Re: [RFC PATCH v4 7/8] xfs: reserve blocks for truncating realtime inode

[Darrick J. Wong]

On Fri, May 31, 2024 at 05:42:37AM -0700, Christoph Hellwig wrote:
> > -	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
> > +	resblks = XFS_IS_REALTIME_INODE(ip) ? XFS_DIOSTRAT_SPACE_RES(mp, 0) : 0;
> 
> This probably wants a comment explaining that we need the block
> reservation for bmap btree block allocations / splits that can happen
> because we can split a written extent into one written and one
> unwritten, while for the data fork we'll always just shorten or
> remove extents.

"for the data fork"? <confused>

This always runs on the data fork.  Did you mean "for files with alloc
unit > 1 fsblock"?

> I'd also find this more readable if resblks was initialized to 0,
> and this became a:
> 
> 	if (XFS_IS_REALTIME_INODE(ip))
> 		resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);

Agreed.

--D