Merge tag 'trace-v6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Fix the "bytes" output of the per_cpu stat file

   The tracefs/per_cpu/cpu*/stats "bytes" was giving bogus values as the
   accounting was not accurate. It is suppose to show how many used
   bytes are still in the ring buffer, but even when the ring buffer was
   empty it would still show there were bytes used.

 - Fix a bug in eventfs where reading a dynamic event directory (open)
   and then creating a dynamic event that goes into that diretory screws
   up the accounting.

   On close, the newly created event dentry will get a "dput" without
   ever having a "dget" done for it. The fix is to allocate an array on
   dir open to save what dentries were actually "dget" on, and what ones
   to "dput" on close.

* tag 'trace-v6.6-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  eventfs: Remember what dentries were created on dir open
  ring-buffer: Fix bytes info in per_cpu buffer stats

1 files changed, 70 insertions, 17 deletions

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 9f64e7332796..5f1714089884 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -70,6 +70,7 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
 					  struct dentry *dentry,
 					  unsigned int flags);
 static int dcache_dir_open_wrapper(struct inode *inode, struct file *file);
+static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx);
 static int eventfs_release(struct inode *inode, struct file *file);
 
 static const struct inode_operations eventfs_root_dir_inode_operations = {
@@ -79,7 +80,7 @@ static const struct inode_operations eventfs_root_dir_inode_operations = {
 static const struct file_operations eventfs_file_operations = {
 	.open		= dcache_dir_open_wrapper,
 	.read		= generic_read_dir,
-	.iterate_shared	= dcache_readdir,
+	.iterate_shared	= dcache_readdir_wrapper,
 	.llseek		= generic_file_llseek,
 	.release	= eventfs_release,
 };
@@ -396,6 +397,11 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
 	return ret;
 }
 
+struct dentry_list {
+	void			*cursor;
+	struct dentry		**dentries;
+};
+
 /**
  * eventfs_release - called to release eventfs file/dir
  * @inode: inode to be released
@@ -404,26 +410,25 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
 static int eventfs_release(struct inode *inode, struct file *file)
 {
 	struct tracefs_inode *ti;
-	struct eventfs_inode *ei;
-	struct eventfs_file *ef;
-	struct dentry *dentry;
-	int idx;
+	struct dentry_list *dlist = file->private_data;
+	void *cursor;
+	int i;
 
 	ti = get_tracefs(inode);
 	if (!(ti->flags & TRACEFS_EVENT_INODE))
 		return -EINVAL;
 
-	ei = ti->private;
-	idx = srcu_read_lock(&eventfs_srcu);
-	list_for_each_entry_srcu(ef, &ei->e_top_files, list,
-				 srcu_read_lock_held(&eventfs_srcu)) {
-		mutex_lock(&eventfs_mutex);
-		dentry = ef->dentry;
-		mutex_unlock(&eventfs_mutex);
-		if (dentry)
-			dput(dentry);
+	if (WARN_ON_ONCE(!dlist))
+		return -EINVAL;
+
+	for (i = 0; dlist->dentries[i]; i++) {
+		dput(dlist->dentries[i]);
 	}
-	srcu_read_unlock(&eventfs_srcu, idx);
+
+	cursor = dlist->cursor;
+	kfree(dlist->dentries);
+	kfree(dlist);
+	file->private_data = cursor;
 	return dcache_dir_close(inode, file);
 }
 
@@ -442,22 +447,70 @@ static int dcache_dir_open_wrapper(struct inode *inode, struct file *file)
 	struct tracefs_inode *ti;
 	struct eventfs_inode *ei;
 	struct eventfs_file *ef;
+	struct dentry_list *dlist;
+	struct dentry **dentries = NULL;
 	struct dentry *dentry = file_dentry(file);
+	struct dentry *d;
 	struct inode *f_inode = file_inode(file);
+	int cnt = 0;
 	int idx;
+	int ret;
 
 	ti = get_tracefs(f_inode);
 	if (!(ti->flags & TRACEFS_EVENT_INODE))
 		return -EINVAL;
 
+	if (WARN_ON_ONCE(file->private_data))
+		return -EINVAL;
+
+	dlist = kmalloc(sizeof(*dlist), GFP_KERNEL);
+	if (!dlist)
+		return -ENOMEM;
+
 	ei = ti->private;
 	idx = srcu_read_lock(&eventfs_srcu);
 	list_for_each_entry_srcu(ef, &ei->e_top_files, list,
 				 srcu_read_lock_held(&eventfs_srcu)) {
-		create_dentry(ef, dentry, false);
+		d = create_dentry(ef, dentry, false);
+		if (d) {
+			struct dentry **tmp;
+
+			tmp = krealloc(dentries, sizeof(d) * (cnt + 2), GFP_KERNEL);
+			if (!tmp)
+				break;
+			tmp[cnt] = d;
+			tmp[cnt + 1] = NULL;
+			cnt++;
+			dentries = tmp;
+		}
 	}
 	srcu_read_unlock(&eventfs_srcu, idx);
-	return dcache_dir_open(inode, file);
+	ret = dcache_dir_open(inode, file);
+
+	/*
+	 * dcache_dir_open() sets file->private_data to a dentry cursor.
+	 * Need to save that but also save all the dentries that were
+	 * opened by this function.
+	 */
+	dlist->cursor = file->private_data;
+	dlist->dentries = dentries;
+	file->private_data = dlist;
+	return ret;
+}
+
+/*
+ * This just sets the file->private_data back to the cursor and back.
+ */
+static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx)
+{
+	struct dentry_list *dlist = file->private_data;
+	int ret;
+
+	file->private_data = dlist->cursor;
+	ret = dcache_readdir(file, ctx);
+	dlist->cursor = file->private_data;
+	file->private_data = dlist;
+	return ret;
 }
 
 /**