Re: [RFCv5 3/5] iomap: Add iop's uptodate state handling functions

[Brian Foster <bfoster@redhat.com>]

On Mon, May 08, 2023 at 12:57:58AM +0530, Ritesh Harjani (IBM) wrote:
> Firstly this patch renames iop->uptodate to iop->state bitmap.
> This is because we will add dirty state to iop->state bitmap in later
> patches. So it makes sense to rename the iop->uptodate bitmap to
> iop->state.
> 
> Secondly this patch also adds other helpers for uptodate state bitmap
> handling of iop->state.
> 
> No functionality change in this patch.
> 
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
> ---
>  fs/iomap/buffered-io.c | 78 +++++++++++++++++++++++++++++++-----------
>  1 file changed, 58 insertions(+), 20 deletions(-)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index e732581dc2d4..5103b644e115 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
...
> @@ -43,6 +43,47 @@ static inline struct iomap_page *to_iomap_page(struct folio *folio)
...
> +/*
> + * iop related helpers for checking uptodate/dirty state of per-block
> + * or range of blocks within a folio
> + */
> +static bool iop_test_full_uptodate(struct folio *folio)
> +{
> +	struct iomap_page *iop = to_iomap_page(folio);
> +	struct inode *inode = folio->mapping->host;
> +
> +	WARN_ON(!iop);

It looks like an oops or something is imminent here if iop is NULL. Why
the warn (here and in a couple other places)?

Brian

> +	return iop_bitmap_full(iop, i_blocks_per_folio(inode, folio));
> +}
> +
> +static bool iop_test_block_uptodate(struct folio *folio, unsigned int block)
> +{
> +	struct iomap_page *iop = to_iomap_page(folio);
> +
> +	WARN_ON(!iop);
> +	return iop_test_block(iop, block);
> +}
> +
>  static void iop_set_range_uptodate(struct inode *inode, struct folio *folio,
>  				   size_t off, size_t len)
>  {
> @@ -53,12 +94,11 @@ static void iop_set_range_uptodate(struct inode *inode, struct folio *folio,
>  	unsigned long flags;
>  
>  	if (iop) {
> -		spin_lock_irqsave(&iop->uptodate_lock, flags);
> -		bitmap_set(iop->uptodate, first_blk, nr_blks);
> -		if (bitmap_full(iop->uptodate,
> -				i_blocks_per_folio(inode, folio)))
> +		spin_lock_irqsave(&iop->state_lock, flags);
> +		iop_set_range(iop, first_blk, nr_blks);
> +		if (iop_test_full_uptodate(folio))
>  			folio_mark_uptodate(folio);
> -		spin_unlock_irqrestore(&iop->uptodate_lock, flags);
> +		spin_unlock_irqrestore(&iop->state_lock, flags);
>  	} else {
>  		folio_mark_uptodate(folio);
>  	}
> @@ -79,12 +119,12 @@ static struct iomap_page *iop_alloc(struct inode *inode, struct folio *folio,
>  	else
>  		gfp = GFP_NOFS | __GFP_NOFAIL;
>  
> -	iop = kzalloc(struct_size(iop, uptodate, BITS_TO_LONGS(nr_blocks)),
> +	iop = kzalloc(struct_size(iop, state, BITS_TO_LONGS(nr_blocks)),
>  		      gfp);
>  	if (iop) {
> -		spin_lock_init(&iop->uptodate_lock);
> +		spin_lock_init(&iop->state_lock);
>  		if (folio_test_uptodate(folio))
> -			bitmap_fill(iop->uptodate, nr_blocks);
> +			iop_set_range(iop, 0, nr_blocks);
>  		folio_attach_private(folio, iop);
>  	}
>  	return iop;
> @@ -93,15 +133,13 @@ static struct iomap_page *iop_alloc(struct inode *inode, struct folio *folio,
>  static void iop_free(struct folio *folio)
>  {
>  	struct iomap_page *iop = to_iomap_page(folio);
> -	struct inode *inode = folio->mapping->host;
> -	unsigned int nr_blocks = i_blocks_per_folio(inode, folio);
>  
>  	if (!iop)
>  		return;
>  	WARN_ON_ONCE(atomic_read(&iop->read_bytes_pending));
>  	WARN_ON_ONCE(atomic_read(&iop->write_bytes_pending));
> -	WARN_ON_ONCE(bitmap_full(iop->uptodate, nr_blocks) !=
> -			folio_test_uptodate(folio));
> +	WARN_ON_ONCE(iop_test_full_uptodate(folio) !=
> +		     folio_test_uptodate(folio));
>  	folio_detach_private(folio);
>  	kfree(iop);
>  }
> @@ -132,7 +170,7 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
>  
>  		/* move forward for each leading block marked uptodate */
>  		for (i = first; i <= last; i++) {
> -			if (!test_bit(i, iop->uptodate))
> +			if (!iop_test_block_uptodate(folio, i))
>  				break;
>  			*pos += block_size;
>  			poff += block_size;
> @@ -142,7 +180,7 @@ static void iomap_adjust_read_range(struct inode *inode, struct folio *folio,
>  
>  		/* truncate len if we find any trailing uptodate block(s) */
>  		for ( ; i <= last; i++) {
> -			if (test_bit(i, iop->uptodate)) {
> +			if (iop_test_block_uptodate(folio, i)) {
>  				plen -= (last - i + 1) * block_size;
>  				last = i - 1;
>  				break;
> @@ -450,7 +488,7 @@ bool iomap_is_partially_uptodate(struct folio *folio, size_t from, size_t count)
>  	last = (from + count - 1) >> inode->i_blkbits;
>  
>  	for (i = first; i <= last; i++)
> -		if (!test_bit(i, iop->uptodate))
> +		if (!iop_test_block_uptodate(folio, i))
>  			return false;
>  	return true;
>  }
> @@ -1634,7 +1672,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
>  	 * invalid, grab a new one.
>  	 */
>  	for (i = 0; i < nblocks && pos < end_pos; i++, pos += len) {
> -		if (iop && !test_bit(i, iop->uptodate))
> +		if (iop && !iop_test_block_uptodate(folio, i))
>  			continue;
>  
>  		error = wpc->ops->map_blocks(wpc, inode, pos);
> -- 
> 2.39.2
>