Adding eventfs_create_file(), eventfs_create_dir() to create file, dir at runtime as and when requires.
These function will be called either from lookup of inode_operations or open 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 | 125 +++++++++++++++++++++++++++++++++++++++ fs/tracefs/inode.c | 47 +++++++++++++++ include/linux/tracefs.h | 6 ++ 3 files changed, 178 insertions(+)
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 9ab675edf..0ee27f7c8 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -83,6 +83,131 @@ static void eventfs_up_write(struct rw_semaphore *eventfs_rwsem) up_write(eventfs_rwsem); }
+/** + * eventfs_create_file - create a file in the tracefs filesystem + * @name: a pointer to a string containing the name of the file to create. + * @mode: the permission that the file should have. + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is NULL, then the + * file will be created in the root of the tracefs filesystem. + * @data: a pointer to 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. + * @fop: a pointer to a 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. + */ +static struct dentry *eventfs_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 (security_locked_down(LOCKDOWN_TRACEFS)) + return NULL; + + 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); +} + +/** + * eventfs_create_dir - create a dir in the tracefs filesystem + * @name: a pointer to a string containing the name of the file to create. + * @mode: the permission that the file should have. + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is NULL, then the + * file will be created in the root of the tracefs filesystem. + * @data: a pointer to 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. + * @fop: a pointer to a struct file_operations that should be used for + * this dir. + * @iop: a pointer to a 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. + */ +static struct dentry *eventfs_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; + + if (security_locked_down(LOCKDOWN_TRACEFS)) + return NULL; + + 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 7df1752e8..66c4df734 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -452,6 +452,53 @@ struct dentry *tracefs_end_creating(struct dentry *dentry) return dentry; }
+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; +} + +struct dentry *eventfs_failed_creating(struct dentry *dentry) +{ + dput(dentry); + simple_release_fs(&tracefs_mount, &tracefs_mount_count); + return NULL; +} + +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. diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h index ea10ccc87..57bfd1322 100644 --- a/include/linux/tracefs.h +++ b/include/linux/tracefs.h @@ -38,6 +38,12 @@ struct eventfs_file { bool created; };
+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, struct rw_semaphore *eventfs_rwsem);