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 | 61 +++++++++++++++++++++++++++++++-- fs/tracefs/inode.c | 74 ++++++++++++++++++++++++++++++++++++++++ fs/tracefs/internal.h | 3 ++ 3 files changed, 136 insertions(+), 2 deletions(-)
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 24d645c61029..5240bd2c81e7 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -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) { - return NULL; + 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) diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 4acc4b4dfd22..d9273066f25f 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -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. diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h index 9bfad9d95a4a..69c2b1d87c46 100644 --- a/fs/tracefs/internal.h +++ b/fs/tracefs/internal.h @@ -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 */