Re: [PATCH 6/6] hfsplus: switch address_space_operations on iomap-based support

[Christoph Hellwig <hch@lst.de>]

> @@ -605,20 +606,32 @@ void hfsplus_file_truncate(struct inode *inode)
>  		inode->i_ino, (long long)hip->phys_size, inode->i_size);
>  
>  	if (inode->i_size > hip->phys_size) {
> +		if (S_ISREG(inode->i_mode)) {
> +			res = hfsplus_iomap_cont_expand(inode, inode->i_size);
> +			if (res)
> +				return;
> +
> +			mark_inode_dirty(inode);
> +		} else {
> +			struct address_space *mapping = inode->i_mapping;
> +			struct folio *folio;
> +			void *fsdata = NULL;
> +
> +			res = hfsplus_write_begin(NULL, mapping,
> +						  inode->i_size, 0,
> +						  &folio, &fsdata);
> +			if (res)
> +				return;
> +
> +			res = generic_write_end(NULL, mapping,
> +						inode->i_size, 0, 0,
> +						folio, fsdata);
> +			if (res < 0)
> +				return;
> +
> +			mark_inode_dirty(inode);

Can't this use the iomap zeroing helpers?

> -static int hfsplus_writepages(struct address_space *mapping,
> +static int hfsplus_legacy_writepages(struct address_space *mapping,
>  			      struct writeback_control *wbc)
>  {
>  	return mpage_writepages(mapping, wbc, hfsplus_get_block);
> @@ -196,8 +139,8 @@ static int hfsplus_writepages(struct address_space *mapping,
>  const struct address_space_operations hfsplus_btree_aops = {
>  	.dirty_folio	= block_dirty_folio,
>  	.invalidate_folio = block_invalidate_folio,
> -	.read_folio	= hfsplus_read_folio,
> -	.writepages	= hfsplus_writepages,
> +	.read_folio	= hfsplus_legacy_read_folio,
> +	.writepages	= hfsplus_legacy_writepages,

Would btree be a better name then legacy?  So the story here is
there is a btree inode, and you want to keep the buffer_head based
path for this, at least for now?

> @@ -290,10 +274,22 @@ static int hfsplus_setattr(struct mnt_idmap *idmap,
>  	    attr->ia_size != i_size_read(inode)) {
>  		inode_dio_wait(inode);
>  		if (attr->ia_size > inode->i_size) {
> -			error = generic_cont_expand_simple(inode,
> -							   attr->ia_size);
> -			if (error)
> -				return error;
> +			if (S_ISREG(inode->i_mode)) {
> +				loff_t old_size = inode->i_size;
> +
> +				i_size_write(inode, attr->ia_size);
> +				error = hfsplus_iomap_cont_expand(inode,
> +								  attr->ia_size);
> +				if (error) {
> +					i_size_write(inode, old_size);
> +					return error;
> +				}
> +			} else {
> +				error = generic_cont_expand_simple(inode,
> +								   attr->ia_size);
> +				if (error)
> +					return error;
> +			}

You're not suppoed to see ->setattr for ATTR_SIZE for anything but
regular files from the VFS.  I don't think there's any hfsplus specific
path that could cause this either, could it?