diff options
| -rw-r--r-- | fs/tracefs/event_inode.c | 143 | ||||
| -rw-r--r-- | include/linux/tracefs.h | 4 |
2 files changed, 147 insertions, 0 deletions
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 5240bd2c81e7..da8d2e73cc47 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -198,6 +198,14 @@ void eventfs_set_ef_status_free(struct dentry *dentry) if (!ef) goto out; + /* + * If ef was freed, then the LSB bit is set for d_fsdata. + * But this should not happen, as it should still have a + * ref count that prevents it. Warn in case it does. + */ + if (WARN_ON_ONCE((unsigned long)ef & 1)) + goto out; + dentry->d_fsdata = NULL; ef->dentry = NULL; out: @@ -656,3 +664,138 @@ int eventfs_add_file(const char *name, umode_t mode, mutex_unlock(&eventfs_mutex); return 0; } + +static void free_ef(struct rcu_head *head) +{ + struct eventfs_file *ef = container_of(head, struct eventfs_file, rcu); + + kfree(ef->name); + kfree(ef->ei); + kfree(ef); +} + +/** + * eventfs_remove_rec - remove eventfs dir or file from list + * @ef: eventfs_file to be removed. + * @head: to create list of eventfs_file to be deleted + * @level: to check recursion depth + * + * The helper function eventfs_remove_rec() is used to clean up and free the + * associated data from eventfs for both of the added functions. + */ +static void eventfs_remove_rec(struct eventfs_file *ef, struct list_head *head, int level) +{ + struct eventfs_file *ef_child; + + if (!ef) + return; + /* + * Check recursion depth. It should never be greater than 3: + * 0 - events/ + * 1 - events/group/ + * 2 - events/group/event/ + * 3 - events/group/event/file + */ + if (WARN_ON_ONCE(level > 3)) + return; + + if (ef->ei) { + /* search for nested folders or files */ + list_for_each_entry_srcu(ef_child, &ef->ei->e_top_files, list, + lockdep_is_held(&eventfs_mutex)) { + eventfs_remove_rec(ef_child, head, level + 1); + } + } + + list_del_rcu(&ef->list); + list_add_tail(&ef->del_list, head); +} + +/** + * eventfs_remove - remove eventfs dir or file from list + * @ef: eventfs_file to be removed. + * + * This function acquire the eventfs_mutex lock and call eventfs_remove_rec() + */ +void eventfs_remove(struct eventfs_file *ef) +{ + struct eventfs_file *tmp; + LIST_HEAD(ef_del_list); + struct dentry *dentry_list = NULL; + struct dentry *dentry; + + if (!ef) + return; + + mutex_lock(&eventfs_mutex); + eventfs_remove_rec(ef, &ef_del_list, 0); + list_for_each_entry_safe(ef, tmp, &ef_del_list, del_list) { + if (ef->dentry) { + unsigned long ptr = (unsigned long)dentry_list; + + /* Keep the dentry from being freed yet */ + dget(ef->dentry); + + /* + * Paranoid: The dget() above should prevent the dentry + * from being freed and calling eventfs_set_ef_status_free(). + * But just in case, set the link list LSB pointer to 1 + * and have eventfs_set_ef_status_free() check that to + * make sure that if it does happen, it will not think + * the d_fsdata is an event_file. + * + * For this to work, no event_file should be allocated + * on a odd space, as the ef should always be allocated + * to be at least word aligned. Check for that too. + */ + WARN_ON_ONCE(ptr & 1); + + ef->dentry->d_fsdata = (void *)(ptr | 1); + dentry_list = ef->dentry; + ef->dentry = NULL; + } + call_srcu(&eventfs_srcu, &ef->rcu, free_ef); + } + mutex_unlock(&eventfs_mutex); + + while (dentry_list) { + unsigned long ptr; + + dentry = dentry_list; + ptr = (unsigned long)dentry->d_fsdata & ~1UL; + dentry_list = (struct dentry *)ptr; + dentry->d_fsdata = NULL; + d_invalidate(dentry); + mutex_lock(&eventfs_mutex); + /* dentry should now have at least a single reference */ + WARN_ONCE((int)d_count(dentry) < 1, + "dentry %p less than one reference (%d) after invalidate\n", + dentry, d_count(dentry)); + mutex_unlock(&eventfs_mutex); + dput(dentry); + } +} + +/** + * eventfs_remove_events_dir - remove eventfs dir or file from list + * @dentry: events's dentry to be removed. + * + * This function remove events main directory + */ +void eventfs_remove_events_dir(struct dentry *dentry) +{ + struct tracefs_inode *ti; + struct eventfs_inode *ei; + + if (!dentry || !dentry->d_inode) + return; + + ti = get_tracefs(dentry->d_inode); + if (!ti || !(ti->flags & TRACEFS_EVENT_INODE)) + return; + + ei = ti->private; + d_invalidate(dentry); + dput(dentry); + kfree(ei); +} diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h index 54c9cbd0389b..009072792fa3 100644 --- a/include/linux/tracefs.h +++ b/include/linux/tracefs.h @@ -40,6 +40,10 @@ int eventfs_add_events_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops); +void eventfs_remove(struct eventfs_file *ef); + +void eventfs_remove_events_dir(struct dentry *dentry); + struct dentry *tracefs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops); |