Re: [PATCH v17 04/10] fs/ntfs3: Add file operations and implementation

[Matthew Wilcox <willy@infradead.org>]

On Thu, Dec 31, 2020 at 06:23:55PM +0300, Konstantin Komarov wrote:
> +/*
> + * file_operations::iterate_shared
> + *
> + * Use non sorted enumeration.
> + * We have an example of broken volume where sorted enumeration
> + * counts each name twice
> + */
> +static int ntfs_readdir(struct file *file, struct dir_context *ctx)
> +{
> +	const struct INDEX_ROOT *root;
> +	u64 vbo;
> +	size_t bit;
> +	loff_t eod;
> +	int err = 0;
> +	struct inode *dir = file_inode(file);
> +	struct ntfs_inode *ni = ntfs_i(dir);
> +	struct super_block *sb = dir->i_sb;
> +	struct ntfs_sb_info *sbi = sb->s_fs_info;
> +	loff_t i_size = i_size_read(dir);
> +	u32 pos = ctx->pos;
> +	u8 *name = NULL;
> +	struct indx_node *node = NULL;
> +	u8 index_bits = ni->dir.index_bits;
> +
> +	/* name is a buffer of PATH_MAX length */
> +	static_assert(NTFS_NAME_LEN * 4 < PATH_MAX);
> +
> +	eod = i_size + sbi->record_size;
> +
> +	if (pos >= eod)
> +		return 0;
> +
> +	if (!dir_emit_dots(file, ctx))
> +		return 0;
> +
> +	/* allocate PATH_MAX bytes */
> +	name = __getname();
> +	if (!name)
> +		return -ENOMEM;
> +
> +	ni_lock(ni);

What is this lock protecting?