On Thu, Jan 04, 2024 at 09:53:33PM -0800, Christoph Hellwig wrote: > On Sun, Dec 31, 2023 at 12:35:11PM -0800, Darrick J. Wong wrote: > > From: Darrick J. Wong <djwong@xxxxxxxxxx> > > > > Create a simple 'blob array' data structure for storage of arbitrarily > > sized metadata objects that will be used to reconstruct metadata. For > > the intended usage (temporarily storing extended attribute names and > > values) we only have to support storing objects and retrieving them. > > Use the xfile abstraction to store the attribute information in memory > > that can be swapped out. > > Can't this simply be supported by xfiles directly? Just add a > xfile_append that writes at i_size and retuns the offset and we're done? Yeah, xfile could just do an "append and tell me where you wrote it". That said, i_size_read is less direct than reading a u64 out of a struct. Another speedbump with doing that is that eventually xfs_repair ports the xfblob to userspace to support parent pointers. For that, a statx call is much more expensive, so I decided that both implementations should just have their own private u64 write pointer. (Unless you want to sponsor a pwrite variant that actually does "append and tell me where"? ;)) --D
