From 7c8d469877b16d2c1cecf101a0abb7b218db85bc Mon Sep 17 00:00:00 2001 From: Nicolai Stange Date: Tue, 31 Oct 2017 00:15:47 +0100 Subject: 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 Signed-off-by: Greg Kroah-Hartman --- fs/debugfs/inode.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-) (limited to 'fs/debugfs/inode.c') diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index c59f015f386e..a9c3d3e9af39 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); -- cgit