Commit a3760079 authored by Ajay Kaher's avatar Ajay Kaher Committed by Steven Rostedt (Google)
Browse files

eventfs: Implement functions to create files and dirs when accessed 

Add create_file() and create_dir() functions to create the files and
directories respectively when they are accessed. The functions will be
called from the lookup operation of the inode_operations or from the open
function of file_operations.

Link: https://lkml.kernel.org/r/1690568452-46553-8-git-send-email-akaher@vmware.com



Signed-off-by: default avatarAjay Kaher <akaher@vmware.com>
Co-developed-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: default avatarChing-lin Yu <chinglinyu@google.com>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 63940449

fs/tracefs/event_inode.c

+59 −2
Original line number Diff line number Diff line
@@ -101,7 +101,34 @@ static struct dentry *create_file(const char *name, umode_t mode, 
				  struct dentry *parent, void *data,

				  const struct file_operations *fop)

{

	struct tracefs_inode *ti;

	struct dentry *dentry;

	struct inode *inode;



	if (!(mode & S_IFMT))

		mode |= S_IFREG;



	if (WARN_ON_ONCE(!S_ISREG(mode)))

		return NULL;



	dentry = eventfs_start_creating(name, parent);



	if (IS_ERR(dentry))

		return dentry;



	inode = tracefs_get_inode(dentry->d_sb);

	if (unlikely(!inode))

		return eventfs_failed_creating(dentry);



	inode->i_mode = mode;

	inode->i_fop = fop;

	inode->i_private = data;



	ti = get_tracefs(inode);

	ti->flags |= TRACEFS_EVENT_INODE;

	d_instantiate(dentry, inode);

	fsnotify_create(dentry->d_parent->d_inode, dentry);

	return eventfs_end_creating(dentry);

};



/**
@@ -123,7 +150,31 @@ static struct dentry *create_file(const char *name, umode_t mode, 
 */

static struct dentry *create_dir(const char *name, struct dentry *parent, void *data)

{

	return NULL;

	struct tracefs_inode *ti;

	struct dentry *dentry;

	struct inode *inode;



	dentry = eventfs_start_creating(name, parent);

	if (IS_ERR(dentry))

		return dentry;



	inode = tracefs_get_inode(dentry->d_sb);

	if (unlikely(!inode))

		return eventfs_failed_creating(dentry);



	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;

	inode->i_op = &eventfs_root_dir_inode_operations;

	inode->i_fop = &eventfs_file_operations;

	inode->i_private = data;



	ti = get_tracefs(inode);

	ti->flags |= TRACEFS_EVENT_INODE;



	inc_nlink(inode);

	d_instantiate(dentry, inode);

	inc_nlink(dentry->d_parent->d_inode);

	fsnotify_mkdir(dentry->d_parent->d_inode, dentry);

	return eventfs_end_creating(dentry);

}



/**
@@ -234,6 +285,12 @@ create_dentry(struct eventfs_file *ef, struct dentry *parent, bool lookup) 
	} else {

		/* A race here, should try again (unless freed) */

		invalidate = true;



		/*

		 * Should never happen unless we get here due to being freed.

		 * Otherwise it means two dentries exist with the same name.

		 */

		WARN_ON_ONCE(!ef->is_freed);

	}

	mutex_unlock(&eventfs_mutex);

	if (invalidate)

fs/tracefs/inode.c

+74 −0
Original line number Diff line number Diff line
@@ -474,6 +474,80 @@ struct dentry *tracefs_end_creating(struct dentry *dentry) 
	return dentry;

}



/**

 * eventfs_start_creating - start the process of creating a dentry

 * @name: Name of the file created for the dentry

 * @parent: The parent dentry where this dentry will be created

 *

 * This is a simple helper function for the dynamically created eventfs

 * files. When the directory of the eventfs files are accessed, their

 * dentries are created on the fly. This function is used to start that

 * process.

 */

struct dentry *eventfs_start_creating(const char *name, struct dentry *parent)

{

	struct dentry *dentry;

	int error;



	error = simple_pin_fs(&trace_fs_type, &tracefs_mount,

			      &tracefs_mount_count);

	if (error)

		return ERR_PTR(error);



	/*

	 * If the parent is not specified, we create it in the root.

	 * We need the root dentry to do this, which is in the super

	 * block. A pointer to that is in the struct vfsmount that we

	 * have around.

	 */

	if (!parent)

		parent = tracefs_mount->mnt_root;



	if (unlikely(IS_DEADDIR(parent->d_inode)))

		dentry = ERR_PTR(-ENOENT);

	else

		dentry = lookup_one_len(name, parent, strlen(name));



	if (!IS_ERR(dentry) && dentry->d_inode) {

		dput(dentry);

		dentry = ERR_PTR(-EEXIST);

	}



	if (IS_ERR(dentry))

		simple_release_fs(&tracefs_mount, &tracefs_mount_count);



	return dentry;

}



/**

 * eventfs_failed_creating - clean up a failed eventfs dentry creation

 * @dentry: The dentry to clean up

 *

 * If after calling eventfs_start_creating(), a failure is detected, the

 * resources created by eventfs_start_creating() needs to be cleaned up. In

 * that case, this function should be called to perform that clean up.

 */

struct dentry *eventfs_failed_creating(struct dentry *dentry)

{

	dput(dentry);

	simple_release_fs(&tracefs_mount, &tracefs_mount_count);

	return NULL;

}



/**

 * eventfs_end_creating - Finish the process of creating a eventfs dentry

 * @dentry: The dentry that has successfully been created.

 *

 * This function is currently just a place holder to match

 * eventfs_start_creating(). In case any synchronization needs to be added,

 * this function will be used to implement that without having to modify

 * the callers of eventfs_start_creating().

 */

struct dentry *eventfs_end_creating(struct dentry *dentry)

{

	return dentry;

}



/**

 * tracefs_create_file - create a file in the tracefs filesystem

 * @name: a pointer to a string containing the name of the file to create.

fs/tracefs/internal.h

+3 −0
Original line number Diff line number Diff line
@@ -21,6 +21,9 @@ struct dentry *tracefs_start_creating(const char *name, struct dentry *parent); 
struct dentry *tracefs_end_creating(struct dentry *dentry);

struct dentry *tracefs_failed_creating(struct dentry *dentry);

struct inode *tracefs_get_inode(struct super_block *sb);

struct dentry *eventfs_start_creating(const char *name, struct dentry *parent);

struct dentry *eventfs_failed_creating(struct dentry *dentry);

struct dentry *eventfs_end_creating(struct dentry *dentry);

void eventfs_set_ef_status_free(struct dentry *dentry);



#endif /* _TRACEFS_INTERNAL_H */