+static void debugfs_release_dentry(struct dentry *dentry)
+{
+ kfree(dentry->d_fsdata);
+}
+
static struct vfsmount *debugfs_automount(struct path *path)
{
debugfs_automount_t f;
@@ -194,6 +199,7 @@ static struct vfsmount *debugfs_automount(struct path *path)
static const struct dentry_operations debugfs_dops = {
.d_delete = always_delete_dentry,
+ .d_release = debugfs_release_dentry,
.d_automount = debugfs_automount,
};
@@ -341,24 +347,34 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
{
struct dentry *dentry;
struct inode *inode;
+ struct debugfs_fsdata *fsd;
+
+ fsd = kmalloc(sizeof(*fsd), GFP_KERNEL);
+ if (!fsd)
+ return NULL;
if (!(mode & S_IFMT))
mode |= S_IFREG;
BUG_ON(!S_ISREG(mode));
dentry = start_creating(name, parent);
- if (IS_ERR(dentry))
+ if (IS_ERR(dentry)) {
+ kfree(fsd);
return NULL;
+ }
inode = debugfs_get_inode(dentry->d_sb);
- if (unlikely(!inode))
+ if (unlikely(!inode)) {
+ kfree(fsd);
return failed_creating(dentry);
+ }
inode->i_mode = mode;
inode->i_private = data;
inode->i_fop = proxy_fops;
- dentry->d_fsdata = (void *)real_fops;
+ fsd->real_fops = real_fops;
+ dentry->d_fsdata = fsd;
d_instantiate(dentry, inode);
fsnotify_create(d_inode(dentry->d_parent), dentry);
