diff --git a/MAINTAINERS b/MAINTAINERS index 509281e9e1695a..012df8ccf34e90 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -22079,6 +22079,7 @@ F: drivers/watchdog/tqmx86_wdt.c TRACING M: Steven Rostedt M: Masami Hiramatsu +R: Mathieu Desnoyers L: linux-kernel@vger.kernel.org L: linux-trace-kernel@vger.kernel.org S: Maintained diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index f8a594a50ae628..0b90869fd805cd 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -27,16 +27,16 @@ /* * eventfs_mutex protects the eventfs_inode (ei) dentry. Any access * to the ei->dentry must be done under this mutex and after checking - * if ei->is_freed is not set. The ei->dentry is released under the - * mutex at the same time ei->is_freed is set. If ei->is_freed is set - * then the ei->dentry is invalid. + * if ei->is_freed is not set. When ei->is_freed is set, the dentry + * is on its way to being freed after the last dput() is made on it. */ static DEFINE_MUTEX(eventfs_mutex); /* * The eventfs_inode (ei) itself is protected by SRCU. It is released from * its parent's list and will have is_freed set (under eventfs_mutex). - * After the SRCU grace period is over, the ei may be freed. + * After the SRCU grace period is over and the last dput() is called + * the ei is freed. */ DEFINE_STATIC_SRCU(eventfs_srcu); @@ -95,7 +95,7 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry, if (!(dentry->d_inode->i_mode & S_IFDIR)) { if (!ei->entry_attrs) { ei->entry_attrs = kzalloc(sizeof(*ei->entry_attrs) * ei->nr_entries, - GFP_KERNEL); + GFP_NOFS); if (!ei->entry_attrs) { ret = -ENOMEM; goto out; @@ -326,7 +326,8 @@ create_file_dentry(struct eventfs_inode *ei, int idx, struct eventfs_attr *attr = NULL; struct dentry **e_dentry = &ei->d_children[idx]; struct dentry *dentry; - bool invalidate = false; + + WARN_ON_ONCE(!inode_is_locked(parent->d_inode)); mutex_lock(&eventfs_mutex); if (ei->is_freed) { @@ -348,15 +349,8 @@ create_file_dentry(struct eventfs_inode *ei, int idx, mutex_unlock(&eventfs_mutex); - /* The lookup already has the parent->d_inode locked */ - if (!lookup) - inode_lock(parent->d_inode); - dentry = create_file(name, mode, attr, parent, data, fops); - if (!lookup) - inode_unlock(parent->d_inode); - mutex_lock(&eventfs_mutex); if (IS_ERR_OR_NULL(dentry)) { @@ -365,12 +359,14 @@ create_file_dentry(struct eventfs_inode *ei, int idx, * created the dentry for this e_dentry. In which case * use that one. * - * Note, with the mutex held, the e_dentry cannot have content - * and the ei->is_freed be true at the same time. + * If ei->is_freed is set, the e_dentry is currently on its + * way to being freed, don't return it. If e_dentry is NULL + * it means it was already freed. */ - dentry = *e_dentry; - if (WARN_ON_ONCE(dentry && ei->is_freed)) + if (ei->is_freed) dentry = NULL; + else + dentry = *e_dentry; /* The lookup does not need to up the dentry refcount */ if (dentry && !lookup) dget(dentry); @@ -387,17 +383,14 @@ create_file_dentry(struct eventfs_inode *ei, int idx, * Otherwise it means two dentries exist with the same name. */ WARN_ON_ONCE(!ei->is_freed); - invalidate = true; + dentry = NULL; } mutex_unlock(&eventfs_mutex); - if (invalidate) - d_invalidate(dentry); - - if (lookup || invalidate) + if (lookup) dput(dentry); - return invalidate ? NULL : dentry; + return dentry; } /** @@ -437,9 +430,10 @@ static struct dentry * create_dir_dentry(struct eventfs_inode *pei, struct eventfs_inode *ei, struct dentry *parent, bool lookup) { - bool invalidate = false; struct dentry *dentry = NULL; + WARN_ON_ONCE(!inode_is_locked(parent->d_inode)); + mutex_lock(&eventfs_mutex); if (pei->is_freed || ei->is_freed) { mutex_unlock(&eventfs_mutex); @@ -456,15 +450,8 @@ create_dir_dentry(struct eventfs_inode *pei, struct eventfs_inode *ei, } mutex_unlock(&eventfs_mutex); - /* The lookup already has the parent->d_inode locked */ - if (!lookup) - inode_lock(parent->d_inode); - dentry = create_dir(ei, parent); - if (!lookup) - inode_unlock(parent->d_inode); - mutex_lock(&eventfs_mutex); if (IS_ERR_OR_NULL(dentry) && !ei->is_freed) { @@ -473,8 +460,8 @@ create_dir_dentry(struct eventfs_inode *pei, struct eventfs_inode *ei, * created the dentry for this e_dentry. In which case * use that one. * - * Note, with the mutex held, the e_dentry cannot have content - * and the ei->is_freed be true at the same time. + * If ei->is_freed is set, the e_dentry is currently on its + * way to being freed. */ dentry = ei->dentry; if (dentry && !lookup) @@ -493,16 +480,14 @@ create_dir_dentry(struct eventfs_inode *pei, struct eventfs_inode *ei, * Otherwise it means two dentries exist with the same name. */ WARN_ON_ONCE(!ei->is_freed); - invalidate = true; + dentry = NULL; } mutex_unlock(&eventfs_mutex); - if (invalidate) - d_invalidate(dentry); - if (lookup || invalidate) + if (lookup) dput(dentry); - return invalidate ? NULL : dentry; + return dentry; } /** @@ -632,7 +617,7 @@ static int add_dentries(struct dentry ***dentries, struct dentry *d, int cnt) { struct dentry **tmp; - tmp = krealloc(*dentries, sizeof(d) * (cnt + 2), GFP_KERNEL); + tmp = krealloc(*dentries, sizeof(d) * (cnt + 2), GFP_NOFS); if (!tmp) return -1; tmp[cnt] = d; @@ -698,6 +683,7 @@ static int dcache_dir_open_wrapper(struct inode *inode, struct file *file) return -ENOMEM; } + inode_lock(parent->d_inode); list_for_each_entry_srcu(ei_child, &ei->children, list, srcu_read_lock_held(&eventfs_srcu)) { d = create_dir_dentry(ei, ei_child, parent, false); @@ -730,6 +716,7 @@ static int dcache_dir_open_wrapper(struct inode *inode, struct file *file) cnt++; } } + inode_unlock(parent->d_inode); srcu_read_unlock(&eventfs_srcu, idx); ret = dcache_dir_open(inode, file); diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 5b54948514fe21..ae648deed019cc 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -509,20 +509,15 @@ struct dentry *eventfs_start_creating(const char *name, struct dentry *parent) struct dentry *dentry; int error; + /* Must always have a parent. */ + if (WARN_ON_ONCE(!parent)) + return ERR_PTR(-EINVAL); + 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