Some more nits.
Subject: eventfs: Implement functions to create files and dirs when accessed
On Thu, 13 Jul 2023 17:03:20 +0530 Ajay Kaher akaher@vmware.com wrote:
Adding create_file(), create_dir() to create file, dir at runtime when they are accessed.
These function will be called either from lookup of inode_operations or open of file_operations.
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.
Signed-off-by: Ajay Kaher akaher@vmware.com Co-developed-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Tested-by: Ching-lin Yu chinglinyu@google.com
fs/tracefs/event_inode.c | 110 +++++++++++++++++++++++++++++++++++++++ fs/tracefs/inode.c | 47 +++++++++++++++++ include/linux/tracefs.h | 7 +++ 3 files changed, 164 insertions(+)
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 322a77be5a56..34b5d3d8005b 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -46,6 +46,116 @@ struct eventfs_file { static DEFINE_MUTEX(eventfs_mutex); DEFINE_STATIC_SRCU(eventfs_srcu); +/**
- create_file - create a file in the tracefs filesystem
- @name: the name of the file to create.
- @mode: the permission that the file should have.
- @parent: parent dentry for this file.
- @data: something that the caller will want to get to later on.
The inode.i_private pointer will point to this value on
the open() call.
Again, should move the extra lines into the description.
- @fop: struct file_operations that should be used for this file.
- This is the basic "create a file" function for tracefs. It allows for a
- wide range of flexibility in creating a file.
- This function will return a pointer to a dentry if it succeeds. This
- pointer must be passed to the tracefs_remove() function when the file 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 tracefs is not enabled in the kernel, the value -%ENODEV will be
- returned.
- */
+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);
+}
+/**
- create_dir - create a dir in the tracefs filesystem
- @name: the name of the file to create.
- @mode: the permission that the file should have.
- @parent: parent dentry for this file.
- @data: something that the caller will want to get to later on.
The inode.i_private pointer will point to this value on
the open() call.
Move the extra lines down into the description here too.
- @fop: struct file_operations that should be used for this dir.
- @iop: struct inode_operations that should be used for this dir.
- This is the basic "create a dir" function for eventfs. It allows for a
- wide range of flexibility in creating a dir.
- This function will return a pointer to a dentry if it succeeds. This
- pointer must be passed to the tracefs_remove() function when the file 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 tracefs is not enabled in the kernel, the value -%ENODEV will be
- returned.
- */
+struct dentry *create_dir(const char *name, umode_t mode,
struct dentry *parent, void *data,const struct file_operations *fop,const struct inode_operations *iop)+{
- struct tracefs_inode *ti;
- struct dentry *dentry;
- struct inode *inode;
- WARN_ON(!S_ISDIR(mode));
- 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_op = iop;
- inode->i_fop = fop;
- 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);
+} static const struct file_operations eventfs_file_operations = { }; diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 7ef3a02766f5..7dc692a5fee1 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -451,6 +451,53 @@ struct dentry *tracefs_end_creating(struct dentry *dentry) return dentry; }
This needs to be documented. What about:
/** * 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;
+}
-- Steve
/**
- tracefs_create_file - create a file in the tracefs filesystem
- @name: a pointer to a string containing the name of the file to
create. diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h index 2c08edd4a739..47c1b4d21735 100644 --- a/include/linux/tracefs.h +++ b/include/linux/tracefs.h @@ -23,6 +23,13 @@ struct file_operations; struct eventfs_file; +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);
struct dentry *eventfs_create_events_dir(const char *name, struct dentry *parent);