On Fri, Feb 19, 2021 at 12:34:03PM +0000, Matthew Wilcox wrote:
> > IORING_OP_GETDENTS may or may not update the specified directory's
> > file offset, and the file offset should not be relied upon having
> > any particular value during or after an IORING_OP_GETDENTS call.
>
> This doesn't give me the warm fuzzies. What I might suggest
> is either passing a parameter to iterate_dir() or breaking out an
> iterate_dir_nofpos() to make IORING_OP_GETDENTS more of a READV operation.
> ie the equivalent of this:
>
> @@ -37,7 +37,7 @@
> } while (0)
>
>
> -int iterate_dir(struct file *file, struct dir_context *ctx)
> +int iterate_dir(struct file *file, struct dir_context *ctx, bool use_fpos)
> {
> struct inode *inode = file_inode(file);
> bool shared = false;
> @@ -60,12 +60,14 @@ int iterate_dir(struct file *file, struct dir_context *ctx)
>
> res = -ENOENT;
> if (!IS_DEADDIR(inode)) {
> - ctx->pos = file->f_pos;
> + if (use_fpos)
> + ctx->pos = file->f_pos;
> if (shared)
> res = file->f_op->iterate_shared(file, ctx);
> else
> res = file->f_op->iterate(file, ctx);
> - file->f_pos = ctx->pos;
> + if (use_fpos)
> + file->f_pos = ctx->pos;
> fsnotify_access(file);
> file_accessed(file);
> }
>
> That way there's no need to play with llseek or take a mutex on the
> f_pos of the directory.
I'll try this!
