diff --git a/MAINTAINERS b/MAINTAINERS
index 509281e9e1695a5a7b7d81e091f7835d1514cc59..012df8ccf34e9003586528f1424ab73ca60234ba 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22079,6 +22079,7 @@ F: drivers/watchdog/tqmx86_wdt.c
TRACING
M: Steven Rostedt <rostedt@goodmis.org>
M: Masami Hiramatsu <mhiramat@kernel.org>
+R: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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 f8a594a50ae628b3116f9918adafd7e7630b0f89..0b90869fd805cd62ab6db7cf924ee0cad8c86eaf 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 5b54948514fe21de97b1fe0c35b3fa2a1d91de46..ae648deed019cc72e12bcbb3ca788eee78008d7b 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