Commit 4330397e authored by hujianyang's avatar hujianyang Committed by Miklos Szeredi
Browse files

ovl: discard independent cursor in readdir() 



Since the ovl_dir_cache is stable during a directory reading, the cursor
of struct ovl_dir_file don't need to be an independent entry in the list
of a merged directory.

This patch changes *cursor* to a pointer which points to the entry in the
ovl_dir_cache. After this, we don't need to check *is_cursor* either.

Signed-off-by: default avatarhujianyang <hujianyang@huawei.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
parent 6d900f5a

fs/overlayfs/readdir.c

+14 −24
Original line number Diff line number Diff line
@@ -24,7 +24,6 @@ struct ovl_cache_entry { 
	struct list_head l_node;

	struct rb_node node;

	bool is_whiteout;

	bool is_cursor;

	char name[];

};
@@ -49,7 +48,7 @@ struct ovl_dir_file { 
	bool is_real;

	bool is_upper;

	struct ovl_dir_cache *cache;

	struct ovl_cache_entry cursor;

	struct list_head *cursor;

	struct file *realfile;

	struct file *upperfile;

};
@@ -97,7 +96,6 @@ static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir, 
	p->type = d_type;

	p->ino = ino;

	p->is_whiteout = false;

	p->is_cursor = false;



	if (d_type == DT_CHR) {

		struct dentry *dentry;
@@ -196,7 +194,6 @@ static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry) 
{

	struct ovl_dir_cache *cache = od->cache;



	list_del_init(&od->cursor.l_node);

	WARN_ON(cache->refcount <= 0);

	cache->refcount--;

	if (!cache->refcount) {
@@ -254,6 +251,7 @@ static void ovl_dir_reset(struct file *file) 
	if (cache && ovl_dentry_version_get(dentry) != cache->version) {

		ovl_cache_put(od, dentry);

		od->cache = NULL;

		od->cursor = NULL;

	}

	WARN_ON(!od->is_real && !OVL_TYPE_MERGE(type));

	if (od->is_real && OVL_TYPE_MERGE(type))
@@ -295,17 +293,16 @@ static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list) 


static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)

{

	struct ovl_cache_entry *p;

	struct list_head *p;

	loff_t off = 0;



	list_for_each_entry(p, &od->cache->entries, l_node) {

		if (p->is_cursor)

			continue;

	list_for_each(p, &od->cache->entries) {

		if (off >= pos)

			break;

		off++;

	}

	list_move_tail(&od->cursor.l_node, &p->l_node);

	/* Cursor is safe since the cache is stable */

	od->cursor = p;

}



static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
@@ -344,6 +341,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx) 
{

	struct ovl_dir_file *od = file->private_data;

	struct dentry *dentry = file->f_path.dentry;

	struct ovl_cache_entry *p;



	if (!ctx->pos)

		ovl_dir_reset(file);
@@ -362,20 +360,14 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx) 
		ovl_seek_cursor(od, ctx->pos);

	}



	while (od->cursor.l_node.next != &od->cache->entries) {

		struct ovl_cache_entry *p;



		p = list_entry(od->cursor.l_node.next, struct ovl_cache_entry, l_node);

		/* Skip cursors */

		if (!p->is_cursor) {

			if (!p->is_whiteout) {

	while (od->cursor != &od->cache->entries) {

		p = list_entry(od->cursor, struct ovl_cache_entry, l_node);

		if (!p->is_whiteout)

			if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))

				break;

			}

		od->cursor = p->l_node.next;

		ctx->pos++;

	}

		list_move(&od->cursor.l_node, &p->l_node);

	}

	return 0;

}
@@ -493,11 +485,9 @@ static int ovl_dir_open(struct inode *inode, struct file *file) 
		kfree(od);

		return PTR_ERR(realfile);

	}

	INIT_LIST_HEAD(&od->cursor.l_node);

	od->realfile = realfile;

	od->is_real = !OVL_TYPE_MERGE(type);

	od->is_upper = OVL_TYPE_UPPER(type);

	od->cursor.is_cursor = true;

	file->private_data = od;



	return 0;

CRA Git | Maintained and supported by SUSTech CRA and CCSE